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Li T, Cheng Q, Wang S, Ma C. Rabphilin 3A binds the N-peptide of SNAP-25 to promote SNARE complex assembly in exocytosis. eLife 2022; 11:e79926. [PMID: 36173100 PMCID: PMC9522249 DOI: 10.7554/elife.79926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 09/13/2022] [Indexed: 11/13/2022] Open
Abstract
Exocytosis of secretory vesicles requires the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and small GTPase Rabs. As a Rab3/Rab27 effector protein on secretory vesicles, Rabphilin 3A was implicated to interact with SNAP-25 to regulate vesicle exocytosis in neurons and neuroendocrine cells, yet the underlying mechanism remains unclear. In this study, we have characterized the physiologically relevant binding sites between Rabphilin 3A and SNAP-25. We found that an intramolecular interplay between the N-terminal Rab-binding domain and C-terminal C2AB domain enables Rabphilin 3A to strongly bind the SNAP-25 N-peptide region via its C2B bottom α-helix. Disruption of this interaction significantly impaired docking and fusion of vesicles with the plasma membrane in rat PC12 cells. In addition, we found that this interaction allows Rabphilin 3A to accelerate SNARE complex assembly. Furthermore, we revealed that this interaction accelerates SNARE complex assembly via inducing a conformational switch from random coils to α-helical structure in the SNAP-25 SNARE motif. Altogether, our data suggest that the promotion of SNARE complex assembly by binding the C2B bottom α-helix of Rabphilin 3A to the N-peptide of SNAP-25 underlies a pre-fusion function of Rabphilin 3A in vesicle exocytosis.
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Affiliation(s)
- Tianzhi Li
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and TechnologyWuhanChina
| | - Qiqi Cheng
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and TechnologyWuhanChina
| | - Shen Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and TechnologyWuhanChina
| | - Cong Ma
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and TechnologyWuhanChina
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2
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Bourgeois-Jaarsma Q, Miaja Hernandez P, Groffen AJ. Ca 2+ sensor proteins in spontaneous release and synaptic plasticity: Limited contribution of Doc2c, rabphilin-3a and synaptotagmin 7 in hippocampal glutamatergic neurons. Mol Cell Neurosci 2021; 112:103613. [PMID: 33753311 DOI: 10.1016/j.mcn.2021.103613] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 03/09/2021] [Accepted: 03/13/2021] [Indexed: 11/28/2022] Open
Abstract
Presynaptic neurotransmitter release is strictly regulated by SNARE proteins, Ca2+ and a number of Ca2+ sensors including synaptotagmins (Syts) and Double C2 domain proteins (Doc2s). More than seventy years after the original description of spontaneous release, the mechanism that regulates this process is still poorly understood. Syt-1, Syt7 and Doc2 proteins contribute predominantly, but not exclusively, to synchronous, asynchronous and spontaneous phases of release. The proteins share a conserved tandem C2 domain architecture, but are functionally diverse in their subcellular location, Ca2+-binding properties and protein interactions. In absence of Syt-1, Doc2a and -b, neurons still exhibit spontaneous vesicle fusion which remains Ca2+-sensitive, suggesting the existence of additional sensors. Here, we selected Doc2c, rabphilin-3a and Syt-7 as three potential Ca2+ sensors for their sequence homology with Syt-1 and Doc2b. We genetically ablated each candidate gene in absence of Doc2a and -b and investigated spontaneous and evoked release in glutamatergic hippocampal neurons, cultured either in networks or on microglial islands (autapses). The removal of Doc2c had no effect on spontaneous or evoked release. Syt-7 removal also did not affect spontaneous release, although it altered short-term plasticity by accentuating short-term depression. The removal of rabphilin caused an increased spontaneous release frequency in network cultures, an effect that was not observed in autapses. Taken together, we conclude that Doc2c and Syt-7 do not affect spontaneous release of glutamate in hippocampal neurons, while our results suggest a possible regulatory role of rabphilin-3a in neuronal networks. These findings importantly narrow down the repertoire of synaptic Ca2+ sensors that may be implicated in the spontaneous release of glutamate.
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Affiliation(s)
- Quentin Bourgeois-Jaarsma
- Department of Functional Genomics, Faculty of Science, Center for Neurogenomics and Cognitive Research, VU University, De Boelelaan 1085, 1081HV Amsterdam, the Netherlands
| | - Pablo Miaja Hernandez
- Department of Functional Genomics, Faculty of Science, Center for Neurogenomics and Cognitive Research, VU University, De Boelelaan 1085, 1081HV Amsterdam, the Netherlands
| | - Alexander J Groffen
- Department of Functional Genomics, Faculty of Science, Center for Neurogenomics and Cognitive Research, VU University, De Boelelaan 1085, 1081HV Amsterdam, the Netherlands; Department of Clinical Genetics, VU Medical Center, De Boelelaan 1085, 1081HV Amsterdam, the Netherlands.
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3
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Yasuda Y, Iwama S, Kiyota A, Izumida H, Nakashima K, Iwata N, Ito Y, Morishita Y, Goto M, Suga H, Banno R, Enomoto A, Takahashi M, Arima H, Sugimura Y. Critical role of rabphilin-3A in the pathophysiology of experimental lymphocytic neurohypophysitis. J Pathol 2018; 244:469-478. [PMID: 29377134 DOI: 10.1002/path.5046] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 01/04/2018] [Accepted: 01/09/2018] [Indexed: 12/17/2023]
Abstract
Autoimmune hypophysitis (AH) is thought to be an autoimmune disease characterized by lymphocytic infiltration of the pituitary gland. Among AH pathologies, lymphocytic infundibulo-neurohypophysitis (LINH) involves infiltration of the neurohypophysis and/or the hypothalamic infundibulum, causing central diabetes insipidus resulting from insufficiency of arginine vasopressin secretion. The pathophysiological and pathogenetic mechanisms underlying LINH are largely unknown. Clinically, differentiating LINH from other pituitary diseases accompanied by mass lesions, including tumours, has often been difficult, because of similar clinical manifestations. We recently reported that rabphilin-3A is an autoantigen and that anti-rabphilin-3A antibodies constitute a possible diagnostic marker for LINH. However, the involvement of rabphilin-3A in the pathogenesis of LINH remains to be elucidated. This study was undertaken to explore the role of rabphilin-3A in lymphocytic neurohypophysitis and to investigate the mechanism. We found that immunization of mice with rabphilin-3A led to neurohypophysitis. Lymphocytic infiltration was observed in the neurohypophysis and supraoptic nucleus 1 month after the first immunization. Mice immunized with rabphilin-3A showed an increase in the volume of urine that was hypotonic as compared with control mice. Administration of a cocktail of monoclonal anti-rabphilin-3A antibodies did not induce neurohypophysitis. However, abatacept, which is a chimeric protein that suppresses T-cell activation, decreased the number of T cells specific for rabphilin-3A in peripheral blood mononuclear cells (PBMCs). It ameliorated lymphocytic infiltration of CD3+ T cells in the neurohypophysis of mice that had been immunized with rabphilin-3A. Additionally, there was a linear association between the number of T cells specific for rabphilin-3A in PBMCs and the number of CD3+ T cells infiltrating the neurohypophysis. In conclusion, we suggest that rabphilin-3A is a pathogenic antigen, and that T cells specific for rabphilin-3A are involved in the pathogenesis of neurohypophysitis in mice. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Yoshinori Yasuda
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shintaro Iwama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Research Centre of Health, Physical Fitness and Sports, Nagoya University, Japan
| | - Atsushi Kiyota
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hisakazu Izumida
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kohtaro Nakashima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Naoko Iwata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshihiro Ito
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshiaki Morishita
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Motomitsu Goto
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hidetaka Suga
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Ryoichi Banno
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Atsushi Enomoto
- Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Masahide Takahashi
- Department of Pathology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshihisa Sugimura
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Fujita Health University, Toyoake, Japan
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4
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Ferrer-Orta C, Pérez-Sánchez MD, Coronado-Parra T, Silva C, López-Martínez D, Baltanás-Copado J, Gómez-Fernández JC, Corbalán-García S, Verdaguer N. Structural characterization of the Rabphilin-3A-SNAP25 interaction. Proc Natl Acad Sci U S A 2017; 114:E5343-E5351. [PMID: 28634303 PMCID: PMC5502619 DOI: 10.1073/pnas.1702542114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Membrane fusion is essential in a myriad of eukaryotic cell biological processes, including the synaptic transmission. Rabphilin-3A is a membrane trafficking protein involved in the calcium-dependent regulation of secretory vesicle exocytosis in neurons and neuroendocrine cells, but the underlying mechanism remains poorly understood. Here, we report the crystal structures and biochemical analyses of Rabphilin-3A C2B-SNAP25 and C2B-phosphatidylinositol 4,5-bisphosphate (PIP2) complexes, revealing how Rabphilin-3A C2 domains operate in cooperation with PIP2/Ca2+ and SNAP25 to bind the plasma membrane, adopting a conformation compatible to interact with the complete SNARE complex. Comparisons with the synaptotagmin1-SNARE show that both proteins contact the same SNAP25 surface, but Rabphilin-3A uses a unique structural element. Data obtained here suggest a model to explain the Ca2+-dependent fusion process by membrane bending with a myriad of variations depending on the properties of the C2 domain-bearing protein, shedding light to understand the fine-tuning control of the different vesicle fusion events.
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Affiliation(s)
- Cristina Ferrer-Orta
- Structural Biology Unit, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Cientificas, 08028 Barcelona, Spain;
| | - María Dolores Pérez-Sánchez
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Veterinaria, Regional Campus of International Excellence "Campus Mare Nostrum," Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca, 30100 Murcia, Spain
| | - Teresa Coronado-Parra
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Veterinaria, Regional Campus of International Excellence "Campus Mare Nostrum," Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca, 30100 Murcia, Spain
| | - Cristina Silva
- Structural Biology Unit, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Cientificas, 08028 Barcelona, Spain
| | - David López-Martínez
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Veterinaria, Regional Campus of International Excellence "Campus Mare Nostrum," Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca, 30100 Murcia, Spain
| | - Jesús Baltanás-Copado
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Veterinaria, Regional Campus of International Excellence "Campus Mare Nostrum," Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca, 30100 Murcia, Spain
| | - Juan Carmelo Gómez-Fernández
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Veterinaria, Regional Campus of International Excellence "Campus Mare Nostrum," Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca, 30100 Murcia, Spain
| | - Senena Corbalán-García
- Departamento de Bioquímica y Biología Molecular-A, Facultad de Veterinaria, Regional Campus of International Excellence "Campus Mare Nostrum," Universidad de Murcia, Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca, 30100 Murcia, Spain
| | - Núria Verdaguer
- Structural Biology Unit, Institut de Biologia Molecular de Barcelona, Consejo Superior de Investigaciones Cientificas, 08028 Barcelona, Spain;
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5
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Pinheiro PS, Houy S, Sørensen JB. C2-domain containing calcium sensors in neuroendocrine secretion. J Neurochem 2016; 139:943-958. [DOI: 10.1111/jnc.13865] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 09/17/2016] [Accepted: 10/05/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Paulo S. Pinheiro
- Center for Neuroscience and Cell Biology; University of Coimbra; Coimbra Portugal
| | - Sébastien Houy
- Department of Neuroscience and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Jakob B. Sørensen
- Department of Neuroscience and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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6
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Satoh K, Oti T, Katoh A, Ueta Y, Morris JF, Sakamoto T, Sakamoto H. In vivoprocessing and release into the circulation of GFP fusion protein in arginine vasopressin enhanced GFP transgenic rats: response to osmotic stimulation. FEBS J 2015; 282:2488-99. [DOI: 10.1111/febs.13291] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 03/20/2015] [Accepted: 03/30/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Keita Satoh
- Ushimado Marine Institute; Graduate School of Natural Science and Technology; Okayama University; Japan
| | - Takumi Oti
- Ushimado Marine Institute; Graduate School of Natural Science and Technology; Okayama University; Japan
| | - Akiko Katoh
- Department of Physiology; School of Medicine; University of Occupational and Environmental Health; Kitakyushu Japan
| | - Yoichi Ueta
- Department of Physiology; School of Medicine; University of Occupational and Environmental Health; Kitakyushu Japan
| | - John F. Morris
- Department of Physiology; Anatomy and Genetics; Le Gros Clark Building; University of Oxford; UK
| | - Tatsuya Sakamoto
- Ushimado Marine Institute; Graduate School of Natural Science and Technology; Okayama University; Japan
| | - Hirotaka Sakamoto
- Ushimado Marine Institute; Graduate School of Natural Science and Technology; Okayama University; Japan
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7
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Aoki R, Kitaguchi T, Oya M, Yanagihara Y, Sato M, Miyawaki A, Tsuboi T. Duration of fusion pore opening and the amount of hormone released are regulated by myosin II during kiss-and-run exocytosis. Biochem J 2010; 429:497-504. [PMID: 20528772 DOI: 10.1042/bj20091839] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Since the fusion pore of the secretory vesicle is resealed before complete dilation during 'kiss-and-run' exocytosis, their cargoes are not completely released. Although the transient fusion pore is kept open for several seconds, the precise mechanisms that control fusion pore maintenance, and their physiological significance, are not well understood. Using dual-colour TIRF (total internal reflection fluorescence) microscopy in neuroendocrine PC12 cells, we show that myosin II regulates the fusion pore dynamics during kiss-and-run exocytosis. The release kinetics of mRFP (monomeric red fluorescent protein)-tagged tPA (tissue plasminogen activator) and Venus-tagged BDNF (brain-derived neurotrophic factor), which show slower release kinetics than NPY (neuropeptide Y)-mRFP and insulin-mRFP, were prolonged by the overexpression of a wild-type form of the RLC (myosin II regulatory light chain). In contrast, overexpression of a dominant-negative form of RLC shortened the release kinetics. Using spH (synapto-pHluorin), a green fluorescent protein-based pH sensor inside the vesicles, we confirmed that the modulation of the release kinetics by myosin II is due to changes in the duration of fusion pore opening. In addition, we revealed that the amount of hormone released into the extracellular space upon stimulation was increased by overexpression of wild-type RLC. We propose that the duration of fusion pore opening is regulated by myosin II to control the amount of hormone released from a single vesicle.
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Affiliation(s)
- Ryo Aoki
- Department of Life Sciences, The University of Tokyo, Meguro, Japan
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8
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Sato M, Mori Y, Matsui T, Aoki R, Oya M, Yanagihara Y, Fukuda M, Tsuboi T. Role of the polybasic sequence in the Doc2alpha C2B domain in dense-core vesicle exocytosis in PC12 cells. J Neurochem 2010; 114:171-81. [PMID: 20403080 DOI: 10.1111/j.1471-4159.2010.06739.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The double C2 (Doc2) family is characterized by an N-terminal Munc13-1-interacting domain and C-terminal tandem C2 domains, and it comprises three isoforms, Doc2alpha, Doc2beta, and Doc2gamma, in humans and mice. Doc2alpha, the best-characterized, brain-specific isoform, exhibits Ca(2+)-dependent phospholipid-binding activity through its C2A domain, and the Ca(2+)-binding activity is thought to be important for the regulation of Ca(2+)-dependent exocytosis. In contrast to the C2A domain, however, nothing is known about the physiological functions of the C2B domain in regulated exocytosis. In this study, we demonstrated by a mutation analysis that the polybasic sequence in the C2B domain of Doc2alpha (306 KKSKHKTCVKKK 317) is required for binding of syntaxin-1a/synaptosome-associated protein of 25 kDa (SNAP-25) heterodimer. We also investigated the effect of Lys-to-Gln (named KQ) mutations in the polybasic sequence of the C2B domain on vesicle dynamics by total internal reflection fluorescence microscopy in PC12 cells. A Doc2alpha(KQ) mutant, which lacks binding activity toward syntaxin-1a/SNAP-25 heterodimer, significantly decreased the number of plasma membrane-docked vesicles before stimulation and strongly inhibited high-KCl-induced exocytosis from the plasma membrane-docked vesicles. These results indicate that the polybasic sequence in the C2B domain functions as a binding site for syntaxin-1a/SNAP-25 heterodimer and controls the number of 'readily releasable' vesicles in neuroendocrine cells.
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Affiliation(s)
- Mai Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo, Japan
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Tsuboi T, Kitaguchi T, Karasawa S, Fukuda M, Miyawaki A. Age-dependent preferential dense-core vesicle exocytosis in neuroendocrine cells revealed by newly developed monomeric fluorescent timer protein. Mol Biol Cell 2010; 21:87-94. [PMID: 19889833 PMCID: PMC2801723 DOI: 10.1091/mbc.e09-08-0722] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 10/13/2009] [Accepted: 10/28/2009] [Indexed: 11/11/2022] Open
Abstract
Although it is evident that only a few secretory vesicles accumulating in neuroendocrine cells are qualified to fuse with the plasma membrane and release their contents to the extracellular space, the molecular mechanisms that regulate their exocytosis are poorly understood. For example, it has been controversial whether secretory vesicles are exocytosed randomly or preferentially according to their age. Using a newly developed protein-based fluorescent timer, monomeric Kusabira Green Orange (mK-GO), which changes color with a predictable time course, here we show that small GTPase Rab27A effectors regulate age-dependent exocytosis of secretory vesicles in PC12 cells. When the vesicles were labeled with mK-GO-tagged neuropeptide Y or tissue-type plasminogen activator, punctate structures with green or red fluorescence were observed. Application of high [K(+)] stimulation induced exocytosis of new (green) fluorescent secretory vesicles but not of old (red) vesicles. Overexpression or depletion of rabphilin and synaptotagmin-like protein4-a (Slp4-a), which regulate exocytosis positively and negatively, respectively, disturbed the age-dependent exocytosis of the secretory vesicles in different manners. Our results suggest that coordinate functions of the two effectors of Rab27A, rabphilin and Slp4-a, are required for regulated secretory pathway.
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Affiliation(s)
- Takashi Tsuboi
- *Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo 153-8902, Japan
- Laboratory for Cell Function and Dynamics, Advanced Technology Development Group, Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
| | - Tetsuya Kitaguchi
- Life Function and Dynamics, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Wako, Saitama 351-0198, Japan
| | - Satoshi Karasawa
- Laboratory for Cell Function and Dynamics, Advanced Technology Development Group, Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
- Amalgaam Co., Ltd., Itabashi, Tokyo 173-0004, Japan; and
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Atsushi Miyawaki
- Laboratory for Cell Function and Dynamics, Advanced Technology Development Group, Brain Science Institute, RIKEN, Wako, Saitama 351-0198, Japan
- Life Function and Dynamics, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, Wako, Saitama 351-0198, Japan
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10
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Molecular mechanism of attachment process of dense-core vesicles to the plasma membrane in neuroendocrine cells. Neurosci Res 2009; 63:83-8. [DOI: 10.1016/j.neures.2008.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 10/27/2008] [Accepted: 11/10/2008] [Indexed: 11/21/2022]
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11
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Lee JD, Huang PC, Lin YC, Kao LS, Huang CC, Kao FJ, Lin CC, Yang DM. In-depth fluorescence lifetime imaging analysis revealing SNAP25A-Rabphilin 3A interactions. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2008; 14:507-18. [PMID: 18986604 DOI: 10.1017/s1431927608080628] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The high sensitivity and spatial resolution enabled by two-photon excitation fluorescence lifetime imaging microscopy/fluorescence resonance energy transfer (2PE-FLIM/FRET) provide an effective approach that reveals protein-protein interactions in a single cell during stimulated exocytosis. Enhanced green fluorescence protein (EGFP)-labeled synaptosomal associated protein of 25 kDa (SNAP25A) and red fluorescence protein (mRFP)-labeled Rabphillin 3A (RPH3A) were co-expressed in PC12 cells as the FRET donor and acceptor, respectively. The FLIM images of EGFP-SNAP25A suggested that SNAP25A/RPH3A interaction was increased during exocytosis. In addition, the multidimensional (three-dimensional with time) nature of the 2PE-FLIM image datasets can also resolve the protein interactions in the z direction, and we have compared several image analysis methods to extract more accurate and detailed information from the FLIM images. Fluorescence lifetime was fitted by using one and two component analysis. The lifetime FRET efficiency was calculated by the peak lifetime (taupeak) and the left side of the half-peak width (tau1/2), respectively. The results show that FRET efficiency increased at cell surface, which suggests that SNAP25A/RPH3A interactions take place at cell surface during stimulated exocytosis. In summary, we have demonstrated that the 2PE-FLIM/FRET technique is a powerful tool to reveal dynamic SNAP25A/RPH3A interactions in single neuroendocrine cells.
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Affiliation(s)
- Jiung-De Lee
- Department of Medical Research and Education, Taipei Veterans General Hospital, National Yang-Ming University, Taipei 11217, Taiwan, Republic of China
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12
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Abstract
Small GTPase Rab is a member of a large family of Ras-related proteins, highly conserved in eukaryotic cells, and thought to regulate specific type(s) and/or specific step(s) in intracellular membrane trafficking. Given our interest in synaptic transmission, we addressed the possibility that Rab27 (a close isoform of Rab3) could be involved in cytosolic synaptic vesicle mobilization. Indeed, preterminal injection of a specific antibody against squid Rab27 (anti-sqRab27 antibody) combined with confocal microscopy demonstrated that Rab27 is present on squid synaptic vesicles. Electrophysiological study of injected synapses showed that the anti-sqRab27 antibody inhibited synaptic release in a stimulation-dependent manner without affecting presynaptic action potentials or inward Ca(2+) current. This result was confirmed in in vitro synaptosomes by using total internal reflection fluorescence microscopy. Thus, synaptosomal Ca(2+)-stimulated release of FM1-43 dye was greatly impaired by intraterminal anti-sqRab27 antibody. Ultrastructural analysis of the injected giant preterminal further showed a reduced number of docked synaptic vesicles and an increase in nondocked vesicular profiles distant from the active zone. These results, taken together, indicate that Rab27 is primarily involved in the maturation of recycled vesicles and/or their transport to the presynaptic active zone in the squid giant synapse.
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13
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Handley MTW, Burgoyne RD. The Rab27 effector Rabphilin, unlike Granuphilin and Noc2, rapidly exchanges between secretory granules and cytosol in PC12 cells. Biochem Biophys Res Commun 2008; 373:275-81. [PMID: 18573236 DOI: 10.1016/j.bbrc.2008.06.043] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Accepted: 06/05/2008] [Indexed: 11/29/2022]
Abstract
Rab proteins are GTPases that transit between GTP- and GDP-bound states. In the GTP-bound form they can recruit specific effector to membrane domains. It is possible that the exchange of Rab effectors between membranes and cytosol would be determined by the exchange of the particular Rab partner. We have compared the cycling of three Rab3/27 effectors, Granuphilin, Noc2, and Rabphilin, in PC12 cells using fluorescence recovery after photobleaching of EGFP-tagged proteins. All three effectors become localised to secretory granules. Granuphilin and Noc2 showed little or no exchange between secretory granules and cytosol whereas Rabphilin showed rapid and complete exchange. Both Noc2 and Rabphilin were found to be recruited to granules by Rab27 but the data suggest that Rabphilin did not form stable complexes with Rab27 on secretory granules and so Rab effector cycling between membranes and cytosol can be independent of that of the Rab protein.
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Affiliation(s)
- Mark T W Handley
- The Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown Street, Liverpool L693BX, UK
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Coleman WL, Bill CA, Simsek-Duran F, Lonart G, Samigullin D, Bykhovskaia M. Synapsin II and calcium regulate vesicle docking and the cross-talk between vesicle pools at the mouse motor terminals. J Physiol 2008; 586:4649-73. [PMID: 18669537 DOI: 10.1113/jphysiol.2008.154666] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The synapsins, an abundant and highly conserved family of proteins that associate with synaptic vesicles, have been implicated in regulating the synaptic vesicle cycle. However, it has not been determined whether synapsin directly regulates the number of docked vesicles. Here we document that reducing Ca(2+) concentration [Ca(2+)](o) in the extracellular medium from 2 to 0.5 mm led to an approximately 40% decrease in both docked and undocked synaptic vesicles in wild-type nerve terminals of the mouse diaphragm. The same treatment reduced the number of undocked vesicles in nerve terminals derived from synapsin II gene deleted animals, but surprisingly it did not decrease vesicle docking, indicating that synapsin II inhibits docking of synaptic vesicles at reduced [Ca(2+)](o). In accordance with the morphological findings, at reduced [Ca(2+)](o) synapsin II (-) terminals had a higher rate of quantal neurotransmitter release. Microinjection of a recombinant synapsin II protein into synapsin II (-) terminals reduced vesicular docking and inhibited quantal release, indicating a direct and selective synapsin II effect for regulating vesicle docking and, in turn, quantal release. To understand why [Ca(2+)](o) has a prominent effect on synapsin function, we investigated the effect of [Ca(2+)](o) on the distribution of synaptic vesicles and on the concentration of intraterminal Ca(2+). We found that reduced [Ca(2+)](o) conditions produce a decrease in intracellular Ca(2+) and overall vesicle depletion. To explore why at these conditions the role of synapsin II in vesicle docking becomes more prominent, we developed a quantitative model of the vesicle cycle, with a two step synapsin action in stabilizing the vesicle store and regulating vesicle docking. The results of the modelling were in a good agreement with the observed dependence of vesicle distribution on synapsin II and calcium deficiency.
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Affiliation(s)
- William L Coleman
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA.
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Review: Molecular mechanism of docking of dense-core vesicles to the plasma membrane in neuroendocrine cells. Med Mol Morphol 2008; 41:68-75. [DOI: 10.1007/s00795-008-0400-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Accepted: 03/04/2008] [Indexed: 02/06/2023]
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Rappoport JZ, Heyman KP, Kemal S, Simon SM. Dynamics of dynamin during clathrin mediated endocytosis in PC12 cells. PLoS One 2008; 3:e2416. [PMID: 18545672 PMCID: PMC2409078 DOI: 10.1371/journal.pone.0002416] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2007] [Accepted: 04/28/2008] [Indexed: 11/18/2022] Open
Abstract
Background Members of the dynamin super-family of GTPases are involved in disparate cellular pathways. Dynamin1 and dynamin2 have been implicated in clathrin-mediated endocytosis. While some models suggest that dynamin functions specifically at the point of vesicle fission, evidence also exists for a role prior to fission during vesicle formation and it is unknown if there is a role for dynamin after vesicle fission. Although dynamin2 is ubiquitously expressed, dynamin1 is restricted to the nervous system. These two structurally similar endocytic accessory proteins have not been studied in cells that endogenously express both. Methodology/Principal Findings The present study quantitatively assesses the dynamics of dynamin1 and dynamin2 during clathrin-mediated endocytosis in PC12 cells, which endogenously express both proteins. Both dynamin isoforms co-localized with clathrin and showed sharp increases in fluorescence intensity immediately prior to internalization of the nascent clathrin-coated vesicle. The fluorescence intensity of both proteins then decreased with two time constants. The slower time constant closely matched the time constant for the decrease of clathrin intensity and likely represents vesicle movement away from the membrane. The faster rate may reflect release of dynamin at the neck of nascent vesicle following GTP hydrolysis. Conclusions/Significance This study analyses the role of dynamin in clathrin-mediated endocytosis in a model for cellular neuroscience and these results may provide direct evidence for the existence of two populations of dynamin associated with nascent clathrin-coated vesicles.
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Affiliation(s)
- Joshua Z. Rappoport
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, New York, United States of America
| | - Katherine P. Heyman
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, New York, United States of America
| | - Shahrnaz Kemal
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, New York, United States of America
| | - Sanford M. Simon
- Laboratory of Cellular Biophysics, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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Montaville P, Coudevylle N, Radhakrishnan A, Leonov A, Zweckstetter M, Becker S. The PIP2 binding mode of the C2 domains of rabphilin-3A. Protein Sci 2008; 17:1025-34. [PMID: 18434502 PMCID: PMC2386734 DOI: 10.1110/ps.073326608] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 02/08/2008] [Accepted: 03/10/2008] [Indexed: 01/13/2023]
Abstract
Phosphatidylinositol-4,5-bisphosphate (PIP2) is a key player in the neurotransmitter release process. Rabphilin-3A is a neuronal C2 domain tandem containing protein that is involved in this process. Both its C2 domains (C2A and C2B) are able to bind PIP2. The investigation of the interactions of the two C2 domains with the PIP2 headgroup IP3 (inositol-1,4,5-trisphosphate) by NMR showed that a well-defined binding site can be described on the concave surface of each domain. The binding modes of the two domains are different. The binding of IP3 to the C2A domain is strongly enhanced by Ca(2+) and is characterized by a K(D) of 55 microM in the presence of a saturating concentration of Ca(2+) (5 mM). Reciprocally, the binding of IP3 increases the apparent Ca(2+)-binding affinity of the C2A domain in agreement with a Target-Activated Messenger Affinity (TAMA) mechanism. The C2B domain binds IP3 in a Ca(2+)-independent fashion with low affinity. These different PIP2 headgroup recognition modes suggest that PIP2 is a target of the C2A domain of rabphilin-3A while this phospholipid is an effector of the C2B domain.
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Affiliation(s)
- Pierre Montaville
- Department of NMR-based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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Affiliation(s)
- James A McNew
- Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street MS-140, Houston, Texas 77251-1892, USA.
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Lee JD, Chang YF, Kao FJ, Kao LS, Lin CC, Lu AC, Shyu BC, Chiou SH, Yang DM. Detection of the interaction between SNAP25 and rabphilin in neuroendocrine PC12 cells using the FLIM/FRET technique. Microsc Res Tech 2008; 71:26-34. [PMID: 17886343 DOI: 10.1002/jemt.20521] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Exocytosis has been proposed to contain four sequential steps, namely docking, priming, fusion, and recycling, and to be regulated by various proteins-protein interactions. Synaptosomal-associated protein of 25 kDa (SNAP25) has recently been found to bind rabphilin, the Rab3A specific binding protein, in vitro. However, it is still unclear whether SNAP25 and rabphilin interact during exocytosis within cells in vivo. This problem was addressed by the integration of fluorescence resonance energy transfer (FRET) with high sensitivity fluorescence lifetime imaging microscopy (FLIM) to observe this protein-protein interaction. Enhanced green fluorescence protein-labeled SNAP25 (donor) and red fluorescence protein-labeled rabphilin (acceptor) were expressed in neuroendocrine PC12 cells as a FRET pair and ATP stimulation was carried out for various durations. With 10 s stimulation, a 0.17-ns left shift of the lifetime peak was found when compared with donor only. Analysis of the lifetime image further suggested that the lifetime recovered to a similar level as the donor only in a time dependent manner. Four-dimensional (4D) images by FLIM provided useful information indicating that the interaction of SNAP25 and rabphilin occurred particularly within optical sections near cell membrane. Together the results suggest that SNAP25 bound rabphilin loosely at docking step before exocytosis and the binding became tighter at the very start of exocytosis. Finally, these two proteins dissociated after stimulation. To our knowledge, this is the first report to demonstrate the interaction of SNAP25 and rabphilin in situ using the FLIM-FRET technique within neuroendocrine cells.
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Affiliation(s)
- Jiung-De Lee
- Institute of Biophotonics, School of Medical Technology and Engineering, National Yang-Ming University, Taipei, Taiwan, Republic of China
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