151
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At the ends of their tethers! How coiled-coil proteins capture vesicles at the Golgi. Biochem Soc Trans 2017; 46:43-50. [PMID: 29273618 DOI: 10.1042/bst20170188] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 11/22/2017] [Accepted: 11/23/2017] [Indexed: 12/20/2022]
Abstract
Cells face a complex problem: how to transfer lipids and proteins between membrane compartments in an organized, timely fashion. Indeed, many thousands of membrane and secretory proteins must traffic out of the ER to different organelles to function, while others are retrieved from the plasma membrane having fulfilled their roles [Nat. Rev. Mol. Cell Biol. (2013) 14, 382-392]. This process is highly dynamic and failure to target cargo accurately leads to catastrophic consequences for the cell, as is clear from the numerous human diseases associated with defects in membrane trafficking [Int. J. Mol. Sci. (2013) 14, 18670-18681; Traffic (2000) 1, 836-851]. How then does the cell organize this enormous transfer of material in its crowded internal environment? And how specifically do vesicles carrying proteins and lipids recognize and fuse with the correct compartment?
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152
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Riedel F, Galindo A, Muschalik N, Munro S. The two TRAPP complexes of metazoans have distinct roles and act on different Rab GTPases. J Cell Biol 2017; 217:601-617. [PMID: 29273580 PMCID: PMC5800803 DOI: 10.1083/jcb.201705068] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 10/19/2017] [Accepted: 11/27/2017] [Indexed: 12/03/2022] Open
Abstract
In yeast, the TRAPP complexes activate Rab1 with TRAPPII also activating Rab11, but less is known about the two TRAPPs in metazoans. Riedel et al. show that in Drosophila melanogaster, TRAPPIII is an essential Rab1 activator, and TRAPPII activates Rab1 and Rab11 and becomes essential when an unrelated Rab11 activator is deleted. Originally identified in yeast, transport protein particle (TRAPP) complexes are Rab GTPase exchange factors that share a core set of subunits. TRAPPs were initially found to act on Ypt1, the yeast orthologue of Rab1, but recent studies have found that yeast TRAPPII can also activate the Rab11 orthologues Ypt31/32. Mammals have two TRAPP complexes, but their role is less clear, and they contain subunits that are not found in the yeast complexes but are essential for cell growth. To investigate TRAPP function in metazoans, we show that Drosophila melanogaster have two TRAPP complexes similar to those in mammals and that both activate Rab1, whereas one, TRAPPII, also activates Rab11. TRAPPII is not essential but becomes so in the absence of the gene parcas that encodes the Drosophila orthologue of the SH3BP5 family of Rab11 guanine nucleotide exchange factors (GEFs). Thus, in metazoans, Rab1 activation requires TRAPP subunits not found in yeast, and Rab11 activation is shared by TRAPPII and an unrelated GEF that is metazoan specific.
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Affiliation(s)
- Falko Riedel
- Medical Research Council Laboratory of Molecular Biology, Cambridge, England, UK
| | - Antonio Galindo
- Medical Research Council Laboratory of Molecular Biology, Cambridge, England, UK
| | - Nadine Muschalik
- Medical Research Council Laboratory of Molecular Biology, Cambridge, England, UK
| | - Sean Munro
- Medical Research Council Laboratory of Molecular Biology, Cambridge, England, UK
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153
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Kaczmarek B, Verbavatz JM, Jackson CL. GBF1 and Arf1 function in vesicular trafficking, lipid homoeostasis and organelle dynamics. Biol Cell 2017; 109:391-399. [PMID: 28985001 DOI: 10.1111/boc.201700042] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/22/2017] [Accepted: 09/25/2017] [Indexed: 01/07/2023]
Abstract
The ADP-ribosylation factor (Arf) small G proteins act as molecular switches to coordinate multiple downstream pathways that regulate membrane dynamics. Their activation is spatially and temporally controlled by the guanine nucleotide exchange factors (GEFs). Members of the evolutionarily conserved GBF/Gea family of Arf GEFs are well known for their roles in formation of coat protein complex I (COPI) vesicles, essential for maintaining the structure and function of the Golgi apparatus. However, studies over the past 10 years have found new functions for these GEFs, along with their substrate Arf1, in lipid droplet metabolism, clathrin-independent endocytosis, signalling at the plasma membrane, mitochondrial dynamics and transport along microtubules. Here, we describe these different functions, focussing in particular on the emerging theme of GFB1 and Arf1 regulation of organelle movement on microtubules.
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Affiliation(s)
- Beata Kaczmarek
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
| | - Jean-Marc Verbavatz
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
| | - Catherine L Jackson
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
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154
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Nagy P, Szatmári Z, Sándor GO, Lippai M, Hegedűs K, Juhász G. Drosophila Atg16 promotes enteroendocrine cell differentiation via regulation of intestinal Slit/Robo signaling. Development 2017; 144:3990-4001. [PMID: 28982685 DOI: 10.1242/dev.147033] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 09/25/2017] [Indexed: 12/22/2022]
Abstract
Genetic variations of Atg16l1, Slit2 and Rab19 predispose to the development of inflammatory bowel disease (IBD), but the relationship between these mutations is unclear. Here we show that in Drosophila guts lacking the WD40 domain of Atg16, pre-enteroendocrine (pre-EE) cells accumulate that fail to differentiate into properly functioning secretory EE cells. Mechanistically, loss of Atg16 or its binding partner Rab19 impairs Slit production, which normally inhibits EE cell generation by activating Robo signaling in stem cells. Importantly, loss of Atg16 or decreased Slit/Robo signaling triggers an intestinal inflammatory response. Surprisingly, analysis of Rab19 and domain-specific Atg16 mutants indicates that their stem cell niche regulatory function is independent of autophagy. Our study reveals how mutations in these different genes may contribute to IBD.
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Affiliation(s)
- Péter Nagy
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest, H-1117 Hungary
| | - Zsuzsanna Szatmári
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest, H-1117 Hungary
| | - Gyöngyvér O Sándor
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest, H-1117 Hungary
| | - Mónika Lippai
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest, H-1117 Hungary
| | - Krisztina Hegedűs
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest, H-1117 Hungary
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Pázmány s. 1/C, Budapest, H-1117 Hungary
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, Szeged, H-6726 Hungary
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155
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Csizmadia T, Lőrincz P, Hegedűs K, Széplaki S, Lőw P, Juhász G. Molecular mechanisms of developmentally programmed crinophagy in Drosophila. J Cell Biol 2017; 217:361-374. [PMID: 29066608 PMCID: PMC5748974 DOI: 10.1083/jcb.201702145] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 08/09/2017] [Accepted: 09/22/2017] [Indexed: 12/20/2022] Open
Abstract
During crinophagy, secretory granules directly fuse with lysosomes to degrade their contents. Csizmadia et al. show that excess glue granules in Drosophila salivary glands are degraded by crinophagy at the onset of metamorphosis. Glue granule–lysosome fusion requires the HOPS tether, Rab2, Rab7, and a SNARE complex consisting of Syntaxin 13, Snap29, and Vamp7. At the onset of metamorphosis, Drosophila salivary gland cells undergo a burst of glue granule secretion to attach the forming pupa to a solid surface. Here, we show that excess granules evading exocytosis are degraded via direct fusion with lysosomes, a secretory granule-specific autophagic process known as crinophagy. We find that the tethering complex HOPS (homotypic fusion and protein sorting); the small GTPases Rab2, Rab7, and its effector, PLEKHM1; and a SNAP receptor complex consisting of Syntaxin 13, Snap29, and Vamp7 are all required for the fusion of secretory granules with lysosomes. Proper glue degradation within lysosomes also requires the Uvrag-containing Vps34 lipid kinase complex and the v-ATPase proton pump, whereas Atg genes involved in macroautophagy are dispensable for crinophagy. Our work establishes the molecular mechanism of developmentally programmed crinophagy in Drosophila and paves the way for analyzing this process in metazoans.
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Affiliation(s)
- Tamás Csizmadia
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Péter Lőrincz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Krisztina Hegedűs
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Szilvia Széplaki
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Péter Lőw
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary .,Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
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156
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Cattin-Ortolá J, Topalidou I, Dosey A, Merz AJ, Ailion M. The dense-core vesicle maturation protein CCCP-1 binds RAB-2 and membranes through its C-terminal domain. Traffic 2017; 18:720-732. [PMID: 28755404 DOI: 10.1111/tra.12507] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 07/26/2017] [Accepted: 07/26/2017] [Indexed: 12/18/2022]
Abstract
Dense-core vesicles (DCVs) are secretory organelles that store and release modulatory neurotransmitters from neurons and endocrine cells. Recently, the conserved coiled-coil protein CCCP-1 was identified as a component of the DCV biogenesis pathway in the nematode Caenorhabditis elegans. CCCP-1 binds the small GTPase RAB-2 and colocalizes with it at the trans-Golgi. Here, we report a structure-function analysis of CCCP-1 to identify domains of the protein important for its localization, binding to RAB-2, and function in DCV biogenesis. We find that the CCCP-1 C-terminal domain (CC3) has multiple activities. CC3 is necessary and sufficient for CCCP-1 localization and for binding to RAB-2, and is required for the function of CCCP-1 in DCV biogenesis. In addition, CCCP-1 binds membranes directly through its CC3 domain, indicating that CC3 may comprise a previously uncharacterized lipid-binding motif. We conclude that CCCP-1 is a coiled-coil protein that binds an activated Rab and localizes to the Golgi via its C-terminus, properties similar to members of the golgin family of proteins. CCCP-1 also shares biophysical features with golgins; it has an elongated shape and forms oligomers.
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Affiliation(s)
| | - Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle, Washington
| | - Annie Dosey
- Department of Biochemistry, University of Washington, Seattle, Washington
| | - Alexey J Merz
- Department of Biochemistry, University of Washington, Seattle, Washington.,Department of Physiology and Biophysics, University of Washington, Seattle, Washington
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle, Washington
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157
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Identification of Rab18 as an Essential Host Factor for BK Polyomavirus Infection Using a Whole-Genome RNA Interference Screen. mSphere 2017; 2:mSphere00291-17. [PMID: 28815213 PMCID: PMC5555678 DOI: 10.1128/mspheredirect.00291-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 07/12/2017] [Indexed: 11/20/2022] Open
Abstract
Polyomaviruses bind to a group of specific gangliosides on the plasma membrane of the cell prior to being endocytosed. They then follow a retrograde trafficking pathway to reach the endoplasmic reticulum (ER). The viruses begin to disassemble in the ER and then exit the ER and move to the nucleus. However, the details of intracellular trafficking between the endosome and the ER are largely unknown. By implementing a whole human genome small interfering RNA screen, we identified Rab18, syntaxin 18, and the NRZ complex as key components in endosome-ER trafficking of the human polyomavirus BKPyV. These results serve to further elucidate the route BKPyV takes from outside the cell to its site of replication in the nucleus. BK polyomavirus (BKPyV) is a human pathogen first isolated in 1971. BKPyV infection is ubiquitous in the human population, with over 80% of adults worldwide being seropositive for BKPyV. BKPyV infection is usually asymptomatic; however, BKPyV reactivation in immunosuppressed transplant patients causes two diseases, polyomavirus-associated nephropathy and hemorrhagic cystitis. To establish a successful infection in host cells, BKPyV must travel in retrograde transport vesicles to reach the nucleus. To make this happen, BKPyV requires the cooperation of host cell proteins. To further identify host factors associated with BKPyV entry and intracellular trafficking, we performed a whole-genome small interfering RNA screen on BKPyV infection of primary human renal proximal tubule epithelial cells. The results revealed the importance of Ras-related protein Rab18 and syntaxin 18 for BKPyV infection. Our subsequent experiments implicated additional factors that interact with this pathway and suggest a more detailed model of the intracellular trafficking process, indicating that BKPyV reaches the endoplasmic reticulum (ER) lumen through a retrograde transport pathway between the late endosome and the ER. IMPORTANCE Polyomaviruses bind to a group of specific gangliosides on the plasma membrane of the cell prior to being endocytosed. They then follow a retrograde trafficking pathway to reach the endoplasmic reticulum (ER). The viruses begin to disassemble in the ER and then exit the ER and move to the nucleus. However, the details of intracellular trafficking between the endosome and the ER are largely unknown. By implementing a whole human genome small interfering RNA screen, we identified Rab18, syntaxin 18, and the NRZ complex as key components in endosome-ER trafficking of the human polyomavirus BKPyV. These results serve to further elucidate the route BKPyV takes from outside the cell to its site of replication in the nucleus.
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158
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Pylypenko O, Hammich H, Yu IM, Houdusse A. Rab GTPases and their interacting protein partners: Structural insights into Rab functional diversity. Small GTPases 2017. [PMID: 28632484 PMCID: PMC5902227 DOI: 10.1080/21541248.2017.1336191] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rab molecular switches are key players in defining membrane identity and regulating intracellular trafficking events in eukaryotic cells. In spite of their global structural similarity, Rab-family members acquired particular features that allow them to perform specific cellular functions. The overall fold and local sequence conservations enable them to utilize a common machinery for prenylation and recycling; while individual Rab structural differences determine interactions with specific partners such as GEFs, GAPs and effector proteins. These interactions orchestrate the spatiotemporal regulation of Rab localization and their turning ON and OFF, leading to tightly controlled Rab-specific functionalities such as membrane composition modifications, recruitment of molecular motors for intracellular trafficking, or recruitment of scaffold proteins that mediate interactions with downstream partners, as well as actin cytoskeleton regulation. In this review we summarize structural information on Rab GTPases and their complexes with protein partners in the context of partner binding specificity and functional outcomes of their interactions in the cell.
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Affiliation(s)
- Olena Pylypenko
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
| | - Hussein Hammich
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France.,b Sorbonne Universités , UPMC Univ Paris 06, Sorbonne Universités, IFD , Paris , France
| | - I-Mei Yu
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
| | - Anne Houdusse
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
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159
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Golgi trafficking defects in postnatal microcephaly: The evidence for “Golgipathies”. Prog Neurobiol 2017; 153:46-63. [DOI: 10.1016/j.pneurobio.2017.03.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 02/22/2017] [Accepted: 03/29/2017] [Indexed: 12/17/2022]
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160
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Thomason PA, King JS, Insall RH. Mroh1, a lysosomal regulator localized by WASH-generated actin. J Cell Sci 2017; 130:1785-1795. [PMID: 28424231 PMCID: PMC5450189 DOI: 10.1242/jcs.197210] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 03/29/2017] [Indexed: 02/06/2023] Open
Abstract
The steps leading to constitutive exocytosis are poorly understood. In Dictyostelium WASH complex mutants, exocytosis is blocked, so cells that take up fluorescent dextran from the medium retain it and remain fluorescent. Here, we establish a FACS-based method to select cells that retain fluorescent dextran, allowing identification of mutants with disrupted exocytosis. Screening a pool of random mutants identified members of the WASH complex, as expected, and multiple mutants in the conserved HEAT-repeat-containing protein Mroh1. In mroh1 mutants, endosomes develop normally until the stage where lysosomes neutralize to postlysosomes, but thereafter the WASH complex is recycled inefficiently, and subsequent exocytosis is substantially delayed. Mroh1 protein localizes to lysosomes in mammalian and Dictyostelium cells. In Dictyostelium, it accumulates on lysosomes as they mature and is removed, together with the WASH complex, shortly before the postlysosomes are exocytosed. WASH-generated F-actin is required for correct subcellular localization; in WASH complex mutants, and immediately after latrunculin treatment, Mroh1 relocalizes from the cytoplasm to small vesicles. Thus, Mroh1 is involved in a late and hitherto undefined actin-dependent step in exocytosis.
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Affiliation(s)
- Peter A Thomason
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | - Jason S King
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
| | - Robert H Insall
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK
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161
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Lőrincz P, Tóth S, Benkő P, Lakatos Z, Boda A, Glatz G, Zobel M, Bisi S, Hegedűs K, Takáts S, Scita G, Juhász G. Rab2 promotes autophagic and endocytic lysosomal degradation. J Cell Biol 2017; 216:1937-1947. [PMID: 28483915 PMCID: PMC5496615 DOI: 10.1083/jcb.201611027] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 02/24/2017] [Accepted: 04/21/2017] [Indexed: 11/22/2022] Open
Abstract
Rab7 promotes fusion of autophagosomes and late endosomes with lysosomes. Lőrincz et al. show that Rab2 is critical for the delivery of autophagic and endocytic cargo to lysosomes and for their degradation, and that it promotes autophagosome–lysosome fusion. The results suggest Rab2 and Rab7 coordinately promote autophagic and endosomal degradation and lysosome function. Rab7 promotes fusion of autophagosomes and late endosomes with lysosomes in yeast and metazoan cells, acting together with its effector, the tethering complex HOPS. Here we show that another small GTPase, Rab2, is also required for autophagosome and endosome maturation and proper lysosome function in Drosophila melanogaster. We demonstrate that Rab2 binds to HOPS, and that its active, GTP-locked form associates with autolysosomes. Importantly, expression of active Rab2 promotes autolysosomal fusions unlike that of GTP-locked Rab7, suggesting that its amount is normally rate limiting. We also demonstrate that RAB2A is required for autophagosome clearance in human breast cancer cells. In conclusion, we identify Rab2 as a key factor for autophagic and endocytic cargo delivery to and degradation in lysosomes.
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Affiliation(s)
- Péter Lőrincz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Sarolta Tóth
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Péter Benkő
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Zsolt Lakatos
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Attila Boda
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Gábor Glatz
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged H-6726, Hungary
| | - Martina Zobel
- FIRC (Fondazione Italiana per la Ricerca sul Cancro) Institute of Molecular Oncology (IFOM), Milan 20139, Italy
| | - Sara Bisi
- FIRC (Fondazione Italiana per la Ricerca sul Cancro) Institute of Molecular Oncology (IFOM), Milan 20139, Italy
| | - Krisztina Hegedűs
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Szabolcs Takáts
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest H-1117, Hungary
| | - Giorgio Scita
- FIRC (Fondazione Italiana per la Ricerca sul Cancro) Institute of Molecular Oncology (IFOM), Milan 20139, Italy.,Department of Oncology and Hemato-Oncology, School of Medicine, University of Milan, Milan 20122, Italy
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest H-1117, Hungary .,Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged H-6726, Hungary
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162
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Abstract
ADP-ribosylation factors (Arfs) and ADP-ribosylation factor-like proteins (Arls) are highly conserved small GTPases that function as main regulators of vesicular trafficking and cytoskeletal reorganization. Arl1, the first identified member of the large Arl family, is an important regulator of Golgi complex structure and function in organisms ranging from yeast to mammals. Together with its effectors, Arl1 has been shown to be involved in several cellular processes, including endosomal trans-Golgi network and secretory trafficking, lipid droplet and salivary granule formation, innate immunity and neuronal development, stress tolerance, as well as the response of the unfolded protein. In this Commentary, we provide a comprehensive summary of the Arl1-dependent cellular functions and a detailed characterization of several Arl1 effectors. We propose that involvement of Arl1 in these diverse cellular functions reflects the fact that Arl1 is activated at several late-Golgi sites, corresponding to specific molecular complexes that respond to and integrate multiple signals. We also provide insight into how the GTP-GDP cycle of Arl1 is regulated, and highlight a newly discovered mechanism that controls the sophisticated regulation of Arl1 activity at the Golgi complex.
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Affiliation(s)
- Chia-Jung Yu
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Linkou, Tao-Yuan 33302, Taiwan.,Department of Thoracic Medicine, Chang Gung Memorial Hospital, Linkou, Tao-Yuan 33305, Taiwan
| | - Fang-Jen S Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan .,Department of Medical Research, National Taiwan University Hospital, Taipei 10002, Taiwan
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163
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Mallik B, Dwivedi MK, Mushtaq Z, Kumari M, Verma PK, Kumar V. Regulation of neuromuscular junction organization by Rab2 and its effector ICA69 in Drosophila. Development 2017; 144:2032-2044. [PMID: 28455372 DOI: 10.1242/dev.145920] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 04/19/2017] [Indexed: 12/31/2022]
Abstract
The mechanisms underlying synaptic differentiation, which involves neuronal membrane and cytoskeletal remodeling, are not completely understood. We performed a targeted RNAi-mediated screen of Drosophila BAR-domain proteins and identified islet cell autoantigen 69 kDa (ICA69) as one of the key regulators of morphological differentiation of the larval neuromuscular junction (NMJ). We show that Drosophila ICA69 colocalizes with α-Spectrin at the NMJ. The conserved N-BAR domain of ICA69 deforms liposomes in vitro Full-length ICA69 and the ICAC but not the N-BAR domain of ICA69 induce filopodia in cultured cells. Consistent with its cytoskeleton regulatory role, ICA69 mutants show reduced α-Spectrin immunoreactivity at the larval NMJ. Manipulating levels of ICA69 or its interactor PICK1 alters the synaptic level of ionotropic glutamate receptors (iGluRs). Moreover, reducing PICK1 or Rab2 levels phenocopies ICA69 mutation. Interestingly, Rab2 regulates not only synaptic iGluR but also ICA69 levels. Thus, our data suggest that: (1) ICA69 regulates NMJ organization through a pathway that involves PICK1 and Rab2, and (2) Rab2 functions genetically upstream of ICA69 and regulates NMJ organization and targeting/retention of iGluRs by regulating ICA69 levels.
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Affiliation(s)
- Bhagaban Mallik
- Department of Biological Sciences, AB-3, Indian Institute of Science Education and Research, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Manish Kumar Dwivedi
- Department of Biological Sciences, AB-3, Indian Institute of Science Education and Research, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Zeeshan Mushtaq
- Department of Biological Sciences, AB-3, Indian Institute of Science Education and Research, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Manisha Kumari
- National Institute of Plant Genome Research (NIPGR), New Delhi 110067, India
| | - Praveen Kumar Verma
- National Institute of Plant Genome Research (NIPGR), New Delhi 110067, India
| | - Vimlesh Kumar
- Department of Biological Sciences, AB-3, Indian Institute of Science Education and Research, Bhauri, Bhopal, Madhya Pradesh 462066, India
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164
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Lanzetti L, Di Fiore PP. Behind the Scenes: Endo/Exocytosis in the Acquisition of Metastatic Traits. Cancer Res 2017; 77:1813-1817. [PMID: 28373181 DOI: 10.1158/0008-5472.can-16-3403] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 01/01/2017] [Indexed: 11/16/2022]
Abstract
Alterations of endo/exocytic proteins have long been associated with malignant transformation, and genes encoding membrane trafficking proteins have been identified as bona fide drivers of tumorigenesis. Focusing on the mechanisms underlying the impact of endo/exocytic proteins in cancer, a scenario emerges in which altered trafficking routes/networks appear to be preferentially involved in the acquisition of prometastatic traits. This involvement in metastasis frequently occurs through the integration of programs leading to migratory/invasive phenotypes, survival and resistance to environmental stresses, epithelial-to-mesenchymal transition, and the emergence of cancer stem cells. These findings might have important implications in the clinical setting for the development of metastasis-specific drugs and for patient stratification to optimize the use of available therapies. Cancer Res; 77(8); 1813-7. ©2017 AACR.
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Affiliation(s)
- Letizia Lanzetti
- Membrane Trafficking Laboratory at Candiolo Cancer Institute - FPO, IRCCS, Candiolo, Italy. .,Department of Oncology, University of Turin Medical School, Turin, Italy
| | - Pier Paolo Di Fiore
- IFOM, The FIRC Institute for Molecular Oncology Foundation, Milan, Italy. .,DIPO, Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy.,Molecular Medicine Program, European Institute of Oncology, Milan, Italy
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165
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Neefjes J, Jongsma MML, Berlin I. Stop or Go? Endosome Positioning in the Establishment of Compartment Architecture, Dynamics, and Function. Trends Cell Biol 2017; 27:580-594. [PMID: 28363667 DOI: 10.1016/j.tcb.2017.03.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/03/2017] [Accepted: 03/06/2017] [Indexed: 02/03/2023]
Abstract
The endosomal system constitutes a key negotiator between the environment of a cell and its internal affairs. Comprised of a complex membranous network, wherein each vesicle can in principle move autonomously throughout the cell, the endosomal system operates as a coherent unit to optimally face external challenges and maintain homeostasis. Our appreciation of how individual endosomes are controlled in time and space to best serve their collective purpose has evolved dramatically in recent years. In light of these efforts, the endoplasmic reticulum (ER) - with its expanse of membranes permeating the cytoplasmic space - has emerged as a potent spatiotemporal organizer of endosome biology. We review the latest advances in our understanding of the mechanisms underpinning endosomal transport and positioning, with emphasis on the contributions from the ER, and offer a perspective on how the interplay between these aspects shapes the architecture and dynamics of the endosomal system and drives its myriad cellular functions.
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Affiliation(s)
- Jacques Neefjes
- Department of Chemical Immunology, Leiden University Medical Center (LUMC), Einthovenweg 20, 2333 ZC Leiden, The Netherlands
| | - Marlieke M L Jongsma
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory, Academic Medical Center (AMC)/Universiteit van Amsterdam (UvA), Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands
| | - Ilana Berlin
- Department of Chemical Immunology, Leiden University Medical Center (LUMC), Einthovenweg 20, 2333 ZC Leiden, The Netherlands.
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166
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Caviglia S, Flores-Benitez D, Lattner J, Luschnig S, Brankatschk M. Rabs on the fly: Functions of Rab GTPases during development. Small GTPases 2017; 10:89-98. [PMID: 28118081 PMCID: PMC6380344 DOI: 10.1080/21541248.2017.1279725] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The organization of intracellular transport processes is adapted specifically to different cell types, developmental stages, and physiologic requirements. Some protein traffic routes are universal to all cells and constitutively active, while other routes are cell-type specific, transient, and induced under particular conditions only. Small GTPases of the Rab (Ras related in brain) subfamily are conserved across eukaryotes and regulate most intracellular transit pathways. The complete sets of Rab proteins have been identified in model organisms, and molecular principles underlying Rab functions have been uncovered. Rabs provide intracellular landmarks that define intracellular transport sequences. Nevertheless, it remains a challenge to systematically map the subcellular distribution of all Rabs and their functional interrelations. This task requires novel tools to precisely describe and manipulate the Rab machinery in vivo. Here we discuss recent findings about Rab roles during development and we consider novel approaches to investigate Rab functions in vivo.
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Affiliation(s)
- Sara Caviglia
- a Danish Stem Cell Center (DanStem), University of Copenhagen , Copenhagen , Denmark.,c Institute of Molecular Life Sciences and Ph.D. Program in Molecular Life Sciences, University of Zurich , Zurich , Switzerland
| | - David Flores-Benitez
- b Max Planck Institute for Cell Biology and Genetics (MPI-CBG) , Dresden , Germany
| | - Johanna Lattner
- b Max Planck Institute for Cell Biology and Genetics (MPI-CBG) , Dresden , Germany
| | - Stefan Luschnig
- c Institute of Molecular Life Sciences and Ph.D. Program in Molecular Life Sciences, University of Zurich , Zurich , Switzerland.,d Institute of Neurobiology and Cluster of Excellence Cells-in-Motion (EXC 1003 - CiM), University of Münster , Münster , Germany
| | - Marko Brankatschk
- e The Biotechnological Center of the TU Dresden (BIOTEC) , Dresden , Germany
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167
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Reggiori F, Ungermann C. Autophagosome Maturation and Fusion. J Mol Biol 2017; 429:486-496. [DOI: 10.1016/j.jmb.2017.01.002] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 01/03/2017] [Accepted: 01/04/2017] [Indexed: 02/07/2023]
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168
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Kajiho H, Kajiho Y, Scita G. Harnessing membrane trafficking to promote cancer spreading and invasion: The case of RAB2A. Small GTPases 2017; 9:304-309. [PMID: 28060560 DOI: 10.1080/21541248.2016.1223990] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
How cancer disseminates and metastasizes remains an outstanding open question. Emerging evidence indicates that membrane trafficking is frequently harnessed by tumors of epithelial origin to acquire a mesenchymal program of invasiveness. However, the critical molecular hubs used by cancer cells this context have only began to be elucidated. Here, we discussed the results of a recent phenotypic screening that led to the identification of the small GTPase RAB2A, not previously involved in cancer dissemination, as pivotal for the acquisition of pericellular proteolysis, cell dissemination and distant metastatic spreading of human breast cancer. At the cellular levels, RAB2A controls both canonical polarized Golgi-to-Plasma membrane trafficking of the junctional protein E-cadherin, and post-endocytic trafficking of the membrane-bound metalloprotease, MT1-MMP. This finding reveals an unexpected plasticity in the control of diverse trafficking routes exerted by RAB2A through canonical (Golgi stacking) and non-canonical (late endosome recycling) functional interactions, contributing to break established membrane trafficking dogma on the rigorous molecular distinction between polarized Golgi and post endocytic routes. Finally, they suggest that epithelial cancers may specifically select for those molecules that enable them to control multiple trafficking routes, in turn essential for the regulation of activities necessary for acquisition of mesenchymal traits.
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Affiliation(s)
- Hiroaki Kajiho
- a IFOM, the FIRC Institute of Molecular Oncology , Milan , Italy.,b Division of Membrane Dynamics, Department of Physiology and Cell Biology , Kobe University Graduate School of Medicine Kobe City , Hyogo , Japan
| | - Yuko Kajiho
- a IFOM, the FIRC Institute of Molecular Oncology , Milan , Italy.,c Department of Pediatrics , Graduate School of Medicine, The University of Tokyo , Bunkyo-ku, Tokyo , Japan
| | - Giorgio Scita
- a IFOM, the FIRC Institute of Molecular Oncology , Milan , Italy.,d Department of Oncology and Hemato-Oncology , DIPO, Università degli Studi di Milano , Milan , Italy
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169
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Fujita N, Huang W, Lin TH, Groulx JF, Jean S, Nguyen J, Kuchitsu Y, Koyama-Honda I, Mizushima N, Fukuda M, Kiger AA. Genetic screen in Drosophila muscle identifies autophagy-mediated T-tubule remodeling and a Rab2 role in autophagy. eLife 2017; 6. [PMID: 28063257 PMCID: PMC5249261 DOI: 10.7554/elife.23367] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/17/2016] [Indexed: 01/04/2023] Open
Abstract
Transverse (T)-tubules make-up a specialized network of tubulated muscle cell membranes involved in excitation-contraction coupling for power of contraction. Little is known about how T-tubules maintain highly organized structures and contacts throughout the contractile system despite the ongoing muscle remodeling that occurs with muscle atrophy, damage and aging. We uncovered an essential role for autophagy in T-tubule remodeling with genetic screens of a developmentally regulated remodeling program in Drosophila abdominal muscles. Here, we show that autophagy is both upregulated with and required for progression through T-tubule disassembly stages. Along with known mediators of autophagosome-lysosome fusion, our screens uncovered an unexpected shared role for Rab2 with a broadly conserved function in autophagic clearance. Rab2 localizes to autophagosomes and binds to HOPS complex members, suggesting a direct role in autophagosome tethering/fusion. Together, the high membrane flux with muscle remodeling permits unprecedented analysis both of T-tubule dynamics and fundamental trafficking mechanisms. DOI:http://dx.doi.org/10.7554/eLife.23367.001
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Affiliation(s)
- Naonobu Fujita
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States.,Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Wilson Huang
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Tzu-Han Lin
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Jean-Francois Groulx
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Steve Jean
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Jen Nguyen
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Yoshihiko Kuchitsu
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Ikuko Koyama-Honda
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Amy A Kiger
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
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170
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Li C, Luo X, Zhao S, Siu GK, Liang Y, Chan HC, Satoh A, Yu SS. COPI-TRAPPII activates Rab18 and regulates its lipid droplet association. EMBO J 2016; 36:441-457. [PMID: 28003315 DOI: 10.15252/embj.201694866] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 11/11/2016] [Accepted: 11/16/2016] [Indexed: 11/09/2022] Open
Abstract
The transport protein particle (TRAPP) was initially identified as a vesicle tethering factor in yeast and as a guanine nucleotide exchange factor (GEF) for Ypt1/Rab1. In mammals, structures and functions of various TRAPP complexes are beginning to be understood. We found that mammalian TRAPPII was a GEF for both Rab18 and Rab1. Inactivation of TRAPPII-specific subunits by various methods including siRNA depletion and CRISPR-Cas9-mediated deletion reduced lipolysis and resulted in aberrantly large lipid droplets. Recruitment of Rab18 onto lipid droplet (LD) surface was defective in TRAPPII-deleted cells, but the localization of Rab1 on Golgi was not affected. COPI regulates LD homeostasis. We found that the previously documented interaction between TRAPPII and COPI was also required for the recruitment of Rab18 to the LD We hypothesize that the interaction between COPI and TRAPPII helps bring TRAPPII onto LD surface, and TRAPPII, in turn, activates Rab18 and recruits it on the LD surface to facilitate its functions in LD homeostasis.
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Affiliation(s)
- Chunman Li
- Department of Anatomy, Histology and Developmental Biology, School of Basic Medical Sciences, Health Science Centre, Shenzhen University, Shenzhen, China.,School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Xiaomin Luo
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Shan Zhao
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Gavin Ky Siu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Yongheng Liang
- Key Laboratory of Agricultural Environmental Microbiology of MOA, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Hsiao Chang Chan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China.,Epithelial Cell Biology Research Centre, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Ayano Satoh
- The Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
| | - Sidney Sb Yu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China .,Epithelial Cell Biology Research Centre, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
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171
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Thomas LL, Fromme JC. GTPase cross talk regulates TRAPPII activation of Rab11 homologues during vesicle biogenesis. J Cell Biol 2016; 215:499-513. [PMID: 27872253 PMCID: PMC5119942 DOI: 10.1083/jcb.201608123] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/07/2016] [Accepted: 10/14/2016] [Indexed: 11/22/2022] Open
Abstract
Rab GTPases control vesicle formation and transport, but which proteins are important for their regulation is incompletely understood. Thomas and Fromme provide definitive evidence that TRAPPII is a GEF for the yeast Rab11 homologues Ypt31/32 and implicate the GTPase Arf1 in TRAPPII recruitment, suggesting that a bidirectional cross talk mechanism drives vesicle biogenesis. Rab guanosine triphosphatases (GTPases) control cellular trafficking pathways by regulating vesicle formation, transport, and tethering. Rab11 and its paralogs regulate multiple secretory and endocytic recycling pathways, yet the guanine nucleotide exchange factor (GEF) that activates Rab11 in most eukaryotic cells is unresolved. The large multisubunit transport protein particle (TRAPP) II complex has been proposed to act as a GEF for Rab11 based on genetic evidence, but conflicting biochemical experiments have created uncertainty regarding Rab11 activation. Using physiological Rab-GEF reconstitution reactions, we now provide definitive evidence that TRAPPII is a bona fide GEF for the yeast Rab11 homologues Ypt31/32. We also uncover a direct role for Arf1, a distinct GTPase, in recruiting TRAPPII to anionic membranes. Given the known role of Ypt31/32 in stimulating activation of Arf1, a bidirectional cross talk mechanism appears to drive biogenesis of secretory and endocytic recycling vesicles. By coordinating simultaneous activation of two essential GTPase pathways, this mechanism ensures recruitment of the complete set of effectors needed for vesicle formation, transport, and tethering.
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Affiliation(s)
- Laura L Thomas
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - J Christopher Fromme
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
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172
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Progida C, Bakke O. Bidirectional traffic between the Golgi and the endosomes - machineries and regulation. J Cell Sci 2016; 129:3971-3982. [PMID: 27802132 DOI: 10.1242/jcs.185702] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The bidirectional transport between the Golgi complex and the endocytic pathway has to be finely regulated in order to ensure the proper delivery of newly synthetized lysosomal enzymes and the return of sorting receptors from degradative compartments. The high complexity of these routes has led to experimental difficulties in properly dissecting and separating the different pathways. As a consequence, several models have been proposed during the past decades. However, recent advances in our understanding of endosomal dynamics have helped to unify these different views. We provide here an overview of the current insights into the transport routes between Golgi and endosomes in mammalian cells. The focus of the Commentary is on the key molecules involved in the trafficking pathways between these intracellular compartments, such as Rab proteins and sorting receptors, and their regulation. A proper understanding of the bidirectional traffic between the Golgi complex and the endolysosomal system is of uttermost importance, as several studies have demonstrated that mutations in the factors involved in these transport pathways result in various pathologies, in particular lysosome-associated diseases and diverse neurological disorders, such as Alzheimer's and Parkinson's disease.
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Affiliation(s)
- Cinzia Progida
- Department of Biosciences, Centre for Immune Regulation, University of Oslo, Oslo, Norway
| | - Oddmund Bakke
- Department of Biosciences, Centre for Immune Regulation, University of Oslo, Oslo, Norway
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173
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Abstract
Tissue-specific transcription regulators emerged as key developmental control genes, which operate in the context of complex gene regulatory networks (GRNs) to coordinate progressive cell fate specification and tissue morphogenesis. We discuss how GRNs control the individual cell behaviors underlying complex morphogenetic events. Cell behaviors classically range from mesenchymal cell motility to cell shape changes in epithelial sheets. These behaviors emerge from the tissue-specific, multiscale integration of the local activities of universal and pleiotropic effectors, which underlie modular subcellular processes including cytoskeletal dynamics, cell-cell and cell-matrix adhesion, signaling, polarity, and vesicle trafficking. Extrinsic cues and intrinsic cell competence determine the subcellular spatiotemporal patterns of effector activities. GRNs influence most subcellular activities by controlling only a fraction of the effector-coding genes, which we argue is enriched in effectors involved in reading and processing the extrinsic cues to contextualize intrinsic subcellular processes and canalize developmental cell behaviors. The properties of the transcription-cell behavior interface have profound implications for evolution and disease.
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Affiliation(s)
- Yelena Bernadskaya
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003
| | - Lionel Christiaen
- Center for Developmental Genetics, Department of Biology, New York University, New York, NY 10003
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174
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Li C, Yu SSB. Rab proteins as regulators of lipid droplet formation and lipolysis. Cell Biol Int 2016; 40:1026-32. [PMID: 27453349 DOI: 10.1002/cbin.10650] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 07/22/2016] [Indexed: 12/11/2022]
Abstract
Lipid droplets (LDs) are highly dynamic organelles that not only store neutral lipids but also are involved in multiple cellular processes. Dysregulation of lipogenesis or lipolysis greatly contributes to the pathogenesis of several human diseases, including obesity, diabetes, and fatty liver disease. Rab proteins have been found to be associated with LDs in proteomic studies and are also known to extensively regulate intracellular membrane traffic, suggesting that LDs actively communicate with other membrane compartments to maintain energy homeostasis. This review discusses recent studies that provide mechanistic insights into the regulation of LD formation and catabolism by Rab proteins in mammalian cells.
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Affiliation(s)
- Chunman Li
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Sidney S B Yu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China. .,Epithelial Cell Biology Research Centre, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China.
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175
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Klinger CM, Ramirez-Macias I, Herman EK, Turkewitz AP, Field MC, Dacks JB. Resolving the homology-function relationship through comparative genomics of membrane-trafficking machinery and parasite cell biology. Mol Biochem Parasitol 2016; 209:88-103. [PMID: 27444378 PMCID: PMC5140719 DOI: 10.1016/j.molbiopara.2016.07.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 07/12/2016] [Accepted: 07/16/2016] [Indexed: 10/21/2022]
Abstract
With advances in DNA sequencing technology, it is increasingly common and tractable to informatically look for genes of interest in the genomic databases of parasitic organisms and infer cellular states. Assignment of a putative gene function based on homology to functionally characterized genes in other organisms, though powerful, relies on the implicit assumption of functional homology, i.e. that orthology indicates conserved function. Eukaryotes reveal a dazzling array of cellular features and structural organization, suggesting a concomitant diversity in their underlying molecular machinery. Significantly, examples of novel functions for pre-existing or new paralogues are not uncommon. Do these examples undermine the basic assumption of functional homology, especially in parasitic protists, which are often highly derived? Here we examine the extent to which functional homology exists between organisms spanning the eukaryotic lineage. By comparing membrane trafficking proteins between parasitic protists and traditional model organisms, where direct functional evidence is available, we find that function is indeed largely conserved between orthologues, albeit with significant adaptation arising from the unique biological features within each lineage.
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Affiliation(s)
- Christen M Klinger
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | | | - Emily K Herman
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada
| | - Aaron P Turkewitz
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
| | - Mark C Field
- School of Life Sciences, University of Dundee, Dundee, UK
| | - Joel B Dacks
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada.
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176
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Rab5 and its effector FHF contribute to neuronal polarity through dynein-dependent retrieval of somatodendritic proteins from the axon. Proc Natl Acad Sci U S A 2016; 113:E5318-27. [PMID: 27559088 PMCID: PMC5018783 DOI: 10.1073/pnas.1601844113] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
An open question in cell biology is how the general intracellular transport machinery is adapted to perform specialized functions in polarized cells such as neurons. Here we illustrate this adaptation by elucidating a role for the ubiquitous small GTPase Ras-related protein in brain 5 (Rab5) in neuronal polarity. We show that inactivation or depletion of Rab5 in rat hippocampal neurons abrogates the somatodendritic polarity of the transferrin receptor and several glutamate receptor types, resulting in their appearance in the axon. This loss of polarity is not caused primarily by increased transport from the soma to the axon but rather by decreased retrieval from the axon to the soma. Retrieval is also dependent on the Rab5 effector Fused Toes (FTS)-Hook-FTS and Hook-interacting protein (FHIP) (FHF) complex, which interacts with the minus-end-directed microtubule motor dynein and its activator dynactin to drive a population of axonal retrograde carriers containing somatodendritic proteins toward the soma. These findings emphasize the importance of both biosynthetic sorting and axonal retrieval for the polarized distribution of somatodendritic receptors at steady state.
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177
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Gershlick DC, Schindler C, Chen Y, Bonifacino JS. TSSC1 is novel component of the endosomal retrieval machinery. Mol Biol Cell 2016; 27:2867-78. [PMID: 27440922 PMCID: PMC5025273 DOI: 10.1091/mbc.e16-04-0209] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 07/13/2016] [Indexed: 12/23/2022] Open
Abstract
A previously uncharacterized WD40 domain–containing protein named TSSC1 is shown to interact with the GARP and EARP tethering complexes, promoting retrograde transport of Shiga toxin from endosomes to the TGN, as well as recycling internalized transferrin from endosomes to the plasma membrane. Endosomes function as a hub for multiple protein-sorting events, including retrograde transport to the trans-Golgi network (TGN) and recycling to the plasma membrane. These processes are mediated by tubular-vesicular carriers that bud from early endosomes and fuse with a corresponding acceptor compartment. Two tethering complexes named GARP (composed of ANG2, VPS52, VPS53, and VPS54 subunits) and EARP (composed of ANG2, VPS52, VPS53, and Syndetin subunits) were previously shown to participate in SNARE-dependent fusion of endosome-derived carriers with the TGN and recycling endosomes, respectively. Little is known, however, about other proteins that function with GARP and EARP in these processes. Here we identify a protein named TSSC1 as a specific interactor of both GARP and EARP and as a novel component of the endosomal retrieval machinery. TSSC1 is a predicted WD40/β-propeller protein that coisolates with both GARP and EARP in affinity purification, immunoprecipitation, and gel filtration analyses. Confocal fluorescence microscopy shows colocalization of TSSC1 with both GARP and EARP. Silencing of TSSC1 impairs transport of internalized Shiga toxin B subunit to the TGN, as well as recycling of internalized transferrin to the plasma membrane. Fluorescence recovery after photobleaching shows that TSSC1 is required for efficient recruitment of GARP to the TGN. These studies thus demonstrate that TSSC1 plays a critical role in endosomal retrieval pathways as a regulator of both GARP and EARP function.
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Affiliation(s)
- David C Gershlick
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Christina Schindler
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Yu Chen
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Juan S Bonifacino
- Cell Biology and Neurobiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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178
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Hurwitz SN, Conlon MM, Rider MA, Brownstein NC, Meckes DG. Nanoparticle analysis sheds budding insights into genetic drivers of extracellular vesicle biogenesis. J Extracell Vesicles 2016; 5:31295. [PMID: 27421995 PMCID: PMC4947197 DOI: 10.3402/jev.v5.31295] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 06/02/2016] [Accepted: 06/07/2016] [Indexed: 01/22/2023] Open
Abstract
Background Extracellular vesicles (EVs) are important mediators of cell-to-cell communication in healthy and pathological environments. Because EVs are present in a variety of biological fluids and contain molecular signatures of their cell or tissue of origin, they have great diagnostic and prognostic value. The ability of EVs to deliver biologically active proteins, RNAs and lipids to cells has generated interest in developing novel therapeutics. Despite their potential medical use, many of the mechanisms underlying EV biogenesis and secretion remain unknown. Methods Here, we characterized vesicle secretion across the NCI-60 panel of human cancer cells by nanoparticle tracking analysis. Using CellMiner, the quantity of EVs secreted by each cell line was compared to reference transcriptomics data to identify gene products associated with vesicle secretion. Results Gene products positively associated with the quantity of exosomal-sized vesicles included vesicular trafficking classes of proteins with Rab GTPase function and sphingolipid metabolism. Positive correlates of larger microvesicle-sized vesicle secretion included gene products involved in cytoskeletal dynamics and exocytosis, as well as Rab GTPase activation. One of the identified targets, CD63, was further evaluated for its role in vesicle secretion. Clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 knockout of the CD63 gene in HEK293 cells resulted in a decrease in small vesicle secretion, suggesting the importance of CD63 in exosome biogenesis. Conclusion These observations reveal new insights into genes involved in exosome and microvesicle formation, and may provide a means to distinguish EV sub-populations. This study offers a foundation for further exploration of targets involved in EV biogenesis and secretion.
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Affiliation(s)
- Stephanie N Hurwitz
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, USA
| | - Meghan M Conlon
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, USA
| | - Mark A Rider
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, USA
| | - Naomi C Brownstein
- Department of Behavioral Sciences and Social Medicine, Florida State University College of Medicine, Tallahassee, FL, USA
| | - David G Meckes
- Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL, USA;
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179
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Kajiho H, Kajiho Y, Frittoli E, Confalonieri S, Bertalot G, Viale G, Di Fiore PP, Oldani A, Garre M, Beznoussenko GV, Palamidessi A, Vecchi M, Chavrier P, Perez F, Scita G. RAB2A controls MT1-MMP endocytic and E-cadherin polarized Golgi trafficking to promote invasive breast cancer programs. EMBO Rep 2016. [PMID: 27255086 DOI: 10.1552/embr.201642032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023] Open
Abstract
The mechanisms of tumor cell dissemination and the contribution of membrane trafficking in this process are poorly understood. Through a functional siRNA screening of human RAB GTPases, we found that RAB2A, a protein essential for ER-to-Golgi transport, is critical in promoting proteolytic activity and 3D invasiveness of breast cancer (BC) cell lines. Remarkably, RAB2A is amplified and elevated in human BC and is a powerful and independent predictor of disease recurrence in BC patients. Mechanistically, RAB2A acts at two independent trafficking steps. Firstly, by interacting with VPS39, a key component of the late endosomal HOPS complex, it controls post-endocytic trafficking of membrane-bound MT1-MMP, an essential metalloprotease for matrix remodeling and invasion. Secondly, it further regulates Golgi transport of E-cadherin, ultimately controlling junctional stability, cell compaction, and tumor invasiveness. Thus, RAB2A is a novel trafficking determinant essential for regulation of a mesenchymal invasive program of BC dissemination.
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Affiliation(s)
- Hiroaki Kajiho
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
| | - Yuko Kajiho
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy Department of Pediatrics, Graduate School of Medicine The University of Tokyo, Tokyo, Japan
| | | | | | - Giovanni Bertalot
- Molecular Medicine Program, European Institute of Oncology, Milan, Italy
| | - Giuseppe Viale
- Department of Oncology and Hemato-Oncology, Università degli Studi di Milano, Milan, Italy Department of Pathology, European Institute of Oncology, Milan, Italy
| | - Pier Paolo Di Fiore
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy Molecular Medicine Program, European Institute of Oncology, Milan, Italy Department of Oncology and Hemato-Oncology, Università degli Studi di Milano, Milan, Italy
| | - Amanda Oldani
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
| | | | | | | | - Manuela Vecchi
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy Molecular Medicine Program, European Institute of Oncology, Milan, Italy
| | - Philippe Chavrier
- Institut Curie, PSL Research University, Paris Cedex 05, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144 CNRS UMR 144, Paris Cedex 05, France
| | - Frank Perez
- Institut Curie, PSL Research University, Paris Cedex 05, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144 CNRS UMR 144, Paris Cedex 05, France
| | - Giorgio Scita
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy Molecular Medicine Program, European Institute of Oncology, Milan, Italy
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180
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Kajiho H, Kajiho Y, Frittoli E, Confalonieri S, Bertalot G, Viale G, Di Fiore PP, Oldani A, Garre M, Beznoussenko GV, Palamidessi A, Vecchi M, Chavrier P, Perez F, Scita G. RAB2A controls MT1-MMP endocytic and E-cadherin polarized Golgi trafficking to promote invasive breast cancer programs. EMBO Rep 2016; 17:1061-80. [PMID: 27255086 DOI: 10.15252/embr.201642032] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 04/28/2016] [Indexed: 11/09/2022] Open
Abstract
The mechanisms of tumor cell dissemination and the contribution of membrane trafficking in this process are poorly understood. Through a functional siRNA screening of human RAB GTPases, we found that RAB2A, a protein essential for ER-to-Golgi transport, is critical in promoting proteolytic activity and 3D invasiveness of breast cancer (BC) cell lines. Remarkably, RAB2A is amplified and elevated in human BC and is a powerful and independent predictor of disease recurrence in BC patients. Mechanistically, RAB2A acts at two independent trafficking steps. Firstly, by interacting with VPS39, a key component of the late endosomal HOPS complex, it controls post-endocytic trafficking of membrane-bound MT1-MMP, an essential metalloprotease for matrix remodeling and invasion. Secondly, it further regulates Golgi transport of E-cadherin, ultimately controlling junctional stability, cell compaction, and tumor invasiveness. Thus, RAB2A is a novel trafficking determinant essential for regulation of a mesenchymal invasive program of BC dissemination.
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Affiliation(s)
- Hiroaki Kajiho
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
| | - Yuko Kajiho
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy Department of Pediatrics, Graduate School of Medicine The University of Tokyo, Tokyo, Japan
| | | | | | - Giovanni Bertalot
- Molecular Medicine Program, European Institute of Oncology, Milan, Italy
| | - Giuseppe Viale
- Department of Oncology and Hemato-Oncology, Università degli Studi di Milano, Milan, Italy Department of Pathology, European Institute of Oncology, Milan, Italy
| | - Pier Paolo Di Fiore
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy Molecular Medicine Program, European Institute of Oncology, Milan, Italy Department of Oncology and Hemato-Oncology, Università degli Studi di Milano, Milan, Italy
| | - Amanda Oldani
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
| | | | | | | | - Manuela Vecchi
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy Molecular Medicine Program, European Institute of Oncology, Milan, Italy
| | - Philippe Chavrier
- Institut Curie, PSL Research University, Paris Cedex 05, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144 CNRS UMR 144, Paris Cedex 05, France
| | - Frank Perez
- Institut Curie, PSL Research University, Paris Cedex 05, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 144 CNRS UMR 144, Paris Cedex 05, France
| | - Giorgio Scita
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy Molecular Medicine Program, European Institute of Oncology, Milan, Italy
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181
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Lőrincz P, Lakatos Z, Varga Á, Maruzs T, Simon-Vecsei Z, Darula Z, Benkő P, Csordás G, Lippai M, Andó I, Hegedűs K, Medzihradszky KF, Takáts S, Juhász G. MiniCORVET is a Vps8-containing early endosomal tether in Drosophila. eLife 2016; 5. [PMID: 27253064 PMCID: PMC4935465 DOI: 10.7554/elife.14226] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 06/01/2016] [Indexed: 01/06/2023] Open
Abstract
Yeast studies identified two heterohexameric tethering complexes, which consist of 4 shared (Vps11, Vps16, Vps18 and Vps33) and 2 specific subunits: Vps3 and Vps8 (CORVET) versus Vps39 and Vps41 (HOPS). CORVET is an early and HOPS is a late endosomal tether. The function of HOPS is well known in animal cells, while CORVET is poorly characterized. Here we show that Drosophila Vps8 is highly expressed in hemocytes and nephrocytes, and localizes to early endosomes despite the lack of a clear Vps3 homolog. We find that Vps8 forms a complex and acts together with Vps16A, Dor/Vps18 and Car/Vps33A, and loss of any of these proteins leads to fragmentation of endosomes. Surprisingly, Vps11 deletion causes enlargement of endosomes, similar to loss of the HOPS-specific subunits Vps39 and Lt/Vps41. We thus identify a 4 subunit-containing miniCORVET complex as an unconventional early endosomal tether in Drosophila. DOI:http://dx.doi.org/10.7554/eLife.14226.001
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Affiliation(s)
- Péter Lőrincz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Zsolt Lakatos
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Ágnes Varga
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Tamás Maruzs
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsófia Simon-Vecsei
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsuzsanna Darula
- Laboratory of Proteomics Research, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Péter Benkő
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Gábor Csordás
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Mónika Lippai
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - István Andó
- Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Krisztina Hegedűs
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Katalin F Medzihradszky
- Laboratory of Proteomics Research, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Szabolcs Takáts
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary
| | - Gábor Juhász
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, Hungary.,Institute of Genetics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
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182
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Topalidou I, Cattin-Ortolá J, Pappas AL, Cooper K, Merrihew GE, MacCoss MJ, Ailion M. The EARP Complex and Its Interactor EIPR-1 Are Required for Cargo Sorting to Dense-Core Vesicles. PLoS Genet 2016; 12:e1006074. [PMID: 27191843 PMCID: PMC4871572 DOI: 10.1371/journal.pgen.1006074] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 04/30/2016] [Indexed: 12/15/2022] Open
Abstract
The dense-core vesicle is a secretory organelle that mediates the regulated release of peptide hormones, growth factors, and biogenic amines. Dense-core vesicles originate from the trans-Golgi of neurons and neuroendocrine cells, but it is unclear how this specialized organelle is formed and acquires its specific cargos. To identify proteins that act in dense-core vesicle biogenesis, we performed a forward genetic screen in Caenorhabditis elegans for mutants defective in dense-core vesicle function. We previously reported the identification of two conserved proteins that interact with the small GTPase RAB-2 to control normal dense-core vesicle cargo-sorting. Here we identify several additional conserved factors important for dense-core vesicle cargo sorting: the WD40 domain protein EIPR-1 and the endosome-associated recycling protein (EARP) complex. By assaying behavior and the trafficking of dense-core vesicle cargos, we show that mutants that lack EIPR-1 or EARP have defects in dense-core vesicle cargo-sorting similar to those of mutants in the RAB-2 pathway. Genetic epistasis data indicate that RAB-2, EIPR-1 and EARP function in a common pathway. In addition, using a proteomic approach in rat insulinoma cells, we show that EIPR-1 physically interacts with the EARP complex. Our data suggest that EIPR-1 is a new interactor of the EARP complex and that dense-core vesicle cargo sorting depends on the EARP-dependent trafficking of cargo through an endosomal sorting compartment. Animal cells package and store many important signaling molecules in specialized compartments called dense-core vesicles. Molecules stored in dense-core vesicles include peptide hormones like insulin and small molecule neurotransmitters like dopamine. Defects in the release of these compounds can lead to a wide range of metabolic and mental disorders in humans, including diabetes, depression, and drug addiction. However, it is not well understood how dense-core vesicles are formed in cells and package the appropriate molecules. Here we use a genetic screen in the microscopic worm C. elegans to identify proteins that are important for early steps in the generation of dense-core vesicles, such as packaging the correct molecular cargos in the vesicles. We identify several factors that are conserved between worms and humans and point to a new role for a protein complex that had previously been shown to be important for controlling trafficking in other cellular compartments. The identification of this complex suggests new cellular trafficking events that may be important for the generation of dense-core vesicles.
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Affiliation(s)
- Irini Topalidou
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Jérôme Cattin-Ortolá
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Andrea L. Pappas
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Kirsten Cooper
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Gennifer E. Merrihew
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Michael J. MacCoss
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Michael Ailion
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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183
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Schroeter S, Beckmann S, Schmitt HD. Coat/Tether Interactions-Exception or Rule? Front Cell Dev Biol 2016; 4:44. [PMID: 27243008 PMCID: PMC4868844 DOI: 10.3389/fcell.2016.00044] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/25/2016] [Indexed: 12/02/2022] Open
Abstract
Coat complexes are important for cargo selection and vesicle formation. Recent evidence suggests that they may also be involved in vesicle targeting. Tethering factors, which form an initial bridge between vesicles and the target membrane, may bind to coat complexes. In this review, we ask whether these coat/tether interactions share some common mechanisms, or whether they are special adaptations to the needs of very specific transport steps. We compare recent findings in two multisubunit tethering complexes, the Dsl1 complex and the HOPS complex, and put them into context with the TRAPP I complex as a prominent example for coat/tether interactions. We explore where coat/tether interactions are found, compare their function and structure, and comment on a possible evolution from a common ancestor of coats and tethers.
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Affiliation(s)
- Saskia Schroeter
- Neurobiology, Max Planck Institute for Biophysical Chemistry Göttingen, Germany
| | - Sabrina Beckmann
- Neurobiology, Max Planck Institute for Biophysical Chemistry Göttingen, Germany
| | - Hans Dieter Schmitt
- Neurobiology, Max Planck Institute for Biophysical Chemistry Göttingen, Germany
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184
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Cheung PYP, Pfeffer SR. Transport Vesicle Tethering at the Trans Golgi Network: Coiled Coil Proteins in Action. Front Cell Dev Biol 2016; 4:18. [PMID: 27014693 PMCID: PMC4791371 DOI: 10.3389/fcell.2016.00018] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 02/29/2016] [Indexed: 12/14/2022] Open
Abstract
The Golgi complex is decorated with so-called Golgin proteins that share a common feature: a large proportion of their amino acid sequences are predicted to form coiled-coil structures. The possible presence of extensive coiled coils implies that these proteins are highly elongated molecules that can extend a significant distance from the Golgi surface. This property would help them to capture or trap inbound transport vesicles and to tether Golgi mini-stacks together. This review will summarize our current understanding of coiled coil tethers that are needed for the receipt of transport vesicles at the trans Golgi network (TGN). How do long tethering proteins actually catch vesicles? Golgi-associated, coiled coil tethers contain numerous binding sites for small GTPases, SNARE proteins, and vesicle coat proteins. How are these interactions coordinated and are any or all of them important for the tethering process? Progress toward understanding these questions and remaining, unresolved mysteries will be discussed.
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Affiliation(s)
- Pak-Yan P Cheung
- Department of Biochemistry, Stanford University School of Medicine Stanford, CA, USA
| | - Suzanne R Pfeffer
- Department of Biochemistry, Stanford University School of Medicine Stanford, CA, USA
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185
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Finding the Golgi: Golgin Coiled-Coil Proteins Show the Way. Trends Cell Biol 2016; 26:399-408. [PMID: 26972448 DOI: 10.1016/j.tcb.2016.02.005] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/08/2016] [Accepted: 02/10/2016] [Indexed: 01/27/2023]
Abstract
The Golgi apparatus lies at the centre of the secretory pathway. It consists of a series of flattened compartments typically organised into a stack that, in mammals, is connected to additional stacks to form a Golgi ribbon. The Golgi is responsible for the maturation and modification of proteins and lipids, and receives and exports vesicles to and from multiple destinations within the cell. This complex trafficking network requires that only the correct vesicles fuse with the correct destination membrane. Recently, a group of coiled-coil proteins called golgins were shown to not only capture incoming vesicles but to also provide specificity to the tethering step. This raises many interesting questions about how they interact with other components of membrane traffic, some of which may also contribute to specificity.
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186
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Fisher P, Ungar D. Bridging the Gap between Glycosylation and Vesicle Traffic. Front Cell Dev Biol 2016; 4:15. [PMID: 27014691 PMCID: PMC4781848 DOI: 10.3389/fcell.2016.00015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 02/22/2016] [Indexed: 11/24/2022] Open
Abstract
Glycosylation is recognized as a vitally important posttranslational modification. The structure of glycans that decorate proteins and lipids is largely dictated by biosynthetic reactions occurring in the Golgi apparatus. This biosynthesis relies on the relative distribution of glycosyltransferases and glycosidases, which is maintained by retrograde vesicle traffic between Golgi cisternae. Tethering of vesicles at the Golgi apparatus prior to fusion is regulated by Rab GTPases, coiled-coil tethers termed golgins and the multisubunit tethering complex known as the conserved oligomeric Golgi (COG) complex. In this review we discuss the mechanisms involved in vesicle tethering at the Golgi apparatus and highlight the importance of tethering in the context of glycan biosynthesis and a set of diseases known as congenital disorders of glycosylation.
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Affiliation(s)
- Peter Fisher
- Department of Biology, University of York York, UK
| | - Daniel Ungar
- Department of Biology, University of York York, UK
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187
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The Conserved VPS-50 Protein Functions in Dense-Core Vesicle Maturation and Acidification and Controls Animal Behavior. Curr Biol 2016; 26:862-71. [PMID: 26948874 DOI: 10.1016/j.cub.2016.01.049] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 11/20/2015] [Accepted: 01/21/2016] [Indexed: 02/05/2023]
Abstract
The modification of behavior in response to experience is crucial for animals to adapt to environmental changes. Although factors such as neuropeptides and hormones are known to function in the switch between alternative behavioral states, the mechanisms by which these factors transduce, store, retrieve, and integrate environmental signals to regulate behavior are poorly understood. The rate of locomotion of the nematode Caenorhabditis elegans depends on both current and past food availability. Specifically, C. elegans slows its locomotion when it encounters food, and animals in a food-deprived state slow even more than animals in a well-fed state. The slowing responses of well-fed and food-deprived animals in the presence of food represent distinct behavioral states, as they are controlled by different sets of genes, neurotransmitters, and neurons. Here we describe an evolutionarily conserved C. elegans protein, VPS-50, that is required for animals to assume the well-fed behavioral state. Both VPS-50 and its murine homolog mVPS50 are expressed in neurons, are associated with synaptic and dense-core vesicles, and control vesicle acidification and hence synaptic function, likely through regulation of the assembly of the V-ATPase complex. We propose that dense-core vesicle acidification controlled by the evolutionarily conserved protein VPS-50/mVPS50 affects behavioral state by modulating neuropeptide levels and presynaptic neuronal function in both C. elegans and mammals.
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188
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Handley MT, Carpanini SM, Mali GR, Sidjanin DJ, Aligianis IA, Jackson IJ, FitzPatrick DR. Warburg Micro syndrome is caused by RAB18 deficiency or dysregulation. Open Biol 2016; 5:150047. [PMID: 26063829 PMCID: PMC4632505 DOI: 10.1098/rsob.150047] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
RAB18, RAB3GAP1, RAB3GAP2 and TBC1D20 are each mutated in Warburg Micro syndrome, a rare autosomal recessive multisystem disorder. RAB3GAP1 and RAB3GAP2 form a binary ‘RAB3GAP’ complex that functions as a guanine-nucleotide exchange factor (GEF) for RAB18, whereas TBC1D20 shows modest RAB18 GTPase-activating (GAP) activity in vitro. Here, we show that in the absence of functional RAB3GAP or TBC1D20, the level, localization and dynamics of cellular RAB18 is altered. In cell lines where TBC1D20 is absent from the endoplasmic reticulum (ER), RAB18 becomes more stably ER-associated and less cytosolic than in control cells. These data suggest that RAB18 is a physiological substrate of TBC1D20 and contribute to a model in which a Rab-GAP can be essential for the activity of a target Rab. Together with previous reports, this indicates that Warburg Micro syndrome can be caused directly by loss of RAB18, or indirectly through loss of RAB18 regulators RAB3GAP or TBC1D20.
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Affiliation(s)
- Mark T Handley
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Sarah M Carpanini
- Division of Neurobiology, The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Girish R Mali
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Duska J Sidjanin
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Irene A Aligianis
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Ian J Jackson
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - David R FitzPatrick
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
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189
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Personnic N, Bärlocher K, Finsel I, Hilbi H. Subversion of Retrograde Trafficking by Translocated Pathogen Effectors. Trends Microbiol 2016; 24:450-462. [PMID: 26924068 DOI: 10.1016/j.tim.2016.02.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/22/2016] [Accepted: 02/01/2016] [Indexed: 12/22/2022]
Abstract
Intracellular bacterial pathogens subvert the endocytic bactericidal pathway to form specific replication-permissive compartments termed pathogen vacuoles or inclusions. To this end, the pathogens employ type III or type IV secretion systems, which translocate dozens, if not hundreds, of different effector proteins into their host cells, where they manipulate vesicle trafficking and signaling pathways in favor of the intruders. While the distinct cocktail of effectors defines the specific processes by which a pathogen vacuole is formed, the different pathogens commonly target certain vesicle trafficking routes, including the endocytic or secretory pathway. Recently, the retrograde transport pathway from endosomal compartments to the trans-Golgi network emerged as an important route affecting pathogen vacuole formation. Here, we review current insight into the host cell's retrograde trafficking pathway and how vacuolar pathogens of the genera Legionella, Coxiella, Salmonella, Chlamydia, and Simkania employ mechanistically distinct strategies to subvert this pathway, thus promoting intracellular survival and replication.
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Affiliation(s)
- Nicolas Personnic
- Institute of Medical Microbiology, Department of Medicine, University of Zürich, Gloriastrasse 30/32, 8006 Zürich, Switzerland
| | - Kevin Bärlocher
- Institute of Medical Microbiology, Department of Medicine, University of Zürich, Gloriastrasse 30/32, 8006 Zürich, Switzerland
| | - Ivo Finsel
- Max von Pettenkofer Institute, Ludwig-Maximilians University Munich, Pettenkoferstrasse 9a, 80336 Munich, Germany
| | - Hubert Hilbi
- Institute of Medical Microbiology, Department of Medicine, University of Zürich, Gloriastrasse 30/32, 8006 Zürich, Switzerland; Max von Pettenkofer Institute, Ludwig-Maximilians University Munich, Pettenkoferstrasse 9a, 80336 Munich, Germany.
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190
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Wu Q, Sun X, Yue W, Lu T, Ruan Y, Chen T, Zhang D. RAB18, a protein associated with Warburg Micro syndrome, controls neuronal migration in the developing cerebral cortex. Mol Brain 2016; 9:19. [PMID: 26879639 PMCID: PMC4754921 DOI: 10.1186/s13041-016-0198-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 02/08/2016] [Indexed: 01/23/2023] Open
Abstract
Background Loss of function mutations in RAB18, has been identified in patients with the human neurological and developmental disorder Warburg Micro syndrome. However, the function of RAB18 in brain remains unknown. Results In this study, we report that RAB18 is a critical regulator of neuronal migration and morphogenesis. Using in utero electroporation suppression of RAB18 in the mouse brain impairs radial migration. Overexpression of dominant negative RAB18 or disruption of RAB3GAP (RAB18GEF) also results in delayed neuronal migration in the developing mouse cortex and inhibition of neurite growth in vitro. Moreover, loss of RAB18 induces an acceleration of N-cadherin degradation by lysosomal pathway resulting in the decrease of surface level of N-cadherin on neurons. Conclusions RAB18 regulates neuronal migration and morphogenesis during development. Our findings highlight the critical role of RAB3GAP-RAB18 pathway in the developing cerebral cortex and might explain some of clinical features observed in patients with Warburg Micro syndrome. Electronic supplementary material The online version of this article (doi:10.1186/s13041-016-0198-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Qinwei Wu
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China. .,Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China. .,Peking University Sixth Hospital/Institute of Mental Health, Beijing, 100191, China.
| | - Xiaqin Sun
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, 100191, China. .,National Clinical Research Center for Mental Disorders/Key Laboratory for Mental Health, Ministry of Health (Peking University), Beijing, 100191, China.
| | - Weihua Yue
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, 100191, China. .,National Clinical Research Center for Mental Disorders/Key Laboratory for Mental Health, Ministry of Health (Peking University), Beijing, 100191, China.
| | - Tianlan Lu
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, 100191, China. .,National Clinical Research Center for Mental Disorders/Key Laboratory for Mental Health, Ministry of Health (Peking University), Beijing, 100191, China.
| | - Yanyan Ruan
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, 100191, China. .,National Clinical Research Center for Mental Disorders/Key Laboratory for Mental Health, Ministry of Health (Peking University), Beijing, 100191, China.
| | - Tianda Chen
- Peking University Sixth Hospital/Institute of Mental Health, Beijing, 100191, China. .,National Clinical Research Center for Mental Disorders/Key Laboratory for Mental Health, Ministry of Health (Peking University), Beijing, 100191, China.
| | - Dai Zhang
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China. .,Peking University Sixth Hospital/Institute of Mental Health, Beijing, 100191, China. .,National Clinical Research Center for Mental Disorders/Key Laboratory for Mental Health, Ministry of Health (Peking University), Beijing, 100191, China. .,PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing, 100871, China.
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191
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Golgi-Resident GTPase Rab30 Promotes the Biogenesis of Pathogen-Containing Autophagosomes. PLoS One 2016; 11:e0147061. [PMID: 26771875 PMCID: PMC4714835 DOI: 10.1371/journal.pone.0147061] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 12/26/2015] [Indexed: 11/22/2022] Open
Abstract
Autophagy acts as a host-defense system against pathogenic microorganisms such as Group A Streptococcus (GAS). Autophagy is a membrane-mediated degradation system that is regulated by intracellular membrane trafficking regulators, including small GTPase Rab proteins. Here, we identified Rab30 as a novel regulator of GAS-containing autophagosome-like vacuoles (GcAVs). We found that Rab30, a Golgi-resident Rab, was recruited to GcAVs in response to autophagy induction by GAS infection in epithelial cells. Rab30 recruitment was dependent upon its GTPase activity. In addition, the knockdown of Rab30 expression significantly reduced GcAV formation efficiency and impaired intracellular GAS degradation. Rab30 normally functions to maintain the structural integrity of the Golgi complex, but GcAV formation occurred even when the Golgi apparatus was disrupted. Although Rab30 also colocalized with a starvation-induced autophagosome, Rab30 was not required for autophagosome formation during starvation. These results suggest that Rab30 mediates autophagy against GAS independently of its normal cellular role in the structural maintenance of the Golgi apparatus, and autophagosome biogenesis during bacterial infection involves specific Rab GTPases.
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192
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Haase G, Rabouille C. Golgi Fragmentation in ALS Motor Neurons. New Mechanisms Targeting Microtubules, Tethers, and Transport Vesicles. Front Neurosci 2015; 9:448. [PMID: 26696811 PMCID: PMC4672084 DOI: 10.3389/fnins.2015.00448] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/13/2015] [Indexed: 12/12/2022] Open
Abstract
Pathological alterations of the Golgi apparatus, such as its fragmentation represent an early pre-clinical feature of many neurodegenerative diseases and have been widely studied in the motor neuron disease amyotrophic lateral sclerosis (ALS). Yet, the underlying molecular mechanisms have remained cryptic. In principle, Golgi fragmentation may result from defects in three major classes of proteins: structural Golgi proteins, cytoskeletal proteins and molecular motors, as well as proteins mediating transport to and through the Golgi. Here, we present the different mechanisms that may underlie Golgi fragmentation in animal and cellular models of ALS linked to mutations in SOD1, TARDBP (TDP-43), VAPB, and C9Orf72 and we propose a novel one based on findings in progressive motor neuronopathy (pmn) mice. These mice are mutated in the TBCE gene encoding the cis-Golgi localized tubulin-binding cofactor E, one of five chaperones that assist in tubulin folding and microtubule polymerization. Loss of TBCE leads to alterations in Golgi microtubules, which in turn impedes on the maintenance of the Golgi architecture. This is due to down-regulation of COPI coat components, dispersion of Golgi tethers and strong accumulation of ER-Golgi SNAREs. These effects are partially rescued by the GTPase ARF1 through recruitment of TBCE to the Golgi. We hypothesize that defects in COPI vesicles, microtubules and their interaction may also underlie Golgi fragmentation in human ALS linked to other mutations, spinal muscular atrophy (SMA), and related motor neuron diseases. We also discuss the functional relevance of pathological Golgi alterations, in particular their potential causative, contributory, or compensatory role in the degeneration of motor neuron cell bodies, axons and synapses.
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Affiliation(s)
- Georg Haase
- Centre National de la Recherche Scientifique and Aix-Marseille Université UMR 7289, Institut de Neurosciences de la Timone Marseille, France
| | - Catherine Rabouille
- The Department of Cell Biology, Hubrecht Institute of the Royal Netherlands Academy of Arts and Sciences and University Medical Center Utrecht Utrecht, Netherlands
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193
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Khatter D, Sindhwani A, Sharma M. Arf-like GTPase Arl8: Moving from the periphery to the center of lysosomal biology. CELLULAR LOGISTICS 2015; 5:e1086501. [PMID: 27057420 DOI: 10.1080/21592799.2015.1086501] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 08/15/2015] [Accepted: 08/19/2015] [Indexed: 02/08/2023]
Abstract
Lysosomes are dynamic organelles that not only mediate degradation of cellular substrates but also play critical roles in processes such as cholesterol homeostasis, plasma membrane repair, antigen presentation, and cell migration. The small GTPase Arl8, a member of Arf-like (Arl) family of proteins, has recently emerged as a crucial regulator of lysosome positioning and membrane trafficking toward lysosomes. Through interaction with its effector SKIP, the human Arl8 paralog (Arl8b) mediates kinesin-1 dependent motility of lysosomes on microtubule tracks toward the cell periphery. Arl8b-mediated kinesin-driven motility is also implicated in regulating lytic granule polarization in NK cells, lysosome tubulation in macrophages, cell spreading, and migration. Moreover, Arl8b regulates membrane traffic toward lysosomes by recruiting subunits of the HOPS complex, a multi-subunit tethering complex that mediates endo-lysosome fusion. Here we provide a brief review on this recently characterized lysosomal GTPase and summarize the studies focusing on its known functions in regulating lysosomal motility and delivery of endocytic cargo to the lysosomes. We also explore the role of human Arl8b and its orthologs upon infection by intracellular pathogens.
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Affiliation(s)
- Divya Khatter
- Department of Biological Sciences; Indian Institute of Science Education and Research-Mohali (IISERM) ; Mohali, India
| | - Aastha Sindhwani
- Department of Biological Sciences; Indian Institute of Science Education and Research-Mohali (IISERM) ; Mohali, India
| | - Mahak Sharma
- Department of Biological Sciences; Indian Institute of Science Education and Research-Mohali (IISERM) ; Mohali, India
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194
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Dunst S, Kazimiers T, von Zadow F, Jambor H, Sagner A, Brankatschk B, Mahmoud A, Spannl S, Tomancak P, Eaton S, Brankatschk M. Endogenously tagged rab proteins: a resource to study membrane trafficking in Drosophila. Dev Cell 2015; 33:351-65. [PMID: 25942626 PMCID: PMC4431667 DOI: 10.1016/j.devcel.2015.03.022] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 01/21/2015] [Accepted: 03/29/2015] [Indexed: 11/25/2022]
Abstract
Membrane trafficking is key to the cell biological mechanisms underlying development. Rab GTPases control specific membrane compartments, from core secretory and endocytic machinery to less-well-understood compartments. We tagged all 27 Drosophila Rabs with YFP(MYC) at their endogenous chromosomal loci, determined their expression and subcellular localization in six tissues comprising 23 cell types, and provide this data in an annotated, searchable image database. We demonstrate the utility of these lines for controlled knockdown and show that similar subcellular localization can predict redundant functions. We exploit this comprehensive resource to ask whether a common Rab compartment architecture underlies epithelial polarity. Strikingly, no single arrangement of Rabs characterizes the five epithelia we examine. Rather, epithelia flexibly polarize Rab distribution, producing membrane trafficking architectures that are tissue- and stage-specific. Thus, the core machinery responsible for epithelial polarization is unlikely to rely on polarized positioning of specific Rab compartments.
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Affiliation(s)
- Sebastian Dunst
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Tom Kazimiers
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; HHMI Janelia Research Campus, Ashburn, VA 20147, USA
| | - Felix von Zadow
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Helena Jambor
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Andreas Sagner
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; MRC National Institute for Medical Research, London NW7 1AA, UK
| | - Beate Brankatschk
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; Paul Langerhans Institute, Dresden 01307, Germany
| | - Ali Mahmoud
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Stephanie Spannl
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Pavel Tomancak
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany.
| | - Suzanne Eaton
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany.
| | - Marko Brankatschk
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany.
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195
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Disruption of Endocytosis with the Dynamin Mutant shibirets1 Suppresses Seizures in Drosophila. Genetics 2015; 201:1087-102. [PMID: 26341658 DOI: 10.1534/genetics.115.177600] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 08/31/2015] [Indexed: 11/18/2022] Open
Abstract
One challenge in modern medicine is to control epilepsies that do not respond to currently available medications. Since seizures consist of coordinated and high-frequency neural activity, our goal was to disrupt neurotransmission with a synaptic transmission mutant and evaluate its ability to suppress seizures. We found that the mutant shibire, encoding dynamin, suppresses seizure-like activity in multiple seizure-sensitive Drosophila genotypes, one of which resembles human intractable epilepsy in several aspects. Because of the requirement of dynamin in endocytosis, increased temperature in the shi(ts1) mutant causes impairment of synaptic vesicle recycling and is associated with suppression of the seizure-like activity. Additionally, we identified the giant fiber neuron as critical in the seizure circuit and sufficient to suppress seizures. Overall, our results implicate mutant dynamin as an effective seizure suppressor, suggesting that targeting or limiting the availability of synaptic vesicles could be an effective and general method of controlling epilepsy disorders.
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196
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Abstract
Rab GTPases control intracellular membrane traffic by recruiting specific effector proteins to restricted membranes in a GTP-dependent manner. In this Cell Science at a Glance and the accompanying poster, we highlight the regulation of Rab GTPases by proteins that control their membrane association and activation state, and provide an overview of the cellular processes that are regulated by Rab GTPases and their effectors, including protein sorting, vesicle motility and vesicle tethering. We also discuss the physiological importance of Rab GTPases and provide examples of diseases caused by their dysfunctions.
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Affiliation(s)
- Yan Zhen
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo N-0379, Norway Department for Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo N-0379, Norway
| | - Harald Stenmark
- Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, Montebello, Oslo N-0379, Norway Department for Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Montebello, Oslo N-0379, Norway
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197
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Lee M, Ko YJ, Moon Y, Han M, Kim HW, Lee SH, Kang K, Jun Y. SNAREs support atlastin-mediated homotypic ER fusion in Saccharomyces cerevisiae. J Cell Biol 2015. [PMID: 26216899 PMCID: PMC4523606 DOI: 10.1083/jcb.201501043] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dynamin-like GTPases of the atlastin family are thought to mediate homotypic endoplasmic reticulum (ER) membrane fusion; however, the underlying mechanism remains largely unclear. Here, we developed a simple and quantitative in vitro assay using isolated yeast microsomes for measuring yeast atlastin Sey1p-dependent ER fusion. Using this assay, we found that the ER SNAREs Sec22p and Sec20p were required for Sey1p-mediated ER fusion. Consistently, ER fusion was significantly reduced by inhibition of Sec18p and Sec17p, which regulate SNARE-mediated membrane fusion. The involvement of SNAREs in Sey1p-dependent ER fusion was further supported by the physical interaction of Sey1p with Sec22p and Ufe1p, another ER SNARE. Furthermore, our estimation of the concentration of Sey1p on isolated microsomes, together with the lack of fusion between Sey1p proteoliposomes even with a 25-fold excess of the physiological concentration of Sey1p, suggests that Sey1p requires additional factors to support ER fusion in vivo. Collectively, our data strongly suggest that SNARE-mediated membrane fusion is involved in atlastin-initiated homotypic ER fusion.
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Affiliation(s)
- Miriam Lee
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Young-Joon Ko
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Yeojin Moon
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Minsoo Han
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - Hyung-Wook Kim
- College of Life Sciences, Sejong University, Seoul 143-747, Korea
| | - Sung Haeng Lee
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, Gwangju 501-759, Korea
| | - KyeongJin Kang
- Department of Anatomy and Cell Biology, School of Medicine, Sungkyunkwan University, Suwon 440-746, Korea
| | - Youngsoo Jun
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Integrative Aging Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea Cell Dynamics Research Center, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
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198
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Hierro A, Gershlick DC, Rojas AL, Bonifacino JS. Formation of Tubulovesicular Carriers from Endosomes and Their Fusion to the trans-Golgi Network. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 318:159-202. [PMID: 26315886 DOI: 10.1016/bs.ircmb.2015.05.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Endosomes undergo extensive spatiotemporal rearrangements as proteins and lipids flux through them in a series of fusion and fission events. These controlled changes enable the concentration of cargo for eventual degradation while ensuring the proper recycling of other components. A growing body of studies has now defined multiple recycling pathways from endosomes to the trans-Golgi network (TGN) which differ in their molecular machineries. The recycling process requires specific sets of lipids, coats, adaptors, and accessory proteins that coordinate cargo selection with membrane deformation and its association with the cytoskeleton. Specific tethering factors and SNARE (SNAP (Soluble NSF Attachment Protein) Receptor) complexes are then required for the docking and fusion with the acceptor membrane. Herein, we summarize some of the current knowledge of the machineries that govern the retrograde transport from endosomes to the TGN.
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Affiliation(s)
- Aitor Hierro
- Structural Biology Unit, CIC bioGUNE, Derio, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - David C Gershlick
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - Juan S Bonifacino
- Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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199
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Kuhlee A, Raunser S, Ungermann C. Functional homologies in vesicle tethering. FEBS Lett 2015; 589:2487-97. [PMID: 26072291 DOI: 10.1016/j.febslet.2015.06.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 05/30/2015] [Accepted: 06/01/2015] [Indexed: 11/24/2022]
Abstract
The HOPS multisubunit tethering factor (MTC) is a macromolecular protein complex composed of six different subunits. It is one of the key components in the perception and subsequent fusion of multivesicular bodies and vacuoles. Electron microscopy studies indicate structural flexibility of the purified HOPS complex. Inducing higher rigidity into HOPS by biochemically modifying the complex declines the potential to mediate SNARE-driven membrane fusion. Thus, we propose that integral flexibility seems to be not only a feature, but of essential need for the function of HOPS. This review focuses on the general features of membrane tethering and fusion. For this purpose, we compare the structure and mode of action of different tethering factors to highlight their common central features and mechanisms.
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Affiliation(s)
- Anne Kuhlee
- Department of Structural Biochemistry, Max-Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.
| | - Stefan Raunser
- Department of Structural Biochemistry, Max-Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Christian Ungermann
- Department of Biology, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany
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200
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Xiang X, Qiu R, Yao X, Arst HN, Peñalva MA, Zhang J. Cytoplasmic dynein and early endosome transport. Cell Mol Life Sci 2015; 72:3267-80. [PMID: 26001903 DOI: 10.1007/s00018-015-1926-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 05/04/2015] [Accepted: 05/05/2015] [Indexed: 11/25/2022]
Abstract
Microtubule-based distribution of organelles/vesicles is crucial for the function of many types of eukaryotic cells and the molecular motor cytoplasmic dynein is required for transporting a variety of cellular cargos toward the microtubule minus ends. Early endosomes represent a major cargo of dynein in filamentous fungi, and dynein regulators such as LIS1 and the dynactin complex are both required for early endosome movement. In fungal hyphae, kinesin-3 and dynein drive bi-directional movements of early endosomes. Dynein accumulates at microtubule plus ends; this accumulation depends on kinesin-1 and dynactin, and it is important for early endosome movements towards the microtubule minus ends. The physical interaction between dynein and early endosome requires the dynactin complex, and in particular, its p25 component. The FTS-Hook-FHIP (FHF) complex links dynein-dynactin to early endosomes, and within the FHF complex, Hook interacts with dynein-dynactin, and Hook-early endosome interaction depends on FHIP and FTS.
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Affiliation(s)
- Xin Xiang
- Department of Biochemistry and Molecular Biology, F. Edward Hébert School of Medicine, The Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD, 20814, USA,
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