G2Cdb::Gene report

Gene id
Gene symbol
Jup (MGI)
Mus musculus
junction plakoglobin
G00001843 (Homo sapiens)

Databases (8)

Curated Gene
OTTMUSG00000006276 (Vega mouse gene)
ENSMUSG00000001552 (Ensembl mouse gene)
16480 (Entrez Gene)
1018 (G2Cdb plasticity & disease)
Gene Expression
NM_010593 (Allen Brain Atlas)
173325 (OMIM)
Marker Symbol
MGI:96650 (MGI)
Protein Sequence
Q02257 (UniProt)

Synonyms (3)

  • PG
  • gamma-catenin
  • plakoglobin

Literature (77)

Pubmed - other

  • Sex differences in expression and subcellular localization of heart rhythm determinant proteins.

    Thomas NM, Jasmin JF, Lisanti MP and Iacobas DA

    Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1300 Morris Park Ave., Kennedy Center, New York, NY 10461, USA. neil.thomas@einstein.yu.edu

    To evaluate sex differences in protein expression in the heart, we performed Western blot studies on a subset of Heart Rhythm Determinant (HRD) proteins. We examined key components of a variety of types of mechanical and electrical junctions including, connexin43, plakophilin-2, N-cadherin and plakoglobin, ankyrin-2 and actin. We describe novel findings in sex differences in cardiac protein expression and membrane localization. For most proteins examined, sex differences were significantly more pronounced in the membrane compartment than in overall expression. These studies extend our previous findings in microarray studies to demonstrate that sex differences in gene expression are likely to confer distinct functional properties on male and female myocardium.

    Funded by: NHLBI NIH HHS: R01 HL092001, R01HL092001

    Biochemical and biophysical research communications 2011;406;1;117-22

  • Cardiac tissue-restricted deletion of plakoglobin results in progressive cardiomyopathy and activation of {beta}-catenin signaling.

    Li J, Swope D, Raess N, Cheng L, Muller EJ and Radice GL

    Center for Translational Medicine, Department of Medicine, Rm. 309, College Bldg., 1025 Walnut St., Philadelphia, PA 19107, USA.

    Mutations in the plakoglobin (JUP) gene have been identified in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients. However, the mechanisms underlying plakoglobin dysfunction involved in the pathogenesis of ARVC remain poorly understood. Plakoglobin is a component of both desmosomes and adherens junctions located at the intercalated disc (ICD) of cardiomyocytes, where it functions to link cadherins to the cytoskeleton. In addition, plakoglobin functions as a signaling protein via its ability to modulate the Wnt/β-catenin signaling pathway. To investigate the role of plakoglobin in ARVC, we generated an inducible cardiorestricted knockout (CKO) of the plakoglobin gene in mice. Plakoglobin CKO mice exhibited progressive loss of cardiac myocytes, extensive inflammatory infiltration, fibrous tissue replacement, and cardiac dysfunction similar to those of ARVC patients. Desmosomal proteins from the ICD were decreased, consistent with altered desmosome ultrastructure in plakoglobin CKO hearts. Despite gap junction remodeling, plakoglobin CKO hearts were refractory to induced arrhythmias. Ablation of plakoglobin caused increase β-catenin stabilization associated with activated AKT and inhibition of glycogen synthase kinase 3β. Finally, β-catenin/TCF transcriptional activity may contribute to the cardiac hypertrophy response in plakoglobin CKO mice. This novel model of ARVC demonstrates for the first time how plakoglobin affects β-catenin activity in the heart and its implications for disease pathogenesis.

    Funded by: NHLBI NIH HHS: HL081569, R01 HL081569, R01 HL081569-05

    Molecular and cellular biology 2011;31;6;1134-44

  • A high-resolution anatomical atlas of the transcriptome in the mouse embryo.

    Diez-Roux G, Banfi S, Sultan M, Geffers L, Anand S, Rozado D, Magen A, Canidio E, Pagani M, Peluso I, Lin-Marq N, Koch M, Bilio M, Cantiello I, Verde R, De Masi C, Bianchi SA, Cicchini J, Perroud E, Mehmeti S, Dagand E, Schrinner S, Nürnberger A, Schmidt K, Metz K, Zwingmann C, Brieske N, Springer C, Hernandez AM, Herzog S, Grabbe F, Sieverding C, Fischer B, Schrader K, Brockmeyer M, Dettmer S, Helbig C, Alunni V, Battaini MA, Mura C, Henrichsen CN, Garcia-Lopez R, Echevarria D, Puelles E, Garcia-Calero E, Kruse S, Uhr M, Kauck C, Feng G, Milyaev N, Ong CK, Kumar L, Lam M, Semple CA, Gyenesei A, Mundlos S, Radelof U, Lehrach H, Sarmientos P, Reymond A, Davidson DR, Dollé P, Antonarakis SE, Yaspo ML, Martinez S, Baldock RA, Eichele G and Ballabio A

    Telethon Institute of Genetics and Medicine, Naples, Italy.

    Ascertaining when and where genes are expressed is of crucial importance to understanding or predicting the physiological role of genes and proteins and how they interact to form the complex networks that underlie organ development and function. It is, therefore, crucial to determine on a genome-wide level, the spatio-temporal gene expression profiles at cellular resolution. This information is provided by colorimetric RNA in situ hybridization that can elucidate expression of genes in their native context and does so at cellular resolution. We generated what is to our knowledge the first genome-wide transcriptome atlas by RNA in situ hybridization of an entire mammalian organism, the developing mouse at embryonic day 14.5. This digital transcriptome atlas, the Eurexpress atlas (http://www.eurexpress.org), consists of a searchable database of annotated images that can be interactively viewed. We generated anatomy-based expression profiles for over 18,000 coding genes and over 400 microRNAs. We identified 1,002 tissue-specific genes that are a source of novel tissue-specific markers for 37 different anatomical structures. The quality and the resolution of the data revealed novel molecular domains for several developing structures, such as the telencephalon, a novel organization for the hypothalamus, and insight on the Wnt network involved in renal epithelial differentiation during kidney development. The digital transcriptome atlas is a powerful resource to determine co-expression of genes, to identify cell populations and lineages, and to identify functional associations between genes relevant to development and disease.

    Funded by: Medical Research Council: MC_U127527203; Telethon: TGM11S03

    PLoS biology 2011;9;1;e1000582

  • Homologs of genes expressed in Caenorhabditis elegans GABAergic neurons are also found in the developing mouse forebrain.

    Hammock EA, Eagleson KL, Barlow S, Earls LR, Miller DM and Levitt P

    Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA. liz.hammock@vanderbilt.edu

    Background: In an effort to identify genes that specify the mammalian forebrain, we used a comparative approach to identify mouse homologs of transcription factors expressed in developing Caenorhabditis elegans GABAergic neurons. A cell-specific microarray profiling study revealed a set of transcription factors that are highly expressed in embryonic C. elegans GABAergic neurons.

    Results: Bioinformatic analyses identified mouse protein homologs of these selected transcripts and their expression pattern was mapped in the mouse embryonic forebrain by in situ hybridization. A review of human homologs indicates several of these genes are potential candidates in neurodevelopmental disorders.

    Conclusions: Our comparative approach has revealed several novel candidates that may serve as future targets for studies of mammalian forebrain development.

    Funded by: NICHD NIH HHS: HD015052; NIMH NIH HHS: R21MH077302, T32 MH065215

    Neural development 2010;5;32

  • Plakoglobin regulates cell motility through Rho- and fibronectin-dependent Src signaling.

    Todorović V, Desai BV, Patterson MJ, Amargo EV, Dubash AD, Yin T, Jones JC and Green KJ

    Department of Pathology, 303 E. Chicago Avenue, Northwestern University, Chicago, IL 60611, USA.

    We previously showed that the cell-cell junction protein plakoglobin (PG) not only suppresses motility of keratinocytes in contact with each other, but also, unexpectedly, of single cells. Here we show that PG deficiency results in extracellular matrix (ECM)-dependent disruption of mature focal adhesions and cortical actin organization. Plating PG⁻/⁻ cells onto ECM deposited by PG+/⁻ cells partially restored normal cell morphology and inhibited PG⁻/⁻ cell motility. In over 70 adhesion molecules whose expression we previously showed to be altered in PG⁻/⁻ cells, a substantial decrease in fibronectin (FN) in PG⁻/⁻ cells stood out. Re-introduction of PG into PG⁻/⁻ cells restored FN expression, and keratinocyte motility was reversed by plating PG⁻/⁻ cells onto FN. Somewhat surprisingly, based on previously reported roles for PG in regulating gene transcription, PG-null cells exhibited an increase, not a decrease, in FN promoter activity. Instead, PG was required for maintenance of FN mRNA stability. PG⁻/⁻ cells exhibited an increase in activated Src, one of the kinases controlled by FN, a phenotype reversed by plating PG⁻/⁻ cells on ECM deposited by PG+/⁻ keratinocytes. PG⁻/⁻ cells also exhibited Src-independent activation of the small GTPases Rac1 and RhoA. Both Src and RhoA inhibition attenuated PG⁻/⁻ keratinocyte motility. We propose a novel role for PG in regulating cell motility through distinct ECM-Src and RhoGTPase-dependent pathways, influenced in part by PG-dependent regulation of FN mRNA stability.

    Funded by: NCI NIH HHS: R01 CA122151, R01CA122151, T32 CA070085; NIAMS NIH HHS: F32 AR055444, R01 AR041836, R01 AR043380, R01 AR054184, R01 AR054184-18, R01 AR054184-20, R01AR041836-17S1, R01AR43380

    Journal of cell science 2010;123;Pt 20;3576-86

  • Myozap, a novel intercalated disc protein, activates serum response factor-dependent signaling and is required to maintain cardiac function in vivo.

    Seeger TS, Frank D, Rohr C, Will R, Just S, Grund C, Lyon R, Luedde M, Koegl M, Sheikh F, Rottbauer W, Franke WW, Katus HA, Olson EN and Frey N

    Professor of Internal Medicine and Cardiology, Department of Cardiology and Angiology, University Hospital Schleswig-Holstein, Campus Kiel, Schittenhelmstr. 12, 24105 Kiel, Germany.

    Rationale: The intercalated disc (ID) is a highly specialized cell-cell contact structure that ensures mechanical and electric coupling of contracting cardiomyocytes. Recently, the ID has been recognized to be a hot spot of cardiac disease, in particular inherited cardiomyopathy.

    Objective: Given its complex structure and function we hypothesized that important molecular constituents of the ID still remain unknown.

    Using a bioinformatics screen, we discovered and cloned a previously uncharacterized 54 kDa cardiac protein which we termed Myozap (Myocardium-enriched zonula occludens-1-associated protein). Myozap is strongly expressed in the heart and lung. In cardiac tissue it localized to the ID and directly binds to desmoplakin and zonula occludens-1. In a yeast 2-hybrid screen for additional binding partners of Myozap we identified myosin phosphatase-RhoA interacting protein (MRIP), a negative regulator of Rho activity. Myozap, in turn, strongly activates SRF-dependent transcription through its ERM (Ezrin/radixin/moesin)-like domain in a Rho-dependent fashion. Finally, in vivo knockdown of the Myozap ortholog in zebrafish led to severe contractile dysfunction and cardiomyopathy.

    Conclusions: Taken together, these findings reveal Myozap as a previously unrecognized component of a Rho-dependent signaling pathway that links the intercalated disc to cardiac gene regulation. Moreover, its subcellular localization and the observation of a severe cardiac phenotype in zebrafish, implicate Myozap in the pathogenesis of cardiomyopathy.

    Funded by: NHLBI NIH HHS: R01 HL083371, R01 HL083371-05, R01 HL095780

    Circulation research 2010;106;5;880-90

  • VE-PTP maintains the endothelial barrier via plakoglobin and becomes dissociated from VE-cadherin by leukocytes and by VEGF.

    Nottebaum AF, Cagna G, Winderlich M, Gamp AC, Linnepe R, Polaschegg C, Filippova K, Lyck R, Engelhardt B, Kamenyeva O, Bixel MG, Butz S and Vestweber D

    Max-Planck-Institute of Molecular Biomedicine, Münster, Germany.

    We have shown recently that vascular endothelial protein tyrosine phosphatase (VE-PTP), an endothelial-specific membrane protein, associates with vascular endothelial (VE)-cadherin and enhances VE-cadherin function in transfected cells (Nawroth, R., G. Poell, A. Ranft, U. Samulowitz, G. Fachinger, M. Golding, D.T. Shima, U. Deutsch, and D. Vestweber. 2002. EMBO J. 21:4885-4895). We show that VE-PTP is indeed required for endothelial cell contact integrity, because down-regulation of its expression enhanced endothelial cell permeability, augmented leukocyte transmigration, and inhibited VE-cadherin-mediated adhesion. Binding of neutrophils as well as lymphocytes to endothelial cells triggered rapid (5 min) dissociation of VE-PTP from VE-cadherin. This dissociation was only seen with tumor necrosis factor alpha-activated, but not resting, endothelial cells. Besides leukocytes, vascular endothelial growth factor also rapidly dissociated VE-PTP from VE-cadherin, indicative of a more general role of VE-PTP in the regulation of endothelial cell contacts. Dissociation of VE-PTP and VE-cadherin in endothelial cells was accompanied by tyrosine phoshorylation of VE-cadherin, beta-catenin, and plakoglobin. Surprisingly, only plakoglobin but not beta-catenin was necessary for VE-PTP to support VE-cadherin adhesion in endothelial cells. In addition, inhibiting the expression of VE-PTP preferentially increased tyrosine phosphorylation of plakoglobin but not beta-catenin. In conclusion, leukocytes interacting with endothelial cells rapidly dissociate VE-PTP from VE-cadherin, weakening endothelial cell contacts via a mechanism that requires plakoglobin but not beta-catenin.

    The Journal of experimental medicine 2008;205;12;2929-45

  • Canonical Wnt signaling regulates organ-specific assembly and differentiation of CNS vasculature.

    Stenman JM, Rajagopal J, Carroll TJ, Ishibashi M, McMahon J and McMahon AP

    Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.

    Every organ depends on blood vessels for oxygen and nutrients, but the vasculature associated with individual organs can be structurally and molecularly diverse. The central nervous system (CNS) vasculature consists of a tightly sealed endothelium that forms the blood-brain barrier, whereas blood vessels of other organs are more porous. Wnt7a and Wnt7b encode two Wnt ligands produced by the neuroepithelium of the developing CNS coincident with vascular invasion. Using genetic mouse models, we found that these ligands directly target the vascular endothelium and that the CNS uses the canonical Wnt signaling pathway to promote formation and CNS-specific differentiation of the organ's vasculature.

    Funded by: NHLBI NIH HHS: HL076393; NIDDK NIH HHS: DK054364, R37 DK054364

    Science (New York, N.Y.) 2008;322;5905;1247-50

  • Diverse roles of E-cadherin in the morphogenesis of the submandibular gland: insights into the formation of acinar and ductal structures.

    Walker JL, Menko AS, Khalil S, Rebustini I, Hoffman MP, Kreidberg JA and Kukuruzinska MA

    Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.

    The formation of acinar and ductal structures during epithelial tissue branching morphogenesis is not well understood. We report that in the mouse submandibular gland (SMG), acinar and ductal cell fates are determined early in embryonic morphogenesis with E-cadherin playing pivotal roles in development. We identified two morphologically distinct cell populations at the single bud stage, destined for different functions. The outer layer of columnar cells with organized E-cadherin junctions expressed the neonatal acinar marker B1 by E13.5, demonstrating their acinar fate. The interior cells initially lacked distinct E-cadherin junctions, but with morphogenesis formed cytokeratin 7 (K7) -positive ductal structures with organized E-cadherin junctions and F-actin filaments. Inhibition of E-cadherin function with either siRNA or function blocking antibody caused extensive apoptosis of ductal cells and aberrantly dilated lumens, providing the first evidence that E-cadherin regulates ductal lumen formation during branching morphogenesis of the salivary gland.

    Funded by: NEI NIH HHS: EY014798, R24 EY014798, R24 EY014798-05; NIDCR NIH HHS: DE010183, DE014437, R01 DE010183, R01 DE010183-11, R01 DE010183-13, R01 DE014437, R01 DE014437-03, R01 DE014437-04A2, R01 DE014437-05

    Developmental dynamics : an official publication of the American Association of Anatomists 2008;237;11;3128-41

  • Plakoglobin is required for effective intermediate filament anchorage to desmosomes.

    Acehan D, Petzold C, Gumper I, Sabatini DD, Müller EJ, Cowin P and Stokes DL

    Skirball Institute for Biomolecular Medicine, New York University School of Medicine, New York, New York 10012, USA.

    Desmosomes are adhesive junctions that provide mechanical coupling between cells. Plakoglobin (PG) is a major component of the intracellular plaque that serves to connect transmembrane elements to the cytoskeleton. We have used electron tomography and immunolabeling to investigate the consequences of PG knockout on the molecular architecture of the intracellular plaque in cultured keratinocytes. Although knockout keratinocytes form substantial numbers of desmosome-like junctions and have a relatively normal intercellular distribution of desmosomal cadherins, their cytoplasmic plaques are sparse and anchoring of intermediate filaments is defective. In the knockout, beta-catenin appears to substitute for PG in the clustering of cadherins, but is unable to recruit normal levels of plakophilin-1 and desmoplakin to the plaque. By comparing tomograms of wild type and knockout desmosomes, we have assigned particular densities to desmoplakin and described their interaction with intermediate filaments. Desmoplakin molecules are more extended in wild type than knockout desmosomes, as if intermediate filament connections produced tension within the plaque. On the basis of our observations, we propose a particular assembly sequence, beginning with cadherin clustering within the plasma membrane, followed by recruitment of plakophilin and desmoplakin to the plaque, and ending with anchoring of intermediate filaments, which represents the key to adhesive strength.

    Funded by: NIGMS NIH HHS: R01 GM071044

    The Journal of investigative dermatology 2008;128;11;2665-75

  • New insights into cadherin function in epidermal sheet formation and maintenance of tissue integrity.

    Tinkle CL, Pasolli HA, Stokes N and Fuchs E

    Laboratory of Mammalian Cell Biology and Development, Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10065, USA.

    Co-expression and gene linkage have hampered elucidating the physiological relevance of cadherins in mammalian tissues. Here, we combine conditional gene ablation and transgenic RNA interference to uncover new roles for E- and P-cadherins in epidermal sheet formation in vitro and maintenance of epidermal integrity in vivo. By devising skin-specific RNAi technology, we demonstrate that cadherin inhibition in vivo impairs junction formation and intercellular adhesion and increases apoptosis. These defects compromise epidermal barrier function and tissue integrity. In vitro, with only E-cadherin missing, epidermal sheet formation is delayed, but when both cadherins are suppressed, defects extend to adherens junctions, desmosomes, tight junctions and cortical actin dynamics. Using different rescue strategies, we show that cadherin level rather than subtype is critical. Finally, by comparing conditional loss-of-function studies of epidermal catenins and cadherins, we dissect cadherin-dependent and independent roles of adherens junction components in tissue physiology.

    Funded by: Howard Hughes Medical Institute; NCI NIH HHS: CA09673, T32 CA009673; NIAMS NIH HHS: R01 AR027883, R01-AR27883; NIGMS NIH HHS: GM07739, T32 GM007739

    Proceedings of the National Academy of Sciences of the United States of America 2008;105;40;15405-10

  • Glucocorticoid receptor is required for skin barrier competence.

    Bayo P, Sanchis A, Bravo A, Cascallana JL, Buder K, Tuckermann J, Schütz G and Pérez P

    Centro de Investigación Príncipe Felipe, Valencia, Avenida Autopista del Saler 16, Camino de las Moreras, E-46013 Valencia, Spain.

    To investigate the contribution of the glucocorticoid receptor (GR) in skin development and the mechanisms underlying this function, we have analyzed two mouse models in which GR has been functionally inactivated: the knockout GR(-/-) mice and the dimerization mutant GR(dim/dim) that mediates defective DNA binding-dependent transcription. Because GR null mice die perinatally, we evaluated skin architecture of late embryos by histological, immunohistochemical, and electron microscopy studies. Loss of function of GR resulted in incomplete epidermal stratification with dramatically abnormal differentiation of GR(-/-), but not GR(+/-) embryos, as demonstrated by the lack of loricrin, filaggrin, and involucrin markers. Skin sections of GR(-/-) embryos revealed edematous basal and lower spinous cells, and electron micrographs showed increased intercellular spaces between keratinocytes and reduced number of desmosomes. The absent terminal differentiation in GR(-/-) embryos correlated with an impaired activation of caspase-14, which is required for the processing of profilaggrin into filaggrin at late embryo stages. Accordingly, the skin barrier competence was severely compromised in GR(-/-) embryos. Cultured mouse primary keratinocytes from GR(-/-) mice formed colonies with cells of heterogeneous size and morphology that showed increased growth and apoptosis, indicating that GR regulates these processes in a cell-autonomous manner. The activity of ERK1/2 was constitutively augmented in GR(-/-) skin and mouse primary keratinocytes relative to wild type, which suggests that GR modulates skin homeostasis, at least partially, by antagonizing ERK function. Moreover, the epidermis of GR(+/dim) and GR(dim/dim) embryos appeared normal, thus suggesting that DNA-binding-independent actions of GR are sufficient to mediate epidermal and hair follicle development during embryogenesis.

    Endocrinology 2008;149;3;1377-88

  • Long-term, multilineage hematopoiesis occurs in the combined absence of beta-catenin and gamma-catenin.

    Jeannet G, Scheller M, Scarpellino L, Duboux S, Gardiol N, Back J, Kuttler F, Malanchi I, Birchmeier W, Leutz A, Huelsken J and Held W

    Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, Lausanne, Switzerland.

    The canonical Wnt signaling pathway plays key roles in stem-cell maintenance, progenitor cell expansion, and lineage decisions. Transcriptional responses induced by Wnt depend on the association of either beta-catenin or gamma-catenin with lymphoid enhancer factor/T cell factor transcription factors. Here we show that hematopoiesis, including thymopoiesis, is normal in the combined absence of beta- and gamma-catenin. Double-deficient hematopoietic stem cells maintain long-term repopulation capacity and multilineage differentiation potential. Unexpectedly, 2 independent ex vivo reporter gene assays show that Wnt signal transmission is maintained in double-deficient hematopoietic stem cells, thymocytes, or peripheral T cells. In contrast, Wnt signaling is strongly reduced in thymocytes lacking TCF-1 or in nonhematopoietic cells devoid of beta-catenin. These data provide the first evidence that hematopoietic cells can transduce canonical Wnt signals in the combined absence of beta- and gamma-catenin.

    Blood 2008;111;1;142-9

  • Simultaneous loss of beta- and gamma-catenin does not perturb hematopoiesis or lymphopoiesis.

    Koch U, Wilson A, Cobas M, Kemler R, Macdonald HR and Radtke F

    Swiss Institute for Experimental Cancer Research (ISREC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Epalinges, Switzerland.

    Hematopietic stem cells (HSCs) maintain life-long hematopoiesis in the bone marrow via their ability to self-renew and to differentiate into all blood lineages. Although a central role for the canonical wnt signaling pathway has been suggested in HSC self-renewal as well as in the development of B and T cells, conditional deletion of beta-catenin (which is considered to be essential for Wnt signaling) has no effect on hematopoiesis or lymphopoiesis. Here, we address whether this discrepancy can be explained by a redundant and compensatory function of gamma-catenin, a close homolog of beta-catenin. Unexpectedly, we find that combined deficiency of beta- and gamma-catenin in hematopoietic progenitors does not impair their ability to self-renew and to reconstitute all myeloid, erythroid, and lymphoid lineages, even in competitive mixed chimeras and serial transplantations. These results exclude an essential role for canonical Wnt signaling (as mediated by beta- and/or gamma-catenin) during hematopoiesis and lymphopoiesis.

    Blood 2008;111;1;160-4

  • Defining the roles of beta-catenin and plakoglobin in LEF/T-cell factor-dependent transcription using beta-catenin/plakoglobin-null F9 cells.

    Shimizu M, Fukunaga Y, Ikenouchi J and Nagafuchi A

    Division of Cellular Interactions, Institute of Molecular Embryology and Genetics, Kumamoto University, Honjo 2-2-1, Kumamoto 860-0811, Japan.

    beta-Catenin functions as a transcriptional regulator in Wnt signaling. Its function is regulated by a specific destruction system. Plakoglobin is a close homologue of beta-catenin in mammalian cells and is regulated in a similar fashion. When beta-catenin or plakoglobin is exogenously expressed in cells, endogenous beta-catenin is stabilized, which complicates estimation of the transcriptional activities of exogenously expressed proteins. To facilitate the design of experiments aimed at investigating the transcriptional activities of beta-catenin and plakoglobin, we utilized F9 cells in which we knocked out endogenous beta-catenin and/or plakoglobin by gene deletion and exogenously expressed wild-type and mutant beta-catenin and/or plakoglobin. We show that C-terminally deleted beta-catenin, but not plakoglobin, has a strong dominant-negative effect on transcription without altering the nuclear accumulation of beta-catenin. Moreover, we show that Wnt-3a activation of LEF/T-cell factor (TCF)-dependent transcription depends on beta-catenin but not on plakoglobin. Using chimeras of beta-catenin and plakoglobin, we demonstrate that plakoglobin has the potential to function in transcriptional regulation but is not responsible for Wnt-3a signaling in F9 cells. Our data show that preferential nuclear accumulation of beta-catenin is not necessarily linked to its transcriptional activity. We also clearly demonstrate that plakoglobin is insufficient for LEF/TCF-dependent transcriptional activation by Wnt-3a in F9 cells.

    Molecular and cellular biology 2008;28;2;825-35

  • Loss of mXinalpha, an intercalated disk protein, results in cardiac hypertrophy and cardiomyopathy with conduction defects.

    Gustafson-Wagner EA, Sinn HW, Chen YL, Wang DZ, Reiter RS, Lin JL, Yang B, Williamson RA, Chen J, Lin CI and Lin JJ

    Department of Biological Sciences, University of Iowa, Iowa City, IA 52242, USA.

    The intercalated disk protein Xin was originally discovered in chicken striated muscle and implicated in cardiac morphogenesis. In the mouse, there are two homologous genes, mXinalpha and mXinbeta. The human homolog of mXinalpha, Cmya1, maps to chromosomal region 3p21.2-21.3, near a dilated cardiomyopathy with conduction defect-2 locus. Here we report that mXinalpha-null mouse hearts are hypertrophied and exhibit fibrosis, indicative of cardiomyopathy. A significant upregulation of mXinbeta likely provides partial compensation and accounts for the viability of the mXinalpha-null mice. Ultrastructural studies of mXinalpha-null mouse hearts reveal intercalated disk disruption and myofilament disarray. In mXinalpha-null mice, there is a significant decrease in the expression level of p120-catenin, beta-catenin, N-cadherin, and desmoplakin, which could compromise the integrity of the intercalated disks and functionally weaken adhesion, leading to cardiac defects. Additionally, altered localization and decreased expression of connexin 43 are observed in the mXinalpha-null mouse heart, which, together with previously observed abnormal electrophysiological properties of mXinalpha-deficient mouse ventricular myocytes, could potentially lead to conduction defects. Indeed, ECG recordings on isolated, perfused hearts (Langendorff preparations) show a significantly prolonged QT interval in mXinalpha-deficient hearts. Thus mXinalpha functions in regulating the hypertrophic response and maintaining the structural integrity of the intercalated disk in normal mice, likely through its association with adherens junctional components and actin cytoskeleton. The mXinalpha-knockout mouse line provides a novel model of cardiac hypertrophy and cardiomyopathy with conduction defects.

    Funded by: NHLBI NIH HHS: HL-075015, R01 HL066100, R01 HL075015, R01 HL075015-04

    American journal of physiology. Heart and circulatory physiology 2007;293;5;H2680-92

  • EUCOMM--the European conditional mouse mutagenesis program.

    Friedel RH, Seisenberger C, Kaloff C and Wurst W

    GSF-National Research Center for Environment and Health, Institute of Developmental Genetics, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany.

    Functional analysis of the mammalian genome is an enormous challenge for biomedical scientists. To facilitate this endeavour, the European Conditional Mouse Mutagenesis Program (EUCOMM) aims at generating up to 12 000 mutations by gene trapping and up to 8000 mutations by gene targeting in mouse embryonic stem (ES) cells. These mutations can be rendered into conditional alleles, allowing Cre recombinase-mediated disruption of gene function in a time- and tissue-specific manner. Furthermore, the EUCOMM program will generate up to 320 mouse lines from the EUCOMM resource and up to 20 new Cre driver mouse lines. The EUCOMM resource of vectors, mutant ES cell lines and mutant mice will be openly available to the scientific community. EUCOMM will be one of the cornerstones of an international effort to create a global mouse mutant resource.

    Briefings in functional genomics & proteomics 2007;6;3;180-5

  • Plakoglobin-dependent disruption of the desmosomal plaque in pemphigus vulgaris.

    de Bruin A, Caldelari R, Williamson L, Suter MM, Hunziker T, Wyder M and Müller EJ

    Institute of Animal Pathology and DermFocus Vetsuisse Faculty, Berne, Switzerland.

    We recently reported that the pathogenesis of pemphigus vulgaris (PV), an autoimmune blistering skin disorder, is driven by the accumulation of c-Myc secondary to abrogation of plakoglobin (PG)-mediated transcriptional c-Myc suppression. PG knock-out mouse keratinocytes express high levels of c-Myc and resemble PVIgG-treated wild-type keratinocytes in most respects. However, they fail to accumulate nuclear c-Myc and loose intercellular adhesion in response to PVIgG-treatment like wild-type keratinocytes. This suggested that PG is also required for propagation of the PVIgG-induced events between augmented c-Myc expression and acantholysis. Here, we addressed this possibility by comparing PVIgG-induced changes in the desmosomal organization between wild-type and PG knock-out keratinocytes. We found that either bivalent PVIgG or monovalent PV-Fab (known to trigger blister formation in vivo) disrupt the linear organization of all major desmosomal components along cell borders in wild-type keratinocytes, simultaneously with a reduction in intercellular adhesive strength. In contrast, PV-Fab failed to affect PG knock-out keratinocytes while PVIgG cross-linked their desmosomal cadherins without significantly affecting desmoplakin. These results identify PG as a principle effector of the PVIgG-induced signals downstream of c-Myc that disrupt the desmosomal plaque at the plasma membrane.

    Experimental dermatology 2007;16;6;468-75

  • Plakoglobin deficiency protects keratinocytes from apoptosis.

    Dusek RL, Godsel LM, Chen F, Strohecker AM, Getsios S, Harmon R, Müller EJ, Caldelari R, Cryns VL and Green KJ

    Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.

    The armadillo family protein plakoglobin (Pg) is a well-characterized component of anchoring junctions, where it functions to mediate cell-cell adhesion and maintain epithelial tissue integrity. Although its closest homolog beta-catenin acts in the Wnt signaling pathway to dictate cell fate and promote proliferation and survival, the role of Pg in these processes is not well understood. Here, we investigate how Pg affects the survival of mouse keratinocytes by challenging both Pg-null cells and their heterozygote counterparts with apoptotic stimuli. Our results indicate that Pg deletion protects keratinocytes from apoptosis, with null cells exhibiting delayed mitochondrial cytochrome c release and activation of caspase-3. Pg-null keratinocytes also exhibit increased messenger RNA and protein levels of the anti-apoptotic molecule Bcl-X(L) compared to heterozygote controls. Importantly, reintroduction of Pg into the null cells shifts their phenotype towards that of the Pg+/- keratinocytes, providing further evidence that Pg plays a direct role in regulating cell survival. Taken together, our results suggest that in addition to its adhesive role in epithelia, Pg may also function in contrast to the pro-survival tendencies of beta-catenin, to potentiate death in cells damaged by apoptotic stimuli, perhaps limiting the potential for the propagation of mutations and cellular transformation.

    Funded by: NCI NIH HHS: R01CA122151, T32 CA09560; NIAMS NIH HHS: R01AR41836

    The Journal of investigative dermatology 2007;127;4;792-801

  • Upregulation of gamma-catenin compensates for the loss of beta-catenin in adult cardiomyocytes.

    Zhou J, Qu J, Yi XP, Graber K, Huber L, Wang X, Gerdes AM and Li F

    Cardiovascular Research Institute, South Dakota Health Research Foundation, 1100 East 21st St., Suite 700, Sioux Falls, SD 57105, USA.

    Recent progresses in signal transduction have revealed that beta-catenin signaling controls embryonic development, tumorigenesis, cell shape, and polarity. The role of this pathway in myocyte shape regulation during cardiac hypertrophy and failure is, however, not clearly defined. Since homozygous knockout of beta-catenin is embryonically lethal, we have deleted beta-catenin genes specifically in the heart of adult mice by crossing loxP-flanked beta-catenin mice with transgenic mice expressing tamoxifen-activated MerCreMer protein (MCM) driven by the alpha-myosin heavy chain promoter. Administration of tamoxifen to homozygous loxP-flanked beta-catenin mice positive for MCM induces the deletion of beta-catenin only in cardiomyocytes. Immunolabeling with beta-catenin antibody demonstrates that 90% of cardiomyocytes completely lose their beta-catenin expression but maintain normal rod-shaped morphology. The intercalated disk of cardiomyocytes lacking beta-catenin is morphologically unremarkable with normal distribution of vinculin, N-cadherin, desmoplakin, ZO-1, connexin43, and alpha-, gamma-, and p120 catenins. The expression level of these proteins, except that of gamma-catenin, is also similar in tamoxifen-treated and control mice with both homozygous loxP-flanked beta-catenin genes and the MCM transgene. Western blot analyses reveal that gamma-catenin increases in the heart of beta-catenin knockout mice compared with controls. Confocal microscopy also demonstrates that gamma-catenin has significantly increased in the intercalated disk of cardiomyocytes lacking beta-catenin. Echocardiographic data indicate that the knockout mice maintain normal ventricular geometry and cardiac function. The results suggest that upregulation of gamma-catenin can compensate for the loss of beta-catenin in cardiomyocytes to maintain normal cardiac structure and function.

    Funded by: NCRR NIH HHS: P20 RR017662; NHLBI NIH HHS: HL-62459, HL-72166

    American journal of physiology. Heart and circulatory physiology 2007;292;1;H270-6

  • Irf6 is a key determinant of the keratinocyte proliferation-differentiation switch.

    Richardson RJ, Dixon J, Malhotra S, Hardman MJ, Knowles L, Boot-Handford RP, Shore P, Whitmarsh A and Dixon MJ

    Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK.

    The epidermis is a highly organized structure, the integrity of which is central to the protection of an organism. Development and subsequent maintenance of this tissue depends critically on the intricate balance between proliferation and differentiation of a resident stem cell population; however, the signals controlling the proliferation-differentiation switch in vivo remain elusive. Here, we show that mice carrying a homozygous missense mutation in interferon regulatory factor 6 (Irf6), the homolog of the gene mutated in the human congenital disorders Van der Woude syndrome and popliteal pterygium syndrome, have a hyperproliferative epidermis that fails to undergo terminal differentiation, resulting in soft tissue fusions. We further demonstrate that mice that are compound heterozygotes for mutations in Irf6 and the gene encoding the cell cycle regulator protein stratifin (Sfn; also known as 14-3-3sigma) show similar defects of keratinizing epithelia. Our results indicate that Irf6 is a key determinant of the keratinocyte proliferation-differentiation switch and that Irf6 and Sfn interact genetically in this process.

    Funded by: Medical Research Council: G0400264; NIDCR NIH HHS: P50-DE016215; Wellcome Trust: 064732, 066173

    Nature genetics 2006;38;11;1329-34

  • Age- and training-dependent development of arrhythmogenic right ventricular cardiomyopathy in heterozygous plakoglobin-deficient mice.

    Kirchhof P, Fabritz L, Zwiener M, Witt H, Schäfers M, Zellerhoff S, Paul M, Athai T, Hiller KH, Baba HA, Breithardt G, Ruiz P, Wichter T and Levkau B

    Department of Cardiology and Angiology, Hospital of the University of Muenster, Germany. kirchhp@uni-muenster.de

    Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disorder that causes sudden death and right ventricular heart failure in the young. Clinical data suggest that competitive sports may provoke ARVC in susceptible persons. Genetically, loss-of-function mutations in desmosomal proteins (plakophilin, desmoplakin, or plakoglobin) have been associated with ARVC. To test the hypothesis that reduced desmosomal protein expression causes ARVC, we studied the cardiac effects of heterozygous plakoglobin deficiency in mice.

    Ten-month-old heterozygous plakoglobin-deficient mice (plakoglobin+/-) had increased right ventricular volume, reduced right ventricular function, and spontaneous ventricular ectopy (all P<0.05). Left ventricular size and function were not altered. Isolated, perfused plakoglobin+/- hearts had spontaneous ventricular tachycardia of right ventricular origin and prolonged right ventricular conduction times compared with wild-type hearts. Endurance training accelerated the development of right ventricular dysfunction and arrhythmias in plakoglobin+/- mice. Histology and electron microscopy did not identify right ventricular abnormalities in affected animals.

    Conclusions: Heterozygous plakoglobin deficiency provokes ARVC. Manifestation of the phenotype is accelerated by endurance training. This suggests a functional role for plakoglobin and training in the development of ARVC.

    Circulation 2006;114;17;1799-806

  • Intracellular substrates of brain-enriched receptor protein tyrosine phosphatase rho (RPTPrho/PTPRT).

    Besco JA, Hooft van Huijsduijnen R, Frostholm A and Rotter A

    Department of Pharmacology, The Ohio State University, 333 W 10th Ave., Columbus, OH 43210, USA. besco.1@osu.edu

    Receptor protein tyrosine phosphatase rho (RPTPrho/PTPRT) is a transmembrane protein that is highly expressed in the developing and adult central nervous system. It is a member of the RPTP R2B subfamily, which includes PTPkappa, PTPmu and PCP-2. Glutathione-S-transferase (GST) pulldown assays were used to show that RPTPrho interacts with several adherens junctional proteins in brain, including E-cadherin, N-cadherin, VE-cadherin (cadherin-5), desmoglein, alpha, beta and gamma catenin, p120(ctn) and alpha-actinin. With the exception of E-cadherin and alpha-actinin, binding was considerably reduced at high sodium concentrations. Furthermore, immunoprecipitation phosphatase assays indicated that E-cadherin, and to a far lesser extent p120(ctn), were tyrosine dephosphorylated by a recombinant RPTPrho intracellular fragment, and thus, were likely to be primary substrates for RPTPrho. The interaction of RPTPrho with adherens junctional components suggests that this phosphatase may transduce extracellular signals to the actin cytoskeleton and thereby play a role in regulating cadherin-mediated cell adhesion in the central nervous system.

    Funded by: NIMH NIH HHS: MH 57415

    Brain research 2006;1116;1;50-7

  • Pemphigus vulgaris identifies plakoglobin as key suppressor of c-Myc in the skin.

    Williamson L, Raess NA, Caldelari R, Zakher A, de Bruin A, Posthaus H, Bolli R, Hunziker T, Suter MM and Müller EJ

    Molecular Dermatology, Institute Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.

    The autoimmune disease pemphigus vulgaris (PV) manifests as loss of keratinocyte cohesion triggered by autoantibody binding to desmoglein (Dsg)3, an intercellular adhesion molecule of mucous membranes, epidermis, and epidermal stem cells. Here we describe a so far unknown signaling cascade activated by PV antibodies. It extends from a transient enhanced turn over of cell surface-exposed, nonkeratin-anchored Dsg3 and associated plakoglobin (PG), through to depletion of nuclear PG, and as one of the consequences, abrogation of PG-mediated c-Myc suppression. In PV patients (6/6), this results in pathogenic c-Myc overexpression in all targeted tissues, including the stem cell compartments. In summary, these results show that PV antibodies act via PG to abolish the c-Myc suppression required for both maintenance of epidermal stem cells in their niche and controlled differentiation along the epidermal lineage. Besides a completely novel insight into PV pathogenesis, these data identify PG as a potent modulator of epithelial homeostasis via its role as a key suppressor of c-Myc.

    The EMBO journal 2006;25;14;3298-309

  • Suppression of canonical Wnt/beta-catenin signaling by nuclear plakoglobin recapitulates phenotype of arrhythmogenic right ventricular cardiomyopathy.

    Garcia-Gras E, Lombardi R, Giocondo MJ, Willerson JT, Schneider MD, Khoury DS and Marian AJ

    Section of Cardiology and Center for Cardiac Development, Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA.

    Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVC) is a genetic disease caused by mutations in desmosomal proteins. The phenotypic hallmark of ARVC is fibroadipocytic replacement of cardiac myocytes, which is a unique phenotype with a yet-to-be-defined molecular mechanism. We established atrial myocyte cell lines expressing siRNA against desmoplakin (DP), responsible for human ARVC. We show suppression of DP expression leads to nuclear localization of the desmosomal protein plakoglobin and a 2-fold reduction in canonical Wnt/beta-catenin signaling through Tcf/Lef1 transcription factors. The ensuing phenotype is increased expression of adipogenic and fibrogenic genes and accumulation of fat droplets. We further show that cardiac-restricted deletion of Dsp, encoding DP, impairs cardiac morphogenesis and leads to high embryonic lethality in the homozygous state. Heterozygous DP-deficient mice exhibited excess adipocytes and fibrosis in the myocardium, increased myocyte apoptosis, cardiac dysfunction, and ventricular arrhythmias, thus recapitulating the phenotype of human ARVC. We believe our results provide for a novel molecular mechanism for the pathogenesis of ARVC and establish cardiac-restricted DP-deficient mice as a model for human ARVC. These findings could provide for the opportunity to identify new diagnostic markers and therapeutic targets in patients with ARVC.

    Funded by: NHLBI NIH HHS: P50-HL42267, R01 HL068884, R01 HL088498, R01 HL088498-01A1, R01 HL088498-02, R01-HL68884

    The Journal of clinical investigation 2006;116;7;2012-21

  • Stabilization of plakoglobin and enhanced keratinocyte cell-cell adhesion by intracellular O-glycosylation.

    Hu P, Berkowitz P, Madden VJ and Rubenstein DS

    Department of Dermatology, University of North Carolina, Chapel Hill, North Carolina 27599-7287, USA.

    O-Glycosylation modifies and regulates a variety of intracellular proteins. Plakoglobin, which functions in both cell-cell adhesion and signal transduction, is modified by O-glycosylation; however, the significance is unknown. To investigate the functional consequence of plakoglobin O-glycosylation, we cloned and overexpressed in keratinocytes murine O-GlcNAc transferase (mOGT). Over expression of mOGT in murine keratinocytes resulted in (i) glycosylation of plakoglobin and (ii) increased levels of plakoglobin due to post-translational stabilization of plakoglobin. Additionally, overexpression of mOGT in keratinocytes correlated with increased staining for cell-cell adhesion proteins and greater cell-cell adhesion. These observations suggest that O-glycosylation functions to regulate the post-translational stability of plakoglobin and keratinocyte cell-cell adhesion.

    Funded by: NIAID NIH HHS: R01 AI49427

    The Journal of biological chemistry 2006;281;18;12786-91

  • Cdc42 controls progenitor cell differentiation and beta-catenin turnover in skin.

    Wu X, Quondamatteo F, Lefever T, Czuchra A, Meyer H, Chrostek A, Paus R, Langbein L and Brakebusch C

    Max Planck Institute of Biochemistry, Heisenberg Group Regulation of Cytoskeletal Organization, Department of Molecular Medicine, 82152 Martinsried, Germany.

    Differentiation of skin stem cells into hair follicles (HFs) requires the inhibition of beta-catenin degradation, which is controlled by a complex containing axin and the protein kinase GSK3beta. Using conditional gene targeting in mice, we show now that the small GTPase Cdc42 is crucial for differentiation of skin progenitor cells into HF lineage and that it regulates the turnover of beta-catenin. In the absence of Cdc42, degradation of beta-catenin was increased corresponding to a decreased phosphorylation of GSK3beta at Ser 9 and an increased phosphorylation of axin, which is known to be required for binding of beta-catenin to the degradation machinery. Cdc42-mediated regulation of beta-catenin turnover was completely dependent on PKCzeta, which associated with Cdc42, Par6, and Par3. These data suggest that Cdc42 regulation of beta-catenin turnover is important for terminal differentiation of HF progenitor cells in vivo.

    Genes & development 2006;20;5;571-85

  • Desmocollin 3 is required for pre-implantation development of the mouse embryo.

    Den Z, Cheng X, Merched-Sauvage M and Koch PJ

    Department of Dermatology, Baylor College of Medicine, Houston, TX 77030, USA.

    Desmocollin 3 (Dsc3) is a transmembrane glycoprotein that belongs to the cadherin family of cell adhesion receptors. Together with desmoglein(s), it forms the transmembrane core of desmosomes, a multiprotein complex involved in cell adhesion, organization of the cytoskeleton, cell sorting and cell signaling. Previous reports have suggested that Dsc3 synthesis is largely restricted to stratified epithelia, and that it plays a role in the proper differentiation of these tissues during mammalian embryonic development. To test these hypotheses, we generated Dsc3-null mice. Unexpectedly, homozygous mutants show a pre-implantation lethal phenotype. In fact, most mutants die even before mature desmosomes are formed in the embryo, suggesting a new and unexpected role of Dsc3 during early development.

    Funded by: NIAMS NIH HHS: AR50439

    Journal of cell science 2006;119;Pt 3;482-9

  • A role for chromosomal protein HMGN1 in corneal maturation.

    Birger Y, Davis J, Furusawa T, Rand E, Piatigorsky J and Bustin M

    National Cancer Institute, Bethesda, MD 20892, USA.

    Corneal differentiation and maturation are associated with major changes in the expression levels of numerous genes, including those coding for the chromatin-binding high-mobility group (HMG) proteins. Here we report that HMGN1, a nucleosome-binding protein that alters the structure and activity of chromatin, affects the development of the corneal epithelium in mice. The corneal epithelium of Hmgn1(-/-) mice is thin, has a reduced number of cells, is poorly stratified, is depleted of suprabasal wing cells, and its most superficial cell layer blisters. In mature Hmgn1(-/-)mice, the basal cells retain the ovoid shape of immature cells, and rest directly on the basal membrane which is disorganized. Gene expression was modified in Hmgn1(-/-) corneas: glutathione-S-transferase (GST)alpha 4 and GST omega 1, epithelial layer-specific markers, were selectively reduced while E-cadherin and alpha-, beta-, and gamma-catenin, components of adherens junctions, were increased. Immunofluorescence analysis reveals a complete co-localization of HMGN1 and p 63 in small clusters of basal corneal epithelial cells of wild-type mice, and an absence of p 63 expressing cells in the central region of the Hmgn1(-/-) cornea. We suggest that interaction of HMGN1 with chromatin modulates the fidelity of gene expression and affects corneal development and maturation.

    Funded by: Intramural NIH HHS: Z01 BC004496-30

    Differentiation; research in biological diversity 2006;74;1;19-29

  • Mechanisms of plakoglobin-dependent adhesion: desmosome-specific functions in assembly and regulation by epidermal growth factor receptor.

    Yin T, Getsios S, Caldelari R, Godsel LM, Kowalczyk AP, Müller EJ and Green KJ

    Department of Pathology and Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.

    Plakoglobin (PG) is a member of the Armadillo family of adhesion/signaling proteins that can be incorporated into both adherens junctions and desmosomes. Loss of PG results in defects in the mechanical integrity of heart and skin and decreased adhesive strength in keratinocyte cultures established from the skin of PG knock-out (PG-/-) mice, the latter of which cannot be compensated for by overexpressing the closely related beta-catenin. In this study, we examined the mechanisms of PG-regulated adhesion in murine keratinocytes. Biochemical and morphological analyses indicated that junctional incorporation of desmosomal, but not adherens junction, components was impaired in PG-/- cells compared with PG+/- controls. Re-expression of PG, but not beta-catenin, in PG-/- cells largely reversed these effects, indicating a key role for PG in desmosome assembly. Epidermal growth factor (EGF) receptor activation resulted in Tyr phosphorylation of PG, which was accompanied by a loss of desmoplakin from desmosomes and decreased adhesive strength following 18-h EGF treatment. Importantly, introduction of a phosphorylation-deficient PG mutant into PG null cells prevented the EGF receptor-dependent loss of desmoplakin from junctions, attenuating the effects of long term EGF treatment on cell adhesion. Therefore, PG is essential for maintaining and regulating adhesive strength in keratinocytes largely through its contributions to desmosome assembly and structure. As a target for modulation by EGF, regulation of PG-dependent adhesion may play an important role during wound healing and tumor metastasis.

    Funded by: NIAMS NIH HHS: R01AR048266, R01AR41836, R01AR43380; NIDCR NIH HHS: P01 DE12328

    The Journal of biological chemistry 2005;280;48;40355-63

  • Beta-catenin is essential for pancreatic acinar but not islet development.

    Murtaugh LC, Law AC, Dor Y and Melton DA

    Department of Molecular and Cellular Biology and Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA.

    Despite our increasingly sophisticated understanding of transcriptional regulation in pancreas development, we know relatively little about the extrinsic signaling pathways involved in this process. We show here that the early pancreatic epithelium exhibits a specific enrichment in unphosphorylated beta-catenin protein, a hallmark of activation of the canonical Wnt signaling pathway. To determine if this pathway is functionally required for normal pancreas development, we have specifically deleted the beta-catenin gene in these cells. Pancreata developing without beta-catenin are hypoplastic, although their early progenitors appear normal and exhibit no premature differentiation or death. Surprisingly, and in marked contrast to its role in the intestine, loss of beta-catenin does not significantly perturb islet endocrine cell mass or function. The major defect of the beta-catenin-deficient pancreas is an almost complete lack of acinar cells, which normally comprise the majority of the organ. beta-Catenin appears to be cell-autonomously required for the specification of acinar cells, rather than for their survival or maintenance, as deletion of beta-catenin specifically in differentiated acinar cells has no effect. Thus, our data are consistent with a crucial role for canonical Wnt signals in acinar lineage specification and differentiation.

    Development (Cambridge, England) 2005;132;21;4663-74

  • Identification of the regions of PECAM-1 involved in beta- and gamma-catenin associations.

    Biswas P, Zhang J, Schoenfeld JD, Schoenfeld D, Gratzinger D, Canosa S and Madri JA

    Department of Pathology, Yale University School of Medicine, New Haven, CT, USA. Purba_Biswas@brown.edu

    Platelet endothelial cell adhesion molecule-1 (PECAM-1) binds tyrosine-phosphorylated beta-catenin and modulates beta-catenin localization and sequestration. The biological significance of this interaction, while still unclear, it has been postulated to be involved in modulating adherens junction dynamics in response to perturbants [J. Clin. Invest. 109 (2002) 383]. Here we demonstrate that tyrosine-phosphorylated beta-catenin, and to a lesser extent unphosphorylated beta-catenin, interact with a portion of the cytoplasmic domain of PECAM-1 encoded by exon 15. Using RT-PCR, we obtained products representing alternatively spliced PECAM-1 isoforms from mouse kidney total mRNA and generated PECAM-1-GST constructs expressing full length and naturally occurring alternatively spliced PECAM-1 variants. Co-precipitation assays revealed that the protein sequence encoded by exon 15 is necessary for beta-catenin binding. Transfections using deletion mutants confirmed the importance of the exon 15 sequence in this interaction. In contrast, gamma-catenin-PECAM-1 interactions are thought to be modulated by an as yet undefined PECAM-1 serine phosphorylation and appear to mediate dynamic PECAM-1 intermediate filament cytoskeletal interactions [J. Biol. Chem. 275 (2000) 21435]. Here we demonstrate that the PECAM-1-gamma-catenin interaction occurs via an exon 13-mediated process. GST-pull-down assays illustrated the importance of the exon 13 sequence in this interaction. Further, using site-directed mutagenesis of S(673) to C and D and S(669 and 670) to C, we confirmed the importance of S(673) and its phosphorylation state as a mediator of gamma-catenin-PECAM-1 binding. Our studies define the exons of the PECAM-1 cytoplasmic domain that is involved in mediating these PECAM-1-catenin family member interactions and will allow investigators to better define the biological functions resulting from these interactions.

    Funded by: NHLBI NIH HHS: R37-HL28373; NIDDK NIH HHS: P01-DK38979

    Biochemical and biophysical research communications 2005;329;4;1225-33

  • Plakoglobin suppresses keratinocyte motility through both cell-cell adhesion-dependent and -independent mechanisms.

    Yin T, Getsios S, Caldelari R, Kowalczyk AP, Müller EJ, Jones JC and Green KJ

    Departments of Pathology and Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA.

    Plakoglobin (PG) is a member of the Armadillo family of adhesion/signaling proteins and has been shown to play a critical role in the organization of desmosomes and tissue integrity. Because dissolution of intercellular junctions is frequently an initial step in the onset of epithelial cell migration, we examined whether loss of PG promotes cell motility by compromising adhesive strength. Keratinocyte cultures established from PG-/-mice exhibited weakened adhesion and increased motility in transwell migration assays; both were restored by reintroducing PG through adenoviral infection. Interestingly, single PG-/- cells also exhibited increased motility, which was suppressed by reintroducing PG, but not the closely related beta-catenin. Whereas both N- and C-terminally truncated PG deletion mutants restored adhesion, only N-terminally deleted PG, but not C-terminally deleted PG, suppressed single-cell migration. Furthermore, both the chemical inhibitor PP2 and dominant-negative Src tyrosine kinase inhibited single-cell motility in PG-/- cells, whereas constitutively active Src overcame the inhibitory effect of PG. These data demonstrate that PG strengthens adhesion and suppresses motility in mouse keratinocytes, through both intercellular adhesion-dependent and -independent mechanisms, the latter of which may involve suppression of Src signaling through a mechanism requiring the PG C terminus.

    Funded by: NIAMS NIH HHS: R01 AR 048266, R01 AR 41836, R01 AR 43380, R01 AR041836, R01 AR043380, R01 AR048266; NIDCR NIH HHS: P01 DE 12328, P01 DE012328

    Proceedings of the National Academy of Sciences of the United States of America 2005;102;15;5420-5

  • E-cadherin is essential for in vivo epidermal barrier function by regulating tight junctions.

    Tunggal JA, Helfrich I, Schmitz A, Schwarz H, Günzel D, Fromm M, Kemler R, Krieg T and Niessen CM

    Center for Molecular Medicine, University of Cologne (CMMC), Cologne, Germany.

    Cadherin adhesion molecules are key determinants of morphogenesis and tissue architecture. Nevertheless, the molecular mechanisms responsible for the morphogenetic contributions of cadherins remain poorly understood in vivo. Besides supporting cell-cell adhesion, cadherins can affect a wide range of cellular functions that include activation of cell signalling pathways, regulation of the cytoskeleton and control of cell polarity. To determine the role of E-cadherin in stratified epithelium of the epidermis, we have conditionally inactivated its gene in mice. Here we show that loss of E-cadherin in the epidermis in vivo results in perinatal death of mice due to the inability to retain a functional epidermal water barrier. Absence of E-cadherin leads to improper localization of key tight junctional proteins, resulting in permeable tight junctions and thus altered epidermal resistance. In addition, both Rac and activated atypical PKC, crucial for tight junction formation, are mislocalized. Surprisingly, our results indicate that E-cadherin is specifically required for tight junction, but not desmosome, formation and this appears to involve signalling rather than cell contact formation.

    The EMBO journal 2005;24;6;1146-56

  • Defining the roles of beta-catenin and plakoglobin in cell-cell adhesion: isolation of beta-catenin/plakoglobin-deficient F9 cells.

    Fukunaga Y, Liu H, Shimizu M, Komiya S, Kawasuji M and Nagafuchi A

    Division of Cellular Interactions, Institute of Molecular Embryology and Genetics, Kumamoto University, Honjo 2-2-1, Kumamoto 860-0811, Japan.

    F9 teratocarcinoma cells in which beta-catenin and/or plakoglobin genes are knocked-out were generated and investigated in an effort to define the role of beta-catenin and plakoglobin in cell adhesion. Loss of beta-catenin expression only did not affect cadherin-mediated cell adhesion activity. Loss of both beta-catenin and plakoglobin expression, however, severely affected the strong cell adhesion activity of cadherin. In beta-catenin-deficient cells, the amount of plakoglobin associated with E-cadherin dramatically increased. In beta-catenin/plakoglobin-deficient cells, the level of E-cadherin and alpha-catenin markedly decreased. In these cells, E-cadherin formed large aggregates in cytoplasm and membrane localization of alpha-catenin was barely detected. These data confirmed that beta-catenin or plakoglobin is required for alpha-catenin to form complex with E-cadherin. It was also demonstrated that plakoglobin can compensate for the absence of beta-catenin. Moreover it was suggested that beta-catenin or plakoglobin is required not only for the cell adhesion activity but also for the stable expression and cell surface localization of E-cadherin.

    Cell structure and function 2005;30;2;25-34

  • Requirement of plakophilin 2 for heart morphogenesis and cardiac junction formation.

    Grossmann KS, Grund C, Huelsken J, Behrend M, Erdmann B, Franke WW and Birchmeier W

    Max Delbrueck Center for Molecular Medicine (MDC), D-13092 Berlin, Germany.

    Plakophilins are proteins of the armadillo family that function in embryonic development and in the adult, and when mutated can cause disease. We have ablated the plakophilin 2 gene in mice. The resulting mutant mice exhibit lethal alterations in heart morphogenesis and stability at mid-gestation (E10.5-E11), characterized by reduced trabeculation, disarrayed cytoskeleton, ruptures of cardiac walls, and blood leakage into the pericardiac cavity. In the absence of plakophilin 2, the cytoskeletal linker protein desmoplakin dissociates from the plaques of the adhering junctions that connect the cardiomyocytes and forms granular aggregates in the cytoplasm. By contrast, embryonic epithelia show normal junctions. Thus, we conclude that plakophilin 2 is important for the assembly of junctional proteins and represents an essential morphogenic factor and architectural component of the heart.

    The Journal of cell biology 2004;167;1;149-60

  • The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

    Gerhard DS, Wagner L, Feingold EA, Shenmen CM, Grouse LH, Schuler G, Klein SL, Old S, Rasooly R, Good P, Guyer M, Peck AM, Derge JG, Lipman D, Collins FS, Jang W, Sherry S, Feolo M, Misquitta L, Lee E, Rotmistrovsky K, Greenhut SF, Schaefer CF, Buetow K, Bonner TI, Haussler D, Kent J, Kiekhaus M, Furey T, Brent M, Prange C, Schreiber K, Shapiro N, Bhat NK, Hopkins RF, Hsie F, Driscoll T, Soares MB, Casavant TL, Scheetz TE, Brown-stein MJ, Usdin TB, Toshiyuki S, Carninci P, Piao Y, Dudekula DB, Ko MS, Kawakami K, Suzuki Y, Sugano S, Gruber CE, Smith MR, Simmons B, Moore T, Waterman R, Johnson SL, Ruan Y, Wei CL, Mathavan S, Gunaratne PH, Wu J, Garcia AM, Hulyk SW, Fuh E, Yuan Y, Sneed A, Kowis C, Hodgson A, Muzny DM, McPherson J, Gibbs RA, Fahey J, Helton E, Ketteman M, Madan A, Rodrigues S, Sanchez A, Whiting M, Madari A, Young AC, Wetherby KD, Granite SJ, Kwong PN, Brinkley CP, Pearson RL, Bouffard GG, Blakesly RW, Green ED, Dickson MC, Rodriguez AC, Grimwood J, Schmutz J, Myers RM, Butterfield YS, Griffith M, Griffith OL, Krzywinski MI, Liao N, Morin R, Morrin R, Palmquist D, Petrescu AS, Skalska U, Smailus DE, Stott JM, Schnerch A, Schein JE, Jones SJ, Holt RA, Baross A, Marra MA, Clifton S, Makowski KA, Bosak S, Malek J and MGC Project Team

    The National Institutes of Health's Mammalian Gene Collection (MGC) project was designed to generate and sequence a publicly accessible cDNA resource containing a complete open reading frame (ORF) for every human and mouse gene. The project initially used a random strategy to select clones from a large number of cDNA libraries from diverse tissues. Candidate clones were chosen based on 5'-EST sequences, and then fully sequenced to high accuracy and analyzed by algorithms developed for this project. Currently, more than 11,000 human and 10,000 mouse genes are represented in MGC by at least one clone with a full ORF. The random selection approach is now reaching a saturation point, and a transition to protocols targeted at the missing transcripts is now required to complete the mouse and human collections. Comparison of the sequence of the MGC clones to reference genome sequences reveals that most cDNA clones are of very high sequence quality, although it is likely that some cDNAs may carry missense variants as a consequence of experimental artifact, such as PCR, cloning, or reverse transcriptase errors. Recently, a rat cDNA component was added to the project, and ongoing frog (Xenopus) and zebrafish (Danio) cDNA projects were expanded to take advantage of the high-throughput MGC pipeline.

    Funded by: PHS HHS: N01-C0-12400

    Genome research 2004;14;10B;2121-7

  • Synergistic control of keratinocyte adhesion through muscarinic and nicotinic acetylcholine receptor subtypes.

    Nguyen VT, Chernyavsky AI, Arredondo J, Bercovich D, Orr-Urtreger A, Vetter DE, Wess J, Beaudet AL, Kitajima Y and Grando SA

    Department of Dermatology, University of California, Davis, Sacramento, CA 95817, USA.

    The biological mechanisms involved in initiating, coordinating, and ultimately terminating cell-cell adhesion in the stratified epithelium are not well understood at present. This study was designed to elucidate the roles of the muscarinic M3, the nicotinic alpha3, and the mixed muscarinic-nicotinic alpha9 acetylcholine receptors in physiologic control of keratinocyte adhesion. Both muscarinic and nicotinic antagonists caused keratinocyte detachment and reversibly increased the permeability of keratinocyte monolayers, indicative of the involvement of both muscarinic and nicotinic pathways in the cholinergic control of keratinocyte adhesion. Since phosphorylation of adhesion proteins plays an important role in rapid assembly and disassembly of intercellular junctions, we measured muscarinic and nicotinic effects on phosphorylation of keratinocyte adhesion molecules. The phosphorylation levels of E-cadherin, beta-catenin, and gamma-catenin increased following pharmacological blockage of muscarinic receptors. Long-term blocking of alpha3, alpha9, and M3 receptor signaling pathways with antisense oligonucleotides resulted in cell-cell detachment and changes in the expression levels of E-cadherin, beta-catenin, and gamma-catenin in cultured human keratinocytes. Simultaneous inhibition of several receptor subtypes with a mixture of antisense oligonucleotides produced intensified abnormalities with cell adhesion. Moreover, altered cell-cell adhesion was found in the stratified epithelium of alpha3, alpha9, and M3 receptor knockout mice. Keratinocytes from these mice exhibited abnormal expression of adhesion molecules at both the protein and the mRNA levels. Thus, our data indicate that the alpha3, alpha9, and M3 acetylcholine receptors play key roles in regulating in a synergistic mode keratinocyte adhesion, most probably by modulating cadherin and catenin levels and activities. These findings may aid in the development of novel methods useful for the treatment of skin adhesion diseases and tumor metastasis.

    Funded by: NIDCR NIH HHS: DE14173; NIGMS NIH HHS: GM62136

    Experimental cell research 2004;294;2;534-49

  • Assessment of splice variant-specific functions of desmocollin 1 in the skin.

    Cheng X, Mihindukulasuriya K, Den Z, Kowalczyk AP, Calkins CC, Ishiko A, Shimizu A and Koch PJ

    Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.

    Desmocollin 1 (Dsc1) is part of a desmosomal cell adhesion receptor formed in terminally differentiating keratinocytes of stratified epithelia. The dsc1 gene encodes two proteins (Dsc1a and Dsc1b) that differ only with respect to their COOH-terminal cytoplasmic amino acid sequences. On the basis of in vitro experiments, it is thought that the Dsc1a variant is essential for assembly of the desmosomal plaque, a structure that connects desmosomes to the intermediate filament cytoskeleton of epithelial cells. We have generated mice that synthesize a truncated Dsc1 receptor that lacks both the Dsc1a- and Dsc1b-specific COOH-terminal domains. This mutant transmembrane receptor, which does not bind the common desmosomal plaque proteins plakoglobin and plakophilin 1, is integrated into functional desmosomes. Interestingly, our mutant mice did not show the epidermal fragility previously observed in dsc1-null mice. This suggests that neither the Dsc1a- nor the Dsc1b-specific COOH-terminal cytoplasmic domain is required for establishing and maintaining desmosomal adhesion. However, a comparison of our mutants with dsc1-null mice suggests that the Dsc1 extracellular domain is necessary to maintain structural integrity of the skin.

    Funded by: NIAMS NIH HHS: AR47343, R01 AR047343

    Molecular and cellular biology 2004;24;1;154-63

  • Wnk1 kinase deficiency lowers blood pressure in mice: a gene-trap screen to identify potential targets for therapeutic intervention.

    Zambrowicz BP, Abuin A, Ramirez-Solis R, Richter LJ, Piggott J, BeltrandelRio H, Buxton EC, Edwards J, Finch RA, Friddle CJ, Gupta A, Hansen G, Hu Y, Huang W, Jaing C, Key BW, Kipp P, Kohlhauff B, Ma ZQ, Markesich D, Payne R, Potter DG, Qian N, Shaw J, Schrick J, Shi ZZ, Sparks MJ, Van Sligtenhorst I, Vogel P, Walke W, Xu N, Zhu Q, Person C and Sands AT

    Lexicon Genetics, 8800 Technology Forest Place, The Woodlands, TX 77381, USA. brian@lexgen.com

    The availability of both the mouse and human genome sequences allows for the systematic discovery of human gene function through the use of the mouse as a model system. To accelerate the genetic determination of gene function, we have developed a sequence-tagged gene-trap library of >270,000 mouse embryonic stem cell clones representing mutations in approximately 60% of mammalian genes. Through the generation and phenotypic analysis of knockout mice from this resource, we are undertaking a functional screen to identify genes regulating physiological parameters such as blood pressure. As part of this screen, mice deficient for the Wnk1 kinase gene were generated and analyzed. Genetic studies in humans have shown that large intronic deletions in WNK1 lead to its overexpression and are responsible for pseudohypoaldosteronism type II, an autosomal dominant disorder characterized by hypertension, increased renal salt reabsorption, and impaired K+ and H+ excretion. Consistent with the human genetic studies, Wnk1 heterozygous mice displayed a significant decrease in blood pressure. Mice homozygous for the Wnk1 mutation died during embryonic development before day 13 of gestation. These results demonstrate that Wnk1 is a regulator of blood pressure critical for development and illustrate the utility of a functional screen driven by a sequence-based mutagenesis approach.

    Proceedings of the National Academy of Sciences of the United States of America 2003;100;24;14109-14

  • MAP kinases and mTOR mediate insulin-induced phosphorylation of insulin receptor substrate-1 on serine residues 307, 612 and 632.

    Gual P, Grémeaux T, Gonzalez T, Le Marchand-Brustel Y and Tanti JF

    INSERM U568 and IFR50, Faculté de Médecine, Nice Cedex 02, France.

    Insulin-induced IRS-1 serine phosphorylation could be physiologically important to regulate insulin action. In a hyperinsulinaemic state such as obesity or Type 2 diabetes, this phosphorylation could be modified and exacerbate insulin resistance. We aimed at identifying serine residues in IRS-1 phosphorylated in response to insulin stimulation and at determining the involved kinases.

    Methods: 3T3-L1 adipocytes, muscle and adipose tissue of mice were subjected to Western Blot analysis with phosphospecific antibodies to identify phosphorylation sites in IRS-1 following insulin treatment. Pharmacological inhibitors were used to determine the serine kinases involved in this phosphorylation.

    Results: In 3T3-L1 adipocytes, insulin promoted the phosphorylation of serine 307, 612 and 632 with Serine(612/632) more rapidly phosphorylated than Serine(307). Insulin-induced phosphorylation of Serine(307) was dependent on the activation of a PI 3-kinase/mTOR pathway. The phosphorylation of Serine(612/632) required the activation of the MAP kinase pathway following short-term insulin stimulation and activation of the PI 3-kinase/mTOR pathway following prolonged insulin stimulation. Phosphorylation of Serine(307) and Serine(632) occurred in vivo in skeletal muscle and white adipose tissue of mice injected with insulin and was dependent on the activation of mTOR. Moreover, inhibition of mTOR led to a persistent PI 3-kinase activation by insulin.

    Insulin-induced IRS-1 serine phosphorylation is a complex process involving different sites and kinases. This complexity could be physiologically important to accurately regulate insulin signalling. Abnormal phosphorylation of these serine residues in hyperinsulinaemic state could participate in the down-regulation of insulin signalling.

    Diabetologia 2003;46;11;1532-42

  • Plakoglobin is O-glycosylated close to the N-terminal destruction box.

    Hatsell S, Medina L, Merola J, Haltiwanger R and Cowin P

    Department of Cell Biology, New York University Medical School, New York, New York 10016, USA.

    Plakoglobin provides a key linkage in protein chains that connect desmosomal and classical cadherins to the cytoskeleton. It is also present in a significant cytosolic pool that has the capacity to impact on canonical Wnt signaling by competing for interaction with partner proteins of beta-catenin. The closely related protein, beta-catenin, is rapidly targeted for proteasomal degradation by phosphorylation of a "destruction box" within the N-terminal domain. Inhibition of this process forms the basis of Wnt signaling. This destruction box is also found in the N-terminal domain of plakoglobin. We report that plakoglobin is modified by the addition of O-GlcNAc at a single site in close proximity to the destruction box. O-GlcNAc modification has been proposed to counteract phosphorylation, provide protection from proteasomal degradation, mediate signal transduction, silence transcription, and regulate multimolecular protein assembly. This finding has potential implications for understanding the roles of plakoglobin.

    Funded by: NIGMS NIH HHS: GM47429

    The Journal of biological chemistry 2003;278;39;37745-52

  • The cell adhesion molecule M-cadherin is not essential for muscle development and regeneration.

    Hollnagel A, Grund C, Franke WW and Arnold HH

    Department of Cell and Molecular Biology, Institute of Biochemistry and Biotechnology, Technical University of Braunschweig, 38106 Braunschweig, Germany.

    M-cadherin is a classical calcium-dependent cell adhesion molecule that is highly expressed in developing skeletal muscle, satellite cells, and cerebellum. Based on its expression pattern and observations in cell culture, it has been postulated that M-cadherin may be important for the fusion of myoblasts to form myotubes, the correct localization and function of satellite cells during muscle regeneration, and the specialized architecture of adhering junctions in granule cells of cerebellar glomeruli. In order to investigate the potential roles of M-cadherin in vivo, we generated a null mutation in mice. Mutant mice were viable and fertile and showed no gross developmental defects. In particular, the skeletal musculature appeared essentially normal. Moreover, muscle lesions induced by necrosis were efficiently repaired in mutant mice, suggesting that satellite cells are present, can be activated, and are able to form new myofibers. This was also confirmed by normal growth and fusion potential of mutant satellite cells cultured in vitro. In the cerebellum of M-cadherin-lacking mutants, typical contactus adherens junctions were present and similar in size and numbers to the equivalent junctions in wild-type animals. However, the adhesion plaques in the cerebellum of these mutants appeared to contain elevated levels of N-cadherin compared to wild-type animals. Taken together, these observations suggest that M-cadherin in the mouse serves no absolutely required function during muscle development and regeneration and is not essential for the formation of specialized cell contacts in the cerebellum. It seems that N-cadherin or other cadherins can largely compensate for the lack of M-cadherin.

    Molecular and cellular biology 2002;22;13;4760-70

  • Regulation of cadherin junctions during mouse submandibular gland development.

    Menko AS, Zhang L, Schiano F, Kreidberg JA and Kukuruzinska MA

    Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.

    Submandibular gland (SMG) development involves branching morphogenesis of the salivary epithelium into the surrounding mesenchyme, accompanied by proliferation and differentiation of immature salivary cells along acinar and ductal cell lineages. During development, salivary cell sorting and cell-cell adhesion are likely to be directed by cadherin adhesion receptors. We show that two classic cadherins, N- and E-cadherin, participate in SMG development. Early in embryonic morphogenesis, both cadherins displayed diffuse staining with regionalized localization to cell-cell borders. At this stage, significant pools of N- and E-cadherins were Triton-soluble, suggesting that fractions of these molecules were not localized to stable junctional complexes associated with the actin cytoskeleton. With cytodifferentiation, cadherins became progressively Triton-insoluble, and this correlated with their organization at cell-cell interfaces. In the cytodifferentiated SMG, N-cadherin was absent, whereas E-cadherin remained at cell-cell interfaces. Early in morphogenesis, beta-catenin was also primarily Triton-soluble, and its association with the actin cytoskeleton and localization to the adherens junctions increased with cytodifferentiation. Greater recruitment of cadherins and beta-catenin to cell-cell borders was paralleled by changes in membrane association of two Rho GTPases, Cdc42 and RhoA. N-cadherin was detected only at early stages of postnatal development, whereas E-cadherin and beta-catenin became progressively Triton-insoluble during differentiation. Our results indicate that N-cadherin functions transiently in SMG development. On the other hand, E-cadherin and beta-catenin appear to play different roles during tissue organization and cytodifferentiation. In early morphogenesis, E-cadherin and beta-catenin are likely to participate in SMG remodeling, whereas during cytodifferentiation, they form stable cell-cell contacts, and may collaborate with Rho GTPases in the establishment and maintenance of salivary cell polarity.

    Funded by: NIDCR NIH HHS: DE10183

    Developmental dynamics : an official publication of the American Association of Anatomists 2002;224;3;321-33

  • Asymmetrical morphogenesis and medio-lateral positioning of molars during mouse development.

    Cam Y, Fausser JL, Vonesch JL, Peterkova R, Peterka M, Halaskova M and Lesot H

    INSERM Unit 424, Institut de Biologie Médicale, Faculté de Médecine de l'Université Louis Pasteur, Strasbourg, France. Yves.Cam@odonto-ulp.u.strasbg.fr

    The functionality of the dentition depends on occlusal relationships between opposing crown surfaces. To investigate the relative changes in positioning of upper and lower molar germs during mouse development, we used serial histological sections of late day 13 (embryonic day (ED)13.5) to early day 18 (ED18) foetus heads and performed computer-aided 3D reconstructions. From ED13.5 to ED15.5. the first lower molar (M1) got a less medial position relative to its upper counterpart (M1); superimposition progressed postero-anteriorly. From ED14.5, the apparent medial displacement of M(1) vs. M1 was partly due to the asymmetrical growth of the M(1) to give rise to the lingual row of cusps, conspicuous at ED17. The superimposition of M(2)/M2 along the medio-lateral axis was observed from their bud stage (ED14.5), and the one of M(1)/M1 was almost complete at ED15.5. However, this was not the final position. as at ED 18, M1 and M2 had a more lateral location than their upper counterparts. Immunostaining showed that differential expression of antigens associated to desmosomes but not to adherens junctions might be involved in the asymmetrical development of M(1) thus contributing to the relative medio-lateral positioning of the first molars at early stages.

    European journal of oral sciences 2002;110;1;35-43

  • Desmoplakin is essential in epidermal sheet formation.

    Vasioukhin V, Bowers E, Bauer C, Degenstein L and Fuchs E

    Department of Molecular Genetics and Cell Biology, Howard Hughes Medical Institute, The University of Chicago, Chicago, Illinois 60637, USA.

    We have generated an epidermis-specific desmoplakin (DP) mouse knockout, and show that epidermal integrity requires DP; mechanical stresses to DP-null skin cause intercellular separations. The number of epidermal desmosomes in DP-null skin is similar to wild type (WT), but they lack keratin filaments, which compromise their function. DP-null keratinocytes have few desmosomes in vitro, and are unable to undergo actin reorganization and membrane sealing during epithelial sheet formation. Adherens junctions are also reduced. In vitro, DP transgene expression rescues these defects. DP is therefore required for assembly of functional desmosomes, maintaining cytoskeletal architecture and reinforcing membrane attachments essential for stable intercellular adhesion.

    Funded by: NIAMS NIH HHS: R01-AR27883

    Nature cell biology 2001;3;12;1076-85

  • Cell-matrix interactions and cell-cell junctions during epithelial histo-morphogenesis in the developing mouse incisor.

    Kieffer-Combeau S, Meyer JM and Lesot H

    INSERM U424, Institut de Biologie Médicale, Faculté de Médecine, Strasbourg, France.

    The continuously growing rodent incisor develops mainly along its antero-posterior axis. The labio-lingual asymmetry which characterizes this tooth is initiated at the cap stage and increases further during the cap to bell transition (ED14 to ED16) when histogenesis of the enamel organ proceeds. Histology, transmission electron microscopy (TEM), and immunostaining were used to document the changes in the basement membrane (BM) as well as the modifications of epithelial cell-matrix and cell-cell interactions during this period. The expression of plakoglobin, desmoglein and E-cadherin at ED14 suggested that the main cell-cell junctional complexes were adherens junctions. The expression of desmoglein and TEM observations suggested a progressive antero-posterior stabilization of the enamel organ by means of desmosomes from ED14 to ED18. alpha6 integrin, BP 230 and laminin gamma2 chain were all expressed in the developing incisor but were not always co-distributed. Immunostaining and TEM suggested that only primitive type II hemidesmosomes were present. At ED14, cells of the enamel knot (EK) did not show any specific expression for antigens involved in cell-cell interaction. However, strong staining for the laminin gamma2 chain characterized the BM in contact with EK cells. The BM in the labial part of the cervical loop demonstrated ultrastructural changes: the presence of loops of the lamina densa in this region preceeded the differential expression of the integrin alpha6 subunit and that of the laminin gamma2 chain in the labial/lingual parts of the cervical loop. Apoptosis was transiently observed in the contiguous mesenchyme. This affected osteoblasts and also nerve cells close to the labial part of the cervical loop.

    The International journal of developmental biology 2001;45;5-6;733-42

  • Construction of long-transcript enriched cDNA libraries from submicrogram amounts of total RNAs by a universal PCR amplification method.

    Piao Y, Ko NT, Lim MK and Ko MS

    Developmental Genomics and Aging Section, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA.

    Here we report a novel design of linker primer that allows one to differentially amplify long tracts (average 3.0 kb with size ranges of 1-7 kb) or short DNAs (average 1.5 kb with size ranges of 0.5-3 kb) from a complex mixture. The method allows one to generate cDNA libraries enriched for long transcripts without size selection of insert DNAs. One representative library from newborn kidney includes 70% of clones bearing ATG start codons. A comparable library has been generated from 20 mouse blastocysts, containing only approximately 40 ng of total RNA. This universal PCR amplification scheme can provide a route to isolate very large cDNAs, even if they are expressed at very low levels.

    Genome research 2001;11;9;1553-8

  • beta-Catenin controls hair follicle morphogenesis and stem cell differentiation in the skin.

    Huelsken J, Vogel R, Erdmann B, Cotsarelis G and Birchmeier W

    Max-Delbrueck-Center for Molecular Medicine, Robert-Roessle-Strasse 10, 13092, Berlin, Germany.

    beta-Catenin is an essential molecule in Wnt/wingless signaling, which controls decisive steps in embryogenesis. To study the role of beta-catenin in skin development, we introduced a conditional mutation of the gene in the epidermis and hair follicles using Cre/loxP technology. When beta-catenin is mutated during embryogenesis, formation of placodes that generate hair follicles is blocked. We show that beta-catenin is required genetically downstream of tabby/downless and upstream of bmp and shh in placode formation. If beta-catenin is deleted after hair follicles have formed, hair is completely lost after the first hair cycle. Further analysis demonstrates that beta-catenin is essential for fate decisions of skin stem cells: in the absence of beta-catenin, stem cells fail to differentiate into follicular keratinocytes, but instead adopt an epidermal fate.

    Cell 2001;105;4;533-45

  • Adult mice deficient in actinin-associated LIM-domain protein reveal a developmental pathway for right ventricular cardiomyopathy.

    Pashmforoush M, Pomiès P, Peterson KL, Kubalak S, Ross J, Hefti A, Aebi U, Beckerle MC and Chien KR

    UCSD-Salk Program in Molecular Medicine and the UCSD Institute of Molecular Medicine, University of California at San Diego, La Jolla, California, USA.

    Although cytoskeletal mutations are known causes of genetically based forms of dilated cardiomyopathy, the pathways that link these defects with cardiomyopathy are unclear. Here we report that the alpha-actinin-associated LIM protein (ALP; Alp in mice) has an essential role in the embryonic development of the right ventricular (RV) chamber during its exposure to high biomechanical workloads in utero. Disruption of the gene encoding Alp (Alp) is associated with RV chamber dilation and dysfunction, directly implicating alpha-actinin-associated proteins in the onset of cardiomyopathy. In vitro assays showed that Alp directly enhances the capacity of alpha-actinin to cross-link actin filaments, indicating that the loss of Alp function contributes to destabilization of actin anchorage sites in cardiac muscle. Alp also colocalizes at the intercalated disc with alpha-actinin and gamma-catenin, the latter being a known disease gene for human RV dysplasia. Taken together, these studies point to a novel developmental pathway for RV dilated cardiomyopathy via instability of alpha-actinin complexes.

    Nature medicine 2001;7;5;591-7

  • BAC contig from a 3-cM region of mouse chromosome 11 surrounding Brca1.

    Pershouse M, Li J, Yang C, Su H, Brundage E, Di W, Biggs PJ, Bradley A and Chinault AC

    Department of Molecular and Human Genetics, Howard Hughes Medical Institute, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.

    Even with the completion of a draft version of the human genome sequence only a fraction of the genes identified from this sequence have known functions. Chromosomal engineering in mouse cells, in concert with gene replacement assays to prove the functional significance of a given genomic region or gene, represents a rapid and productive means for understanding the role of a given set of genes. Both techniques rely heavily on detailed maps of chromosomal regions, initially to understand the scope of the regions being modified and finally to provide the cloned resources necessary to allow both finished sequencing and large insert complementation. This report describes the creation of a BAC clone contig on mouse chromosome 11 in a region showing conservation of synteny with sequences on human chromosome 17. We have created a detailed map of an approximately 3-cM region containing at least 33 genes through the use of multiple BAC mapping strategies, including chromosome walking and multiplex oligonucleotide hybridization and gap filling. The region described is one of the targets of a large effort to create a series of mice with regional deletions on mouse chromosome 11 (33-80 cM) that can subsequently be subjected to further mutagenesis.

    Funded by: NCI NIH HHS: CA75719

    Genomics 2000;69;1;139-42

  • Genome-wide expression profiling of mid-gestation placenta and embryo using a 15,000 mouse developmental cDNA microarray.

    Tanaka TS, Jaradat SA, Lim MK, Kargul GJ, Wang X, Grahovac MJ, Pantano S, Sano Y, Piao Y, Nagaraja R, Doi H, Wood WH, Becker KG and Ko MS

    Laboratory of Genetics and DNA Array Unit, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224-6820, USA.

    cDNA microarray technology has been increasingly used to monitor global gene expression patterns in various tissues and cell types. However, applications to mammalian development have been hampered by the lack of appropriate cDNA collections, particularly for early developmental stages. To overcome this problem, a PCR-based cDNA library construction method was used to derive 52,374 expressed sequence tags from pre- and peri-implantation embryos, embryonic day (E) 12.5 female gonad/mesonephros, and newborn ovary. From these cDNA collections, a microarray representing 15,264 unique genes (78% novel and 22% known) was assembled. In initial applications, the divergence of placental and embryonic gene expression profiles was assessed. At stage E12.5 of development, based on triplicate experiments, 720 genes (6.5%) displayed statistically significant differences in expression between placenta and embryo. Among 289 more highly expressed in placenta, 61 placenta-specific genes encoded, for example, a novel prolactin-like protein. The number of genes highly expressed (and frequently specific) for placenta has thereby been increased 5-fold over the total previously reported, illustrating the potential of the microarrays for tissue-specific gene discovery and analysis of mammalian developmental programs.

    Proceedings of the National Academy of Sciences of the United States of America 2000;97;16;9127-32

  • Plakoglobin suppresses epithelial proliferation and hair growth in vivo.

    Charpentier E, Lavker RM, Acquista E and Cowin P

    Departments of Cell Biology and Dermatology, New York University Medical School, New York 10016, USA.

    Plakoglobin regulates cell adhesion by providing a modulatable connection between both classical and desmosomal cadherins and their respective cytoskeletal linker proteins. Both plakoglobin and the related protein beta-catenin are posttranscriptionally upregulated in response to Wnt-1 in cultured cells. Upregulation of beta-catenin has been implicated in potentiating hyperproliferation and tumor formation. To investigate the role of plakoglobin in these functions we expressed a full-length (PG) and an NH(2)-terminally truncated form of plakoglobin (DeltaN80PG) in mouse epidermis and hair follicles, tissues which undergo continuous and easily observed postnatal renewal and remodeling. Expression of these constructs results in stunted hair growth, a phenotype that has also been observed in transgenic mice expressing Wnt3 and Dvl2 (Millar et al. 1999). Hair follicles from PG and DeltaN80PG mice show premature termination of the growth phase (anagen) of the hair cycle, an event that is regulated in part by FGF5 (Hebert et al. 1994). The proliferative rate of the epidermal cells was reduced and apoptotic changes, which are associated with entry into the regressive phase of the hair follicle cycle (catagen), occurred earlier than usual.

    Funded by: NIGMS NIH HHS: GM47429

    The Journal of cell biology 2000;149;2;503-20

  • Requirement for beta-catenin in anterior-posterior axis formation in mice.

    Huelsken J, Vogel R, Brinkmann V, Erdmann B, Birchmeier C and Birchmeier W

    Max-Delbrueck-Center for Molecular Medicine, 13125 Berlin, Germany.

    The anterior-posterior axis of the mouse embryo is defined before formation of the primitive streak, and axis specification and subsequent anterior development involves signaling from both embryonic ectoderm and visceral endoderm. Tauhe Wnt signaling pathway is essential for various developmental processes, but a role in anterior-posterior axis formation in the mouse has not been previously established. Beta-catenin is a central player in the Wnt pathway and in cadherin-mediated cell adhesion. We generated beta-catenin-deficient mouse embryos and observed a defect in anterior-posterior axis formation at embryonic day 5.5, as visualized by the absence of Hex and Hesx1 and the mislocation of cerberus-like and Lim1 expression. Subsequently, no mesoderm and head structures are generated. Intercellular adhesion is maintained since plakoglobin substitutes for beta-catenin. Our data demonstrate that beta-catenin function is essential in anterior-posterior axis formation in the mouse, and experiments with chimeric embryos show that this function is required in the embryonic ectoderm.

    The Journal of cell biology 2000;148;3;567-78

  • The genomic organization of type I keratin genes in mice.

    Sato H, Koide T, Sagai T, Ishiguro SI, Tamai M, Saitou N and Shiroishi T

    Department of Ophthalmology, Tohoku University School of Medicine, Seiryo-Machi 1-1, Sendai, 980-8574, Japan.

    We isolated two new keratin cDNAs by screening a cDNA library constructed from poly(A)+ RNA of the dorsal and abdominal skin of C57BL/10J mice with a probe of human KRT14. Due to its high sequence homology to human keratin 17 cDNA, one full-length cDNA is most likely to be mouse keratin 17 (Krt1-17) cDNA. The other is the putative full-length cDNA of a novel type I keratin gene, designated Krt1-c29. These two keratin genes were mapped to the distal portion of Chromosome 11, where the mouse keratin gene complex-1 (Krt1) is localized. To elucidate the genomic organization of Krt1 in mice, we carried out genetic and physical analyses of Krt1. A large-scale linkage analysis using intersubspecific backcrosses suggested that there are two major clusters in Krt1, one containing Krt1-c29, Krt1-10, and Krt1-12 and the other containing Krt1-14, -15, -17, and -19. Truncation experiments with two yeast artificial chromosome clones containing the two clusters above have revealed that the gene order of Krt1 is centromere-Krt1-c29-Krt1-10-Krt1-12-Krt1-13-K rt1-15-Krt1-19-Krt1-14-K rt1-17-telomere. Finally, we analyzed sequence divergence between the genes belonging to the Krt1 complex. The results clearly indicated that genes are classified into two major groups with respect to phylogenetic relationship. Each group consists of the respective gene cluster demonstrated by genetic and physical analyses in this study, suggesting that the physical organization of the Krt1 complex reflects the evolutionary process of gene duplication of this complex.

    Genomics 1999;56;3;303-9

  • Desmosomal localization of beta-catenin in the skin of plakoglobin null-mutant mice.

    Bierkamp C, Schwarz H, Huber O and Kemler R

    Max Planck Institute of Immunobiology, Department of Molecular Embryology, Stübeweg 51, D-79108 Freiburg and Max Planck Institute of Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany.

    Plakoglobin, a protein belonging to the Armadillo-repeat gene family, is the only component that adherens junctions and desmosomes have in common. Plakoglobin null-mutant mouse embryos die because of severe heart defects and may exhibit an additional skin phenotype, depending on the genetic background. Lack of plakoglobin affects the number and structure of desmosomes, resulting in visible defects when cells are subjected to increasing mechanical stress, e.g. when embryonic blood starts circulating or during skin differentiation. By analysing plakoglobin-negative embryonic skin differentiation in more detail, we show here that, in the absence of plakoglobin, its closest homologue, beta-catenin, becomes localized to desmosomes and associated with desmoglein. This substitution may account for the relatively late appearance of the developmental defects seen in plakoglobin null-mutant embryos. beta-catenin cannot, however, fully compensate a lack of plakoglobin. In the absence of plakoglobin, there was reduced cell-cell adhesion, resulting in large intercellular spaces between keratinocytes, subcorneal acantholysis and necrosis in the granular layer of the skin. Electron microscopic analysis documented a reduced number of desmosomes, and those present lacked the inner dense plaque and had fewer keratin filaments anchored. Our analysis underlines the central role of plakoglobin for desmosomal assembly and function during embryogenesis.

    Development (Cambridge, England) 1999;126;2;371-81

  • Desmoplakin is required early in development for assembly of desmosomes and cytoskeletal linkage.

    Gallicano GI, Kouklis P, Bauer C, Yin M, Vasioukhin V, Degenstein L and Fuchs E

    Howard Hughes Medical Institute and Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago Illinois 60637, USA.

    Desmosomes first assemble in the E3.5 mouse trophectoderm, concomitant with establishment of epithelial polarity and appearance of a blastocoel cavity. Throughout development, they increase in size and number and are especially abundant in epidermis and heart muscle. Desmosomes mediate cell-cell adhesion through desmosomal cadherins, which differ from classical cadherins in their attachments to intermediate filaments (IFs), rather than actin filaments. Of the proteins implicated in making this IF connection, only desmoplakin (DP) is both exclusive to and ubiquitous among desmosomes. To explore its function and importance to tissue integrity, we ablated the desmoplakin gene. Homozygous -/- mutant embryos proceeded through implantation, but did not survive beyond E6.5. Surprisingly, analysis of these embryos revealed a critical role for desmoplakin not only in anchoring IFs to desmosomes, but also in desmosome assembly and/or stabilization. This finding not only unveiled a new function for desmoplakin, but also provided the first opportunity to explore desmosome function during embryogenesis. While a blastocoel cavity formed and epithelial cell polarity was at least partially established in the DP (-/-) embryos, the paucity of desmosomal cell-cell junctions severely affected the modeling of tissue architecture and shaping of the early embryo.

    The Journal of cell biology 1998;143;7;2009-22

  • Localization of antigens associated with adherens junctions, desmosomes, and hemidesmosomes during murine molar morphogenesis.

    Fausser JL, Schlepp O, Aberdam D, Meneguzzi G, Ruch JV and Lesot H

    INSERM U.424, Institut de Biologie Médicale, Faculté de Médecine, Strasbourg, France.

    Epitheliomesenchymal interactions are known to play a crucial role during odontogenesis. Since epithelial cell-cell and cell-matrix interactions may also be involved in enamel organ histomorphogenesis, we investigated the localization of proteins associated with junctional complexes in mouse and rat first lower molars by indirect immunofluorescence. Adherens junctions were detected using antibodies directed against E-cadherin, beta-catenin, and plakoglobin (gamma-catenin). Desmosomes were localized with antibodies against desmoglein, and hemidesmosomes using antibodies against BP-230 and HD-1 proteins. When the inner dental epithelium differentiates, a decrease of E-cadherin, plakoglobin, and BP-230 is seen. An asymmetric distribution of plakoglobin, desmoglein, and BP-230 between the lateral and medial side of the tooth exists; desmoglein, which was first restricted to the gubernaculum dentis, progressively accumulated in the stellate reticulum, the stratum intermedium, and the basal pole of ameloblasts. The specific temporospatial distributions patterns of these antigens suggests a direct involvement of adherens junctions, desmosomes, and hemidesmosomes in the development of the murine first lower molar.

    Differentiation; research in biological diversity 1998;63;1;1-11

  • Distinct location and prevalence of alpha-, beta-catenins and gamma-catenin/plakoglobin in developing and denervated skeletal muscle.

    Cifuentes-Diaz C, Goudou D, Mège RM, Velasco E, Nicolet M, Herrenknecht K, Rubin L and Rieger F

    INSERM, Neuromodulations Interactireset Neurophathologies, Paris, France.

    We studied the distribution of alpha-catenin, beta-catenin and gamma-catenin/plakoglobin in developing, adult and denervated mouse skeletal muscle. During primary myogenesis, all three catenins present a subsarcolemmal distribution within primary myotubes. During secondary myogenesis they accumulate at myotube-myotube contacts. In contrast to the other catenins, gamma-catenin is strongly expressed in the sarcoplasm. In adult muscle, all three catenins are localized on the presynaptic elements of the neuromuscular junction. In denervated muscles, alpha- and beta-catenins are upregulated like N- and M-cadherin, while the levels of gamma-catenin/plakoglobin remain unchanged. The developmental changes in localization and regulation of alpha- and beta-catenins in muscle compared to gamma-catenin/plakoglobin are suggestive of a privileged association of alpha- and beta-catenins with N- and M-cadherins, while gamma-catenin/plakoglobin appears to be expressed quite independently and must assume a different role during myogenesis.

    Cell adhesion and communication 1998;5;2;161-76

  • A new mutation Rim3 resembling Re(den) is mapped close to retinoic acid receptor alpha (Rara) gene on mouse chromosome 11.

    Sato H, Koide T, Masuya H, Wakana S, Sagai T, Umezawa A, Ishiguro S, Tamai M, Shiroishi T and Tama M

    Department of Ophthalmology, Tohoku University School of Medicine, Miyagi-ken, Japan.

    A new mouse mutation, recombination-induced mutation 3 (Rim3), arose spontaneously in our mouse facility. This mutation exhibits corneal opacity as well as abnormal skin and hair development resembling rex denuded (Re(den)) and bareskin (Bsk). Large-scale linkage analysis with two kinds of intersubspecific backcrosses revealed that Rim3 is mapped to the distal portion of Chromosome (Chr) 11, in which Re(den) and Bsk have been located, and is very close to the retinoic acid receptor, alpha (Rara). The genes, keratin gene complex-1, acidic, gene 10, 12 (Krt1-10, 12), granulin (Grn), junctional plakoglobin (Jup) and Rara, all of which regulate growth and differentiation of epithelial cells, are genetically excluded as candidate genes for Rim3, but are clustered in the short segment on mouse Chr 11.

    Mammalian genome : official journal of the International Mammalian Genome Society 1998;9;1;20-5

  • Cell-junctional and cytoskeletal organization in mouse blastocysts lacking E-cadherin.

    Ohsugi M, Larue L, Schwarz H and Kemler R

    Max-Planck-Institut für Immunbiologie, Freiburg, Germany.

    Trophectoderm epithelium formation, the first visible differentiation process during mouse embryonic development, is affected in embryos lacking the cell adhesion molecule E-cadherin. Here we analyze the developmental potential of such E-cadherin-negative embryos, focusing on the organization of cell junctions and the cytoskeleton. To do this we used antibodies directed against alpha-, beta-, or gamma-(plakoglobin)-catenin and junctional and cytoskeletal proteins including ZO-1 and occludin (tight junctions), desmoglein1 (desmosomes), connexin43 (gap junctions), and EndoA (cytokeratin intermediate filaments). Membrane localization of alpha- and beta-catenin, and ZO-1, as well as cortical actin filament organization were abnormal in E-cadherin-negative embryos, and the expression levels of alpha- and beta-catenin were dramatically reduced, all suggesting a regulatory role for E-cadherin in forming the cadherin-catenin complex. In contrast, the membrane localization of plakoglobin, occludin, desmoglein1, connexin43, and cytokeratin filaments appeared unaltered. The unusual morphogenesis in E-cadherin-negative embryos apparently reflects defects in the molecular architecture of a supermolecular assembly involving zonulae adherens, tight junctions, and cortical actin filament organization, although the individual structures still appeared normal in electron microscopical analysis.

    Developmental biology 1997;185;2;261-71

  • Embryonic heart and skin defects in mice lacking plakoglobin.

    Bierkamp C, Mclaughlin KJ, Schwarz H, Huber O and Kemler R

    Department of Molecular Embryology, Max Planck Institute for Immunobiology, Stübeweg 51, Freiburg, D-79108, Germany. kemler@immunbio.mpg.de

    Plakoglobin is the only component common to both the desmosomal plaque and the cadherin-catenin cell adhesion complex in the adherens junction. It is highly homologous to vertebrate beta-catenin and to Drosophila armadillo protein and may-like these proteins-be also involved in signaling pathways. To analyze the role of plakoglobin during mouse development we inactivated the plakoglobin gene by homologous recombination in embryonic stem cells and generated transgenic mice. Plakoglobin null-mutant embryos died from Embryonic Day 10.5 onward, due to severe heart defects. Some mutant embryos developed further, especially on a C57BL/6 genetic background, and died around birth, presumably due to cardiac dysfunction, and with skin blistering and subcorneal acantholysis. Ultrastructural analysis revealed that here desmosomes were greatly reduced in number and structurally altered. Thus, using reversed genetics we demonstrate that plakoglobin is an essential structural component for desmosome function. The skin phenotype in plakoglobin-deficient mice is reminiscent of the human blistering disease, epidermolytic hyperkeratosis.

    Developmental biology 1996;180;2;780-5

  • Targeted mutation of plakoglobin in mice reveals essential functions of desmosomes in the embryonic heart.

    Ruiz P, Brinkmann V, Ledermann B, Behrend M, Grund C, Thalhammer C, Vogel F, Birchmeier C, Günthert U, Franke WW and Birchmeier W

    Max-Delbruck-Center for Molecular Medicine, Berlin, Germany.

    Plakoglobin (gamma-catenin), a member of the armadillo family of proteins, is a constituent of the cytoplasmic plaque of desmosomes as well as of other adhering cell junctions, and is involved in anchorage of cytoskeletal filaments to specific cadherins. We have generated a null mutation of the plakoglobin gene in mice. Homozygous -/- mutant animals die between days 12-16 of embryogenesis due to defects in heart function. Often, heart ventricles burst and blood floods the pericard. This tissue instability correlates with the absence of desmosomes in heart, but not in epithelia organs. Instead, extended adherens junctions are formed in the heart, which contain desmosomal proteins, i.e., desmoplakin. Thus, plakoglobin is an essential component of myocardiac desmosomes and seems to play a crucial role in the sorting out of desmosomal and adherens junction components, and consequently in the architecture of intercalated discs and the stabilization of heart tissue.

    The Journal of cell biology 1996;135;1;215-25

  • Expression and cell membrane localization of catenins during mouse preimplantation development.

    Ohsugi M, Hwang SY, Butz S, Knowles BB, Solter D and Kemler R

    Max-Planck-Institut für Immunbiologie, Freiburg, Federal Republic of Germany.

    We have studied transcription, expression, and membrane localization of components of the E-cadherin-catenin complex stage by stage during mouse preimplantation development. Maternal E-cadherin and alpha- and beta-catenin are stored as mRNA and/or protein in unfertilized eggs and are already assembled into a protein complex at this stage. After fertilization, it is likely that they mediate adhesion of early-stage blastomeres. Biosynthesis of plakoglobin is delayed relative to the other components. The temporal mRNA and protein expression patterns of the components of the cadherin-catenin complex correlate with the presence or absence of potential cytoplasmic polyadenylation elements (CPEs) in the 3'-UTRs of the respective cDNAs. Our results suggest that the components of the E-cadherin-catenin complex derived from both maternal and zygotic gene activity are increasingly accumulated and stored in a nonfunctional form during early cleavage stages and are ready to be used for compaction and the formation of the trophectodermal cell layer.

    Funded by: NCI NIH HHS: CA 34196, CA 37725

    Developmental dynamics : an official publication of the American Association of Anatomists 1996;206;4;391-402

  • Expression of catenins during mouse embryonic development and in adult tissues.

    Butz S and Larue L

    Max-Planck-Institut für Immunbiologie, Freiburg, Germany.

    Classical cadherins are cell-surface glycoproteins that mediate calcium-dependent cell adhesion. The cytoplasmic domain of these glycoproteins is linked to the cytoskeleton through the catenins (alpha, beta and gamma). The catenins are intracellular polypeptides that are part of a complex sub-membranous network modulating the adhesive ability of the cells. One approach to elucidate the role of these molecules in the cell is to investigate their distribution during mouse development and in adult tissues. This study reports that catenins are widely expressed but in varying amounts in embryos and adult tissues. The expression of all three catenins is most prominent in the adult heart muscle and in epithelia of all developmental stages. In other embryonic and adult tissues, lower expression of catenins was detected, e.g., in smooth muscle or connective tissue. Catenins are coexpressed with various cadherins in different tissues. Gastrulation is the first time during embryogenesis when a discrepancy occurs between the expression of catenins and E-cadherin. E-cadherin expression is suppressed in mesodermal cells but not the expression of catenins. This discrepancy suggests that another cadherin may interact with catenins. Similarly, E-cadherin is generally expressed in adult liver but not in the regions surrounding the central veins. In contrast, catenins are uniformly expressed in the liver, suggesting that they are associated with other cadherins in E-cadherin negative cells. Finally, the three catenins are not always concurrently expressed. For example, in peripheral nerves, only beta-catenin is observable, and in smooth muscle plakoglobin is not detectable.

    Cell adhesion and communication 1995;3;4;337-52

  • Lack of beta-catenin affects mouse development at gastrulation.

    Haegel H, Larue L, Ohsugi M, Fedorov L, Herrenknecht K and Kemler R

    Max-Planck-Institut für Immunbiologie, Freiburg, Germany.

    Molecular analysis of the cadherin-catenin complex elucidated the central role of beta-catenin in this adhesion complex, as it binds to the cytoplasmic domain of E-cadherin and to alpha-catenin. beta-Catenin may also function in signalling pathways, given its homology to the gene product of the Drosophila segment polarity gene armadillo, which is known to be involved in the wingless signalling cascade. To study the function of beta-catenin during mouse development, gene knock-out experiments were performed in embryonic stem cells and transgenic mice were generated. beta-Catenin null-mutant embryos formed blastocysts, implanted and developed into egg-cylinder-stage embryos. At day 7 post coitum, the development of the embryonic ectoderm was affected in mutant embryos. Cells detached from the ectodermal cell layer and were dispersed into the proamniotic cavity. No mesoderm formation was observed in mutant embryos. The development of extraembryonic structures appeared less dramatically or not at all affected. Our results demonstrate that, although beta-catenin is expressed rather ubiquitously, it is specifically required in the ectodermal cell layer.

    Development (Cambridge, England) 1995;121;11;3529-37

  • Isolation of novel tissue-specific genes from cDNA libraries representing the individual tissue constituents of the gastrulating mouse embryo.

    Harrison SM, Dunwoodie SL, Arkell RM, Lehrach H and Beddington RS

    National Institute for Medical Research, London, UK.

    A total of 5 conventional, directionally cloned plasmid cDNA libraries have been constructed from the entire embryonic region of the mid-gastrulation mouse embryo and from its four principal tissue constituents (ectoderm, mesoderm, endoderm and primitive streak). These libraries have been validated with respect to the number of independent clones, insert-size and appropriate representation of diagnostic marker genes. Subtractive hybridisation has been used to remove clones common to the Endoderm and Mesoderm cDNA libraries resulting in an Endoderm minus Mesoderm subtracted library. Probe prepared from this subtracted library has been hybridised to a grid containing approximately 18,500 Embryonic Region library clones. Three novel clones have been recovered as well as expected genes already known to be highly expressed in the primitive endoderm lineage at this stage of development. In situ hybridisation to early postimplantation embryos has revealed the expression patterns of these novel genes. One is highly expressed exclusively in visceral endoderm, one is expressed in ectodermal and endodermal tissues, and the third proves to be an early marker of prospective and differentiated surface ectoderm as well as being expressed in endoderm and its derivatives.

    Development (Cambridge, England) 1995;121;8;2479-89

  • The human plakoglobin gene localizes on chromosome 17q21 and is subjected to loss of heterozygosity in breast and ovarian cancers.

    Aberle H, Bierkamp C, Torchard D, Serova O, Wagner T, Natt E, Wirsching J, Heidkämper C, Montagna M, Lynch HT et al.

    Max-Planck-Institut für Immunobiologie, Freiburg, Germany.

    The gene encoding human plakoglobin was mapped to chromosome 17q12-q22. An intragenic restriction fragment length polymorphism was used to localize the plakoglobin gene distal to locus KRT10 and proximal to the marker D17S858. The plakoglobin gene colocalizes with the polymorphic 17q21 marker UM8 on the same cosmid insert. This subregion of chromosome 17 is known to be particularly subjected to genetic alterations in sporadic breast and ovarian tumors. We show loss of heterozygosity of the plakoglobin gene in breast and ovarian tumors. We have identified a low-frequency polymorphism in the plakoglobin coding sequence which results in an arginine to histidine substitution at amino acid position 142 of the protein, as well as a silent mutation at nucleotide position 332 of the coding sequence. This polymorphism allowed us to demonstrate an allelic association of plakoglobin with predisposition to familial breast and ovarian cancers. Our results, together with the present knowledge about the biological function of plakoglobin, suggest that plakoglobin might represent a putative tumor suppressor gene for breast and ovarian cancers.

    Proceedings of the National Academy of Sciences of the United States of America 1995;92;14;6384-8

  • The genes coding for alpha and beta catenin (Catna1 and Catnb) and plakoglobin (Jup) map to mouse chromosomes 18, 9, and 11, respectively.

    Guénet JL, Simon-Chazottes D, Ringwald M and Kemler R

    Unité de Génétique des Mammifères de l'Institut Pasteur, Paris, France.

    Mammalian genome : official journal of the International Mammalian Genome Society 1995;6;5;363-6

  • Distinct cadherin-catenin complexes in Ca(2+)-dependent cell-cell adhesion.

    Butz S and Kemler R

    Max-Planck-Institut für Immunbiologie, Freiburg, Germany.

    Catenins are peripheral cytoplasmic proteins originally identified in association with the mouse epithelial cell adhesion molecule E-cadherin. Molecular cloning and primary structure analysis demonstrated that alpha-catenin is homologous to vinculin and the beta-catenin is homologous to human plakoglobin and the Drosophila gene product armadillo. With the use of peptide-specific anti plakoglobin antibodies were confirm here that plakoglobin is a component of the cadherin-catenin complex and that it is most likely identical to gamma-catenin. We show that plakoglobin binds directly to E-cadherin. We consolidate the biochemical evidence for the existence of two distinct and separable E-cadherin-catenin complexes in the same cell. One complex is composed of E-cadherin, alpha- and beta-catenin, the other of E-cadherin, alpha-catenin and plakoglobin. A similar distinct association with catenins is also found for other cadherins. Comparison of different cell lines revealed that the relative amounts of the two complexes vary depending on cell types.

    FEBS letters 1994;355;2;195-200

  • Plakoglobin and beta-catenin: distinct but closely related.

    Butz S, Stappert J, Weissig H and Kemler R

    Science (New York, N.Y.) 1992;257;5073;1142-4

  • The vertebrate adhesive junction proteins beta-catenin and plakoglobin and the Drosophila segment polarity gene armadillo form a multigene family with similar properties.

    Peifer M, McCrea PD, Green KJ, Wieschaus E and Gumbiner BM

    Department of Biology, University of North Carolina, Chapel Hill 27599.

    Three proteins identified by quite different criteria in three different systems, the Drosophila segment polarity gene armadillo, the human desmosomal protein plakoglobin, and the Xenopus E-cadherin-associated protein beta-catenin, share amino acid sequence similarity. These findings raise questions about the relationship among the three molecules and their roles in different cell-cell adhesive junctions. We have found that antibodies against the Drosophila segment polarity gene armadillo cross react with a conserved vertebrate protein. This protein is membrane associated, probably via its interaction with a cadherin-like molecule. This cross-reacting protein is the cadherin-associated protein beta-catenin. Using anti-armadillo and antiplakoglobin antibodies, it was shown that beta-catenin and plakoglobin are distinct molecules, which can coexist in the same cell type. Plakoglobin interacts with the desmosomal glycoprotein desmoglein I, and weakly with E-cadherin. Although beta-catenin interacts tightly with E-cadherin, it does not seem to be associated with either desmoglein I or with isolated desmosomes. Anti-armadillo antibodies have been further used to determine the intracellular localization of beta-catenin, and to examine its tissue distribution. The implications of these results for the structure and function of different cell-cell adhesive junctions are discussed.

    The Journal of cell biology 1992;118;3;681-91

  • Chromosomal assignment of the human genes coding for the major proteins of the desmosome junction, desmoglein DGI (DSG), desmocollins DGII/III (DSC), desmoplakins DPI/II (DSP), and plakoglobin DPIII (JUP).

    Arnemann J, Spurr NK, Wheeler GN, Parker AE and Buxton RS

    Laboratory of Eukaryotic Molecular Genetics, National Institute for Medical Research, London, United Kingdom.

    We have established PCR assays for the genes coding for the major proteins of the desmosome type of cell junction, the desmosomal cadherins DGI (desmoglein) and DGII/III (desmocollins), and the plaque proteins DPI/II (desmoplakin) and DPIII (plakoglobin) and used them to test human-mouse and human-rat somatic cell hybrids with different contents of human chromosomes. From these data we were able to assign DGI to chromosome 18 (DSG), DGII/III to chromosome 9p (DSC), DPI/II to chromosome 6p21-ter(DSP), and DPIII to chromosome 7 (JUP).

    Genomics 1991;10;3;640-5

  • Uvomorulin-catenin complex formation is regulated by a specific domain in the cytoplasmic region of the cell adhesion molecule.

    Ozawa M, Ringwald M and Kemler R

    Max-Planck-Institut für Immunbiologie, Forschergruppe Molekulare Embryologie, Stübeweg, Freiburg, Federal Republic of Germany.

    We have recently found that the cytoplasmic region of the cell adhesion molecule uvomorulin associates with three proteins named catenin alpha, beta, and gamma. Here we show by analysis of various mutant uvomorulin polypeptides expressed in mouse L cells that this association is mediated by a specific domain in the cytoplasmic region. A specific recognition site for catenins is located in a 72-amino acid domain. Interestingly, 69 of the 72 amino acid residues are encoded by a single exon of the uvomorulin gene. To demonstrate the direct interaction between catenins and the 72-amino acid domain, cDNA constructs composed of H-2Kd cDNA and various 3' sequences of uvomorulin were expressed in L cells. Chimeric proteins between H-2Kd and the 72-amino acid domain of uvomorulin were shown, by immunoprecipitation with anti-H-2Kd antibodies, to complex with catenin alpha, beta, and gamma. Catenins connect uvomorulin to cytoskeletal structures. We provide biochemical evidence for an association of the uvomorulin-catenin complex with actin bundles. Our results suggest that catenin alpha plays a key role in the association with actin filaments, whereas catenin beta binds more directly to the cytoplasmic region of uvomorulin. In cell aggregation assays with transfected cells expressing normal or mutant uvomorulin, the adhesive function was expressed only when uvomorulin was associated with catenins. From these results we conclude that the cytoplasmic anchorage of uvomorulin is of major biological importance.

    Proceedings of the National Academy of Sciences of the United States of America 1990;87;11;4246-50

  • The cytoplasmic domain of the cell adhesion molecule uvomorulin associates with three independent proteins structurally related in different species.

    Ozawa M, Baribault H and Kemler R

    Max-Planck-Institut für Immunbiologie, AG Molekulare Embryologie, Freiburg, FRG.

    Uvomorulin belongs to the group of Ca2+-dependent cell adhesion molecules, which are integral membrane proteins with several structural features in common. In particular, the cytoplasmic part of these proteins is highly conserved in different species, suggesting a common biological function. To test this assumption we transfected a uvomorulin full-length cDNA into uvomorulin-negative mouse NIH 3T3 and L cells. Immunoprecipitations with anti-uvomorulin antibodies detected, in addition to uvomorulin, three independent proteins of 102, 88 and 80 kd which are of host origin and which form complexes with uvomorulin. Using cDNA constructs coding for uvomorulin with cytoplasmic or extracellular deletions it is shown that the 102, 88 and 80 kd proteins complex with the cytoplasmic domain of uvomorulin. Peptide pattern analysis revealed that these three proteins are identical in different mouse cells. When uvomorulin cDNA was introduced into cell lines from other species, such as human HeLa and avian fibroblasts, the expressed uvomorulin was also associated with endogenous 102, 88 and 80 kd proteins and, moreover, each of these proteins showed structural similarities to the respective mouse molecule. A panel of antibodies specific for known cytoplasmic proteins of mol. wts similar to those of the three proteins did not react with any of the described components. This suggests that the 102, 88 and 80 kd proteins constitute a new group of proteins for which we propose the nomenclature of catenin alpha, beta and gamma respectively. The characterization of these proteins provides a first molecular basis for a possible cytoplasmic anchorage of uvomorulin to the cytoskeleton.

    The EMBO journal 1989;8;6;1711-7

  • Molecular cloning and amino acid sequence of human plakoglobin, the common junctional plaque protein.

    Franke WW, Goldschmidt MD, Zimbelmann R, Mueller HM, Schiller DL and Cowin P

    Division of Membrane Biology and Biochemistry, German Cancer Research Center, Heidelberg.

    Plakoglobin is a major cytoplasmic protein that occurs in a soluble and a membrane-associated form and is the only known constituent common to the submembranous plaques of both kinds of adhering junctions, the desmosomes and the intermediate junctions. Using a partial cDNA clone for bovine plakoglobin, we isolated cDNAs encoding human plakoglobin, determined its nucleotide sequence, and deduced the complete amino acid sequence. The polypeptide encoded by the cDNA was synthesized by in vitro transcription and translation and identified by its comigration with authentic plakoglobin in two-dimensional gel electrophoresis. The identity was further confirmed by comparison of the deduced sequence with the directly determined amino acid sequence of two fragments from bovine plakoglobin. Analysis of the plakoglobin sequence showed the protein (744 amino acids; 81,750 Da) to be unrelated to any other known proteins, highly conserved between human and bovine tissues, and characterized by numerous changes between hydrophilic and hydrophobic sections. Only one kind of plakoglobin mRNA (3.4 kilobases) was found in most tissues, but an additional mRNA (3.7 kilobases) was detected in certain human tumor cell lines. This longer mRNA may be represented by a second type of plakoglobin cDNA, which contains an insertion of 297 nucleotides in the 3' non-coding region.

    Proceedings of the National Academy of Sciences of the United States of America 1989;86;11;4027-31

  • Plakoglobin: a protein common to different kinds of intercellular adhering junctions.

    Cowin P, Kapprell HP, Franke WW, Tamkun J and Hynes RO

    We have established, by means of a monoclonal antibody and a cDNA clone, that a desmosomal polypeptide of Mr 83,000 also occurs at the plaques of other types of adhering junctions, including the vinculin-actin-associated intercellular junctions, e.g., the zonula adhaerens of epithelial cells and the endothelial, lens, and Sertoli cell junctions. This is the first component found in common among otherwise biochemically distinct plaque domains. Despite its concentration at these intercellular junctions, it is absent from the respective cell-substratum contact sites. In addition, it appears in a globular soluble 7S form in the cytoplasm. We discuss the significance of this protein, for which the name plakoglobin is proposed, in terms of its interaction with such biochemically diverse membrane domains and their different types of associated cytoskeletal filaments.

    Cell 1986;46;7;1063-73

Gene lists (5)

Gene List Source Species Name Description Gene count
L00000001 G2C Mus musculus Mouse PSD Mouse PSD adapted from Collins et al (2006) 1080
L00000008 G2C Mus musculus Mouse PSP Mouse PSP adapted from Collins et al (2006) 1121
L00000062 G2C Mus musculus BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus 984
L00000070 G2C Mus musculus BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list (ortho) 1461
L00000072 G2C Mus musculus BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list 1556
© G2C 2014. The Genes to Cognition Programme received funding from The Wellcome Trust and the EU FP7 Framework Programmes:
EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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