G2Cdb::Gene report

Gene id
Gene symbol
Homo sapiens
dynein, light chain, LC8-type 1
G00000759 (Mus musculus)

Databases (8)

Curated Gene
OTTHUMG00000135592 (Vega human gene)
ENSG00000088986 (Ensembl human gene)
8655 (Entrez Gene)
1179 (G2Cdb plasticity & disease)
DYNLL1 (GeneCards)
601562 (OMIM)
Marker Symbol
HGNC:15476 (HGNC)
Protein Sequence
P63167 (UniProt)

Synonyms (5)

  • DLC1
  • DLC8
  • LC8
  • PIN
  • hdlc1

Literature (60)

Pubmed - other

  • Defining the human deubiquitinating enzyme interaction landscape.

    Sowa ME, Bennett EJ, Gygi SP and Harper JW

    Department of Pathology, Harvard Medical School, Boston, MA 02115, USA.

    Deubiquitinating enzymes (Dubs) function to remove covalently attached ubiquitin from proteins, thereby controlling substrate activity and/or abundance. For most Dubs, their functions, targets, and regulation are poorly understood. To systematically investigate Dub function, we initiated a global proteomic analysis of Dubs and their associated protein complexes. This was accomplished through the development of a software platform called CompPASS, which uses unbiased metrics to assign confidence measurements to interactions from parallel nonreciprocal proteomic data sets. We identified 774 candidate interacting proteins associated with 75 Dubs. Using Gene Ontology, interactome topology classification, subcellular localization, and functional studies, we link Dubs to diverse processes, including protein turnover, transcription, RNA processing, DNA damage, and endoplasmic reticulum-associated degradation. This work provides the first glimpse into the Dub interaction landscape, places previously unstudied Dubs within putative biological pathways, and identifies previously unknown interactions and protein complexes involved in this increasingly important arm of the ubiquitin-proteasome pathway.

    Funded by: NIA NIH HHS: AG085011, R01 AG011085, R01 AG011085-16; NIGMS NIH HHS: GM054137, GM67945, R01 GM054137, R01 GM054137-14, R01 GM067945

    Cell 2009;138;2;389-403

  • Interaction with LC8 is required for Pak1 nuclear import and is indispensable for zebrafish development.

    Lightcap CM, Kari G, Arias-Romero LE, Chernoff J, Rodeck U and Williams JC

    Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA.

    Pak1 (p21 activated kinase 1) is a serine/threonine kinase implicated in regulation of cell motility and survival and in malignant transformation of mammary epithelial cells. In addition, the dynein light chain, LC8, has been described to cooperate with Pak1 in malignant transformation of breast cancer cells. Pak1 itself may aid breast cancer development by phosphorylating nuclear proteins, including estrogen receptor alpha. Recently, we showed that the LC8 binding site on Pak1 is adjacent to the nuclear localization sequence (NLS) required for Pak1 nuclear import. Here, we demonstrate that the LC8-Pak1 interaction is necessary for epidermal growth factor (EGF)-induced nuclear import of Pak1 in MCF-7 cells, and that this event is contingent upon LC8-mediated Pak1 dimerization. In contrast, Pak2, which lacks an LC8 binding site but contains a nuclear localization sequence identical to that in Pak1, remains cytoplasmic upon EGF stimulation of MCF-7 cells. Furthermore, we show that severe developmental defects in zebrafish embryos caused by morpholino injections targeting Pak are partially rescued by co-injection of wild-type human Pak1, but not by co-injection of mutant Pak1 mRNA disrupting either the LC8 binding or the NLS site. Collectively, these results suggest that LC8 facilitates nuclear import of Pak1 and that this function is indispensable during vertebrate development.

    Funded by: NCI NIH HHS: R01 CA081008, R01 CA117884, R01 CA81008; NCRR NIH HHS: S10 RR022316, S10-RR022316

    PloS one 2009;4;6;e6025

  • Residue-wise conformational stability of DLC8 dimer from native-state hydrogen exchange.

    Mohan PM, Chakraborty S and Hosur RV

    Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India.

    Dynein light chain (DLC8) is the smallest subunit of the dynein motor complex, which is known to act as a cargo adaptor in intracellular trafficking. The protein exists as a pure dimer at physiological pH and a completely folded monomer below pH 4. Here, we have determined the energy landscape of the dimeric protein using a combination of optical techniques and native-state hydrogen exchange of amide groups, the former giving the global features and the latter yielding the residue level details. The data indicated the presence of intermediates along the equilibrium unfolding transition. The hydrogen exchange data suggested that the molecule has differential stability in its various segments. We deduce from the free energy data that the antiparallel beta-sheets (beta4 and beta5) that form the hydrophobic core of the protein and the alpha2 helix, all of which are highly protected with regard to hydrogen exchange, contribute significantly to the initial step of the protein folding mechanism. Denaturant-dependent hydrogen exchange indicated further that some amides exchange via local fluctuations, whereas there are others which exchange via global unfolding events. Implications of these to cargo adaptability of the dimer are discussed.

    Proteins 2009;75;1;40-52

  • Hierarchy in guanidine unfolding of DLC8 dimer: regulatory functional implications.

    Mohan PM, Joshi MV and Hosur RV

    Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, Maharashtra, India.

    Folding-unfolding caused by environmental changes play crucial regulatory roles in protein functions. To gain an insight into these for DLC8, a cargo adaptor in dynein motor complex, we investigated here the unfolding of homodimeric DLC8 by GdnHCl, a standard unfolding agent. Fluorescence spectroscopy revealed a three-state unfolding transition with midpoints at 1.5 and 4.0 M GdnHCl. The HSQC spectrum at 1.5 M GdnHCl displayed peaks belonging to a folded monomer. NMR chemical shift perturbations, line broadening effects and (15)N relaxation measurements at low GdnHCl concentrations identified a hierarchy in the unfolding process, with the dimer interface--the cargo binding site--being the most susceptible followed by the helices in the interior. Similar observations were made earlier for small pH perturbations and thus the early unfolding events appear to be intrinsic to the protein. These, by virtue of their location, influence target binding efficacies and thus have important regulatory implications.

    Biochimie 2009;91;3;401-7

  • A PP2A phosphatase high density interaction network identifies a novel striatin-interacting phosphatase and kinase complex linked to the cerebral cavernous malformation 3 (CCM3) protein.

    Goudreault M, D'Ambrosio LM, Kean MJ, Mullin MJ, Larsen BG, Sanchez A, Chaudhry S, Chen GI, Sicheri F, Nesvizhskii AI, Aebersold R, Raught B and Gingras AC

    Samuel Lunenfeld Research Institute at Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.

    The serine/threonine protein phosphatases are targeted to specific subcellular locations and substrates in part via interactions with a wide variety of regulatory proteins. Understanding these interactions is thus critical to understanding phosphatase function. Using an iterative affinity purification/mass spectrometry approach, we generated a high density interaction map surrounding the protein phosphatase 2A catalytic subunit. This approach recapitulated the assembly of the PP2A catalytic subunit into many different trimeric complexes but also revealed several new protein-protein interactions. Here we define a novel large multiprotein assembly, referred to as the striatin-interacting phosphatase and kinase (STRIPAK) complex. STRIPAK contains the PP2A catalytic (PP2Ac) and scaffolding (PP2A A) subunits, the striatins (PP2A regulatory B''' subunits), the striatin-associated protein Mob3, the novel proteins STRIP1 and STRIP2 (formerly FAM40A and FAM40B), the cerebral cavernous malformation 3 (CCM3) protein, and members of the germinal center kinase III family of Ste20 kinases. Although the function of the CCM3 protein is unknown, the CCM3 gene is mutated in familial cerebral cavernous malformations, a condition associated with seizures and strokes. Our proteomics survey indicates that a large portion of the CCM3 protein resides within the STRIPAK complex, opening the way for further studies of CCM3 biology. The STRIPAK assembly establishes mutually exclusive interactions with either the CTTNBP2 proteins (which interact with the cytoskeletal protein cortactin) or a second subcomplex consisting of the sarcolemmal membrane-associated protein (SLMAP) and the related coiled-coil proteins suppressor of IKKepsilon (SIKE) and FGFR1OP2. We have thus identified several novel PP2A-containing protein complexes, including a large assembly linking kinases and phosphatases to a gene mutated in human disease.

    Funded by: NHLBI NIH HHS: N01-HV-28179, N01HV28179

    Molecular & cellular proteomics : MCP 2009;8;1;157-71

  • pH dependent unfolding characteristics of DLC8 dimer: Residue level details from NMR.

    Mohan PM and Hosur RV

    Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, India.

    Environment dependence of folding and unfolding of a protein is central to its function. In the same vein, knowledge of pH dependence of stability and folding/unfolding is crucial for many biophysical equilibrium and kinetic studies designed to understand protein folding mechanisms. In the present study we investigated the guanidine induced unfolding transition of dynein light chain protein (DLC8), a cargo adaptor of the dynein complex in the pH range 7-10. It is observed that while the protein remains a dimer in the entire pH range, its stability is somewhat reduced at alkaline pH. Global unfolding features monitored using fluorescence spectroscopy revealed that the unfolding transition of DLC8 at pH 7 is best described by a three-state model, whereas, that at pH 10 is best described by a two-state model. Chemical shift perturbations due to pH change provided insights into the corresponding residue level structural perturbations in the DLC8 dimer. Likewise, backbone (15)N relaxation measurements threw light on the corresponding motional changes in the dimeric protein. These observations have been rationalized on the basis of expected changes with increasing pH in the protonation states of the titratable residues on the structure of the protein. These, in turn provide an explanation for the change from three-state to two-state guanidine induced unfolding transition as the pH is increased from 7 to 10. All these results exemplify and highlight the role of environment vis-à-vis the sequence and structure of a given protein in dictating its folding/unfolding characteristics.

    Biochimica et biophysica acta 2008;1784;11;1795-803

  • Dynein light chain LC8 negatively regulates NF-kappaB through the redox-dependent interaction with IkappaBalpha.

    Jung Y, Kim H, Min SH, Rhee SG and Jeong W

    Department of Life Science, Division of Life and Pharmaceutical Sciences, and Center for Cell Signaling and Drug Discovery Research, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-gu, Seoul, Korea.

    Redox regulation of nuclear factor kappaB (NF-kappaB) has been described, but the molecular mechanism underlying such regulation has remained unclear. We recently showed that a novel disulfide reductase, TRP14, inhibits tumor necrosis factor alpha (TNFalpha)-induced NF-kappaB activation, and we identified the dynein light chain LC8, which interacts with the NF-kappaB inhibitor IkappaBalpha, as a potential substrate of TRP14. We now show the molecular mechanism by which NF-kappaB activation is redox-dependently regulated through LC8. LC8 inhibited TNFalpha-induced NF-kappaB activation in HeLa cells by interacting with IkappaBalpha and thereby preventing its phosphorylation by IkappaB kinase (IKK), without affecting the activity of IKK itself. TNFalpha induced the production of reactive oxygen species, which oxidized LC8 to a homodimer linked by the reversible formation of a disulfide bond between the Cys(2) residues of each subunit and thereby resulted in its dissociation from IkappaBalpha. Butylated hydroxyanisol, an antioxidant, and diphenyleneiodonium, an inhibitor of NADPH oxidase, attenuated the phosphorylation and degradation of IkappaBalpha by TNFalpha stimulation. In addition LC8 inhibited NF-kappaB activation by other stimuli including interleukin-1beta and lipopolysaccharide, both of which generated reactive oxygen species. Furthermore, TRP14 catalyzed reduction of oxidized LC8. Together, our results indicate that LC8 binds IkappaBalpha in a redox-dependent manner and thereby prevents its phosphorylation by IKK. TRP14 contributes to this inhibitory activity by maintaining LC8 in a reduced state.

    The Journal of biological chemistry 2008;283;35;23863-71

  • RACK1 and CIS mediate the degradation of BimEL in cancer cells.

    Zhang W, Cheng GZ, Gong J, Hermanto U, Zong CS, Chan J, Cheng JQ and Wang LH

    Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029, USA.

    RACK1 is a 7-WD motif-containing protein with numerous downstream effectors regulating various cellular functions. Using a yeast two-hybrid screen, we identified dynein light chain 1 as a novel interacting partner of RACK1. Additionally, we demonstrated that RACK1 formed a complex with DLC1 and Bim, specifically BimEL, in the presence of apoptotic agents. Upon paclitaxel treatment, RACK1, DLC1, and CIS mediated the degradation of BimEL through the ElonginB/C-Cullin2-CIS ubiquitin-protein isopeptide ligase complex. We further showed that RACK1 conferred paclitaxel resistance to breast cancer cells in vitro and in vivo. Finally, we observed an inverse correlation between CIS and BimEL levels in both ovarian and breast cancer cell lines and specimens. Our study suggests a role of RACK1 in protecting cancer cells from apoptosis by regulating the degradation of BimEL, which together with CIS could play an important role of drug resistance in chemotherapy.

    Funded by: NCI NIH HHS: CA29339

    The Journal of biological chemistry 2008;283;24;16416-26

  • Serine 88 phosphorylation of the 8-kDa dynein light chain 1 is a molecular switch for its dimerization status and functions.

    Song C, Wen W, Rayala SK, Chen M, Ma J, Zhang M and Kumar R

    Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.

    Dynein light chain 1 (DLC1, also known as DYNLL1, LC8, and PIN), a ubiquitously expressed and highly conserved protein, participates in a variety of essential intracellular events. Transition of DLC1 between dimer and monomer forms might play a crucial role in its function. However, the molecular mechanism(s) that control the transition remain unknown. DLC1 phosphorylation on Ser(88) by p21-activated kinase 1 (Pak1), a signaling nodule, promotes mammalian cell survival by regulating its interaction with Bim and the stability of Bim. Here we discovered that phosphorylation of Ser(88), which juxtapose each other at the interface of the DLC dimer, disrupts DLC1 dimer formation and consequently impairs its interaction with Bim. Overexpression of a Ser(88) phosphorylation-inactive DLC1 mutant in mammary epithelium cells and in a transgenic animal model caused apoptosis and accelerated mammary gland involution, respectively, with increased Bim levels. Structural and biophysical studies suggested that phosphorylation-mimicking mutation leads to dissociation of the DLC1 dimer to a pure folded monomer. The phosphorylation-induced DLC1 monomer is incapable of binding to its substrate Bim. These findings reveal a previously unrecognized regulatory mechanism of DLC1 in which the Ser(88) phosphorylation acts as a molecular switch for the transition of DLC1 from dimer to monomer, thereby modulating its interaction with substrates and consequently regulating the functions of DLC1.

    Funded by: NCI NIH HHS: CA80066, CA90970

    The Journal of biological chemistry 2008;283;7;4004-13

  • Regulation and function of the protein inhibitor of nitric oxide synthase (PIN)/dynein light chain 8 (LC8) in a human mast cell line.

    McCauley SD, Gilchrist M and Befus AD

    Glaxo-Heritage Asthma Research Laboratory, Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada.

    The protein inhibitor of nitric oxide synthase (PIN) was independently identified as an inhibitor of nitric oxide (NO) produced by neuronal nitric oxide synthase (nNOS), and as a member of the cellular dynein light chain family, dynein light chain 8 (LC8), responsible for intracellular protein trafficking. Mast cells (MC) are involved in several homeostatic and pathological processes and can be regulated by NO. This study describes the expression of PIN/LC8 in the human MC line HMC-1. We also studied if PIN/LC8 binds nNOS, and what role this might have in leukotriene (LT) production. We found that PIN/LC8 mRNA and protein was expressed in HMC-1. Using a GST-PIN construct, we showed PIN binds to nNOS, but not endothelial (e)NOS in HMC-1; in our studies HMC-1 did not express inducible (i)NOS. Intracellular delivery of anti-PIN/LC8 antibody enhanced ionophore (A23187)-induced LT production through an unknown mechanism. Thus we established for the first time expression of PIN/LC8 in human MC, its ability to bind nNOS, and the effect that blocking it has on LT production in a human MC lines.

    Life sciences 2007;80;10;959-64

  • Large-scale mapping of human protein-protein interactions by mass spectrometry.

    Ewing RM, Chu P, Elisma F, Li H, Taylor P, Climie S, McBroom-Cerajewski L, Robinson MD, O'Connor L, Li M, Taylor R, Dharsee M, Ho Y, Heilbut A, Moore L, Zhang S, Ornatsky O, Bukhman YV, Ethier M, Sheng Y, Vasilescu J, Abu-Farha M, Lambert JP, Duewel HS, Stewart II, Kuehl B, Hogue K, Colwill K, Gladwish K, Muskat B, Kinach R, Adams SL, Moran MF, Morin GB, Topaloglou T and Figeys D

    Protana, Toronto, Ontario, Canada.

    Mapping protein-protein interactions is an invaluable tool for understanding protein function. Here, we report the first large-scale study of protein-protein interactions in human cells using a mass spectrometry-based approach. The study maps protein interactions for 338 bait proteins that were selected based on known or suspected disease and functional associations. Large-scale immunoprecipitation of Flag-tagged versions of these proteins followed by LC-ESI-MS/MS analysis resulted in the identification of 24,540 potential protein interactions. False positives and redundant hits were filtered out using empirical criteria and a calculated interaction confidence score, producing a data set of 6463 interactions between 2235 distinct proteins. This data set was further cross-validated using previously published and predicted human protein interactions. In-depth mining of the data set shows that it represents a valuable source of novel protein-protein interactions with relevance to human diseases. In addition, via our preliminary analysis, we report many novel protein interactions and pathway associations.

    Molecular systems biology 2007;3;89

  • The exchange factor and diacylglycerol receptor RasGRP3 interacts with dynein light chain 1 through its C-terminal domain.

    Okamura SM, Oki-Idouchi CE and Lorenzo PS

    Natural Products and Cancer Biology Program, Cancer Research Center of Hawaii, University of Hawaii, Honolulu, Hawaii 96813, USA.

    RasGRP3 is an exchange factor for Ras-like small GTPases that is activated in response to the second messenger diacylglycerol. As with other diacylglycerol receptors, RasGRP3 is redistributed upon diacylglycerol or phorbol ester binding. Several factors are important in determining the pattern of translocation, including the potency of the diacylglycerol analog, the affinity of the receptor for phospholipids, and in some cases, protein-protein interactions. However, little is known about the mechanisms that play a role in RasGRP3 redistribution aside from the nature of the ligand. To discover potential protein binding partners for RasGRP3, we screened a human brain cDNA library using a yeast two-hybrid approach. We identified dynein light chain 1 as a novel RasGRP3-interacting protein. The interaction was confirmed both in vitro and in vivo and required the C-terminal domain encompassing the last 127 amino acids of RasGRP3. A truncated mutant form of RasGRP3 that lacked this C-terminal domain was unable to interact with dynein light chain 1 and displayed a dramatically altered subcellular localization, with a strong reticular distribution and perinuclear and nuclear localization. These findings suggest that dynein light chain 1 represents a novel anchoring protein for RasGRP3 that may regulate subcellular localization of the exchange factor and, as such, may participate in the signaling mediated by diacylglycerol through RasGRP3.

    Funded by: NCRR NIH HHS: RCMI-G12RR003061

    The Journal of biological chemistry 2006;281;47;36132-9

  • Dazl can bind to dynein motor complex and may play a role in transport of specific mRNAs.

    Lee KH, Lee S, Kim B, Chang S, Kim SW, Paick JS and Rhee K

    Department of Biological Sciences and Research Center for Functional Cellulomics, Seoul National University, Seoul, Korea.

    Male germ cell development includes mitotic and meiotic cell divisions that are followed by dramatic morphological changes resulting in the production of spermatozoa. Genetic evidence has indicated that the DAZ family genes are critical for successful male germ cell development in diverse animals as well as humans. In the present study, we investigated the cellular functions of Dazl in the mouse male germ cells. We identified a specific interaction of Dazl with the dynein light chain, a component of the dynein-dynactin motor complex. The subcellular distribution of Dazl was microtubule-dependent and a selected number of Dazl-bound mRNAs could accumulate in the perinuclear area. Based on these results, we propose that Dazl may play a role in transport of specific mRNAs via dynein motor complex. The Dazl-bound mRNAs may be stored at specific sites and would be available for future developmental processes. Our study revealed the presence of an active mRNA transport system in mouse male germ cells.

    The EMBO journal 2006;25;18;4263-70

  • PIN inhibits nitric oxide and superoxide production from purified neuronal nitric oxide synthase.

    Xia Y, Berlowitz CO and Zweier JL

    Davis Heart and Lung Research Institute, Department of Cardiovascular Medicine, Department of Molecular and Cellular Biochemistry, The Ohio State University, 473 West 12th Avenue, Columbus, OH 43210, USA. yong.xia@osumc.edu

    A protein inhibitor of neuronal nitric oxide synthase (nNOS) was identified and designated as PIN. PIN was reported to inhibit nNOS activity in cell lysates through disruption of enzyme dimerization. However, there has been lack of direct characterization of the effect of PIN on NO production from purified nNOS. Furthermore, nNOS also generates superoxide (.O(2)(-)) at low levels of L-arginine. It is unknown whether PIN affects .O(2)(-) generation from nNOS. Therefore, we performed direct measurements of the effects of PIN on NO and .O(2)(-) generation from purified nNOS using electron paramagnetic resonance spin trapping techniques. nNOS was isolated by affinity chromatography and a fusion protein CBP-PIN was used to probe the effect of PIN. While the tag CBP did not affect nNOS activity, CBP-PIN caused a dose-dependent inhibition on both NO and L-citrulline production. In the absence of L-arginine, strong .O(2)(-) generation was observed from nNOS, and this was blocked by CBP-PIN in a dose-dependent manner. With low-temperature polyacrylamide gel electrophoresis, neither CBP nor CBP-PIN was found to affect nNOS dimerization. Thus, these results suggested that PIN not only inhibits NO but also .O(2)(-) production from nNOS, and this is through a mechanism other than decomposition of nNOS dimers.

    Funded by: NHLBI NIH HHS: HL 38324, HL 77575; NIA NIH HHS: AG 00835

    Biochimica et biophysica acta 2006;1760;9;1445-9

  • Essential role of KIBRA in co-activator function of dynein light chain 1 in mammalian cells.

    Rayala SK, den Hollander P, Manavathi B, Talukder AH, Song C, Peng S, Barnekow A, Kremerskothen J and Kumar R

    Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.

    Recently dynein light chain 1 (DLC1), a cytoskeleton signaling component, has been shown to interact with and transactivate estrogen receptor-alpha (ER), leading to increased expression of ER target genes and growth stimulation of breast cancer cells. However, the molecular mechanism by which DLC1 regulates the ER pathway remains poorly understood. To gain insights into the putative mechanism, here we set out to identify novel DLC1-interacting proteins. We identified KIBRA, a WW domain- and a glutamic acid stretch-containing protein, as a DLC1-binding protein and showed that it interacts with DLC1 both in vitro and in vivo. We found that KIBRA-DLC1 complex is recruited to ER-responsive promoters. We also found that KIBRA-DLC1 interaction is mandatory for the recruitment and transactivation functions of ER or DLC1 to the target chromatin. Finally we found that KIBRA interacts with histone H3 via its glutamic acid-rich region and that such interaction might play a mechanistic role in conferring an optimal ER transactivation function as well as the proliferation of ligand-stimulated breast cancer cells. Together these findings indicate that DLC1-KIBRA interaction is essential for ER transactivation in breast cancer cells.

    Funded by: NCI NIH HHS: CA65746, CA80066

    The Journal of biological chemistry 2006;281;28;19092-9

  • The PITSLRE/CDK11p58 protein kinase promotes centrosome maturation and bipolar spindle formation.

    Petretti C, Savoian M, Montembault E, Glover DM, Prigent C and Giet R

    CNRS UMR 6061 Université de Rennes I, Equipe Labellisée Ligue Nationale Contre le Cancer, IFR140 GFAS, Faculté de Médecine, France.

    The CDK11 (cyclin-dependent kinase 11) gene has an internal ribosome entry site (IRES), allowing the expression of two protein kinases. The longer 110-kDa isoform is expressed at constant levels during the cell cycle and the shorter 58-kDa isoform is expressed only during G2 and M phases. By means of RNA interference (RNAi), we show that the CDK11 gene is required for mitotic spindle formation. CDK11 RNAi leads to mitotic checkpoint activation. Mitotic cells are arrested with short or monopolar spindles. gamma-Tubulin as well as Plk1 and Aurora A protein kinase levels are greatly reduced at centrosomes, resulting in microtubule nucleation defects. We show that the mitotic CDK11(p58) isoform, but not the CDK11(p110) isoform, associates with mitotic centrosomes and rescues the phenotypes resulting from CDK11 RNAi. This work demonstrates for the first time the role of CDK11(p58) in centrosome maturation and bipolar spindle morphogenesis.

    EMBO reports 2006;7;4;418-24

  • Transcriptome analysis of human gastric cancer.

    Oh JH, Yang JO, Hahn Y, Kim MR, Byun SS, Jeon YJ, Kim JM, Song KS, Noh SM, Kim S, Yoo HS, Kim YS and Kim NS

    Laboratory of Human Genomics, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon , 305-333, Korea.

    To elucidate the genetic events associated with gastric cancer, 124,704 cDNA clones were collected from 37 human gastric cDNA libraries, including 20 full-length enriched cDNA libraries of gastric cancer cell lines and tissues from Korean patients. An analysis of the collected ESTs revealed that 97,930 high-quality ESTs coalesced into 13,001 clusters, of which 11,135 clusters (85.6%) were annotated to known ESTs. The analysis of the full-length cDNAs also revealed that 4862 clusters (51.7%) contained at least one putative full-length cDNA clone with an initiation codon, with the average length of the 5' UTR of 140 bp. A large number appear to have a diverse transcription start site (TSS). An examination of the TSS of some genes, such as TEGT and GAPD, using 5' RACE revealed that the predicted TSSs are actually found in human gastric cancer cells and that several TSSs differ depending on the specific gastric cell line. Furthermore, of the human gastric ESTs, 766 genes (9.5%) were present as putative alternatively spliced variants. Confirmation of the predicted spliced isoforms using RT-PCR showed that the predicted isoforms exist in gastric cancer cells and some isoforms coexist in gastric cell lines. These results provide potentially useful information for elucidating the molecular mechanisms associated with gastric oncogenesis.

    Mammalian genome : official journal of the International Mammalian Genome Society 2005;16;12;942-54

  • Cytoplasmic dynein nomenclature.

    Pfister KK, Fisher EM, Gibbons IR, Hays TS, Holzbaur EL, McIntosh JR, Porter ME, Schroer TA, Vaughan KT, Witman GB, King SM and Vallee RB

    Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA. kkp9w@virginia.edu

    A variety of names has been used in the literature for the subunits of cytoplasmic dynein complexes. Thus, there is a strong need for a more definitive consensus statement on nomenclature. This is especially important for mammalian cytoplasmic dyneins, many subunits of which are encoded by multiple genes. We propose names for the mammalian cytoplasmic dynein subunit genes and proteins that reflect the phylogenetic relationships of the genes and the published studies clarifying the functions of the polypeptides. This nomenclature recognizes the two distinct cytoplasmic dynein complexes and has the flexibility to accommodate the discovery of new subunits and isoforms.

    Funded by: NIGMS NIH HHS: R01 GM030626, R01 GM060560, R01 GM060560-05

    The Journal of cell biology 2005;171;3;411-3

  • A human protein-protein interaction network: a resource for annotating the proteome.

    Stelzl U, Worm U, Lalowski M, Haenig C, Brembeck FH, Goehler H, Stroedicke M, Zenkner M, Schoenherr A, Koeppen S, Timm J, Mintzlaff S, Abraham C, Bock N, Kietzmann S, Goedde A, Toksöz E, Droege A, Krobitsch S, Korn B, Birchmeier W, Lehrach H and Wanker EE

    Max Delbrueck Center for Molecular Medicine, 13092 Berlin-Buch, Germany.

    Protein-protein interaction maps provide a valuable framework for a better understanding of the functional organization of the proteome. To detect interacting pairs of human proteins systematically, a protein matrix of 4456 baits and 5632 preys was screened by automated yeast two-hybrid (Y2H) interaction mating. We identified 3186 mostly novel interactions among 1705 proteins, resulting in a large, highly connected network. Independent pull-down and co-immunoprecipitation assays validated the overall quality of the Y2H interactions. Using topological and GO criteria, a scoring system was developed to define 911 high-confidence interactions among 401 proteins. Furthermore, the network was searched for interactions linking uncharacterized gene products and human disease proteins to regulatory cellular pathways. Two novel Axin-1 interactions were validated experimentally, characterizing ANP32A and CRMP1 as modulators of Wnt signaling. Systematic human protein interaction screens can lead to a more comprehensive understanding of protein function and cellular processes.

    Cell 2005;122;6;957-68

  • A screen for proteins that interact with PAX6: C-terminal mutations disrupt interaction with HOMER3, DNCL1 and TRIM11.

    Cooper ST and Hanson IM

    University of Edinburgh, School of Molecular and Clinical Medicine, Medical Sciences (Medical Genetics), Molecular Medicine Centre, Western General Hospital, Edinburgh EH4 2XU. simon.t.cooper@ed.ac.uk

    Background: The PAX6 protein is a transcriptional regulator with a key role in ocular and neurological development. Individuals with heterozygous loss-of-function mutations in the PAX6 gene have malformations of the eye and brain. Little is known about the interactions of PAX6 with other proteins, so we carried out a systematic screen for proteins that interact with PAX6.

    Results: We used bioinformatics techniques to characterise a highly conserved peptide at the C-terminus of the PAX6 protein. Yeast two-hybrid library screens were then carried out to identify brain-expressed proteins that interact with the C-terminal peptide and with the entire PAX6 proline-serine-threonine-rich domain. Three novel PAX6-interacting proteins were identified: the post-synaptic density (PSD) protein HOMER3, the dynein subunit DNCL1, and the tripartite motif protein TRIM11. Three C-terminal PAX6 mutations, previously identified in patients with eye malformations, all reduced or abolished the interactions.

    Conclusion: Our preliminary data suggest that PAX6 interacts with HOMER3, DNCL1 and TRIM11. We propose that the interaction of PAX6 with HOMER3 and DNCL1 is a mechanism by which synaptic activation could lead to changes in neuronal transcriptional activity, and that some of the neural anomalies in patients with PAX6 mutations could be explained by impaired protein-protein interactions.

    BMC genetics 2005;6;43

  • Functional regulation of oestrogen receptor pathway by the dynein light chain 1.

    Rayala SK, den Hollander P, Balasenthil S, Yang Z, Broaddus RR and Kumar R

    Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030, USA.

    Overexpression and phosphorylation of dynein light chain 1 (DLC1) have been shown to promote the growth of breast cancer cells. However, the role of DLC1 in the action of the oestrogen receptor (ER) remains unknown. Here, we found that oestrogen induces the transcription and expression of DLC1. DLC1 facilitated oestrogen-induced ER transactivation and anchorage-independent growth of breast cancer cells. We show that DLC1 interacts with ER, and such interaction is required for the transactivation-promoting activity of DLC1. Further, DLC1 expression led to enhanced recruitment of the DLC1-ER complex to the ER-target gene chromatin. Conversely, DLC1 downregulation compromised the ER-transactivation activity and also its nuclear accumulation, suggesting a potential chaperone-like activity of DLC1 in the nuclear translocation of ER. Together, these data define an unexpected upregulation of DLC1 by oestrogen and a previously unrecognized DLC1-ER interaction in supporting and amplifying ER-initiated cellular responses in breast cancer cells.

    EMBO reports 2005;6;6;538-44

  • The 8-kDa dynein light chain binds to p53-binding protein 1 and mediates DNA damage-induced p53 nuclear accumulation.

    Lo KW, Kan HM, Chan LN, Xu WG, Wang KP, Wu Z, Sheng M and Zhang M

    Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.

    The tumor suppressor protein p53 is known to undergo cytoplasmic dynein-dependent nuclear translocation in response to DNA damage. However, the molecular link between p53 and the minus end-directed microtubule motor dynein complex has not been described. We report here that the 8-kDa light chain (LC8) of dynein binds to p53-binding protein 1 (53BP1). The LC8-binding domain was mapped to a short peptide segment immediately N-terminal to the kinetochore localization region of 53BP1. The LC8-binding domain is completely separated from the p53-binding domain in 53BP1. Therefore, 53BP1 can potentially act as an adaptor to assemble p53 to the dynein complex. Unlike other known LC8-binding proteins, 53BP1 contains two distinct LC8-binding motifs that are arranged in tandem. We further showed that 53BP1 can directly associate with the dynein complex. Disruption of the interaction between LC8 and 53BP1 in vivo prevented DNA damage-induced nuclear accumulation of p53. These data illustrate that LC8 is able to function as a versatile acceptor to link a wide spectrum of molecular cargoes to the dynein motor.

    The Journal of biological chemistry 2005;280;9;8172-9

  • Alterations in mitochondrial and apoptosis-regulating gene expression in photodynamic therapy-resistant variants of HT29 colon carcinoma cells.

    Shen XY, Zacal N, Singh G and Rainbow AJ

    Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada.

    Photodynamic therapy (PDT) is a novel cancer therapy inducing irreversible photodamage to tumor tissue via photosensitizer-mediated oxidative cytotoxicity. The cellular and molecular responses associated with PDT are only partially understood. We have reported previously the generation of several photosensitizer-specific PDT-resistant cell variants of HT29 human colon adenocarcinoma cells by selecting cells from sequential PDT treatment using different photosensitizers. In this report, we describe the use of messenger RNA (mRNA) differential display to identify genes that were differentially expressed in the parental HT29 cells compared with their resistant variants. In comparison with parental HT29 cells, mRNA expression was increased in the PDT-resistant cell variants for BNIP3, estrogen receptor-binding fragment-associated gene 9, Myh-1c, cytoplasmic dynein light chain 1, small membrane protein I and differential dependent protein. In contrast, expression in the PDT-resistant variants was downregulated for NNX3, human HepG2 3' region Mbol complementary DNA, glutamate dehydrogenase, hepatoma-derived growth factor and the mitochondrial genes coding for 16S ribosomal RNA (rRNA) and nicotinamide adenine dinucleotide (NADH) dehydrogenase subunit 4. The reduction for mitochondrial 16S rRNA in the PDT-resistant variants was confirmed by Northern blotting, and the elevated expression of the proapoptotic BNIP3 in the PDT-resistant variants was confirmed by Northern and Western blotting analysis. We also examined the expression of some additional apoptosis-regulating genes using Western blotting. We show an increased expression of Bcl-2 and heat shock protein 27 and a downregulation of Bax in the PDT-resistant variants. In addition, the mutant p53 levels in the parental HT29 cells were reduced substantially in the PDT-resistant variants. We suggest that the altered expression in several mitochondrial and apoptosis-regulating genes contributes to PDT resistance.

    Photochemistry and photobiology 2005;81;2;306-13

  • Dynein light chain 1 phosphorylation controls macropinocytosis.

    Yang Z, Vadlamudi RK and Kumar R

    Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.

    Recent studies have identified dynein light chain-1 (DLC1), a component of the dynein motor, as a p21-activated kinase 1 (Pak1)-interacting substrate with binding sites mapped to amino acids 61-89 of DLC1 and phosphorylation site at serine 88. Here we investigated the role of DLC1 phosphorylation by Pak1 upon the process of macropinocytosis. We found that Pak1 associates with dynein motor and that Pak1-DLC1 interaction starts at the initiation of pinosome formation and persists in early and late endosomes. Pak1 phosphorylation of DLC1 on Ser-88 controls vesicle formation and trafficking functions, as Ser-88 substitution for alanine prevents macropinocytosis. A peptide spanning the C-terminal 19-amino acid region of DLC1 efficiently blocked Ser-88 phosphorylation and macropinocytosis. These results suggest that the regulation of DLC1 by Pak1 is a novel mechanism by which a signaling kinase might influence macropinocytosis.

    Funded by: NCI NIH HHS: CA80066, CA90970

    The Journal of biological chemistry 2005;280;1;654-9

  • Herpes simplex virus type 1 capsid protein VP26 interacts with dynein light chains RP3 and Tctex1 and plays a role in retrograde cellular transport.

    Douglas MW, Diefenbach RJ, Homa FL, Miranda-Saksena M, Rixon FJ, Vittone V, Byth K and Cunningham AL

    Centre for Virus Research, Westmead Millennium Institute, University of Sydney and Westmead Hospital, Westmead 2145, New South Wales, Australia.

    Cytoplasmic dynein is the major molecular motor involved in minus-end-directed cellular transport along microtubules. There is increasing evidence that the retrograde transport of herpes simplex virus type 1 along sensory axons is mediated by cytoplasmic dynein, but the viral and cellular proteins involved are not known. Here we report that the herpes simplex virus outer capsid protein VP26 interacts with dynein light chains RP3 and Tctex1 and is sufficient to mediate retrograde transport of viral capsids in a cellular model. A library of herpes simplex virus capsid and tegument structural genes was constructed and tested for interactions with dynein subunits in a yeast two-hybrid system. A strong interaction was detected between VP26 and the homologous 14-kDa dynein light chains RP3 and Tctex1. In vitro pull-down assays confirmed binding of VP26 to RP3, Tctex1, and intact cytoplasmic dynein complexes. Recombinant herpes simplex virus capsids were constructed either with or without VP26. In pull-down assays VP26+ capsids bound to RP3; VP26-capsids did not. To investigate intracellular transport, the recombinant viral capsids were microinjected into living cells and incubated at 37 degrees C. After 1 h VP26+ capsids were observed to co-localize with RP3, Tctex1, and microtubules. After 2 or 4 h VP26+ capsids had moved closer to the cell nucleus, whereas VP26-capsids remained in a random distribution. We propose that VP26 mediates binding of incoming herpes simplex virus capsids to cytoplasmic dynein during cellular infection, through interactions with dynein light chains.

    The Journal of biological chemistry 2004;279;27;28522-30

  • Dynein light chain 1, a p21-activated kinase 1-interacting substrate, promotes cancerous phenotypes.

    Vadlamudi RK, Bagheri-Yarmand R, Yang Z, Balasenthil S, Nguyen D, Sahin AA, den Hollander P and Kumar R

    Department of Molecular and Cellular Oncology, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.

    We identified dynein light chain 1 (DLC1) as a physiologic substrate of p21-activated kinase 1 (Pak1). Pak1-DLC1 interaction plays an essential role in cell survival, which depends on Pak1's phosphorylation of DLC1 on Ser88. Pak1 associates with the complex of DLC1 and BimL, a proapoptotic BH3-only protein, and phosphorylates both proteins. Phosphorylation of BimL by Pak1 prevents it from interacting with and inactivation of Bcl-2, an antiapoptotic protein. Overexpression of DLC1 but not DLC1-Ser88Ala mutant promotes cancerous properties of breast cancer cells. DLC1 protein level is elevated in more than 90% of human breast tumors. The regulation of cell survival functions by Pak1-DLC1 interaction represents a novel mechanism by which a signaling kinase might regulate the cancerous phenotypes.

    Funded by: NCI NIH HHS: CA80066, CA90970

    Cancer cell 2004;5;6;575-85

  • B cell receptor-mediated apoptosis of human lymphocytes is associated with a new regulatory pathway of Bim isoform expression.

    Mouhamad S, Besnault L, Auffredou MT, Leprince C, Bourgeade MF, Leca G and Vazquez A

    Institut National de la Santé et de la Recherche Médicale Unité 542, Villejuif, France.

    Studies in Bim-deficient mice have shown that the proapoptotic molecule Bim plays a key role in the control of B cell homeostasis and activation. However, the role of Bim in human B lymphocyte apoptosis is unknown. We show in this study that, depending on the degree of cross-linking, B cell receptors can mediate both Bim-dependent and apparent Bim-independent apoptotic pathways. Cross-linked anti-mu Ab-mediated activation induces an original pathway governing the expression of the various Bim isoforms. This new pathway involves the following three sequential steps: 1) extracellular signal-regulated kinase-dependent phosphorylation of the BimEL isoform, which is produced in large amounts in healthy B cells; 2) proteasome-mediated degradation of phosphorylated BimEL; and 3) increased expression of the shorter apoptotic isoforms BimL and BimS.

    Journal of immunology (Baltimore, Md. : 1950) 2004;172;4;2084-91

  • Localization of dynein light chains 1 and 2 and their pro-apoptotic ligands.

    Day CL, Puthalakath H, Skea G, Strasser A, Barsukov I, Lian LY, Huang DC and Hinds MG

    Department of Biochemistry, University of Otago, Dunedin, New Zealand.

    The dynein and myosin V motor complexes are multi-protein structures that function to transport molecules and organelles within the cell. DLC (dynein light-chain) proteins, found as components of both dynein and myosin V motor complexes, connect the complexes to their cargoes. One of the roles of these motor complexes is to selectively sequester the pro-apoptotic 'BH3-only' (Bcl-2 homology 3-only) proteins, Bim (Bcl-2-interacting mediator of cell death) and Bmf (Bcl-2-modifying factor), and so regulate their cell death-inducing function. In vivo DLC2 is found exclusively as a component of the myosin V motor complex and Bmf binds DLC2 selectively. On the other hand, Bim interacts with DLC1 (LC8), an integral component of the dynein motor complex. The two DLCs share 93% sequence identity yet show unambiguous in vivo specificity for their respective BH3-only ligands. To investigate this specificity the three-dimensional solution structure of DLC2 was elucidated using NMR spectroscopy. In vitro structural and mutagenesis studies show that Bmf and Bim have identical binding characteristics to recombinant DLC2 or DLC1. Thus the selectivity shown by Bmf and Bim for binding DLC1 or DLC2, respectively, does not reside in their DLC-binding domains. Remarkably, mutational analysis of DLC1 and DLC2 indicates that a single surface residue (residue 41) determines the specific localization of DLCs with their respective motor complexes. These results suggest a molecular mechanism for the specific compartmentalization of DLCs and their pro-apoptotic cargoes and implicate other protein(s) in defining the specificity between the cargoes and the DLC proteins.

    Funded by: NCI NIH HHS: CA 80188

    The Biochemical journal 2004;377;Pt 3;597-605

  • Proteomic identification of brain proteins that interact with dynein light chain LC8.

    Navarro-Lérida I, Martínez Moreno M, Roncal F, Gavilanes F, Albar JP and Rodríguez-Crespo I

    Departamento de Bioquímicay Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain. nacho@bbml.ucm.es

    Cytoplasmic dynein is a large minus end-directed microtubule motor that translocates cargos towards the minus end of microtubules. Light chain 8 of the dynein machinery (LC8) has been reported to interact with a large variety of proteins that possess K/RSTQT or GIQVD motifs in their sequence, hence permitting their transport in a retrograde manner. Yeast two-hybrid analysis has revealed that in brain, LC8 associates directly with several proteins such as neuronal nitric oxide synthase, guanylate kinase domain-associated protein and gephyrin. In this work, we report the identification of over 40 polypeptides, by means of a proteomic approach, that interact with LC8 either directly or indirectly. Many of the neuronal proteins that we identified cluster at the post-synaptic terminal, and some of them such as phosphofructokinase, lactate dehydrogenase or aldolase are directly involved in glutamate metabolism. Other pool of proteins identified displayed the LC8 consensus binding motif. Finally, recombinant LC8 was produced and a library of overlapping dodecapeptides (pepscan) was employed to map the LC8 binding site of some of the proteins that were previously identified using the proteomic approach, hence confirming binding to the consensus binding sites.

    Proteomics 2004;4;2;339-46

  • Identification and characterization of TRP14, a thioredoxin-related protein of 14 kDa. New insights into the specificity of thioredoxin function.

    Jeong W, Yoon HW, Lee SR and Rhee SG

    Laboratory of Cell Signaling, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.

    We have identified and characterized a 14-kDa human thioredoxin (Trx)-related protein designated TRP14. This cytosolic protein was expressed in all tissues and cell types examined, generally in smaller amounts than Trx1. Although TRP14 contains five cysteines, only the two Cys residues in its WCPDC motif were exposed and redox sensitive. Unlike Trx1, which was an equally good substrate for both Trx reductase 1 (TrxR1) and TrxR2, oxidized TRP14 was reduced by TrxR1 but not by TrxR2. Biochemical characterization of TRP14 suggested that, like Trx1, TRP14 is a disulfide reductase; its active site cysteine is sufficiently nucleophilic with the pK(a) value of 6.1; and its redox potential (-257 mV) is similar to those of other cellular thiol reductants. However, although TRP14 reduced small disulfide-containing peptides, it did not reduce the disulfides of known Trx1 substrates, ribonucleotide reductase, peroxiredoxin, and methionine sulfoxide reductase. These results suggest that TRP14 and Trx1 might act on distinct substrate proteins.

    The Journal of biological chemistry 2004;279;5;3142-50

  • Roles of TRP14, a thioredoxin-related protein in tumor necrosis factor-alpha signaling pathways.

    Jeong W, Chang TS, Boja ES, Fales HM and Rhee SG

    Laboratory of Cell Signaling, National Heart, Lung and Bllod Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.

    The possible roles of a 14-kDa human thioredoxin (Trx)-related protein (TRP14) in TNF-alpha signaling were studied in comparison with those of Trx1 by RNA interference in HeLa cells. Depletion of TRP14 augmented the TNF-alpha-induced phosphorylation and degradation of I kappa B alpha as well as the consequent activation of NF-kappa B to a greater extent than did Trx1 depletion. Deficiency of TRP14 or Trx1 enhanced TNF-alpha-induced activation of caspases and subsequent apoptosis by a similar extent. The TNF-alpha-induced activation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPKs), however, was promoted by depletion of TRP14 but not by that of Trx1. Unlike Trx1, TRP14 neither associated with nor inhibited the kinase activity of apoptosis signal-regulating kinase-1 (ASK1), an upstream activator of JNK and p38. In combination with the results in the accompanying paper that TRP14 did not reduce the known substrates of Trx1, these results suggest that TRP14 modulates TNF-alpha signaling pathways, provably by interacting with proteins distinct from the targets of Trx1. In an effort to identify target proteins of TRP14, a mutant of TRP14, in which the active site cysteine (Cys(46)) was substituted with serine, was shown to form a disulfide-linked complex with LC8 cytoplasmic dynein light chain. The complex was detected in HeLa cells treated with H(2)O(2) or TNF-alpha but not in untreated cells, suggesting that LC8 cytoplasmic dynein light chain is a possible substrate of TRP14.

    The Journal of biological chemistry 2004;279;5;3151-9

  • Polo-like kinase 1 regulates Nlp, a centrosome protein involved in microtubule nucleation.

    Casenghi M, Meraldi P, Weinhart U, Duncan PI, Körner R and Nigg EA

    Department of Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18a, D-82152, Martinsried, Germany.

    In animal cells, most microtubules are nucleated at centrosomes. At the onset of mitosis, centrosomes undergo a structural reorganization, termed maturation, which leads to increased microtubule nucleation activity. Centrosome maturation is regulated by several kinases, including Polo-like kinase 1 (Plk1). Here, we identify a centrosomal Plk1 substrate, termed Nlp (ninein-like protein), whose properties suggest an important role in microtubule organization. Nlp interacts with two components of the gamma-tubulin ring complex and stimulates microtubule nucleation. Plk1 phosphorylates Nlp and disrupts both its centrosome association and its gamma-tubulin interaction. Overexpression of an Nlp mutant lacking Plk1 phosphorylation sites severely disturbs mitotic spindle formation. We propose that Nlp plays an important role in microtubule organization during interphase, and that the activation of Plk1 at the onset of mitosis triggers the displacement of Nlp from the centrosome, allowing the establishment of a mitotic scaffold with enhanced microtubule nucleation activity.

    Developmental cell 2003;5;1;113-25

  • Nuclear interaction of the dynein light chain LC8a with the TRPS1 transcription factor suppresses the transcriptional repression activity of TRPS1.

    Kaiser FJ, Tavassoli K, Van den Bemd GJ, Chang GT, Horsthemke B, Möröy T and Lüdecke HJ

    Institut für Humangenetik, Universitätsklinikum, Hufelandstr. 55, D-45122 Essen, Germany.

    The TRPS1 gene codes for a 1281 amino acids nuclear transcription factor with an unusual combination of different types of zinc finger motifs, including GATA-type DNA-binding and IKAROS-like zinc fingers. TRPS1 is a repressor of GATA-regulated genes and implicated in the human tricho-rhino-phalangeal syndromes. We found that two distinct regions of TRPS1 can physically interact with the dynein light chain 8 protein, LC8a, that are at least 458 amino acids apart from each other. Region A covers 89 amino acids (635-723), spanning three potential C(2)H(2) zinc finger structures, and region B covers the 100 most C-terminal amino acids (1182-1281) containing the IKAROS-like motif. LC8a is known to interact with more than 10 different molecules, both proteins and nucleic acids. In most cases, LC8a was identified as a transport molecule in the cytoplasm. Interestingly, we found that LC8a co-localizes with TRPS1 in dot-like structures in the cell nucleus. In an electrophoretic mobility shift assay we could show that the interaction of LC8a and TRPS1 lowers the binding of TRPS1 to the GATA consensus sequence. In addition, GATA-regulated reporter gene assay indicated that LC8a is able to suppress the transcriptional repression activity of TRPS1.

    Human molecular genetics 2003;12;11;1349-58

  • Gene expression profile of the human trabecular meshwork: NEIBank sequence tag analysis.

    Tomarev SI, Wistow G, Raymond V, Dubois S and Malyukova I

    Laboratory of Molecular and Developmental Biology, National Institutes of Health, Bethesda, Maryland 20892-2730, USA. tomarevs@nei.nih.gov

    Purpose: To characterize the gene expression pattern in the human trabecular meshwork (TM) and identify candidate genes for glaucoma by expressed sequence tag (EST) analysis as part of the NEIBank project.

    Methods: RNA was extracted from dissected human TM and used to construct unamplified, un-normalized cDNA libraries in the pSPORT1 vector. More than 4000 clones were sequenced from the 5' end. Clones were clustered and identified using GRIST software. In addition, the expression patterns of genes encoding olfactomedin-domain proteins were analyzed by RT-PCR.

    Results: After non-mRNA contaminants were removed, 3459 independent TM-expressed clones were obtained. These were grouped in 1888 clusters, potentially representing individual expressed genes. Transcripts for the myocilin gene, a locus for inherited glaucoma, formed the third most abundant cluster in the TM collection, and several other genes implicated in glaucoma (PITX2, CYP1B1, and optineurin) were also represented. One abundant TM transcript was from the gene for the angiopoietin-like factor CTD6, which is located at on the long arm of chromosome 1, area 36.2-36.1 in the region of the glaucoma locus GLC3B, whereas other transcripts were from genes close to known glaucoma loci. The TM collection contains cDNAs for genes that are preferentially expressed in the lymphatic endothelium (matrix Gla protein, apolipoprotein D precursor, and selenoprotein P precursor). In addition to EST profiling, RT- PCR was used to detect transcripts of the olfactomedin-domain proteins latrotoxin receptor Lec3 and optimedin in the TM.

    Conclusions: The TM libraries are a good source of molecular markers for TM and candidate genes for glaucoma. The abundance of myocilin cDNAs corresponds to the critical role of this gene in glaucoma and contrasts with libraries derived from cultured tissue. The expression profile raises the possibility that cells of the TM and Schlemm's canal may be more similar to lymphatic, rather than blood vascular endothelium.

    Investigative ophthalmology & visual science 2003;44;6;2588-96

  • JNK phosphorylation of Bim-related members of the Bcl2 family induces Bax-dependent apoptosis.

    Lei K and Davis RJ

    Howard Hughes Medical Institute and Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.

    The c-Jun NH(2)-terminal kinase (JNK) is activated when cells are exposed to environmental stress, including UV radiation. Gene disruption studies demonstrate that JNK is essential for UV-stimulated apoptosis mediated by the mitochondrial pathway by a Bax/Bak-dependent mechanism. Here, we demonstrate that JNK phosphorylates two members of the BH3-only subgroup of Bcl2-related proteins (Bim and Bmf) that are normally sequestered by binding to dynein and myosin V motor complexes. Phosphorylation by JNK causes release from the motor complexes. These proapoptotic BH3-only proteins therefore provide a molecular link between the JNK signal transduction pathway and the Bax/Bak-dependent mitochondrial apoptotic machinery.

    Proceedings of the National Academy of Sciences of the United States of America 2003;100;5;2432-7

  • The heavy chain of conventional kinesin interacts with the SNARE proteins SNAP25 and SNAP23.

    Diefenbach RJ, Diefenbach E, Douglas MW and Cunningham AL

    Centre For Virus Research, Westmead Millennium Institute, Westmead Hospital and The University of Sydney, NSW 2145, Australia. russell_diefenbach@wmi.usyd.edu.au

    Recent studies on the conventional motor protein kinesin have identified a putative cargo-binding domain (residues 827-906) within the heavy chain. To identify possible cargo proteins which bind to this kinesin domain, we employed a yeast two-hybrid assay. A human brain cDNA library was screened, using as bait residues 814-963 of human ubiquitous kinesin heavy chain. This screen initially identified synaptosome-associated protein of 25 kDa (SNAP25) as a kinesin-binding protein. Subsequently, synaptosome-associated protein of 23 kDa (SNAP23), the nonneuronal homologue of SNAP25, was also confirmed to interact with kinesin. The sites of interaction, determined from in vivo and in vitro assays, are the N-terminus of SNAP25 (residues 1-84) and the cargo-binding domain of kinesin heavy chain (residues 814-907). Both regions are composed almost entirely of heptad repeats, suggesting the interaction between heavy chain and SNAP25 is that of a coiled-coil. The observation that SNAP23 also binds to residues 814-907 of heavy chain would indicate that the minimal kinesin-binding domain of SNAP23 and SNAP25 is most likely residues 45-84 (SNAP25 numbering), a heptad-repeat region in both proteins. The major binding site for kinesin light chain in kinesin heavy chain was mapped to residues 789-813 at the C-terminal end of the heavy chain stalk domain. Weak binding of light chain was also detected at the N-terminus of the heavy chain tail domain (residues 814-854). In support of separate binding sites on heavy chain for light chain and SNAPs, a complex of heavy and light chains was observed to interact with SNAP25 and SNAP23.

    Biochemistry 2002;41;50;14906-15

  • Centrosomal proteins CG-NAP and kendrin provide microtubule nucleation sites by anchoring gamma-tubulin ring complex.

    Takahashi M, Yamagiwa A, Nishimura T, Mukai H and Ono Y

    Biosignal Research Center, Kobe University, Japan.

    Microtubule assembly is initiated by the gamma-tubulin ring complex (gamma-TuRC). In yeast, the microtubule is nucleated from gamma-TuRC anchored to the amino-terminus of the spindle pole body component Spc110p, which interacts with calmodulin (Cmd1p) at the carboxy-terminus. However, mammalian protein that anchors gamma-TuRC remains to be elucidated. A giant coiled-coil protein, CG-NAP (centrosome and Golgi localized PKN-associated protein), was localized to the centrosome via the carboxyl-terminal region. This region was found to interact with calmodulin by yeast two-hybrid screening, and it shares high homology with the carboxyl-terminal region of another centrosomal coiled-coil protein, kendrin. The amino-terminal region of either CG-NAP or kendrin indirectly associated with gamma-tubulin through binding with gamma-tubulin complex protein 2 (GCP2) and/or GCP3. Furthermore, endogenous CG-NAP and kendrin were coimmunoprecipitated with each other and with endogenous GCP2 and gamma-tubulin, suggesting that CG-NAP and kendrin form complexes and interact with gamma-TuRC in vivo. These proteins were localized to the center of microtubule asters nucleated from isolated centrosomes. Pretreatment of the centrosomes by antibody to CG-NAP or kendrin moderately inhibited the microtubule nucleation; moreover, the combination of these antibodies resulted in stronger inhibition. These results imply that CG-NAP and kendrin provide sites for microtubule nucleation in the mammalian centrosome by anchoring gamma-TuRC.

    Molecular biology of the cell 2002;13;9;3235-45

  • Gephyrin interacts with Dynein light chains 1 and 2, components of motor protein complexes.

    Fuhrmann JC, Kins S, Rostaing P, El Far O, Kirsch J, Sheng M, Triller A, Betz H and Kneussel M

    Max-Planck-Institute for Brain Research, Department of Neurochemistry, D-60528 Frankfurt/Main, Germany.

    The clustering of glycine receptors and major subtypes of GABA(A) receptors at inhibitory synapses is mediated by the tubulin-binding protein gephyrin. In an attempt to identify additional components of inhibitory postsynaptic specializations, we performed a yeast two-hybrid screen using gephyrin as bait. Multiple positive clones encoded either the dynein light chain-1 (Dlc-1), also known as dynein LC8 and protein inhibitor of neuronal nitric oxide synthase, or its homolog Dlc-2. Dlc-1 protein bound efficiently to gephyrin in in vitro binding assays and colocalized with gephyrin during coexpression in HEK293 cells. The binding site for Dlc was mapped to a fragment of 63 amino acids within the central linker domain of gephyrin. In hippocampal neurons, endogenous Dlc protein was enriched at synaptic sites identified by synaptophysin and gephyrin immunostaining. Immunoelectron microscopy in spinal cord sections revealed Dlc immunoreactivity at the edges of postsynaptic differentiations, in close contact with cytoskeletal structures and at the periphery of the Golgi apparatus. Because Dlc-1 and Dlc-2 have been described as stoichiometric components of cytoplasmic dynein and myosin-Va complexes, our results suggest that motor proteins are involved in the subcellular localization of gephyrin.

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2002;22;13;5393-402

  • Protein inhibitor of neuronal nitric oxide synthase interacts with protein kinase A inhibitors.

    Yu J, Yu L, Chen Z, Zheng L, Chen X, Wang X, Ren D and Zhao S

    State Key Laboratory of Genetics Engineering, Institute of Genetics, School of Life Science, Fudan University, 220 Handan Road, Shanghai 200433, PR China.

    Protein kinase A (PKA) and neuronal nitric oxide synthase (nNOS) are important signaling molecules. It is well known that PKA can specifically phosphorylate nNOS. But the underlying molecular mechanism is still obscure. Our data indicate that the protein inhibitor of nNOS (PIN) binds to protein kinase A inhibitors (PKIs), which suggests that PKIs, together with PIN, might mediate the phosphorylation of nNOS by PKA.

    Brain research. Molecular brain research 2002;99;2;145-9

  • The 8-kDa dynein light chain binds to its targets via a conserved (K/R)XTQT motif.

    Lo KW, Naisbitt S, Fan JS, Sheng M and Zhang M

    Department of Biochemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.

    Cytoplasmic dynein is a large, multisubunit molecular motor that translocates cargoes toward the minus ends of microtubules. Proper functioning of the dynein motor requires precise assembly of its various subunits. Using purified recombinant proteins, we show that the highly conserved 8-kDa light chain (DLC8) binds to the intermediate chain of the dynein complex. The DLC8-binding region was mapped to a highly conserved 10-residue fragment (amino acid sequence SYSKETQTPL) C-terminal to the second alternative splicing site of dynein intermediate chain. Yeast two-hybrid screening using DLC8 as bait identified numerous additional DLC8-binding proteins. Biochemical and mutational analysis of selected DLC8-binding proteins revealed that DLC8 binds to a consensus sequence containing a (K/R)XTQT motif. The (K/R)XTQT motif interacts with the common target-accepting grooves of DLC8 dimer. The role of each conserved amino acid residue in this pentapeptide motif in supporting complex formation with DLC8 was systematically studied using site-directed mutagenesis.

    The Journal of biological chemistry 2001;276;17;14059-66

  • The small GTPase Rab4A interacts with the central region of cytoplasmic dynein light intermediate chain-1.

    Bielli A, Thörnqvist PO, Hendrick AG, Finn R, Fitzgerald K and McCaffrey MW

    Cell & Molecular Biology Laboratory, University College Cork, Ireland.

    Rab4 belongs to the Rab family of small GTPases involved in the regulation of intracellular transport, and has been localized to early endosomes. We have employed the yeast two-hybrid system to identify proteins that specifically interact with Rab4AQ67L, a GTPase-deficient mutant form of Rab4A. Screening a mouse embryo cDNA library identified a clone (M449) that interacted with Rab4A in a nucleotide-dependent fashion. Data base searches identified this clone as the mouse cytoplasmic dynein light intermediate chain-1 (LIC-1). Based on this finding, the full-length equivalent human cytoplasmic dynein LIC-1 was isolated by PCR. When Rab4A was overexpressed together with either M449 or dynein LIC-1 in HeLa cells, the proteins were found to colocalize in the perinuclear region. We characterize the localization of both overexpressed human dynein LIC-1 and the endogenous protein with respect to microtubules and show that it concentrates to the microtubule-organizing center and mitotic spindle. Additionally, GFPRab4A endosomes localize to microtubules and are redistributed by nocodazole treatment. This is the first described interaction between cytoplasmic dynein, a retrograde motor protein, and a Rab protein.

    Biochemical and biophysical research communications 2001;281;5;1141-53

  • Structural basis of diverse sequence-dependent target recognition by the 8 kDa dynein light chain.

    Fan J, Zhang Q, Tochio H, Li M and Zhang M

    Department of Biochemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, Kowloon, P. R. China.

    Dyneins are multi-subunit molecular motors that translocate molecular cargoes along microtubules. Other than acting as an essential component of the dynein motor complex, the 89-residue subunit of dynein light chain (DLC8) also regulates a number of other biological events by binding to various proteins and enzymes. Currently known DLC8 targets include neuronal nitric oxide synthase; the proapoptotic Bcl-2 family member protein designated Bim; a Drosophila RNA localization protein Swallow, myosin V, neuronal scaffolding protein GKAP, and IkappaBalpha, an inhibitor of the NFkappaB transcription factor. The DLC8-binding domains of the various targets are confined within a short, continuous stretch of amino acid residues. However, these domains do not share any obvious sequence homology with each other. Here, the three-dimensional structures of DLC8 complexed with two peptides corresponding to the DLC8-binding domains of neuronal nitric oxide synthase and Bim, respectively, were determined by NMR spectroscopy. Although the two DLC8-binding peptides have entirely different amino acid sequences, both peptides bind to the protein with a remarkable similar conformation by engaging the symmetric DLC8 dimer through antiparallel beta-sheet augmentation via the beta2 strand of the protein. Structural comparison indicates that the two target peptides use different regions within the conformational flexible peptide-binding channels to achieve binding specificity. We have also re-determined the apo-form solution structure of DLC8 in this work. The structures of the DLC8/target peptide complexes, together with the dynamic properties of the protein, provide a molecular basis of DLC8's diverse amino acid sequence-dependent target recognition.

    Journal of molecular biology 2001;306;1;97-108

  • Association of Trk neurotrophin receptors with components of the cytoplasmic dynein motor.

    Yano H, Lee FS, Kong H, Chuang J, Arevalo J, Perez P, Sung C and Chao MV

    Molecular Neurobiology Program, Skirball Institute for Biomolecular Medicine, Departments of Cell Biology , New York, New York 10016, USA.

    Nerve growth factor (NGF) initiates its trophic effects by long-range signaling through binding, internalization, and transport of a ligand-receptor complex from the axon terminal to the cell body. However, the mechanism by which retrograde transport of NGF takes place has not been elucidated. Here we describe an interaction between the Trk receptor tyrosine kinase and a 14 kDa light chain of cytoplasmic dynein. After transfection in human embryonic kidney 293 cells, this 14 kDa dynein light chain was found to bind to TrkA, TrkB, and TrkC receptors. Mapping experiments indicated that the 14 kDa dynein light chain binds to the distal region of the TrkA juxtamembrane domain. Coimmunoprecipitation experiments in vivo indicate that Trk receptors are in a complex with the 14 kDa light chain and 74 kDa intermediate chain of dynein. Confirming the physiological relevance of this association, a marked accumulation of Trk with the 14 kDa and the 74 kDa dynein components was observed after ligation of the sciatic nerve. The association of Trk receptors with components of cytoplasmic dynein suggests that transport of neurotrophins during vesicular trafficking may occur through a direct interaction of the Trk receptor with the dynein motor machinery.

    Funded by: NEI NIH HHS: EY11307, R01 EY011307; NICHD NIH HHS: HD233-5; NINDS NIH HHS: NS21072

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2001;21;3;RC125

  • Dynein light chain interacts with NRF-1 and EWG, structurally and functionally related transcription factors from humans and drosophila.

    Herzig RP, Andersson U and Scarpulla RC

    Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA.

    Nuclear respiratory factor-1 is a transcriptional activator that has been implicated in the nuclear control of respiratory chain expression. Yeast two-hybrid screens were performed to identify proteins that physically interact with nuclear respiratory factor-1. Saturation screening of both mouse embryo and mouse testis libraries yielded 14 independent clones, all of which represented two different isoforms of dynein light chain. In addition to using the two-hybrid method, the specificity of the nuclear respiratory factor-1/dynein light chain interaction was established by chemical crosslinking of the purified native proteins and by co-immunoprecipitation of nuclear respiratory factor-1 and dynein light chain from mammalian cells. Both two-hybrid and chemical crosslinking assays demonstrated that binding of dynein light chain required the first 26 amino acids of nuclear respiratory factor-1. Although dynein light chain is associated with dynein, a cytoplasmic motor molecule, immunolocalizations showed substantial nuclear staining using several different anti-dynein light chain antibodies. Moreover, fluorescence overlays of confocal images established that nuclear respiratory factor-1 and dynein light chain displayed a very similar nuclear staining pattern. The significance of the nuclear respiratory factor-1/dynein light chain interaction was investigated further by determining whether a similar interaction was conserved between dynein light chain and the erect wing gene product of Drosophila, a protein related to nuclear respiratory factor-1 through its DNA binding domain. Here, we establish that the erect wing gene product can bind and trans-activate transcription through authentic nuclear respiratory factor-1 binding sites. Moreover, the erect wing gene product, like nuclear respiratory factor-1, interacted specifically with dynein light chain both in vitro and in transfected cells. Thus, the interaction with dynein light chain is conserved between transcription factors that are structurally and functionally similar between humans and Drosophila.

    Journal of cell science 2000;113 Pt 23;4263-73

  • The centrosomal protein C-Nap1 is required for cell cycle-regulated centrosome cohesion.

    Mayor T, Stierhof YD, Tanaka K, Fry AM and Nigg EA

    Department of Molecular Biology, Sciences II, University of Geneva, CH-1211 Geneva, Switzerland.

    Duplicating centrosomes are paired during interphase, but are separated at the onset of mitosis. Although the mechanisms controlling centrosome cohesion and separation are important for centrosome function throughout the cell cycle, they remain poorly understood. Recently, we have proposed that C-Nap1, a novel centrosomal protein, is part of a structure linking parental centrioles in a cell cycle-regulated manner. To test this model, we have performed a detailed structure-function analysis on C-Nap1. We demonstrate that antibody-mediated interference with C-Nap1 function causes centrosome splitting, regardless of the cell cycle phase. Splitting occurs between parental centrioles and is not dependent on the presence of an intact microtubule or microfilament network. Centrosome splitting can also be induced by overexpression of truncated C-Nap1 mutants, but not full-length protein. Antibodies raised against different domains of C-Nap1 prove that this protein dissociates from spindle poles during mitosis, but reaccumulates at centrosomes at the end of cell division. Use of the same antibodies in immunoelectron microscopy shows that C-Nap1 is confined to the proximal end domains of centrioles, indicating that a putative linker structure must contain additional proteins. We conclude that C-Nap1 is a key component of a dynamic, cell cycle-regulated structure that mediates centriole-centriole cohesion.

    The Journal of cell biology 2000;151;4;837-46

  • The hDLG-associated protein DAP interacts with dynein light chain and neuronal nitric oxide synthase.

    Haraguchi K, Satoh K, Yanai H, Hamada F, Kawabuchi M and Akiyama T

    Laboratory of Molecular and Genetic Information, Institute for Molecular and Cellular Biosciences, The University of Tokyo, Japan.

    Background: Postsynaptic density (PSD)-95 interacts with and mediates clustering of the N-methyl-D-aspartate-receptors (NMDA-R). PSD-95 also interacts with the hDLG-associated protein DAP, which is also called Synapse-associated protein 90-associated protein (SAPAP), and Guanylate kinase-associated protein (GKAP).

    Results: DAP interacted directly with the dynein light chain (DLC) family of proteins. DLC was contained in the NMDA-R-PSD-95-DAP-neuronal nitric oxide synthase (nNOS) complex. Furthermore, DAP interacted with nNOS and recruited it into the Triton X-100-insoluble fraction of transfected cells.

    Conclusion: DAP interacts directly with DLC and nNOS, and links these proteins to the NMDA-R-PSD-95 complex.

    Genes to cells : devoted to molecular & cellular mechanisms 2000;5;11;905-911

  • Cytoplasmic dynein LC8 interacts with lyssavirus phosphoprotein.

    Jacob Y, Badrane H, Ceccaldi PE and Tordo N

    Laboratoire des Lyssavirus, Institut Pasteur, 75724 Paris Cedex 15, France. yjacob@pasteur.fr

    Using a yeast two-hybrid human brain cDNA library screen, the cytoplasmic dynein light chain (LC8), a 10-kDa protein, was found to interact strongly with the phosphoprotein (P) of two lyssaviruses: rabies virus (genotype 1) and Mokola virus (genotype 3). The high degree of sequence divergence between these P proteins (only 46% amino acid identity) favors the hypothesis that this interaction is a common property shared by all lyssaviruses. The P protein-dynein LC8 interaction was confirmed by colocalization with laser confocal microscopy in infected cells and by coimmunoprecipitation. The dynein-interacting P protein domain was mapped to the 186 amino acid residues of the N-terminal half of the protein. Dynein LC8 is a component of both cytoplasmic dynein and myosin V, which are involved in a wide range of intracellular motile events, such as microtubule minus-end directed organelle transport in axon "retrograde transport" and actin-based vesicle transport, respectively. Our results provide support for a model of viral nucleocapsid axoplasmic transport. Furthermore, the role of LC8 in cellular mechanisms other than transport, e.g., inhibition of neuronal nitric oxide synthase, suggests that the P protein interactions could be involved in physiopathological mechanisms of rabies virus-induced pathogenesis.

    Journal of virology 2000;74;21;10217-22

  • Interaction of the postsynaptic density-95/guanylate kinase domain-associated protein complex with a light chain of myosin-V and dynein.

    Naisbitt S, Valtschanoff J, Allison DW, Sala C, Kim E, Craig AM, Weinberg RJ and Sheng M

    Howard Hughes Medical Institute, Department of Neurobiology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA.

    NMDA receptors interact directly with postsynaptic density-95 (PSD-95), a scaffold protein that organizes a cytoskeletal- signaling complex at the postsynaptic membrane. The molecular mechanism by which the PSD-95-based protein complex is trafficked to the postsynaptic site is unknown but presumably involves specific motor proteins. Here we demonstrate a direct interaction between the PSD-95-associated protein guanylate kinase domain-associated protein (GKAP) and dynein light chain (DLC), a light chain subunit shared by myosin-V (an actin-based motor) and cytoplasmic dynein (a microtubule-based motor). A yeast two-hybrid screen with GKAP isolated DLC2, a novel protein 93% identical to the previously cloned 8 kDa dynein light chain (DLC1). A complex containing PSD-95, GKAP, DLC, and myosin-V can be immunoprecipitated from rat brain extracts. DLC colocalizes with PSD-95 and F-actin in dendritic spines of cultured neurons and is enriched in biochemical purifications of PSD. Immunogold electron microscopy reveals a concentration of DLC in the postsynaptic compartment of asymmetric synapses of brain in which it is associated with the PSD and the spine apparatus. We discuss the possibility that the GKAP/DLC interaction may be involved in trafficking of the PSD-95 complex by motor proteins.

    Funded by: NINDS NIH HHS: NS29879, NS33184, NS35050

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2000;20;12;4524-34

  • Dynein light chain binding to a 3'-untranslated sequence mediates parathyroid hormone mRNA association with microtubules.

    Epstein E, Sela-Brown A, Ringel I, Kilav R, King SM, Benashski SE, Yisraeli JK, Silver J and Naveh-Many T

    Minerva Center for Calcium and Bone Metabolism, Nephrology Services, Hadassah University Hospital, Jerusalem, Israel 91120.

    The 3'-untranslated region (UTR) of mRNAs binds proteins that determine mRNA stability and localization. The 3'-UTR of parathyroid hormone (PTH) mRNA specifically binds cytoplasmic proteins. We screened an expression library for proteins that bind the PTH mRNA 3'-UTR, and the sequence of 1 clone was identical to that of the dynein light chain LC8, a component of the dynein complexes that translocate cytoplasmic components along microtubules. Recombinant LC8 binds PTH mRNA 3'-UTR, as shown by RNA electrophoretic mobility shift assay. We showed that PTH mRNA colocalizes with microtubules in the parathyroid gland, as well as with a purified microtubule preparation from calf brain, and that this association was mediated by LC8. To our knowledge, this is the first report of a dynein complex protein binding an mRNA. The dynein complex may be the motor that is responsible for transporting mRNAs to specific locations in the cytoplasm and for the consequent is asymmetric distribution of translated proteins in the cell.

    Funded by: NHLBI NIH HHS: HL-54591; NIGMS NIH HHS: R01 GM051293

    The Journal of clinical investigation 2000;105;4;505-12

  • Structure of the PIN/LC8 dimer with a bound peptide.

    Liang J, Jaffrey SR, Guo W, Snyder SH and Clardy J

    Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA.

    The structure of the protein known both as neuronal nitric oxide synthase inhibitory protein, PIN (protein inhibitor of nNOS), and also as the 8 kDa dynein light chain (LC8) has been solved by X-ray diffraction. Two PIN/LC8 monomers related by a two-fold axis form a rectangular dimer. Two pairs of alpha-helices cover opposite faces, and each pair of helices packs against a beta-sheet with five antiparallel beta-strands. Each five-stranded beta-sheet contains four strands from one monomer and a fifth strand from the other monomer. A 13-residue peptide from nNOS is bound to the dimer in a deep hydrophobic groove as a sixth antiparallel beta-strand. The structure provides key insights into dimerization of and peptide binding by the multifunctional PIN/LC8 protein.

    Nature structural biology 1999;6;8;735-40

  • The proapoptotic activity of the Bcl-2 family member Bim is regulated by interaction with the dynein motor complex.

    Puthalakath H, Huang DC, O'Reilly LA, King SM and Strasser A

    Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Victoria, Australia.

    Bcl-2 family members that have only a single Bcl-2 homology domain, BH3, are potent inducers of apoptosis, and some appear to play a critical role in developmentally programmed cell death. We examined the regulation of the proapoptotic activity of the BH3-only protein Bim. In healthy cells, most Bim molecules were bound to LC8 cytoplasmic dynein light chain and thereby sequestered to the microtubule-associated dynein motor complex. Certain apoptotic stimuli disrupted the interaction between LC8 and the dynein motor complex. This freed Bim to translocate together with LC8 to Bcl-2 and to neutralize its antiapoptotic activity. This process did not require caspase activity and therefore constitutes an initiating event in apoptosis signaling.

    Funded by: NIGMS NIH HHS: GM51293

    Molecular cell 1999;3;3;287-96

  • Protein inhibitor of neuronal nitric-oxide synthase, PIN, binds to a 17-amino acid residue fragment of the enzyme.

    Fan JS, Zhang Q, Li M, Tochio H, Yamazaki T, Shimizu M and Zhang M

    Department of Biochemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China.

    Neuronal nitric-oxide synthase (nNOS) is the primary nitric oxide (NO) regulator in neurons. The activity of the enzyme is inhibited by a protein inhibitor called PIN. We were able to purify large quantities of PIN overexpressed in bacterial cells. Analytical ultracentrifugation and chemical cross-linking studies showed that PIN exists as a monomer at low concentrations. The protein forms a high order aggregate at elevated concentrations. We have shown, using NMR spectroscopy, that the previously identified PIN-binding domain (PINB) of nNOS (residues 161-245) adopts a random coil structure in solution. By titrating 15N-labeled PINB with unlabeled PIN, the PIN-binding region of nNOS was precisely mapped to a 17-residue peptide fragment from Met-228 to His-244 of nNOS. NMR titration experiments also showed that PIN binds to nNOS with a 1:2 stoichiometry. A synthetic peptide corresponding to the identified PIN-binding region of nNOS was used to study the interaction between PIN and nNOS in detail. The functional implications of the results obtained from this study are discussed.

    The Journal of biological chemistry 1998;273;50;33472-81

  • Binding of dynein light chain (PIN) to neuronal nitric oxide synthase in the absence of inhibition.

    Rodríguez-Crespo I, Straub W, Gavilanes F and Ortiz de Montellano PR

    Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, 28040, Spain.

    PIN, an 89-amino-acid polypeptide found in a rat hippocampal cDNA library using the yeast two-hybrid system and various neuronal nitric oxide synthase (nNOS) fragments as bait, was reported to be an inhibitor of nNOS (Science 274, 774-778, 1996). PIN reportedly inhibited nNOS selectively and did not interact with either the endothelial or inducible nitric oxide synthase isoforms. Inhibition was attributed to the ability of PIN to dissociate the catalytically active nNOS homodimer. PIN is a dynein light chain (J. Biol. Chem. 271, 19358-19366, 1996), which suggested that PIN may serve as an axonal transport protein for nNOS. We have synthesized a rat PIN cDNA by recursive polymerase chain reaction and have expressed the protein in Escherichia coli. Recombinant PIN is a folded dimeric, mostly alpha-helical protein with a single deeply buried tryptophan residue. We have also expressed and purified the nNOS fragment to which PIN reportedly binds (residues 163-245). This recombinant peptide has a disordered secondary structure. Gel-filtration experiments show that PIN binds to both the full-length nNOS and nNOS fragment. However, PIN neither inhibits nNOS activity nor dissociates the nNOS dimer into monomeric species. PIN thus possibly functions as a dynein light chain involved in nNOS axonal transport but is not an inhibitor of the enzyme. Our results agree with the proposal (Cell 82, 743-752, 1995) that the PIN recognition sequence in nNOS both lies outside the catalytic core and is not part of the monomer-monomer contact region.

    Funded by: NIGMS NIH HHS: GM25515

    Archives of biochemistry and biophysics 1998;359;2;297-304

  • Solution structure of a protein inhibitor of neuronal nitric oxide synthase.

    Tochio H, Ohki S, Zhang Q, Li M and Zhang M

    Department of Biochemistry, The Hong Kong University of Science and Technology, Kowloon, P.R. China.

    The structure of the neuronal nitric oxide synthase inhibitory protein, PIN (protein inhibitor of nNOS), has been determined by NMR spectroscopy. Two N-terminal antiparallel alpha-helices pack against a four-stranded antiparallel beta-sheet in the C-terminal region of the protein, forming a two-layer alpha/beta plait. The three dimensional structure of PIN resembles the fold of the B-chain of aspartylglucosaminidase. A non-prolyl cis peptide bond was found between Pro 52 and Thr 53 of the protein. PIN has a large solvent-exposed hydrophobic surface that contains a cavity and is rimmed with positive charges. This surface may serve as the primary target-binding region for this multi-functional regulatory protein.

    Nature structural biology 1998;5;11;965-9

  • I kappaB alpha physically interacts with a cytoskeleton-associated protein through its signal response domain.

    Crépieux P, Kwon H, Leclerc N, Spencer W, Richard S, Lin R and Hiscott J

    Terry Fox Molecular Oncology Group, Lady Davis Institute for Medical Research, Department of Medicine, McGill University, Montreal, Que., Canada.

    The I kappaB alpha protein is a key molecular target involved in the control of NF-kappaB/Rel transcription factors during viral infection or inflammatory reactions. This NF-kappaB-inhibitory factor is regulated by posttranslational phosphorylation and ubiquitination of its amino-terminal signal response domain that targets I kappaB alpha for rapid proteolysis by the 26S proteasome. In an attempt to identify regulators of the I kappaB alpha inhibitory activity, we undertook a yeast two-hybrid genetic screen, using the amino-terminal end of I kappaB alpha as bait, and identified 12 independent interacting clones. Sequence analysis identified some of these cDNA clones as Dlc-1, a sequence encoding a small, 9-kDa human homolog of the outer-arm dynein light-chain protein. In the two-hybrid assay, Dlc-1 also interacted with full-length I kappaB alpha protein but not with N-terminal-deletion-containing versions of I kappaB alpha. I kappaB alpha interacted in vitro with a glutathione S-transferase-Dlc-1 fusion protein, and RelA(p65) did not displace this association, demonstrating that p65 and Dlc-1 contact different protein motifs of I kappaB alpha. Importantly, in HeLa and 293 cells, endogenous and transfected I kappaB alpha coimmunoprecipitated with Myc-tagged or endogenous Dlc-1. Indirect immunofluorescence analyzed by confocal microscopy indicated that Dlc-1 and I kappaB alpha colocalized with both nuclear and cytoplasmic distribution. Furthermore, Dlc-1 and I kappaB alpha were found to associate with the microtubule organizing center, a perinuclear region from which microtubules radiate. Likewise, I kappaB alpha colocalized with alpha-tubulin filaments. Taken together, these results highlight an intriguing interaction between the I kappaB alpha protein and the human homolog of a member of the dynein family of motor proteins and provide a potential link between cytoskeleton dynamics and gene regulation.

    Molecular and cellular biology 1997;17;12;7375-85

  • PIN: an associated protein inhibitor of neuronal nitric oxide synthase.

    Jaffrey SR and Snyder SH

    Department of Neuroscience, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.

    The neurotransmitter functions of nitric oxide are dependent on dynamic regulation of its biosynthetic enzyme, neuronal nitric oxide synthase (nNOS). By means of a yeast two-hybrid screen, a 10-kilodalton protein was identified that physically interacts with and inhibits the activity of nNOS. This inhibitor, designated PIN, appears to be one of the most conserved proteins in nature, showing 92 percent amino acid identity with the nematode and rat homologs. Binding of PIN destabilizes the nNOS dimer, a conformation necessary for activity. These results suggest that PIN may regulate numerous biological processes through its effects on nitric oxide synthase activity.

    Funded by: NIDA NIH HHS: DA00074; NIGMS NIH HHS: GM-07309

    Science (New York, N.Y.) 1996;274;5288;774-7

  • Cytoplasmic dynein (ddlc1) mutations cause morphogenetic defects and apoptotic cell death in Drosophila melanogaster.

    Dick T, Ray K, Salz HK and Chia W

    Institute of Molecular and Cell Biology, National University of Singapore.

    We report the molecular and genetic characterization of the cytoplasmic dynein light-chain gene, ddlc1, from Drosophila melanogaster. ddlc1 encodes the first cytoplasmic dynein light chain identified, and its genetic analysis represents the first in vivo characterization of cytoplasmic dynein function in higher eucaryotes. The ddlc1 gene maps to 4E1-2 and encodes an 89-amino-acid polypeptide with a high similarity to the axonemal 8-kDa outer-arm dynein light chain from Chlamydomonas flagella. Developmental Northern (RNA) blot analysis and ovary and embryo RNA in situ hybridizations indicate that the ddlc1 gene is expressed ubiquitously. Anti-DDLC1 antibody analyses show that the DDLC1 protein is localized in the cytoplasm. P-element-induced partial-loss-of-function mutations cause pleiotropic morphogenetic defects in bristle and wing development, as well as in oogenesis, and hence result in female sterility. The morphological abnormalities found in the ovaries are always associated with a loss of cellular shape and structure, as visualized by a disorganization of the actin cytoskeleton. Total-loss-of-function mutations cause lethality. A large proportion of mutant animals degenerate during embryogenesis, and the dying cells show morphological changes characteristic of apoptosis, namely, cell and nuclear condensation and fragmentation, as well as DNA degradation. Cloning of the human homolog of the ddlc1 gene, hdlc1, demonstrates that the dynein light-chain 1 is highly conserved in flies and humans. Northern blot analysis and epitope tagging show that the hdlc1 gene is ubiquitously expressed and that the human dynein light chain 1 is localized in the cytoplasm. hdlc1 maps to 14q24.

    Molecular and cellular biology 1996;16;5;1966-77

  • Cell cycle regulation of the activity and subcellular localization of Plk1, a human protein kinase implicated in mitotic spindle function.

    Golsteyn RM, Mundt KE, Fry AM and Nigg EA

    Swiss Institute for Experimental Cancer Research (ISREC), Epalinges.

    Correct assembly and function of the mitotic spindle during cell division is essential for the accurate partitioning of the duplicated genome to daughter cells. Protein phosphorylation has long been implicated in controlling spindle function and chromosome segregation, and genetic studies have identified several protein kinases and phosphatases that are likely to regulate these processes. In particular, mutations in the serine/threonine-specific Drosophila kinase polo, and the structurally related kinase Cdc5p of Saccharomyces cerevisae, result in abnormal mitotic and meiotic divisions. Here, we describe a detailed analysis of the cell cycle-dependent activity and subcellular localization of Plk1, a recently identified human protein kinase with extensive sequence similarity to both Drosophila polo and S. cerevisiae Cdc5p. With the aid of recombinant baculoviruses, we have established a reliable in vitro assay for Plk1 kinase activity. We show that the activity of human Plk1 is cell cycle regulated, Plk1 activity being low during interphase but high during mitosis. We further show, by immunofluorescent confocal laser scanning microscopy, that human Plk1 binds to components of the mitotic spindle at all stages of mitosis, but undergoes a striking redistribution as cells progress from metaphase to anaphase. Specifically, Plk1 associates with spindle poles up to metaphase, but relocalizes to the equatorial plane, where spindle microtubules overlap (the midzone), as cells go through anaphase. These results indicate that the association of Plk1 with the spindle is highly dynamic and that Plk1 may function at multiple stages of mitotic progression. Taken together, our data strengthen the notion that human Plk1 may represent a functional homolog of polo and Cdc5p, and they suggest that this kinase plays an important role in the dynamic function of the mitotic spindle during chromosome segregation.

    The Journal of cell biology 1995;129;6;1617-28

  • Isolation of novel and known genes from a human fetal cochlear cDNA library using subtractive hybridization and differential screening.

    Robertson NG, Khetarpal U, Gutiérrez-Espeleta GA, Bieber FR and Morton CC

    Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115.

    We used a combination of subtractive hybridization and differential screening strategies to identify genes that may function normally in hearing and, when mutated, result in deafness. A human fetal cochlear (membranous labyrinth) cDNA library was subtracted against total human fetal brain RNAs by an avidin-biotin-based procedure to enrich for cochlear transcripts. Subtracted cochlear clones were differentially screened with 32P-labeled total cochlear and total brain cDNA probes. Sequence analysis of clones that hybridized more intensely with cochlear than with brain cDNA probes revealed some previously characterized genes, including mitochondrial sequences, collagen type I alpha-2 (COL1A2), collagen type II alpha-1 (COL2A1), collagen type III alpha-1 (COL3A1), spermidine/spermine N1-acetyltransferase (SAT), osteonectin (SPARC), and peripheral myelin protein 22 (PMP22). Also identified were clones that are potential novel cochlear genes. Northern blots of cochlear and brain RNAs probed with COL1A2, COL2A1, COL3A1, SAT, SPARC, PMP22, and a novel sequence, designated Coch-5B2, confirm results of the subtractive procedure by showing preferential cochlear expression. A number of these genes serve structural or regulatory functions in extracellular matrix or neural conduction; defects in some of these genes are associated with disorders involving hearing loss. Partial sequence analysis of Coch-5B2 reveals a von Willebrand factor type A-like domain in this cDNA. To assess the cochlear specificity of Coch-5B2, a Northern blot panel of 14 human fetal tissue RNAs was probed with Coch-5B2, showing differential expression of this novel gene in the cochlea.

    Funded by: NHLBI NIH HHS: T32 HL07627; NIDCD NIH HHS: DC00871

    Genomics 1994;23;1;42-50

Gene lists (6)

Gene List Source Species Name Description Gene count
L00000009 G2C Homo sapiens Human PSD Human orthologues of mouse PSD adapted from Collins et al (2006) 1080
L00000016 G2C Homo sapiens Human PSP Human orthologues of mouse PSP adapted from Collins et al (2006) 1121
L00000059 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-CONSENSUS Human cortex PSD consensus 748
L00000061 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus (ortho) 984
L00000069 G2C Homo sapiens BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list 1461
L00000071 G2C Homo sapiens BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list (ortho) 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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