G2Cdb::Gene report

Gene id
G00000957
Gene symbol
Bsn (MGI)
Species
Mus musculus
Description
bassoon
Orthologue
G00002206 (Homo sapiens)

Databases (11)

Curated Gene
OTTMUSG00000016899 (Vega mouse gene)
Gene
ENSMUSG00000032589 (Ensembl mouse gene)
12217 (Entrez Gene)
85 (G2Cdb plasticity & disease)
Gene Expression
NM_007567 (Allen Brain Atlas)
g00409 (BGEM)
12217 (Genepaint)
bsn (gensat)
Literature
604020 (OMIM)
Marker Symbol
MGI:1277955 (MGI)
Protein Sequence
O88737 (UniProt)

Synonyms (1)

  • presynaptic cytomatrix protein

Literature (41)

Pubmed - other

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

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

    Telethon Institute of Genetics and Medicine, Naples, Italy.

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

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

    PLoS biology 2011;9;1;e1000582

  • Calcium channels link the muscle-derived synapse organizer laminin β2 to Bassoon and CAST/Erc2 to organize presynaptic active zones.

    Chen J, Billings SE and Nishimune H

    Department of Anatomy and Cell Biology and Kansas Intellectual and Developmental Disabilities Research Center, University of Kansas Medical School, Kansas City, Kansas 66160, USA.

    Synapse formation requires the organization of presynaptic active zones, the synaptic vesicle release sites, in precise apposition to postsynaptic neurotransmitter receptor clusters; however, the molecular mechanisms responsible for these processes remain unclear. Here, we show that P/Q-type and N-type voltage-dependent calcium channels (VDCCs) play essential roles as scaffolding proteins in the organization of presynaptic active zones. The neuromuscular junction of double knock-out mice for P/Q- and N-type VDCCs displayed a normal size but had significantly reduced numbers of active zones and docked vesicles and featured an attenuation of the active-zone proteins Bassoon, Piccolo, and CAST/Erc2. Consistent with this phenotype, direct interactions of the VDCC β1b or β4 subunits and the active zone-specific proteins Bassoon or CAST/Erc2 were confirmed by immunoprecipitation. A decrease in the number of active zones caused by a loss of presynaptic VDCCs resembled the pathological conditions observed in the autoimmune neuromuscular disorder Lambert-Eaton myasthenic syndrome. At the synaptic cleft of double knock-out mice, we also observed a decrease of the synaptic organizer laminin β2 protein, an extracellular ligand of P/Q- and N-type VDCCs. However, the transcription level of laminin β2 did not decrease in double knock-out mice, suggesting that the synaptic accumulation of laminin β2 protein required its interaction with presynaptic VDCCs. These results suggest that presynaptic VDCCs link the target-derived synapse organizer laminin β2 to active-zone proteins and function as scaffolding proteins to anchor active-zone proteins to the presynaptic membrane.

    Funded by: NCRR NIH HHS: P20 RR016475, P20 RR024214, P20RR016475, P20RR024214; NICHD NIH HHS: P30 HD 002528, P30 HD002528

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2011;31;2;512-25

  • Bassoon and the synaptic ribbon organize Ca²+ channels and vesicles to add release sites and promote refilling.

    Frank T, Rutherford MA, Strenzke N, Neef A, Pangršič T, Khimich D, Fejtova A, Fetjova A, Gundelfinger ED, Liberman MC, Harke B, Bryan KE, Lee A, Egner A, Riedel D and Moser T

    InnerEarLab, Department of Otolaryngology and Center for Molecular Physiology of the Brain, University of Göttingen Medical Center, 37099 Göttingen, Germany.

    At the presynaptic active zone, Ca²+ influx triggers fusion of synaptic vesicles. It is not well understood how Ca²+ channel clustering and synaptic vesicle docking are organized. Here, we studied structure and function of hair cell ribbon synapses following genetic disruption of the presynaptic scaffold protein Bassoon. Mutant synapses--mostly lacking the ribbon--showed a reduction in membrane-proximal vesicles, with ribbonless synapses affected more than ribbon-occupied synapses. Ca²+ channels were also fewer at mutant synapses and appeared in abnormally shaped clusters. Ribbon absence reduced Ca²+ channel numbers at mutant and wild-type synapses. Fast and sustained exocytosis was reduced, notwithstanding normal coupling of the remaining Ca²+ channels to exocytosis. In vitro recordings revealed a slight impairment of vesicle replenishment. Mechanistic modeling of the in vivo data independently supported morphological and functional in vitro findings. We conclude that Bassoon and the ribbon (1) create a large number of release sites by organizing Ca²+ channels and vesicles, and (2) promote vesicle replenishment.

    Funded by: NHLBI NIH HHS: HL087120, R01 HL087120, R01 HL087120-03; NIAID NIH HHS: T32 AI007260, T32 AI007260-20, T32 AI07260; NIDCD NIH HHS: DC009433, P30 DC005209, P30 DC010362, R01 DC009433, R01 DC009433-04, R55 DC009433

    Neuron 2010;68;4;724-38

  • Bassoon speeds vesicle reloading at a central excitatory synapse.

    Hallermann S, Fejtova A, Schmidt H, Weyhersmüller A, Silver RA, Gundelfinger ED and Eilers J

    Carl Ludwig Institute of Physiology, Medical Faculty, University of Leipzig, Liebigstrasse 27, 04103 Leipzig, Germany. hallermann@medizin.uni-leipzig.de

    Sustained rate-coded signals encode many types of sensory modalities. Some sensory synapses possess specialized ribbon structures, which tether vesicles, to enable high-frequency signaling. However, central synapses lack these structures, yet some can maintain signaling over a wide bandwidth. To analyze the underlying molecular mechanisms, we investigated the function of the active zone core component Bassoon in cerebellar mossy fiber to granule cell synapses. We show that short-term synaptic depression is enhanced in Bassoon knockout mice during sustained high-frequency trains but basal synaptic transmission is unaffected. Fluctuation and quantal analysis as well as quantification with constrained short-term plasticity models revealed that the vesicle reloading rate was halved in the absence of Bassoon. Thus, our data show that the cytomatrix protein Bassoon speeds the reloading of vesicles to release sites at a central excitatory synapse.

    Funded by: Wellcome Trust

    Neuron 2010;68;4;710-23

  • Maturation of the olfactory sensory neurons by Apaf-1/caspase-9-mediated caspase activity.

    Ohsawa S, Hamada S, Kuida K, Yoshida H, Igaki T and Miura M

    Department of Genetics, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033, Japan.

    Although the apoptotic role of caspases has been largely understood, accumulating evidence in Drosophila suggests that caspases also control other processes than apoptotic cell death. However, how caspases contribute to the development of the mammalian nervous system remains obscure. Here, we provide unique evidence that Apaf-1/caspase-9-mediated caspase signaling regulates the development of olfactory sensory neurons (OSNs), which includes axonal projection, synapse formation, and maturation of these neurons. This caspase signaling leads to a cleavage of Semaphorin 7A, a membrane-anchored semaphorin that is required for the proper axonal projection. Mutant mice deficient for apaf-1 or caspase-9 exhibit misrouted axons, impaired synaptic formation, and defects in the maturation of OSNs without affecting the number of these cells. Our findings suggest that Apaf-1/caspase-9-mediated nonapoptotic caspase signaling is required for the proper neural network formation during olfactory development.

    Proceedings of the National Academy of Sciences of the United States of America 2010;107;30;13366-71

  • Impaired development of hippocampal mossy fibre synapses in mouse mutants for the presynaptic scaffold protein Bassoon.

    Lanore F, Blanchet C, Fejtova A, Pinheiro P, Richter K, Balschun D, Gundelfinger E and Mulle C

    Laboratoire Physiologie Cellulaire de la Synapse, CNRS UMR 5091, University of Bordeaux, Bordeaux, France.

    Bassoon, a protein highly concentrated at the synaptic active zone, is thought to participate in the organization of the cytomatrix at the site of neurotransmitter release. Bassoon is amongst the first proteins to accumulate at newly formed synaptic junctions, raising the question of the functional role of this protein in the early stages of synaptic development. Here we show that the course of synaptic maturation of hippocampal mossy fibre (MF) synapses (glutamatergic synapses with multiple release sites) is markedly altered during the first 2 weeks of postnatal development in mutant mice lacking the central region of Bassoon (Bsn(-/-) mice). At postnatal day 7 (P7), Bsn(-/-) mice display large amplitude MF-EPSCs with decreased paired pulse ratios, an abnormality which may be linked to deficits in the organization of the presynaptic active zone. Surprisingly, 1 week later, decreased MF-EPSCs amplitude is observed in Bsn(-/-) mice, consistent with the inactivation of a subset of synaptic release sites. Finally, at more mature states a decreased posttetanic potentiation is observed at MF-synapses. These results support the notion that Bassoon is important for organizing the presynaptic active zone during the postnatal maturation of glutamatergic synapses.

    The Journal of physiology 2010;588;Pt 12;2133-45

  • Onset coding is degraded in auditory nerve fibers from mutant mice lacking synaptic ribbons.

    Buran BN, Strenzke N, Neef A, Gundelfinger ED, Moser T and Liberman MC

    Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, USA. bburan@alum.mit.edu

    Synaptic ribbons, found at the presynaptic membrane of sensory cells in both ear and eye, have been implicated in the vesicle-pool dynamics of synaptic transmission. To elucidate ribbon function, we characterized the response properties of single auditory nerve fibers in mice lacking Bassoon, a scaffolding protein involved in anchoring ribbons to the membrane. In bassoon mutants, immunohistochemistry showed that fewer than 3% of the hair cells' afferent synapses retained anchored ribbons. Auditory nerve fibers from mutants had normal threshold, dynamic range, and postonset adaptation in response to tone bursts, and they were able to phase lock with normal precision to amplitude-modulated tones. However, spontaneous and sound-evoked discharge rates were reduced, and the reliability of spikes, particularly at stimulus onset, was significantly degraded as shown by an increased variance of first-spike latencies. Modeling based on in vitro studies of normal and mutant hair cells links these findings to reduced release rates at the synapse. The degradation of response reliability in these mutants suggests that the ribbon and/or Bassoon normally facilitate high rates of exocytosis and that its absence significantly compromises the temporal resolving power of the auditory system.

    Funded by: NIDCD NIH HHS: P30 DC005209, P30 DC005209-01, P30 DC05209, R01 DC000188, R01 DC000188-18, R01 DC00188

    The Journal of neuroscience : the official journal of the Society for Neuroscience 2010;30;22;7587-97

  • Absence of functional active zone protein Bassoon affects assembly and transport of ribbon precursors during early steps of photoreceptor synaptogenesis.

    Regus-Leidig H, tom Dieck S and Brandstätter JH

    Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, Staudtstr. 5, 91058 Erlangen, Germany.

    The retinal photoreceptor ribbon synapse is a structurally and functionally unique type of chemical synapse, specialized for tonic release of neurotransmitter in the dark. It is characterized by the presynaptic ribbon, an electron-dense organelle at the active zone, which is covered by hundreds of synaptic vesicles. Recently we showed that photoreceptor ribbon complexes are assembled from non-membranous, spherical densities--the precursor spheres--during the first two postnatal weeks of photoreceptor synaptogenesis. A core component of the precursor spheres and a key player in attaching the ribbon to the active zone is the presynaptic cytomatrix protein Bassoon. In this study, we examined in a comprehensive light and electron microscopic analysis whether Bassoon plays a role in the formation of the precursor spheres using Bassoon mutant mice lacking functional Bassoon. We report that developing Bassoon mutant photoreceptors contain fewer and smaller precursor spheres and that transport of precursor spheres to nascent synapses is delayed compared to wild-type controls. Moreover, western blot analyses of homogenates from postnatal day 0 (P0) to P14 Bassoon mutant retinae exhibit lower RIBEYE and Piccolo protein levels compared to the wild type, indicating elevated protein degradation in the absence of Bassoon. Our findings reveal a novel function of Bassoon in the early formation and delivery of precursor spheres to nascent ribbon synaptic sites in addition to its known role in ribbon anchoring during later stages of photoreceptor ribbon synaptogenesis.

    European journal of cell biology 2010;89;6;468-75

  • Piccolo and bassoon maintain synaptic vesicle clustering without directly participating in vesicle exocytosis.

    Mukherjee K, Yang X, Gerber SH, Kwon HB, Ho A, Castillo PE, Liu X and Südhof TC

    Department of Molecular and Cellular Physiology, Stanford University, CA 94304, USA.

    Piccolo and bassoon are highly homologous multidomain proteins of the presynaptic cytomatrix whose function is unclear. Here, we generated piccolo knockin/knockout mice that either contain wild-type levels of mutant piccolo unable to bind Ca(2+) (knockin), approximately 60% decreased levels of piccolo that is C-terminally truncated (partial knockout), or <5% levels of piccolo (knockout). All piccolo mutant mice were viable and fertile, but piccolo knockout mice exhibited increased postnatal mortality. Unexpectedly, electrophysiology and electron microscopy of piccolo-deficient synapses failed to uncover a major phenotype either in acute hippocampal slices or in cultured cortical neurons. To unmask potentially redundant functions of piccolo and bassoon, we thus acutely knocked down expression of bassoon in wild-type and piccolo knockout neurons. Despite a nearly complete loss of piccolo and bassoon, however, we still did not detect an electrophysiological phenotype in cultured piccolo- and bassoon-deficient neurons in either GABAergic or glutamatergic synaptic transmission. In contrast, electron microscopy revealed a significant reduction in synaptic vesicle clustering in double bassoon/piccolo-deficient synapses. Thus, we propose that piccolo and bassoon play a redundant role in synaptic vesicle clustering in nerve terminals without directly participating in neurotransmitter release.

    Funded by: Howard Hughes Medical Institute

    Proceedings of the National Academy of Sciences of the United States of America 2010;107;14;6504-9

  • Epilepsy-induced abnormal striatal plasticity in Bassoon mutant mice.

    Ghiglieri V, Picconi B, Sgobio C, Bagetta V, Barone I, Paillè V, Di Filippo M, Polli F, Gardoni F, Altrock W, Gundelfinger ED, De Sarro G, Bernardi G, Ammassari-Teule M, Di Luca M and Calabresi P

    Laboratorio di Neurofisiologia, Fondazione Santa Lucia, IRCCS c/o CERC, Rome, Italy.

    Recently, the striatum has been implicated in the spread of epileptic seizures. As the absence of functional scaffolding protein Bassoon in mutant mice is associated with the development of pronounced spontaneous seizures, we utilized this new genetic model of epilepsy to investigate seizure-induced changes in striatal synaptic plasticity. Mutant mice showed reduced long-term potentiation in striatal spiny neurons, associated with an altered N-methyl-D-aspartate (NMDA) receptor subunit distribution, whereas GABAergic fast-spiking (FS) interneurons showed NMDA-dependent short-term potentiation that was absent in wild-type animals. Alterations in the dendritic morphology of spiny neurons and in the number of FS interneurons were also observed. Early antiepileptic treatment with valproic acid reduced epileptic attacks and mortality, rescuing physiological striatal synaptic plasticity and NMDA receptor subunit composition. However, morphological alterations were not affected by antiepileptic treatment. Our results indicate that, in Bsn mutant mice, initial morphological alterations seem to reflect a more direct effect of the abnormal genotype, whereas plasticity changes are likely to be caused by the occurrence of repeated cortical seizures.

    The European journal of neuroscience 2009;29;10;1979-93

  • Effects of presynaptic mutations on a postsynaptic Cacna1s calcium channel colocalized with mGluR6 at mouse photoreceptor ribbon synapses.

    Specht D, Wu SB, Turner P, Dearden P, Koentgen F, Wolfrum U, Maw M, Brandstätter JH and tom Dieck S

    Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, Erlangen, Germany.

    Purpose: Photoreceptor ribbon synapses translate light-dependent changes of membrane potential into graded transmitter release via L-type voltage-dependent calcium channel (VDCC) activity. Functional abnormalities (e.g., a reduced electroretinogram b-wave), arising from mutations of presynaptic proteins, such as Bassoon and the VDCCalpha1 subunit Cacna1f, have been shown to altered transmitter release. L-type VDCCalpha1 subtype expression in wild-type and mutant mice was examined, to investigate the underlying pathologic mechanism.

    Methods: Two antisera against Cacna1f, and a Cacna1f mouse mutant (Cacna1fDeltaEx14-17) were generated. Immunocytochemistry for L-type VDCCalpha1 subunits and additional synaptic marker proteins was performed in wild-type, BassoonDeltaEx4-5 and Cacna1fDeltaEx14-17 mice.

    Results: Active zone staining at photoreceptor ribbon synapses with a panalpha1 antibody colocalized with staining for Cacna1f in wild-type mouse retina. Similarly, in the BassoonDeltaEx4-5 mouse, residual mislocalized staining for panalpha1 and Cacna1f showed colocalization. Unlike the presynaptic location of Cacna1f and panalpha1 antibody staining, the skeletal muscle VDCCalpha1 subunit Cacna1s was present postsynaptically at ON-bipolar cell dendrites, where it colocalized with metabotropic glutamate receptor 6 (mGluR6). Surprisingly, Cacna1s labeling was severely downregulated in the BassoonDeltaEx4-5 and Cacna1fDeltaEx14-17 mutants. Subsequent analyses revealed severely reduced ON-bipolar cell dendritic expression of the sarcoplasmic reticulum Ca(2+) ATPase Serca2 in both mouse mutants and of mGluR6 in the Cacna1fDeltaEx14-17 mutant.

    Conclusions: Presynaptic mutations leading to reduced photoreceptor-to-bipolar cell signaling are associated with disturbances in protein expression within postsynaptic dendrites. Moreover, detection of Cacna1s and Serca2 in ON-bipolar cell dendrites in wild-type animals suggests a putative role in regulation of postsynaptic Ca(2+) flux.

    Investigative ophthalmology & visual science 2009;50;2;505-15

  • The amino-terminal domain of glutamate receptor delta2 triggers presynaptic differentiation.

    Uemura T and Mishina M

    Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

    Glutamate receptor (GluR) delta2 selectively expressed in cerebellar Purkinje cells plays key roles in synapse formation, long-term depression and motor learning. We propose that GluRdelta2 regulates synapse formation by making a physical linkage between the active zone and postsynaptic density. To examine the issue, GluRdelta2-transfected 293T cells were cultured with cerebellar neurons. We found numerous punctate signals for presynaptic markers on the surface of 293T cells expressing GluRdelta2. The presynaptic specializations induced by GluRdelta2 were capable of exo- and endocytosis as indicated by FM1-43 dye labeling. Replacement of the extracellular N-terminal domain (NTD) of GluRdelta2 with that of the AMPA receptor GluRalpha1 abolished the inducing activity. The NTD of GluRdelta2 fused to the immunoglobulin constant region successfully induced the accumulation of presynaptic specializations on the surface of beads bearing the fusion protein. These results suggest that GluRdelta2 triggers presynaptic differentiation by direct interaction with presynaptic components through the NTD.

    Biochemical and biophysical research communications 2008;377;4;1315-9

  • A differential developmental pattern of spinal interneuron apoptosis during synaptogenesis: insights from genetic analyses of the protocadherin-gamma gene cluster.

    Prasad T, Wang X, Gray PA and Weiner JA

    Department of Biology, The University of Iowa, Iowa City, IA 52242, USA.

    Although the role of developmental apoptosis in shaping the complement and connectivity of sensory and motoneurons is well documented, the extent to which cell death affects the 13 cardinal classes of spinal interneurons is unclear. Using a series of genetic manipulations in vivo, we demonstrate for the first time a differential pattern of developmental apoptosis in molecularly identified spinal interneuron populations, and implicate the adhesion molecule family encoded by the 22-member protocadherin-gamma (Pcdh-gamma) gene cluster in its control. In constitutive Pcdh-gamma null mouse embryos, many interneuron populations undergo increased apoptosis, but to differing extents: for example, over 80% of En1-positive V1 neurons are lost, whereas only 30% of Chx10-positive V2a neurons are lost and there is no reduction in the number of V1-derived Renshaw cells. We show that this represents an exacerbation of a normal, underlying developmental pattern: the extent of each population's decrease in Pcdh-gamma mutants is precisely commensurate both with the extent of its loss during normal embryogenesis and with the extent of its increase in Bax(-/-) mice, in which apoptosis is genetically blocked. Interneuron apoptosis begins during the first wave of synaptogenesisis in the spinal cord, occurring first among ventral populations (primarily between E14 and E17), and only later among dorsal populations (primarily after P0). Utilizing a new, conditional Pcdh-gamma mutant allele, we show that the gamma-Pcdhs can promote survival non-cell-autonomously: mutant neurons can survive if they are surrounded by normal neurons, and normal neurons can undergo apoptosis if they are surrounded by mutant neurons.

    Funded by: NINDS NIH HHS: R01 NS055272, R01 NS055272-01A2

    Development (Cambridge, England) 2008;135;24;4153-64

  • The protein kinase DYRK1A regulates caspase-9-mediated apoptosis during retina development.

    Laguna A, Aranda S, Barallobre MJ, Barhoum R, Fernández E, Fotaki V, Delabar JM, de la Luna S, de la Villa P and Arbonés ML

    Center for Genomic Regulation, UPF, 08003 Barcelona, Spain.

    The precise regulation of programmed cell death is critical for the normal development of the nervous system. We show here that DYRK1A (minibrain), a protein kinase essential for normal growth, is a negative regulator of the intrinsic apoptotic pathway in the developing retina. We provide evidence that changes in Dyrk1A gene dosage in the mouse strongly alter the cellularity of inner retina layers and result in severe functional alterations. We show that DYRK1A does not affect the proliferation or specification of retina progenitor cells, but rather regulates the number of cells that die by apoptosis. We demonstrate that DYRK1A phosphorylates caspase-9 on threonine residue 125, and that this phosphorylation event is crucial to protect retina cells from apoptotic cell death. Our data suggest a model in which dysregulation of the apoptotic response in differentiating neurons participates in the neuropathology of diseases that display DYRK1A gene-dosage imbalance effects, such as Down's syndrome.

    Developmental cell 2008;15;6;841-53

  • Pikachurin, a dystroglycan ligand, is essential for photoreceptor ribbon synapse formation.

    Sato S, Omori Y, Katoh K, Kondo M, Kanagawa M, Miyata K, Funabiki K, Koyasu T, Kajimura N, Miyoshi T, Sawai H, Kobayashi K, Tani A, Toda T, Usukura J, Tano Y, Fujikado T and Furukawa T

    Department of Developmental Biology, Osaka Bioscience Institute, 6-2-4 Furuedai, Suita, Osaka, 565-0874, Japan.

    Exquisitely precise synapse formation is crucial for the mammalian CNS to function correctly. Retinal photoreceptors transfer information to bipolar and horizontal cells at a specialized synapse, the ribbon synapse. We identified pikachurin, an extracellular matrix-like retinal protein, and observed that it localized to the synaptic cleft in the photoreceptor ribbon synapse. Pikachurin null-mutant mice showed improper apposition of the bipolar cell dendritic tips to the photoreceptor ribbon synapses, resulting in alterations in synaptic signal transmission and visual function. Pikachurin colocalized with both dystrophin and dystroglycan at the ribbon synapses. Furthermore, we observed direct biochemical interactions between pikachurin and dystroglycan. Together, our results identify pikachurin as a dystroglycan-interacting protein and demonstrate that it has an essential role in the precise interactions between the photoreceptor ribbon synapse and the bipolar dendrites. This may also advance our understanding of the molecular mechanisms underlying the retinal electrophysiological abnormalities observed in muscular dystrophy patients.

    Nature neuroscience 2008;11;8;923-31

  • The protocadherin-alpha family is involved in axonal coalescence of olfactory sensory neurons into glomeruli of the olfactory bulb in mouse.

    Hasegawa S, Hamada S, Kumode Y, Esumi S, Katori S, Fukuda E, Uchiyama Y, Hirabayashi T, Mombaerts P and Yagi T

    KOKORO-Biology Group, Laboratories for Integrated Biology, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.

    Olfactory sensory neurons (OSNs) that express the same odorant receptor project their axons to specific glomeruli in the main olfactory bulb. Protocadherin-alpha (Pcdha) proteins, diverse cadherin-related molecules that are encoded as a gene cluster, are highly concentrated in OSN axons and olfactory glomeruli. Here, we describe Pcdha mutant mice, in which the constant region of the Pcdha gene cluster has been deleted by gene targeting. The mutant mice show abnormal sorting of OSN axons into glomeruli. There are multiple, small, extraneous glomeruli for the odorant receptors M71 and MOR23. These abnormal patterns of M71 and MOR23 glomeruli persist until adulthood. Many M71 glomeruli, but apparently not MOR23 glomeruli, are heterogeneous in axonal innervation. Thus, Pcdha molecules are involved in coalescence of OSN axons into OR-specific glomeruli of the olfactory bulb.

    Molecular and cellular neurosciences 2008;38;1;66-79

  • Morphological and metabolic changes in the cortex of mice lacking the functional presynaptic active zone protein bassoon: a combined 1H-NMR spectroscopy and histochemical study.

    Angenstein F, Hilfert L, Zuschratter W, Altrock WD, Niessen HG and Gundelfinger ED

    Special Laboratory for Non-Invasive Brain Imaging, Leibniz Institute for Neurobiology, Magdeburg, Germany. angenstein@ifn-magdeburg.de

    Mice lacking functional presynaptic active zone protein Bassoon are characterized by an enlarged cerebral cortex and an altered cortical activation pattern. This morphological and functional phenotype is associated with defined metabolic distortions as detected by a metabonomic approach using high-field (14.1 T) high-resolution 1H-nuclear magnetic resonance spectroscopy (MRS) in conjunction with statistical pattern recognition. Within the cortex but not in the cerebellum, concentrations of N-acetyl aspartate, glutamine, and glutamate are significantly reduced, whereas the majority of all other detectable low molecular metabolites are unchanged. The reduction of the neuron-specific metabolite N-acetyl aspartate in the cortex coincides with a significant decrease in neuronal density in cortical layer V. Comparing the neuron with glia cell densities across the cortex reveals cortex layer-dependent alterations in the ratio between both cell types. Whereas the ratio shifts significantly toward neurons in the cortical input layers IV, the ratio is reversed in cortical layer V. Consequently, the previously observed altered neuronal activation pattern in the cortex is reflected not only in defined cytoarchitectural anomalies but also in metabolic disturbances in the glutamine-glutamate and N-acetyl aspartate metabolism.

    Cerebral cortex (New York, N.Y. : 1991) 2008;18;4;890-7

  • Type 4 OFF cone bipolar cells of the mouse retina express calsenilin and contact cones as well as rods.

    Haverkamp S, Specht D, Majumdar S, Zaidi NF, Brandstätter JH, Wasco W, Wässle H and Tom Dieck S

    Department of Neuroanatomy, Max Planck Institute for Brain Research, 60528 Frankfurt/Main, Germany.

    Immunocytochemical discrimination of distinct bipolar cell types in the mouse retina is a prerequisite for analyzing retinal circuitry in wild-type and transgenic mice. Here we demonstrate that among the more than 10 anatomically defined mouse bipolar cell types, type 4 bipolar cells are specifically recognized by anti-calsenilin antibodies. Axon terminals in the inner plexiform layer are not readily identifiable because calsenilin is also expressed in a subset of amacrine and ganglion cells. In contrast, in the outer plexiform layer calsenilin immunoreactivity allows the analysis of photoreceptor to type 4 bipolar cell contacts. A dense plexus of calsenilin-positive dendrites makes several basal contacts at cone pedicles. An individual calsenilin-positive bipolar cell contacts five to seven cones. In addition, some calsenilin-positive dendrites contact rod photoreceptors. On average we counted 10 rod spherule contacts per type 4 bipolar cell, and approximately 10% of rods contacted type 4 bipolar cells. We suggest that type 4 bipolar cells, together with the recently described type 3a and b cells, provide an alternative and direct route from rods to OFF cone bipolar cells. In the Bassoon DeltaEx4/5 mouse, a mouse mutant that shows extensive remodeling of the rod system including sprouting of horizontal and rod bipolar cells into the outer nuclear layer due to impaired synaptic transmission, we found that in addition mixed-input (type 3 and 4) OFF bipolar cells sprout to ectopic sites. In contrast, true cone-selective type 1 and 2 OFF cone bipolar cells did not show sprouting in the Bassoon mouse mutant.

    Funded by: NIA NIH HHS: AG016361

    The Journal of comparative neurology 2008;507;1;1087-101

  • Structural and functional remodeling in the retina of a mouse with a photoreceptor synaptopathy: plasticity in the rod and degeneration in the cone system.

    Specht D, Tom Dieck S, Ammermüller J, Regus-Leidig H, Gundelfinger ED and Brandstätter JH

    Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, Staudtstrasse 5, 91058 Erlangen, Germany.

    Knowledge about the plastic and regenerative capacity of the retina is of key importance for therapeutic approaches to restore vision in patients who suffer from degenerative retinal diseases. In the retinae of mice, mutant for the presynaptic scaffolding protein Bassoon, signal transfer at photoreceptor ribbon synapses is disturbed due to impaired ribbon attachment to the active zone. In a long-term study we observed, with light and electron microscopic immunocytochemistry and electroretinographic recordings, two overlapping events in the Bassoon mutant retina, i.e. loss of photoreceptor synapses in the outer plexiform layer, and structural remodeling and formation of ectopic photoreceptor synapses in the outer nuclear layer, a region usually devoid of synapses. Formation of ectopic synaptic sites starts around the time when photoreceptor synaptogenesis is completed in wild-type mice and progresses throughout life. The result is a dense plexus of ectopic photoreceptor synapses with significantly altered but considerable synaptic transmission. Ectopic synapse formation is led by the sprouting of horizontal cells followed by the extension of rod bipolar cell neurites that fasciculate with and grow along the horizontal cell processes. Although only the rod photoreceptors and their postsynaptic partners show structural and functional remodeling, our study demonstrates the potential of the retina for long-lasting plastic changes.

    The European journal of neuroscience 2007;26;9;2506-15

  • EUCOMM--the European conditional mouse mutagenesis program.

    Friedel RH, Seisenberger C, Kaloff C and Wurst W

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

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

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

  • Qualitative and quantitative analyses of protein phosphorylation in naive and stimulated mouse synaptosomal preparations.

    Munton RP, Tweedie-Cullen R, Livingstone-Zatchej M, Weinandy F, Waidelich M, Longo D, Gehrig P, Potthast F, Rutishauser D, Gerrits B, Panse C, Schlapbach R and Mansuy IM

    Brain Research Institute, Medical Faculty of the University of Zürich, Switzerland.

    Activity-dependent protein phosphorylation is a highly dynamic yet tightly regulated process essential for cellular signaling. Although recognized as critical for neuronal functions, the extent and stoichiometry of phosphorylation in brain cells remain undetermined. In this study, we resolved activity-dependent changes in phosphorylation stoichiometry at specific sites in distinct subcellular compartments of brain cells. Following highly sensitive phosphopeptide enrichment using immobilized metal affinity chromatography and mass spectrometry, we isolated and identified 974 unique phosphorylation sites on 499 proteins, many of which are novel. To further explore the significance of specific phosphorylation sites, we used isobaric peptide labels and determined the absolute quantity of both phosphorylated and non-phosphorylated peptides of candidate phosphoproteins and estimated phosphorylation stoichiometry. The analyses of phosphorylation dynamics using differentially stimulated synaptic terminal preparations revealed activity-dependent changes in phosphorylation stoichiometry of target proteins. Using this method, we were able to differentiate between distinct isoforms of Ca2+/calmodulin-dependent protein kinase (CaMKII) and identify a novel activity-regulated phosphorylation site on the glutamate receptor subunit GluR1. Together these data illustrate that mass spectrometry-based methods can be used to determine activity-dependent changes in phosphorylation stoichiometry on candidate phosphopeptides following large scale phosphoproteome analysis of brain tissue.

    Molecular & cellular proteomics : MCP 2007;6;2;283-93

  • Manganese-enhanced MRI reveals structural and functional changes in the cortex of Bassoon mutant mice.

    Angenstein F, Niessen HG, Goldschmidt J, Lison H, Altrock WD, Gundelfinger ED and Scheich H

    Special Laboratory for Non-invasive Brain Imaging, Leibniz Institute for Neurobiology, Magdeburg, Germany. angenstein@ifn.magdeburg.de

    Manganese-enhanced magnetic resonance imaging (ME-MRI) was used to analyze the brain architecture in mice lacking the functional presynaptic active zone protein Bassoon. Anatomical characterization revealed a significant increase in the total brain volume in Bassoon mutants as compared with wild-type mice, which is mainly caused by changes in cortex and hippocampus volume. The measured enlargement in cortical volume coincides with an altered Mn2+ distribution within cortical layers as visualized by T1-weighted magnetic resonance imaging. Two days after manganese application, the cortex of Bassoon mutant mice appeared more laminated in ME-MRI, with an enhanced accumulation of manganese in deep, central, and superficial cortical cell layers. Whereas morphologically the cortical lamination is not affected by the absence of a functional Bassoon, an altered basal activation pattern was found in the cortex of the mutant mice both by metabolic labeling with [14C]-2-deoxyglucose and histochemical detection of the potassium analogue thallium uptake. Consequently, the results indicate that the absence of the functional presynaptic protein Bassoon causes disturbance in the formation of normal basal cortical activation patterns and thereby in the functional cortical architecture. Furthermore, this study shows that ME-MRI can become a valuable tool for a structural characterization of genetically modified mice.

    Cerebral cortex (New York, N.Y. : 1991) 2007;17;1;28-36

  • Compensation by tumor suppressor genes during retinal development in mice and humans.

    Donovan SL, Schweers B, Martins R, Johnson D and Dyer MA

    Department of Developmental Neurobiology, St, Jude Children's Research Hospital, Memphis, TN 38105, USA. stacy.donovan@stjude.org

    Background: The RB1 gene was the first tumor suppressor gene cloned from humans by studying genetic lesions in families with retinoblastoma. Children who inherit one defective copy of the RB1 gene have an increased susceptibility to retinoblastoma. Several years after the identification of the human RB1 gene, a targeted deletion of Rb was generated in mice. Mice with one defective copy of the Rb gene do not develop retinoblastoma. In this manuscript, we explore the different roles of the Rb family in human and mouse retinal development in order to better understand the species-specific difference in retinoblastoma susceptibility.

    Results: We found that the Rb family of proteins (Rb, p107 and p130) are expressed in a dynamic manner during mouse retinal development. The primary Rb family member expressed in proliferating embryonic retinal progenitor cells in mice is p107, which is required for appropriate cell cycle exit during retinogenesis. The primary Rb family member expressed in proliferating postnatal retinal progenitor cells is Rb. p130 protein is expressed redundantly with Rb in postmitotic cells of the inner nuclear layer and the ganglion cell layer of the mouse retina. When Rb is inactivated in an acute or chronic manner during mouse retinal development, p107 is upregulated in a compensatory manner. Similarly, when p107 is inactivated in the mouse retina, Rb is upregulated. No changes in p130 expression were seen when p107, Rb or both were inactivated in the developing mouse retina. In the human retina, RB1 was the primary family member expressed throughout development. There was very little if any p107 expressed in the developing human retina. In contrast to the developing mouse retina, when RB1 was acutely inactivated in the developing human fetal retina, p107 was not upregulated in a compensatory manner.

    Conclusion: We propose that intrinsic genetic compensation between Rb and p107 prevents retinoblastoma in Rb- or p107-deficient mice, but this compensation does not occur in humans. Together, these data suggest a model that explains why humans are susceptible to retinoblastoma following RB1 loss, but mice require both Rb and p107 gene inactivation.

    BMC biology 2006;4;14

  • Comprehensive identification of phosphorylation sites in postsynaptic density preparations.

    Trinidad JC, Specht CG, Thalhammer A, Schoepfer R and Burlingame AL

    Mass Spectrometry Facility, Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143, USA.

    In the mammalian central nervous system, the structure known as the postsynaptic density (PSD) is a dense complex of proteins whose function is to detect and respond to neurotransmitter released from presynaptic axon terminals. Regulation of protein phosphorylation in this molecular machinery is critical to the activity of its components, which include neurotransmitter receptors, kinases/phosphatases, scaffolding molecules, and proteins regulating cytoskeletal structure. To characterize the phosphorylation state of proteins in PSD samples, we combined strong cation exchange (SCX) chromatography with IMAC. Initially, tryptic peptides were separated by cation exchange and analyzed by reverse phase chromatography coupled to tandem mass spectrometry, which led to the identification of phosphopeptides in most SCX fractions. Because each of these individual fractions was too complex to characterize completely in single LC-MS/MS runs, we enriched for phosphopeptides by performing IMAC on each SCX fraction, yielding at least a 3-fold increase in identified phosphopeptides relative to either approach alone (SCX or IMAC). This enabled us to identify at least one site of phosphorylation on 23% (287 of 1,264) of all proteins found to be present in the postsynaptic density preparation. In total, we identified 998 unique phosphorylated peptides, mapping to 723 unique sites of phosphorylation. At least one exact site of phosphorylation was determined on 62% (621 of 998) of all phosphopeptides, and approximately 80% of identified phosphorylation sites are novel.

    Funded by: NCRR NIH HHS: RR14606; Wellcome Trust

    Molecular & cellular proteomics : MCP 2006;5;5;914-22

  • O-linked N-acetylglucosamine proteomics of postsynaptic density preparations using lectin weak affinity chromatography and mass spectrometry.

    Vosseller K, Trinidad JC, Chalkley RJ, Specht CG, Thalhammer A, Lynn AJ, Snedecor JO, Guan S, Medzihradszky KF, Maltby DA, Schoepfer R and Burlingame AL

    Mass Spectrometry Facility, Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143, USA. kav27@drexel.edu

    O-GlcNAc is a widespread dynamic carbohydrate modification of cytosolic and nuclear proteins with features analogous to phosphorylation. O-GlcNAc acts critically in many cellular processes, including signal transduction, protein degradation, and regulation of gene expression. However, the study of its specific regulatory functions has been limited by difficulties in mapping sites of O-GlcNAc modification. We report methods for direct enrichment and identification of in vivo O-GlcNAc-modified peptides through lectin weak affinity chromatography (LWAC) and mass spectrometry. The effectiveness of this strategy on complex peptide mixtures was demonstrated through enrichment of 145 unique O-GlcNAc-modified peptides from a postsynaptic density preparation. 65 of these O-GlcNAc-modified peptides were sequenced and belonged to proteins with diverse functions in synaptic transmission. Beta-elimination/Michael addition, MS(3) on O-GlcNAc neutral loss ions, and electron capture dissociation were shown to facilitate analysis of O-GlcNAc-modified peptides/sites from lectin weak affinity chromatography enriched postsynaptic density samples. Bassoon and Piccolo, proteins critical to synapse assembly and vesicle docking, were extensively modified by O-GlcNAc. In some cases, O-GlcNAc was mapped to peptides previously identified as phosphorylated, indicating potential interplay between these modifications. Shared substrate amino acid context was apparent in subsets of O-GlcNAc-modified peptides, including "PVST" and a novel "TTA" motif (two hydroxyl-containing amino acids adjacent to an alanine). The results suggest specific roles for O-GlcNAc modification in synaptic transmission, establish a basis for site-specific regulatory studies, and provide methods that will facilitate O-GlcNAc proteome analysis across a wide variety of cells and tissues.

    Funded by: NCRR NIH HHS: RR14606; Wellcome Trust

    Molecular & cellular proteomics : MCP 2006;5;5;923-34

  • BGEM: an in situ hybridization database of gene expression in the embryonic and adult mouse nervous system.

    Magdaleno S, Jensen P, Brumwell CL, Seal A, Lehman K, Asbury A, Cheung T, Cornelius T, Batten DM, Eden C, Norland SM, Rice DS, Dosooye N, Shakya S, Mehta P and Curran T

    Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States.

    Funded by: NINDS NIH HHS: 5R37NS036558, N01-NS-0-2331, R37 NS036558

    PLoS biology 2006;4;4;e86

  • Munc18-1 stabilizes syntaxin 1, but is not essential for syntaxin 1 targeting and SNARE complex formation.

    Toonen RF, de Vries KJ, Zalm R, Südhof TC and Verhage M

    Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.

    Munc18-1, a member of the Sec1/Munc18 (SM) protein family, is essential for synaptic vesicle exocytosis. Munc18-1 binds tightly to the SNARE protein syntaxin 1, but the physiological significance and functional role of this interaction remain unclear. Here we show that syntaxin 1 levels are reduced by 70% in munc18-1 knockout mice. Pulse-chase analysis in transfected HEK293 cells revealed that Munc18-1 directly promotes the stability of syntaxin 1, consistent with a chaperone function. However, the residual syntaxin 1 in munc18-1 knockout mice is still correctly targeted to synapses and efficiently forms SDS-resistant SNARE complexes, demonstrating that Munc18-1 is not required for syntaxin 1 function as such. These data demonstrate that the Munc18-1 interaction with syntaxin 1 is physiologically important, but does not represent a classical chaperone-substrate relationship. Instead, the presence of SNARE complexes in the absence of membrane fusion in munc18-1 knockout mice indicates that Munc18-1 either controls the spatially correct assembly of core complexes for SNARE-dependent fusion, or acts as a direct component of the fusion machinery itself.

    Journal of neurochemistry 2005;93;6;1393-400

  • Structurally and functionally unique complexins at retinal ribbon synapses.

    Reim K, Wegmeyer H, Brandstätter JH, Xue M, Rosenmund C, Dresbach T, Hofmann K and Brose N

    Department of Molecular Neurobiology, Max-Planck-Institute for Experimental Medicine, D-37075 Göttingen, Germany.

    Ribbon synapses in retinal sensory neurons maintain large pools of readily releasable synaptic vesicles. This allows them to release several hundreds of vesicles per second at every presynaptic release site. The molecular components that cause this high transmitter release efficiency of ribbon synapses are unknown. In the present study, we identified and characterized two novel vertebrate complexins (CPXs), CPXs III and IV, that are the only CPX isoforms present in retinal ribbon synapses. CPXs III and IV are COOH-terminally farnesylated, and, like CPXs I and II, bind to SNAP receptor complexes. CPXs III and IV can functionally replace CPXs I and II, and their COOH-terminal farnesylation regulates their synaptic targeting and modulatory function in transmitter release. The novel CPXs III and IV may contribute to the unique release efficacy of retinal sensory neurons.

    The Journal of cell biology 2005;169;4;669-80

  • Hair cell synaptic ribbons are essential for synchronous auditory signalling.

    Khimich D, Nouvian R, Pujol R, Tom Dieck S, Egner A, Gundelfinger ED and Moser T

    Department of Otolaryngology and Center for Molecular Physiology of the Brain, University of Goettingen, 37099 Goettingen, Germany.

    Hearing relies on faithful synaptic transmission at the ribbon synapse of cochlear inner hair cells (IHCs). At present, the function of presynaptic ribbons at these synapses is still largely unknown. Here we show that anchoring of IHC ribbons is impaired in mouse mutants for the presynaptic scaffolding protein Bassoon. The lack of active-zone-anchored synaptic ribbons reduced the presynaptic readily releasable vesicle pool, and impaired synchronous auditory signalling as revealed by recordings of exocytic IHC capacitance changes and sound-evoked activation of spiral ganglion neurons. Both exocytosis of the hair cell releasable vesicle pool and the number of synchronously activated spiral ganglion neurons co-varied with the number of anchored ribbons during development. Interestingly, ribbon-deficient IHCs were still capable of sustained exocytosis with normal Ca2+-dependence. Endocytic membrane retrieval was intact, but an accumulation of tubular and cisternal membrane profiles was observed in ribbon-deficient IHCs. We conclude that ribbon-dependent synchronous release of multiple vesicles at the hair cell afferent synapse is essential for normal hearing.

    Nature 2005;434;7035;889-94

  • Molecular dissection of the photoreceptor ribbon synapse: physical interaction of Bassoon and RIBEYE is essential for the assembly of the ribbon complex.

    tom Dieck S, Altrock WD, Kessels MM, Qualmann B, Regus H, Brauner D, Fejtová A, Bracko O, Gundelfinger ED and Brandstätter JH

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

    The ribbon complex of retinal photoreceptor synapses represents a specialization of the cytomatrix at the active zone (CAZ) present at conventional synapses. In mice deficient for the CAZ protein Bassoon, ribbons are not anchored to the presynaptic membrane but float freely in the cytoplasm. Exploiting this phenotype, we dissected the molecular structure of the photoreceptor ribbon complex. Identifiable CAZ proteins segregate into two compartments at the ribbon: a ribbon-associated compartment including Piccolo, RIBEYE, CtBP1/BARS, RIM1, and the motor protein KIF3A, and an active zone compartment including RIM2, Munc13-1, a Ca2+ channel alpha1 subunit, and ERC2/CAST1. A direct interaction between the ribbon-specific protein RIBEYE and Bassoon seems to link the two compartments and is responsible for the physical integrity of the photoreceptor ribbon complex. Finally, we found the RIBEYE homologue CtBP1 at ribbon and conventional synapses, suggesting a novel role for the CtBP/BARS family in the molecular assembly and function of central nervous system synapses.

    The Journal of cell biology 2005;168;5;825-36

  • Proteomic analysis of in vivo phosphorylated synaptic proteins.

    Collins MO, Yu L, Coba MP, Husi H, Campuzano I, Blackstock WP, Choudhary JS and Grant SG

    Division of Neuroscience, University of Edinburgh, Edinburgh EH8 9JZ, UK.

    In the nervous system, protein phosphorylation is an essential feature of synaptic function. Although protein phosphorylation is known to be important for many synaptic processes and in disease, little is known about global phosphorylation of synaptic proteins. Heterogeneity and low abundance make protein phosphorylation analysis difficult, particularly for mammalian tissue samples. Using a new approach, combining both protein and peptide immobilized metal affinity chromatography and mass spectrometry data acquisition strategies, we have produced the first large scale map of the mouse synapse phosphoproteome. We report over 650 phosphorylation events corresponding to 331 sites (289 have been unambiguously assigned), 92% of which are novel. These represent 79 proteins, half of which are novel phosphoproteins, and include several highly phosphorylated proteins such as MAP1B (33 sites) and Bassoon (30 sites). An additional 149 candidate phosphoproteins were identified by profiling the composition of the protein immobilized metal affinity chromatography enrichment. All major synaptic protein classes were observed, including components of important pre- and postsynaptic complexes as well as low abundance signaling proteins. Bioinformatic and in vitro phosphorylation assays of peptide arrays suggest that a small number of kinases phosphorylate many proteins and that each substrate is phosphorylated by many kinases. These data substantially increase existing knowledge of synapse protein phosphorylation and support a model where the synapse phosphoproteome is functionally organized into a highly interconnected signaling network.

    The Journal of biological chemistry 2005;280;7;5972-82

  • Genomic analysis of mouse retinal development.

    Blackshaw S, Harpavat S, Trimarchi J, Cai L, Huang H, Kuo WP, Weber G, Lee K, Fraioli RE, Cho SH, Yung R, Asch E, Ohno-Machado L, Wong WH and Cepko CL

    Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, USA.

    The vertebrate retina is comprised of seven major cell types that are generated in overlapping but well-defined intervals. To identify genes that might regulate retinal development, gene expression in the developing retina was profiled at multiple time points using serial analysis of gene expression (SAGE). The expression patterns of 1,051 genes that showed developmentally dynamic expression by SAGE were investigated using in situ hybridization. A molecular atlas of gene expression in the developing and mature retina was thereby constructed, along with a taxonomic classification of developmental gene expression patterns. Genes were identified that label both temporal and spatial subsets of mitotic progenitor cells. For each developing and mature major retinal cell type, genes selectively expressed in that cell type were identified. The gene expression profiles of retinal Müller glia and mitotic progenitor cells were found to be highly similar, suggesting that Müller glia might serve to produce multiple retinal cell types under the right conditions. In addition, multiple transcripts that were evolutionarily conserved that did not appear to encode open reading frames of more than 100 amino acids in length ("noncoding RNAs") were found to be dynamically and specifically expressed in developing and mature retinal cell types. Finally, many photoreceptor-enriched genes that mapped to chromosomal intervals containing retinal disease genes were identified. These data serve as a starting point for functional investigations of the roles of these genes in retinal development and physiology.

    Funded by: NCI NIH HHS: P20 CA096470, P20 CA96470; NEI NIH HHS: EY08064, R01 EY008064

    PLoS biology 2004;2;9;E247

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

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

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

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

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

  • Role of beta-catenin in synaptic vesicle localization and presynaptic assembly.

    Bamji SX, Shimazu K, Kimes N, Huelsken J, Birchmeier W, Lu B and Reichardt LF

    Howard Hughes Medical Institute and Department of Physiology, University of California, San Francisco, San Francisco, CA 94143, USA.

    Cadherins and catenins are thought to promote adhesion between pre and postsynaptic elements in the brain. Here we show a role for beta-catenin in localizing the reserved pool of vesicles at presynaptic sites. Deletion of beta-catenin in hippocampal pyramidal neurons in vivo resulted in a reduction in the number of reserved pool vesicles per synapse and an impaired response to prolonged repetitive stimulation. This corresponded to a dispersion of vesicles along the axon in cultured neurons. Interestingly, these effects are not due to beta-catenin's involvement in cadherin-mediated adhesion or wnt signaling. Instead, beta-catenin modulates vesicle localization via its PDZ binding domain to recruit PDZ proteins such as Veli to cadherin at synapses. This study defines a specific role for cadherins and catenins in synapse organization beyond their roles in mediating cell adhesion.

    Funded by: NINDS NIH HHS: P01 NS016033, P01 NS016033-21

    Neuron 2003;40;4;719-31

  • Prediction of the coding sequences of mouse homologues of KIAA gene: III. the complete nucleotide sequences of 500 mouse KIAA-homologous cDNAs identified by screening of terminal sequences of cDNA clones randomly sampled from size-fractionated libraries.

    Okazaki N, Kikuno R, Ohara R, Inamoto S, Koseki H, Hiraoka S, Saga Y, Nagase T, Ohara O and Koga H

    Kazusa DNA Research Institute, 2-6-7 Kazusa-kamatari, Kisarazu, Chiba 292-0818, Japan.

    We have conducted a human cDNA project to predict protein-coding sequences (CDSs) in large cDNAs (> 4 kb) since 1994, and the number of newly identified genes, known as KIAA genes, already exceeds 2000. The ultimate goal of this project is to clarify the physiological functions of the proteins encoded by KIAA genes. To this end, the project has recently been expanded to include isolation and characterization of mouse KIAA-counterpart genes. We herein present the entire sequences and the chromosome loci of 500 mKIAA cDNA clones and 13 novel cDNA clones that were incidentally identified during this project. The average size of the 513 cDNA sequences reached 4.3 kb and that of the deduced amino acid sequences from these cDNAs was 816 amino acid residues. By comparison of the predicted CDSs between mouse and human KIAAs, 12 mKIAA cDNA clones were assumed to be differently spliced isoforms of the human cDNA clones. The comparison of mouse and human sequences also revealed that four pairs of human KIAA cDNAs are derived from single genes. Notably, a homology search against the public database indicated that 4 out of 13 novel cDNA clones were homologous to the disease-related genes.

    DNA research : an international journal for rapid publication of reports on genes and genomes 2003;10;4;167-80

  • The presynaptic active zone protein bassoon is essential for photoreceptor ribbon synapse formation in the retina.

    Dick O, tom Dieck S, Altrock WD, Ammermüller J, Weiler R, Garner CC, Gundelfinger ED and Brandstätter JH

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

    The photoreceptor ribbon synapse is a highly specialized glutamatergic synapse designed for the continuous flow of synaptic vesicles to the neurotransmitter release site. The molecular mechanisms underlying ribbon synapse formation are poorly understood. We have investigated the role of the presynaptic cytomatrix protein Bassoon, a major component of the photoreceptor ribbon, in a mouse retina deficient of functional Bassoon protein. Photoreceptor ribbons lacking Bassoon are not anchored to the presynaptic active zones. This results in an impaired photoreceptor synaptic transmission, an abnormal dendritic branching of neurons postsynaptic to photoreceptors, and the formation of ectopic synapses. These findings suggest a critical role of Bassoon in the formation and the function of photoreceptor ribbon synapses of the mammalian retina.

    Funded by: NIA NIH HHS: P01 AG06569; NICHD NIH HHS: P50 HD32901; NINDS NIH HHS: R01 NS39471

    Neuron 2003;37;5;775-86

  • Functional inactivation of a fraction of excitatory synapses in mice deficient for the active zone protein bassoon.

    Altrock WD, tom Dieck S, Sokolov M, Meyer AC, Sigler A, Brakebusch C, Fässler R, Richter K, Boeckers TM, Potschka H, Brandt C, Löscher W, Grimberg D, Dresbach T, Hempelmann A, Hassan H, Balschun D, Frey JU, Brandstätter JH, Garner CC, Rosenmund C and Gundelfinger ED

    Leibniz Institute for Neurobiology, 39118 Magdeburg, Germany.

    Mutant mice lacking the central region of the presynaptic active zone protein Bassoon were generated to establish the role of this protein in the assembly and function of active zones as sites of synaptic vesicle docking and fusion. Our data show that the loss of Bassoon causes a reduction in normal synaptic transmission, which can be attributed to the inactivation of a significant fraction of glutamatergic synapses. At these synapses, vesicles are clustered and docked in normal numbers but are unable to fuse. Phenotypically, the loss of Bassoon causes spontaneous epileptic seizures. These data show that Bassoon is not essential for synapse formation but plays an essential role in the regulated neurotransmitter release from a subset of glutamatergic synapses.

    Funded by: NIA NIH HHS: P01 AG06569; NICHD NIH HHS: P50 HD32901; NINDS NIH HHS: R01 NS39471

    Neuron 2003;37;5;787-800

  • Cellular localization of the vesicular inhibitory amino acid transporter in the mouse and human retina.

    Jellali A, Stussi-Garaud C, Gasnier B, Rendon A, Sahel JA, Dreyfus H and Picaud S

    Laboratoire de Physiopathologie Cellulaire et Moléculaire de la Rétine, INSERM EMI-99-18, Université Louis Pasteur, 1 Place de l'Hôpital, 67091 Strasbourg Cedex, France.

    Horizontal cells are classically thought to mediate lateral inhibition by gamma-aminobutyric acid (GABA)-transporter mediated release. In the mammalian retina, however, GABA uptake and cloned GABA transporter were not detected in horizontal cells. Furthermore, the vesicular inhibitory amino acid transporter (VIAAT or VGAT) that loads GABA and glycine into synaptic vesicles was reported recently to be expressed in horizontal cells. To further assess synaptic transmission in mammalian horizontal cells, we examined the subcellular distribution of VIAAT in mouse and human retina by confocal microscopy with specific cell markers. VIAAT was observed in the mouse outer plexiform layer as punctate structures that localized in calbindin-positive horizontal cells. These structures were in close apposition with synaptophysin-, PSD-95-, dystrophin-, and bassoon-immunopositive photoreceptor terminals, suggesting that VIAAT is localized in horizontal cell tips at photoreceptor terminals. VIAAT-positive puncta were also in apposition to lectin-labeled cone terminals or dendrites of PKCalpha-immunopositive rod bipolar cells, indicating that VIAAT is expressed in horizontal cell tips at both rod and cone terminals. By contrast, only a very few puncta were observed in the human outer plexiform layer, whereas the inner plexiform layer remained labeled as in the mouse retina. When using adult human retinal cells in culture, horizontal cells identified by parvalbumin immunostaining were found to contain VIAAT, either at their terminals or throughout the entire cell similarly as in syntaxin-immunopositive cells. These differences between human retinal tissue and cultured cells were attributed to VIAAT degradation in postmortem retinal tissue. VIAAT localization in mouse and human horizontal cells further support the role of inhibitory transmitters in lateral inhibition at the photoreceptor terminals.

    The Journal of comparative neurology 2002;449;1;76-87

  • The gamma-aminobutyric acid type A receptor (GABAAR)-associated protein GABARAP interacts with gephyrin but is not involved in receptor anchoring at the synapse.

    Kneussel M, Haverkamp S, Fuhrmann JC, Wang H, Wässle H, Olsen RW and Betz H

    Departments of Neurochemistry and Neuroanatomy, Max Planck Institute for Brain Research, Deutschordenstrasse 46, D-60528 Frankfurt/Main, Germany.

    gamma-Aminobutyric acid type A receptors (GABA(A)Rs) are ligand-gated chloride channels that exist in numerous distinct subunit combinations. At postsynaptic membrane specializations, different GABA(A)R isoforms colocalize with the tubulin-binding protein gephyrin. However, direct interactions of GABA(A)R subunits with gephyrin have not been reported. Recently, the GABA(A)R-associated protein GABARAP was found to bind to the gamma2 subunit of GABA(A)Rs. Here we show that GABARAP interacts with gephyrin in both biochemical assays and transfected cells. Confocal analysis of neurons derived from wild-type and gephyrin-knockout mice revealed that GABARAP is highly enriched in intracellular compartments, but not at gephyrin-positive postsynaptic membrane specializations. Our data indicate that GABARAP-gephyrin interactions are not important for postsynaptic GABA(A)R anchoring but may be implicated in receptor sorting and/or targeting mechanisms. Consistent with this idea, a close homolog of GABARAP, p16, has been found to function as a late-acting intra-Golgi transport factor.

    Funded by: NINDS NIH HHS: NS28772, R01 NS028772

    Proceedings of the National Academy of Sciences of the United States of America 2000;97;15;8594-9

  • Fv2 encodes a truncated form of the Stk receptor tyrosine kinase.

    Persons DA, Paulson RF, Loyd MR, Herley MT, Bodner SM, Bernstein A, Correll PH and Ney PA

    Department of Experimental Hematology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.

    The Friend virus susceptibility 2 (Fv2) locus encodes a dominant host factor that confers susceptibility to Friend virus-induced erythroleukaemia in mice. We mapped Fv2 to a 1.0-Mb interval that also contained the gene (Ron) encoding the stem cell kinase receptor (Stk). A truncated form of Stk (Sf-stk), which was the most abundant form of Stk in Fv2-sensitive (Fv2ss) erythroid cells, was not expressed in Fv2 resistant (Fv2rr) cells. Enforced expression of Sf-stk conferred susceptibility to Friend disease, whereas targeted disruption of Ron caused resistance. We conclude that the Fv2 locus encodes Ron, and that a naturally expressed, truncated form of Stk confers susceptibility to Friend virus-induced erythroleukaemia.

    Funded by: NCI NIH HHS: P30 CA21765, R01 CA084214, R01 CA084214-01, R01 CA084214-02, R01 CA084214-03, R01 CA084214-04, R01 CA084214-05

    Nature genetics 1999;23;2;159-65

  • Bassoon, a novel zinc-finger CAG/glutamine-repeat protein selectively localized at the active zone of presynaptic nerve terminals.

    tom Dieck S, Sanmartí-Vila L, Langnaese K, Richter K, Kindler S, Soyke A, Wex H, Smalla KH, Kämpf U, Fränzer JT, Stumm M, Garner CC and Gundelfinger ED

    Leibniz Institute for Neurobiology, D-39118 Magdeburg, Germany.

    The molecular architecture of the cytomatrix of presynaptic nerve terminals is poorly understood. Here we show that Bassoon, a novel protein of >400,000 Mr, is a new component of the presynaptic cytoskeleton. The murine bassoon gene maps to chromosome 9F. A comparison with the corresponding rat cDNA identified 10 exons within its protein-coding region. The Bassoon protein is predicted to contain two double-zinc fingers, several coiled-coil domains, and a stretch of polyglutamines (24 and 11 residues in rat and mouse, respectively). In some human proteins, e.g., Huntingtin, abnormal amplification of such poly-glutamine regions causes late-onset neurodegeneration. Bassoon is highly enriched in synaptic protein preparations. In cultured hippocampal neurons, Bassoon colocalizes with the synaptic vesicle protein synaptophysin and Piccolo, a presynaptic cytomatrix component. At the ultrastructural level, Bassoon is detected in axon terminals of hippocampal neurons where it is highly concentrated in the vicinity of the active zone. Immunogold labeling of synaptosomes revealed that Bassoon is associated with material interspersed between clear synaptic vesicles, and biochemical studies suggest a tight association with cytoskeletal structures. These data indicate that Bassoon is a strong candidate to be involved in cytomatrix organization at the site of neurotransmitter release.

    Funded by: NICHD NIH HHS: P50 HD32901

    The Journal of cell biology 1998;142;2;499-509

Gene lists (8)

Gene List Source Species Name Description Gene count
L00000001 G2C Mus musculus Mouse PSD Mouse PSD adapted from Collins et al (2006) 1080
L00000005 G2C Mus musculus Mouse mGluR5 Mouse mGluR5 complex adapted from Collins et al (2006) 52
L00000007 G2C Mus musculus Mouse NRC Mouse NRC adapted from Collins et al (2006) 186
L00000008 G2C Mus musculus Mouse PSP Mouse PSP adapted from Collins et al (2006) 1121
L00000060 G2C Mus musculus BAYES-COLLINS-HUMAN-PSD-CONSENSUS Human cortex PSD consensus (ortho) 748
L00000062 G2C Mus musculus BAYES-COLLINS-MOUSE-PSD-CONSENSUS Mouse cortex PSD consensus 984
L00000070 G2C Mus musculus BAYES-COLLINS-HUMAN-PSD-FULL Human cortex biopsy PSD full list (ortho) 1461
L00000072 G2C Mus musculus BAYES-COLLINS-MOUSE-PSD-FULL Mouse cortex PSD full list 1556
© G2C 2014. The Genes to Cognition Programme received funding from The Wellcome Trust and the EU FP7 Framework Programmes:
EUROSPIN (FP7-HEALTH-241498), SynSys (FP7-HEALTH-242167) and GENCODYS (FP7-HEALTH-241995).

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