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Barker E, Milburn AE, Helassa N, Hammond DE, Sanchez-Soriano N, Morgan A, Barclay JW. Proximity labelling reveals effects of disease-causing mutation on the DNAJC5/cysteine string protein α interactome. Biochem J 2024; 481:BCJ20230319. [PMID: 38193346 PMCID: PMC10903463 DOI: 10.1042/bcj20230319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 01/05/2024] [Accepted: 01/09/2024] [Indexed: 01/10/2024]
Abstract
Cysteine string protein α (CSPα), also known as DNAJC5, is a member of the DnaJ/Hsp40 family of co-chaperones. The name derives from a cysteine-rich domain, palmitoylation of which enables localization to intracellular membranes, notably neuronal synaptic vesicles. Mutations in the DNAJC5 gene that encodes CSPα cause autosomal dominant, adult-onset neuronal ceroid lipofuscinosis (ANCL), a rare neurodegenerative disease. As null mutations in CSP-encoding genes in flies, worms and mice similarly result in neurodegeneration, CSP is evidently an evolutionarily conserved neuroprotective protein. However, the client proteins that CSP chaperones to prevent neurodegeneration remain unclear. Traditional methods for identifying protein-protein interactions such as yeast 2-hybrid and affinity purification approaches are poorly suited to CSP, due to its requirement for membrane anchoring and its tendency to aggregate after cell lysis. Therefore, we employed proximity labelling, which enables identification of interacting proteins in situ in living cells via biotinylation. Neuroendocrine PC12 cell lines stably expressing wild type or L115R ANCL mutant CSP constructs fused to miniTurbo were generated; then the biotinylated proteomes were analysed by liquid chromatographymass spectrometry (LCMS) and validated by western blotting. This confirmed several known CSP-interacting proteins, such as Hsc70 and SNAP-25, but also revealed novel binding proteins, including STXBP1/Munc18-1. Interestingly, some protein interactions (such as Hsc70) were unaffected by the L115R mutation, whereas others (including SNAP-25 and STXBP1/Munc18-1) were inhibited. These results define the CSP interactome in a neuronal model cell line and reveal interactions that are affected by ANCL mutation and hence may contribute to the neurodegeneration seen in patients.
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Affiliation(s)
- Eleanor Barker
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Amy E. Milburn
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Nordine Helassa
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Dean E. Hammond
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Natalia Sanchez-Soriano
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Alan Morgan
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
| | - Jeff W. Barclay
- Department of Biochemistry, Cell and Systems Biology, ISMIB, University of Liverpool, Liverpool, U.K
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The bacterial toxin ExoU requires a host trafficking chaperone for transportation and to induce necrosis. Nat Commun 2021; 12:4024. [PMID: 34188051 PMCID: PMC8241856 DOI: 10.1038/s41467-021-24337-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 06/11/2021] [Indexed: 12/17/2022] Open
Abstract
Pseudomonas aeruginosa can cause nosocomial infections, especially in ventilated or cystic fibrosis patients. Highly pathogenic isolates express the phospholipase ExoU, an effector of the type III secretion system that acts on plasma membrane lipids, causing membrane rupture and host cell necrosis. Here, we use a genome-wide screen to discover that ExoU requires DNAJC5, a host chaperone, for its necrotic activity. DNAJC5 is known to participate in an unconventional secretory pathway for misfolded proteins involving anterograde vesicular trafficking. We show that DNAJC5-deficient human cells, or Drosophila flies knocked-down for the DNAJC5 orthologue, are largely resistant to ExoU-dependent virulence. ExoU colocalizes with DNAJC5-positive vesicles in the host cytoplasm. DNAJC5 mutations preventing vesicle trafficking (previously identified in adult neuronal ceroid lipofuscinosis, a human congenital disease) inhibit ExoU-dependent cell lysis. Our results suggest that, once injected into the host cytoplasm, ExoU docks to DNAJC5-positive secretory vesicles to reach the plasma membrane, where it can exert its phospholipase activity Phospholipase ExoU from Pseudomonas aeruginosa acts on plasma membrane lipids in infected cells, causing membrane rupture and host cell necrosis. Here, Deruelle et al. show that once injected into the host cytoplasm, ExoU requires a host chaperone found on secretory vesicles to reach the plasma membrane and exerts its phospholipase activity.
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Gundersen CB. Cysteine string proteins. Prog Neurobiol 2020; 188:101758. [DOI: 10.1016/j.pneurobio.2020.101758] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 01/06/2020] [Accepted: 01/13/2020] [Indexed: 12/17/2022]
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The Role of Cysteine String Protein α Phosphorylation at Serine 10 and 34 by Protein Kinase Cγ for Presynaptic Maintenance. J Neurosci 2017; 38:278-290. [PMID: 29167402 DOI: 10.1523/jneurosci.1649-17.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 10/23/2017] [Accepted: 11/12/2017] [Indexed: 01/05/2023] Open
Abstract
Protein kinase Cγ (PKCγ) knock-out (KO) animals exhibit symptoms of Parkinson's disease (PD), including dopaminergic neuronal loss in the substantia nigra. However, the PKCγ substrates responsible for the survival of dopaminergic neurons in vivo have not yet been elucidated. Previously, we found 10 potent substrates in the striatum of PKCγ-KO mice. Here, we focused on cysteine string protein α (CSPα), a protein from the heat shock protein (HSP) 40 cochaperone families localized on synaptic vesicles. We found that in cultured cells, PKCγ phosphorylates CSPα at serine (Ser) 10 and Ser34. Additionally, apoptosis was found to have been enhanced by the overexpression of a phosphorylation-null mutant of CSPα, CSPα(S10A/S34A). Compared with wild-type (WT) CSPα, the CSPα(S10A/S34A) mutant had a weaker interaction with HSP70. However, in sharp contrast, a phosphomimetic CSPα(S10D/S34D) mutant, compared with WT CSPα, had a stronger interaction with HSP70. In addition, total levels of synaptosomal-associated protein (SNAP) 25, a main downstream target of the HSC70/HSP70 chaperone complex, were found to have decreased by the CSPα(S10A/S34A) mutant through increased ubiquitination of SNAP25 in PC12 cells. In the striatum of 2-year-old male PKCγ-KO mice, decreased phosphorylation levels of CSPα and decreased SNAP25 protein levels were observed. These findings indicate the phosphorylation of CSPα by PKCγ may protect the presynaptic terminal from neurodegeneration. The PKCγ-CSPα-HSC70/HSP70-SNAP25 axis, because of its role in protecting the presynaptic terminal, may provide a new therapeutic target for the treatment of PD.SIGNIFICANCE STATEMENT Cysteine string protein α (CSPα) is a protein belonging to the heat shock protein (HSP) 40 cochaperone families localized on synaptic vesicles, which maintain the presynaptic terminal. However, the function of CSPα phosphorylation by protein kinase C (PKC) for neuronal cell survival remains unclear. The experiments presented here demonstrate that PKCγ phosphorylates CSPα at serine (Ser) 10 and Ser34. CSPα phosphorylation at Ser10 and Ser34 by PKCγ protects the presynaptic terminal by promoting HSP70 chaperone activity. This report suggests that CSPα phosphorylation, because of its role in modulating HSP70 chaperone activity, may be a target for the treatment of neurodegeneration.
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Neurons Export Extracellular Vesicles Enriched in Cysteine String Protein and Misfolded Protein Cargo. Sci Rep 2017; 7:956. [PMID: 28424476 PMCID: PMC5430488 DOI: 10.1038/s41598-017-01115-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/27/2017] [Indexed: 12/20/2022] Open
Abstract
The fidelity of synaptic transmission depends on the integrity of the protein machinery at the synapse. Unfolded synaptic proteins undergo refolding or degradation in order to maintain synaptic proteostasis and preserve synaptic function, and buildup of unfolded/toxic proteins leads to neuronal dysfunction. Many molecular chaperones contribute to proteostasis, but one in particular, cysteine string protein (CSPα), is critical for proteostasis at the synapse. In this study we report that exported vesicles from neurons contain CSPα. Extracellular vesicles (EV’s) have been implicated in a wide range of functions. However, the functional significance of neural EV’s remains to be established. Here we demonstrate that co-expression of CSPα with the disease-associated proteins, polyglutamine expanded protein 72Q huntingtinex°n1 or superoxide dismutase-1 (SOD-1G93A) leads to the cellular export of both 72Q huntingtinex°n1 and SOD-1G93A via EV’s. In contrast, the inactive CSPαHPD-AAA mutant does not facilitate elimination of misfolded proteins. Furthermore, CSPα-mediated export of 72Q huntingtinex°n1 is reduced by the polyphenol, resveratrol. Our results indicate that by assisting local lysosome/proteasome processes, CSPα-mediated removal of toxic proteins via EVs plays a central role in synaptic proteostasis and CSPα thus represents a potential therapeutic target for neurodegenerative diseases.
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Huerta-García E, Márquez-Ramírez SG, Ramos-Godinez MDP, López-Saavedra A, Herrera LA, Parra A, Alfaro-Moreno E, Gómez EO, López-Marure R. Internalization of titanium dioxide nanoparticles by glial cells is given at short times and is mainly mediated by actin reorganization-dependent endocytosis. Neurotoxicology 2015; 51:27-37. [PMID: 26340880 DOI: 10.1016/j.neuro.2015.08.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 08/27/2015] [Accepted: 08/27/2015] [Indexed: 01/12/2023]
Abstract
Many nanoparticles (NPs) have toxic effects on multiple cell lines. This toxicity is assumed to be related to their accumulation within cells. However, the process of internalization of NPs has not yet been fully characterized. In this study, the cellular uptake, accumulation, and localization of titanium dioxide nanoparticles (TiO2 NPs) in rat (C6) and human (U373) glial cells were analyzed using time-lapse microscopy (TLM) and transmission electron microscopy (TEM). Cytochalasin D (Cyt-D) was used to evaluate whether the internalization process depends of actin reorganization. To determine whether the NP uptake is mediated by phagocytosis or macropinocytosis, nitroblue tetrazolium (NBT) reduction was measured and the 5-(N-ethyl-N-isopropyl)-amiloride was used. Expression of proteins involved with endocytosis and exocytosis such as caveolin-1 (Cav-1) and cysteine string proteins (CSPs) was also determined using flow cytometry. TiO2 NPs were taken up by both cell types, were bound to cellular membranes and were internalized at very short times after exposure (C6, 30 min; U373, 2h). During the uptake process, the formation of pseudopodia and intracellular vesicles was observed, indicating that this process was mediated by endocytosis. No specific localization of TiO2 NPs into particular organelles was found: in contrast, they were primarily localized into large vesicles in the cytoplasm. Internalization of TiO2 NPs was strongly inhibited by Cyt-D in both cells and by amiloride in U373 cells; besides, the observed endocytosis was not associated with NBT reduction in either cell type, indicating that macropinocytosis is the main process of internalization in U373 cells. In addition, increases in the expression of Cav-1 protein and CSPs were observed. In conclusion, glial cells are able to internalize TiO2 NPs by a constitutive endocytic mechanism which may be associated with their strong cytotoxic effect in these cells; therefore, TiO2 NPs internalization and their accumulation in brain cells could be dangerous to human health.
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Affiliation(s)
- Elizabeth Huerta-García
- Departamento de Fisiología (Biología Celular), Instituto Nacional de Cardiología "Ignacio Chávez", Mexico; Departamento de Posgrado, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico
| | - Sandra Gissela Márquez-Ramírez
- Departamento de Fisiología (Biología Celular), Instituto Nacional de Cardiología "Ignacio Chávez", Mexico; Departamento de Posgrado, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico
| | | | | | - Luis Alonso Herrera
- Unidad de Investigación Biomédica en Cáncer, Instituto Nacional de Cancerología, Mexico; Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico
| | - Alberto Parra
- Departamento de Inmunología, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico
| | - Ernesto Alfaro-Moreno
- Laboratorio de Toxicología Ambiental, Subdirección de Investigación Básica, Instituto Nacional de Cancerología, Mexico(h); Swedish Toxicology Sciences Research Center (Swetox), Södertälje, Sweden
| | - Erika Olivia Gómez
- Academia de Biología, Colegio de Ciencias y Humanidades, Universidad Autónoma de la Ciudad de México, Mexico
| | - Rebeca López-Marure
- Departamento de Fisiología (Biología Celular), Instituto Nacional de Cardiología "Ignacio Chávez", Mexico.
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Donnelier J, Braun ST, Dolzhanskaya N, Ahrendt E, Braun AP, Velinov M, Braun JEA. Increased Expression of the Large Conductance, Calcium-Activated K+ (BK) Channel in Adult-Onset Neuronal Ceroid Lipofuscinosis. PLoS One 2015; 10:e0125205. [PMID: 25905915 PMCID: PMC4407904 DOI: 10.1371/journal.pone.0125205] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 02/17/2015] [Indexed: 01/18/2023] Open
Abstract
Cysteine string protein (CSPα) is a presynaptic J protein co-chaperone that opposes neurodegeneration. Mutations in CSPα (i.e., Leu115 to Arg substitution or deletion (Δ) of Leu116) cause adult neuronal ceroid lipofuscinosis (ANCL), a dominantly inherited neurodegenerative disease. We have previously demonstrated that CSPα limits the expression of large conductance, calcium-activated K+ (BK) channels in neurons, which may impact synaptic excitability and neurotransmission. Here we show by western blot analysis that expression of the pore-forming BKα subunit is elevated ~2.5 fold in the post-mortem cortex of a 36-year-old patient with the Leu116∆ CSPα mutation. Moreover, we find that the increase in BKα subunit level is selective for ANCL and not a general feature of neurodegenerative conditions. While reduced levels of CSPα are found in some postmortem cortex specimens from Alzheimer's disease patients, we find no concomitant increase in BKα subunit expression in Alzheimer's specimens. Both CSPα monomer and oligomer expression are reduced in synaptosomes prepared from ANCL cortex compared with control. In a cultured neuronal cell model, CSPα oligomers are short lived. The results of this study indicate that the Leu116∆ mutation leads to elevated BKα subunit levels in human cortex and extend our initial work in rodent models demonstrating the modulation of BKα subunit levels by the same CSPα mutation. While the precise sequence of pathogenic events still remains to be elucidated, our findings suggest that dysregulation of BK channels may contribute to neurodegeneration in ANCL.
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Affiliation(s)
- Julien Donnelier
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Samuel T. Braun
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | | | - Eva Ahrendt
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Andrew P. Braun
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Milen Velinov
- Albert Einstein College of Medicine, Bronx, New York, United States of America
- New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, United States of America
| | - Janice E. A. Braun
- Department of Biochemistry and Molecular Biology, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
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8
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Burgoyne RD, Morgan A. Cysteine string protein (CSP) and its role in preventing neurodegeneration. Semin Cell Dev Biol 2015; 40:153-9. [PMID: 25800794 PMCID: PMC4447612 DOI: 10.1016/j.semcdb.2015.03.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 03/16/2015] [Indexed: 11/25/2022]
Abstract
Cysteine string protein (CSP) is a member of the DnaJ/Hsp40 family of co-chaperones that localises to neuronal synaptic vesicles. Its name derives from the possession of a string of 12–15 cysteine residues, palmitoylation of which is required for targeting to post-Golgi membranes. The DnaJ domain of CSP enables it to bind client proteins and recruit Hsc70 chaperones, thereby contributing to the maintenance of protein folding in the presynaptic compartment. Mutation of CSP in flies, worms and mice reduces lifespan and causes synaptic dysfunction and neurodegeneration. Furthermore, recent studies have revealed that the neurodegenerative disease, adult onset neuronal ceroid lipofuscinosis, is caused by mutations in the human CSPα-encoding DNAJC5 gene. Accumulating evidence suggests that the major mechanism by which CSP prevents neurodegeneration is by maintaining the conformation of SNAP-25, thereby facilitating its entry into the membrane-fusing SNARE complex. In this review, we focus on the role of CSP in preventing neurodegeneration and discuss how recent studies of this universal neuroprotective chaperone are being translated into potential novel therapeutics for neurodegenerative diseases.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St., Liverpool L69 3BX, UK
| | - Alan Morgan
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St., Liverpool L69 3BX, UK.
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Proft J, Weiss N. G protein regulation of neuronal calcium channels: back to the future. Mol Pharmacol 2014; 87:890-906. [PMID: 25549669 DOI: 10.1124/mol.114.096008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 12/30/2014] [Indexed: 11/22/2022] Open
Abstract
Neuronal voltage-gated calcium channels have evolved as one of the most important players for calcium entry into presynaptic endings responsible for the release of neurotransmitters. In turn, and to fine-tune synaptic activity and neuronal communication, numerous neurotransmitters exert a potent negative feedback over the calcium signal provided by G protein-coupled receptors. This regulation pathway of physiologic importance is also extensively exploited for therapeutic purposes, for instance in the treatment of neuropathic pain by morphine and other μ-opioid receptor agonists. However, despite more than three decades of intensive research, important questions remain unsolved regarding the molecular and cellular mechanisms of direct G protein inhibition of voltage-gated calcium channels. In this study, we revisit this particular regulation and explore new considerations.
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Affiliation(s)
- Juliane Proft
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Norbert Weiss
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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10
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Donnelier J, Braun JEA. CSPα-chaperoning presynaptic proteins. Front Cell Neurosci 2014; 8:116. [PMID: 24808827 PMCID: PMC4010753 DOI: 10.3389/fncel.2014.00116] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 04/09/2014] [Indexed: 12/11/2022] Open
Abstract
Synaptic transmission relies on precisely regulated and exceedingly fast protein-protein interactions that involve voltage-gated channels, the exocytosis/endocytosis machinery as well as signaling pathways. Although we have gained an ever more detailed picture of synaptic architecture much remains to be learned about how synapses are maintained. Synaptic chaperones are “folding catalysts” that preserve proteostasis by regulating protein conformation (and therefore protein function) and prevent unwanted protein-protein interactions. Failure to maintain synapses is an early hallmark of several degenerative diseases. Cysteine string protein (CSPα) is a presynaptic vesicle protein and molecular chaperone that has a central role in preventing synaptic loss and neurodegeneration. Over the past few years, a number of different “client proteins” have been implicated as CSPα substrates including voltage-dependent ion channels, signaling proteins and proteins critical to the synaptic vesicle cycle. Here we review the ion channels and synaptic protein complexes under the influence of CSPα and discuss gaps in our current knowledge.
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Affiliation(s)
- Julien Donnelier
- Department of Physiology and Pharmacology, The Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary Calgary, AB, Canada
| | - Janice E A Braun
- Department of Physiology and Pharmacology, The Hotchkiss Brain Institute, Faculty of Medicine, University of Calgary Calgary, AB, Canada
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11
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The large conductance, calcium-activated K+ (BK) channel is regulated by cysteine string protein. Sci Rep 2014; 3:2447. [PMID: 23945775 PMCID: PMC3744087 DOI: 10.1038/srep02447] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 07/26/2013] [Indexed: 11/08/2022] Open
Abstract
Large-conductance, calcium-activated-K(+) (BK) channels are widely distributed throughout the nervous system, where they regulate action potential duration and firing frequency, along with presynaptic neurotransmitter release. Our recent efforts to identify chaperones that target neuronal ion channels have revealed cysteine string protein (CSPα) as a key regulator of BK channel expression and current density. CSPα is a vesicle-associated protein and mutations in CSPα cause the hereditary neurodegenerative disorder, adult-onset autosomal dominant neuronal ceroid lipofuscinosis (ANCL). CSPα null mice show 2.5 fold higher BK channel expression compared to wild type mice, which is not seen with other neuronal channels (i.e. Cav2.2, Kv1.1 and Kv1.2). Furthermore, mutations in either CSPα's J domain or cysteine string region markedly increase BK expression and current amplitude. We conclude that CSPα acts to regulate BK channel expression, and consequently CSPα-associated changes in BK activity may contribute to the pathogenesis of neurodegenerative disorders, such as ANCL.
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12
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Ahrendt E, Kyle B, Braun AP, Braun JEA. Cysteine string protein limits expression of the large conductance, calcium-activated K⁺ (BK) channel. PLoS One 2014; 9:e86586. [PMID: 24475152 PMCID: PMC3903548 DOI: 10.1371/journal.pone.0086586] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 12/15/2013] [Indexed: 01/12/2023] Open
Abstract
Large-conductance, calcium-activated K+ (BK) channels are widely distributed throughout the nervous system and play an essential role in regulation of action potential duration and firing frequency, along with neurotransmitter release at the presynaptic terminal. We have previously demonstrated that select mutations in cysteine string protein (CSPα), a presynaptic J-protein and co-chaperone, increase BK channel expression. This observation raised the possibility that wild-type CSPα normally functions to limit neuronal BK channel expression. Here we show by Western blot analysis of transfected neuroblastoma cells that when BK channels are present at elevated levels, CSPα acts to reduce expression. Moreover, we demonstrate that the accessory subunits, BKβ4 and BKβ1 do not alter CSPα-mediated reduction of expressed BKα subunits. Structure-function analysis reveals that the N-terminal J-domain of CSPα is critical for the observed regulation of BK channels levels. Finally, we demonstrate that CSPα limits BK current amplitude, while the loss-of-function homologue CSPαHPD-AAA increases BK current. Our observations indicate that CSPα has a role in regulating synaptic excitability and neurotransmission by limiting expression of BK channels.
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Affiliation(s)
- Eva Ahrendt
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Barry Kyle
- Libin Cardiovascular Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Andrew P. Braun
- Libin Cardiovascular Institute, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Janice E. A. Braun
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
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13
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Atlas D. The Voltage-Gated Calcium Channel Functions as the Molecular Switch of Synaptic Transmission. Annu Rev Biochem 2013; 82:607-35. [DOI: 10.1146/annurev-biochem-080411-121438] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Daphne Atlas
- Department of Biological Chemistry, Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel;
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14
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Boczek T, Lisek M, Kowalski A, Pikula S, Niewiarowska J, Wiktorska M, Zylinska L. Downregulation of PMCA2 or PMCA3 reorganizes Ca(2+) handling systems in differentiating PC12 cells. Cell Calcium 2012; 52:433-44. [PMID: 22921123 DOI: 10.1016/j.ceca.2012.08.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 07/30/2012] [Accepted: 08/02/2012] [Indexed: 01/02/2023]
Abstract
Changes in PMCA2 and PMCA3 expression during neuronal development are tightly linked to structural and functional modifications in Ca(2+) handling machinery. Using antisense strategy we obtained stably transfected PC12 lines with reduced level of PMCA2 or PMCA3, which were then subjected to dibutyryl-cAMP differentiation. Reduced level of neuron-specific PMCAs led to acceleration of differentiation and formation of longer neurites than in control PC12 line. Treatment with dibutyryl-cAMP was associated with retraction of growth cones and intensified formation of varicosities. In PMCA2-reduced cells development of apoptosis and DNA laddering were detected. Higher amounts of constitutive isoforms PMCA1 and PMCA4, their putative extended location to gaps left after partial removal of PMCA2 or PMCA3, together with increased SERCA may indicate the induction of compensatory mechanism in modified cells. Functional studies showed altered expression of certain types of VDCCs in PMCA-reduced cells, which correlated with their higher contribution to Ca(2+) influx. The cell response to PMCAs suppression suggests the interplay between transcription level of two opposite calcium-transporting systems i.e. voltage- and store depletion-activated channels facilitating Ca(2+) influx and calcium pumps responsible for Ca(2+) clearance, as well highlights the role of both neuron-specific PMCA isoforms in the control of PC12 cells differentiation.
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Affiliation(s)
- Tomasz Boczek
- Department of Molecular Neurochemistry, Medical University, Lodz, Poland.
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15
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Zhang YQ, Henderson MX, Colangelo CM, Ginsberg SD, Bruce C, Wu T, Chandra SS. Identification of CSPα clients reveals a role in dynamin 1 regulation. Neuron 2012; 74:136-50. [PMID: 22500636 DOI: 10.1016/j.neuron.2012.01.029] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/27/2012] [Indexed: 01/05/2023]
Abstract
Cysteine string protein α (CSPα), a presynaptic cochaperone for Hsc70, is required for synapse maintenance. Deletion of CSPα leads to neuronal dysfunction, synapse loss, and neurodegeneration. We utilized unbiased, systematic proteomics to identify putative CSPα protein clients. We found 22 such proteins whose levels are selectively decreased in CSPα knockout synapses. Of these putative CSPα protein clients, two directly bind to the CSPα chaperone complex and are bona fide clients. They are the t-SNARE SNAP-25 and the GTPase dynamin 1, which are necessary for synaptic vesicle fusion and fission, respectively. Using hippocampal cultures, we show that CSPα regulates the stability of client proteins and synaptic vesicle number. Our analysis of CSPα-dynamin 1 interactions reveals unexpectedly that CSPα regulates the polymerization of dynamin 1. CSPα, therefore, participates in synaptic vesicle endocytosis and may facilitate exo- and endocytic coupling. These findings advance the understanding of how synapses are functionally and structurally maintained.
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Affiliation(s)
- Yong-Quan Zhang
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Department of Neurology, Yale University, New Haven, CT 06536, USA
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16
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Regulation of voltage-gated calcium channels by synaptic proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:759-75. [PMID: 22453968 DOI: 10.1007/978-94-007-2888-2_33] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Calcium entry through neuronal voltage-gated calcium channels into presynaptic nerve terminal is a key step in synaptic exocytosis. In order to receive the calcium signal and trigger fast, efficient and spatially delimited neurotransmitter release, the vesicle-docking/release machinery must be located near the calcium source. In many cases, this close localization is achieved by a direct interaction of several members of the vesicle release machinery with the calcium channels. In turn, the binding of synaptic proteins to presynaptic calcium channels modulates channel activity to provide fine control over calcium entry, and thus modulates synaptic strength. In this chapter we summarize our present knowledge of the molecular mechanisms by which synaptic proteins regulate presynaptic calcium channel activity.
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17
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Abstract
Cysteine-string protein (CSP), a member of the DnaJ/Hsp40 family of cochaperones, is critical for maintaining neurotransmitter release and preventing neurodegeneration. CSP likely forms a chaperone complex on synaptic vesicles together with the 70-kDa heat shock cognate (Hsc70) and the small glutamine-rich tetratricopeptide repeat (TPR)-containing protein (SGT) that may control or protect the assembly and activity of SNARE proteins and various other protein substrates. Here, the author summarizes studies that elucidated CSP's neuroprotective role.
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Affiliation(s)
- Konrad E Zinsmaier
- Department of Neuroscience and Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721-0077, USA.
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18
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Johnson JN, Ahrendt E, Braun JEA. CSPalpha: the neuroprotective J protein. Biochem Cell Biol 2010; 88:157-65. [PMID: 20453918 DOI: 10.1139/o09-124] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cysteine string protein (CSPalpha, also called DnaJC5) is unique among J proteins. Similar to other J proteins, CSPalpha interacts with and activates the ATPase of Hsc70s (heat shock proteins of 70 kDa), thereby harnessing the ATPase activity for conformational work on client proteins. In contrast to other J proteins, CSPalpha is anchored to synaptic vesicles, as well as to exocrine, endocrine and neuroendocrine secretory granules, and has been shown to have an essential anti-neurodegenerative role. CSPalpha-null organisms exhibit progressive neurodegeneration, behavioural deficits, and premature death, most likely due to the progressive misfolding of one or more client proteins. Here we highlight recent advances in our understanding of the critical role that CSPalpha plays in governing exocytotic secretory functions.
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Affiliation(s)
- Jadah N Johnson
- Department of Physiology and Pharmacology and the Hotchkiss Brain Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
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19
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Boal F, Laguerre M, Milochau A, Lang J, Scotti PA. A charged prominence in the linker domain of the cysteine‐string protein Cspα mediates its regulated interaction with the calcium sensor synaptotagmin 9 during exocytosis. FASEB J 2010; 25:132-43. [DOI: 10.1096/fj.09-152033] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Frédéric Boal
- Department of BiochemistrySchool of Medical SciencesUniversity of BristolBristolUK
| | - Michel Laguerre
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 5248Universitedé Bordeaux IPessacFrance
| | - Alexandra Milochau
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 5248Universitedé Bordeaux IPessacFrance
| | - Jochen Lang
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 5248Universitedé Bordeaux IPessacFrance
| | - Pier A. Scotti
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 5248Universitedé Bordeaux IPessacFrance
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20
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Xu F, Proft J, Gibbs S, Winkfein B, Johnson JN, Syed N, Braun JEA. Quercetin targets cysteine string protein (CSPalpha) and impairs synaptic transmission. PLoS One 2010; 5:e11045. [PMID: 20548785 PMCID: PMC2883571 DOI: 10.1371/journal.pone.0011045] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 05/21/2010] [Indexed: 01/25/2023] Open
Abstract
Background Cysteine string protein (CSPα) is a synaptic vesicle protein that displays unique anti-neurodegenerative properties. CSPα is a member of the conserved J protein family, also called the Hsp40 (heat shock protein of 40 kDa) protein family, whose importance in protein folding has been recognized for many years. Deletion of the CSPα in mice results in knockout mice that are normal for the first 2–3 weeks of life followed by an unexplained presynaptic neurodegeneration and premature death. How CSPα prevents neurodegeneration is currently not known. As a neuroprotective synaptic vesicle protein, CSPα represents a promising therapeutic target for the prevention of neurodegenerative disorders. Methodology/Principal Findings Here, we demonstrate that the flavonoid quercetin promotes formation of stable CSPα-CSPα dimers and that quercetin-induced dimerization is dependent on the unique cysteine string region. Furthermore, in primary cultures of Lymnaea neurons, quercetin induction of CSPα dimers correlates with an inhibition of synapse formation and synaptic transmission suggesting that quercetin interfers with CSPα function. Quercetin's action on CSPα is concentration dependent and does not promote dimerization of other synaptic proteins or other J protein family members and reduces the assembly of CSPα:Hsc70 units (70kDa heat shock cognate protein). Conclusions/Significance Quercetin is a plant derived flavonoid and popular nutritional supplement proposed to prevent memory loss and altitude sickness among other ailments, although its precise mechanism(s) of action has been unclear. In view of the therapeutic promise of upregulation of CSPα and the undesired consequences of CSPα dysfunction, our data establish an essential proof of principle that pharmaceutical agents can selectively target the neuroprotective J protein CSPα.
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Affiliation(s)
- Fenglian Xu
- Department of Anatomy and Cell Biology, University of Calgary, Calgary, Alberta, Canada
| | - Juliane Proft
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Sarah Gibbs
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Bob Winkfein
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Jadah N. Johnson
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
| | - Naweed Syed
- Department of Anatomy and Cell Biology, University of Calgary, Calgary, Alberta, Canada
| | - Janice E. A. Braun
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
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21
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Gorleku OA, Chamberlain LH. Palmitoylation and Testis-Enriched Expression of the Cysteine-String Protein β Isoform. Biochemistry 2010; 49:5308-13. [DOI: 10.1021/bi100550h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Oforiwa A. Gorleku
- Centre for Integrative Physiology, School of Biomedical Sciences, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Luke H. Chamberlain
- Centre for Integrative Physiology, School of Biomedical Sciences, Hugh Robson Building, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
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22
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Gundersen CB, Kohan SA, Souda P, Whitelegge JP, Umbach JA. Cysteine string protein β is prominently associated with nerve terminals and secretory organelles in mouse brain. Brain Res 2010; 1332:1-11. [DOI: 10.1016/j.brainres.2010.03.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Revised: 02/26/2010] [Accepted: 03/14/2010] [Indexed: 11/16/2022]
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23
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Schmidt BZ, Watts RJ, Aridor M, Frizzell RA. Cysteine string protein promotes proteasomal degradation of the cystic fibrosis transmembrane conductance regulator (CFTR) by increasing its interaction with the C terminus of Hsp70-interacting protein and promoting CFTR ubiquitylation. J Biol Chem 2008; 284:4168-78. [PMID: 19098309 DOI: 10.1074/jbc.m806485200] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cysteine string protein (Csp) is a J-domain-containing protein whose overexpression blocks the exit of cystic fibrosis transmembrane conductance regulator (CFTR) from the endoplasmic reticulum (ER). Another method of blocking ER exit, the overexpression of Sar1-GTP, however, yielded twice as much immature CFTR compared with Csp overexpression. This finding suggested that Csp not only inhibits CFTR ER exit but also facilitates the degradation of immature CFTR. This was confirmed by treatment with a proteasome inhibitor, which returned the level of immature CFTR to that found in cells expressing Sar1-GTP only. CspH43Q, which does not interact with Hsc70/Hsp70 efficiently, did not promote CFTR degradation, suggesting that the pro-degradative effect of Csp requires Hsc70/Hsp70 binding/activation. In agreement with this, Csp overexpression increased the amount of Hsc70/Hsp70 co-immunoprecipitated with CFTR, whereas overexpression of CspH43Q did not. The Hsc70/Hsp70 binding partner C terminus of Hsp70-interacting protein (CHIP) can target CFTR for proteasome-mediated degradation. Csp overexpression also increased the amount of CHIP co-immunoprecipitated with CFTR. In addition, CHIP interacted directly with Csp, which was confirmed by in vitro binding experiments. Csp overexpression also increased CFTR ubiquitylation and reduced the half-life of immature CFTR. These findings indicate that Csp not only regulates the exit of CFTR from the ER, but that this action is accompanied by Hsc70/Hsp70 and CHIP-mediated CFTR degradation.
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Affiliation(s)
- Béla Z Schmidt
- Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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24
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Ruiz R, Casañas JJ, Südhof TC, Tabares L. Cysteine string protein-alpha is essential for the high calcium sensitivity of exocytosis in a vertebrate synapse. Eur J Neurosci 2008; 27:3118-31. [PMID: 18598257 DOI: 10.1111/j.1460-9568.2008.06301.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cysteine string protein (CSPalpha) is a synaptic vesicle protein present in most central and peripheral nervous system synapses. Previous studies demonstrated that the deletion of CSPalpha results in postnatal sensorial and motor impairment and premature lethality. To understand the participation of CSPalpha in neural function in vertebrates, we have studied the properties of synaptic transmission of motor terminals in wild-type and CSPalpha knockout mice. Our results demonstrate that, in the absence of CSPalpha, fast Ca2+-triggered release was not affected at postnatal day (P)14 but was dramatically reduced at P18 and P30 without a change in release kinetics. Although mutant terminals also exhibited a reduction in functional vesicle pool size by P30, further analysis showed that neurotransmission could be 'rescued' by high extracellular [Ca2+] or by the presence of a phorbol ester, suggesting that an impairment in the fusion machinery, or in vesicle recycling, was not the primary cause of the dysfunction of this synapse. The specific shift to the right of the Ca2+ dependence of synchronous release, and the lineal dependence of secretion on extracellular [Ca2+] in mutant terminals after P18, suggests that CSPalpha is indispensable for a normal Ca2+ sensitivity of exocytosis in vertebrate mature synapses.
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Affiliation(s)
- R Ruiz
- Department of Medical Physiology and Biophysics, School of Medicine, University of Seville, Avda. Sanchez Pizjuan 4, 41009 Seville, Spain
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25
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Swayne LA, Beck KE, Braun JEA. The cysteine string protein multimeric complex. Biochem Biophys Res Commun 2006; 348:83-91. [PMID: 16875662 DOI: 10.1016/j.bbrc.2006.07.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Accepted: 07/05/2006] [Indexed: 12/15/2022]
Abstract
Cysteine string protein (CSPalpha) is a member of the cellular folding machinery that is located on regulated secretory vesicles. We have previously shown that CSPalpha in association with Hsc70 (70kDa heat shock cognate protein) and SGT (small glutamine-rich tetratricopeptide repeat domain protein) is a guanine nucleotide exchange factor (GEF) for G(alphas). Association of this CSPalpha complex with N-type calcium channels, a channel key in coupling calcium influx with synaptic vesicle exocytosis, triggers tonic G protein inhibition of the channels. Syntaxin 1A, a plasma membrane SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) critical for neurotransmission, coimmunoprecipitates with the CSPalpha/G protein/N-type calcium channel complex, however the significance of syntaxin 1A as a component of this complex remains unknown. In this report, we establish that syntaxin 1A interacts with CSPalpha, Hsc70 as well as the synaptic protein interaction (synprint) region of N-type channels. We demonstrate that huntingtin(exon1), a putative biologically active fragment of huntingtin, displaces both syntaxin 1A and CSPalpha from N-type channels. Identification of the protein components of the CSPalpha/GEF system is essential in establishing its precise role in synaptic transmission.
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Affiliation(s)
- Leigh Anne Swayne
- Department of Physiology and Biophysics, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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26
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Schmitz F, Tabares L, Khimich D, Strenzke N, de la Villa-Polo P, Castellano-Muñoz M, Bulankina A, Moser T, Fernández-Chacón R, Südhof TC. CSPalpha-deficiency causes massive and rapid photoreceptor degeneration. Proc Natl Acad Sci U S A 2006; 103:2926-31. [PMID: 16477021 PMCID: PMC1413794 DOI: 10.1073/pnas.0510060103] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cysteine string protein (CSP) alpha is an abundant synaptic vesicle protein that contains a DNA-J domain characteristic of Hsp40-type cochaperones. Previous studies showed that deletion of CSPalpha in mice leads to massive lethal neurodegeneration but did not clarify how the neurodegeneration affects specific subpopulations of neurons. Here, we analyzed the effects of the CSPalpha deficiency on tonically active ribbon synapses of the retina and the inner ear. We show that CSPalpha-deficient photoreceptor terminals undergo dramatic and rapidly progressive neurodegeneration that starts before eye opening and initially does not affect other retinal synapses. These changes are associated with progressive blindness. In contrast, ribbon synapses of auditory hair cells did not exhibit presynaptic impairments in CSPalpha-deficient mice. Hair cells, but not photoreceptor cells or central neurons, express CSPbeta, thereby accounting for the lack of a hair-cell phenotype in CSPalpha knockout mice. Our data demonstrate that tonically active ribbon synapses in retina are particularly sensitive to the deletion of CSPalpha and that expression of at least one CSP isoform is essential to protect such tonically active synapses from neurodegeneration.
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Affiliation(s)
- Frank Schmitz
- *Institut für Anatomie und Zellbiologie, Universität des Saarlandes Homburg/Saar, Homburg, 66421 Saarland, Germany
- Center for Basic Neuroscience, Department of Molecular Genetics, and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Lucia Tabares
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, 41009 Sevilla, Spain
| | - Darina Khimich
- Center for Molecular Physiology of the Brain and Department of Otolaryngology, University of Göttingen, 37075 Göttingen, Germany; and
| | - Nicola Strenzke
- Center for Molecular Physiology of the Brain and Department of Otolaryngology, University of Göttingen, 37075 Göttingen, Germany; and
| | | | | | - Anna Bulankina
- Center for Molecular Physiology of the Brain and Department of Otolaryngology, University of Göttingen, 37075 Göttingen, Germany; and
| | - Tobias Moser
- Center for Molecular Physiology of the Brain and Department of Otolaryngology, University of Göttingen, 37075 Göttingen, Germany; and
| | | | - Thomas C. Südhof
- Center for Basic Neuroscience, Department of Molecular Genetics, and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
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27
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Chandra S, Gallardo G, Fernández-Chacón R, Schlüter OM, Südhof TC. Alpha-synuclein cooperates with CSPalpha in preventing neurodegeneration. Cell 2005; 123:383-96. [PMID: 16269331 DOI: 10.1016/j.cell.2005.09.028] [Citation(s) in RCA: 736] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 08/07/2005] [Accepted: 09/19/2005] [Indexed: 11/26/2022]
Abstract
Alpha-synuclein and cysteine-string protein-alpha (CSPalpha) are abundant synaptic vesicle proteins independently linked to neurodegeneration. Dominantly inherited mutations in alpha-synuclein cause Parkinson's disease, but the physiological role of alpha-synuclein remains unknown. Deletion of CSPalpha produces rapidly progressive neurodegeneration in mice, presumably because the cochaperone function of CSPalpha is essential for neuronal survival. Here, we report the surprising finding that transgenic expression of alpha-synuclein abolishes the lethality and neurodegeneration caused by deletion of CSPalpha. Conversely, ablation of endogenous synucleins exacerbates these phenotypes. Deletion of CSPalpha inhibits SNARE complex assembly; transgenic alpha-synuclein ameliorates this inhibition. In preventing neurodegeneration in CSPalpha-deficient mice, alpha-synuclein does not simply substitute for CSPalpha but acts by a downstream mechanism that requires phospholipid binding by alpha-synuclein. These observations reveal a powerful in vivo activity of alpha-synuclein in protecting nerve terminals against injury and suggest that this activity operates in conjunction with CSPalpha and SNARE proteins on the presynaptic membrane interface.
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Affiliation(s)
- Sreeganga Chandra
- Center for Basic Neuroscience, Department of Molecular Genetics, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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28
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Joglekar AP, Hay JC. Evidence for regulation of ER/Golgi SNARE complex formation by hsc70 chaperones. Eur J Cell Biol 2005; 84:529-42. [PMID: 16003907 DOI: 10.1016/j.ejcb.2004.12.028] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
SNARE proteins control intracellular membrane fusion through formation of membrane-bridging helix bundles of amphipathic SNARE motifs. Repetitive cycles of membrane fusion likely involve repetitive folding/unfolding of the SNARE motif helical structure. Despite these conformational demands, little is known about conformational regulation of SNAREs by other proteins. Here we demonstrate that hsc70 chaperones stimulate in vitro SNARE complex formation among the ER/Golgi SNAREs syntaxin 5, membrin, rbetl and sec22b, under conditions in which assembly is normally inhibited. Thus, molecular chaperones can render the SNARE motif more competent for assembly. Partially purified hsc70 fractions from brain cytosol had higher specific activities than fully purified hsc70, suggesting the involvement of unidentified cofactors. Using chemical crosslinking of cells followed by immunoprecipitation, we found that hsc70 was associated with ER/Golgi SNAREs in vivo. Consistent with a modulatory role for hsc70 in transport, we found that excess hsc70 specifically inhibited ER-to-Golgi transport in permeabilized cells.
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Affiliation(s)
- Ashwini P Joglekar
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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29
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Smith GB, Umbach JA, Hirano A, Gundersen CB. Interaction between constitutively expressed heat shock protein, Hsc 70, and cysteine string protein is important for cortical granule exocytosis in Xenopus oocytes. J Biol Chem 2005; 280:32669-75. [PMID: 16055447 PMCID: PMC3846525 DOI: 10.1074/jbc.m501806200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In many species, binding of sperm to the egg initiates cortical granule exocytosis, an event that contributes to a sustained block of polyspermy. Interestingly, cortical granule exocytosis can be elicited in immature Xenopus oocytes by the protein kinase C activator, phorbol-12-myristate-13-acetate. In this study, we investigated the role of cysteine string protein (csp) in phorbol-12-myristate-13-acetate-evoked cortical granule exocytosis. Prior work indicated that csp is associated with cortical granules of Xenopus oocytes. In oocytes exhibiting >20-fold overexpression of full-length Xenopus csp, cortical granule exocytosis was reduced by approximately 80%. However, csp overexpression did not affect constitutive exocytosis. Subcellular fractionation and confocal fluorescence microscopy revealed that little or none of the overexpressed csp was associated with cortical granules. This accumulation of csp at sites other than cortical granules suggested that mislocalized csp might sequester a protein that is important for regulated exocytosis. Because the NH2-terminal region of csp includes a J-domain, which interacts with constitutively expressed 70-kDa heat shock proteins (Hsc 70), we evaluated the effect of overexpressing the J-domain of csp. Although the native J-domain of csp inhibited cortical granule exocytosis, point mutations that interfere with J-domain binding to Hsc 70 eliminated this inhibition. These data indicate that csp interaction with Hsc 70 molecular chaperones is vital for regulated secretion in Xenopus oocytes.
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Affiliation(s)
- Geoffrey B. Smith
- Department of Molecular and Medical Pharmacology, David P. Geffen UCLA School of Medicine, Los Angeles, California 90095
| | - Joy A. Umbach
- Department of Molecular and Medical Pharmacology, David P. Geffen UCLA School of Medicine, Los Angeles, California 90095
| | - Arlene Hirano
- Departments of Neurobiology and Medicine, David P. Geffen UCLA School of Medicine, Los Angeles, California 90095
| | - Cameron B. Gundersen
- Department of Molecular and Medical Pharmacology, David P. Geffen UCLA School of Medicine, Los Angeles, California 90095
- To whom correspondence should be addressed. Tel.: 310-825-3423; Fax: 310-206-8975;
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30
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Yamada M, Yamada M, Higuchi T. Antidepressant-elicited changes in gene expression: remodeling of neuronal circuits as a new hypothesis for drug efficacy. Prog Neuropsychopharmacol Biol Psychiatry 2005; 29:999-1009. [PMID: 15975701 DOI: 10.1016/j.pnpbp.2005.03.022] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/01/2005] [Indexed: 11/17/2022]
Abstract
Although antidepressants have been used clinically for more than 50 years, no consensus has been reached concerning their precise molecular mechanism of action. Pharmacogenomics is a powerful tool that can be used to identify genes affected by antidepressants or by other effective therapeutic manipulations. Using this tool, others and we have identified as candidate molecular targets several genes or expressed sequence tags (ESTs) that are induced by chronic antidepressant treatment. In this article, we review antidepressant-elicited changes in gene expression, focusing especially on the remodeling of neuronal circuits that results. This refocusing motivates our hypothesis that this plasticity represents the mechanism for drug efficacy, and thus a causal event for clinical improvement. Defining the roles of these molecules in drug-induced neural plasticity is likely to transform the course of research on the biological basis of antidepressants. Such detailed knowledge will have profound effects on the diagnosis, prevention, and treatment of depression. Consideration of novel biological approaches beyond the "monoamine hypothesis" of depression is expected to evoke paradigm shifts in the future of antidepressant research.
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Affiliation(s)
- Mitsuhiko Yamada
- Department of Psychogeriatrics, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo 187-8553, Japan.
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31
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Natochin M, Campbell TN, Barren B, Miller LC, Hameed S, Artemyev NO, Braun JEA. Characterization of the G alpha(s) regulator cysteine string protein. J Biol Chem 2005; 280:30236-41. [PMID: 15972823 DOI: 10.1074/jbc.m500722200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cysteine string protein (CSP) is an abundant regulated secretory vesicle protein that is composed of a string of cysteine residues, a linker domain, and an N-terminal J domain characteristic of the DnaJ/Hsp40 co-chaperone family. We have shown previously that CSP associates with heterotrimeric GTP-binding proteins (G proteins) and promotes G protein inhibition of N-type Ca2+ channels. To elucidate the mechanisms by which CSP modulates G protein signaling, we examined the effects of CSP(1-198) (full-length), CSP(1-112), and CSP(1-82) on the kinetics of guanine nucleotide exchange and GTP hydrolysis. In this report, we demonstrate that CSP selectively interacts with G alpha(s) and increases steady-state GTP hydrolysis. CSP(1-198) modulation of G alpha(s) was dependent on Hsc70 (70-kDa heat shock cognate protein) and SGT (small glutamine-rich tetratricopeptide repeat domain protein), whereas modulation by CSP(1-112) was Hsc70-SGT-independent. CSP(1-112) preferentially associated with the inactive GDP-bound conformation of G alpha(s). Consistent with the stimulation of GTP hydrolysis, CSP(1-112) increased guanine nucleotide exchange of G alpha(s). The interaction of native G alpha(s) and CSP was confirmed by coimmunoprecipitation and showed that G alpha(s) associates with CSP. Furthermore, transient expression of CSP in HEK cells increased cellular cAMP levels in the presence of the beta2 adrenergic agonist isoproterenol. Together, these results demonstrate that CSP modulates G protein function by preferentially targeting the inactive GDP-bound form of G alpha(s) and promoting GDP/GTP exchange. Our results show that the guanine nucleotide exchange activity of full-length CSP is, in turn, regulated by Hsc70-SGT.
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Affiliation(s)
- Michael Natochin
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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32
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Evans GJO, Morgan A. Phosphorylation of cysteine string protein in the brain: developmental, regional and synaptic specificity. Eur J Neurosci 2005; 21:2671-80. [PMID: 15926915 DOI: 10.1111/j.1460-9568.2005.04118.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Protein phosphorylation modulates regulated exocytosis in most cells, including neurons. Cysteine string protein (CSP) has been implicated in this process because its phosphorylation on Ser10 alters its interactions with syntaxin and synaptotagmin, and because the effect of CSP overexpression on exocytosis kinetics in chromaffin cells requires phosphorylatable Ser10. To characterize CSP phosphorylation in the brain, we raised phosphospecific antibodies to Ser10. Western blotting revealed that the proportion of phosphorylated CSP (P-CSP) varies between distinct brain regions and also exhibits developmental regulation, with P-CSP highest early in development. Immunohistochemical analysis of the cerebellar cortex revealed a novel pool of P-CSP that did not colocalize with synaptic vesicle markers during early development. Strikingly, in the adult cerebellar granular layer P-CSP was highly enriched in a subset of glutamatergic synapses but undetectable in neighbouring GABA-ergic synapses. In view of the functional consequences of CSP phosphorylation, such differences could contribute to the synapse-specific regulation of neurotransmitter release.
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Affiliation(s)
- Gareth J O Evans
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Liverpool L69 3BX, UK
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Abstract
Neurons communicate with one another through the release of molecules from synaptic vesicles and large dense core granules through the process of exocytosis. During exocytosis, molecules are released to the extracellular space through a fusion pore, which can either dilate, resulting in full fusion, or close, resulting in incomplete exocytosis, often referred to as 'kiss and run' exocytosis. Recently, there has been much interest in the regulation of this process in both neurons and neuroendocrine cells. There has been much recent work that addresses the existence of incomplete exocytosis in neurons and neuroendocrine cells, as well as recent work probing the molecular components and modulation of the fusion pore.
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Affiliation(s)
- Seong An
- Yale University School of Medicine, Department of Cellular and Molecular Physiology, Sterling Hall of Medicine, B-147, 333 Cedar St, New Haven, Connecticut 06520, USA
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34
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Boal F, Zhang H, Tessier C, Scotti P, Lang J. The variable C-terminus of cysteine string proteins modulates exocytosis and protein-protein interactions. Biochemistry 2005; 43:16212-23. [PMID: 15610015 DOI: 10.1021/bi048612+] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cysteine string proteins (Csps) are vesicle proteins involved in neurotransmission and hormone exocytosis. They are composed of distinct domains: a variable N-terminus, a J-domain followed by a linker region, a cysteine-rich string, and a C-terminus which diverges among isoforms. Their precise function and interactions are not fully understood. Using insulin exocytosis as a model, we show that the linker region and the C-terminus, but not the variable N-terminus, regulate overall secretion. Moreover, endogenous Csp1 binds in a calcium-dependent manner to monomeric VAMP2, and this interaction requires the C-terminus of Csp. The interaction is isoform specific as recombinant Csp1 binds VAMP1 and VAMP7, but not VAMP3. Cross-linking in permeabilized clonal beta-cells revealed homodimerization of Csp which is stimulated by Ca(2+) and again modulated by the variant C-terminus. Our data suggest that both interactions of Csp occur during exocytosis and may explain the effect of the variant C-terminus of this chaperon protein on peptide hormone secretion.
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Affiliation(s)
- Frédéric Boal
- Institut Européen de Chimie et Biologie, Pôle Biologie Cellulaire et Moléculaire, JE 2390, 33607 Pessac/Bordeaux, France
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35
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Fernández-Chacón R, Wölfel M, Nishimune H, Tabares L, Schmitz F, Castellano-Muñoz M, Rosenmund C, Montesinos ML, Sanes JR, Schneggenburger R, Südhof TC. The Synaptic Vesicle Protein CSPα Prevents Presynaptic Degeneration. Neuron 2004; 42:237-51. [PMID: 15091340 DOI: 10.1016/s0896-6273(04)00190-4] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2003] [Revised: 02/17/2004] [Accepted: 03/05/2004] [Indexed: 10/26/2022]
Abstract
Cysteine string protein alpha (CSPalpha)--an abundant synaptic vesicle protein that contains a DNA-J domain characteristic of Hsp40 chaperones--is thought to regulate Ca2+ channels and/or synaptic vesicle exocytosis. We now show that, in young mice, deletion of CSPalpha does not impair survival and causes no significant changes in presynaptic Ca2+ currents or synaptic vesicle exocytosis as measured in the Calyx of Held synapse. At 2-4 weeks of age, however, CSPalpha-deficient mice develop a progressive, fatal sensorimotor disorder. The neuromuscular junctions and Calyx synapses of CSPalpha-deficient mice exhibit increasing neurodegenerative changes, synaptic transmission becomes severely impaired, and the mutant mice die at approximately 2 months of age. Our data suggest that CSPalpha is not essential for the normal operation of Ca2+ channels or exocytosis but acts as a presynaptic chaperone that maintains continued synaptic function, raising the possibility that enhanced CSPalpha function could attenuate neurodegenerative diseases.
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Affiliation(s)
- Rafael Fernández-Chacón
- Center for Basic Neuroscience, Department of Molecular Genetics and Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas 75390, USA
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36
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Miller LC, Swayne LA, Chen L, Feng ZP, Wacker JL, Muchowski PJ, Zamponi GW, Braun JEA. Cysteine String Protein (CSP) Inhibition of N-type Calcium Channels Is Blocked by Mutant Huntingtin. J Biol Chem 2003; 278:53072-81. [PMID: 14570907 DOI: 10.1074/jbc.m306230200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cysteine string protein (CSP), a 34-kDa molecular chaperone, is expressed on synaptic vesicles in neurons and on secretory vesicles in endocrine, neuroendocrine, and exocrine cells. CSP can be found in a complex with two other chaperones, the heat shock cognate protein Hsc70, and small glutamine-rich tetratricopeptide repeat domain protein (SGT). CSP function is vital in synaptic transmission; however, the precise nature of its role remains controversial. We have previously reported interactions of CSP with both heterotrimeric GTP-binding proteins (G proteins) and N-type calcium channels. These associations give rise to a tonic G protein inhibition of the channels. Here we have examined the effects of huntingtin fragments (exon 1) with (huntingtin(exon1/exp)) and without (huntingtin(exon1/nonexp)) expanded polyglutamine (polyQ) tracts on the CSP chaperone system. In vitro huntingtin(exon1/exp) sequestered CSP and blocked the association of CSP with G proteins. In contrast, huntingtin(exon1/nonexp) did not interact with CSP and did not alter the CSP/G protein association. Similarly, co-expression of huntingtin(exon1/exp) with CSP and N-type calcium channels eliminated CSP's tonic G protein inhibition of the channels, while coexpression of huntingtin(exon1/nonexp) did not alter the robust inhibition promoted by CSP. These results indicate that CSP's modulation of G protein inhibition of calcium channel activity is blocked in the presence of a huntingtin fragment with expanded polyglutamine tracts.
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Affiliation(s)
- Linda C Miller
- Cellular and Molecular Neurobiology Research Group, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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37
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Evans GJO, Morgan A, Burgoyne RD. Tying everything together: the multiple roles of cysteine string protein (CSP) in regulated exocytosis. Traffic 2003; 4:653-9. [PMID: 12956868 DOI: 10.1034/j.1600-0854.2003.00127.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In addition to the core vesicle fusion machinery, the SNARE proteins, a large number of regulatory proteins have been implicated in the process of Ca2+-dependent exocytosis. How these exocytotic proteins are properly targeted and how their myriad interactions are temporally and spatially coordinated is poorly understood. Cysteine string protein (CSP), a secretory vesicle membrane protein and a member of the dnaJ family of co-chaperones, may assist in performing this function. Through its interaction with the ubiquitous chaperone, Hsc70, it is thought that cysteine string protein targets chaperone complexes to the exocytotic machinery to facilitate the correct folding of polypeptides or to regulate the assembly of protein complexes. Since its discovery, there have been conflicting reports from different systems concerned with whether cysteine string protein exerts its effects on exocytosis either up- or down-stream of Ca2+-influx. In this review, we summarize recent experiments that associate cysteine string protein with the regulation of vesicle filling, vesicle docking, Ca2+-channels and the SNARE proteins themselves, hence supporting a role for cysteine string protein as a multifunctional secretory co-chaperone. In addition, we provide an update on the mammalian isoforms of cysteine string protein following the recent discovery of two novel cysteine string proteins.
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Affiliation(s)
- Gareth J O Evans
- The Physiological Laboratory, Department of Physiology, University of Liverpool, Crown St, Liverpool, L69 3BX, UK
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38
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Arien H, Wiser O, Arkin IT, Leonov H, Atlas D. Syntaxin 1A modulates the voltage-gated L-type calcium channel (Ca(v)1.2) in a cooperative manner. J Biol Chem 2003; 278:29231-9. [PMID: 12721298 DOI: 10.1074/jbc.m301401200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Syntaxin 1A (Sx1A) modifies the activity of voltage-gated Ca2+ channels acting via the cytosolic and the two vicinal cysteines (271 and 272) at the transmembrane domain. Here we show that Sx1A modulates the Lc-type Ca2+ channel, Cav1.2, in a cooperative manner, and we explore whether channel clustering or the Sx1A homodimer is responsible for this activity. Sx1A formed homodimers but, when mutated at the two vicinal transmembrane domain cysteines, was unable to either dimerize or modify the channel activity suggesting disulfide bond formation. Moreover, applying global molecular dynamic search established a theoretical prospect of generating a disulfide bond between two Sx1A transmembrane helices. Nevertheless, Sx1A activity was not correlated with Sx1A homodimer. Application of a vicinal thiol reagent, phenylarsine oxide, abolished Sx1A action indicating the accessibility of Cys-271,272 thiols. Sx1A inhibition of channel activity was restored by phenylarsine oxide antidote, 2,3-dimercaptopropanol, consistent with thiol interaction of Sx1A. In addition, the supralinear mode of channel inhibition was correlated to the monomeric form of Sx1A and was apparent only when the three channel subunits alpha11.2/alpha2delta1/beta2a were present. This functional demonstration of cooperativity suggests that the three-subunit channel responds as a cluster, and Sx1A monomers associate with a dimer (or more) of a three-subunit Ca2+ channel. Consistent with channel cluster linked to Sx1A, a conformational change driven by membrane depolarization and Ca2+ entry would rapidly be transduced to the exocytotic machinery. As shown herein, the supralinear relationship between Sx1A and the voltage-gated Ca2+ channel within the cluster could convey the cooperativity that distinguishes the process of neurotransmitter release.
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Affiliation(s)
- Hadar Arien
- Institute of Life Sciences, Department of Biological Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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39
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Miller LC, Swayne LA, Kay JG, Feng ZP, Jarvis SE, Zamponi GW, Braun JEA. Molecular determinants of cysteine string protein modulation of N-type calcium channels. J Cell Sci 2003; 116:2967-74. [PMID: 12783986 DOI: 10.1242/jcs.00595] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cysteine string proteins (CSPs) are secretory vesicle chaperones that are important for neurotransmitter release. We have previously reported an interaction of CSP with both heterotrimeric GTP-binding proteins (G proteins) and N-type calcium channels that results in a tonic G protein inhibition of the channels. In this report we directly demonstrate that two separate regions of CSP associate with G proteins. The N-terminal binding site of CSP, which includes the J domain, binds Galpha subunits but not Galphabeta subunits whereas the C terminal binding site of CSP associates with either free Galphabeta subunits or Galphabeta in complex with Galpha. The interaction of either binding site of CSP (CSP1-82 or CSP83-198) with G proteins elicits robust tonic inhibition of N-type calcium channel activity. However, CSP1-82 inhibition and CSP83-198 inhibition of calcium channels occur through distinct mechanisms. Calcium channel inhibition by CSP83-198 (but not CSP1-82) is completely blocked by co-expression of the synaptic protein interaction site (synprint) of the N-type channel, indicating that CSP83-198 inhibition is dependent on a physical interaction with the calcium channel. These results suggest that distinct binding sites of CSP can play a role in modulating G protein function and G protein inhibition of calcium channels.
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Affiliation(s)
- Linda C Miller
- Neuroscience Research Group, Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
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40
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Yamada M, Takahashi K, Tsunoda M, Nishioka G, Kudo K, Ohata H, Kamijima K, Higuchi T, Momose K, Yamada M. Differential expression of VAMP2/synaptobrevin-2 after antidepressant and electroconvulsive treatment in rat frontal cortex. THE PHARMACOGENOMICS JOURNAL 2003; 2:377-82. [PMID: 12629503 DOI: 10.1038/sj.tpj.6500135] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2002] [Revised: 06/30/2002] [Accepted: 07/07/2002] [Indexed: 11/08/2022]
Abstract
The biological basis for the therapeutic mechanisms of depression is still unknown. We have previously performed expressed-sequence tag (EST) analysis to identify some molecular machinery responsible for antidepressant effect. Then, we developed our original cDNA microarray, on which cDNA fragments identified as antidepressant-related genes/ESTs were spotted. In this study, with this microarray followed by Western blot analysis, we have demonstrated the induction of vesicle-associated membrane protein 2(VAMP2/synaptobrevin-2) in rat frontal cortex not only after chronic antidepressant treatment, but also after repeated electroconvulsive treatment. On the other hand, expression of SNAP-25 and syntaxin-1 was not changed by these treatments. These components make a soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor complex with VAMP2 and mediate the synaptic vesicle docking/fusion machinery. In conclusion, it is suggested that VAMP2/synaptobrevin-2 plays important roles in the antidepressant effects. Our results may contribute to a novel model for the therapeutic mechanism of depression and new molecular targets for the development of therapeutic agents.
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Affiliation(s)
- M Yamada
- Department of Pharmacology, Showa University School of Pharmaceutical Sciences, Tokyo, Japan.
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41
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Spafford JD, Zamponi GW. Functional interactions between presynaptic calcium channels and the neurotransmitter release machinery. Curr Opin Neurobiol 2003; 13:308-14. [PMID: 12850215 DOI: 10.1016/s0959-4388(03)00061-8] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In vertebrates, the physical coupling between presynaptic calcium channels and synaptic vesicle release proteins enhances the efficiency of neurotransmission. Recent evidence indicates that these synaptic proteins may feedback directly on synaptic release by negatively regulating calcium entry, and indirectly through pathways involving second messenger molecules. Studies of individual neurons from both vertebrates and invertebrates have provided novel insights into the roles of scaffolding proteins in calcium channel targeting and neurotransmitter release. These studies require us to expand current models of synaptic transmission.
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Affiliation(s)
- J David Spafford
- Department of Physiology and Biophysics, Cellular and Molecular Neurobiology Research Group, University of Calgary, 3330 Hospital Drive, Northwest Calgary, T2N 4N1, Canada
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42
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Swayne LA, Blattler C, Kay JG, Braun JEA. Oligomerization characteristics of cysteine string protein. Biochem Biophys Res Commun 2003; 300:921-6. [PMID: 12559961 DOI: 10.1016/s0006-291x(02)02964-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
CSP function is vital to synaptic transmission, however; the precise nature of its role remains controversial. Conflicting reports support either a role for CSP: (i) in exocytosis or (ii) in the regulation of transmembrane calcium fluxes. Here we have examined the self-association of CSP to form oligomers that are stable upon SDS-PAGE. To understand the structural requirements for CSP self-association a series of CSP deletion mutants were constructed, expressed, and purified. This analysis revealed an interesting pattern of oligomerization. Amino acids between 83 and 136 were observed to be important for self-association. The recombinant CSP oligomers as well as the CSP monomers directly associate with Ni(2+)-NTA agarose. Thus CSP-CSP interactions may be an important consideration for current working models of CSP chaperone activity at the synapse.
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Affiliation(s)
- Leigh Anne Swayne
- Neuroscience Research Group, Department of Physiology and Biophysics, The University of Calgary, Calgary, Alta., Canada, T2N 4N1
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43
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Arikkath J, Felix R, Ahern C, Chen CC, Mori Y, Song I, Shin HS, Coronado R, Campbell KP. Molecular characterization of a two-domain form of the neuronal voltage-gated P/Q-type calcium channel alpha(1)2.1 subunit. FEBS Lett 2002; 532:300-8. [PMID: 12482583 DOI: 10.1016/s0014-5793(02)03693-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We characterized the neuronal two-domain (95kD-alpha(1)2.1) form of the alpha(1)2.1 subunit of the voltage-gated calcium channels using genetic and molecular analysis. The 95kD-alpha(1)2.1 is absent in neuronal preparations from CACNA1A null mouse demonstrating that alpha(1)2.1 and 95kD-alpha(1)2.1 arise from the same gene. A recombinant two-domain form (alpha(1AI-II)) of alpha(1)2.1 associates with the beta subunit and is trafficked to the plasma membrane. Translocation of the alpha(1AI-II) to the plasma membrane requires association with the beta subunit, since a mutation in the alpha(1AI-II) that inhibits beta subunit association reduces membrane trafficking. Though the alpha(1AI-II) protein does not conduct any voltage-gated currents, we have previously shown that it generates a high density of non-linear charge movements [Ahern et al., Proc. Natl. Acad. Sci. USA 98 (2001) 6935-6940]. In this study, we demonstrate that co-expression of the alpha(1AI-II) significantly reduces the current amplitude of alpha(1)2.1/beta(1a)/alpha(2)delta channels, via competition for the beta subunit. Taken together, our results demonstrate a dual functional role for the alpha(1AI-II) protein, both as a voltage sensor and modulator of P/Q-type currents in recombinant systems. These studies suggest an in vivo role for the 95kD-alpha(1)2.1 in altering synaptic activity via protein-protein interactions and/or regulation of P/Q-type currents.
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Affiliation(s)
- Jyothi Arikkath
- Howard Hughes Medical Institute, Department of Physiology, University of Iowa College of Medicine, 400 Eckstein Medical Research Building, Iowa City, IA 52242-1101, USA
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44
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Jarvis SE, Barr W, Feng ZP, Hamid J, Zamponi GW. Molecular determinants of syntaxin 1 modulation of N-type calcium channels. J Biol Chem 2002; 277:44399-407. [PMID: 12221094 DOI: 10.1074/jbc.m206902200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously reported that syntaxin 1A, a component of the presynaptic SNARE complex, directly modulates N-type calcium channel gating in addition to promoting tonic G-protein inhibition of the channels, whereas syntaxin 1B affects channel gating but does not support G-protein modulation (Jarvis, S. E., and Zamponi, G. W. (2001) J. Neurosci. 21, 2939-2948). Here, we have investigated the molecular determinants that govern the action of syntaxin 1 isoforms on N-type calcium channel function. In vitro evidence shows that both syntaxin 1 isoforms physically interact with the G-protein beta subunit and the synaptic protein interaction (synprint) site contained within the N-type calcium channel domain II-III linker region. Moreover, in vitro evidence suggests that distinct domains of syntaxin participate in each interaction, with the COOH-terminal SNARE domain (residues 183-230) binding to Gbeta and the N-terminal (residues 1-69) binding to the synprint motif of the channel. Electrophysiological analysis of chimeric syntaxin 1A/1B constructs reveals that the variable NH(2)-terminal domains of syntaxin 1 are responsible for the differential effects of syntaxin 1A and 1B on N-type calcium channel function. Because syntaxin 1 exists in both "open" and "closed" conformations during exocytosis, we produced a constitutively open form of syntaxin 1A and found that it still promoted G-protein inhibition of the channels, but it did not affect N-type channel availability. This state dependence of the ability of syntaxin 1 to mediate N-type calcium channel availability suggests that syntaxin 1 dynamically regulates N-type channel function during various steps of exocytosis. Finally, syntaxin 1A appeared to compete with Ggamma for the Gbeta subunit both in vitro and under physiological conditions, suggesting that syntaxin 1A may contain a G-protein gamma subunit-like domain.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, Surface/genetics
- Antigens, Surface/metabolism
- Antigens, Surface/physiology
- Blotting, Western
- Brain/metabolism
- Calcium Channels, N-Type/metabolism
- Cattle
- Cloning, Molecular
- Dose-Response Relationship, Drug
- Electrophoresis, Polyacrylamide Gel
- Glutathione Transferase/metabolism
- Models, Biological
- Models, Molecular
- Molecular Sequence Data
- Mutation
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Nerve Tissue Proteins/physiology
- Patch-Clamp Techniques
- Polymerase Chain Reaction
- Protein Binding
- Protein Conformation
- Protein Structure, Tertiary
- Rats
- Recombinant Fusion Proteins/metabolism
- Sequence Homology, Amino Acid
- Syntaxin 1
- Transfection
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45
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Zhang H, Peters KW, Sun F, Marino CR, Lang J, Burgoyne RD, Frizzell RA. Cysteine string protein interacts with and modulates the maturation of the cystic fibrosis transmembrane conductance regulator. J Biol Chem 2002; 277:28948-58. [PMID: 12039948 DOI: 10.1074/jbc.m111706200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-regulated chloride channel whose phosphorylation regulates both channel gating and its trafficking at the plasma membrane. Cysteine string proteins (Csps) are J-domain-containing, membrane-associated proteins that have been functionally implicated in regulated exocytosis. Therefore, we evaluated the possibility that Csp is involved in regulated CFTR trafficking. We found Csp expressed in mammalian epithelial cell lines, several of which express CFTR. In Calu-3 airway cells, immunofluorescence colocalized Csp with calnexin in the endoplasmic reticulum and with CFTR at the apical membrane domain. CFTR coprecipitated with Csp from Calu-3 cell lysates. Csp associated with both core-glycosylated immature and fully glycosylated mature CFTRs (bands B and C); however, in relation to the endogenous levels of the B and C bands expressed in Calu-3 cells, the Csp interaction with band B predominated. In vitro protein binding assays detected physical interactions of both mammalian Csp isoforms with the CFTR R-domain and the N terminus, having submicromolar affinities. In Xenopus oocytes expressing CFTR, Csp overexpression decreased the chloride current and membrane capacitance increases evoked by cAMP stimulation and decreased the levels of CFTR protein detected by immunoblot. In mammalian cells, the steady-state expression of CFTR band C was eliminated, and pulse-chase studies showed that Csp coexpression blocked the conversion of immature to mature CFTR and stabilized band B. These results demonstrate a primary role for Csp in CFTR protein maturation. The physical interaction of this Hsc70-binding protein with immature CFTR, its localization in the endoplasmic reticulum, and the decrease in production of mature CFTR observed during Csp overexpression reflect a role for Csp in CFTR biogenesis. The documented role of Csp in regulated exocytosis, its interaction with mature CFTR, and its coexpression with CFTR at the apical membrane domain of epithelial cells may reflect also a role for Csp in regulated CFTR trafficking at the plasma membrane.
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Affiliation(s)
- Hui Zhang
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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46
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Evans GJO, Morgan A. Phosphorylation-dependent interaction of the synaptic vesicle proteins cysteine string protein and synaptotagmin I. Biochem J 2002; 364:343-7. [PMID: 11931641 PMCID: PMC1222577 DOI: 10.1042/bj20020123] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2002] [Revised: 03/20/2002] [Accepted: 04/04/2002] [Indexed: 11/17/2022]
Abstract
The secretory vesicle cysteine string proteins (CSPs) are members of the DnaJ family of chaperones, and function at late stages of Ca2+-regulated exocytosis by an unknown mechanism. To determine novel binding partners of CSPs, we employed a pull-down strategy from purified rat brain membrane or cytosolic proteins using recombinant hexahistidine-tagged (His(6)-)CSP. Western blotting of the CSP-binding proteins identified synaptotagmin I to be a putative binding partner. Furthermore, pull-down assays using cAMP-dependent protein kinase (PKA)-phosphorylated CSP recovered significantly less synaptotagmin. Complexes containing CSP and synaptotagmin were immunoprecipitated from rat brain membranes, further suggesting that these proteins interact in vivo. Binding assays in vitro using recombinant proteins confirmed a direct interaction between the two proteins and demonstrated that the PKA-phosphorylated form of CSP binds synaptotagmin with approximately an order of magnitude lower affinity than the non-phosphorylated form. Genetic studies have implicated each of these proteins in the Ca2+-dependency of exocytosis and, since CSP does not bind Ca2+, this novel interaction might explain the Ca2+-dependent actions of CSP.
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Affiliation(s)
- Gareth J O Evans
- The Physiological Laboratory, Department of Physiology, University of Liverpool, Crown St., Liverpool, L69 3BX, UK.
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47
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Eybalin M, Renard N, Aure F, Safieddine S. Cysteine-string protein in inner hair cells of the organ of Corti: synaptic expression and upregulation at the onset of hearing. Eur J Neurosci 2002; 15:1409-20. [PMID: 12028351 DOI: 10.1046/j.1460-9568.2002.01978.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cysteine-string protein is a vesicle-associated protein that plays a vital function in neurotransmitter release. We have studied its expression and regulation during cochlear maturation. Both the mRNA and the protein were found in primary auditory neurons and the sensory inner hair cells. More importantly, cysteine-string protein was localized on synaptic vesicles associated with the synaptic ribbon in inner hair cells and with presynaptic differentiations in lateral and medial olivocochlear terminals -- the cell bodies of which lie in the auditory brainstem. No cysteine-string protein was expressed by the sensory outer hair cells suggesting that the distinct functions of the two cochlear hair cell types imply different mechanisms of neurotransmitter release. In developmental studies in the rat, we observed that cysteine-string protein was present beneath the inner hair cells at birth and beneath outer hair cells by postnatal day 2 only. We found no expression in the inner hair cells before about postnatal day 12, which corresponds to the period during which the first cochlear action potentials could be recorded. In conclusion, the close association of cysteine-string protein with synaptic vesicles tethered to synaptic ribbons in inner hair cells and its synchronized expression with the appearance and maturation of the cochlear potentials strongly suggest that this protein plays a fundamental role in sound-evoked glutamate release by inner hair cells. This also suggests that this role may be common to ribbon synapses and conventional central nervous system synapses.
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MESH Headings
- Aging/metabolism
- Animals
- Animals, Newborn
- Cell Differentiation/physiology
- Gene Expression Regulation, Developmental/genetics
- Guinea Pigs
- HSP40 Heat-Shock Proteins
- Hair Cells, Auditory, Inner/cytology
- Hair Cells, Auditory, Inner/growth & development
- Hair Cells, Auditory, Inner/metabolism
- Hearing/physiology
- Immunohistochemistry
- Membrane Proteins/genetics
- Membrane Proteins/isolation & purification
- Membrane Proteins/metabolism
- Microscopy, Electron
- Molecular Sequence Data
- Neurotransmitter Agents/metabolism
- Organ of Corti/metabolism
- Organ of Corti/ultrastructure
- Parvalbumins/metabolism
- Presynaptic Terminals/metabolism
- Presynaptic Terminals/ultrastructure
- RNA, Messenger/metabolism
- Rats
- Sequence Homology, Amino Acid
- Spiral Ganglion/metabolism
- Spiral Ganglion/ultrastructure
- Synapses/metabolism
- Synapses/ultrastructure
- Synaptic Transmission/physiology
- Synaptic Vesicles/metabolism
- Synaptic Vesicles/ultrastructure
- Synaptophysin/metabolism
- Up-Regulation/physiology
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Affiliation(s)
- Michel Eybalin
- INSERM U. 254 and Université Montpellier 1, 34090 Montpellier, France.
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Identification and characterization of novel human Ca(v)2.2 (alpha 1B) calcium channel variants lacking the synaptic protein interaction site. J Neurosci 2002. [PMID: 11756491 DOI: 10.1523/jneurosci.22-01-00082.2002] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The physical interaction between the presynaptic vesicle release complex and the large cytoplasmic region linking domains II and III of N-type (Ca(v)2.2) calcium channel alpha(1)B subunits is considered to be of fundamental importance for efficient neurotransmission. By PCR analysis of human brain cDNA libraries and IMR32 cell mRNA, we have isolated novel N-type channel variants, termed Ca(v)2.2-Delta1 and Delta2, which lack large parts of the domain II-III linker region, including the synaptic protein interaction site. They appear to be widely expressed across the human CNS as indicated by RNase protection assays. When expressed in tsA-201 cells, both novel variants formed barium-permeable channels with voltage dependences and kinetics for activation that were similar to those observed with the full-length channel. All three channel types exhibited the hallmarks of prepulse facilitation, which interestingly occurred independently of G-protein betagamma subunits. By contrast, the voltage dependence of steady-state inactivation seen with both Delta1 and Delta2 channels was shifted toward more depolarized potentials, and recovery from inactivation of Delta1 and Delta2 channels occurred more rapidly than that of the full-length channel. Moreover, the Delta1 channel was dramatically less sensitive to both omega-conotoxin MVIIA and GVIA than either the Delta2 variant or the full-length construct. Finally, the domain II-III linker region of neither variant was able to effectively bind syntaxin in vitro. These results suggest that the structure of the II-III linker region is an important determinant of N-type channel function and pharmacology. The lack of syntaxin binding hints at a unique physiological function of these channels.
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Jarvis SE, Zamponi GW. Interactions between presynaptic Ca2+ channels, cytoplasmic messengers and proteins of the synaptic vesicle release complex. Trends Pharmacol Sci 2001; 22:519-25. [PMID: 11583809 DOI: 10.1016/s0165-6147(00)01800-9] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Influx of Ca(2+) through presynaptic voltage-gated Ca(2+) channels is a key step in rapid neurotransmitter release. The amount of Ca(2+) entering through these channels is modulated by a plethora of intracellular messenger molecules, including betagamma-subunits of G proteins, and protein kinases. In addition, Ca(2+) channels bind physically to proteins of the vesicle-release machinery in a Ca(2+)-dependent manner, which can, in turn, regulate the activity of Ca(2+) channels. Recent evidence suggests that second messengers and presynaptic vesicle-release proteins do not regulate Ca(2+) channel activity as independent entities, but that there is extensive crosstalk between these two mechanisms. The complex interactions between second messengers, vesicle-release proteins and voltage-gated Ca(2+) channels might provide multiple avenues for fine-tuning Ca(2+) entry into the presynaptic terminal and, consequently, neurotransmission.
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Affiliation(s)
- S E Jarvis
- Dept. of Physiology and Biophysics, University of Calgary, 3330 Hospital Drive NW, T2N 4N1, Calgary, Canada
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Tobaben S, Thakur P, Fernández-Chacón R, Südhof TC, Rettig J, Stahl B. A trimeric protein complex functions as a synaptic chaperone machine. Neuron 2001; 31:987-99. [PMID: 11580898 DOI: 10.1016/s0896-6273(01)00427-5] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We identify a chaperone complex composed of (1) the synaptic vesicle cysteine string protein (CSP), thought to function in neurotransmitter release, (2) the ubiquitous heat-shock protein cognate Hsc70, and (3) the SGT protein containing three tandem tetratricopeptide repeats. These three proteins interact with each other to form a stable trimeric complex that is located on the synaptic vesicle surface, and is disrupted in CSP knockout mice. The CSP/SGT/Hsc70 complex functions as an ATP-dependent chaperone that reactivates a denatured substrate. SGT overexpression in cultured neurons inhibits neurotransmitter release, suggesting that the CSP/SGT/Hsc70 complex is important for maintenance of a normal synapse. Taken together, our results identify a novel trimeric complex that functions as a synapse-specific chaperone machine.
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Affiliation(s)
- S Tobaben
- Max-Planck-Institute for Experimental Medicine, 37075 Göttingen, Germany
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