1
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DAmico KA, Stanton AE, Shirkey JD, Travis SM, Jeffrey PD, Hughson FM. Structure of a membrane tethering complex incorporating multiple SNAREs. Nat Struct Mol Biol 2024; 31:246-254. [PMID: 38196032 PMCID: PMC10923073 DOI: 10.1038/s41594-023-01164-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 10/26/2023] [Indexed: 01/11/2024]
Abstract
Most membrane fusion reactions in eukaryotic cells are mediated by multisubunit tethering complexes (MTCs) and SNARE proteins. MTCs are much larger than SNAREs and are thought to mediate the initial attachment of two membranes. Complementary SNAREs then form membrane-bridging complexes whose assembly draws the membranes together for fusion. Here we present a cryo-electron microscopy structure of the simplest known MTC, the 255-kDa Dsl1 complex of Saccharomyces cerevisiae, bound to the two SNAREs that anchor it to the endoplasmic reticulum. N-terminal domains of the SNAREs form an integral part of the structure, stabilizing a Dsl1 complex configuration with unexpected similarities to the 850-kDa exocyst MTC. The structure of the SNARE-anchored Dsl1 complex and its comparison with exocyst reveal what are likely to be common principles underlying MTC function. Our structure also implies that tethers and SNAREs can work together as a single integrated machine.
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Affiliation(s)
- Kevin A DAmico
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Abigail E Stanton
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Jaden D Shirkey
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Sophie M Travis
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Philip D Jeffrey
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
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2
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Ji Q, Zhang K, Cao N, You X, Cao S, Wang M, Guo J, Wang H, Mei K. Highly efficient overexpression and purification of multisubunit tethering complexes in Saccharomyces cerevisiae. Protein Expr Purif 2023; 212:106351. [PMID: 37574178 DOI: 10.1016/j.pep.2023.106351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 08/02/2023] [Accepted: 08/09/2023] [Indexed: 08/15/2023]
Abstract
Vesicle trafficking is a fundamental cellular process that ensures proper material exchange between organelles in eukaryotic cells, and multisubunit tethering complexes (MTCs) are essential in this process. The heterohexameric homotypic fusion and protein sorting (HOPS) complex, which functions in the endolysosomal pathway, is a member of MTCs. Despite its critical role, the complex composition and low-expression level of HOPS have made its expression and purification extremely challenging. In this study, we present a highly efficient strategy for overexpressing and purifying HOPS from Saccharomyces cerevisiae. We achieved HOPS overexpression by integrating a strong promoter TEF1 before each subunit using the gRNA-tRNA array for CRISPR-Cas9 (GTR-CRISPR) system. The HOPS complex was subsequently purified using Staphylococcus aureus protein A (ProtA) affinity purification and size-exclusion chromatography, resulting in high purity and homogeneity. We obtained two-fold more HOPS using this method than that obtained using the commonly used GAL1 promoter-controlled HOPS overexpression. Negative staining electron microscopy analysis confirmed the correct assembly of HOPS. Notably, we also successfully purified two other MTCs, class C core vacuole/endosome tethering (CORVET) and Golgi-associated retrograde protein (GARP) using this approach. Our findings facilitate further in vitro biochemical characterization and functional studies of MTCs and provide a useful guide for the preparation of other heterogenic multisubunit complexes.
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Affiliation(s)
- Qiushuang Ji
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China.
| | - Ke Zhang
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China.
| | - Na Cao
- School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| | - Xiaoyu You
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China.
| | - Shuaihua Cao
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China.
| | - Mengya Wang
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China.
| | - Jiatian Guo
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China.
| | - Hongwei Wang
- School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| | - Kunrong Mei
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China.
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3
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Lai CC, Chiu WY, Chen YT, Wu CL, Lee FJS. The SNARE-associated protein Sft2 functions in Imh1-mediated SNARE recycling transport upon ER stress. Mol Biol Cell 2023; 34:ar112. [PMID: 37610835 PMCID: PMC10559307 DOI: 10.1091/mbc.e23-01-0019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 08/07/2023] [Accepted: 08/15/2023] [Indexed: 08/25/2023] Open
Abstract
Vesicular trafficking involving SNARE proteins play a crucial role in the delivery of cargo to the target membrane. Arf-like protein 1 (Arl1) is an important regulator of the endosomal trans-Golgi network (TGN) and secretory trafficking. In yeast, ER stress-enhances Arl1 activation and Golgin Imh1 recruitment to the late-Golgi. Although Arl1 and Imh1 are critical for GARP-mediated endosomal SNARE-recycling transport in response to ER stress, their downstream effectors are unknown. Here, we report that the SNARE-associated protein Sft2 acts downstream of the Arl1-Imh1 axis to regulate SNARE recycling upon ER stress. We first demonstrated that Sft2 is required for Tlg1/Snc1 SNARE-recycling transport under tunicamycin-induced ER stress. Interestingly, we found that Imh1 regulates Tlg2 retrograde transport to the late-Golgi under ER stress, which in turn is required for Sft2 targeting to the late-Golgi. We further showed that Sft2 with 40 amino acids deleted from the N-terminus exhibits defective mediation of SNARE recycling and decreased association with Tlg1 under ER stress. Finally, we demonstrated that Sft2 is required for GARP-dependent endosome-to-Golgi transport in the absence of Rab protein Ypt6. This study highlights Sft2 as a critical downstream effector of the Arl1-Imh1 axis, mediating the endosome-to-Golgi transport of SNAREs.
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Affiliation(s)
- Chun-Chi Lai
- Institute of Molecular Medicine, National Taiwan University, Taipei 10002, Taiwan
- Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Wan-Yun Chiu
- Institute of Molecular Medicine, National Taiwan University, Taipei 10002, Taiwan
- Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Yan-Ting Chen
- Institute of Molecular Medicine, National Taiwan University, Taipei 10002, Taiwan
- Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Chia-Lu Wu
- Institute of Molecular Medicine, National Taiwan University, Taipei 10002, Taiwan
- Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | - Fang-Jen S. Lee
- Institute of Molecular Medicine, National Taiwan University, Taipei 10002, Taiwan
- Center of Precision Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
- Department of Medical Research, National Taiwan University Hospital, Taipei 100, Taiwan
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4
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Filandrova R, Douglas P, Zhan X, Verhey TB, Morrissy S, Turner RW, Schriemer DC. Mouse Model of Fragile X Syndrome Analyzed by Quantitative Proteomics: A Comparison of Methods. J Proteome Res 2023; 22:3054-3067. [PMID: 37595185 DOI: 10.1021/acs.jproteome.3c00363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2023]
Abstract
Multiple methods for quantitative proteomics are available for proteome profiling. It is unclear which methods are most useful in situations involving deep proteome profiling and the detection of subtle distortions in the proteome. Here, we compared the performance of seven different strategies in the analysis of a mouse model of Fragile X Syndrome, involving the knockout of the fmr1 gene that is the leading cause of autism spectrum disorder. Focusing on the cerebellum, we show that data-independent acquisition (DIA) and the tandem mass tag (TMT)-based real-time search method (RTS) generated the most informative profiles, generating 334 and 329 significantly altered proteins, respectively, although the latter still suffered from ratio compression. Label-free methods such as BoxCar and a conventional data-dependent acquisition were too noisy to generate a reliable profile, while TMT methods that do not invoke RTS showed a suppressed dynamic range. The TMT method using the TMTpro reagents together with complementary ion quantification (ProC) overcomes ratio compression, but current limitations in ion detection reduce sensitivity. Overall, both DIA and RTS uncovered known regulators of the syndrome and detected alterations in calcium signaling pathways that are consistent with calcium deregulation recently observed in imaging studies. Data are available via ProteomeXchange with the identifier PXD039885.
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Affiliation(s)
- Ruzena Filandrova
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Pauline Douglas
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Xiaoqin Zhan
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Theodore B Verhey
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Sorana Morrissy
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Raymond W Turner
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - David C Schriemer
- Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Department of Chemistry, University of Calgary, Calgary, Alberta T2N 4N1, Canada
- Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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5
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Li X, Liu D, Griffis E, Novick P. Exploring the consequences of redirecting an exocytic Rab onto endocytic vesicles. Mol Biol Cell 2023; 34:ar38. [PMID: 36857153 PMCID: PMC10162416 DOI: 10.1091/mbc.e23-01-0037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 02/22/2023] [Indexed: 03/02/2023] Open
Abstract
Bidirectional vesicular traffic links compartments along the exocytic and endocytic pathways. Rab GTPases have been implicated in specifying the direction of vesicular transport. To explore this possibility, we sought to redirect an exocytic Rab, Sec4, onto endocytic vesicles by fusing the catalytic domain of the Sec4 GEF, Sec2, onto the CUE localization domain of Vps9, a GEF for the endocytic Rab Ypt51. The Sec2GEF-GFP-CUE construct localized to bright puncta predominantly near sites of polarized growth, and this localization was dependent on the ability of the CUE domain to bind to the ubiquitin moieties added to the cytoplasmic tails of proteins destined for endocytic internalization. Sec4 and Sec4 effectors were recruited to these puncta with various efficiencies. Cells expressing Sec2GEF-GFP-CUE grew surprisingly well and secreted protein at near-normal efficiency, implying that Golgi-derived secretory vesicles were delivered to polarized sites of cell growth despite the misdirection of Sec4 and its effectors. A low efficiency mechanism for localization of Sec2 to secretory vesicles that is independent of known cues might be responsible. In total, the results suggest that while Rabs may play a critical role in specifying the direction of vesicular transport, cells are remarkably tolerant of Rab misdirection.
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Affiliation(s)
- Xia Li
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093-0644
| | - Dongmei Liu
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093-0644
| | - Eric Griffis
- Nikon Imaging Center, University of California, San Diego, La Jolla, CA 92093-0694
| | - Peter Novick
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093-0644
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6
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Sun S, Sui SF. Structural insights into assembly of TRAPPII and its activation of Rab11/Ypt32. Curr Opin Struct Biol 2023; 80:102596. [PMID: 37068358 DOI: 10.1016/j.sbi.2023.102596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 03/09/2023] [Accepted: 03/19/2023] [Indexed: 04/19/2023]
Abstract
Transport protein particle (TRAPP) complexes belong to the multisubunit tethering complex. They are guanine nucleotide exchange factors (GEFs) that play essential roles in secretory and endocytic recycling pathway and autophagy. There are two major forms of TRAPP complexes, TRAPPII and TRAPPIII, which share a core set of small subunits. TRAPPIII activates Rab1, while TRAPPII primarily activates Rab11. A steric gating mechanism has been proposed to control the substrate selection in vivo. However, the detailed mechanisms underlying the transition from TRAPPIII's GEF activity for Rab1 to TRAPPII's GEF activity for Rab11 and the roles of the complex-specific subunits in this transition are insufficiently understood. In this review, we discuss recent advances in understanding the mechanism of specific activation of Rab11/Ypt32 by TRAPPII, with a particular focus on new findings from structural studies.
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Affiliation(s)
- Shan Sun
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Sen-Fang Sui
- State Key Laboratory of Membrane Biology, Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; School of Life Sciences, Cryo-EM Center, Southern University of Science and Technology, Shenzhen 518055, Guangdong, China
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7
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Li X, Liu D, Griffis E, Novick P. Exploring the consequences of redirecting an exocytic Rab onto endocytic vesicles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.09.527811. [PMID: 36798320 PMCID: PMC9934678 DOI: 10.1101/2023.02.09.527811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Bidirectional vesicular traffic links compartments along the exocytic and endocytic pathways. Rab GTPases have been implicated in specifying the direction of vesicular transport because anterograde vesicles are marked with a different Rab than retrograde vesicles. To explore this proposal, we sought to redirect an exocytic Rab, Sec4, onto endocytic vesicles by fusing the catalytic domain of the Sec4 GEF, Sec2, onto the CUE localization domain of Vps9, a GEF for the endocytic Rab, Ypt51. The Sec2GEF-GFP-CUE construct was found to localize to bright puncta predominantly near sites of polarized growth and this localization was strongly dependent upon the ability of the CUE domain to bind to the ubiquitin moieties added to the cytoplasmic tails of proteins destined for endocytic internalization. Sec4 and Sec4 effectors were recruited to these puncta with varying efficiency. The puncta appeared to consist of clusters of 80 nm vesicles and although the puncta are largely static, FRAP analysis suggests that traffic into and out of these clusters continues. Cells expressing Sec2GEF-GFP-CUE grew surprisingly well and secreted protein at near normal efficiency, implying that Golgi derived secretory vesicles were delivered to polarized sites of cell growth, where they tethered and fused with the plasma membrane despite the misdirection of Sec4 and its effectors. In total, the results suggest that while Rabs play a critical role in regulating vesicular transport, cells are remarkably tolerant of Rab misdirection.
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Affiliation(s)
- Xia Li
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California, United States
| | - Dongmei Liu
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California, United States
| | - Eric Griffis
- Nikon Imaging Center, University of California at San Diego, La Jolla, California, United States
| | - Peter Novick
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, California, United States
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8
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DAmico KA, Stanton AE, Shirkey JD, Travis SM, Jeffrey PD, Hughson FM. Structure of a Membrane Tethering Complex Incorporating Multiple SNAREs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.30.526244. [PMID: 36778436 PMCID: PMC9915479 DOI: 10.1101/2023.01.30.526244] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Most membrane fusion reactions in eukaryotic cells are mediated by membrane tethering complexes (MTCs) and SNARE proteins. MTCs are much larger than SNAREs and are thought to mediate the initial attachment of two membranes. Complementary SNAREs then form membrane-bridging complexes whose assembly draws the membranes together for fusion. Here, we present a cryo-EM structure of the simplest known MTC, the 255-kDa Dsl1 complex, bound to the two SNAREs that anchor it to the endoplasmic reticulum. N-terminal domains of the SNAREs form an integral part of the structure, stabilizing a Dsl1 complex configuration with remarkable and unexpected similarities to the 850-kDa exocyst MTC. The structure of the SNARE-anchored Dsl1 complex and its comparison with exocyst reveal what are likely to be common principles underlying MTC function. Our structure also implies that tethers and SNAREs can work together as a single integrated machine.
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Affiliation(s)
- Kevin A DAmico
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - Abigail E Stanton
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - Jaden D Shirkey
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - Sophie M Travis
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
| | - Philip D Jeffrey
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544
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9
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Palfreyman MT, West SE, Jorgensen EM. SNARE Proteins in Synaptic Vesicle Fusion. ADVANCES IN NEUROBIOLOGY 2023; 33:63-118. [PMID: 37615864 DOI: 10.1007/978-3-031-34229-5_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Neurotransmitters are stored in small membrane-bound vesicles at synapses; a subset of synaptic vesicles is docked at release sites. Fusion of docked vesicles with the plasma membrane releases neurotransmitters. Membrane fusion at synapses, as well as all trafficking steps of the secretory pathway, is mediated by SNARE proteins. The SNAREs are the minimal fusion machinery. They zipper from N-termini to membrane-anchored C-termini to form a 4-helix bundle that forces the apposed membranes to fuse. At synapses, the SNAREs comprise a single helix from syntaxin and synaptobrevin; SNAP-25 contributes the other two helices to complete the bundle. Unc13 mediates synaptic vesicle docking and converts syntaxin into the permissive "open" configuration. The SM protein, Unc18, is required to initiate and proofread SNARE assembly. The SNAREs are then held in a half-zippered state by synaptotagmin and complexin. Calcium removes the synaptotagmin and complexin block, and the SNAREs drive vesicle fusion. After fusion, NSF and alpha-SNAP unwind the SNAREs and thereby recharge the system for further rounds of fusion. In this chapter, we will describe the discovery of the SNAREs, their relevant structural features, models for their function, and the central role of Unc18. In addition, we will touch upon the regulation of SNARE complex formation by Unc13, complexin, and synaptotagmin.
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Affiliation(s)
- Mark T Palfreyman
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Sam E West
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA
| | - Erik M Jorgensen
- School of Biological Sciences, and Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT, USA.
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10
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Pallares R, An DD, Hébert S, Loguinov A, Proctor M, Villalobos JA, Bjornstad KA, Rosen CJ, Vulpe CD, Abergel RJ. Identifying Toxicity Mechanisms Associated with Early Lanthanide Exposure through Multidimensional Genome-Wide Screening. ACS OMEGA 2022; 7:34412-34419. [PMID: 36188298 PMCID: PMC9521019 DOI: 10.1021/acsomega.2c04045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 09/01/2022] [Indexed: 06/16/2023]
Abstract
Lanthanides are a series of elements essential to a wide range of applications, from clean energy production to healthcare. Despite their presence in multiple products and technologies, their toxicological characteristics have been only partly studied. Recently, our group has employed a genomic approach to extensively characterize the toxicity mechanisms of lanthanides. Even though we identified substantially different behaviors for mid and late lanthanides, the toxicological profiles of early lanthanides remained elusive. Here, we overcome this gap by describing a multidimensional genome-wide toxicogenomic study for two early lanthanides, namely, lanthanum and praseodymium. We used Saccharomyces cerevisiae as a model system since its genome shares many biological pathways with humans. By performing functional analysis and protein-protein interaction network analysis, we identified the main genes and proteins that participate in the yeast response to counter metal harmful effects. Moreover, our analysis also highlighted key enzymes that are dysregulated by early lanthanides, inducing cytotoxicity. Several of these genes and proteins have human orthologues, indicating that they may also participate in the human response against the metals. By highlighting the key genes and proteins in lanthanide-induced toxicity, this work may contribute to the development of new prophylactic and therapeutic strategies against lanthanide harmful exposures.
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Affiliation(s)
- Roger
M. Pallares
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Dahlia D. An
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Solène Hébert
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Alex Loguinov
- Center
for Environmental and Human Toxicology, Department of Physiological
Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611, United States
| | - Michael Proctor
- Center
for Environmental and Human Toxicology, Department of Physiological
Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611, United States
| | - Jonathan A. Villalobos
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Kathleen A. Bjornstad
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Chris J. Rosen
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
| | - Chris D. Vulpe
- Center
for Environmental and Human Toxicology, Department of Physiological
Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611, United States
| | - Rebecca J. Abergel
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Department
of Nuclear Engineering, University of California, Berkeley, California 94720, United States
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11
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Synaptic Secretion and Beyond: Targeting Synapse and Neurotransmitters to Treat Neurodegenerative Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:9176923. [PMID: 35923862 PMCID: PMC9343216 DOI: 10.1155/2022/9176923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/16/2022] [Accepted: 06/04/2022] [Indexed: 11/17/2022]
Abstract
The nervous system is important, because it regulates the physiological function of the body. Neurons are the most basic structural and functional unit of the nervous system. The synapse is an asymmetric structure that is important for neuronal function. The chemical transmission mode of the synapse is realized through neurotransmitters and electrical processes. Based on vesicle transport, the abnormal information transmission process in the synapse can lead to a series of neurorelated diseases. Numerous proteins and complexes that regulate the process of vesicle transport, such as SNARE proteins, Munc18-1, and Synaptotagmin-1, have been identified. Their regulation of synaptic vesicle secretion is complicated and delicate, and their defects can lead to a series of neurodegenerative diseases. This review will discuss the structure and functions of vesicle-based synapses and their roles in neurons. Furthermore, we will analyze neurotransmitter and synaptic functions in neurodegenerative diseases and discuss the potential of using related drugs in their treatment.
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12
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Fadil SA, Janetopoulos C. The Polarized Redistribution of the Contractile Vacuole to the Rear of the Cell is Critical for Streaming and is Regulated by PI(4,5)P2-Mediated Exocytosis. Front Cell Dev Biol 2022; 9:765316. [PMID: 35928786 PMCID: PMC9344532 DOI: 10.3389/fcell.2021.765316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/20/2021] [Indexed: 12/05/2022] Open
Abstract
Dictyostelium discoideum amoebae align in a head to tail manner during the process of streaming during fruiting body formation. The chemoattractant cAMP is the chemoattractant regulating cell migration during this process and is released from the rear of cells. The process by which this cAMP release occurs has eluded investigators for many decades, but new findings suggest that this release can occur through expulsion during contractile vacuole (CV) ejection. The CV is an organelle that performs several functions inside the cell including the regulation of osmolarity, and discharges its content via exocytosis. The CV localizes to the rear of the cell and appears to be part of the polarity network, with the localization under the influence of the plasma membrane (PM) lipids, including the phosphoinositides (PIs), among those is PI(4,5)P2, the most abundant PI on the PM. Research on D. discoideum and neutrophils have shown that PI(4,5)P2 is enriched at the rear of migrating cells. In several systems, it has been shown that the essential regulator of exocytosis is through the exocyst complex, mediated in part by PI(4,5)P2-binding. This review features the role of the CV complex in D. discoideum signaling with a focus on the role of PI(4,5)P2 in regulating CV exocytosis and localization. Many of the regulators of these processes are conserved during evolution, so the mechanisms controlling exocytosis and membrane trafficking in D. discoideum and mammalian cells will be discussed, highlighting their important functions in membrane trafficking and signaling in health and disease.
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Affiliation(s)
- Sana A. Fadil
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA, United States
- Department of Natural product, Faculty of Pharmacy, King Abdulaziz University, Saudia Arabia
| | - Chris Janetopoulos
- Department of Biological Sciences, University of the Sciences in Philadelphia, Philadelphia, PA, United States
- The Science Research Institute, Albright College, Reading, PA, United States
- The Department of Cell Biology at Johns Hopkins University School of Medicine, Baltimore, MD, United States
- *Correspondence: Chris Janetopoulos,
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13
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Ma X, Zhao X, Zhang H, Zhang Y, Sun S, Li Y, Long Z, Liu Y, Zhang X, Li R, Tan L, Jiang L, Zhu JK, Li L. MAG2 and MAL Regulate Vesicle Trafficking and Auxin Homeostasis With Functional Redundancy. FRONTIERS IN PLANT SCIENCE 2022; 13:849532. [PMID: 35371137 PMCID: PMC8966843 DOI: 10.3389/fpls.2022.849532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 01/24/2022] [Indexed: 06/14/2023]
Abstract
Auxin is a central phytohormone and controls almost all aspects of plant development and stress response. Auxin homeostasis is coordinately regulated by biosynthesis, catabolism, transport, conjugation, and deposition. Endoplasmic reticulum (ER)-localized MAIGO2 (MAG2) complex mediates tethering of arriving vesicles to the ER membrane, and it is crucial for ER export trafficking. Despite important regulatory roles of MAG2 in vesicle trafficking, the mag2 mutant had mild developmental abnormalities. MAG2 has one homolog protein, MAG2-Like (MAL), and the mal-1 mutant also had slight developmental phenotypes. In order to investigate MAG2 and MAL regulatory function in plant development, we generated the mag2-1 mal-1 double mutant. As expected, the double mutant exhibited serious developmental defects and more alteration in stress response compared with single mutants and wild type. Proteomic analysis revealed that signaling, metabolism, and stress response in mag2-1 mal-1 were affected, especially membrane trafficking and auxin biosynthesis, signaling, and transport. Biochemical and cell biological analysis indicated that the mag2-1 mal-1 double mutant had more serious defects in vesicle transport than the mag2-1 and mal-1 single mutants. The auxin distribution and abundance of auxin transporters were altered significantly in the mag2-1 and mal-1 single mutants and mag2-1 mal-1 double mutant. Our findings suggest that MAG2 and MAL regulate plant development and auxin homeostasis by controlling membrane trafficking, with functional redundancy.
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Affiliation(s)
- Xiaohui Ma
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Xiaonan Zhao
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
- Institute of Crop Science, Zhejiang University, Hangzhou, China
| | - Hailong Zhang
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Yiming Zhang
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Shanwen Sun
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Ying Li
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Zhengbiao Long
- Institute of Crop Science, Zhejiang University, Hangzhou, China
| | - Yuqi Liu
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Xiaomeng Zhang
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
| | - Rongxia Li
- Shanghai Center for Plant Stress Biology, Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Li Tan
- Shanghai Center for Plant Stress Biology, Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Lixi Jiang
- Institute of Crop Science, Zhejiang University, Hangzhou, China
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology, Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Lixin Li
- Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, College of Life Sciences, Ministry of Education, Northeast Forestry University, Harbin, China
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14
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Bai S, Hou W, Yao Y, Meng J, Wei Y, Hu F, Hu X, Wu J, Zhang N, Xu R, Tian F, Wang B, Liao H, Du Y, Fang H, He W, Liu Y, Shen B, Du J. Exocyst controls exosome biogenesis via Rab11a. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 27:535-546. [PMID: 35036064 PMCID: PMC8739877 DOI: 10.1016/j.omtn.2021.12.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 12/15/2021] [Indexed: 12/24/2022]
Abstract
Tumor cells actively release large quantities of exosomes, which pivotally participate in the regulation of cancer biology, including head and neck cancer (HNC). Exosome biogenesis and release are complex and elaborate processes that are considered to be similar to the process of exocyst-mediated vesicle delivery. By analyzing the expression of exocyst subunits and their role in patients with HNC, we aimed to identify exocyst and its functions in exosome biogenesis and investigate the molecular mechanisms underlying the regulation of exosome transport in HNC cells. We observed that exocysts were highly expressed in HNC cells and could promote exosome secretion in these cells. In addition, downregulation of exocyst expression inhibited HN4 cell proliferation by reducing exosome secretion. Interestingly, immunofluorescence and electron microscopy revealed the accumulation of multivesicular bodies (MVBs) after the knockdown of exocyst. Autophagy, the major pathway of exosome degradation, is not activated by this intracellular accumulation of MVBs, but these MVBs are consumed when autophagy is activated under the condition of cell starvation. Rab11a, a small GTPase that is involved in MVB fusion, also interacted with the exocyst. These findings suggest that the exocyst can regulate exosome biogenesis and participate in the malignant behavior of tumor cells.
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Affiliation(s)
- Suwen Bai
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Wenxuan Hou
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Yanheng Yao
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Jialin Meng
- Department of Urology, The First Affiliated Hospital of Anhui Medical University, Institute of Urology, Anhui Medical University, Anhui Province Key Laboratory of Genitourinary Diseases, Anhui Medical University, Hefei 230022, China
| | - Yuan Wei
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Fangfang Hu
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Xianyu Hu
- Department of General Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei 230022 Anhui, China
| | - Jing Wu
- Department of Otolaryngology, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China
| | - Ning Zhang
- Department of General Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei 230022 Anhui, China
| | - Ruihuan Xu
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Faqing Tian
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Benguo Wang
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Hailan Liao
- Longgang District People’s Hospital of Shenzhen & The Second Affiliated Hospital of The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
| | - Yinan Du
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Haoshu Fang
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Wei He
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Yehai Liu
- Department of Otolaryngology, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui Province, China
| | - Bing Shen
- School of Basic Medical Sciences, Anhui Medical University, 81 Meishan Road, Hefei 230032, Anhui, China
| | - Juan Du
- School of Medicine, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
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15
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Sulaiman N, Yaseen Hachim M, Khalique A, Mohammed AK, Al Heialy S, Taneera J. EXOC6 (Exocyst Complex Component 6) Is Associated with the Risk of Type 2 Diabetes and Pancreatic β-Cell Dysfunction. BIOLOGY 2022; 11:biology11030388. [PMID: 35336762 PMCID: PMC8945791 DOI: 10.3390/biology11030388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/25/2022] [Accepted: 02/25/2022] [Indexed: 11/16/2022]
Abstract
EXOC6 and EXOC6B (EXOC6/6B) components of the exocyst complex are involved in the secretory granule docking. Recently, EXOC6/6B were anticipated as a molecular link between dysfunctional pancreatic islets and ciliated lung epithelium, making diabetic patients more prone to severe SARS-CoV-2 complications. However, the exact role of EXOC6/6B in pancreatic β-cell function and risk of T2D is not fully understood. Herein, microarray and RNA-sequencing (RNA-seq) expression data demonstrated the expression of EXOC6/6B in human pancreatic islets. Expression of EXOC6/6B was not affected by diabetes status. Exploration of the using the translational human pancreatic islet genotype tissue-expression resource portal (TIGER) revealed three genetic variants (rs947591, rs2488071 and rs2488073) in the EXOC6 gene that were associated (p < 2.5 × 10−20) with the risk of T2D. Exoc6/6b silencing in rat pancreatic β-cells (INS1-832/13) impaired insulin secretion, insulin content, exocytosis machinery and glucose uptake without cytotoxic effect. A significant decrease in the expression Ins1, Ins1, Pdx1, Glut2 and Vamp2 was observed in Exoc6/6b-silenced cells at the mRNA and protein levels. However, NeuroD1, Gck and InsR were not influenced compared to the negative control. In conclusion, our data propose that EXOC6/6B are crucial regulators for insulin secretion and exocytosis machinery in β-cells. This study identified several genetic variants in EXOC6 associated with the risk of T2D. Therefore, EXOC6/6B could provide a new potential target for therapy development or early biomarkers for T2D.
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Affiliation(s)
- Nabil Sulaiman
- Department of Family Medicine, College of Medicine, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates;
| | - Mahmood Yaseen Hachim
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai P.O. Box 505055, United Arab Emirates; (M.Y.H.); (S.A.H.)
| | - Anila Khalique
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates; (A.K.); (A.K.M.)
| | - Abdul Khader Mohammed
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates; (A.K.); (A.K.M.)
| | - Saba Al Heialy
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai P.O. Box 505055, United Arab Emirates; (M.Y.H.); (S.A.H.)
| | - Jalal Taneera
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates; (A.K.); (A.K.M.)
- Department of Basic Sciences, College of Medicine, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
- Correspondence: ; Tel.: +971-6505-7743
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16
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Pallares RM, An DD, Hébert S, Faulkner D, Loguinov A, Proctor M, Villalobos JA, Bjornstad KA, Rosen CJ, Vulpe C, Abergel RJ. Delineating toxicity mechanisms associated with MRI contrast enhancement through a multidimensional toxicogenomic profiling of gadolinium. Mol Omics 2022; 18:237-248. [PMID: 35040455 DOI: 10.1039/d1mo00267h] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Gadolinium is a metal used in contrast agents for magnetic resonance imaging. Although gadolinium is widely used in clinical settings, many concerns regarding its toxicity and bioaccumulation after gadolinium-based contrast agent administration have been raised and published over the last decade. To date, most toxicological studies have focused on identifying acute effects following gadolinium exposure, rather than investigating associated toxicity mechanisms. In this study, we employ functional toxicogenomics to assess mechanistic interactions of gadolinium with Saccharomyces cerevisiae. Furthermore, we determine which mechanisms are conserved in humans, and their implications for diseases related to the use of gadolinium-based contrast agents in medicine. A homozygous deletion pool of 4291 strains were screened to identify biological functions and pathways disturbed by the metal. Gene ontology and pathway enrichment analyses showed endocytosis and vesicle-mediated transport as the main yeast response to gadolinium, while certain metabolic processes, such as glycosylation, were the primary disrupted functions after the metal treatments. Cluster and protein-protein interaction network analyses identified proteins mediating vesicle-mediated transport through the Golgi apparatus and the vacuole, and vesicle cargo exocytosis as key components to reduce the metal toxicity. Moreover, the metal seemed to induce cytotoxicity by disrupting the function of enzymes (e.g. transferases and proteases) and chaperones involved in metabolic processes. Several of the genes and proteins associated with gadolinium toxicity are conserved in humans, suggesting that they may participate in pathologies linked to gadolinium-based contrast agent exposures. We thereby discuss the potential role of these conserved genes and gene products in gadolinium-induced nephrogenic systemic fibrosis, and propose potential prophylactic strategies to prevent its adverse health effects.
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Affiliation(s)
- Roger M Pallares
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Dahlia D An
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Solène Hébert
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - David Faulkner
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Alex Loguinov
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Michael Proctor
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Jonathan A Villalobos
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Kathleen A Bjornstad
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Chris J Rosen
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
| | - Christopher Vulpe
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Rebecca J Abergel
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. .,Department of Nuclear Engineering, University of California, Berkeley, CA, 94720, USA
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17
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Mei K, Liu DA, Guo W. Determine the Function of the Exocyst in Vesicle Tethering by Ectopic Targeting. Methods Mol Biol 2022; 2473:65-77. [PMID: 35819759 DOI: 10.1007/978-1-0716-2209-4_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We describe an assay, in which ectopically targeting the exocyst subunit Sec3 to mitochondria is used to determine its role in tethering of post-Golgi vesicles to the plasma membrane. In the assay, we use a plasmid that encodes a fusion protein of the mitochondria protein Tom20 and Sec3 N-terminally tagged with the florescence protein mCherry, and coexpress the plasmid in yeast cells with CIT1-GFP, a marker protein of mitochondria. We then detect the colocalization between Sec3 and CIT1 and other exocyst subunits such as Sec5 on mitochondria using fluorescence microscopy. We further detect the colocalization between Sec3 and Sec4, a Rab protein and a marker of post-Golgi vesicles. Through this assay, we propose that the exocyst subunit Sec3 recruits the other exocyst subunits and secretory vesicles to a target membrane, suggesting that it plays a pivotal role in vesicle tethering. This approach is likely appropriate for studying other tethering complexes at their specific stages of trafficking and may also be used in other eukaryotic cells such as the cultured mammalian cells.
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Affiliation(s)
- Kunrong Mei
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, China
| | - Di-Ao Liu
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Wei Guo
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
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18
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Pallares RM, An DD, Hébert S, Faulkner D, Loguinov A, Proctor M, Villalobos JA, Bjornstad KA, Rosen CJ, Vulpe C, Abergel RJ. Multidimensional genome-wide screening in yeast provides mechanistic insights into europium toxicity. Metallomics 2021; 13:6409834. [PMID: 34694395 DOI: 10.1093/mtomcs/mfab061] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 10/19/2021] [Indexed: 11/13/2022]
Abstract
Europium is a lanthanide metal that is highly valued in optoelectronics. Even though europium is used in many commercial products, its toxicological profile has only been partially characterized, with most studies focusing on identifying lethal doses in different systems or bioaccumulation in vivo. This paper describes a genome-wide toxicogenomic study of europium in Saccharomyces cerevisiae, which shares many biological functions with humans. By using a multidimensional approach and functional and network analyses, we have identified a group of genes and proteins associated with the yeast responses to ameliorate metal toxicity, which include metal discharge paths through vesicle-mediated transport, paths to regulate biologically relevant cations, and processes to reduce metal-induced stress. Furthermore, the analyses indicated that europium promotes yeast toxicity by disrupting the function of chaperones and cochaperones, which have metal-binding sites. Several of the genes and proteins highlighted in our study have human orthologues, suggesting they may participate in europium-induced toxicity in humans. By identifying the endogenous targets of europium as well as the already existing paths that can decrease its toxicity, we can determine specific genes and proteins that may help to develop future therapeutic strategies.
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Affiliation(s)
- Roger M Pallares
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Dahlia D An
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Solène Hébert
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - David Faulkner
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Alex Loguinov
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA
| | - Michael Proctor
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA
| | - Jonathan A Villalobos
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Kathleen A Bjornstad
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Chris J Rosen
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Christopher Vulpe
- Center for Environmental and Human Toxicology, Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA
| | - Rebecca J Abergel
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Department of Nuclear Engineering, University of California, Berkeley, CA 94720, USA
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19
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Bustos Plonka F, Sosa LJ, Quiroga S. Sec3 exocyst component knockdown inhibits axonal formation and cortical neuronal migration during brain cortex development. J Neurochem 2021; 160:203-217. [PMID: 34862972 DOI: 10.1111/jnc.15554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 10/27/2021] [Accepted: 11/25/2021] [Indexed: 12/22/2022]
Abstract
Neurons are the largest known cells, with complex and highly polarized morphologies and consist of a cell body (soma), several dendrites, and a single axon. The establishment of polarity necessitates initial axonal outgrowth in concomitance with the addition of new membrane to the axon's plasmalemma. Axolemmal expansion occurs by exocytosis of plasmalemmal precursor vesicles primarily at the neuronal growth cone membrane. The multiprotein exocyst complex drives spatial location and specificity of vesicle fusion at plasma membrane. However, the specific participation of its different proteins on neuronal differentiation has not been fully established. In the present work we analyzed the role of Sec3, a prominent exocyst complex protein on neuronal differentiation. Using mice hippocampal primary cultures, we determined that Sec3 is expressed in neurons at early stages prior to neuronal polarization. Furthermore, we determined that silencing of Sec3 in mice hippocampal neurons in culture precluded polarization. Moreover, using in utero electroporation experiments, we determined that Sec3 knockdown affected cortical neurons migration and morphology during neocortex formation. Our results demonstrate that the exocyst complex protein Sec3 plays an important role in axon formation in neuronal differentiation and the migration of neuronal progenitors during cortex development.
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Affiliation(s)
- Florentyna Bustos Plonka
- Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Universidad Nacional de Córdoba y CIQUIBIC-CONICET, Córdoba, Argentina
| | - Lucas J Sosa
- Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Universidad Nacional de Córdoba y CIQUIBIC-CONICET, Córdoba, Argentina
| | - Santiago Quiroga
- Facultad de Ciencias Químicas, Departamento de Química Biológica Ranwel Caputto, Universidad Nacional de Córdoba y CIQUIBIC-CONICET, Córdoba, Argentina
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20
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Errachid A, Nohawica M, Wyganowska-Swiatkowska M. A comprehensive review of the influence of Epigallocatechin gallate on Sjögren's syndrome associated molecular regulators of exocytosis (Review). Biomed Rep 2021; 15:95. [PMID: 34631050 PMCID: PMC8493546 DOI: 10.3892/br.2021.1471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 06/25/2021] [Indexed: 12/03/2022] Open
Abstract
Sjögren's syndrome (SS) is an autoimmune disorder that affects the salivary glands, leading to reduced secretory functions and oral and ocular dryness. The salivary glands are composed of acinar cells that are responsible for the secretion and production of secretory granules, which contain salivary components, such as amylase, mucins and immunoglobulins. This secretion process involves secretory vesicle trafficking, docking, priming and membrane fusion. A failure during any of the steps in exocytosis in the salivary glands results in the altered secretion of saliva. Soluble N-ethylmaleimide-sensitive-factor attachment protein receptors, actin, tight junctions and aquaporin 5 all serve an important role in the trafficking regulation of secretory vesicles in the secretion of saliva via exocytosis. Alterations in the expression and distribution of these selected proteins leads to salivary gland dysfunction, including SS. Several studies have demonstrated that green tea polyphenols, most notably Epigallocatechin gallate (EGCG), possess both anti-inflammatory and anti-apoptotic properties in normal human cells. Molecular, cellular and animal studies have indicated that EGCG can provide protective effects against autoimmune and inflammatory reactions in salivary glands in diseases such as SS. The aim of the present article is to provide a comprehensive and up-to-date review on the possible therapeutic interactions between EGCG and the selected molecular mechanisms associated with SS.
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Affiliation(s)
- Abdelmounaim Errachid
- Department of Dental Surgery and Periodontology, Poznan University of Medicinal Sciences, 60-812 Poznań, Greater Poland, Poland.,Earth and Life Institute, University Catholique of Louvain, B-1348 Louvain-la-Neuve, Ottignies-Louvain-la-Neuve, Belgium
| | - Michal Nohawica
- Department of Dental Surgery and Periodontology, Poznan University of Medicinal Sciences, 60-812 Poznań, Greater Poland, Poland
| | - Marzena Wyganowska-Swiatkowska
- Department of Dental Surgery and Periodontology, Poznan University of Medicinal Sciences, 60-812 Poznań, Greater Poland, Poland
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21
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Zhu YQ, Qiu L, Liu LL, Luo L, Han XP, Zhai YH, Wang WJ, Ren MZ, Xing YD. Identification and Comprehensive Structural and Functional Analyses of the EXO70 Gene Family in Cotton. Genes (Basel) 2021; 12:genes12101594. [PMID: 34680988 PMCID: PMC8536163 DOI: 10.3390/genes12101594] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/30/2021] [Accepted: 10/02/2021] [Indexed: 11/24/2022] Open
Abstract
The EXO70 gene is a vital component of the exocytosis complex and participates in biological processes ranging from plant cell division to polar growth. There are many EXO70 genes in plants and their functions are extensive, but little is known about the EXO70 gene family in cotton. Here, we analyzed four cotton sequence databases, identified 165 EXO70 genes, and divided them into eight subgroups (EXO70A–EXO70H) based on their phylogenetic relationships. EXO70A had the most exons (≥11), whereas the other seven each had only one or two exons. Hence, EXO70A may have many important functions. The 84 EXO70 genes in Asian and upland cotton were expressed in the roots, stems, leaves, flowers, fibers, and/or ovules. Full-length GhEXO70A1-A cDNA was homologously cloned from upland cotton (Gossypium hirsutum, G. hirsutum). Subcellular analysis revealed that GhEXO70A1-A protein was localized to the plasma membrane. A yeast two-hybrid assay revealed that GhEXO70A1-A interacted with GhEXO84A, GhEXO84B, and GhEXO84C. GhEXO70A1-A silencing significantly altered over 4000 genes and changed several signaling pathways related to metabolism. Thus, the EXO70 gene plays critical roles in the physiological functions of cotton.
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Affiliation(s)
- Ya-Qian Zhu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Lu Qiu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- School of Life Sciences, Zhengzhou University, Zhengzhou 450001, China
| | - Lu-Lu Liu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Lei Luo
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Xin-Pei Han
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Yao-Hua Zhai
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Wen-Jing Wang
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
| | - Mao-Zhi Ren
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, China
- Correspondence: (M.-Z.R.); (Y.-D.X.)
| | - Ya-Di Xing
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, China; (Y.-Q.Z.); (L.Q.); (L.-L.L.); (L.L.); (X.-P.H.); (Y.-H.Z.); (W.-J.W.)
- Correspondence: (M.-Z.R.); (Y.-D.X.)
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22
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An SJ, Rivera-Molina F, Anneken A, Xi Z, McNellis B, Polejaev VI, Toomre D. An active tethering mechanism controls the fate of vesicles. Nat Commun 2021; 12:5434. [PMID: 34521845 PMCID: PMC8440521 DOI: 10.1038/s41467-021-25465-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 08/05/2021] [Indexed: 11/09/2022] Open
Abstract
Vesicle tethers are thought to underpin the efficiency of intracellular fusion by bridging vesicles to their target membranes. However, the interplay between tethering and fusion has remained enigmatic. Here, through optogenetic control of either a natural tether-the exocyst complex-or an artificial tether, we report that tethering regulates the mode of fusion. We find that vesicles mainly undergo kiss-and-run instead of full fusion in the absence of functional exocyst. Full fusion is rescued by optogenetically restoring exocyst function, in a manner likely dependent on the stoichiometry of tether engagement with the plasma membrane. In contrast, a passive artificial tether produces mostly kissing events, suggesting that kiss-and-run is the default mode of vesicle fusion. Optogenetic control of tethering further shows that fusion mode has physiological relevance since only full fusion could trigger lamellipodial expansion. These findings demonstrate that active coupling between tethering and fusion is critical for robust membrane merger.
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Affiliation(s)
- Seong J An
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Felix Rivera-Molina
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Alexander Anneken
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Zhiqun Xi
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Brian McNellis
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Vladimir I Polejaev
- International Science and Technology Center, Yale University School of Medicine, New Haven, CT, USA
| | - Derek Toomre
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA.
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23
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Sauvola CW, Littleton JT. SNARE Regulatory Proteins in Synaptic Vesicle Fusion and Recycling. Front Mol Neurosci 2021; 14:733138. [PMID: 34421538 PMCID: PMC8377282 DOI: 10.3389/fnmol.2021.733138] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/20/2021] [Indexed: 01/01/2023] Open
Abstract
Membrane fusion is a universal feature of eukaryotic protein trafficking and is mediated by the soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) family. SNARE proteins embedded in opposing membranes spontaneously assemble to drive membrane fusion and cargo exchange in vitro. Evolution has generated a diverse complement of SNARE regulatory proteins (SRPs) that ensure membrane fusion occurs at the right time and place in vivo. While a core set of SNAREs and SRPs are common to all eukaryotic cells, a specialized set of SRPs within neurons confer additional regulation to synaptic vesicle (SV) fusion. Neuronal communication is characterized by precise spatial and temporal control of SNARE dynamics within presynaptic subdomains specialized for neurotransmitter release. Action potential-elicited Ca2+ influx at these release sites triggers zippering of SNAREs embedded in the SV and plasma membrane to drive bilayer fusion and release of neurotransmitters that activate downstream targets. Here we discuss current models for how SRPs regulate SNARE dynamics and presynaptic output, emphasizing invertebrate genetic findings that advanced our understanding of SRP regulation of SV cycling.
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Affiliation(s)
- Chad W Sauvola
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, United States
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24
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Santana-Molina C, Gutierrez F, Devos DP. Homology and Modular Evolution of CATCHR at the Origin of the Eukaryotic Endomembrane System. Genome Biol Evol 2021; 13:6290715. [PMID: 34061181 PMCID: PMC8290106 DOI: 10.1093/gbe/evab125] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2021] [Indexed: 01/02/2023] Open
Abstract
The membrane trafficking is an essential process of eukaryotic cells, as it manages vesicular trafficking toward different parts of the cell. In this process, membrane fusions between vesicles and target membranes are mediated by several factors, including the multisubunit tethering complexes. One type of multisubunit tethering complex, the complexes associated with tethering containing helical rods (CATCHR), encompasses the exocyst, COG, GARP, and DSL1 complexes. The CATCHR share similarities at sequence, structural, and protein-complex organization level although their actual relationship is still poorly understood. In this study, we have re-evaluated CATCHR at different levels, demonstrating that gene duplications followed by neofunctionalization, were key for their origin. Our results, reveals that there are specific homology relationships and parallelism within and between the CATCHR suggesting that most of these complexes are composed by modular tetramers of four different kinds of proteins, three of them having a clear common origin. The extension of CATCHR family occurred concomitantly with the protein family expansions of their molecular partners, such as small GTPases and SNAREs, among others, and likely providing functional specificity. Our results provide novel insights into the structural organization and mechanism of action of CATCHR, with implications for the evolution of the endomembrane system of eukaryotes and promoting CATCHR as ideal candidates to study the evolution of multiprotein complexes.
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Affiliation(s)
- Carlos Santana-Molina
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas/Universidad Pablo de Olavide/Junta de Andalucía, Seville, Spain
| | - Fernando Gutierrez
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas/Universidad Pablo de Olavide/Junta de Andalucía, Seville, Spain.,Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Damien P Devos
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas/Universidad Pablo de Olavide/Junta de Andalucía, Seville, Spain
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25
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Isono K, Tsukimoto R, Iuchi S, Shinozawa A, Yotsui I, Sakata Y, Taji T. An ER-Golgi Tethering Factor SLOH4/MIP3 Is Involved in Long-Term Heat Tolerance of Arabidopsis. PLANT & CELL PHYSIOLOGY 2021; 62:272-279. [PMID: 33367686 DOI: 10.1093/pcp/pcaa157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 12/03/2020] [Indexed: 06/12/2023]
Abstract
Plants are often exposed not only to short-term (S-) heat stress but also to diurnal long-term (L-) heat stress over several consecutive days. To reveal the mechanisms underlying L-heat stress tolerance, we here used a forward genetic screen for sensitive to long-term heat (sloh) mutants and isolated sloh4. The mutant was hypersensitive to L-heat stress but not to S-heat stress. The causal gene of sloh4 was identical to MIP3 encoding a member of the MAIGO2 (MAG2) tethering complex, which is composed of the MAG2, MIP1, MIP2 and MIP3 subunits and is localized at the endoplasmic reticulum (ER) membrane. Although sloh4/mip3 was hypersensitive to L-heat stress, the sensitivity of the mag2-3 and mip1-1 mutants was similar to that of the wild type (WT). Under L-heat stress, the ER stress and the following unfolded protein response (UPR) were more pronounced in sloh4 than in the WT. Transcript levels of bZIP60-regulated UPR genes were strongly increased in sloh4 under L-heat stress. Two processes known to be mediated by INOSITOL REQUIRING ENZYME1 (IRE1) - accumulation of the spliced bZIP60 transcript and a decrease in the transcript levels of PR4 and PRX34, encoding secretory proteins - were observed in sloh4 in response to L-heat stress. These findings suggest that misfolded proteins generated in sloh4 under L-heat stress may be recognized by IRE1 but not by bZIP28, resulting in the initiation of the UPR via activated bZIP60. Therefore, it would be possible that only MIP3 in the MAG2 complex has an additional function in L-heat tolerance, which is not related to the ER-Golgi vesicle tethering.
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Affiliation(s)
- Kazuho Isono
- Department of Bioscience, Tokyo University of Agriculture, Tokyo, 156-8502 Japan
| | - Ryo Tsukimoto
- Department of Bioscience, Tokyo University of Agriculture, Tokyo, 156-8502 Japan
| | - Satoshi Iuchi
- RIKEN BioResource Research Center, Ibaraki, 305-0074 Japan
| | - Akihisa Shinozawa
- NODAI Genome Research Center (NGRC), Tokyo University of Agriculture, Tokyo, 156-8502 Japan
| | - Izumi Yotsui
- Department of Bioscience, Tokyo University of Agriculture, Tokyo, 156-8502 Japan
| | - Yoichi Sakata
- Department of Bioscience, Tokyo University of Agriculture, Tokyo, 156-8502 Japan
| | - Teruaki Taji
- Department of Bioscience, Tokyo University of Agriculture, Tokyo, 156-8502 Japan
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26
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Kyriakoudi S, Drousiotou A, Petrou PP. When the Balance Tips: Dysregulation of Mitochondrial Dynamics as a Culprit in Disease. Int J Mol Sci 2021; 22:ijms22094617. [PMID: 33924849 PMCID: PMC8124286 DOI: 10.3390/ijms22094617] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/23/2021] [Accepted: 04/25/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are dynamic organelles, the morphology of which is tightly linked to their functions. The interplay between the coordinated events of fusion and fission that are collectively described as mitochondrial dynamics regulates mitochondrial morphology and adjusts mitochondrial function. Over the last few years, accruing evidence established a connection between dysregulated mitochondrial dynamics and disease development and progression. Defects in key components of the machinery mediating mitochondrial fusion and fission have been linked to a wide range of pathological conditions, such as insulin resistance and obesity, neurodegenerative diseases and cancer. Here, we provide an update on the molecular mechanisms promoting mitochondrial fusion and fission in mammals and discuss the emerging association of disturbed mitochondrial dynamics with human disease.
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Affiliation(s)
- Styliana Kyriakoudi
- Department of Biochemical Genetics, The Cyprus Institute of Neurology and Genetics, P.O. Box 23462, Nicosia 1683, Cyprus; (S.K.); (A.D.)
| | - Anthi Drousiotou
- Department of Biochemical Genetics, The Cyprus Institute of Neurology and Genetics, P.O. Box 23462, Nicosia 1683, Cyprus; (S.K.); (A.D.)
- Cyprus School of Molecular Medicine, P.O. Box 23462, Nicosia 1683, Cyprus
| | - Petros P. Petrou
- Department of Biochemical Genetics, The Cyprus Institute of Neurology and Genetics, P.O. Box 23462, Nicosia 1683, Cyprus; (S.K.); (A.D.)
- Cyprus School of Molecular Medicine, P.O. Box 23462, Nicosia 1683, Cyprus
- Correspondence:
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27
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Dautt-Castro M, Rosendo-Vargas M, Casas-Flores S. The Small GTPases in Fungal Signaling Conservation and Function. Cells 2021; 10:cells10051039. [PMID: 33924947 PMCID: PMC8146680 DOI: 10.3390/cells10051039] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 12/28/2022] Open
Abstract
Monomeric GTPases, which belong to the Ras superfamily, are small proteins involved in many biological processes. They are fine-tuned regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). Several families have been identified in organisms from different kingdoms. Overall, the most studied families are Ras, Rho, Rab, Ran, Arf, and Miro. Recently, a new family named Big Ras GTPases was reported. As a general rule, the proteins of all families have five characteristic motifs (G1–G5), and some specific features for each family have been described. Here, we present an exhaustive analysis of these small GTPase families in fungi, using 56 different genomes belonging to different phyla. For this purpose, we used distinct approaches such as phylogenetics and sequences analysis. The main functions described for monomeric GTPases in fungi include morphogenesis, secondary metabolism, vesicle trafficking, and virulence, which are discussed here. Their participation during fungus–plant interactions is reviewed as well.
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28
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Nam SE, Cheung YWS, Nguyen TN, Gong M, Chan S, Lazarou M, Yip CK. Insights on autophagosome-lysosome tethering from structural and biochemical characterization of human autophagy factor EPG5. Commun Biol 2021; 4:291. [PMID: 33674710 PMCID: PMC7935953 DOI: 10.1038/s42003-021-01830-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 02/10/2021] [Indexed: 12/17/2022] Open
Abstract
Pivotal to the maintenance of cellular homeostasis, macroautophagy (hereafter autophagy) is an evolutionarily conserved degradation system that involves sequestration of cytoplasmic material into the double-membrane autophagosome and targeting of this transport vesicle to the lysosome/late endosome for degradation. EPG5 is a large-sized metazoan protein proposed to serve as a tethering factor to enforce autophagosome–lysosome/late endosome fusion specificity, and its deficiency causes a severe multisystem disorder known as Vici syndrome. Here, we show that human EPG5 (hEPG5) adopts an extended “shepherd’s staff” architecture. We find that hEPG5 binds preferentially to members of the GABARAP subfamily of human ATG8 proteins critical to autophagosome–lysosome fusion. The hEPG5–GABARAPs interaction, which is mediated by tandem LIR motifs that exhibit differential affinities, is required for hEPG5 recruitment to mitochondria during PINK1/Parkin-dependent mitophagy. Lastly, we find that the Vici syndrome mutation Gln336Arg does not affect the hEPG5’s overall stability nor its ability to engage in interaction with the GABARAPs. Collectively, results from our studies reveal new insights into how hEPG5 recognizes mature autophagosome and establish a platform for examining the molecular effects of Vici syndrome disease mutations on hEPG5. Nam and Cheung et al. describe the structural and biochemical characterization of human autophagy factor EPG5 that functions in autophagosome–lysosome tethering. They show that hEPG5 adopts an extended shepherd’s staff architecture, binds preferentially to GABARAP proteins, and is recruited to mitochondria during mitophagy.
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Affiliation(s)
- Sung-Eun Nam
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
| | - Yiu Wing Sunny Cheung
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
| | - Thanh Ngoc Nguyen
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Michael Gong
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
| | - Samuel Chan
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada
| | - Michael Lazarou
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Calvin K Yip
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC, Canada.
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29
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Travis SM, DAmico K, Yu IM, McMahon C, Hamid S, Ramirez-Arellano G, Jeffrey PD, Hughson FM. Structural basis for the binding of SNAREs to the multisubunit tethering complex Dsl1. J Biol Chem 2020; 295:10125-10135. [PMID: 32409579 DOI: 10.1074/jbc.ra120.013654] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/01/2020] [Indexed: 01/02/2023] Open
Abstract
Multisubunit-tethering complexes (MTCs) are large (250 to >750 kDa), conserved macromolecular machines that are essential for soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated membrane fusion in all eukaryotes. MTCs are thought to organize membrane trafficking by mediating the initial long-range interaction between a vesicle and its target membrane and promoting the formation of membrane-bridging SNARE complexes. Previously, we reported the structure of the yeast Dsl1 complex, the simplest known MTC, which is essential for coat protein I (COPI) mediated transport from the Golgi to the endoplasmic reticulum (ER). This structure suggests how the Dsl1 complex might tether a vesicle to its target membrane by binding at one end to the COPI coat and at the other to ER-associated SNAREs. Here, we used X-ray crystallography to investigate these Dsl1-SNARE interactions in greater detail. The Dsl1 complex comprises three subunits that together form a two-legged structure with a central hinge. We found that distal regions of each leg bind N-terminal Habc domains of the ER SNAREs Sec20 (a Qb-SNARE) and Use1 (a Qc-SNARE). The observed binding modes appear to anchor the Dsl1 complex to the ER target membrane while simultaneously ensuring that both SNAREs are in open conformations, with their SNARE motifs available for assembly. The proximity of the two SNARE motifs, and therefore their ability to enter the same SNARE complex, will depend on the relative orientation of the two Dsl1 legs. These results underscore the critical roles of SNARE N-terminal domains in mediating interactions with other elements of the vesicle docking and fusion machinery.
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Affiliation(s)
- Sophie M Travis
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Kevin DAmico
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - I-Mei Yu
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Conor McMahon
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Safraz Hamid
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | | | - Philip D Jeffrey
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
| | - Frederick M Hughson
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA
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30
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Wang S, Crisman L, Miller J, Datta I, Gulbranson DR, Tian Y, Yin Q, Yu H, Shen J. Inducible Exoc7/Exo70 knockout reveals a critical role of the exocyst in insulin-regulated GLUT4 exocytosis. J Biol Chem 2019; 294:19988-19996. [PMID: 31740584 PMCID: PMC6937574 DOI: 10.1074/jbc.ra119.010821] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/13/2019] [Indexed: 12/20/2022] Open
Abstract
Insulin promotes glucose uptake by triggering the translocation of glucose transporter type 4 (GLUT4) from intracellular vesicles to the plasma membrane through exocytosis. GLUT4 exocytosis is a vesicle fusion event involving fusion of GLUT4-containing vesicles with the plasma membrane. For GLUT4 vesicle fusion to occur, GLUT4 vesicles must first be tethered to the plasma membrane. A key tethering factor in exocytosis is a heterooctameric protein complex called the exocyst. The role of the exocyst in GLUT4 exocytosis, however, remains incompletely understood. Here we first systematically analyzed data from a genome-scale CRISPR screen in HeLa cells that targeted virtually all known genes in the human genome, including 12 exocyst genes. The screen recovered only a subset of the exocyst genes, including exocyst complex component 7 (Exoc7/Exo70). Other exocyst genes, however, were not isolated in the screen, likely because of functional redundancy. Our findings suggest that selection of an appropriate exocyst gene is critical for genetic studies of exocyst functions. Next we developed an inducible adipocyte genome editing system that enabled Exoc7 gene deletion in adipocytes without interfering with adipocyte differentiation. We observed that insulin-stimulated GLUT4 exocytosis was markedly inhibited in Exoc7 KO adipocytes. Insulin signaling, however, remained intact in these KO cells. These results indicate that the exocyst plays a critical role in insulin-stimulated GLUT4 exocytosis in adipocytes. We propose that the strategy outlined in this work could be instrumental in genetically dissecting other membrane-trafficking pathways in adipocytes.
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Affiliation(s)
- Shifeng Wang
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
- Department of Chinese Medicine Information Science, Beijing University of Chinese Medicine, Beijing 102488, China
| | - Lauren Crisman
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Jessica Miller
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Ishara Datta
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Daniel R Gulbranson
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
| | - Yuan Tian
- Department of Biological Sciences and Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306
| | - Qian Yin
- Department of Biological Sciences and Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306
| | - Haijia Yu
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Jingshi Shen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Colorado 80309
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31
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Blackburn JB, D'Souza Z, Lupashin VV. Maintaining order: COG complex controls Golgi trafficking, processing, and sorting. FEBS Lett 2019; 593:2466-2487. [PMID: 31381138 PMCID: PMC6771879 DOI: 10.1002/1873-3468.13570] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 12/31/2022]
Abstract
The conserved oligomeric Golgi (COG) complex, a multisubunit tethering complex of the CATCHR (complexes associated with tethering containing helical rods) family, controls membrane trafficking and ensures Golgi homeostasis by orchestrating retrograde vesicle targeting within the Golgi. In humans, COG defects lead to severe multisystemic diseases known as COG‐congenital disorders of glycosylation (COG‐CDG). The COG complex both physically and functionally interacts with all classes of molecules maintaining intra‐Golgi trafficking, namely SNAREs, SNARE‐interacting proteins, Rabs, coiled‐coil tethers, and vesicular coats. Here, we review our current knowledge of COG‐related trafficking and glycosylation defects in humans and model organisms, and analyze possible scenarios for the molecular mechanism of the COG orchestrated vesicle targeting.
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Affiliation(s)
- Jessica B Blackburn
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Zinia D'Souza
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Vladimir V Lupashin
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
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32
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Boehm C, Field MC. Evolution of late steps in exocytosis: conservation, specialization. Wellcome Open Res 2019; 4:112. [DOI: 10.12688/wellcomeopenres.15142.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2019] [Indexed: 11/20/2022] Open
Abstract
Background:The eukaryotic endomembrane system likely aroseviaparalogous expansion of genes encoding proteins specifying organelle identity, coat complexes and government of fusion specificity. While the majority of these gene families were established by the time of the last eukaryotic common ancestor (LECA), subsequent evolutionary events molded these systems, likely reflecting adaptations retained for increased fitness. As well as sequence evolution, these adaptations include loss of otherwise canonical subunits, emergence of lineage-specific proteins and paralog expansion. The exocyst complex is involved in late exocytosis, and possibly additional pathways, and is a member of the complexes associated with tethering containing helical rods (CATCHR) tethering complex family, which includes conserved oligomeric Golgi (COG), homotypic fusion and vacuole protein sorting (HOPS), class C core vacuole/endosome tethering (CORVET) and others. The exocyst is integrated into a complex GTPase signaling network in animals, fungi and other lineages. Prompted by discovery of Exo99, a non-canonical subunit in the excavate protistTrypanosoma brucei,and significantly increased genome sequence data, we examined evolution of the exocyst.Methods:We examined evolution of the exocyst by comparative genomics, phylogenetics and structure prediction.Results:The exocyst is highly conserved, but with substantial losses of subunits in the Apicomplexa and expansions in Streptophyta plants and Metazoa. Significantly, few taxa retain a partial complex, suggesting that, in the main, all subunits are required for functionality. Further, the ninth exocyst subunit Exo99 is specific to the Euglenozoa with a distinct architecture compared to the other subunits and which possibly represents a coat system.Conclusions:These data reveal a remarkable degree of evolutionary flexibility within the exocyst complex, suggesting significant diversity in exocytosis mechanisms.
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33
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Duan Y, Guo Q, Zhang T, Meng Y, Sun D, Luo G, Liu Y. Cyclin-dependent kinase-mediated phosphorylation of the exocyst subunit Exo84 in late G 1 phase suppresses exocytic secretion and cell growth in yeast. J Biol Chem 2019; 294:11323-11332. [PMID: 31171719 DOI: 10.1074/jbc.ra119.008591] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 05/10/2019] [Indexed: 12/22/2022] Open
Abstract
In eukaryotic cells, the growth rate is strictly regulated for proper progression of the cell cycle. In the budding yeast Saccharomyces cerevisiae, it was previously shown that cell growth dramatically slows down when the cells start budding at the G1/S transition. However, the molecular mechanism for this G1/S-associated growth arrest is unclear. In this study, using exocytic secretion, cyclin-dependent kinase (CDK) assay, immunoprecipitation, and microscopy, we demonstrate that the exocyst subunit Exo84, which is known to be phosphorylated in mitosis, can also be phosphorylated directly by Cdk1 in the late G1 phase. Of note, we found that the Cdk1-mediated Exo84 phosphorylation impairs exocytic secretion in the late G1 phase. Using conditional cdc mutants and phosphodeficient and phosphomimetic exo84 mutants, we further observed that Cdk1-phosphoryated Exo84 inhibits the exocyst complex assembly, exocytic secretion, and cell growth, which may be important for proper execution of the G1/S-phase transition before commitment to a complete cell cycle. Our results suggest that the direct Cdk1-mediated regulation of the exocyst complex critically contributes to the coordination of cell growth and cell cycle progression.
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Affiliation(s)
- Yuran Duan
- Department of Biochemistry and Molecular Biology, China Medical University, Shenyang 110122, China
| | - Qingguo Guo
- Department of Biochemistry and Molecular Biology, China Medical University, Shenyang 110122, China
| | - Tianrui Zhang
- Department of Biochemistry and Molecular Biology, China Medical University, Shenyang 110122, China
| | - Yuan Meng
- Department of Biochemistry and Molecular Biology, China Medical University, Shenyang 110122, China
| | - Dong Sun
- Institute of Translational Medicine, China Medical University, Shenyang 110122, China
| | - Guangzuo Luo
- Institute of Translational Medicine, China Medical University, Shenyang 110122, China
| | - Ying Liu
- Department of Biochemistry and Molecular Biology, China Medical University, Shenyang 110122, China
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34
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Gillingham AK, Munro S. Transport carrier tethering - how vesicles are captured by organelles. Curr Opin Cell Biol 2019; 59:140-146. [PMID: 31154044 DOI: 10.1016/j.ceb.2019.04.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 04/16/2019] [Accepted: 04/24/2019] [Indexed: 12/20/2022]
Abstract
All cells contain numerous membrane-bound organelles that carry out specific functions. These compartments do not, however, act in isolation. Some are in direct contact via membrane contact sites, while others exchange material via specific vesicles or tubular carriers laden with cargo. The term tethering in the context of this review is used to describe the primary recognition and docking of transport carriers with acceptor organelles that occurs before SNARE engagement and membrane fusion. However, it is important to note that other tethering events occur, for example, between organelles in direct contact, which do not lead to fusion.
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Affiliation(s)
- Alison K Gillingham
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
| | - Sean Munro
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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35
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Ungermann C, Kümmel D. Structure of membrane tethers and their role in fusion. Traffic 2019; 20:479-490. [DOI: 10.1111/tra.12655] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/26/2019] [Accepted: 05/03/2019] [Indexed: 12/27/2022]
Affiliation(s)
- Christian Ungermann
- Biochemistry Section, Department of Biology/ChemistryUniversity of Osnabrück Osnabrück Germany
- Center for Cellular Nanoanalytics (CellNanOs)University of Osnabrück Osnabrück Germany
| | - Daniel Kümmel
- Biochemistry & Structural Biology Section, Institute of BiochemistryUniversity of Münster Münster Germany
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36
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Molecular mechanisms of contractile-ring constriction and membrane trafficking in cytokinesis. Biophys Rev 2018; 10:1649-1666. [PMID: 30448943 DOI: 10.1007/s12551-018-0479-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/06/2018] [Indexed: 12/14/2022] Open
Abstract
In this review, we discuss the molecular mechanisms of cytokinesis from plants to humans, with a focus on contribution of membrane trafficking to cytokinesis. Selection of the division site in fungi, metazoans, and plants is reviewed, as well as the assembly and constriction of a contractile ring in fungi and metazoans. We also provide an introduction to exocytosis and endocytosis, and discuss how they contribute to successful cytokinesis in eukaryotic cells. The conservation in the coordination of membrane deposition and cytoskeleton during cytokinesis in fungi, metazoans, and plants is highlighted.
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37
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Suzuki A, Iwata J. Molecular Regulatory Mechanism of Exocytosis in the Salivary Glands. Int J Mol Sci 2018; 19:E3208. [PMID: 30336591 PMCID: PMC6214078 DOI: 10.3390/ijms19103208] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 10/10/2018] [Accepted: 10/11/2018] [Indexed: 12/12/2022] Open
Abstract
Every day, salivary glands produce about 0.5 to 1.5 L of saliva, which contains salivary proteins that are essential for oral health. The contents of saliva, 0.3% proteins (1.5 to 4.5 g) in fluid, help prevent oral infections, provide lubrication, aid digestion, and maintain oral health. Acinar cells in the lobular salivary glands secrete prepackaged secretory granules that contain salivary components such as amylase, mucins, and immunoglobulins. Despite the important physiological functions of salivary proteins, we know very little about the regulatory mechanisms of their secretion via exocytosis, which is a process essential for the secretion of functional proteins, not only in salivary glands, but also in other secretory organs, including lacrimal and mammary glands, the pancreas, and prostate. In this review, we discuss recent findings that elucidate exocytosis by exocrine glands, especially focusing on the salivary glands, in physiological and pathological conditions.
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Affiliation(s)
- Akiko Suzuki
- Department of Diagnostic & Biomedical Sciences, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Center for Craniofacial Research, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
| | - Junichi Iwata
- Department of Diagnostic & Biomedical Sciences, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Center for Craniofacial Research, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Program of Biochemistry and Cell Biology, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.
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38
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Sacher M, Shahrzad N, Kamel H, Milev MP. TRAPPopathies: An emerging set of disorders linked to variations in the genes encoding transport protein particle (TRAPP)-associated proteins. Traffic 2018; 20:5-26. [PMID: 30152084 DOI: 10.1111/tra.12615] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 08/23/2018] [Accepted: 08/26/2018] [Indexed: 02/06/2023]
Abstract
The movement of proteins between cellular compartments requires the orchestrated actions of many factors including Rab family GTPases, Soluble NSF Attachment protein REceptors (SNAREs) and so-called tethering factors. One such tethering factor is called TRAnsport Protein Particle (TRAPP), and in humans, TRAPP proteins are distributed into two related complexes called TRAPP II and III. Although thought to act as a single unit within the complex, in the past few years it has become evident that some TRAPP proteins function independently of the complex. Consistent with this, variations in the genes encoding these proteins result in a spectrum of human diseases with diverse, but partially overlapping, phenotypes. This contrasts with other tethering factors such as COG, where variations in the genes that encode its subunits all result in an identical phenotype. In this review, we present an up-to-date summary of all the known disease-related variations of genes encoding TRAPP-associated proteins and the disorders linked to these variations which we now call TRAPPopathies.
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Affiliation(s)
- Michael Sacher
- Department of Biology, Concordia University, Montreal, Quebec, Canada.,Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
| | - Nassim Shahrzad
- Department of Medicine, University of California, San Francisco, California
| | - Hiba Kamel
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Miroslav P Milev
- Department of Biology, Concordia University, Montreal, Quebec, Canada
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39
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Lepore DM, Martínez-Núñez L, Munson M. Exposing the Elusive Exocyst Structure. Trends Biochem Sci 2018; 43:714-725. [PMID: 30055895 PMCID: PMC6108956 DOI: 10.1016/j.tibs.2018.06.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 06/18/2018] [Accepted: 06/29/2018] [Indexed: 11/18/2022]
Abstract
A major challenge for a molecular understanding of membrane trafficking has been the elucidation of high-resolution structures of large, multisubunit tethering complexes that spatially and temporally control intracellular membrane fusion. Exocyst is a large hetero-octameric protein complex proposed to tether secretory vesicles at the plasma membrane to provide quality control of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-mediated membrane fusion. Breakthroughs in methodologies, including sample preparation, biochemical characterization, fluorescence microscopy, and single-particle cryoelectron microscopy, are providing critical insights into the structure and function of the exocyst. These studies now pose more questions than answers for understanding fundamental functional mechanisms, and they open wide the door for future studies to elucidate interactions with protein and membrane partners, potential conformational changes, and molecular insights into tethering reactions.
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Affiliation(s)
- Dante M Lepore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Leonora Martínez-Núñez
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Mary Munson
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA.
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40
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Zhao X, Guo X, Tang X, Zhang H, Wang M, Kong Y, Zhang X, Zhao Z, Lv M, Li L. Misregulation of ER-Golgi Vesicle Transport Induces ER Stress and Affects Seed Vigor and Stress Response. FRONTIERS IN PLANT SCIENCE 2018; 9:658. [PMID: 29868102 PMCID: PMC5968616 DOI: 10.3389/fpls.2018.00658] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/30/2018] [Indexed: 05/20/2023]
Abstract
Seeds of higher plants accumulate numerous storage proteins to use as nitrogen resources for early plant development. Seed storage proteins (SSPs) are synthesized as large precursors on the rough endoplasmic reticulum (rER), and are delivered to protein storage vacuoles (PSVs) via vesicle transport, where they are processed to mature forms. We previously identified an Arabidopsis ER-localized tethering complex, MAG2 complex, which might be involved in Golgi to ER retrograde transport. The MAG2 complex is composed of 4 subunits, MAG2, MIP1, MIP2, and MIP3. Mutants with defective alleles for these subunits accumulated SSP precursors inside the ER lumen. Here, we report that the mag2-1 mip3-1 and mip2-1 mip3-1 double mutant have more serious vesicle transport defects than the mag2-1, mip2-1, and mip3-1 single mutants, since they accumulate more SSP precursors than the corresponding single mutants, and ER stress is more severe than the single mutants. The mag2-1 mip3-1 and mip2-1 mip3-1 double mutants show growth and developmental defects rather than the single mutants. Both single and double mutant seeds are found to have lower protein content and decreased germinating vigor than wild type seeds. All the mutants are sensitive to abscisic acid (ABA) and salt stress, and exhibit alteration in ABA signaling pathway. Our study clarified that ER-Golgi vesicle transport affects seed vigor through controlling seed protein quality and content, as well as plant response to environmental stress via influencing ABA signaling pathway.
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Affiliation(s)
- Xiaonan Zhao
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
| | - Xiufen Guo
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
| | - Xiaofei Tang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
- Institute of Soybean Research, Heilongjiang Provincial Academy of Agricultural Sciences, Harbin, China
| | - Hailong Zhang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
| | - Mingjing Wang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
| | - Yun Kong
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
| | - Xiaomeng Zhang
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
| | - Zhenjie Zhao
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
| | - Min Lv
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
| | - Lixin Li
- Key Laboratory of Saline-alkali Vegetation Ecology Restoration, Ministry of Education, Alkali Soil Natural Environmental Science Center, Northeast Forestry University, Harbin, China
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41
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Climer LK, Pokrovskaya ID, Blackburn JB, Lupashin VV. Membrane detachment is not essential for COG complex function. Mol Biol Cell 2018; 29:964-974. [PMID: 29467253 PMCID: PMC5896934 DOI: 10.1091/mbc.e17-11-0694] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
COG is a multisubunit vesicle tethering complex in the Golgi. We demonstrate that both COG subcomplexes can be permanently attached to Golgi membranes and that major COG functions do not require cycling between the membrane and cytosol. The conserved oligomeric Golgi (COG) complex is a vesicle tether of the “complexes associated with tethering containing helical rods” family, which functions on the cytoplasmic side of Golgi. It is currently unknown whether COG function, or function of any multisubunit vesicular tether, depends on cycling between the membrane and cytosol. Therefore, we permanently anchored key subunits of COG subcomplexes (COG4, COG7, and COG8) to Golgi membranes using transmembrane protein TMEM115 (TMEM-COG). All TMEM-COG subunits tested were Golgi localized, integrated into the COG complex, and stabilized membrane association of endogenous subunits. Interestingly, TMEM-COG4 and TMEM-COG7 equally rescued COG function in organization of Golgi markers, glycosylation, and abundance of COG-sensitive proteins. In contrast, TMEM-COG8 was not as effective, indicating that N-terminal attachment of COG8 interfered with overall COG structure and function, and none of the TMEM-COG subunits rescued the abnormal Golgi architecture caused by COG knockout. Collectively, these data indicate that both subcomplexes of the COG complex can perform most of COG function when permanently attached to membranes and that the cytosolic pool of COG is not completely essential to COG function.
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Affiliation(s)
- Leslie K Climer
- College of Medicine, Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | - Irina D Pokrovskaya
- College of Medicine, Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | - Jessica B Blackburn
- College of Medicine, Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | - Vladimir V Lupashin
- College of Medicine, Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR 72205
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42
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Giantin is required for coordinated production of aggrecan, link protein and type XI collagen during chondrogenesis. Biochem Biophys Res Commun 2018; 499:459-465. [PMID: 29577904 DOI: 10.1016/j.bbrc.2018.03.163] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 03/21/2018] [Indexed: 12/12/2022]
Abstract
Extracellular matrix (ECM) constitutes a proper micro-environment for cell proliferation, migration and differentiation, as well as playing pivotal roles in developmental processes including endochondral ossification. Cartilage ECM is mainly composed of fibrous proteins, including collagen, proteoglycan, and hyaluronan. Because almost all ECM components are transported by intracellular vesicular transport systems, molecules that mediate vesicle transport are also important for endochondral ossification. Giantin, encoded by the Golgb1 gene, is a tethering factor for coatomer 1 (COPI) vesicles and functions in the cis-medial Golgi compartments. An insertion mutation in the Golgb1 gene, resulting in a lack of giantin protein expression, has been detected in ocd/ocd rats that exhibit a pleiotropic phenotype including osteochondrodysplasia. To reveal the function of giantin in chondrogenesis, the present study assessed the effects of loss of giantin expression on cartilage ECM and Golgi morphology. Giantin was expressed in normal, but not in ocd/ocd, chondrocytes in the epiphyseal areas of embryonic femurs, whereas GM130 was expressed in both normal and ocd/ocd chondrocytes. The staining intensities of safranin O and azan (aniline blue) were reduced and enhanced, respectively, in epiphyseal cartilage of ocd/ocd femurs. Immunostaining showed that levels of type II collagen and fibronectin were comparable in normal and ocd/ocd cartilage. Levels of type XI collagen were higher, while levels of aggrecan, link protein and hyaluronan were lower, in ocd/ocd than in normal cartilage, although semi-quantitative RT-PCR showed similar levels of type XI collagen, aggrecan and link protein mRNAs in normal and ocd/ocd cartilage. Isolated chondrocytes of ocd/ocd and normal rats showed similar immunostaining patterns for cis-, medial-, and trans-Golgi marker proteins, whereas monolayers of ocd/ocd chondrocytes showed reduced levels of aggrecan and link protein and increased level of type XI collagen in spite of similar transcripts levels. These findings suggest that giantin plays a pivotal role in coordinated production of aggrecan, link protein and type XI collagen in chondrocytes, and that loss of giantin causes osteochondrodysplasia with disturbance of these ECM components.
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43
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Mei K, Li Y, Wang S, Shao G, Wang J, Ding Y, Luo G, Yue P, Liu JJ, Wang X, Dong MQ, Wang HW, Guo W. Cryo-EM structure of the exocyst complex. Nat Struct Mol Biol 2018; 25:139-146. [PMID: 29335562 PMCID: PMC5971111 DOI: 10.1038/s41594-017-0016-2] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 12/07/2017] [Indexed: 12/22/2022]
Abstract
The exocyst is an evolutionarily conserved octameric protein complex that mediates the tethering of post-Golgi secretory vesicles to the plasma membrane during exocytosis and is implicated in many cellular processes such as cell polarization, cytokinesis, ciliogenesis and tumor invasion. Using cryo-EM and chemical cross-linking MS (CXMS), we solved the structure of the Saccharomyces cerevisiae exocyst complex at an average resolution of 4.4 Å. Our model revealed the architecture of the exocyst and led to the identification of the helical bundles that mediate the assembly of the complex at its core. Sequence analysis suggests that these regions are evolutionarily conserved across eukaryotic systems. Additional cell biological data suggest a mechanism for exocyst assembly that leads to vesicle tethering at the plasma membrane.
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Affiliation(s)
- Kunrong Mei
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Yan Li
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China.,Tsinghua-Peking Joint Center for Life Sciences, Beijing, China
| | - Shaoxiao Wang
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Guangcan Shao
- National Institute of Biological Sciences, Beijing, China
| | - Jia Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China.,Tsinghua-Peking Joint Center for Life Sciences, Beijing, China
| | - Yuehe Ding
- National Institute of Biological Sciences, Beijing, China
| | - Guangzuo Luo
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Peng Yue
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Jun-Jie Liu
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Xinquan Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing, China
| | - Hong-Wei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua University, Beijing, China. .,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, China. .,School of Life Sciences, Tsinghua University, Beijing, China. .,Tsinghua-Peking Joint Center for Life Sciences, Beijing, China.
| | - Wei Guo
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA.
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44
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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: 1.7] [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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45
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Witkos TM, Lowe M. Recognition and tethering of transport vesicles at the Golgi apparatus. Curr Opin Cell Biol 2017; 47:16-23. [DOI: 10.1016/j.ceb.2017.02.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 02/02/2017] [Accepted: 02/08/2017] [Indexed: 12/15/2022]
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46
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Ramadass M, Catz SD. Molecular mechanisms regulating secretory organelles and endosomes in neutrophils and their implications for inflammation. Immunol Rev 2017; 273:249-65. [PMID: 27558339 DOI: 10.1111/imr.12452] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Neutrophils constitute the first line of cellular defense against invading microorganisms and modulate the subsequent innate and adaptive immune responses. In order to execute a rapid and precise response to infections, neutrophils rely on preformed effector molecules stored in a variety of intracellular granules. Neutrophil granules contain microbicidal factors, the membrane-bound components of the respiratory burst oxidase, membrane-bound adhesion molecules, and receptors that facilitate the execution of all neutrophil functions including adhesion, transmigration, phagocytosis, degranulation, and neutrophil extracellular trap formation. The rapid mobilization of intracellular organelles is regulated by vesicular trafficking mechanisms controlled by effector molecules that include small GTPases and their interacting proteins. In this review, we focus on recent discoveries of mechanistic processes that are at center stage of the regulation of neutrophil function, highlighting the discrete and selective pathways controlled by trafficking modulators. In particular, we describe novel pathways controlled by the Rab27a effectors JFC1 and Munc13-4 in the regulation of degranulation, reactive oxygen species and neutrophil extracellular trap production, and endolysosomal signaling. Finally, we discuss the importance of understanding these molecular mechanisms in order to design novel approaches to modulate neutrophil-mediated inflammatory processes in a targeted fashion.
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Affiliation(s)
- Mahalakshmi Ramadass
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Sergio D Catz
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA
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47
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Davis S, Wang J, Ferro-Novick S. Crosstalk between the Secretory and Autophagy Pathways Regulates Autophagosome Formation. Dev Cell 2017; 41:23-32. [PMID: 28399396 DOI: 10.1016/j.devcel.2017.03.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 02/26/2017] [Accepted: 03/16/2017] [Indexed: 12/26/2022]
Abstract
The induction of autophagy by nutrient deprivation leads to a rapid increase in the formation of autophagosomes, unique organelles that replenish the cellular pool of nutrients by sequestering cytoplasmic material for degradation. The urgent need for membranes to form autophagosomes during starvation to maintain homeostasis leads to a dramatic rearrangement of intracellular membranes. Here we discuss recent findings that have begun to uncover how different parts of the secretory pathway directly and indirectly contribute to autophagosome formation during starvation.
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Affiliation(s)
- Saralin Davis
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0668, USA
| | - Juan Wang
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0668, USA
| | - Susan Ferro-Novick
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093-0668, USA.
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48
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RNF41 interacts with the VPS52 subunit of the GARP and EARP complexes. PLoS One 2017; 12:e0178132. [PMID: 28542518 PMCID: PMC5439944 DOI: 10.1371/journal.pone.0178132] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 04/12/2017] [Indexed: 11/19/2022] Open
Abstract
RNF41 (Ring Finger Protein 41) is an E3 ubiquitin ligase involved in the intracellular sorting and function of a diverse set of substrates. Next to BRUCE and Parkin, RNF41 can directly ubiquitinate ErbB3, IL-3, EPO and RARα receptors or downstream signaling molecules such as Myd88, TBK1 and USP8. In this way it can regulate receptor signaling and routing. To further elucidate the molecular mechanism behind the role of RNF41 in intracellular transport we performed an Array MAPPIT (Mammalian Protein-Protein Interaction Trap) screen using an extensive set of proteins derived from the human ORFeome collection. This paper describes the identification of VPS52, a subunit of the GARP (Golgi-Associated Retrograde Protein) and the EARP (Endosome-Associated Recycling Protein) complexes, as a novel interaction partner of RNF41. Through interaction via their coiled coil domains, RNF41 ubiquitinates and relocates VPS52 away from VPS53, a common subunit of the GARP and EARP complexes, towards RNF41 bodies.
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Harris MC, Cislo D, Lenz JS, Umbach C, Lindau M. AFM/TIRF force clamp measurements of neurosecretory vesicle tethers reveal characteristic unfolding steps. PLoS One 2017; 12:e0173993. [PMID: 28323853 PMCID: PMC5360256 DOI: 10.1371/journal.pone.0173993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 03/01/2017] [Indexed: 12/31/2022] Open
Abstract
Although several proteins have been implicated in secretory vesicle tethering, the identity and mechanical properties of the components forming the physical vesicle-plasma membrane link remain unknown. Here we present the first experimental measurements of nanomechanical properties of secretory vesicle-plasma membrane tethers using combined AFM force clamp and TIRF microscopy on membrane sheets from PC12 cells expressing the vesicle marker ANF-eGFP. Application of pulling forces generated tether extensions composed of multiple steps with variable length. The frequency of short (<10 nm) tether extension events was markedly higher when a fluorescent vesicle was present at the cantilever tip and increased in the presence of GTPγS, indicating that these events reflect specifically the properties of vesicle-plasma membrane tethers. The magnitude of the short tether extension events is consistent with extension lengths expected from progressive unfolding of individual helices of the exocyst complex, supporting its direct role in forming the physical vesicle-plasma membrane link.
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Affiliation(s)
- Mark C. Harris
- School of Applied and Engineering Physics, Engineering, Cornell University, Ithaca, NY, United States of America
| | - Dillon Cislo
- School of Applied and Engineering Physics, Engineering, Cornell University, Ithaca, NY, United States of America
| | - Joan S. Lenz
- School of Applied and Engineering Physics, Engineering, Cornell University, Ithaca, NY, United States of America
| | - Christopher Umbach
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, United States of America
| | - Manfred Lindau
- School of Applied and Engineering Physics, Engineering, Cornell University, Ithaca, NY, United States of America
- Laboratory for Nanoscale Cell Biology, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany
- * E-mail:
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Saimani U, Kim K. Traffic from the endosome towards trans-Golgi network. Eur J Cell Biol 2017; 96:198-205. [PMID: 28256269 DOI: 10.1016/j.ejcb.2017.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 01/24/2017] [Accepted: 02/16/2017] [Indexed: 11/16/2022] Open
Abstract
Retrograde passage of a transport carrier entails cargo sorting at the endosome, generation of a cargo-laden carrier and its movement along cytoskeletal tracks towards trans-Golgi network (TGN), tethering at the TGN, and fusion with the Golgi membrane. Significant advances have been made in understanding this traffic system, revealing molecular requirements in each step and the functional connection between them as well as biomedical implication of the dysregulation of those important traffic factors. This review focuses on describing up-to-date action mechanisms for retrograde transport from the endosomal system to the TGN.
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Affiliation(s)
- Uma Saimani
- Department of Biology, Missouri State University, 901 S National, Springfield, MO 65807, United States
| | - Kyoungtae Kim
- Department of Biology, Missouri State University, 901 S National, Springfield, MO 65807, United States.
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