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Xing Y, Huang L, Jian Y, Zhang Z, Zhao X, Zhang X, Fu T, Zhang Y, Wang Y, Zhang X. GORASP2 promotes phagophore closure and autophagosome maturation into autolysosomes. Autophagy 2024:1-17. [PMID: 39056394 DOI: 10.1080/15548627.2024.2375785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 06/25/2024] [Accepted: 06/29/2024] [Indexed: 07/28/2024] Open
Abstract
As the central hub of the secretory pathway, the Golgi apparatus plays a crucial role in maintaining cellular homeostasis in response to stresses. Recent studies have revealed the involvement of the Golgi tether, GORASP2, in facilitating autophagosome-lysosome fusion by connecting LC3-II and LAMP2 during nutrient starvation. However, the precise mechanism remains elusive. In this study, utilizing super-resolution microscopy, we observed GORASP2 localization on the surface of autophagosomes during glucose starvation. Depletion of GORASP2 hindered phagophore closure by regulating the association between VPS4A and the ESCRT-III component, CHMP2A. Furthermore, we found that GORASP2 controls RAB7A activity by modulating its GEF complex, MON1A-CCZ1, thereby impacting RAB7A's interaction with the HOPS complex. The assembly of both STX17-SNAP29-VAMP8 and YKT6-SNAP29-STX7 SNARE complexes was also attenuated without GORASP2. These findings suggest that GORASP2 helps seal autophagosomes and activate the RAB7A-HOPS-SNAREs membrane fusion machinery for autophagosome maturation, highlighting its membrane tethering function in response to stresses.Abbreviations: BafA1: bafilomycin A1; ESCRT: endosomal sorting complex required for transport; FPP: fluorescence protease protection; GEF: guanine nucleotide exchange factor; GFP: green fluorescent protein; GORASP2: golgi reassembly stacking protein 2; GSB: glucose starvation along with bafilomycin A1; HOPS: homotypic fusion and protein sorting; LAMP2: lysosomal associated membrane protein 2; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; PBS: phosphate-buffered saline; PtdIns3K: phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; PK: proteinase K; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SIM: structured illumination microscopy; UVRAG: UV radiation resistance associated.
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Affiliation(s)
- Yusheng Xing
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Lei Huang
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yannan Jian
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Zhenqian Zhang
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Xiaodan Zhao
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Xing Zhang
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Tingting Fu
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yue Zhang
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yijie Wang
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Xiaoyan Zhang
- College of Biomedicine and Health, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
- Hubei Hongshan Laboratory, Wuhan, Hubei, China
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2
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Shvarev D, König C, Susan N, Langemeyer L, Walter S, Perz A, Fröhlich F, Ungermann C, Moeller A. Structure of the endosomal CORVET tethering complex. Nat Commun 2024; 15:5227. [PMID: 38898033 PMCID: PMC11187117 DOI: 10.1038/s41467-024-49137-9] [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] [Received: 11/09/2023] [Accepted: 05/24/2024] [Indexed: 06/21/2024] Open
Abstract
Cells depend on their endolysosomal system for nutrient uptake and downregulation of plasma membrane proteins. These processes rely on endosomal maturation, which requires multiple membrane fusion steps. Early endosome fusion is promoted by the Rab5 GTPase and its effector, the hexameric CORVET tethering complex, which is homologous to the lysosomal HOPS. How these related complexes recognize their specific target membranes remains entirely elusive. Here, we solve the structure of CORVET by cryo-electron microscopy and revealed its minimal requirements for membrane tethering. As expected, the core of CORVET and HOPS resembles each other. However, the function-defining subunits show marked structural differences. Notably, we discover that unlike HOPS, CORVET depends not only on Rab5 but also on phosphatidylinositol-3-phosphate (PI3P) and membrane lipid packing defects for tethering, implying that an organelle-specific membrane code enables fusion. Our data suggest that both shape and membrane interactions of CORVET and HOPS are conserved in metazoans, thus providing a paradigm how tethering complexes function.
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Affiliation(s)
- Dmitry Shvarev
- Department of Biology/Chemistry, Structural Biology Section, Osnabrück University, 49076, Osnabrück, Germany
| | - Caroline König
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, 49076, Osnabrück, Germany
| | - Nicole Susan
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, 49076, Osnabrück, Germany
| | - Lars Langemeyer
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, 49076, Osnabrück, Germany
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), Osnabrück University, 49076, Osnabrück, Germany
| | - Stefan Walter
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), Osnabrück University, 49076, Osnabrück, Germany
| | - Angela Perz
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, 49076, Osnabrück, Germany
| | - Florian Fröhlich
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), Osnabrück University, 49076, Osnabrück, Germany
- Department of Biology/Chemistry, Bioanalytical Chemistry Section, Osnabrück University, 49076, Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, 49076, Osnabrück, Germany.
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), Osnabrück University, 49076, Osnabrück, Germany.
| | - Arne Moeller
- Department of Biology/Chemistry, Structural Biology Section, Osnabrück University, 49076, Osnabrück, Germany.
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), Osnabrück University, 49076, Osnabrück, Germany.
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Klössel S, Zhu Y, Amado L, Bisinski DD, Ruta J, Liu F, González Montoro A. Yeast TLDc domain proteins regulate assembly state and subcellular localization of the V-ATPase. EMBO J 2024; 43:1870-1897. [PMID: 38589611 PMCID: PMC11066047 DOI: 10.1038/s44318-024-00097-2] [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] [Received: 01/18/2024] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 04/10/2024] Open
Abstract
Yeast vacuoles perform crucial cellular functions as acidic degradative organelles, storage compartments, and signaling hubs. These functions are mediated by important protein complexes, including the vacuolar-type H+-ATPase (V-ATPase), responsible for organelle acidification. To gain a more detailed understanding of vacuole function, we performed cross-linking mass spectrometry on isolated vacuoles, detecting many known as well as novel protein-protein interactions. Among these, we identified the uncharacterized TLDc-domain-containing protein Rtc5 as a novel interactor of the V-ATPase. We further analyzed the influence of Rtc5 and of Oxr1, the only other yeast TLDc-domain-containing protein, on V-ATPase function. We find that both Rtc5 and Oxr1 promote the disassembly of the vacuolar V-ATPase in vivo, counteracting the role of the RAVE complex, a V-ATPase assembly chaperone. Furthermore, Oxr1 is necessary for the retention of a Golgi-specific subunit of the V-ATPase in this compartment. Collectively, our results shed light on the in vivo roles of yeast TLDc-domain proteins as regulators of the V-ATPase, highlighting the multifaceted regulation of this crucial protein complex.
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Affiliation(s)
- Samira Klössel
- Osnabrück University, Department of Biology/Chemistry, Cellular Communication Laboratory, Barbarastrasse 13, 49076, Osnabrück, Germany
| | - Ying Zhu
- Department of Structural Biology, Leibniz - Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Str. 10, Berlin, 13125, Germany
| | - Lucia Amado
- Osnabrück University, Department of Biology/Chemistry, Cellular Communication Laboratory, Barbarastrasse 13, 49076, Osnabrück, Germany
| | - Daniel D Bisinski
- Osnabrück University, Department of Biology/Chemistry, Cellular Communication Laboratory, Barbarastrasse 13, 49076, Osnabrück, Germany
| | - Julia Ruta
- Department of Structural Biology, Leibniz - Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Str. 10, Berlin, 13125, Germany
| | - Fan Liu
- Department of Structural Biology, Leibniz - Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Roessle-Str. 10, Berlin, 13125, Germany
- Charité - Universitätsmedizin Berlin, Charitépl. 1, 10117, Berlin, Germany
| | - Ayelén González Montoro
- Osnabrück University, Department of Biology/Chemistry, Cellular Communication Laboratory, Barbarastrasse 13, 49076, Osnabrück, Germany.
- Osnabrück University, Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Barbarastrasse 11, 49076, Osnabrück, Germany.
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Zhu Y, Liu F, Jian F, Rong Y. Recent progresses in the late stages of autophagy. CELL INSIGHT 2024; 3:100152. [PMID: 38435435 PMCID: PMC10904915 DOI: 10.1016/j.cellin.2024.100152] [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: 10/18/2023] [Revised: 01/30/2024] [Accepted: 01/30/2024] [Indexed: 03/05/2024]
Abstract
Autophagy, a lysosome-dependent degradation process, plays a crucial role in maintaining cell homeostasis. It serves as a vital mechanism for adapting to stress and ensuring intracellular quality control. Autophagy deficiencies or defects are linked to numerous human disorders, especially those associated with neuronal degeneration or metabolic diseases. Yoshinori Ohsumi was honored with the Nobel Prize in Physiology or Medicine in 2016 for his groundbreaking discoveries regarding autophagy mechanisms. Over the past few decades, autophagy research has predominantly concentrated on the early stages of autophagy, with relatively limited attention given to the late stages. Nevertheless, recent studies have witnessed substantial advancements in understanding the molecular intricacies of the late stages, which follows autophagosome formation. This review provides a comprehensive summary of the recent progresses in comprehending the molecular mechanisms of the late stages of autophagy.
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Affiliation(s)
- YanYan Zhu
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, China
- Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Fengping Liu
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, China
- Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Fenglei Jian
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, China
- Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Yueguang Rong
- School of Basic Medicine, Tongji Medical College and State Key Laboratory for Diagnosis and Treatment of Severe Zoonostic Infectious Disease, Huazhong University of Science and Technology, Wuhan, China
- Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, Hubei, China
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5
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Chen JW, Liew FF, Tan HW, Misran M, Chung I. Cholesterol-linoleic acid liposomes induced extracellular vesicles secretion from immortalized adipose-derived mesenchymal stem cells for in vitro cell migration. ARTIFICIAL CELLS, NANOMEDICINE, AND BIOTECHNOLOGY 2023; 51:346-360. [PMID: 37524112 DOI: 10.1080/21691401.2023.2237534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 06/28/2023] [Accepted: 07/12/2023] [Indexed: 08/02/2023]
Abstract
Extracellular vesicles (EVs) are small vesicles that are naturally released by cells and play a crucial role in cell-to-cell communication, tissue repair and regeneration. As naturally secreted EVs are limited, liposomes with different physicochemical properties, such as 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) and linoleic acid (LA) with modifications have been formulated to improve EVs secretion for in vitro wound healing. Various analyses, including dynamic light scattering (DLS) and transmission electron microscopy (TEM) were performed to monitor the successful preparation of different types of liposomes. The results showed that cholesterol-LA liposomes significantly improved the secretion of EVs from immortalized adipose-derived mesenchymal stem cells (AD-MSCs) by 1.5-fold. Based on the cell migration effects obtained from scratch assay, both LA liposomal-induced EVs and cholesterol-LA liposomal-induced EVs significantly enhanced the migration of human keratinocytes (HaCaT) cell line. These findings suggested that LA and cholesterol-LA liposomes that enhance EVs secretion are potentially useful and can be extended for various tissue regeneration applications.
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Affiliation(s)
- Jzit Weii Chen
- Department of Pharmacology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Fong Fong Liew
- Department of Oral Biology and Biomedical Science, Faculty of Dentistry, MAHSA University, Selangor, Malaysia
| | - Hsiao Wei Tan
- Institute of Research Management and Services, Research and Innovation Management Complex, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Misni Misran
- Department of Chemistry, Faculty of Science, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Ivy Chung
- Department of Pharmacology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
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6
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Terawaki S, Vasilev F, Moriwaki T, Otomo T. HOPS, CORVET and newly-identified Hybrid tethering complexes contribute differentially towards multiple modes of endocytosis. Sci Rep 2023; 13:18734. [PMID: 37907479 PMCID: PMC10618185 DOI: 10.1038/s41598-023-45418-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/19/2023] [Indexed: 11/02/2023] Open
Abstract
Vesicular transport driven by membrane trafficking systems conserved in eukaryotes is critical to cellular functionality and homeostasis. It is known that homotypic fusion and vacuole protein sorting (HOPS) and class C core endosomal vacuole tethering (CORVET) interact with Rab-GTPases and SNARE proteins to regulate vesicle transport, fusion, and maturation in autophagy and endocytosis pathways. In this study, we identified two novel "Hybrid" tethering complexes in mammalian cells in which one of the subunits of HOPS or CORVET is replaced with the subunit from the other. Substrates taken up by receptor-mediated endocytosis or pinocytosis were transported by distinctive pathways, and the newly identified hybrid complexes contributed to pinocytosis in the presence of HOPS, whereas receptor-mediated endocytosis was exclusively dependent on HOPS. Our study provides new insights into the molecular mechanisms of the endocytic pathway and the function of the vacuolar protein sorting-associated (VPS) protein family.
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Affiliation(s)
- Seigo Terawaki
- Department of Molecular and Genetic Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan
| | - Filipp Vasilev
- Department of Molecular and Genetic Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan
| | - Takahito Moriwaki
- Department of Molecular and Genetic Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan
| | - Takanobu Otomo
- Department of Molecular and Genetic Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan.
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7
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Zhang S, Tong M, Zheng D, Huang H, Li L, Ungermann C, Pan Y, Luo H, Lei M, Tang Z, Fu W, Chen S, Liu X, Zhong Q. C9orf72-catalyzed GTP loading of Rab39A enables HOPS-mediated membrane tethering and fusion in mammalian autophagy. Nat Commun 2023; 14:6360. [PMID: 37821429 PMCID: PMC10567733 DOI: 10.1038/s41467-023-42003-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 09/25/2023] [Indexed: 10/13/2023] Open
Abstract
The multi-subunit homotypic fusion and vacuole protein sorting (HOPS) membrane-tethering complex is required for autophagosome-lysosome fusion in mammals, yet reconstituting the mammalian HOPS complex remains a challenge. Here we propose a "hook-up" model for mammalian HOPS complex assembly, which requires two HOPS sub-complexes docking on membranes via membrane-associated Rabs. We identify Rab39A as a key small GTPase that recruits HOPS onto autophagic vesicles. Proper pairing with Rab2 and Rab39A enables HOPS complex assembly between proteoliposomes for its tethering function, facilitating efficient membrane fusion. GTP loading of Rab39A is important for the recruitment of HOPS to autophagic membranes. Activation of Rab39A is catalyzed by C9orf72, a guanine exchange factor associated with amyotrophic lateral sclerosis and familial frontotemporal dementia. Constitutive activation of Rab39A can rescue autophagy defects caused by C9orf72 depletion. These results therefore reveal a crucial role for the C9orf72-Rab39A-HOPS axis in autophagosome-lysosome fusion.
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Affiliation(s)
- Shen Zhang
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Mindan Tong
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Denghao Zheng
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Huiying Huang
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Linsen Li
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Christian Ungermann
- Osnabrück University, Department of Biology/Chemistry, Biochemistry section, Osnabrück, Germany
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
| | - Yi Pan
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hanyan Luo
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Ming Lei
- State Key Laboratory of Oncogenes and Related Genes, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 200011, Shanghai, China
- Shanghai Institute of Precision Medicine, 200125, Shanghai, China
| | - Zaiming Tang
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wan Fu
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - She Chen
- National Institute of Biological Sciences, 102206, Beijing, China
| | - Xiaoxia Liu
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Qing Zhong
- Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Wang T, Yan L, Wang L, Sun J, Qu H, Ma Y, Song R, Tong X, Zhu J, Yuan Y, Gu J, Bian J, Liu Z, Zou H. VPS41-mediated incomplete autophagy aggravates cadmium-induced apoptosis in mouse hepatocytes. JOURNAL OF HAZARDOUS MATERIALS 2023; 459:132243. [PMID: 37562348 DOI: 10.1016/j.jhazmat.2023.132243] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 08/04/2023] [Accepted: 08/05/2023] [Indexed: 08/12/2023]
Abstract
Exposure to cadmium (Cd), an environmental heavy metal contaminant, is a serious threat to global health that increases the burden of liver diseases. Autophagy and apoptosis are important in Cd-induced liver injury. However, the regulatory mechanisms involved in the progression of Cd-induced liver damage are poorly understood. Herein, we investigated the role of vacuolar protein sorting 41 (VPS41) in Cd-induced autophagy and apoptosis in hepatocytes. We used targeted VPS41 regulation to elucidate the mechanism of Cd-induced hepatotoxicity. Our data showed that Cd triggered incomplete autophagy by downregulating VPS41, aggravating Cd-induced hepatocyte apoptosis. Mechanistically, Cd-induced VPS41 downregulation interfered with the mTORC1-TFEB/TFE3 axis, leading to an imbalance in autophagy initiation and termination and abnormal activation of autophagy. Moreover, Cd-induced downregulation of VPS41 inhibited autophagosome-lysosome fusion, leading to blocked autophagic flux. This triggers incomplete autophagy, which causes excessive P62 accumulation, accelerating Caspase-9 (CASP9) cleavage. Incomplete autophagy blocks clearance of cleaved CASP9 (CL-CASP9) via the autophagic pathway, promoting apoptosis. Notably, VPS41 overexpression alleviated Cd-induced incomplete autophagy and apoptosis, independent of the homotypic fusion and protein sorting complex. This study provides a new mechanistic understanding of the relationship between autophagy and apoptosis, suggesting that VPS41 is a new therapeutic target for Cd-induced liver damage.
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Affiliation(s)
- Tao Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Lianqi Yan
- Department of Orthopedics, The Second Xiangya Hospital of Central South University, Changsha 410000, Hunan, China; Department of Orthopedics, Clinical Medical College of Yangzhou University, Subei People's Hospital, Yangzhou 225009, Jiangsu, China
| | - Li Wang
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Jian Sun
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Huayi Qu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Yonggang Ma
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Ruilong Song
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Xishuai Tong
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou 225009, Jiangsu, China
| | - Jiaqiao Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Yan Yuan
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Jianhong Gu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Jianchun Bian
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Zongping Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China
| | - Hui Zou
- College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, Jiangsu, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, Jiangsu, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou 225009, Jiangsu, China.
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9
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Rodriguez-Furlan C, Borna R, Betz O. RAB7 GTPases as coordinators of plant endomembrane traffic. FRONTIERS IN PLANT SCIENCE 2023; 14:1240973. [PMID: 37662169 PMCID: PMC10470000 DOI: 10.3389/fpls.2023.1240973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 08/01/2023] [Indexed: 09/05/2023]
Abstract
The ras gene from rat brain (RAB) family of small GTPases is highly conserved among eukaryotes and regulates endomembrane trafficking pathways. RAB7, in particular, has been linked to various processes involved in regulating endocytic and autophagic pathways. Plants have several copies of RAB7 proteins that reflect the intricacy of their endomembrane transport systems. RAB7 activity regulates different pathways of endomembrane trafficking in plants: (1) endocytic traffic to the vacuole; (2) biosynthetic traffic to the vacuole; and (3) recycling from the late endosome to the secretory pathway. During certain developmental and stress related processes another pathway becomes activated (4) autophagic trafficking towards the vacuole that is also regulated by RAB7. RAB7s carry out these functions by interacting with various effector proteins. Current research reveals many unexplored RAB7 functions in connection with stress responses. Thus, this review describes a comprehensive summary of current knowledge of plant RAB7's functions, discusses unresolved challenges, and recommends prospective future research directions.
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10
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Del Vecchio M, Amado L, Cogan AP, Meert E, Rosseels J, Franssens V, Govers SK, Winderickx J, Montoro AG. Multiple tethers of organelle contact sites are involved in α-synuclein toxicity in yeast. Mol Biol Cell 2023; 34:ar84. [PMID: 37074954 PMCID: PMC10398879 DOI: 10.1091/mbc.e23-01-0029] [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: 01/31/2023] [Revised: 04/05/2023] [Accepted: 04/12/2023] [Indexed: 04/20/2023] Open
Abstract
The protein α-synuclein (α-syn) is one of the major factors linked to Parkinson's disease, yet how its misfolding and deposition contribute to the pathology remains largely elusive. Recently, contact sites among organelles were implicated in the development of this disease. Here, we used the budding yeast Saccharomyces cerevisiae, in which organelle contact sites have been characterized extensively, as a model to investigate their role in α-syn cytotoxicity. We observed that lack of specific tethers that anchor the endoplasmic reticulum to the plasma membrane resulted in cells with increased resistance to α-syn expression. Additionally, we found that strains lacking two dual-function proteins involved in contact sites, Mdm10 and Vps39, were resistant to the expression of α-syn. In the case of Mdm10, we found that this is related to its function in mitochondrial protein biogenesis and not to its role as a contact site tether. In contrast, both functions of Vps39, in vesicular transport and as a tether of the vacuole-mitochondria contact site, were required to support α-syn toxicity. Overall, our findings support that interorganelle communication through membrane contact sites is highly relevant for α-syn-mediated toxicity.
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Affiliation(s)
- Mara Del Vecchio
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
- Department of Biology, Microbial Systems Cell Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Lucia Amado
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
| | - Alexandra P. Cogan
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
| | - Els Meert
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Joelle Rosseels
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Vanessa Franssens
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Sander K. Govers
- Department of Biology, Microbial Systems Cell Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Ayelén González Montoro
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics Osnabrück, 49076 Osnabrück, Germany
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11
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Shelke GV, Williamson CD, Jarnik M, Bonifacino JS. Inhibition of endolysosome fusion increases exosome secretion. J Cell Biol 2023; 222:e202209084. [PMID: 37213076 PMCID: PMC10202829 DOI: 10.1083/jcb.202209084] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 02/04/2023] [Accepted: 03/17/2023] [Indexed: 05/23/2023] Open
Abstract
Exosomes are small vesicles that are secreted from cells to dispose of undegraded materials and mediate intercellular communication. A major source of exosomes is intraluminal vesicles within multivesicular endosomes that undergo exocytic fusion with the plasma membrane. An alternative fate of multivesicular endosomes is fusion with lysosomes, resulting in degradation of the intraluminal vesicles. The factors that determine whether multivesicular endosomes fuse with the plasma membrane or with lysosomes are unknown. In this study, we show that impairment of endolysosomal fusion by disruption of a pathway involving the BLOC-one-related complex (BORC), the small GTPase ARL8, and the tethering factor HOPS increases exosome secretion by preventing the delivery of intraluminal vesicles to lysosomes. These findings demonstrate that endolysosomal fusion is a critical determinant of the amount of exosome secretion and suggest that suppression of the BORC-ARL8-HOPS pathway could be used to boost exosome yields in biotechnology applications.
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Affiliation(s)
- Ganesh Vilas Shelke
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Chad D. Williamson
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Michal Jarnik
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Juan S. Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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12
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Li H, Gong W, Sun W, Yao Y, Han Y. Role of VPS39, a key tethering protein for endolysosomal trafficking and mitochondria-lysosome crosstalk, in health and disease. J Cell Biochem 2023. [PMID: 36924104 DOI: 10.1002/jcb.30396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/12/2023] [Accepted: 02/28/2023] [Indexed: 03/18/2023]
Abstract
The coordinated interaction between mitochondria and lysosomes, mainly manifested by mitophagy, mitochondria-derived vesicles, and direct physical contact, is essential for maintaining cellular life activities. The VPS39 subunit of the homotypic fusion and protein sorting complex could play a key role in the regulation of organelle dynamics, such as endolysosomal trafficking and mitochondria-vacuole/lysosome crosstalk, thus contributing to a variety of physiological functions. The abnormalities of VPS39 and related subunits have been reported to be involved in the pathological process of some diseases. Here, we analyze the potential mechanisms and the existing problems of VPS39 in regulating organelle dynamics, which, in turn, regulate physiological functions and disease pathogenesis, so as to provide new clues for facilitating the discovery of therapeutic targets for mitochondrial and lysosomal diseases.
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Affiliation(s)
- Hanbing Li
- Institute of Pharmacology, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, China
| | - Wenwen Gong
- Institute of Pharmacology, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, China
| | - Weiyun Sun
- Institute of Pharmacology, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, China
| | - Yuanfa Yao
- Institute of Pharmacology, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, China
| | - Yubing Han
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou, China.,Britton Chance Center for Biomedical Photonics-MoE Key Laboratory for Biomedical Photonics, Advanced Biomedical Imaging Facility-Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, China
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13
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Kümmel D, Herrmann E, Langemeyer L, Ungermann C. Molecular insights into endolysosomal microcompartment formation and maintenance. Biol Chem 2022; 404:441-454. [PMID: 36503831 DOI: 10.1515/hsz-2022-0294] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 11/22/2022] [Indexed: 12/14/2022]
Abstract
Abstract
The endolysosomal system of eukaryotic cells has a key role in the homeostasis of the plasma membrane, in signaling and nutrient uptake, and is abused by viruses and pathogens for entry. Endocytosis of plasma membrane proteins results in vesicles, which fuse with the early endosome. If destined for lysosomal degradation, these proteins are packaged into intraluminal vesicles, converting an early endosome to a late endosome, which finally fuses with the lysosome. Each of these organelles has a unique membrane surface composition, which can form segmented membrane microcompartments by membrane contact sites or fission proteins. Furthermore, these organelles are in continuous exchange due to fission and fusion events. The underlying machinery, which maintains organelle identity along the pathway, is regulated by signaling processes. Here, we will focus on the Rab5 and Rab7 GTPases of early and late endosomes. As molecular switches, Rabs depend on activating guanine nucleotide exchange factors (GEFs). Over the last years, we characterized the Rab7 GEF, the Mon1-Ccz1 (MC1) complex, and key Rab7 effectors, the HOPS complex and retromer. Structural and functional analyses of these complexes lead to a molecular understanding of their function in the context of organelle biogenesis.
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Affiliation(s)
- Daniel Kümmel
- Institute of Biochemistry, University of Münster , Corrensstraße 36 , D-48149 Münster , Germany
| | - Eric Herrmann
- Institute of Biochemistry, University of Münster , Corrensstraße 36 , D-48149 Münster , Germany
| | - Lars Langemeyer
- Department of Biology/Chemistry, Biochemistry section , Osnabrück University , Barbarastraße 13 , D-49076 Osnabrück , Germany
- Center of Cellular Nanoanalytics (CellNanOs) , Osnabrück University , Barbarastraße 11 , D-49076 Osnabrück , Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry section , Osnabrück University , Barbarastraße 13 , D-49076 Osnabrück , Germany
- Center of Cellular Nanoanalytics (CellNanOs) , Osnabrück University , Barbarastraße 11 , D-49076 Osnabrück , Germany
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14
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Lu G, Wang Y, Shi Y, Zhang Z, Huang C, He W, Wang C, Shen HM. Autophagy in health and disease: From molecular mechanisms to therapeutic target. MedComm (Beijing) 2022; 3:e150. [PMID: 35845350 PMCID: PMC9271889 DOI: 10.1002/mco2.150] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/01/2022] [Accepted: 06/02/2022] [Indexed: 02/05/2023] Open
Abstract
Macroautophagy/autophagy is an evolutionally conserved catabolic process in which cytosolic contents, such as aggregated proteins, dysfunctional organelle, or invading pathogens, are sequestered by the double‐membrane structure termed autophagosome and delivered to lysosome for degradation. Over the past two decades, autophagy has been extensively studied, from the molecular mechanisms, biological functions, implications in various human diseases, to development of autophagy‐related therapeutics. This review will focus on the latest development of autophagy research, covering molecular mechanisms in control of autophagosome biogenesis and autophagosome–lysosome fusion, and the upstream regulatory pathways including the AMPK and MTORC1 pathways. We will also provide a systematic discussion on the implication of autophagy in various human diseases, including cancer, neurodegenerative disorders (Alzheimer disease, Parkinson disease, Huntington's disease, and Amyotrophic lateral sclerosis), metabolic diseases (obesity and diabetes), viral infection especially SARS‐Cov‐2 and COVID‐19, cardiovascular diseases (cardiac ischemia/reperfusion and cardiomyopathy), and aging. Finally, we will also summarize the development of pharmacological agents that have therapeutic potential for clinical applications via targeting the autophagy pathway. It is believed that decades of hard work on autophagy research is eventually to bring real and tangible benefits for improvement of human health and control of human diseases.
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Affiliation(s)
- Guang Lu
- Department of Physiology, Zhongshan School of Medicine Sun Yat-sen University Guangzhou China
| | - Yu Wang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine Sichuan University and Collaborative Innovation Center for Biotherapy Chengdu China
| | - Yin Shi
- Department of Biochemistry Zhejiang University School of Medicine Hangzhou China
| | - Zhe Zhang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine Sichuan University and Collaborative Innovation Center for Biotherapy Chengdu China
| | - Canhua Huang
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, and West China School of Basic Medical Sciences & Forensic Medicine Sichuan University and Collaborative Innovation Center for Biotherapy Chengdu China
| | - Weifeng He
- State Key Laboratory of Trauma, Burn and Combined Injury, Institute of Burn Research Southwest Hospital Army Medical University Chongqing China
| | - Chuang Wang
- Department of Pharmacology, Provincial Key Laboratory of Pathophysiology Ningbo University School of Medicine Ningbo Zhejiang China
| | - Han-Ming Shen
- Department of Biomedical Sciences, Faculty of Health Sciences, Ministry of Education Frontiers Science Center for Precision Oncology University of Macau Macau China
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15
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Bisinski DD, Gomes Castro I, Mari M, Walter S, Fröhlich F, Schuldiner M, González Montoro A. Cvm1 is a component of multiple vacuolar contact sites required for sphingolipid homeostasis. J Biophys Biochem Cytol 2022; 221:213309. [PMID: 35766971 PMCID: PMC9247719 DOI: 10.1083/jcb.202103048] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/05/2022] [Accepted: 06/13/2022] [Indexed: 02/03/2023] Open
Abstract
Membrane contact sites are specialized platforms formed between most organelles that enable them to exchange metabolites and influence the dynamics of each other. The yeast vacuole is a degradative organelle equivalent to the lysosome in higher eukaryotes with important roles in ion homeostasis and metabolism. Using a high-content microscopy screen, we identified Ymr160w (Cvm1, for contact of the vacuole membrane 1) as a novel component of three different contact sites of the vacuole: with the nuclear endoplasmic reticulum, the mitochondria, and the peroxisomes. At the vacuole-mitochondria contact site, Cvm1 acts as a tether independently of previously known tethers. We show that changes in Cvm1 levels affect sphingolipid homeostasis, altering the levels of multiple sphingolipid classes and the response of sphingolipid-sensing signaling pathways. Furthermore, the contact sites formed by Cvm1 are induced upon a decrease in sphingolipid levels. Altogether, our work identifies a novel protein that forms multiple contact sites and supports a role of lysosomal contacts in sphingolipid homeostasis.
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Affiliation(s)
- Daniel D. Bisinski
- Department of Biology/Chemistry, Cellular Communication Laboratory, University of Osnabrück, Osnabrück, Germany
| | - Inês Gomes Castro
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Muriel Mari
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Stefan Walter
- Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany
| | - Florian Fröhlich
- Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany,Department of Biology/Chemistry, Molecular Membrane Biology Group, University of Osnabrück, Osnabrück, Germany
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ayelén González Montoro
- Department of Biology/Chemistry, Cellular Communication Laboratory, University of Osnabrück, Osnabrück, Germany,Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany
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16
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Gao J, Nicastro R, Péli-Gulli MP, Grziwa S, Chen Z, Kurre R, Piehler J, De Virgilio C, Fröhlich F, Ungermann C. The HOPS tethering complex is required to maintain signaling endosome identity and TORC1 activity. J Biophys Biochem Cytol 2022; 221:213121. [PMID: 35404387 PMCID: PMC9011323 DOI: 10.1083/jcb.202109084] [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: 09/17/2021] [Revised: 01/27/2022] [Accepted: 02/28/2022] [Indexed: 12/04/2022] Open
Abstract
The endomembrane system of eukaryotic cells is essential for cellular homeostasis during growth and proliferation. Previous work showed that a central regulator of growth, namely the target of rapamycin complex 1 (TORC1), binds both membranes of vacuoles and signaling endosomes (SEs) that are distinct from multivesicular bodies (MVBs). Interestingly, the endosomal TORC1, which binds membranes in part via the EGO complex, critically defines vacuole integrity. Here, we demonstrate that SEs form at a branch point of the biosynthetic and endocytic pathways toward the vacuole and depend on MVB biogenesis. Importantly, function of the HOPS tethering complex is essential to maintain the identity of SEs and proper endosomal and vacuolar TORC1 activities. In HOPS mutants, the EGO complex redistributed to the Golgi, which resulted in a partial mislocalization of TORC1. Our study uncovers that SE function requires a functional HOPS complex and MVBs, suggesting a tight link between trafficking and signaling along the endolysosomal pathway.
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Affiliation(s)
- Jieqiong Gao
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Raffaele Nicastro
- Department of Biology, University of Fribourg, Chemin du Musée, Fribourg, Switzerland
| | | | - Sophie Grziwa
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Zilei Chen
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
| | - Rainer Kurre
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
| | - Jacob Piehler
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
- Department of Biology/Chemistry, Biophysics Section, Osnabrück University, Osnabrück, Germany
| | - Claudio De Virgilio
- Department of Biology, University of Fribourg, Chemin du Musée, Fribourg, Switzerland
| | - Florian Fröhlich
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
- Department of Biology/Chemistry, Molecular Membrane Biology Section, Osnabrück University, Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, Osnabrück University, Osnabrück, Germany
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, Osnabrück, Germany
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17
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González Montoro A, Vargas Duarte P, Auffarth K, Walter S, Fröhlich F, Ungermann C. Subunit exchange among endolysosomal tethering complexes is linked to contact site formation at the vacuole. Mol Biol Cell 2021; 32:br14. [PMID: 34668759 PMCID: PMC8694092 DOI: 10.1091/mbc.e21-05-0227] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The hexameric HOPS (homotypic fusion and protein sorting) complex is a conserved tethering complex at the lysosome-like vacuole, where it mediates tethering and promotes all fusion events involving this organelle. The Vps39 subunit of this complex also engages in a membrane contact site between the vacuole and the mitochondria, called vCLAMP. Additionally, four subunits of HOPS are also part of the endosomal CORVET tethering complex. Here, we analyzed the partition of HOPS and CORVET subunits between the different complexes by tracing their localization and function. We find that Vps39 has a specific role in vCLAMP formation beyond tethering, and that vCLAMPs and HOPS compete for the same pool of Vps39. In agreement, we find that the CORVET subunit Vps3 can take the position of Vps39 in HOPS. This endogenous pool of a Vps3-hybrid complex is affected by Vps3 or Vps39 levels, suggesting that HOPS and CORVET assembly is dynamic. Our data shed light on how individual subunits of tethering complexes such as Vps39 can participate in other functions, while maintaining the remaining subcomplex available for its function in tethering and fusion.
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Affiliation(s)
- Ayelén González Montoro
- Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, 49076 Osnabrück, Germany
| | | | - Kathrin Auffarth
- Biochemistry section, Osnabrück University, 49076 Osnabrück, Germany
| | - Stefan Walter
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, 49076 Osnabrück, Germany
| | - Florian Fröhlich
- Molecular Membrane Biology section, Department of Biology/Chemistry, Osnabrück University, 49076 Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, 49076 Osnabrück, Germany
| | - Christian Ungermann
- Biochemistry section, Osnabrück University, 49076 Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), Osnabrück University, 49076 Osnabrück, Germany
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18
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Füllbrunn N, Li Z, Jorde L, Richter CP, Kurre R, Langemeyer L, Yu C, Meyer C, Enderlein J, Ungermann C, Piehler J, You C. Nanoscopic anatomy of dynamic multi-protein complexes at membranes resolved by graphene-induced energy transfer. eLife 2021; 10:62501. [PMID: 33513092 PMCID: PMC7847308 DOI: 10.7554/elife.62501] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 12/28/2020] [Indexed: 11/30/2022] Open
Abstract
Insights into the conformational organization and dynamics of proteins complexes at membranes is essential for our mechanistic understanding of numerous key biological processes. Here, we introduce graphene-induced energy transfer (GIET) to probe axial orientation of arrested macromolecules at lipid monolayers. Based on a calibrated distance-dependent efficiency within a dynamic range of 25 nm, we analyzed the conformational organization of proteins and complexes involved in tethering and fusion at the lysosome-like yeast vacuole. We observed that the membrane-anchored Rab7-like GTPase Ypt7 shows conformational reorganization upon interactions with effector proteins. Ensemble and time-resolved single-molecule GIET experiments revealed that the HOPS tethering complex, when recruited via Ypt7 to membranes, is dynamically alternating between a ‘closed’ and an ‘open’ conformation, with the latter possibly interacting with incoming vesicles. Our work highlights GIET as a unique spectroscopic ruler to reveal the axial orientation and dynamics of macromolecular complexes at biological membranes with sub-nanometer resolution. Proteins are part of the building blocks of life and are essential for structure, function and regulation of every cell, tissue and organ of the body. Proteins adopt different conformations to work efficiently within the various environments of a cell. They can also switch between shapes. One way to monitor how proteins change their shapes involves energy transfer. This approach can measure how close two proteins, or two parts of the same protein, are, by using dye labels that respond to each other when they are close together. For example, in a method called FRET, one dye label absorbs light and transfers the energy to the other label, which emits it as a different color of light. However, FRET only works over short distances (less than 10nm apart or 1/100,000th of a millimeter), so it is not useful for larger proteins. Here, Füllbrunn, Li et al. developed a method called GIET that uses graphene to analyze the dynamic structures of proteins on membrane surfaces. Graphene is a type of carbon nanomaterial that can absorb energy from dye labels and could provide a way to study protein interactions over longer distances. Graphene was deposited on a glass surface where it was coated with single layer of membrane, which could then be used to capture specific proteins. The results showed that GIET worked over longer distances (up to 30 nm) than FRET and could be used to study proteins attached to the membrane around graphene. Füllbrunn, Li et al. used it to examine a specific complex of proteins called HOPS, which is linked to multiple diseases, including Ebola, measuring distances between the head or tail of HOPS and the membrane to understand protein shapes. This revealed that HOPS adopts an upright position on membranes and alternates between open and closed shapes. The study of Füllbrunn, Li et al. highlights the ability of GIET to address unanswered questions about the function of protein complexes on membrane surfaces and sheds new light on the structural dynamics of HOPS in living cells. As it allows protein interactions to be studied over much greater distances, GIET could be a powerful new tool for cell biology research. Moreover, graphene is also useful in electron microscopy and both approaches combined could achieve a detailed structural picture of proteins in action.
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Affiliation(s)
- Nadia Füllbrunn
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Zehao Li
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany.,College of Life Sciences, Beijing University of Chemical Technology, Beijing, China
| | - Lara Jorde
- Department of Physics, University of Osnabrück, Osnabrück, Germany
| | - Christian P Richter
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Rainer Kurre
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Lars Langemeyer
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Changyuan Yu
- College of Life Sciences, Beijing University of Chemical Technology, Beijing, China
| | - Carola Meyer
- Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany.,Department of Physics, University of Osnabrück, Osnabrück, Germany
| | - Jörg Enderlein
- 3rd Institute of Physics - Biophysics, Georg August University, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Georg August University, Göttingen, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Jacob Piehler
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Changjiang You
- Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytics (CellNanOs), University of Osnabrück, Osnabrück, Germany
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19
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Schoppe J, Mari M, Yavavli E, Auffarth K, Cabrera M, Walter S, Fröhlich F, Ungermann C. AP-3 vesicle uncoating occurs after HOPS-dependent vacuole tethering. EMBO J 2020; 39:e105117. [PMID: 32840906 PMCID: PMC7560216 DOI: 10.15252/embj.2020105117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 07/16/2020] [Accepted: 07/22/2020] [Indexed: 11/09/2022] Open
Abstract
Heterotetrameric adapter (AP) complexes cooperate with the small GTPase Arf1 or lipids in cargo selection, vesicle formation, and budding at endomembranes in eukaryotic cells. While most AP complexes also require clathrin as the outer vesicle shell, formation of AP-3-coated vesicles involved in Golgi-to-vacuole transport in yeast has been postulated to depend on Vps41, a subunit of the vacuolar HOPS tethering complex. HOPS has also been identified as the tether of AP-3 vesicles on vacuoles. To unravel this conundrum of a dual Vps41 function, we anchored Vps41 stably to the mitochondrial outer membrane. By monitoring AP-3 recruitment, we now show that Vps41 can tether AP-3 vesicles to mitochondria, yet AP-3 vesicles can form in the absence of Vps41 or clathrin. By proximity labeling and mass spectrometry, we identify the Arf1 GTPase-activating protein (GAP) Age2 at the AP-3 coat and show that tethering, but not fusion at the vacuole can occur without complete uncoating. We conclude that AP-3 vesicles retain their coat after budding and that their complete uncoating occurs only after tethering at the vacuole.
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Affiliation(s)
- Jannis Schoppe
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Muriel Mari
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Erdal Yavavli
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Kathrin Auffarth
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Margarita Cabrera
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Farba, Barcelona, Spain
| | - Stefan Walter
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Florian Fröhlich
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany.,Department of Biology/Chemistry, Molecular Membrane Biology Section, University of Osnabrück, Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
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20
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Nie J. UNC0321 inhibits high glucose induced apoptosis in HUVEC by targeting Rab4. Biomed Pharmacother 2020; 131:110662. [PMID: 32877824 DOI: 10.1016/j.biopha.2020.110662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 08/07/2020] [Accepted: 08/20/2020] [Indexed: 01/03/2023] Open
Abstract
The vascular complications in heart, brain, kidney and retina are the most common chronic complications of diabetes mellitus (DM). At present, it has become a research hotspot to regulate the abnormal apoptosis of vascular endothelial cells for DM treatment. UNC0321 is a high affinity GPCRs inhibitor, and has potential practical value in chromatin remodeling. In this study, we treated HUVEC with UNC0321 in vitro, and found that UNC0321 inhibit the level of Cleaved-Caspase3 and Bax, thus inhibiting the apoptosis caused by high glucose. In addition, UNC0321 also promoted cell proliferation and migration by activating Akt / mTOR pathway. The transcriptome changes of HUVEC cells cultured with high glucose with or without the treatment of UNC0321 were analysis using sequencing. It was found that Rab4 expression was significantly inhibited after UNC0321 treatment. Subsequently, we overexpressed Rab4 in HUVEC cells cultured with high glucose, and found that overexpression of Rab4 promoted the apoptosis, and inhibited cell proliferation and migration. At the same time, after overexpression of Rab4 in HUVEC cells treated with UNC0321, the number of apoptosis was significantly increased, cell proliferation and migration were inhibited, and the activity of Akt / mTOR pathway decreased. These data suggested that overexpression of Rab4 effectively blocked the inhibition of apoptosis and the increase of cell proliferation induced by UNC0321. In conclusion, we found that UNC0321 inhibits the apoptosis of HUVEC cells caused by high glucose through inhibiting Rab4 expression, providing new potential drugs and targets for the treatment of diabetic vascular complications.
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Affiliation(s)
- Jieming Nie
- Department of Internal Medicine, The Third Affiliated Hospital of Guangzhou Medical University, PR China.
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21
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Manandhar SP, Siddiqah IM, Cocca SM, Gharakhanian E. A kinase cascade on the yeast lysosomal vacuole regulates its membrane dynamics: conserved kinase Env7 is phosphorylated by casein kinase Yck3. J Biol Chem 2020; 295:12262-12278. [PMID: 32647006 PMCID: PMC7443493 DOI: 10.1074/jbc.ra119.012346] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 06/02/2020] [Indexed: 01/15/2023] Open
Abstract
Membrane fusion/fission is a highly dynamic and conserved process that responds to intra- and extracellular signals. Whereas the molecular machineries involved in membrane fusion/fission have been dissected, regulation of membrane dynamics remains poorly understood. The lysosomal vacuole of budding yeast (Saccharomyces cerevisiae) has served as a seminal model in studies of membrane dynamics. We have previously established that yeast ENV7 encodes an ortholog of STK16-related kinases that localizes to the vacuolar membrane and downregulates vacuolar membrane fusion. Additionally, we have previously reported that Env7 phosphorylation in vivo depends on YCK3, a gene that encodes a vacuolar membrane casein kinase I (CKI) homolog that nonredundantly functions in fusion regulation. Here, we report that Env7 physically interacts with and is directly phosphorylated by Yck3. We also establish that Env7 vacuole fusion/fission regulation and vacuolar localization are mediated through its Yck3-dependent phosphorylation. Through extensive site-directed mutagenesis, we map phosphorylation to the Env7 C terminus and confirm that Ser-331 is a primary and preferred phosphorylation site. Phospho-deficient Env7 mutants were defective in negative regulation of membrane fusion, increasing the number of prominent vacuoles, whereas a phosphomimetic substitution at Ser-331 increased the number of fragmented vacuoles. Bioinformatics approaches confirmed that Env7 Ser-331 is within a motif that is highly conserved in STK16-related kinases and that it also anchors an SXXS CKI phosphorylation motif (328SRFS331). This study represents the first report on the regulatory mechanism of an STK16-related kinase. It also points to regulation of vacuolar membrane dynamics via a novel Yck3-Env7 kinase cascade.
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Affiliation(s)
- Surya P Manandhar
- Department of Biological Sciences, California State University at Long Beach, Long Beach, California, USA
| | - Ikha M Siddiqah
- Department of Biological Sciences, California State University at Long Beach, Long Beach, California, USA
| | - Stephanie M Cocca
- Department of Biological Sciences, California State University at Long Beach, Long Beach, California, USA
| | - Editte Gharakhanian
- Department of Biological Sciences, California State University at Long Beach, Long Beach, California, USA.
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22
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Dehnen L, Janz M, Verma JK, Psathaki OE, Langemeyer L, Fröhlich F, Heinisch JJ, Meyer H, Ungermann C, Paululat A. A trimeric metazoan Rab7 GEF complex is crucial for endocytosis and scavenger function. J Cell Sci 2020; 133:jcs247080. [PMID: 32499409 DOI: 10.1242/jcs.247080] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/20/2020] [Indexed: 12/12/2022] Open
Abstract
Endosome biogenesis in eukaryotic cells is critical for nutrient uptake and plasma membrane integrity. Early endosomes initially contain Rab5, which is replaced by Rab7 on late endosomes prior to their fusion with lysosomes. Recruitment of Rab7 to endosomes requires the Mon1-Ccz1 guanine-nucleotide-exchange factor (GEF). Here, we show that full function of the Drosophila Mon1-Ccz1 complex requires a third stoichiometric subunit, termed Bulli (encoded by CG8270). Bulli localises to Rab7-positive endosomes, in agreement with its function in the GEF complex. Using Drosophila nephrocytes as a model system, we observe that absence of Bulli results in (i) reduced endocytosis, (ii) Rab5 accumulation within non-acidified enlarged endosomes, (iii) defective Rab7 localisation and (iv) impaired endosomal maturation. Moreover, longevity of animals lacking bulli is affected. Both the Mon1-Ccz1 dimer and a Bulli-containing trimer display Rab7 GEF activity. In summary, this suggests a key role for Bulli in the Rab5 to Rab7 transition during endosomal maturation rather than a direct influence on the GEF activity of Mon1-Ccz1.
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Affiliation(s)
- Lena Dehnen
- Department of Biology and Chemistry, Zoology and Developmental Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Maren Janz
- Department of Biology and Chemistry, Zoology and Developmental Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Jitender Kumar Verma
- Department of Biology and Chemistry, Biochemistry, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Olympia Ekaterini Psathaki
- Center of Cellular Nanoanalytics, Integrated Bioimaging Facility Osnabrück (iBiOs), University of Osnabrück, 49076 Osnabrück, Germany
| | - Lars Langemeyer
- Department of Biology and Chemistry, Biochemistry, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Florian Fröhlich
- Department of Biology and Chemistry, Molecular Membrane Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Jürgen J Heinisch
- Department of Biology and Chemistry, Genetics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Heiko Meyer
- Department of Biology and Chemistry, Zoology and Developmental Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology and Chemistry, Biochemistry, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
| | - Achim Paululat
- Department of Biology and Chemistry, Zoology and Developmental Biology, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics, University of Osnabrück, Barbarastraße 11, 49076 Osnabrück, Germany
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23
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A Rab prenyl membrane-anchor allows effector recognition to be regulated by guanine nucleotide. Proc Natl Acad Sci U S A 2020; 117:7739-7744. [PMID: 32213587 DOI: 10.1073/pnas.2000923117] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Membrane fusion is catalyzed by conserved proteins R, Qa, Qb, and Qc SNAREs, which form tetrameric RQaQbQc complexes between membranes; SNARE chaperones of the SM, Sec17/αSNAP, and Sec18/NSF families; Rab-GTPases (Rabs); and Rab effectors. Rabs are anchored to membranes by C-terminal prenyl groups, but can also function when anchored by an apolar polypeptide. Rabs are regulated by GTPase-activating proteins (GAPs), activating the hydrolysis of bound GTP. We have reconstituted fusion with pure components from yeast vacuoles including SNAREs, the HOPS (homotypic fusion and vacuole protein sorting) tethering and SNARE-assembly complex, and the Rab Ypt7, bound to membranes by either C-terminal prenyl groups (Ypt7-pr) or a recombinant transmembrane anchor (Ypt7-tm). We now report that HOPS-dependent fusion occurs with Ypt7 anchored by either means, but only Ypt7-pr requires GTP for activation and is inactive either with bound GDP or without bound guanine nucleotide. In contrast, Ypt7-tm is constitutively active for HOPS-dependent fusion, independent of bound guanine nucleotide. Fusion inhibition by the GAP Gyp1-46 is not limited to Ypt7-tm with bound GTP, indicating that this GAP has an additional mode of regulating fusion. Phosphorylation of HOPS by the vacuolar kinase Yck3 renders fusion strictly dependent on GTP-activated Ypt7, whether bound to membranes by prenyl or transmembrane anchor. The binding of GTP or GDP constitutes a selective switch for Ypt7, but with Ypt7-tm, this switch is only read by HOPS after phosphorylation to P-HOPS by its physiological kinase Yck3. The prenyl anchor of Ypt7 allows both HOPS and P-HOPS to be regulated by Ypt7-bound guanine nucleotide.
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24
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Torng T, Song H, Wickner W. Asymmetric Rab activation of vacuolar HOPS to catalyze SNARE complex assembly. Mol Biol Cell 2020; 31:1060-1068. [PMID: 32160129 PMCID: PMC7346727 DOI: 10.1091/mbc.e20-01-0019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Intracellular membrane fusion requires Rab-family GTPases, their effector tethers, soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, and SNARE chaperones of the Sec1/Munc18 (SM), Sec17/α-SNAP, and Sec18/NSF families. We have developed an assay using fluorescence resonance energy transfer to measure SNARE complex formation in real time. We now show that yeast vacuolar SNAREs assemble spontaneously into RQaQbQc complexes when the R- and Qa-SNAREs are concentrated in the same micelles or in cis on the same membrane. When SNAREs are free in solution or are tethered to distinct membranes, assembly requires catalysis by HOPS, the vacuolar SM and tethering complex. The Rab Ypt7 and vacuole lipids together allosterically activate the bound HOPS for catalyzing SNARE assembly, even if none of the SNAREs are membrane bound. HOPS-dependent fusion between proteoliposomes bearing R- or Qa-SNAREs shows a strict requirement for Ypt7 on the R-SNARE proteoliposomes but not on the Qa-SNARE proteoliposomes. This asymmetry is reflected in the strikingly different capacity of Ypt7 in cis to either the R- or Qa-SNARE to stimulate SNARE complex assembly. Membrane-bound Ypt7 activates HOPS to catalyze 4-SNARE complex assembly when it is on the same membrane as the R-SNARE but not the Qa-SNARE, thus explaining the asymmetric need for Ypt7 for fusion.
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Affiliation(s)
- Thomas Torng
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Hongki Song
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - William Wickner
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
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25
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Sparvoli D, Zoltner M, Cheng CY, Field MC, Turkewitz AP. Diversification of CORVET tethers facilitates transport complexity in Tetrahymena thermophila. J Cell Sci 2020; 133:jcs238659. [PMID: 31964712 PMCID: PMC7033735 DOI: 10.1242/jcs.238659] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 01/03/2020] [Indexed: 12/14/2022] Open
Abstract
In endolysosomal networks, two hetero-hexameric tethers called HOPS and CORVET are found widely throughout eukaryotes. The unicellular ciliate Tetrahymena thermophila possesses elaborate endolysosomal structures, but curiously both it and related protozoa lack the HOPS tether and several other trafficking proteins, while retaining the related CORVET complex. Here, we show that Tetrahymena encodes multiple paralogs of most CORVET subunits, which assemble into six distinct complexes. Each complex has a unique subunit composition and, significantly, shows unique localization, indicating participation in distinct pathways. One pair of complexes differ by a single subunit (Vps8), but have late endosomal versus recycling endosome locations. While Vps8 subunits are thus prime determinants for targeting and functional specificity, determinants exist on all subunits except Vps11. This unprecedented expansion and diversification of CORVET provides a potent example of tether flexibility, and illustrates how 'backfilling' following secondary losses of trafficking genes can provide a mechanism for evolution of new pathways.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Daniela Sparvoli
- Department of Molecular Genetics and Cell Biology, 920 E 58th Street, The University of Chicago, Chicago, IL, 60637, USA
| | - Martin Zoltner
- School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Chao-Yin Cheng
- Department of Molecular Genetics and Cell Biology, 920 E 58th Street, The University of Chicago, Chicago, IL, 60637, USA
| | - Mark C Field
- School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, 37005 Ceske Budejovice, Czech Republic
| | - Aaron P Turkewitz
- Department of Molecular Genetics and Cell Biology, 920 E 58th Street, The University of Chicago, Chicago, IL, 60637, USA
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26
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Iadarola DM, Basu Ball W, Trivedi PP, Fu G, Nan B, Gohil VM. Vps39 is required for ethanolamine-stimulated elevation in mitochondrial phosphatidylethanolamine. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158655. [PMID: 32058032 DOI: 10.1016/j.bbalip.2020.158655] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 01/03/2020] [Accepted: 02/04/2020] [Indexed: 12/31/2022]
Abstract
Mitochondrial membrane biogenesis requires the import of phospholipids; however, the molecular mechanisms underlying this process remain elusive. Recent work has implicated membrane contact sites between the mitochondria, endoplasmic reticulum (ER), and vacuole in phospholipid transport. Utilizing a genetic approach focused on these membrane contact site proteins, we have discovered a 'moonlighting' role of the membrane contact site and vesicular fusion protein, Vps39, in phosphatidylethanolamine (PE) transport to the mitochondria. We show that the deletion of Vps39 prevents ethanolamine-stimulated elevation of mitochondrial PE levels without affecting PE biosynthesis in the ER or its transport to other sub-cellular organelles. The loss of Vps39 did not alter the levels of other mitochondrial phospholipids that are biosynthesized ex situ, implying a PE-specific role of Vps39. The abundance of Vps39 and its recruitment to the mitochondria and the ER is dependent on PE levels in each of these organelles, directly implicating Vps39 in the PE transport process. Deletion of essential subunits of Vps39-containing complexes, vCLAMP and HOPS, did not abrogate ethanolamine-stimulated PE elevation in the mitochondria, suggesting an independent role of Vps39 in intracellular PE trafficking. Our work thus identifies Vps39 as a novel player in ethanolamine-stimulated PE transport to the mitochondria.
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Affiliation(s)
- Donna M Iadarola
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Writoban Basu Ball
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Prachi P Trivedi
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA
| | - Guo Fu
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Beiyan Nan
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Vishal M Gohil
- Department of Biochemistry and Biophysics, MS 3474, Texas A&M University, College Station, TX 77843, USA.
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27
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Rodriguez-Furlan C, Minina EA, Hicks GR. Remove, Recycle, Degrade: Regulating Plasma Membrane Protein Accumulation. THE PLANT CELL 2019; 31:2833-2854. [PMID: 31628169 PMCID: PMC6925004 DOI: 10.1105/tpc.19.00433] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/23/2019] [Accepted: 10/17/2019] [Indexed: 05/21/2023]
Abstract
Interactions between plant cells and the environment rely on modulation of protein receptors, transporters, channels, and lipids at the plasma membrane (PM) to facilitate intercellular communication, nutrient uptake, environmental sensing, and directional growth. These functions are fine-tuned by cellular pathways maintaining or reducing particular proteins at the PM. Proteins are endocytosed, and their fate is decided between recycling and degradation to modulate localization, abundance, and activity. Selective autophagy is another pathway regulating PM protein accumulation in response to specific conditions or developmental signals. The mechanisms regulating recycling, degradation, and autophagy have been studied extensively, yet we are just now addressing their regulation and coordination. Here, we (1) provide context concerning regulation of protein accumulation, recycling, or degradation by overviewing endomembrane trafficking; (2) discuss pathways regulating recycling and degradation in terms of cellular roles and cargoes; (3) review plant selective autophagy and its physiological significance; (4) focus on two decision-making mechanisms: regulation of recycling versus degradation of PM proteins and coordination between autophagy and vacuolar degradation; and (5) identify future challenges.
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Affiliation(s)
- Cecilia Rodriguez-Furlan
- Department of Botany and Plant Sciences and Institute of Integrative Genome Biology, University of California, Riverside, California 92506
| | - Elena A Minina
- Uppsala Bio Center, Swedish University of Agricultural Sciences, Uppsala SE-75007, Sweden
- Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
| | - Glenn R Hicks
- Department of Botany and Plant Sciences and Institute of Integrative Genome Biology, University of California, Riverside, California 92506
- Uppsala Bio Center, Swedish University of Agricultural Sciences, Uppsala SE-75007, Sweden
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28
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Sec17 (α-SNAP) and Sec18 (NSF) restrict membrane fusion to R-SNAREs, Q-SNAREs, and SM proteins from identical compartments. Proc Natl Acad Sci U S A 2019; 116:23573-23581. [PMID: 31685636 DOI: 10.1073/pnas.1913985116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Membrane fusion at each organelle requires conserved proteins: Rab-GTPases, effector tethering complexes, Sec1/Munc18 (SM)-family SNARE chaperones, SNAREs of the R, Qa, Qb, and Qc families, and the Sec17/α-SNAP and ATP-dependent Sec18/NSF SNARE chaperone system. The basis of organelle-specific fusion, which is essential for accurate protein compartmentation, has been elusive. Rab family GTPases, SM proteins, and R- and Q-SNAREs may contribute to this specificity. We now report that the fusion supported by SNAREs alone is both inefficient and promiscuous with respect to organelle identity and to stimulation by SM family proteins or complexes. SNARE-only fusion is abolished by the disassembly chaperones Sec17 and Sec18. Efficient fusion in the presence of Sec17 and Sec18 requires a tripartite match between the organellar identities of the R-SNARE, the Q-SNAREs, and the SM protein or complex. The functions of Sec17 and Sec18 are not simply negative regulation; they stimulate fusion with either vacuolar SNAREs and their SM protein complex HOPS or endoplasmic reticulum/cis-Golgi SNAREs and their SM protein Sly1. The fusion complex of each organelle is assembled from its own functionally matching pieces to engage Sec17/Sec18 for fusion stimulation rather than inhibition.
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29
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Rodriguez-Furlan C, Domozych D, Qian W, Enquist PA, Li X, Zhang C, Schenk R, Winbigler HS, Jackson W, Raikhel NV, Hicks GR. Interaction between VPS35 and RABG3f is necessary as a checkpoint to control fusion of late compartments with the vacuole. Proc Natl Acad Sci U S A 2019; 116:21291-21301. [PMID: 31570580 PMCID: PMC6800349 DOI: 10.1073/pnas.1905321116] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Vacuoles are essential organelles in plants, playing crucial roles, such as cellular material degradation, ion and metabolite storage, and turgor maintenance. Vacuoles receive material via the endocytic, secretory, and autophagic pathways. Membrane fusion is the last step during which prevacuolar compartments (PVCs) and autophagosomes fuse with the vacuole membrane (tonoplast) to deliver cargoes. Protein components of the canonical intracellular fusion machinery that are conserved across organisms, including Arabidopsis thaliana, include complexes, such as soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), that catalyze membrane fusion, and homotypic fusion and vacuole protein sorting (HOPS), that serve as adaptors which tether cargo vesicles to target membranes for fusion under the regulation of RAB-GTPases. The mechanisms regulating the recruitment and assembly of tethering complexes are not well-understood, especially the role of RABs in this dynamic regulation. Here, we report the identification of the small synthetic molecule Endosidin17 (ES17), which interferes with synthetic, endocytic, and autophagic traffic by impairing the fusion of late endosome compartments with the tonoplast. Multiple independent target identification techniques revealed that ES17 targets the VPS35 subunit of the retromer tethering complex, preventing its normal interaction with the Arabidopsis RAB7 homolog RABG3f. ES17 interference with VPS35-RABG3f interaction prevents the retromer complex to endosome anchoring, resulting in retention of RABG3f. Using multiple approaches, we show that VPS35-RABG3f-GTP interaction is necessary to trigger downstream events like HOPS complex assembly and fusion of late compartments with the tonoplast. Overall, our results support a role for the interaction of RABG3f-VPS35 as a checkpoint in the control of traffic toward the vacuole.
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Affiliation(s)
- Cecilia Rodriguez-Furlan
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92506
- Institute of Integrative Genome Biology, University of California, Riverside, CA 92506
| | - David Domozych
- Biology Department, Skidmore College, Saratoga Springs, NY 12866
| | - Weixing Qian
- Department of Chemistry, Umea University, SE-901 87 Umea, Sweden
- Department of Chemistry, Chemical Biology Consortium Sweden, SE-901 87 Umea, Sweden
| | - Per-Anders Enquist
- Department of Chemistry, Umea University, SE-901 87 Umea, Sweden
- Department of Chemistry, Chemical Biology Consortium Sweden, SE-901 87 Umea, Sweden
| | - Xiaohui Li
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47906
- Center for Plant Biology, Purdue University, West Lafayette, IN 47906
| | - Chunhua Zhang
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47906
- Center for Plant Biology, Purdue University, West Lafayette, IN 47906
| | - Rolf Schenk
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92506
- Institute of Integrative Genome Biology, University of California, Riverside, CA 92506
| | - Holly Saulsbery Winbigler
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 20201
| | - William Jackson
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 20201
| | - Natasha V Raikhel
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92506
- Institute of Integrative Genome Biology, University of California, Riverside, CA 92506
| | - Glenn R Hicks
- Department of Botany and Plant Sciences, University of California, Riverside, CA 92506;
- Institute of Integrative Genome Biology, University of California, Riverside, CA 92506
- Uppsala BioCenter, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
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30
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Rab GTPases: Switching to Human Diseases. Cells 2019; 8:cells8080909. [PMID: 31426400 PMCID: PMC6721686 DOI: 10.3390/cells8080909] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 02/07/2023] Open
Abstract
Rab proteins compose the largest family of small GTPases and control the different steps of intracellular membrane traffic. More recently, they have been shown to also regulate cell signaling, division, survival, and migration. The regulation of these processes generally occurs through recruitment of effectors and regulatory proteins, which control the association of Rab proteins to membranes and their activation state. Alterations in Rab proteins and their effectors are associated with multiple human diseases, including neurodegeneration, cancer, and infections. This review provides an overview of how the dysregulation of Rab-mediated functions and membrane trafficking contributes to these disorders. Understanding the altered dynamics of Rabs and intracellular transport defects might thus shed new light on potential therapeutic strategies.
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31
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Abstract
R-SNAREs (soluble N-ethylmaleimide-sensitive factor receptor), Q-SNAREs, and Sec1/Munc18 (SM)-family proteins are essential for membrane fusion in exocytic and endocytic trafficking. The yeast vacuolar tethering/SM complex HOPS (homotypic fusion and vacuole protein sorting) increases the fusion of membranes bearing R-SNARE to those with 3Q-SNAREs far more than it enhances their trans-SNARE pairings. We now report that the fusion of these proteoliposomes is also supported by GST-PX or GST-FYVE, recombinant dimeric proteins which tether by binding the phosphoinositides in both membranes. GST-PX is purely a tether, as it supports fusion without SNARE recognition. GST-PX tethering supports the assembly of new, active SNARE complexes rather than enhancing the function of the fusion-inactive SNARE complexes which had spontaneously formed in the absence of a tether. When SNAREs are more disassembled, as by Sec17, Sec18, and ATP (adenosine triphosphate), HOPS is required, and GST-PX does not suffice. We propose a working model where tethering orients SNARE domains for parallel, active assembly.
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32
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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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33
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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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34
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Kriegenburg F, Bas L, Gao J, Ungermann C, Kraft C. The multi-functional SNARE protein Ykt6 in autophagosomal fusion processes. Cell Cycle 2019; 18:639-651. [PMID: 30836834 PMCID: PMC6464585 DOI: 10.1080/15384101.2019.1580488] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/06/2019] [Accepted: 01/29/2019] [Indexed: 01/01/2023] Open
Abstract
Autophagy is a degradative pathway in which cytosolic material is enwrapped within double membrane vesicles, so-called autophagosomes, and delivered to lytic organelles. SNARE (Soluble N-ethylmaleimide sensitive factor attachment protein receptor) proteins are key to drive membrane fusion of the autophagosome and the lytic organelles, called lysosomes in higher eukaryotes or vacuoles in plants and yeast. Therefore, the identification of functional SNARE complexes is central for understanding fusion processes and their regulation. The SNARE proteins Syntaxin 17, SNAP29 and Vamp7/VAMP8 are responsible for the fusion of autophagosomes with lysosomes in higher eukaryotes. Recent studies reported that the R-SNARE Ykt6 is an additional SNARE protein involved in autophagosome-lytic organelle fusion in yeast, Drosophila, and mammals. These current findings point to an evolutionarily conserved role of Ykt6 in autophagosome-related fusion events. Here, we briefly summarize the principal mechanisms of autophagosome-lytic organelle fusion, with a special focus on Ykt6 to highlight some intrinsic features of this unusual SNARE protein.
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Affiliation(s)
- Franziska Kriegenburg
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Levent Bas
- Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, Vienna, Austria
| | - Jieqiong Gao
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Christian Ungermann
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
- Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Claudine Kraft
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, Vienna, Austria
- CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg
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35
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Chen LL, Huang YJ, Cui JT, Song N, Xie J. Iron Dysregulation in Parkinson's Disease: Focused on the Autophagy-Lysosome Pathway. ACS Chem Neurosci 2019; 10:863-871. [PMID: 30590010 DOI: 10.1021/acschemneuro.8b00390] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disease and is characterized by dopaminergic neuron loss in the substantia nigra pars compacta (SNpc). Although both iron accumulation and a defective autophagy-lysosome pathway contribute to the pathological development of PD, the connection between these two causes is poorly documented. The autophagy-lysosome pathway not only responds to regulation by iron chelators and channels but also participates in cellular iron recycling through the degradation of ferritin and other iron-containing components. Previously, ferritin has been posited to be the bridge between iron accumulation and autophagy impairment in PD. In addition, iron directly interacts with α-synuclein in Lewy bodies, which are primarily digested through the autophagy-lysosome pathway. These findings indicate that some link exists between iron deposition and autophagy impairment in PD. In this review, the basic mechanisms of the autophagy-lysosome pathway and iron trafficking are introduced, and then their interaction under physiological conditions is explained. Finally, we finish by discussing the dysfunction of iron deposition and autophagy in PD, as well as their potential relationship, which will provide some insight for further study.
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Affiliation(s)
- Lei-Lei Chen
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, Shandong 266071, China
| | - Yu-Jv Huang
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, Shandong 266071, China
| | - Jun-tao Cui
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, Shandong 266071, China
| | - Ning Song
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, Shandong 266071, China
| | - Junxia Xie
- Institute of Brain Science and Disease, Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders, Qingdao University, Qingdao, Shandong 266071, China
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36
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Abstract
The Golgi apparatus is a central sorting station in the cell. It receives newly synthesized molecules from the endoplasmic reticulum and directs them to different subcellular destinations, such as the plasma membrane or the endocytic pathway. Importantly, in the last few years, it has emerged that the maintenance of Golgi structure is connected to the proper regulation of membrane trafficking. Rab proteins are small GTPases that are considered to be the master regulators of the intracellular membrane trafficking. Several of the over 60 human Rabs are involved in the regulation of transport pathways at the Golgi as well as in the maintenance of its architecture. This chapter will summarize the different roles of Rab GTPases at the Golgi, both as regulators of membrane transport, scaffold, and tethering proteins and in preserving the structure and function of this organelle.
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37
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Karim MA, McNally EK, Samyn DR, Mattie S, Brett CL. Rab-Effector-Kinase Interplay Modulates Intralumenal Fragment Formation during Vacuole Fusion. Dev Cell 2018; 47:80-97.e6. [PMID: 30269949 DOI: 10.1016/j.devcel.2018.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 07/01/2018] [Accepted: 09/01/2018] [Indexed: 01/17/2023]
Abstract
Upon vacuolar lysosome (or vacuole) fusion in S. cerevisiae, a portion of membrane is internalized and catabolized. Formation of this intralumenal fragment (ILF) is important for organelle protein and lipid homeostasis and remodeling. But how ILF formation is optimized for membrane turnover is not understood. Here, we show that fewer ILFs form when the interaction between the Rab-GTPase Ypt7 and its effector Vps41 (a subunit of the tethering complex HOPS) is interrupted by a point mutation (Ypt7-D44N). Subsequent phosphorylation of Vps41 by the casein kinase Yck3 prevents stabilization of trans-SNARE complexes needed for lipid bilayer pore formation. Impairing ILF formation prevents clearance of misfolded proteins from vacuole membranes and promotes organelle permeability and cell death. We propose that HOPS coordinates Rab, kinase, and SNARE cycles to modulate ILF size during vacuole fusion, regulating lipid and protein turnover important for quality control and membrane integrity.
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Affiliation(s)
- Mahmoud Abdul Karim
- Department of Biology, Concordia University, 7141 Sherbrooke St. W., SP, 501.15, Montréal, QC H4R 1R6, Canada
| | - Erin Kate McNally
- Department of Biology, Concordia University, 7141 Sherbrooke St. W., SP, 501.15, Montréal, QC H4R 1R6, Canada
| | - Dieter Ronny Samyn
- Department of Biology, Concordia University, 7141 Sherbrooke St. W., SP, 501.15, Montréal, QC H4R 1R6, Canada
| | - Sevan Mattie
- Department of Biology, Concordia University, 7141 Sherbrooke St. W., SP, 501.15, Montréal, QC H4R 1R6, Canada
| | - Christopher Leonard Brett
- Department of Biology, Concordia University, 7141 Sherbrooke St. W., SP, 501.15, Montréal, QC H4R 1R6, Canada.
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38
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D'Agostino M, Risselada HJ, Endter LJ, Comte-Miserez V, Mayer A. SNARE-mediated membrane fusion arrests at pore expansion to regulate the volume of an organelle. EMBO J 2018; 37:embj.201899193. [PMID: 30120144 DOI: 10.15252/embj.201899193] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 06/28/2018] [Accepted: 07/03/2018] [Indexed: 11/09/2022] Open
Abstract
Constitutive membrane fusion within eukaryotic cells is thought to be controlled at its initial steps, membrane tethering and SNARE complex assembly, and to rapidly proceed from there to full fusion. Although theory predicts that fusion pore expansion faces a major energy barrier and might hence be a rate-limiting and regulated step, corresponding states with non-expanding pores are difficult to assay and have remained elusive. Here, we show that vacuoles in living yeast are connected by a metastable, non-expanding, nanoscopic fusion pore. This is their default state, from which full fusion is regulated. Molecular dynamics simulations suggest that SNAREs and the SM protein-containing HOPS complex stabilize this pore against re-closure. Expansion of the nanoscopic pore to full fusion can thus be triggered by osmotic pressure gradients, providing a simple mechanism to rapidly adapt organelle volume to increases in its content. Metastable, nanoscopic fusion pores are then not only a transient intermediate but can be a long-lived, physiologically relevant and regulated state of SNARE-dependent membrane fusion.
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Affiliation(s)
- Massimo D'Agostino
- Département de Biochimie, Université de Lausanne, Epalinges, Switzerland
| | - Herre Jelger Risselada
- Department of Theoretical Physics, Georg-August University, Göttingen, Germany.,Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | - Laura J Endter
- Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
| | | | - Andreas Mayer
- Département de Biochimie, Université de Lausanne, Epalinges, Switzerland
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39
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Gao J, Reggiori F, Ungermann C. A novel in vitro assay reveals SNARE topology and the role of Ykt6 in autophagosome fusion with vacuoles. J Cell Biol 2018; 217:3670-3682. [PMID: 30097515 PMCID: PMC6168247 DOI: 10.1083/jcb.201804039] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/13/2018] [Accepted: 07/06/2018] [Indexed: 11/22/2022] Open
Abstract
Autophagosome fusion with vacuoles requires a conserved fusion machinery, though the topology remained unclear. Two papers in this issue, Bas et al. and Gao et al., uncover Ykt6 as the required autophagosomal SNARE. Autophagy is a catabolic pathway that delivers intracellular material to the mammalian lysosomes or the yeast and plant vacuoles. The final step in this process is the fusion of autophagosomes with vacuoles, which requires SNARE proteins, the homotypic vacuole fusion and protein sorting tethering complex, the RAB7-like Ypt7 GTPase, and its guanine nucleotide exchange factor, Mon1-Ccz1. Where these different components are located and function during fusion, however, remains to be fully understood. Here, we present a novel in vitro assay to monitor fusion of intact and functional autophagosomes with vacuoles. This process requires ATP, physiological temperature, and the entire fusion machinery to tether and fuse autophagosomes with vacuoles. Importantly, we uncover Ykt6 as the autophagosomal SNARE. Our assay and findings thus provide the tools to dissect autophagosome completion and fusion in a test tube.
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Affiliation(s)
- Jieqiong Gao
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Christian Ungermann
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany .,Center of Cellular Nanoanalytics Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
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40
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Kjos I, Vestre K, Guadagno NA, Borg Distefano M, Progida C. Rab and Arf proteins at the crossroad between membrane transport and cytoskeleton dynamics. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2018; 1865:1397-1409. [PMID: 30021127 DOI: 10.1016/j.bbamcr.2018.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 07/05/2018] [Accepted: 07/13/2018] [Indexed: 01/04/2023]
Abstract
The intracellular movement and positioning of organelles and vesicles is mediated by the cytoskeleton and molecular motors. Small GTPases like Rab and Arf proteins are main regulators of intracellular transport by connecting membranes to cytoskeleton motors or adaptors. However, it is becoming clear that interactions between these small GTPases and the cytoskeleton are important not only for the regulation of membrane transport. In this review, we will cover our current understanding of the mechanisms underlying the connection between Rab and Arf GTPases and the cytoskeleton, with special emphasis on the double role of these interactions, not only in membrane trafficking but also in membrane and cytoskeleton remodeling. Furthermore, we will highlight the most recent findings about the fine control mechanisms of crosstalk between different members of Rab, Arf, and Rho families of small GTPases in the regulation of cytoskeleton organization.
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Affiliation(s)
- Ingrid Kjos
- Department of Biosciences, University of Oslo, Norway
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41
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Langemeyer L, Fröhlich F, Ungermann C. Rab GTPase Function in Endosome and Lysosome Biogenesis. Trends Cell Biol 2018; 28:957-970. [PMID: 30025982 DOI: 10.1016/j.tcb.2018.06.007] [Citation(s) in RCA: 237] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/15/2018] [Accepted: 06/25/2018] [Indexed: 10/28/2022]
Abstract
Eukaryotic cells maintain a highly organized endolysosomal system. This system regulates the protein and lipid content of the plasma membrane, it participates in the intracellular quality control machinery and is needed for the efficient removal of damaged organelles. This complex network comprises an endosomal membrane system that feeds into the lysosomes, yet also allows recycling of membrane proteins, and probably lipids. Moreover, lysosomal degradation provides the cell with macromolecules for further growth. In this review, we focus primarily on the role of the small Rab GTPases Rab5 and Rab7 as organelle markers and interactors of multiple effectors on endosomes and lysosomes and highlight their role in membrane dynamics, particularly fusion along the endolysosomal pathway.
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Affiliation(s)
- Lars Langemeyer
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany
| | - Florian Fröhlich
- Department of Biology/Chemistry, Molecular Membrane Biology Group, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany; Center of Cellular Nanoanalytics of the University of Osnabrück (CellNanOs), Barbarastrasse 11, 49076 Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany; Department of Biology/Chemistry, Molecular Membrane Biology Group, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany; Center of Cellular Nanoanalytics of the University of Osnabrück (CellNanOs), Barbarastrasse 11, 49076 Osnabrück, Germany.
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42
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González Montoro A, Auffarth K, Hönscher C, Bohnert M, Becker T, Warscheid B, Reggiori F, van der Laan M, Fröhlich F, Ungermann C. Vps39 Interacts with Tom40 to Establish One of Two Functionally Distinct Vacuole-Mitochondria Contact Sites. Dev Cell 2018; 45:621-636.e7. [PMID: 29870720 DOI: 10.1016/j.devcel.2018.05.011] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 04/13/2018] [Accepted: 05/06/2018] [Indexed: 11/29/2022]
Abstract
The extensive subcellular network of membrane contact sites plays central roles in organelle biogenesis and communication, yet the precise contributions of the involved machineries remain largely enigmatic. The yeast vacuole forms a membrane contact site with mitochondria, called vacuolar and mitochondrial patch (vCLAMP). Formation of vCLAMPs involves the vacuolar Rab GTPase Ypt7 and the Ypt7-interacting Vps39 subunit of the HOPS tethering complex. Here, we uncover the general preprotein translocase of the outer membrane (TOM) subunit Tom40 as the direct binding partner of Vps39 on mitochondria. We identify Vps39 mutants defective in TOM binding, but functional for HOPS. Cells that cannot form vCLAMPs show reduced growth under stress conditions and impaired survival upon starvation. Unexpectedly, our mutant analysis revealed the existence of two functionally independent vacuole-mitochondria MCSs: one formed by the Ypt7-Vps39-Tom40 tether and a second one by Vps13-Mcp1, which is redundant with ER-mitochondrial contacts formed by ERMES.
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Affiliation(s)
- Ayelén González Montoro
- Department of Biology/Chemistry, Biochemistry Section University of Osnabrück, Barbarastrasse 13, Osnabrück 49076, Germany.
| | - Kathrin Auffarth
- Department of Biology/Chemistry, Biochemistry Section University of Osnabrück, Barbarastrasse 13, Osnabrück 49076, Germany
| | - Carina Hönscher
- Department of Biology/Chemistry, Biochemistry Section University of Osnabrück, Barbarastrasse 13, Osnabrück 49076, Germany
| | - Maria Bohnert
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany; Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg 79104, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg 79104, Germany
| | - Bettina Warscheid
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg 79104, Germany; Institute of Biology II, Department of Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, Groningen 9713 AV, the Netherlands
| | - Martin van der Laan
- Department of Medical Biochemistry & Molecular Biology, Center for Molecular Signaling, PZMS, Faculty of Medicine, Saarland University, Homburg 66421, Germany
| | - Florian Fröhlich
- Department of Biology/Chemistry, Molecular Membrane Biology Section, University of Osnabrück, Barbarastrasse 13, Osnabrück 49076, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section University of Osnabrück, Barbarastrasse 13, Osnabrück 49076, Germany.
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43
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Abstract
The lysosome-like vacuole is the main organelle to degrade membrane proteins and organelles and, thus, provides amino acids, but also ions to the cytosol for cellular survival. Maintenance of vacuole membrane integrity is thus important for cellular adaptations. The vacuole contains several protein complexes on its surface to maintain the vacuole functional, and one such complex is a lipid kinase named Fab1 (of PIKfyve in human cells). Fab1 is part of a protein complex that produces a phosphorylated lipid, PI-3,5-P2. Other proteins bind PI-3,5-P2 and can fragment the vacuole to balance volume vs. membrane during stress. We now identify Ivy1 as a protein that binds Fab1 and controls its activity. Lysosomes have an important role in cellular protein and organelle quality control, metabolism, and signaling. On the surface of lysosomes, the PIKfyve/Fab1 complex generates phosphatidylinositol 3,5-bisphosphate, PI-3,5-P2, which is critical for lysosomal membrane homeostasis during acute osmotic stress and for lysosomal signaling. Here, we identify the inverted BAR protein Ivy1 as an inhibitor of the Fab1 complex with a direct influence on PI-3,5-P2 levels and vacuole homeostasis. Ivy1 requires Ypt7 binding for its function, binds PI-3,5-P2, and interacts with the Fab1 kinase. Colocalization of Ivy1 and Fab1 is lost during osmotic stress. In agreement with Ivy1’s role as a Fab1 regulator, its overexpression blocks Fab1 activity during osmotic shock and vacuole fragmentation. Conversely, loss of Ivy1, or lateral relocalization of Ivy1 on vacuoles away from Fab1, results in vacuole fragmentation and poor growth. Our data suggest that Ivy1 modulates Fab1-mediated PI-3,5-P2 synthesis during membrane stress and may allow adjustment of the vacuole membrane environment.
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44
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Pylypenko O, Hammich H, Yu IM, Houdusse A. Rab GTPases and their interacting protein partners: Structural insights into Rab functional diversity. Small GTPases 2018. [PMID: 28632484 DOI: 10.1080/215412481336191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023] Open
Abstract
Rab molecular switches are key players in defining membrane identity and regulating intracellular trafficking events in eukaryotic cells. In spite of their global structural similarity, Rab-family members acquired particular features that allow them to perform specific cellular functions. The overall fold and local sequence conservations enable them to utilize a common machinery for prenylation and recycling; while individual Rab structural differences determine interactions with specific partners such as GEFs, GAPs and effector proteins. These interactions orchestrate the spatiotemporal regulation of Rab localization and their turning ON and OFF, leading to tightly controlled Rab-specific functionalities such as membrane composition modifications, recruitment of molecular motors for intracellular trafficking, or recruitment of scaffold proteins that mediate interactions with downstream partners, as well as actin cytoskeleton regulation. In this review we summarize structural information on Rab GTPases and their complexes with protein partners in the context of partner binding specificity and functional outcomes of their interactions in the cell.
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Affiliation(s)
- Olena Pylypenko
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
| | - Hussein Hammich
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
- b Sorbonne Universités , UPMC Univ Paris 06, Sorbonne Universités, IFD , Paris , France
| | - I-Mei Yu
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
| | - Anne Houdusse
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
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45
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Sparvoli D, Richardson E, Osakada H, Lan X, Iwamoto M, Bowman GR, Kontur C, Bourland WA, Lynn DH, Pritchard JK, Haraguchi T, Dacks JB, Turkewitz AP. Remodeling the Specificity of an Endosomal CORVET Tether Underlies Formation of Regulated Secretory Vesicles in the Ciliate Tetrahymena thermophila. Curr Biol 2018; 28:697-710.e13. [PMID: 29478853 DOI: 10.1016/j.cub.2018.01.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 12/09/2017] [Accepted: 01/17/2018] [Indexed: 12/14/2022]
Abstract
In the endocytic pathway of animals, two related complexes, called CORVET (class C core vacuole/endosome transport) and HOPS (homotypic fusion and protein sorting), act as both tethers and fusion factors for early and late endosomes, respectively. Mutations in CORVET or HOPS lead to trafficking defects and contribute to human disease, including immune dysfunction. HOPS and CORVET are conserved throughout eukaryotes, but remarkably, in the ciliate Tetrahymena thermophila, the HOPS-specific subunits are absent, while CORVET-specific subunits have proliferated. VPS8 (vacuolar protein sorting), a CORVET subunit, expanded to 6 paralogs in Tetrahymena. This expansion correlated with loss of HOPS within a ciliate subgroup, including the Oligohymenophorea, which contains Tetrahymena. As uncovered via forward genetics, a single VPS8 paralog in Tetrahymena (VPS8A) is required to synthesize prominent secretory granules called mucocysts. More specifically, Δvps8a cells fail to deliver a subset of cargo proteins to developing mucocysts, instead accumulating that cargo in vesicles also bearing the mucocyst-sorting receptor Sor4p. Surprisingly, although this transport step relies on CORVET, it does not appear to involve early endosomes. Instead, Vps8a associates with the late endosomal/lysosomal marker Rab7, indicating that target specificity switching occurred in CORVET subunits during the evolution of ciliates. Mucocysts belong to a markedly diverse and understudied class of protist secretory organelles called extrusomes. Our results underscore that biogenesis of mucocysts depends on endolysosomal trafficking, revealing parallels with invasive organelles in apicomplexan parasites and suggesting that a wide array of secretory adaptations in protists, like in animals, depend on mechanisms related to lysosome biogenesis.
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Affiliation(s)
- Daniela Sparvoli
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA
| | | | - Hiroko Osakada
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Xun Lan
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Masaaki Iwamoto
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan
| | - Grant R Bowman
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA
| | - Cassandra Kontur
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA
| | - William A Bourland
- Department of Biological Sciences, Boise State University, Boise, ID 83725-1515, USA
| | - Denis H Lynn
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Jonathan K Pritchard
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Tokuko Haraguchi
- Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Joel B Dacks
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Aaron P Turkewitz
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL, USA.
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Gao J, Langemeyer L, Kümmel D, Reggiori F, Ungermann C. Molecular mechanism to target the endosomal Mon1-Ccz1 GEF complex to the pre-autophagosomal structure. eLife 2018; 7:31145. [PMID: 29446751 PMCID: PMC5841931 DOI: 10.7554/elife.31145] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 02/12/2018] [Indexed: 11/13/2022] Open
Abstract
During autophagy, a newly formed double membrane surrounds its cargo to generate the so-called autophagosome, which then fuses with a lysosome after closure. Previous work implicated that endosomal Rab7/Ypt7 associates to autophagosomes prior to their fusion with lysosomes. Here, we unravel how the Mon1-Ccz1 guanosine exchange factor (GEF) acting upstream of Ypt7 is specifically recruited to the pre-autophagosomal structure under starvation conditions. We find that Mon1-Ccz1 directly binds to Atg8, the yeast homolog of the members of the mammalian LC3 protein family. This requires at least one LIR motif in the Ccz1 C-terminus, which is essential for autophagy but not for endosomal transport. In agreement, only wild-type, but not LIR-mutated Mon1-Ccz1 promotes Atg8-dependent activation of Ypt7. Our data reveal how GEF targeting can specify the fate of a newly formed organelle and provide new insights into the regulation of autophagosome-lysosome fusion. Autophagy is a word derived from the Greek for “self-eating”. It describes a biological process in which a living cell breaks down its own material to release their chemical building blocks that can then be used to make new molecules. Autophagy is often triggered when a cell becomes damaged or when nutrients are in short supply. The hallmark of autophagy is the formation of structures called autophagosomes. These structures capture the cellular material, fuse with other compartments in the cell – namely endosomes in animals and vacuoles in yeast – and then deliver the material inside, ready to be broken down. For an autophagosome to fuse to an endosome or a vacuole, small proteins of the Rab protein family must be located on the surface of the autophagosome. Rab proteins are recruited to this surface by enzymes known as GEFs. However it remains unclear how most GEFs get to the surface of a compartment within the cell to begin with. The Mon1-Ccz1 complex is a GEF that occurs in yeast and animals, including fruit flies and humans. It is found on endosomes, and was recently shown to also localize to autophagosomes. Now, Gao et al. report that, in yeast, the Mon1-Ccz1 complex binds directly to a protein named Atg8. This protein is anchored on to the surface of autophagosomes, and is closely related to other proteins in animal cells. Gao et al. discovered that this specific GEF binds to Atg8 via at least one binding site on its Ccz1 component. This binding site is only needed for the GEF to localize to the autophagosomes; the Mon1-Czz1 complex can still bind to endosomes without it. Blocking the GEF from binding to Atg8 stopped the autophagosomes from fusing with vacuoles. These findings reveal how a GEF can be targeted to two distinct compartments in the cell: endosomes and autophagosomes. Further work is now needed to understand how this process is regulated by the availability of nutrients or damage to the cell, to ensure that autophagy is only triggered under the right conditions. Also, because cancer cells often rely on autophagy to survive, the molecules that regulate this process could represent possible targets for new anticancer drugs.
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Affiliation(s)
- Jieqiong Gao
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Lars Langemeyer
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Daniel Kümmel
- Structural Biology Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Christian Ungermann
- Biochemistry Section, Department of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
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47
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Yu L, Chen Y, Tooze SA. Autophagy pathway: Cellular and molecular mechanisms. Autophagy 2017; 14:207-215. [PMID: 28933638 PMCID: PMC5902171 DOI: 10.1080/15548627.2017.1378838] [Citation(s) in RCA: 916] [Impact Index Per Article: 130.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 08/04/2017] [Accepted: 09/07/2017] [Indexed: 02/06/2023] Open
Abstract
Macroautophagy/autophagy is an essential, conserved self-eating process that cells perform to allow degradation of intracellular components, including soluble proteins, aggregated proteins, organelles, macromolecular complexes, and foreign bodies. The process requires formation of a double-membrane structure containing the sequestered cytoplasmic material, the autophagosome, that ultimately fuses with the lysosome. This review will define this process and the cellular pathways required, from the formation of the double membrane to the fusion with lysosomes in molecular terms, and in particular highlight the recent progress in our understanding of this complex process.
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Affiliation(s)
- Li Yu
- State Key Laboratory of Membrane Biology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yang Chen
- State Key Laboratory of Membrane Biology, Tsinghua University-Peking University Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Sharon A. Tooze
- Molecular Cell Biology of Autophagy, The Francis Crick Institute, London, United Kingdom
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Langemeyer L, Perz A, Kümmel D, Ungermann C. A guanine nucleotide exchange factor (GEF) limits Rab GTPase-driven membrane fusion. J Biol Chem 2017; 293:731-739. [PMID: 29184002 DOI: 10.1074/jbc.m117.812941] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 11/14/2017] [Indexed: 11/06/2022] Open
Abstract
The identity of organelles in the endomembrane system of any eukaryotic cell critically depends on the correctly localized Rab GTPase, which binds effectors and thus promotes membrane remodeling or fusion. However, it is still unresolved which factors are required and therefore define the localization of the correct fusion machinery. Using SNARE-decorated proteoliposomes that cannot fuse on their own, we now demonstrate that full fusion activity can be achieved by just four soluble factors: a soluble SNARE (Vam7), a guanine nucleotide exchange factor (GEF, Mon1-Ccz1), a Rab-GDP dissociation inhibitor (GDI) complex (prenylated Ypt7-GDI), and a Rab effector complex (HOPS). Our findings reveal that the GEF Mon1-Ccz1 is necessary and sufficient for stabilizing prenylated Ypt7 on membranes. HOPS binding to Ypt7-GTP then drives SNARE-mediated fusion, which is fully GTP-dependent. We conclude that an entire fusion cascade can be controlled by a GEF.
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Affiliation(s)
| | | | - Daniel Kümmel
- Structural Biochemistry, Department of Biology/Chemistry, University of Osnabrück, Barbarastrasse 13, 49076 Osnabrück, Germany
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49
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D'Agostino M, Risselada HJ, Lürick A, Ungermann C, Mayer A. A tethering complex drives the terminal stage of SNARE-dependent membrane fusion. Nature 2017; 551:634-638. [PMID: 29088698 DOI: 10.1038/nature24469] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 10/03/2017] [Indexed: 11/09/2022]
Abstract
Membrane fusion in eukaryotic cells mediates the biogenesis of organelles, vesicular traffic between them, and exo- and endocytosis of important signalling molecules, such as hormones and neurotransmitters. Distinct tasks in intracellular membrane fusion have been assigned to conserved protein systems. Tethering proteins mediate the initial recognition and attachment of membranes, whereas SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) protein complexes are considered as the core fusion engine. SNARE complexes provide mechanical energy to distort membranes and drive them through a hemifusion intermediate towards the formation of a fusion pore. This last step is highly energy-demanding. Here we combine the in vivo and in vitro fusion of yeast vacuoles with molecular simulations to show that tethering proteins are critical for overcoming the final energy barrier to fusion pore formation. SNAREs alone drive vacuoles only into the hemifused state. Tethering proteins greatly increase the volume of SNARE complexes and deform the site of hemifusion, which lowers the energy barrier for pore opening and provides the driving force. Thereby, tethering proteins assume a crucial mechanical role in the terminal stage of membrane fusion that is likely to be conserved at multiple steps of vesicular traffic. We therefore propose that SNAREs and tethering proteins should be considered as a single, non-dissociable device that drives fusion. The core fusion machinery may then be larger and more complex than previously thought.
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Affiliation(s)
- Massimo D'Agostino
- Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
| | - Herre Jelger Risselada
- Georg-August University, Department of Theoretical Physics, Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.,Leibniz Institute of Surface Modification, Chemical Department, Permoserstrasse 15, D-04318, Leipzig, Germany
| | - Anna Lürick
- University of Osnabrück, Department of Biology/Chemistry, Barbarastrasse 13, D-49076 Osnabrück, Germany
| | - Christian Ungermann
- University of Osnabrück, Department of Biology/Chemistry, Barbarastrasse 13, D-49076 Osnabrück, Germany
| | - Andreas Mayer
- Département de Biochimie, Université de Lausanne, Chemin des Boveresses 155, CH-1066 Epalinges, Switzerland
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50
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Pylypenko O, Hammich H, Yu IM, Houdusse A. Rab GTPases and their interacting protein partners: Structural insights into Rab functional diversity. Small GTPases 2017. [PMID: 28632484 PMCID: PMC5902227 DOI: 10.1080/21541248.2017.1336191] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Rab molecular switches are key players in defining membrane identity and regulating intracellular trafficking events in eukaryotic cells. In spite of their global structural similarity, Rab-family members acquired particular features that allow them to perform specific cellular functions. The overall fold and local sequence conservations enable them to utilize a common machinery for prenylation and recycling; while individual Rab structural differences determine interactions with specific partners such as GEFs, GAPs and effector proteins. These interactions orchestrate the spatiotemporal regulation of Rab localization and their turning ON and OFF, leading to tightly controlled Rab-specific functionalities such as membrane composition modifications, recruitment of molecular motors for intracellular trafficking, or recruitment of scaffold proteins that mediate interactions with downstream partners, as well as actin cytoskeleton regulation. In this review we summarize structural information on Rab GTPases and their complexes with protein partners in the context of partner binding specificity and functional outcomes of their interactions in the cell.
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Affiliation(s)
- Olena Pylypenko
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
| | - Hussein Hammich
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France.,b Sorbonne Universités , UPMC Univ Paris 06, Sorbonne Universités, IFD , Paris , France
| | - I-Mei Yu
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
| | - Anne Houdusse
- a Structural Motility, Institut Curie , PSL Research University, CNRS, UMR 144 , Paris , France
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