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Kazan JM, Desrochers G, Martin CE, Jeong H, Kharitidi D, Apaja PM, Roldan A, St. Denis N, Gingras AC, Lukacs GL, Pause A. Endofin is required for HD-PTP and ESCRT-0 interdependent endosomal sorting of ubiquitinated transmembrane cargoes. iScience 2021; 24:103274. [PMID: 34761192 PMCID: PMC8567383 DOI: 10.1016/j.isci.2021.103274] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/18/2021] [Accepted: 10/12/2021] [Indexed: 11/20/2022] Open
Abstract
Internalized and ubiquitinated signaling receptors are silenced by their intraluminal budding into multivesicular bodies aided by the endosomal sorting complexes required for transport (ESCRT) machinery. HD-PTP, an ESCRT protein, forms complexes with ESCRT-0, -I and -III proteins, and binds to Endofin, a FYVE-domain protein confined to endosomes with poorly understood roles. Using proximity biotinylation, we showed that Endofin forms a complex with ESCRT constituents and Endofin depletion increased integrin α5-and EGF-receptor plasma membrane density and stability by hampering their lysosomal delivery. This coincided with sustained receptor signaling and increased cell migration. Complementation of Endofin- or HD-PTP-depleted cells with wild-type Endofin or HD-PTP, but not with mutants harboring impaired Endofin/HD-PTP association or cytosolic Endofin, restored EGFR lysosomal delivery. Endofin also promoted Hrs indirect interaction with HD-PTP. Jointly, our results indicate that Endofin is required for HD-PTP and ESCRT-0 interdependent sorting of ubiquitinated transmembrane cargoes to ensure efficient receptor desensitization and lysosomal delivery.
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Affiliation(s)
- Jalal M. Kazan
- Goodman Cancer Research Center, McGill University, Montreal, QC H3A 1A3, Canada
- Biochemistry Department, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Guillaume Desrochers
- Goodman Cancer Research Center, McGill University, Montreal, QC H3A 1A3, Canada
- Biochemistry Department, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Claire E. Martin
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Hyeonju Jeong
- Goodman Cancer Research Center, McGill University, Montreal, QC H3A 1A3, Canada
- Biochemistry Department, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Dmitri Kharitidi
- Goodman Cancer Research Center, McGill University, Montreal, QC H3A 1A3, Canada
- Biochemistry Department, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Pirjo M. Apaja
- Physiology Department, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Ariel Roldan
- Physiology Department, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Nicole St. Denis
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, ON M5G 1X5, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Gergely L. Lukacs
- Biochemistry Department, McGill University, Montreal, QC H3G 1Y6, Canada
- Physiology Department, McGill University, Montreal, QC H3G 1Y6, Canada
| | - Arnim Pause
- Goodman Cancer Research Center, McGill University, Montreal, QC H3A 1A3, Canada
- Biochemistry Department, McGill University, Montreal, QC H3G 1Y6, Canada
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Roach TG, Lång HKM, Xiong W, Ryhänen SJ, Capelluto DGS. Protein Trafficking or Cell Signaling: A Dilemma for the Adaptor Protein TOM1. Front Cell Dev Biol 2021; 9:643769. [PMID: 33718385 PMCID: PMC7952518 DOI: 10.3389/fcell.2021.643769] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/09/2021] [Indexed: 12/29/2022] Open
Abstract
Lysosomal degradation of ubiquitinated transmembrane protein receptors (cargo) relies on the function of Endosomal Sorting Complex Required for Transport (ESCRT) protein complexes. The ESCRT machinery is comprised of five unique oligomeric complexes with distinct functions. Target of Myb1 (TOM1) is an ESCRT protein involved in the initial steps of endosomal cargo sorting. To exert its function, TOM1 associates with ubiquitin moieties on the cargo via its VHS and GAT domains. Several ESCRT proteins, including TOLLIP, Endofin, and Hrs, have been reported to form a complex with TOM1 at early endosomal membrane surfaces, which may potentiate the role of TOM1 in cargo sorting. More recently, it was found that TOM1 is involved in other physiological processes, including autophagy, immune responses, and neuroinflammation, which crosstalk with its endosomal cargo sorting function. Alteration of TOM1 function has emerged as a phosphoinositide-dependent survival mechanism for bacterial infections and cancer progression. Based on current knowledge of TOM1-dependent cellular processes, this review illustrates how TOM1 functions in coordination with an array of protein partners under physiological and pathological scenarios.
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Affiliation(s)
- Tiffany G. Roach
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute, and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, United States
| | - Heljä K. M. Lång
- Division of Hematology, Oncology, and Stem Cell Transplantation, Children’s Hospital, and Pediatric Research Center, The New Children’s Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Wen Xiong
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute, and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, United States
| | - Samppa J. Ryhänen
- Division of Hematology, Oncology, and Stem Cell Transplantation, Children’s Hospital, and Pediatric Research Center, The New Children’s Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Daniel G. S. Capelluto
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute, and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, United States
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3
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LC3C-Mediated Autophagy Selectively Regulates the Met RTK and HGF-Stimulated Migration and Invasion. Cell Rep 2020; 29:4053-4068.e6. [PMID: 31851933 DOI: 10.1016/j.celrep.2019.11.063] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 09/18/2019] [Accepted: 11/14/2019] [Indexed: 12/15/2022] Open
Abstract
The Met/hepatocyte growth factor (HGF) receptor tyrosine kinase (RTK) is deregulated in many cancers and is a recognized target for cancer therapies. Following HGF stimulation, the signaling output of Met is tightly controlled by receptor internalization and sorting for degradation or recycling. Here, we uncover a role for autophagy in selective degradation of Met and regulation of Met-dependent cell migration and invasion. Met engagement with the autophagic pathway is dependent on complex formation with the mammalian ATG8 family member MAP1LC3C. LC3C deletion abrogates Met entry into the autophagy-dependent degradative pathway, allowing identification of LC3C domains required for rescue. Cancer cells with low LC3C levels show enhanced Met stability, signaling, and cell invasion. These findings provide mechanistic insight into RTK recruitment to autophagosomes and establish distinct roles for ATG8 proteins in this process, supporting that differential expression of ATG8 proteins can shape the functional consequences of autophagy in cancer development and progression.
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4
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Xiong W, Tang TX, Littleton E, Karcini A, Lazar IM, Capelluto DGS. Preferential phosphatidylinositol 5-phosphate binding contributes to a destabilization of the VHS domain structure of Tom1. Sci Rep 2019; 9:10868. [PMID: 31350523 PMCID: PMC6659632 DOI: 10.1038/s41598-019-47386-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 07/16/2019] [Indexed: 12/21/2022] Open
Abstract
Tom1 transports endosomal ubiquitinated proteins that are targeted for degradation in the lysosomal pathway. Infection of eukaryotic cells by Shigella flexneri boosts oxygen consumption and promotes the synthesis of phosphatidylinositol-5-phosphate (PtdIns5P), which triggers Tom1 translocation to signaling endosomes. Removing Tom1 from its cargo trafficking function hinders protein degradation in the host and, simultaneously, enables bacterial survival. Tom1 preferentially binds PtdIns5P via its VHS domain, but the effects of a reducing environment as well as PtdIns5P on the domain structure and function are unknown. Thermal denaturation studies demonstrate that, under reducing conditions, the monomeric Tom1 VHS domain switches from a three-state to a two-state transition behavior. PtdIns5P reduced thermostability, interhelical contacts, and conformational compaction of Tom1 VHS, suggesting that the phosphoinositide destabilizes the protein domain. Destabilization of Tom1 VHS structure was also observed with other phospholipids. Isothermal calorimetry data analysis indicates that, unlike ubiquitin, Tom1 VHS endothermically binds to PtdIns5P through two noncooperative binding sites, with its acyl chains playing a relevant role in the interaction. Altogether, these findings provide mechanistic insights about the recognition of PtdIns5P by the VHS domain that may explain how Tom1, when in a different VHS domain conformational state, interacts with downstream effectors under S. flexneri infection.
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Affiliation(s)
- Wen Xiong
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute, and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Tuo-Xian Tang
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute, and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Evan Littleton
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute, and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Arba Karcini
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Iulia M Lazar
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Daniel G S Capelluto
- Protein Signaling Domains Laboratory, Department of Biological Sciences, Fralin Life Sciences Institute, and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, United States.
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5
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Zhao X, Li D, Qiu Q, Jiao B, Zhang R, Liu P, Ren R. Zfyve16 regulates the proliferation of B-lymphoid cells. Front Med 2017; 12:559-565. [PMID: 29247407 DOI: 10.1007/s11684-017-0562-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/08/2017] [Indexed: 10/18/2022]
Abstract
Zfyve16 (a.k.a. endofin or endosome-associated FYVE-domain protein), a member of the FYVE-domain protein family, is involved in endosomal trafficking and in TGF-β, BMP, and EGFR signaling. The FYVE protein SARA regulates the TGF-β signaling pathway by recruiting Smad2/3 and accelerating their phosphorylation, thereby altering their susceptibility to TGF-β-mediated T cell suppression. Zfyve16 binds to Smad4 and their binding affects the formation of Smad2/3-Smad4 complex in TGF-β signaling. However, the in vivo function of Zfyve16 remains unknown. In this study, we generated a Zfyve16 knockout mouse strain (Zfyve16KO) and examined its hematopoietic phenotypes and hematopoietic reconstruction ability. The proportion of Tcells in the peripheral blood of Zfyve16KO mice increases compared with that in wild-type mice. This finding is consistent with the role of Zfyve16 in facilitating TGF-β signaling. Unpredictably, B cell proliferation is inhibited in Zfyve16KO mice. The proliferation potential of Zfyve16KO B-lymphoid cells also significantly decreases in vitro. These results suggest that Zfyve16 inhibits the proliferation of T cells, possibly through the TGF-β signaling, but upregulates the proliferation of B-lymphoid cells.
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Affiliation(s)
- Xuemei Zhao
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Collaborative Innovation Center of System Biology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Donghe Li
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Collaborative Innovation Center of System Biology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Qingsong Qiu
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Collaborative Innovation Center of System Biology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Bo Jiao
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Collaborative Innovation Center of System Biology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Ruihong Zhang
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Collaborative Innovation Center of System Biology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Ping Liu
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Collaborative Innovation Center of System Biology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Ruibao Ren
- State Key Laboratory for Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Collaborative Innovation Center of System Biology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China. .,Department of Biology, Brandeis University, Waltham, MA, 02454, USA.
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Lobingier BT, Hüttenhain R, Eichel K, Miller KB, Ting AY, von Zastrow M, Krogan NJ. An Approach to Spatiotemporally Resolve Protein Interaction Networks in Living Cells. Cell 2017; 169:350-360.e12. [PMID: 28388416 DOI: 10.1016/j.cell.2017.03.022] [Citation(s) in RCA: 278] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 02/02/2017] [Accepted: 03/15/2017] [Indexed: 11/25/2022]
Abstract
Cells operate through protein interaction networks organized in space and time. Here, we describe an approach to resolve both dimensions simultaneously by using proximity labeling mediated by engineered ascorbic acid peroxidase (APEX). APEX has been used to capture entire organelle proteomes with high temporal resolution, but its breadth of labeling is generally thought to preclude the higher spatial resolution necessary to interrogate specific protein networks. We provide a solution to this problem by combining quantitative proteomics with a system of spatial references. As proof of principle, we apply this approach to interrogate proteins engaged by G-protein-coupled receptors as they dynamically signal and traffic in response to ligand-induced activation. The method resolves known binding partners, as well as previously unidentified network components. Validating its utility as a discovery pipeline, we establish that two of these proteins promote ubiquitin-linked receptor downregulation after prolonged activation.
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Affiliation(s)
- Braden T Lobingier
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Ruth Hüttenhain
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; Quantitative Biosciences Institute, QBI, University of California, San Francisco, San Francisco, CA 94158, USA; J. David Gladstone Institutes, San Francisco, CA 94158, USA
| | - Kelsie Eichel
- Program in Biochemistry and Molecular Biology, University of California, San Francisco, San Francisco, CA 94158, USA
| | | | - Alice Y Ting
- Departments of Genetics, Biology, and Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; Quantitative Biosciences Institute, QBI, University of California, San Francisco, San Francisco, CA 94158, USA; J. David Gladstone Institutes, San Francisco, CA 94158, USA.
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7
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Immunolocalization of Tom1 in relation to protein degradation systems in Alzheimer's disease. J Neurol Sci 2016; 365:101-7. [PMID: 27206884 DOI: 10.1016/j.jns.2016.03.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 03/18/2016] [Accepted: 03/21/2016] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disorder. Its pathological hallmarks are senile plaques (SPs), which contain extracellular deposits of amyloid β (Aβ) protein fibrils and dystrophic neurites (DNs), and neurofibrillary tangles (NFTs) containing hyperphosphorylated tau. Impairment of protein-degradation systems, including the ubiquitin-proteasome and the autophagy-lysosome systems, has been proposed as one of the causes of the accumulation of these aberrant proteins in AD brains. Tom1 (target of Myb1) was originally identified by the induction of its expression by the v-Myb oncogene and is a part of two major protein-degradation systems. The present study was conducted by immunohistochemical and immunofluorescent stainings to show that Tom1 was localized in DNs, perisomatic granules (PSGs), and NFTs in AD brains. Moreover, in DNs, Tom1 colocalized with ubiquitin, lysosomal proteins, and Tom1-related proteins (Tollip and myosin VI), which act in both protein-degradation systems via Tom1. These results indicate that Tom1 plays important roles in protein-degradation systems in AD pathogenesis.
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8
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Tom1 Modulates Binding of Tollip to Phosphatidylinositol 3-Phosphate via a Coupled Folding and Binding Mechanism. Structure 2015; 23:1910-1920. [DOI: 10.1016/j.str.2015.07.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Revised: 07/24/2015] [Accepted: 07/28/2015] [Indexed: 11/18/2022]
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9
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Dysregulated Inflammatory Signaling upon Charcot-Marie-Tooth Type 1C Mutation of SIMPLE Protein. Mol Cell Biol 2015; 35:2464-78. [PMID: 25963657 DOI: 10.1128/mcb.00300-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Endosomal trafficking is a key mechanism to modulate signal propagation and cross talk. Ubiquitin adaptors, along with endosomal sorting complex required for transport (ESCRT) complexes, are also integrated to terminate ligand-receptor activation in late endosomes and multivesicular bodies (MVBs). Within these pathways, we recently demonstrated that the protein SIMPLE is a novel player in MVB regulation. SIMPLE is also clinically important and its mutation accounts for the Charcot-Marie-Tooth type 1C (CMT1C) disease. MVB defects of mutation and deletion of SIMPLE, however, are distinct. Here, we show that MVB defects found in mutation but not deletion of SIMPLE lead to impaired turnover and accumulation of ESCRT-0 protein Hrs punctain late endosomes. We further uncover increased colocalization of ubiquitin ligase TRAF6 and Hrs in late endosomes. Upon stimulation with interkeukin-1 or transforming growth factor , prolonged activation of p38 kinase/JNK is detected, while nuclear accumulation of NF-κB and phosphorylation of SMAD2 is reduced with CMT1C mutation. The aberrant kinetics we observed in inflammatory signaling may contribute to increased tumor susceptibility and changes in the levels of chemokines/cytokines that result from CMT1C mutation. We propose that altered endosomal trafficking due to malformations of MVBs and subsequent atypical signaling kinetic may account for a toxic gain of function in CMT1C pathogenesis.
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10
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Boal F, Mansour R, Gayral M, Saland E, Chicanne G, Xuereb JM, Marcellin M, Burlet-Schiltz O, Sansonetti PJ, Payrastre B, Tronchère H. TOM1 is a PI5P effector involved in the regulation of endosomal maturation. J Cell Sci 2015; 128:815-27. [DOI: 10.1242/jcs.166314] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Phosphoinositides represent a major class of lipids specifically involved in the organisation of signaling cascades, maintenance of the identity of organelles and regulation of multiple intracellular trafficking steps. We previously described that phosphatidylinositol 5-monophosphate (PI5P), produced by the Shigella flexneri phosphatase IpgD, is implicated in the endosomal sorting of the EGFR. Here, we show that the adaptor protein TOM1 is a new PI5P direct binding partner. We identify the domain of TOM1 involved in this interaction and characterize the binding motif. Finally, we demonstrate that the recruitment of TOM1 by PI5P on signaling endosomes is responsible for the delay in EGFR degradation and fluid-phase bulk endocytosis. Taken together, our data strongly suggest that PI5P-enrichment in signaling endosomes prevents endosomal maturation through the recruitment of TOM1, and point out to a new function of PI5P in regulating discrete maturation steps in the endosomal system.
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Schuh AL, Audhya A. The ESCRT machinery: from the plasma membrane to endosomes and back again. Crit Rev Biochem Mol Biol 2014; 49:242-61. [PMID: 24456136 DOI: 10.3109/10409238.2014.881777] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The manipulation and reorganization of lipid bilayers are required for diverse cellular processes, ranging from organelle biogenesis to cytokinetic abscission, and often involves transient membrane disruption. A set of membrane-associated proteins collectively known as the endosomal sorting complex required for transport (ESCRT) machinery has been implicated in membrane scission steps, which transform a single, continuous bilayer into two distinct bilayers, while simultaneously segregating cargo throughout the process. Components of the ESCRT pathway, which include 5 distinct protein complexes and an array of accessory factors, each serve discrete functions. This review focuses on the molecular mechanisms by which the ESCRT proteins facilitate cargo sequestration and membrane remodeling and highlights their unique roles in cellular homeostasis.
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Affiliation(s)
- Amber L Schuh
- Department of Biomolecular Chemistry, University of Wisconsin-Madison School of Medicine and Public Health , Madison, WI , USA
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12
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Tumbarello DA, Kendrick-Jones J, Buss F. Myosin VI and its cargo adaptors - linking endocytosis and autophagy. J Cell Sci 2013; 126:2561-70. [PMID: 23781020 DOI: 10.1242/jcs.095554] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The coordinated trafficking and tethering of membrane cargo within cells relies on the function of distinct cytoskeletal motors that are targeted to specific subcellular compartments through interactions with protein adaptors and phospholipids. The unique actin motor myosin VI functions at distinct steps during clathrin-mediated endocytosis and the early endocytic pathway - both of which are involved in cargo trafficking and sorting - through interactions with Dab2, GIPC, Tom1 and LMTK2. This multifunctional ability of myosin VI can be attributed to its cargo-binding tail region that contains two protein-protein interaction interfaces, a ubiquitin-binding motif and a phospholipid binding domain. In addition, myosin VI has been shown to be a regulator of the autophagy pathway, because of its ability to link the endocytic and autophagic pathways through interactions with the ESCRT-0 protein Tom1 and the autophagy adaptor proteins T6BP, NDP52 and optineurin. This function has been attributed to facilitating autophagosome maturation and subsequent fusion with the lysosome. Therefore, in this Commentary, we discuss the relationship between myosin VI and the different myosin VI adaptor proteins, particularly with regards to the spatial and temporal regulation that is required for the sorting of cargo at the early endosome, and their impact on autophagy.
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Affiliation(s)
- David A Tumbarello
- Cambridge Institute for Medical Research, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK
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13
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Why do cellular proteins linked to K63-polyubiquitin chains not associate with proteasomes? EMBO J 2013; 32:552-65. [PMID: 23314748 DOI: 10.1038/emboj.2012.354] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 12/18/2012] [Indexed: 02/08/2023] Open
Abstract
Although cellular proteins conjugated to K48-linked Ub chains are targeted to proteasomes, proteins conjugated to K63-ubiquitin chains are directed to lysosomes. However, pure 26S proteasomes bind and degrade K48- and K63-ubiquitinated substrates similarly. Therefore, we investigated why K63-ubiquitinated proteins are not degraded by proteasomes. We show that mammalian cells contain soluble factors that selectively bind to K63 chains and inhibit or prevent their association with proteasomes. Using ubiquitinated proteins as affinity ligands, we found that the main cellular proteins that associate selectively with K63 chains and block their binding to proteasomes are ESCRT0 (Endosomal Sorting Complex Required for Transport) and its components, STAM and Hrs. In vivo, knockdown of ESCRT0 confirmed that it is required to block binding of K63-ubiquitinated molecules to the proteasome. In addition, the Rad23 proteins, especially hHR23B, were found to bind specifically to K48-ubiquitinated proteins and to stimulate proteasome binding. The specificities of these proteins for K48- or K63-ubiquitin chains determine whether a ubiquitinated protein is targeted for proteasomal degradation or delivered instead to the endosomal-lysosomal pathway.
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14
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Wang M, Liu S, Liu P. Gene expression profile of multiple myeloma cell line treated by arsenic trioxide. ACTA ACUST UNITED AC 2010; 27:646-9. [PMID: 18231732 DOI: 10.1007/s11596-007-0606-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Indexed: 11/30/2022]
Abstract
cDNA microarray was used to compare the gene expression profiles of multiple myeloma cell line RPMI8226 24 h before and after treatment with arsenic trioxide. Two cDNA probes were prepared by mRNA reverse transcription of both arsenic trioxide-treated and untreated RPMI8226 cells. The probes were labeled with Cy3 and Cy5 fluorescence dyes separately, hybridized with cDNA microarray representing 4096 different human genes, and scanned for fluorescence intensity. The differences in gene expression were calculated on the basis of the ratios of signal intensity of treated and untreated samples. The up-and down-regulated genes were screened through the analysis of gene expression ratios. The results showed that 273 genes were differentially altered at mRNA level, 121 genes were up-regulated and 152 were down-regulated. It is concluded that the treatment with arsenic trioxide can induce a variety of gene changes in RPMI8226 cell line. Many genes may be involved in the pathogenesis of multiple myeloma. ALK-1 and TXNIP genes may play an important role in the apoptosis and partial differentiation of RPMI8226 cells.
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Affiliation(s)
- Mengchang Wang
- Department of Hematology, the First Hospital of Xi'an Jiaotong University, Xi'an, 710061, China.
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15
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Wywial E, Singh SM. Identification and structural characterization of FYVE domain-containing proteins of Arabidopsis thaliana. BMC PLANT BIOLOGY 2010; 10:157. [PMID: 20678208 PMCID: PMC3017826 DOI: 10.1186/1471-2229-10-157] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 08/02/2010] [Indexed: 05/02/2023]
Abstract
BACKGROUND FYVE domains have emerged as membrane-targeting domains highly specific for phosphatidylinositol 3-phosphate (PtdIns(3)P). They are predominantly found in proteins involved in various trafficking pathways. Although FYVE domains may function as individual modules, dimers or in partnership with other proteins, structurally, all FYVE domains share a fold comprising two small characteristic double-stranded beta-sheets, and a C-terminal alpha-helix, which houses eight conserved Zn2+ ion-binding cysteines. To date, the structural, biochemical, and biophysical mechanisms for subcellular targeting of FYVE domains for proteins from various model organisms have been worked out but plant FYVE domains remain noticeably under-investigated. RESULTS We carried out an extensive examination of all Arabidopsis FYVE domains, including their identification, classification, molecular modeling and biophysical characterization using computational approaches. Our classification of fifteen Arabidopsis FYVE proteins at the outset reveals unique domain architectures for FYVE containing proteins, which are not paralleled in other organisms. Detailed sequence analysis and biophysical characterization of the structural models are used to predict membrane interaction mechanisms previously described for other FYVE domains and their subtle variations as well as novel mechanisms that seem to be specific to plants. CONCLUSIONS Our study contributes to the understanding of the molecular basis of FYVE-based membrane targeting in plants on a genomic scale. The results show that FYVE domain containing proteins in plants have evolved to incorporate significant differences from those in other organisms implying that they play a unique role in plant signaling pathways and/or play similar/parallel roles in signaling to other organisms but use different protein players/signaling mechanisms.
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Affiliation(s)
- Ewa Wywial
- Department of Biology, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
| | - Shaneen M Singh
- Department of Biology, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
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16
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Wang T, Liu NS, Seet LF, Hong W. The Emerging Role of VHS Domain-Containing Tom1, Tom1L1 and Tom1L2 in Membrane Trafficking. Traffic 2010; 11:1119-28. [DOI: 10.1111/j.1600-0854.2010.01098.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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17
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Liu NS, Loo LS, Loh E, Seet LF, Hong W. Participation of Tom1L1 in EGF-stimulated endocytosis of EGF receptor. EMBO J 2009; 28:3485-99. [PMID: 19798056 PMCID: PMC2756567 DOI: 10.1038/emboj.2009.282] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Accepted: 08/18/2009] [Indexed: 12/25/2022] Open
Abstract
Although many proteins have been shown to participate in ligand-stimulated endocytosis of EGF receptor (EGFR), the adaptor protein responsible for interaction of activated EGFR with endocytic machinery remains elusive. We show here that EGF stimulates transient tyrosine phosphorylation of Tom1L1 by the Src family kinases, resulting in transient interaction of Tom1L1 with the activated EGFR bridged by Grb2 and Shc. Cytosolic Tom1L1 is recruited onto the plasma membrane and subsequently redistributes into the early endosome. Mutant forms of Tom1L1 defective in Tyr-phosphorylation or interaction with Grb2 are incapable of interaction with EGFR. These mutants behave as dominant-negative mutants to inhibit endocytosis of EGFR. RNAi-mediated knockdown of Tom1L1 inhibits endocytosis of EGFR. The C-terminal tail of Tom1L1 contains a novel clathrin-interacting motif responsible for interaction with the C-terminal region of clathrin heavy chain, which is important for exogenous Tom1L1 to rescue endocytosis of EGFR in Tom1L1 knocked-down cells. These results suggest that EGF triggers a transient Grb2/Shc-mediated association of EGFR with Tyr-phosphorylated Tom1L1 to engage the endocytic machinery for endocytosis of the ligand-receptor complex.
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Affiliation(s)
- Ning Sheng Liu
- Cancer and Developmental Cell Biology Division, Institute of Molecular and Cell Biology, Singapore
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18
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Raiborg C, Stenmark H. The ESCRT machinery in endosomal sorting of ubiquitylated membrane proteins. Nature 2009; 458:445-52. [PMID: 19325624 DOI: 10.1038/nature07961] [Citation(s) in RCA: 1040] [Impact Index Per Article: 69.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Selective trafficking of membrane proteins to lysosomes for destruction is required for proper cell signalling and metabolism. Ubiquitylation aids this process by specifying which proteins should be transported to the lysosome lumen by the multivesicular endosome pathway. The endosomal sorting complex required for transport (ESCRT) machinery sorts cargo labelled with ubiquitin into invaginations of endosome membranes. Then, through a highly conserved mechanism also used in cytokinesis and viral budding, it mediates the breaking off of the cargo-containing intraluminal vesicles from the perimeter membrane. The involvement of the ESCRT machinery in suppressing diseases such as cancer, neurodegeneration and infections underscores its importance to the cell.
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Affiliation(s)
- Camilla Raiborg
- Centre for Cancer Biomedicine, Norwegian Radium Hospital, University of Oslo, Oslo, Norway
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19
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Blanc C, Charette SJ, Mattei S, Aubry L, Smith EW, Cosson P, Letourneur F. DictyosteliumTom1 Participates to an Ancestral ESCRT-0 Complex. Traffic 2009; 10:161-71. [DOI: 10.1111/j.1600-0854.2008.00855.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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20
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Girirajan S, Hauck PM, Williams S, Vlangos CN, Szomju BB, Solaymani-Kohal S, Mosier PD, White KL, McCoy K, Elsea SH. Tom1l2 hypomorphic mice exhibit increased incidence of infections and tumors and abnormal immunologic response. Mamm Genome 2008; 19:246-62. [PMID: 18343975 DOI: 10.1007/s00335-008-9100-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2007] [Accepted: 01/28/2008] [Indexed: 12/11/2022]
Abstract
Studies have shown that the TOM1 family of proteins, including TOM1 and TOM1L1, are actively involved in endosomal trafficking and function in the immune response. However, much less is known about the function of TOM1L2. To understand the biological importance of TOM1L2 and the potential significance of its cellular role, we created and evaluated Tom1l2 gene-trapped mice with reduced Tom1l2 expression. Mice hypomorphic for Tom1l2 exhibited numerous infections and tumors compared to wild-type littermates. Associated with this increased risk for infection and tumor formation, apparently healthy Tom1l2 hypomorphs also had splenomegaly, elevated B- and T-cell counts, and an impaired humoral response, although at a reduced penetrance. Furthermore, cellular localization studies showed that a Tom1l2-GFP fusion protein colocalizes with Golgi compartments, supporting the role of Tom1l2 in cellular trafficking, while molecular modeling and bioinformatic analysis of Tom1l2 illustrated a structural basis for a functional role in trafficking. These results indicate a role for Tom1l2 in the immune response and possibly in tumor suppression.
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Affiliation(s)
- Santhosh Girirajan
- Department of Human Genetics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA 23298, USA
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21
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Shi W, Chang C, Nie S, Xie S, Wan M, Cao X. Endofin acts as a Smad anchor for receptor activation in BMP signaling. J Cell Sci 2007; 120:1216-24. [PMID: 17356069 DOI: 10.1242/jcs.03400] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Signaling through receptors of the transforming growth factor beta (TGFbeta) superfamily is mediated by cytoplasmic Smad proteins. It has been demonstrated that Smad anchor for receptor activation (SARA) facilitates TGFbeta and activin/nodal signaling by recruiting and presenting Smad2/3 to the receptor complex. SARA does not bind Smad1 and hence does not enhance bone morphogenetic protein (BMP) signaling. Here we report for the first time that the endosome-associated FYVE-domain protein endofin acts as a Smad anchor for receptor activation in BMP signaling. We demonstrate that endofin binds Smad1 preferentially and enhances Smad1 phosphorylation and nuclear localization upon BMP stimulation. Silencing of endofin by RNAi resulted in a reduction in BMP-dependent Smad1 phosphorylation. Moreover, disruption of the membrane-anchoring FYVE motif by point mutation led to a reduction of BMP-responsive gene expression in cell culture and Xenopus ectodermal explants. Furthermore, we demonstrate that endofin contains a protein-phosphatase-binding motif, which functions to negatively modulate BMP signals through receptor dephosphorylation. Taken together, our results suggest that endofin plays an important role in both positive and negative feedback regulation of the BMP signaling pathway.
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Affiliation(s)
- Weibin Shi
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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22
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Chen YG, Wang Z, Ma J, Zhang L, Lu Z. Endofin, a FYVE domain protein, interacts with Smad4 and facilitates transforming growth factor-beta signaling. J Biol Chem 2007; 282:9688-9695. [PMID: 17272273 DOI: 10.1074/jbc.m611704200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transforming growth factor-beta (TGF-beta) signaling is facilitated by scaffold proteins such as SARA (Smad anchor for receptor activation). Endofin, a member of the FYVE domain protein family, has been suggested to regulate membrane trafficking. In this study, we report that endofin functions as a scaffold protein to facilitate TGF-beta signaling. Overexpression of endofin FYVE domain-deletion mutants inhibited TGF-beta-induced expression of CAGA-luciferase. Knockdown of endogenous endofin expression by RNA interference specifically led to reduction of the transcriptional responses of TGF-beta, but had no effect on BMP- or Wnt1-induced reporter expression. Furthermore, in endofin small interfering RNA-expressing stable cells, TGF-beta-mediated expression of plasminogen activator inhibitor-1 and p21(Cip1) was significantly reduced, and TGF-beta-promoted apoptosis was also impaired. We further showed that endofin could interact with Smad4 and TGF-beta type I receptors. Reduction of endogenous endofin expression resulted in a decrease of TGF-beta-induced Smad2 phosphorylation and Smad2-Smad4 complex formation. Together, our findings suggest that endofin facilitates TGF-beta signaling as a scaffold protein to promote the R-Smad-Smad4 complex formation by bringing Smad4 to the proximity of the receptor complex.
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Affiliation(s)
- Ye-Guang Chen
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China.
| | - Zhi Wang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
| | - Jing Ma
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
| | - Long Zhang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
| | - Zhongxian Lu
- Department of Medicine and Biological Chemistry, College of Medicine, University of California, Irvine, California 92697
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23
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Raiborg C, Wesche J, Malerød L, Stenmark H. Flat clathrin coats on endosomes mediate degradative protein sorting by scaffolding Hrs in dynamic microdomains. J Cell Sci 2006; 119:2414-24. [PMID: 16720641 DOI: 10.1242/jcs.02978] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Endocytosed membrane proteins that are destined for degradation in lysosomes are ubiquitylated and recognised by sorting complexes on endosome membranes. The ubiquitin-binding sorting component Hrs as well as ubiquitylated cargo are enriched in a characteristic flat clathrin coat on the endosome membrane. The function of clathrin within this coat has not been investigated. Here, we show that both clathrin and the clathrin-box motif of Hrs are required for the clustering of Hrs into restricted microdomains. The C-terminus of Hrs, which contains the clathrin-box, is sufficient to redirect a phosphatidylinositol(3)-phosphate-binding protein into the Hrs- and clathrin-containing microdomains. Although these microdomains show little lateral diffusion in the membrane, they are dynamic structures that exchange Hrs and clathrin with similar kinetics, and acquire the downstream sorting component Tsg101. The clathrin-mediated clustering is essential for the function of Hrs in degradative protein sorting. We conclude that clathrin is responsible for concentrating Hrs in endosomal microdomains specialised for recognition of ubiquitylated membrane proteins, thus enabling efficient sorting of cargo into the degradative pathway.
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Affiliation(s)
- Camilla Raiborg
- Department of Biochemistry, Institute for Cancer Research, The Norwegian Radium Hospital and The University of Oslo, Montebello, N-0310 Oslo, Norway
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24
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Costa R, Warren D, Ayscough K. Lsb5p interacts with actin regulators Sla1p and Las17p, ubiquitin and Arf3p to couple actin dynamics to membrane trafficking processes. Biochem J 2006; 387:649-58. [PMID: 15651983 PMCID: PMC1134994 DOI: 10.1042/bj20041729] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The importance of coupling the process of endocytosis to factors that regulate actin dynamics has been clearly demonstrated in yeast, and many proteins involved in these mechanisms have been identified. Sla1p is a well-characterized yeast protein that binds both to activators of actin dynamics, Las17p and Pan1p, and to cargo proteins, such as the pheromone receptor Ste2p. Previously, we reported that the Lsb5 protein plays a role in endocytosis in yeast and that it localizes to the plasma membrane. Lsb5p has a similar structure to the GGA [Golgi-localized, gamma-ear-containing, Arf (ADP-ribosylation factor)-binding] family of proteins with an N-terminal VHS [Vps27p (vacuolar protein sorting protein 27), Hrs, Stam] domain and a GAT (GGA and Tom1) domain. It does not, however, contain either a gamma-adaptin ear or a clathrin-binding motif. In the present study, we have further defined its interaction site with both Sla1p and with Las17p, two regulators of actin dynamics. The site of interaction with Sla1p involves the Sla1 HD1 (homology domain 1), which also was shown previously to interact with the pheromone receptor Ste2p. We also demonstrate hitherto unknown interactions between Lsb5p and the active form of the yeast Arf3 protein, and with ubiquitin. Finally, we demonstrate a requirement for Arf3p expression in order to localize Lsb5p to the correct cortical site in cells. Taken together, our data provide further evidence for the role of Lsb5p in membrane-trafficking events at the plasma membrane and also demonstrate for the first time an interaction of Arf3 with the endocytic machinery in yeast.
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Affiliation(s)
- Rosaria Costa
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, U.K
| | - Derek T. Warren
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, U.K
| | - Kathryn R. Ayscough
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, U.K
- To whom correspondence should be addressed (email )
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25
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Franco M, Furstoss O, Simon V, Benistant C, Hong WJ, Roche S. The adaptor protein Tom1L1 is a negative regulator of Src mitogenic signaling induced by growth factors. Mol Cell Biol 2006; 26:1932-47. [PMID: 16479011 PMCID: PMC1430241 DOI: 10.1128/mcb.26.5.1932-1947.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Src family of protein-tyrosine kinases (SFK) play important roles in mitogenesis and morphological changes induced by growth factors. The involved substrates are, however, ill defined. Using an antiphosphotyrosine antibody to screen tyrosine-phosphorylated cDNA expression library, we have identified Tom1L1, an adaptor protein of the Tom1 family and a novel substrate and activator of the SFK. Surprisingly, we found that Tom1L1 does not promote DNA synthesis induced by Src. Furthermore, we report that Tom1L1 negatively regulates SFK mitogenic signaling induced by platelet-derived growth factor (PDGF) through modulation of SFK-receptor association: (i) Tom1L1 inhibits DNA synthesis induced by PDGF; (ii) inhibition is overcome by c-myc expression or p53 inactivation, two regulators of SFK mitogenic function; (iii) Src or Fyn coexpression overrides Tom1L1 mitogenic activity; (iv) overexpression of the adaptor reduces Src association with the receptor; and (v) protein inactivation potentiates receptor complex formation, allowing increased SFK activation and DNA synthesis. However, Tom1L1 affects neither DNA synthesis induced by the constitutively active allele SrcY527F nor SFK-regulated actin assembly induced by PDGF. Finally, overexpressed Tom1 and Tom1L2 also associate with Src and affected mitogenic signaling in agreement with some redundancy among members of the Tom1 family. We concluded that Tom1L1 defines a novel mechanism for regulation of SFK mitogenic signaling induced by growth factors.
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Affiliation(s)
- Mélanie Franco
- CRBM, CNRS FRE2593, 1919 Route de Mende, 34293 Montpellier Cedex 05, France.
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26
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Wang MC. Changes of gene expression profile of multiple myeloma cell line RPMI 8226 treated by arsenic trioxide. ACTA ACUST UNITED AC 2006. [DOI: 10.3736/jcim20060211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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27
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Katoh Y, Imakagura H, Futatsumori M, Nakayama K. Recruitment of clathrin onto endosomes by the Tom1–Tollip complex. Biochem Biophys Res Commun 2006; 341:143-9. [PMID: 16412388 DOI: 10.1016/j.bbrc.2005.12.156] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Accepted: 12/23/2005] [Indexed: 11/17/2022]
Abstract
Tom1 (target of Myb 1) and its related proteins (Tom1L1/Srcasm and Tom1L2) constitute a protein family and share an N-terminal VHS (Vps27p/Hrs/Stam) domain and a following GAT (GGA and Tom1) domain, both of which are also conserved in the GGA family proteins. However, the C-terminal half is not significantly conserved between the Tom1 and GGA families or even between Tom1 and Tom1L1. We have previously shown that the GAT domain of Tom1 interacts with Tollip (Toll-interacting protein), which is associated with endosomes, to which it recruits Tom1. We here extend the previous data and show that the GAT domains of Tom1L1 and Tom1L2 also interact with Tollip, and the C-terminal regions of all the Tom1 family proteins interact with clathrin. Furthermore, when coexpressed with Tollip, all the Tom1 family proteins recruite clathrin onto endosomes. These results indicate that, in conjunction with Tollip, Tom1 family proteins play an important role in recruiting clathrin onto endosomes and suggest that they modulate endosomal functions.
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Affiliation(s)
- Yohei Katoh
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan
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28
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Abstract
TOM1 and its related proteins, TOM1-like1 (TOM1-L1) and TOM1-like2 (TOM1-L2), constitute a subfamily of the VHS domain protein family. We have recently shown that endofin, a FYVE domain protein associated with the early endosome, is able to recruit cytosolic TOM1 onto endosomal membranes. To reveal the biological consequence of endofin-mediated endosomal recruitment of TOM1, we have identified the clathrin heavy chain as a major interacting protein for TOM1. Optimal clathrin binding by TOM1 involves three sites: residues 300-321, 321-326 and a putative clathrin-binding box at residues 362-366 (362LEDEF366). Although residues 321-326 could function independently as a weak clathrin-binding motif, deletion of amino acids 300-321 or mutation of 362Leu and 364Asp to Ala residues reduced the binding of clathrin to TOM1. A fragment lacking amino acids 300-322 and containing 362Leu and 364Asp to Ala mutations lost the ability to interact with clathrin. Remarkably, overexpression of endofin led to a massive and specific recruitment of clathrin [but not dynamin, or the adaptor protein (AP) complexes, AP1, AP2 or AP3] onto endofin-positive endosomes. Although SARA is homologous to endofin, it did not interact with the C-terminal region of TOM1. Examination of chimeric proteins of endofin and SARA suggests that the C-terminal half of endofin is responsible for interaction with the C-terminal region of TOM1 and for recruitment of TOM1 and clathrin to endosomes. The correlation between the ability of endofin to interact with the C-terminal domain of TOM1 and clathrin recruitment suggests that endofin may recruit clathrin via TOM1. Indeed, a chimeric protein consisting of TOM1 fused to two FYVE domains derived from endofin has the ability to recruit clathrin onto endosomal structures. Moreover, we show that affinity-purified TOM1 antibody can abolish binding of clathrin to the C-terminal region of TOM1. Upon microinjection into cells, this antibody reduced the membrane association of clathrin. These results, taken together, suggest that TOM1 is an important molecule for membrane recruitment of clathrin, and that endofin is able to exploit this recruitment at the endosome.
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Affiliation(s)
- Li-Fong Seet
- Membrane Biology Laboratory, Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673, Republic of Singapore
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Mattera R, Puertollano R, Smith WJ, Bonifacino JS. The trihelical bundle subdomain of the GGA proteins interacts with multiple partners through overlapping but distinct sites. J Biol Chem 2004; 279:31409-18. [PMID: 15143060 DOI: 10.1074/jbc.m402183200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Golgi-localized, gamma-adaptin ear-containing, ARF-binding (GGA) proteins are monomeric clathrin adaptors that mediate the sorting of cargo at the trans-Golgi network and endosomes. The GGAs contain four different domains named Vps27, Hrs, Stam (VHS); GGAs and TOM1 (GAT); hinge; and gamma-adaptin ear (GAE). The VHS domain recognizes transmembrane cargo, whereas the hinge and GAE regions bind clathrin and accessory proteins, respectively. The GAT domain is a polyfunctional module that interacts with various partners including the small GTPase ARF, the endosomal fusion regulator Rabaptin-5, ubiquitin, and the product of the tumor susceptibility gene 101 (TSG101). Previous x-ray crystallographic analyses showed that the GAT region is composed of two subdomains, an N-terminal helix-loop-helix containing the ARF binding site, and a C-terminal triple alpha-helical (trihelical) bundle. In this study, we define the Rabaptin-5 binding site on the GGA1-GAT domain and its relationship to the binding sites for ubiquitin and TSG101. Our observations show that Rabaptin-5, ubiquitin, and TSG101 bind to overlapping but distinct binding sites on the trihelical bundle. The different GAT binding partners engage in both competitive and cooperative interactions that may be important for the function of the GGAs in protein sorting.
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Affiliation(s)
- Rafael Mattera
- Cell Biology and Metabolism Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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30
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Katoh Y, Shiba Y, Mitsuhashi H, Yanagida Y, Takatsu H, Nakayama K. Tollip and Tom1 form a complex and recruit ubiquitin-conjugated proteins onto early endosomes. J Biol Chem 2004; 279:24435-43. [PMID: 15047686 DOI: 10.1074/jbc.m400059200] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tom1 (target of Myb1) is a protein of unknown function. Tom1 and its relative Tom1L1 have an N-terminal VHS (Vps27p/Hrs/Stam) domain followed by a GAT (GGA and Tom1) domain, both of which are also found in the GGA (Golgi-localizing, gamma-adaptin ear domain homology, ADP-ribosylation factor-binding protein) family of proteins. Although the VHS and GAT domains of GGA proteins bind to transmembrane cargo proteins and the small GTPase ADP-ribosylation factor, respectively, the VHS and GAT domains of Tom1 are unable to interact with these proteins. In this study, we show that the GAT domains of Tom1 and Tom1L1 interact with ubiquitin and Tollip (Toll-interacting protein). Ubiquitin bound the GAT domains of Tom1, Tom1L1, and GGA proteins, whereas Tollip interacted specifically with Tom1 and Tom1L1. Ubiquitin and Tollip bound to an overlapping region of the Tom1-GAT domain in a mutually exclusive manner. Tom1 was predominantly cytosolic when expressed in cells. On the other hand, Tollip was localized on early endosomes and recruited Tom1 and ubiquitinated proteins. These observations suggest that Tollip and Tom1 form a complex and regulate endosomal trafficking of ubiquitinated proteins.
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Affiliation(s)
- Yohei Katoh
- Institute of Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
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