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Expression and subcellular localization of the Qa-SNARE syntaxin17 in human eosinophils. Exp Cell Res 2015; 337:129-135. [PMID: 26254897 DOI: 10.1016/j.yexcr.2015.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 06/29/2015] [Accepted: 07/06/2015] [Indexed: 01/21/2023]
Abstract
BACKGROUND SNARE members mediate membrane fusion during intracellular trafficking underlying innate and adaptive immune responses by different cells. However, little is known about the expression and function of these proteins in human eosinophils, cells involved in allergic, inflammatory and immunoregulatory responses. Here, we investigate the expression and distribution of the Qa-SNARE syntaxin17 (STX17) within human eosinophils isolated from the peripheral blood. METHODS Flow cytometry and a pre-embedding immunonanogold electron microscopy (EM) technique that combines optimal epitope preservation and secondary Fab-fragments of antibodies linked to 1.4 nm gold particles for optimal access to microdomains, were used to investigate STX17. RESULTS STX17 was detected within unstimulated eosinophils. Immunogold EM revealed STX17 on secretory granules and on granule-derived vesiculotubular transport carriers (Eosinophil Sombrero Vesicles-EoSVs). Quantitative EM analyses showed that 77.7% of the granules were positive for STX17 with a mean±SEM of 3.9±0.2 gold particles/granule. Labeling was present on both granule outer membranes and matrices while EoSVs showed clear membrane-associated labeling. STX17 was also present in secretory granules in eosinophils stimulated with the cytokine tumor necrosis factor alpha (TNF-α) or the CC-chemokine ligand 11 CCL11 (eotaxin-1), stimuli that induce eosinophil degranulation. The number of secretory granules labeled for STX17 was significantly higher in CCL11 compared with the unstimulated group. The level of cell labeling did not change when unstimulated cells were compared with TNF-α-stimulated eosinophils. CONCLUSIONS The present study clearly shows by immunanonogold EM that STX17 is localized in eosinophil secretory granules and transport vesicles and might be involved in the transport of granule-derived cargos.
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Abstract
Dysbindin is a schizophrenia susceptibility factor and subunit of the biogenesis of lysosome-related organelles complex 1 (BLOC-1) required for lysosome-related organelle biogenesis, and in neurons, synaptic vesicle assembly, neurotransmission, and plasticity. Protein networks, or interactomes, downstream of dysbindin/BLOC-1 remain partially explored despite their potential to illuminate neurodevelopmental disorder mechanisms. Here, we conducted a proteome-wide search for polypeptides whose cellular content is sensitive to dysbindin/BLOC-1 loss of function. We identified components of the vesicle fusion machinery as factors downregulated in dysbindin/BLOC-1 deficiency in neuroectodermal cells and iPSC-derived human neurons, among them the N-ethylmaleimide-sensitive factor (NSF). Human dysbindin/BLOC-1 coprecipitates with NSF and vice versa, and both proteins colocalized in a Drosophila model synapse. To test the hypothesis that NSF and dysbindin/BLOC-1 participate in a pathway-regulating synaptic function, we examined the role for NSF in dysbindin/BLOC-1-dependent synaptic homeostatic plasticity in Drosophila. As previously described, we found that mutations in dysbindin precluded homeostatic synaptic plasticity elicited by acute blockage of postsynaptic receptors. This dysbindin mutant phenotype is fully rescued by presynaptic expression of either dysbindin or Drosophila NSF. However, neither reduction of NSF alone or in combination with dysbindin haploinsufficiency impaired homeostatic synaptic plasticity. Our results demonstrate that dysbindin/BLOC-1 expression defects result in altered cellular content of proteins of the vesicle fusion apparatus and therefore influence synaptic plasticity.
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Kubo K, Kobayashi M, Nozaki S, Yagi C, Hatsuzawa K, Katoh Y, Shin HW, Takahashi S, Nakayama K. SNAP23/25 and VAMP2 mediate exocytic event of transferrin receptor-containing recycling vesicles. Biol Open 2015; 4:910-20. [PMID: 26092867 PMCID: PMC4571095 DOI: 10.1242/bio.012146] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We recently showed that Rab11 is involved not only in formation of recycling vesicles containing the transferrin (Tfn)–transferrin receptor (TfnR) complex at perinuclear recycling endosomes but also in tethering of recycling vesicles to the plasma membrane (PM) in concert with the exocyst tethering complex. We here aimed at identifying SNARE proteins responsible for fusion of Tfn–TfnR-containing recycling vesicles with the PM, downstream of the exocyst. We showed that exocyst subunits, Sec6 and Sec8, can interact with SNAP23 and SNAP25, both of which are PM-localizing Qbc-SNAREs, and that depletion of SNAP23 and/or SNAP25 in HeLa cells suppresses fusion of Tfn–TfnR-containing vesicles with the PM, leading to accumulation of the vesicles at the cell periphery. We also found that VAMP2, an R-SNARE, is colocalized with endocytosed Tfn on punctate endosomal structures, and that its depletion in HeLa cells suppresses recycling vesicle exocytosis. These observations indicate that fusion of recycling vesicles with the PM downstream of the exocyst is mediated by SNAP23/25 and VAMP2, and provide novel insight into non-neuronal roles of VAMP2 and SNAP25.
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Affiliation(s)
- Keiji Kubo
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Minako Kobayashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shohei Nozaki
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Chikako Yagi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kiyotaka Hatsuzawa
- Division of Molecular Biology, Tottori University School of Life Science, Yonago, Tottori 683-8503, Japan
| | - Yohei Katoh
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Hye-Won Shin
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Senye Takahashi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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SNAP23 is selectively expressed in airway secretory cells and mediates baseline and stimulated mucin secretion. Biosci Rep 2015; 35:BSR20150004. [PMID: 26182382 PMCID: PMC4613665 DOI: 10.1042/bsr20150004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 04/14/2015] [Indexed: 11/17/2022] Open
Abstract
Airway mucin secretion is important pathophysiologically and as a model of polarized epithelial regulated exocytosis. We find the trafficking protein, SNAP23 (23-kDa paralogue of synaptosome-associated protein of 25 kDa), selectively expressed in secretory cells compared with ciliated and basal cells of airway epithelium by immunohistochemistry and FACS, suggesting that SNAP23 functions in regulated but not constitutive epithelial secretion. Heterozygous SNAP23 deletant mutant mice show spontaneous accumulation of intracellular mucin, indicating a defect in baseline secretion. However mucins are released from perfused tracheas of mutant and wild-type (WT) mice at the same rate, suggesting that increased intracellular stores balance reduced release efficiency to yield a fully compensated baseline steady state. In contrast, acute stimulated release of intracellular mucin from mutant mice is impaired whether measured by a static imaging assay 5 min after exposure to the secretagogue ATP or by kinetic analysis of mucins released from perfused tracheas during the first 10 min of ATP exposure. Together, these data indicate that increased intracellular stores cannot fully compensate for the defect in release efficiency during intense stimulation. The lungs of mutant mice develop normally and clear bacteria and instilled polystyrene beads comparable to WT mice, consistent with these functions depending on baseline secretion that is fully compensated.
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55
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Ishida S, Umeyama H, Iwadate M, Taguchi YH. Bioinformatic screening of autoimmune disease genes and protein structure prediction with FAMS for drug discovery. Protein Pept Lett 2015; 21:828-39. [PMID: 23855671 PMCID: PMC4141326 DOI: 10.2174/09298665113209990052] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 02/13/2013] [Accepted: 02/14/2013] [Indexed: 01/19/2023]
Abstract
Autoimmune diseases are often intractable because their causes are unknown. Identifying which genes contribute to these diseases may allow us to understand the pathogenesis, but it is difficult to determine which genes contribute to disease. Recently, epigenetic information has been considered to activate/deactivate disease-related genes. Thus, it may also be useful to study epigenetic information that differs between healthy controls and patients with autoimmune disease. Among several types of epigenetic information, promoter methylation is believed to be one of the most important factors. Here, we propose that principal component analysis is useful to identify specific gene promoters that are differently methylated between the normal healthy controls and patients with autoimmune disease. Full Automatic Modeling System (FAMS) was used to predict the three-dimensional structures of selected proteins and successfully inferred relatively confident structures. Several possibilities of the application to the drug discovery based on obtained structures are discussed.
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Affiliation(s)
| | | | | | - Y-H Taguchi
- Department of Physics, Chuo University, Tokyo 112-8551, Japan, and Department of Biological Sciences, Chuo University, Tokyo 112-8551, Japan.
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56
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Wong M, Munro S. Membrane trafficking. The specificity of vesicle traffic to the Golgi is encoded in the golgin coiled-coil proteins. Science 2014; 346:1256898. [PMID: 25359980 DOI: 10.1126/science.1256898] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The Golgi apparatus is a multicompartment central sorting station at the intersection of secretory and endocytic vesicular traffic. The mechanisms that permit cargo-loaded transport vesicles from different origins to selectively access different Golgi compartments are incompletely understood. We developed a rerouting and capture assay to investigate systematically the vesicle-tethering activities of 10 widely conserved golgin coiled-coil proteins. We find that subsets of golgins with distinct localizations on the Golgi surface have capture activities toward vesicles of different origins. These findings demonstrate that golgins act as tethers in vivo, and hence the specificity we find to be encoded in this tethering is likely to make a major contribution to the organization of membrane traffic at the Golgi apparatus.
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Affiliation(s)
- Mie Wong
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Sean Munro
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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57
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Brandstaetter H, Kruppa AJ, Buss F. Huntingtin is required for ER-to-Golgi transport and for secretory vesicle fusion at the plasma membrane. Dis Model Mech 2014; 7:1335-40. [PMID: 25368120 PMCID: PMC4257002 DOI: 10.1242/dmm.017368] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Huntingtin is a large membrane-associated scaffolding protein that associates with endocytic and exocytic vesicles and modulates their trafficking along cytoskeletal tracks. Although the progression of Huntington’s disease is linked to toxic accumulation of mutant huntingtin protein, loss of wild-type huntingtin function might also contribute to neuronal cell death, but its precise function is not well understood. Therefore, we investigated the molecular role of huntingtin in exocytosis and observed that huntingtin knockdown in HeLa cells causes a delay in endoplasmic reticulum (ER)-to-Golgi transport and a reduction in the number of cargo vesicles leaving the trans-Golgi network. In addition, we found that huntingtin is required for secretory vesicle fusion at the plasma membrane. Similar defects in the early exocytic pathway were observed in primary fibroblasts from homozygous Htt140Q/140Q knock-in mice, which have the expansion inserted into the mouse huntingtin gene so lack wild-type huntingtin expression. Interestingly, heterozygous fibroblasts from a Huntington’s disease patient with a 180Q expansion displayed no obvious defects in the early secretory pathway. Thus, our results highlight the requirement for wild-type huntingtin at distinct steps along the secretory pathway.
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Affiliation(s)
- Hemma Brandstaetter
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Antonina J Kruppa
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
| | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK.
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58
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Ramirez DMO, Kavalali ET. The role of non-canonical SNAREs in synaptic vesicle recycling. CELLULAR LOGISTICS 2014; 2:20-27. [PMID: 22645707 PMCID: PMC3355972 DOI: 10.4161/cl.20114] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
An increasing number of studies suggest that distinct pools of synaptic vesicles drive specific forms of neurotransmission. Interspersed with these functional studies are analyses of the synaptic vesicle proteome which have consistently detected the presence of so-called “non-canonical” SNAREs that typically function in fusion and trafficking of other subcellular structures within the neuron. The recent identification of certain non-canonical vesicular SNAREs driving spontaneous (e.g., VAMP7 and vti1a) or evoked asynchronous (e.g., VAMP4) release integrates and corroborates existing data from functional and proteomic studies and implies that at least some complement of non-canonical SNAREs resident on synaptic vesicles function in neurotransmission. Here, we discuss the specific roles in neurotransmission of proteins homologous to each member of the classical neuronal SNARE complex consisting of synaptobrevin2, syntaxin-1 and SNAP-25.
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59
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Cancino J, Capalbo A, Di Campli A, Giannotta M, Rizzo R, Jung JE, Di Martino R, Persico M, Heinklein P, Sallese M, Luini A. Control systems of membrane transport at the interface between the endoplasmic reticulum and the Golgi. Dev Cell 2014; 30:280-94. [PMID: 25117681 DOI: 10.1016/j.devcel.2014.06.018] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 04/08/2014] [Accepted: 06/23/2014] [Indexed: 10/24/2022]
Abstract
A fundamental property of cellular processes is to maintain homeostasis despite varying internal and external conditions. Within the membrane transport apparatus, variations in membrane fluxes from the endoplasmic reticulum (ER) to the Golgi complex are balanced by opposite fluxes from the Golgi to the ER to maintain homeostasis between the two organelles. Here we describe a molecular device that balances transport fluxes by integrating transduction cascades with the transport machinery. Specifically, ER-to-Golgi transport activates the KDEL receptor at the Golgi, which triggers a cascade that involves Gs and adenylyl cyclase and phosphodiesterase isoforms and then PKA activation and results in the phosphorylation of transport machinery proteins. This induces retrograde traffic to the ER and balances transport fluxes between the ER and Golgi. Moreover, the KDEL receptor activates CREB1 and other transcription factors that upregulate transport-related genes. Thus, a Golgi-based control system maintains transport homeostasis through both signaling and transcriptional networks.
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Affiliation(s)
- Jorge Cancino
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy; Telethon Institute of Genetics and Medicine, Via Pietro Castellino 111, 80131 Napoli, Italy; Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Quillota 980, Viña del Mar 2520000, Chile.
| | - Anita Capalbo
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy; Telethon Institute of Genetics and Medicine, Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Antonella Di Campli
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Monica Giannotta
- Consorzio Mario Negri Sud, Via Nazionale 8/A, 66030 Santa Maria Imbaro (Chieti), Italy
| | - Riccardo Rizzo
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy; Telethon Institute of Genetics and Medicine, Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Juan E Jung
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy; Istituto di Ricovero e Cura a Carattere Scientifico, Istituto di Ricerca Diagnostica e Nucleare (SDN), 80143 Napoli, Italy
| | - Rosaria Di Martino
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy
| | - Maria Persico
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy; Istituto di Ricovero e Cura a Carattere Scientifico, Istituto di Ricerca Diagnostica e Nucleare (SDN), 80143 Napoli, Italy
| | - Petra Heinklein
- Institut für Biochemie Charité, Universitätsmedizin Berlin, CrossOver Charitéplatz 1/Sitz, Virchowweg 6, 10117 Berlin, Germany
| | - Michele Sallese
- Consorzio Mario Negri Sud, Via Nazionale 8/A, 66030 Santa Maria Imbaro (Chieti), Italy
| | - Alberto Luini
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy; Telethon Institute of Genetics and Medicine, Via Pietro Castellino 111, 80131 Napoli, Italy.
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60
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Abstract
Protein trafficking within the secretory pathway of mammalian cells is amenable to analysis by biochemical methods. This can be achieved by monitoring posttranslational modifications that occur naturally within the secretory pathway, or by measuring the delivery of cargo to the cell surface or extracellular medium. These approaches can be combined with additional manipulations such as specific temperature blocks that permit analysis of distinct trafficking steps. Biochemical analysis is advantageous in that it permits both a sensitive and quantitative measure of trafficking along the pathway. The methods discussed in this chapter permit the analysis of trafficking of both endogenous cargo proteins and ectopically expressed model cargos, which can be followed using either Western blotting or metabolic pulse-chase approaches. These methods are relatively straightforward and suitable for use in most modern cell biology laboratories. In addition to the well-established methods that we describe here in detail, we also refer to the development of more recent tailored approaches that add further to the arsenal of tools that can be used to assess trafficking in the secretory pathway.
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Affiliation(s)
- Peristera Roboti
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
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61
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Helm JR, Bentley M, Thorsen KD, Wang T, Foltz L, Oorschot V, Klumperman J, Hay JC. Apoptosis-linked gene-2 (ALG-2)/Sec31 interactions regulate endoplasmic reticulum (ER)-to-Golgi transport: a potential effector pathway for luminal calcium. J Biol Chem 2014; 289:23609-28. [PMID: 25006245 DOI: 10.1074/jbc.m114.561829] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Luminal calcium released from secretory organelles has been suggested to play a regulatory role in vesicle transport at several steps in the secretory pathway; however, its functional roles and effector pathways have not been elucidated. Here we demonstrate for the first time that specific luminal calcium depletion leads to a significant decrease in endoplasmic reticulum (ER)-to-Golgi transport rates in intact cells. Ultrastructural analysis revealed that luminal calcium depletion is accompanied by increased accumulation of intermediate compartment proteins in COPII buds and clusters of unfused COPII vesicles at ER exit sites. Furthermore, we present several lines of evidence suggesting that luminal calcium affected transport at least in part through calcium-dependent interactions between apoptosis-linked gene-2 (ALG-2) and the Sec31A proline-rich region: 1) targeted disruption of ALG-2/Sec31A interactions caused severe defects in ER-to-Golgi transport in intact cells; 2) effects of luminal calcium and ALG-2/Sec31A interactions on transport mutually required each other; and 3) Sec31A function in transport required luminal calcium. Morphological phenotypes of disrupted ALG-2/Sec31A interactions were characterized. We found that ALG-2/Sec31A interactions were not required for the localization of Sec31A to ER exit sites per se but appeared to acutely regulate the stability and trafficking of the cargo receptor p24 and the distribution of the vesicle tether protein p115. These results represent the first outline of a mechanism that connects luminal calcium to specific protein interactions regulating vesicle trafficking machinery.
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Affiliation(s)
- Jared R Helm
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Marvin Bentley
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Kevin D Thorsen
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Ting Wang
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Lauren Foltz
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
| | - Viola Oorschot
- the Cell Microscopy Center, Department of Cell Biology, University Medical Center Utrecht, AZU Room H02.313, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Judith Klumperman
- the Cell Microscopy Center, Department of Cell Biology, University Medical Center Utrecht, AZU Room H02.313, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Jesse C Hay
- From the Division of Biological Sciences and Center for Structural and Functional Neuroscience, University of Montana, Missoula, Montana 59812-4824 and
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62
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Nogueira C, Erlmann P, Villeneuve J, Santos AJ, Martínez-Alonso E, Martínez-Menárguez JÁ, Malhotra V. SLY1 and Syntaxin 18 specify a distinct pathway for procollagen VII export from the endoplasmic reticulum. eLife 2014. [PMID: 24842878 DOI: 10.7554/elife.02784.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
TANGO1 binds and exports Procollagen VII from the endoplasmic reticulum (ER). In this study, we report a connection between the cytoplasmic domain of TANGO1 and SLY1, a protein that is required for membrane fusion. Knockdown of SLY1 by siRNA arrested Procollagen VII in the ER without affecting the recruitment of COPII components, general protein secretion, and retrograde transport of the KDEL-containing protein BIP, and ERGIC53. SLY1 is known to interact with the ER-specific SNARE proteins Syntaxin 17 and 18, however only Syntaxin 18 was required for Procollagen VII export. Neither SLY1 nor Syntaxin 18 was required for the export of the equally bulky Procollagen I from the ER. Altogether, these findings reveal the sorting of bulky collagen family members by TANGO1 at the ER and highlight the existence of different export pathways for secretory cargoes one of which is mediated by the specific SNARE complex containing SLY1 and Syntaxin 18.DOI: http://dx.doi.org/10.7554/eLife.02784.001.
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Affiliation(s)
- Cristina Nogueira
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Patrik Erlmann
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Julien Villeneuve
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - António Jm Santos
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Emma Martínez-Alonso
- Department of Cellular Biology and Histology, Faculty of Medicine, University of Murcia, Murcia, Spain
| | | | - Vivek Malhotra
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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63
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Nogueira C, Erlmann P, Villeneuve J, Santos AJ, Martínez-Alonso E, Martínez-Menárguez JÁ, Malhotra V. SLY1 and Syntaxin 18 specify a distinct pathway for procollagen VII export from the endoplasmic reticulum. eLife 2014; 3:e02784. [PMID: 24842878 PMCID: PMC4054776 DOI: 10.7554/elife.02784] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
TANGO1 binds and exports Procollagen VII from the endoplasmic reticulum (ER). In this study, we report a connection between the cytoplasmic domain of TANGO1 and SLY1, a protein that is required for membrane fusion. Knockdown of SLY1 by siRNA arrested Procollagen VII in the ER without affecting the recruitment of COPII components, general protein secretion, and retrograde transport of the KDEL-containing protein BIP, and ERGIC53. SLY1 is known to interact with the ER-specific SNARE proteins Syntaxin 17 and 18, however only Syntaxin 18 was required for Procollagen VII export. Neither SLY1 nor Syntaxin 18 was required for the export of the equally bulky Procollagen I from the ER. Altogether, these findings reveal the sorting of bulky collagen family members by TANGO1 at the ER and highlight the existence of different export pathways for secretory cargoes one of which is mediated by the specific SNARE complex containing SLY1 and Syntaxin 18.DOI: http://dx.doi.org/10.7554/eLife.02784.001.
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Affiliation(s)
- Cristina Nogueira
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Patrik Erlmann
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Julien Villeneuve
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - António Jm Santos
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Emma Martínez-Alonso
- Department of Cellular Biology and Histology, Faculty of Medicine, University of Murcia, Murcia, Spain
| | | | - Vivek Malhotra
- Cell and Developmental Biology Program, Center for Genomic Regulation (CRG), Barcelona, Spain Universitat Pompeu Fabra (UPF), Barcelona, Spain Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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64
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Szalinski CM, Labilloy A, Bruns JR, Weisz OA. VAMP7 modulates ciliary biogenesis in kidney cells. PLoS One 2014; 9:e86425. [PMID: 24466086 PMCID: PMC3899255 DOI: 10.1371/journal.pone.0086425] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 12/12/2013] [Indexed: 12/02/2022] Open
Abstract
Epithelial cells elaborate specialized domains that have distinct protein and lipid compositions, including the apical and basolateral surfaces and primary cilia. Maintaining the identity of these domains is required for proper cell function, and requires the efficient and selective SNARE-mediated fusion of vesicles containing newly synthesized and recycling proteins with the proper target membrane. Multiple pathways exist to deliver newly synthesized proteins to the apical surface of kidney cells, and the post-Golgi SNAREs, or VAMPs, involved in these distinct pathways have not been identified. VAMP7 has been implicated in apical protein delivery in other cell types, and we hypothesized that this SNARE would have differential effects on the trafficking of apical proteins known to take distinct routes to the apical surface in kidney cells. VAMP7 expressed in polarized Madin Darby canine kidney cells colocalized primarily with LAMP2-positive compartments, and siRNA-mediated knockdown modulated lysosome size, consistent with the known function of VAMP7 in lysosomal delivery. Surprisingly, VAMP7 knockdown had no effect on apical delivery of numerous cargoes tested, but did decrease the length and frequency of primary cilia. Additionally, VAMP7 knockdown disrupted cystogenesis in cells grown in a three-dimensional basement membrane matrix. The effects of VAMP7 depletion on ciliogenesis and cystogenesis are not directly linked to the disruption of lysosomal function, as cilia lengths and cyst morphology were unaffected in an MDCK lysosomal storage disorder model. Together, our data suggest that VAMP7 plays an essential role in ciliogenesis and lumen formation. To our knowledge, this is the first study implicating an R-SNARE in ciliogenesis and cystogenesis.
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Affiliation(s)
- Christina M. Szalinski
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Anatália Labilloy
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- Ciência sem Fronteiras, CNPq, Brasilia, Brazil
| | - Jennifer R. Bruns
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - Ora A. Weisz
- Renal Electrolyte Division, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- Department of Cell Biology, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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65
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Ivanov AI. Pharmacological inhibitors of exocytosis and endocytosis: novel bullets for old targets. Methods Mol Biol 2014; 1174:3-18. [PMID: 24947371 DOI: 10.1007/978-1-4939-0944-5_1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Pharmacological inhibitors of vesicle trafficking possess great promise as valuable analytical tools for the study of a variety of biological processes and as potential therapeutic agents to fight microbial infections and cancer. However, many commonly used trafficking inhibitors are characterized by poor selectivity that diminishes their use in solving basic problems of cell biology or drug development. Recent high-throughput chemical screens intensified the search for novel modulators of vesicle trafficking, and successfully identified a number of small molecules that inhibit exocytosis and endocytosis in different types of mammalian cells. This chapter provides a systematic overview of recently discovered inhibitors of vesicle trafficking. It describes cellular effects and mechanisms of action of novel inhibitors of exocytosis and endocytosis. Furthermore, it pays special attention to the selectivity and possible off-target effects of these inhibitors.
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Affiliation(s)
- Andrei I Ivanov
- Department of Human and Molecular Genetics, VCU Institute of Molecular Medicine, Virginia Commonwealth University, Goodwin Laboratory, 401 College Street, 980035, Richmond, VA, 23298, USA,
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66
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Ruggiero C, Cancino J, Giannotta M, Sallese M. Signaling initiated by the secretory compartment. Methods Enzymol 2014; 534:133-54. [PMID: 24359952 DOI: 10.1016/b978-0-12-397926-1.00008-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Classical signal transduction is initiated at the plasma membrane by extracellular signals and propagates to the cytosolic face of the same membrane. Multiple studies have shown that endomembranes can act as signaling platforms for this plasma-membrane-originated signaling. Recent evidence has indicated that endomembranes can also trigger their own signaling cascades that involve some of the molecular players that are classically engaged in signal transduction at the plasma membrane. Endomembrane-initiated signaling is important for synchronization of the functioning of the secretory pathway and coordination of the activities of the secretory organelles with other cellular machineries. However, these endomembrane-initiated regulatory circuits are only partially understood to date. This novel field is slowed by a lack of specific tools and the objective difficulties in the study of signal transduction of endomembrane-localized receptors, as their accessibility is limited. For example, the ligand-binding site of the KDEL receptor (that transduces endomembrane signaling) is positioned in the lumen of the Golgi complex. Here we report some approaches that are suitable for the study of endomembrane-initiated signaling.
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Affiliation(s)
- Carmen Ruggiero
- Department of Cellular and Translational Pharmacology, Fondazione Mario Negri Sud, Unit of Genomic Approaches to Membrane Traffic, Santa Maria Imbaro (CH), Italy
| | - Jorge Cancino
- Department of Life Sciences, Institute of Protein Biochemistry, National Research Council and Telethon Institute of Genetics and Medicine, Naples, Italy
| | | | - Michele Sallese
- Department of Cellular and Translational Pharmacology, Fondazione Mario Negri Sud, Unit of Genomic Approaches to Membrane Traffic, Santa Maria Imbaro (CH), Italy.
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67
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Shitara A, Shibui T, Okayama M, Arakawa T, Mizoguchi I, Sakakura Y, Shakakura Y, Takuma T. VAMP4 is required to maintain the ribbon structure of the Golgi apparatus. Mol Cell Biochem 2013; 380:11-21. [PMID: 23677696 PMCID: PMC3695666 DOI: 10.1007/s11010-013-1652-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 04/11/2013] [Indexed: 10/31/2022]
Abstract
The Golgi apparatus forms a twisted ribbon-like network in the juxtanuclear region of vertebrate cells. Vesicle-associated membrane protein 4 (VAMP4), a v-SNARE protein expressed exclusively in the vertebrate trans-Golgi network (TGN), plays a role in retrograde trafficking from the early endosome to the TGN, although its precise function within the Golgi apparatus remains unclear. To determine whether VAMP4 plays a functional role in maintaining the structure of the Golgi apparatus, we depleted VAMP4 gene expression using RNA interference technology. Depletion of VAMP4 from HeLa cells led to fragmentation of the Golgi ribbon. These fragments were not uniformly distributed throughout the cytoplasm, but remained in the juxtanuclear area. Electron microscopy and immunohistochemistry showed that in the absence of VAMP4, the length of the Golgi stack was shortened, but Golgi stacking was normal. Anterograde trafficking was not impaired in VAMP4-depleted cells, which contained intact microtubule arrays. Depletion of the cognate SNARE partners of VAMP4, syntaxin 6, syntaxin 16, and Vti1a also disrupted the Golgi ribbon structure. Our findings suggested that the maintenance of Golgi ribbon structure requires normal retrograde trafficking from the early endosome to the TGN, which is likely to be mediated by the formation of VAMP4-containing SNARE complexes.
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Affiliation(s)
- Akiko Shitara
- Division of Biochemistry, Department of Oral Biology, School of Dentistry, Health Sciences University of Hokkaido, Tobetsu Hokkaido, Ishikari 061-0293, Japan.
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68
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Jacob A, Jing J, Lee J, Schedin P, Gilbert SM, Peden AA, Junutula JR, Prekeris R. Rab40b regulates trafficking of MMP2 and MMP9 during invadopodia formation and invasion of breast cancer cells. J Cell Sci 2013; 126:4647-58. [PMID: 23902685 DOI: 10.1242/jcs.126573] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Invadopodia-dependent degradation of the basement membrane plays a major role during metastasis of breast cancer cells. Basement membrane degradation is mediated by targeted secretion of various matrix metalloproteinases (MMPs). Specifically, MMP2 and MMP9 (MMP2/9) possess the ability to hydrolyze components of the basement membrane and regulate various aspects of tumor growth and metastasis. However, the membrane transport machinery that mediates targeting of MMP2/9 to the invadopodia during cancer cell invasion remains to be defined. Because Rab GTPases are key regulators of membrane transport, we screened a human Rab siRNA library and identified Rab40b GTPase as a protein required for secretion of MMP2/9. We also have shown that Rab40b functions during at least two distinct steps of MMP2/9 transport. Here, we demonstrate that Rab40b is required for MMP2/9 sorting into VAMP4-containing secretory vesicles. We also show that Rab40b regulates transport of MMP2/9 secretory vesicles during invadopodia formation and is required for invadopodia-dependent extracellular matrix degradation. Finally, we demonstrate that Rab40b is also required for breast cancer cell invasion in vitro. On the basis of these findings, we propose that Rab40b mediates trafficking of MMP2/9 during invadopodia formation and metastasis of breast cancer cells.
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Affiliation(s)
- Abitha Jacob
- Department of Cell and Developmental Biology, School of Medicine, Anschutz Medical Campus, University of Colorado Denver, Aurora, CO 80045, USA
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69
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Human genome-wide RNAi screen reveals a role for nuclear pore proteins in poxvirus morphogenesis. Proc Natl Acad Sci U S A 2013; 110:3519-24. [PMID: 23401514 DOI: 10.1073/pnas.1300708110] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Poxviruses are considered less dependent on host functions than other DNA viruses because of their cytoplasmic site of replication and large genomes, which encode enzymes for DNA and mRNA synthesis. Nevertheless, RNAi screens with two independent human genome-scale libraries have identified more than 500 candidate genes that significantly inhibited and a similar number that enhanced replication and spread of infectious vaccinia virus (VACV). Translational, ubiquitin-proteosome, and endoplasmic reticulum-to-Golgi transport functions, known to be important for VACV, were enriched in the siRNA-inhibiting group, and RNA polymerase II and associated functions were enriched in the siRNA-enhancing group. Additional findings, notably the inhibition of VACV spread by siRNAs to several nuclear pore genes, were unanticipated. Knockdown of nucleoporin 62 strongly inhibited viral morphogenesis, with only a modest effect on viral gene expression, recapitulating and providing insight into previous studies with enucleated cells.
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70
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Muppirala M, Gupta V, Swarup G. Emerging role of tyrosine phosphatase, TCPTP, in the organelles of the early secretory pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:1125-32. [PMID: 23328081 DOI: 10.1016/j.bbamcr.2013.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 01/04/2013] [Accepted: 01/08/2013] [Indexed: 01/21/2023]
Abstract
T-cell protein tyrosine phosphatase, TCPTP, is a ubiquitously expressed non-receptor type tyrosine phosphatase. There are two splice variants of TCPTP, TC48 and TC45, which differ in their sub-cellular localizations and functions. TC45 is a nuclear protein, which has both nuclear and cytoplasmic substrates, and is involved in many signaling events including endocytic recycling of platelet-derived growth factor β-receptor. TC48 is a predominantly endoplasmic reticulum (ER)-localizing protein, which dephosphorylates some of the substrates of TC45 at the ER. However, recently few specific substrates for TC48 have been identified. These include C3G (RapGEF1), syntaxin 17 and BCR-Abl. TC48 moves from the ER to post-ER compartments, the ER-Golgi intermediate compartment (ERGIC) and Golgi, and it is retrieved back to the ER. The retrieval of ER proteins from post-ER compartments is generally believed as a mechanism of targeting these proteins to the ER. However, it is possible that this shuttling of TC48 serves to regulate signaling in the early secretory pathway. For example, TC48 dephosphorylates phosphorylated C3G at the Golgi and inhibits neurite outgrowth. TC48 interacts with and dephosphorylates syntaxin 17, which is an ER and ERGIC-localizing protein involved in vesicle transport. A yeast two-hybrid screen identified several unique interacting partners of TC48 belonging to two groups - proteins involved in vesicle trafficking and proteins involved in cell adhesion. These interacting proteins could be substrates or regulators of TC48 function and localization. Thus, the role of TC48 seems to be more diverse, which is still to be explored.
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Affiliation(s)
- Madhavi Muppirala
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
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71
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Boncompain G, Perez F. Synchronizing protein transport in the secretory pathway. CURRENT PROTOCOLS IN CELL BIOLOGY 2012; Chapter 15:15.19.1-15.19.16. [PMID: 23208546 DOI: 10.1002/0471143030.cb1519s57] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
To be secreted or transported to their target compartments, newly synthesized proteins leave the endoplasmic reticulum to reach the Golgi apparatus, where they are processed and sorted toward their final destinations along the secretory pathway. It is now clear that many Golgi-intersecting and non-intersecting pathways exist in cells to carry out proper transport, modification, and addressing. To analyze and visualize the intracellular trafficking of any secretory protein, we developed the retention using selective hooks (RUSH) system. This assay allows the simultaneous release of a pool of particular secretory proteins from the endoplasmic reticulum and the monitoring of their anterograde trafficking. The use of the RUSH system is detailed in these protocols, from sub-cloning the sequence coding for the protein of interest into RUSH plasmids to visualization of its trafficking.
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Affiliation(s)
- Gaelle Boncompain
- Research Center, Institut Curie, Paris, France.,CNRS UMR144, Paris, France
| | - Franck Perez
- Research Center, Institut Curie, Paris, France.,CNRS UMR144, Paris, France
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72
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Muppirala M, Gupta V, Swarup G. Tyrosine phosphorylation of a SNARE protein, syntaxin 17: implications for membrane trafficking in the early secretory pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:2109-19. [PMID: 23006999 DOI: 10.1016/j.bbamcr.2012.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 09/13/2012] [Indexed: 10/27/2022]
Abstract
The T-cell protein tyrosine phosphatase is expressed as two splice variants - TC45, a nuclear protein, and TC48, which is localized predominantly in the ER (endoplasmic reticulum). Yeast two-hybrid screening revealed direct interaction of TC48 with Syntaxin17, a SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein localized predominantly in the ER and to some extent in the ER-Golgi intermediate compartment. Syntaxin 17 did not interact with TC45. C-terminal 40 amino acids of TC48 were sufficient for interaction with syntaxin 17. Overexpressed syntaxin 17 was phosphorylated at tyrosine upon pervanadate treatment (a tyrosine phosphatase inhibitor/tyrosine kinase activator) of COS-1 cells. Mutational analysis identified Tyr156 in the cytoplasmic domain as the major site of phosphorylation. Endogenous syntaxin 17 was phosphorylated by pervanadate treatment in CHO and MIN6 cells but was not phosphorylated in a variety of other cell lines tested. c-Abl was identified as one of the kinases, which phosphorylates syntaxin 17 in MIN6 cells. Phosphorylation of endogenous and overexpressed syntaxin 17 was reduced in the presence of IGF receptor and EGF receptor kinase inhibitors. Serum depletion reduced pervanadate-induced phosphorylation of endogenous syntaxin 17. TC48 coexpression reduced phosphorylation of syntaxin 17 by pervanadate and purified TC48 directly dephosphorylated syntaxin 17. β-COP dispersal by overexpressed syntaxin 17 was reduced after pervanadate-induced phosphorylation. A phospho-mimicking mutant (Y156E) of syntaxin 17 showed reduced interaction with COPI vesicles. These results suggest that tyrosine phosphorylation of syntaxin 17 is likely to have a role in regulating syntaxin 17 dependent membrane trafficking in the early secretory pathway.
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Affiliation(s)
- Madhavi Muppirala
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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73
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Canton J, Kima PE. Targeting host syntaxin-5 preferentially blocks Leishmania parasitophorous vacuole development in infected cells and limits experimental Leishmania infections. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:1348-55. [PMID: 22885104 DOI: 10.1016/j.ajpath.2012.06.041] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Revised: 06/06/2012] [Accepted: 06/20/2012] [Indexed: 02/08/2023]
Abstract
Our previous observations established a role for syntaxin-5 in the development of Leishmania parasitophorous vacuoles (LPVs). In this study, we took advantage of the recent identification of Retro-2, a small organic molecule that can cause the redistribution of syntaxin-5; we show herein that Retro-2 blocks LPV development within 2 hours of adding it to cells infected with Leishmania amazonensis. In infected cells incubated for 48 hours with Retro-2, LPV development was significantly limited; furthermore, infected cells harbored four to five times fewer parasites than infected cells incubated in vehicle alone. In vivo studies revealed that Retro-2 curbed experimental L. amazonensis infections in a dose-dependent manner. Retro-2 did not have any appreciable effect on the host cell physiological characteristics; furthermore, it had no apparent toxicity in experimental animals. An unexpected, but welcome, finding was that Retro-2 inhibited the replication of Leishmania parasites in axenic cultures. This study is significant because it identifies an endoplasmic reticulum/Golgi SNARE as a potential target for the control of Leishmania infections; moreover, it suggests that small organic molecules can be identified that can selectively disrupt the vesicle fusion machinery that promotes the development of pathogen-containing compartments without exerting toxic effects on the host.
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Affiliation(s)
- Johnathan Canton
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida 32611, USA
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74
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Heissler SM, Selvadurai J, Bond LM, Fedorov R, Kendrick-Jones J, Buss F, Manstein DJ. Kinetic properties and small-molecule inhibition of human myosin-6. FEBS Lett 2012; 586:3208-14. [PMID: 22884421 PMCID: PMC3527664 DOI: 10.1016/j.febslet.2012.07.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 06/23/2012] [Accepted: 07/10/2012] [Indexed: 11/12/2022]
Abstract
Myosin-6 is an actin-based motor protein that moves its cargo towards the minus-end of actin filaments. Mutations in the gene encoding the myosin-6 heavy chain and changes in the cellular abundance of the protein have been linked to hypertrophic cardiomyopathy, neurodegenerative diseases, and cancer. Here, we present a detailed kinetic characterization of the human myosin-6 motor domain, describe the effect of 2,4,6-triiodophenol on the interaction of myosin-6 with F-actin and nucleotides, and show how addition of the drug reduces the number of myosin-6-dependent vesicle fusion events at the plasma membrane during constitutive secretion.
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Affiliation(s)
- Sarah M Heissler
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
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75
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Simpson JC, Joggerst B, Laketa V, Verissimo F, Cetin C, Erfle H, Bexiga MG, Singan VR, Hériché JK, Neumann B, Mateos A, Blake J, Bechtel S, Benes V, Wiemann S, Ellenberg J, Pepperkok R. Genome-wide RNAi screening identifies human proteins with a regulatory function in the early secretory pathway. Nat Cell Biol 2012; 14:764-74. [DOI: 10.1038/ncb2510] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 04/26/2012] [Indexed: 02/06/2023]
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76
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Thayanidhi N, Liang Y, Hasegawa H, Nycz DC, Oorschot V, Klumperman J, Hay JC. R-SNARE ykt6 resides in membrane-associated protease-resistant protein particles and modulates cell cycle progression when over-expressed. Biol Cell 2012; 104:397-417. [DOI: 10.1111/boc.201100048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 03/08/2012] [Indexed: 12/11/2022]
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77
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Kent HM, Evans PR, Schäfer IB, Gray SR, Sanderson CM, Luzio JP, Peden AA, Owen DJ. Structural basis of the intracellular sorting of the SNARE VAMP7 by the AP3 adaptor complex. Dev Cell 2012; 22:979-88. [PMID: 22521722 PMCID: PMC3549491 DOI: 10.1016/j.devcel.2012.01.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 12/14/2011] [Accepted: 01/26/2012] [Indexed: 11/15/2022]
Abstract
VAMP7 is involved in the fusion of late endocytic compartments with other membranes. One possible mechanism of VAMP7 delivery to these late compartments is via the AP3 trafficking adaptor. We show that the linker of the δ-adaptin subunit of AP3 binds the VAMP7 longin domain and determines the structure of their complex. Mutation of residues on both partners abolishes the interaction in vitro and in vivo. The binding of VAMP7 to δ-adaptin requires the VAMP7 SNARE motif to be engaged in SNARE complex formation and hence AP3 must transport VAMP7 when VAMP7 is part of a cis-SNARE complex. The absence of δ-adaptin causes destabilization of the AP3 complex in mouse mocha fibroblasts and mislocalization of VAMP7. The mislocalization can be rescued by transfection with wild-type δ-adaptin but not by δ-adaptin containing mutations that abolish VAMP7 binding, despite in all cases intact AP3 being present and LAMP1 trafficking being rescued.
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Affiliation(s)
- Helen M Kent
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
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78
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Okayama M, Shitara A, Arakawa T, Tajima Y, Mizoguchi I, Takuma T. SNARE proteins are not excessive for the formation of post-Golgi SNARE complexes in HeLa cells. Mol Cell Biochem 2012; 366:159-68. [DOI: 10.1007/s11010-012-1293-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 03/17/2012] [Indexed: 11/24/2022]
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79
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Feng W, Liang T, Yu J, Zhou W, Zhang Y, Wu Z, Xu T. RAB-27 and its effector RBF-1 regulate the tethering and docking steps of DCV exocytosis in C. elegans. SCIENCE CHINA. LIFE SCIENCES 2012; 55:228-35. [PMID: 22527519 DOI: 10.1007/s11427-012-4296-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 01/18/2012] [Indexed: 10/28/2022]
Abstract
The molecular mechanisms by which dense core vesicles (DCVs) translocate, tether, dock and prime are poorly understood. In this study, Caenorhabditis elegans was used as a model organism to study the function of Rab proteins and their effectors in DCV exocytosis. RAB-27/AEX-6, but not RAB-3, was found to be required for peptide release from neurons. By analyzing the movement of DCVs approaching the plasma membrane using total internal reflection fluorescence microscopy, we demonstrated that RAB-27/AEX-6 is involved in the tethering of DCVs and that its effector rabphilin/RBF-1 is required for the initial tethering and subsequent stabilization by docking.
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Affiliation(s)
- WanJuan Feng
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
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80
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Canton J, Ndjamen B, Hatsuzawa K, Kima PE. Disruption of the fusion of Leishmania parasitophorous vacuoles with ER vesicles results in the control of the infection. Cell Microbiol 2012; 14:937-48. [PMID: 22309219 DOI: 10.1111/j.1462-5822.2012.01767.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Parasitophorous vacuoles (PV) that harbour Leishmania parasites acquire some characteristics from fusion with host cell vesicles. Recent studies have shown that PVs acquire and display resident endoplasmic reticulum (ER) molecules. We investigated the importance of ER molecules to PV biology by assessing the consequence of blocking the fusion of PVs with vesicles that originate from the early secretory pathway. This was achieved by targeting the N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) that mediate the fusion of early secretory vesicles. In the presence of dominant negative variants of sec22b or some of its known cognate partners, D12 and syntaxin 18, PVs failed to distend and harboured fewer parasites. These observations were confirmed in studies in which each of the SNAREs listed above including the intermediate compartment ER/Golgi SNARE, syntaxin 5, was knocked down. The knock-down of these SNARES had little or no measurable effect on the morphology of the ER or on activated secretion even though they resulted in a more significant reduction of PV size. Moreover, the knock-down of the ER/Golgi SNAREs resulted in significant reduction in parasite replication. Taken together, these studies provide further evidence that PVs acquire ER components by fusing with vesicles derived from the early secretory pathway; disruption of this interaction results in inhibition of the development of PVs as well as the limitation of parasite replication within infected cells.
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Affiliation(s)
- Johnathan Canton
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611, USA
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81
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Syntaxin 17 cycles between the ER and ERGIC and is required to maintain the architecture of ERGIC and Golgi. Biol Cell 2012; 103:333-50. [DOI: 10.1042/bc20110006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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82
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Jun Y, Ahn K. Tmp21, a novel MHC-I interacting protein, preferentially binds to Β2-microglobulin-free MHC-I heavy chains. BMB Rep 2011; 44:369-74. [PMID: 21699748 DOI: 10.5483/bmbrep.2011.44.6.369] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MHC-I molecules play a critical role in immune surveillance against viruses by presenting peptides to cytotoxic T lymphocytes. Although the mechanisms by which MHC-I molecules assemble and acquire peptides in the ER are well characterized, how MHC-I molecules traffic to the cell surface remains poorly understood. To identify novel proteins that regulate the intracellular transport of MHC-I molecules, MHC-I-interacting proteins were isolated by affinity purification, and their identity was determined by mass spectrometry. Among the identified MHC-I-associated proteins was Tmp21, the human ortholog of yeast Emp24p, which mediates the ER-Golgi trafficking of a subset of proteins. Here, we show that Tmp21 binds to human classical and non-classical MHC-I molecules. The Tmp21-MHC-I complex lacks Β(2)-microglobulin, and the number of the complexes is increased when free MHC-I heavy chains are more abundant. Taken together, these results suggest that Tmp21 is a novel protein that preferentially binds to Β(2)-microglobulin-free MHC-I heavy chains.
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Affiliation(s)
- Youngsoo Jun
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
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83
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Autophagosome precursor maturation requires homotypic fusion. Cell 2011; 146:303-17. [PMID: 21784250 PMCID: PMC3171170 DOI: 10.1016/j.cell.2011.06.023] [Citation(s) in RCA: 297] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 01/27/2011] [Accepted: 06/13/2011] [Indexed: 11/23/2022]
Abstract
Autophagy is a catabolic process in which lysosomes degrade intracytoplasmic contents transported in double-membraned autophagosomes. Autophagosomes are formed by the elongation and fusion of phagophores, which can be derived from preautophagosomal structures coming from the plasma membrane and other sites like the endoplasmic reticulum and mitochondria. The mechanisms by which preautophagosomal structures elongate their membranes and mature toward fully formed autophagosomes still remain unknown. Here, we show that the maturation of the early Atg16L1 precursors requires homotypic fusion, which is essential for subsequent autophagosome formation. Atg16L1 precursor homotypic fusion depends on the SNARE protein VAMP7 together with partner SNAREs. Atg16L1 precursor homotypic fusion is a critical event in the early phases of autophagy that couples membrane acquisition and autophagosome biogenesis, as this step regulates the size of the vesicles, which in turn appears to influence their subsequent maturation into LC3-positive autophagosomes.
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84
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Walter AM, Groffen AJ, Sørensen JB, Verhage M. Multiple Ca2+ sensors in secretion: teammates, competitors or autocrats? Trends Neurosci 2011; 34:487-97. [PMID: 21831459 DOI: 10.1016/j.tins.2011.07.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/21/2011] [Accepted: 07/05/2011] [Indexed: 12/25/2022]
Abstract
Regulated neurotransmitter secretion depends on Ca(2+) sensors, C2 domain proteins that associate with phospholipids and soluble N-ethylmaleimide-sensitive fusion attachment protein receptor (SNARE) complexes to trigger release upon Ca(2+) binding. Ca(2+) sensors are thought to prevent spontaneous fusion at rest (clamping) and to promote fusion upon Ca(2+) activation. At least eight, often coexpressed, Ca(2+) sensors have been identified in mammals. Accumulating evidence suggests that multiple Ca(2+) sensors interact, rather than work autonomously, to produce the complex secretory response observed in neurons and secretory cells. In this review, we present several working models to describe how different sensors might be arranged to mediate synchronous, asynchronous and spontaneous neurotransmitter release. We discuss the scenario that different Ca(2+) sensors typically act on one shared vesicle pool and compete for binding the multiple SNARE complexes that are likely to assemble at single vesicles, to exert both clamping and fusion-promoting functions.
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Affiliation(s)
- Alexander M Walter
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit Amsterdam and VU Medical Center, 1081 HV Amsterdam, The Netherlands
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85
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Sato M, Saegusa K, Sato K, Hara T, Harada A, Sato K. Caenorhabditis elegans SNAP-29 is required for organellar integrity of the endomembrane system and general exocytosis in intestinal epithelial cells. Mol Biol Cell 2011; 22:2579-87. [PMID: 21613542 PMCID: PMC3135482 DOI: 10.1091/mbc.e11-04-0279] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Caenorhabditis elegans SNAP-29 is required for the proper morphology and functions of the Golgi and endosomes and general exocytosis. It is generally accepted that soluble N-ethylmaleimide–sensitive factor attachment protein receptors mediate the docking and fusion of transport intermediates with target membranes. Our research identifies Caenorhabditis elegans homologue of synaptosomal-associated protein 29 (SNAP-29) as an essential regulator of membrane trafficking in polarized intestinal cells of living animals. We show that a depletion of SNAP-29 blocks yolk secretion and targeting of apical and basolateral plasma membrane proteins in the intestinal cells and results in a strong accumulation of small cargo-containing vesicles. The loss of SNAP-29 also blocks the transport of yolk receptor RME-2 to the plasma membrane in nonpolarized oocytes, indicating that its function is required in various cell types. SNAP-29 is essential for embryogenesis, animal growth, and viability. Functional fluorescent protein–tagged SNAP-29 mainly localizes to the plasma membrane and the late Golgi, although it also partially colocalizes with endosomal proteins. The loss of SNAP-29 leads to the vesiculation/fragmentation of the Golgi and endosomes, suggesting that SNAP-29 is involved in multiple transport pathways between the exocytic and endocytic organelles. These observations also suggest that organelles comprising the endomembrane system are highly dynamic structures based on the balance between membrane budding and fusion and that SNAP-29–mediated fusion is required to maintain proper organellar morphology and functions.
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Affiliation(s)
- Miyuki Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan
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86
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Grigoriev I, Yu KL, Martinez-Sanchez E, Serra-Marques A, Smal I, Meijering E, Demmers J, Peränen J, Pasterkamp RJ, van der Sluijs P, Hoogenraad CC, Akhmanova A. Rab6, Rab8, and MICAL3 cooperate in controlling docking and fusion of exocytotic carriers. Curr Biol 2011; 21:967-74. [PMID: 21596566 DOI: 10.1016/j.cub.2011.04.030] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Revised: 03/16/2011] [Accepted: 04/18/2011] [Indexed: 12/23/2022]
Abstract
Rab6 is a conserved small GTPase that localizes to the Golgi apparatus and cytoplasmic vesicles and controls transport and fusion of secretory carriers [1]. Another Rab implicated in trafficking from the trans-Golgi to the plasma membrane is Rab8 [2-5]. Here we show that Rab8A stably associates with exocytotic vesicles in a Rab6-dependent manner. Rab8A function is not needed for budding or motility of exocytotic carriers but is required for their docking and fusion. These processes also depend on the Rab6-interacting cortical factor ELKS [1], suggesting that Rab8A and ELKS act in the same pathway. We show that Rab8A and ELKS can be linked by MICAL3, a member of the MICAL family of flavoprotein monooxygenases [6]. Expression of a MICAL3 mutant with an inactive monooxygenase domain resulted in a strong accumulation of secretory vesicles that were docked at the cell cortex but failed to fuse with the plasma membrane, an effect that correlated with the strongly reduced mobility of MICAL3. We propose that the monooxygenase activity of MICAL3 is required to regulate its own turnover and the concomitant remodeling of vesicle-docking protein complexes in which it is engaged. Taken together, the results of our study illustrate cooperation of two Rab proteins in constitutive exocytosis and implicates a redox enzyme in this process.
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Affiliation(s)
- Ilya Grigoriev
- Department of Cell Biology, Erasmus Medical Center, 3000 CA Rotterdam, The Netherlands
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87
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Hirano AA, Brandstätter JH, Morgans CW, Brecha NC. SNAP25 expression in mammalian retinal horizontal cells. J Comp Neurol 2011; 519:972-88. [PMID: 21280047 DOI: 10.1002/cne.22562] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Horizontal cells mediate inhibitory feedforward and feedback lateral interactions in the outer retina at photoreceptor terminals and bipolar cell dendrites; however, the mechanisms that underlie synaptic transmission from mammalian horizontal cells are poorly understood. The localization of a vesicular γ-aminobutyric acid (GABA) transporter (VGAT) to horizontal cell processes in primate and rodent retinae suggested that mammalian horizontal cells release transmitter in a vesicular manner. Toward determining whether the molecular machinery for vesicular transmitter release is present in horizontal cells, we investigated the expression of SNAP25 (synaptosomal-associated protein of 25 kDa), a key SNARE protein, by immunocytochemistry with cell type-specific markers in the retinae of mouse, rat, rabbit, and monkey. Different commercial antibodies to SNAP25 were tested on vertical sections of retina. We report the robust expression of SNAP25 in both plexiform layers. Double labeling with SNAP25 and calbindin antibodies demonstrated that horizontal cell processes and their endings in photoreceptor triad synapses were strongly labeled for both proteins in mouse, rat, rabbit, and monkey retinae. Double labeling with parvalbumin antibodies in monkey retina verified SNAP25 immunoreactivity in all horizontal cells. Pre-embedding immunoelectron microscopy in rabbit retina confirmed expression of SNAP25 in lateral elements within photoreceptor triad synapses. The SNAP25 immunoreactivity in the plexiform layers and outer nuclear layer fell into at least three patterns depending on the antibody, suggesting a differential distribution of SNAP25 isoforms. The presence of SNAP25a and SNAP25b isoforms in mouse retina was established by reverse transcriptase-polymerase chain reaction. SNAP25 expression in mammalian horizontal cells along with other SNARE proteins is consistent with vesicular exocytosis.
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Affiliation(s)
- Arlene A Hirano
- Department of Neurobiology, David Geffen School of Medicine at the University of California-Los Angeles, Los Angeles, California 90095, USA.
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88
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Kang J, Bai Z, Zegarek MH, Grant BD, Lee J. Essential roles of snap-29 in C. elegans. Dev Biol 2011; 355:77-88. [PMID: 21545795 DOI: 10.1016/j.ydbio.2011.04.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 03/29/2011] [Accepted: 04/14/2011] [Indexed: 12/29/2022]
Abstract
SNARE domain proteins are key molecules mediating intracellular fusion events. SNAP25 family proteins are unique target-SNAREs possessing two SNARE domains. Here we report the genetic, molecular, and cell biological characterization of C. elegans SNAP-29. We found that snap-29 is an essential gene required throughout the life-cycle. Depletion of snap-29 by RNAi in adults results in sterility associated with endomitotic oocytes and pre-meiotic maturation of the oocytes. Many of the embryos that are produced are multinucleated, indicating a defect in embryonic cytokinesis. A profound defect in secretion by oocytes and early embryos in animals lacking SNAP-29 appears to be the underlying defect connecting these phenotypes. Further analysis revealed defects in basolateral and apical secretion by intestinal epithelial cells in animals lacking SNAP-29, indicating a broad requirement for this protein in the secretory pathway. A SNAP-29-GFP fusion protein was enriched on recycling endosomes, and loss of SNAP-29 disrupted recycling endosome morphology. Taken together these results suggest a requirement for SNAP-29 in the fusion of post-Golgi vesicles with the recycling endosome for cargo to reach the cell surface.
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Affiliation(s)
- Junsu Kang
- Research Center for Functional Cellulomics, School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
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89
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Schiel JA, Park K, Morphew MK, Reid E, Hoenger A, Prekeris R. Endocytic membrane fusion and buckling-induced microtubule severing mediate cell abscission. J Cell Sci 2011; 124:1411-24. [PMID: 21486954 DOI: 10.1242/jcs.081448] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cytokinesis and abscission are complicated events that involve changes in membrane transport and cytoskeleton organization. We have used the combination of time-lapse microscopy and correlative high-resolution 3D tomography to analyze the regulation and spatio-temporal remodeling of endosomes and microtubules during abscission. We show that abscission is driven by the formation of a secondary ingression within the intracellular bridge connecting two daughter cells. The initiation and expansion of this secondary ingression requires recycling endosome fusion with the furrow plasma membrane and nested central spindle microtubule severing. These changes in endosome fusion and microtubule reorganization result in increased intracellular bridge plasma membrane dynamics and abscission. Finally, we show that central spindle microtubule reorganization is driven by localized microtubule buckling and breaking, rather than by spastin-dependent severing. Our results provide a new mechanism for mediation and regulation of the abscission step of cytokinesis.
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Affiliation(s)
- John A Schiel
- Department of Cell and Developmental Biology, University of Colorado Denver, Aurora, CO 80045, USA
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90
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Wiśniewski JR, Zielinska DF, Mann M. Comparison of ultrafiltration units for proteomic and N-glycoproteomic analysis by the filter-aided sample preparation method. Anal Biochem 2011; 410:307-9. [DOI: 10.1016/j.ab.2010.12.004] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 12/03/2010] [Accepted: 12/03/2010] [Indexed: 11/24/2022]
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91
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Renna M, Schaffner C, Winslow AR, Menzies FM, Peden AA, Floto RA, Rubinsztein DC. Autophagic substrate clearance requires activity of the syntaxin-5 SNARE complex. J Cell Sci 2011; 124:469-82. [PMID: 21242315 PMCID: PMC3022001 DOI: 10.1242/jcs.076489] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2010] [Indexed: 12/17/2022] Open
Abstract
Autophagy is a lysosome-dependent cellular catabolic mechanism that mediates the turnover of intracellular organelles and long-lived proteins. Reduced autophagic activity has been shown to lead to the accumulation of misfolded proteins in neurons and might be involved in chronic neurodegenerative diseases. Here, we uncover an essential role for the syntaxin-5 SNARE complex in autophagy. Using genetic knockdown, we show that the syntaxin-5 SNARE complex regulates the later stages of autophagy after the initial formation of autophagosomes. This SNARE complex acts on autophagy by regulating ER-to-Golgi transport through the secretory pathway, which is essential for the activity of lysosomal proteases such as cathepsins. Depletion of syntaxin-5 complex components results in the accumulation of autophagosomes as a result of lysosomal dysfunction, leading to decreased degradation of autophagic substrates. Our findings provide a novel link between a fundamental process such as intracellular trafficking and human diseases that might be affected by defective biogenesis and/or homeostasis of the autophagosome-lysosome degradation system.
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Affiliation(s)
- Maurizio Renna
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - Catherine Schaffner
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - Ashley R. Winslow
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - Fiona M. Menzies
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - Andrew A. Peden
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of Cambridge, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - R. Andres Floto
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
| | - David C. Rubinsztein
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Wellcome/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0XY, UK
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92
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Bond LM, Peden AA, Kendrick-Jones J, Sellers JR, Buss F. Myosin VI and its binding partner optineurin are involved in secretory vesicle fusion at the plasma membrane. Mol Biol Cell 2011; 22:54-65. [PMID: 21148290 PMCID: PMC3016977 DOI: 10.1091/mbc.e10-06-0553] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 10/14/2010] [Accepted: 10/21/2010] [Indexed: 12/14/2022] Open
Abstract
During constitutive secretion, proteins synthesized at the endoplasmic reticulum (ER) are transported to the Golgi complex for processing and then to the plasma membrane for incorporation or extracellular release. This study uses a unique live-cell constitutive secretion assay to establish roles for the molecular motor myosin VI and its binding partner optineurin in discrete stages of secretion. Small interfering RNA-based knockdown of myosin VI causes an ER-to-Golgi transport delay, suggesting an unexpected function for myosin VI in the early secretory pathway. Depletion of myosin VI or optineurin does not affect the number of vesicles leaving the trans-Golgi network (TGN), indicating that these proteins do not function in TGN vesicle formation. However, myosin VI and optineurin colocalize with secretory vesicles at the plasma membrane. Furthermore, live-cell total internal reflection fluorescence microscopy demonstrates that myosin VI or optineurin depletion reduces the total number of vesicle fusion events at the plasma membrane and increases both the proportion of incomplete fusion events and the number of docked vesicles in this region. These results suggest a novel role for myosin VI and optineurin in regulation of fusion pores formed between secretory vesicles and the plasma membrane during the final stages of secretion.
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Affiliation(s)
- Lisa M. Bond
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Andrew A. Peden
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | | | - James R. Sellers
- Laboratory of Molecular Physiology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Folma Buss
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
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