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Gan S, Zhou S, Ma J, Xiong M, Xiong W, Fan X, Liu K, Gui Y, Chen B, Zhang B, Wang X, Wang F, Li Z, Yan W, Ma M, Yuan S. BAG5 regulates HSPA8-mediated protein folding required for sperm head-tail coupling apparatus assembly. EMBO Rep 2024; 25:2045-2070. [PMID: 38454159 PMCID: PMC11015022 DOI: 10.1038/s44319-024-00112-x] [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: 08/07/2023] [Revised: 02/01/2024] [Accepted: 02/22/2024] [Indexed: 03/09/2024] Open
Abstract
Teratozoospermia is a significant cause of male infertility, but the pathogenic mechanism of acephalic spermatozoa syndrome (ASS), one of the most severe teratozoospermia, remains elusive. We previously reported Spermatogenesis Associated 6 (SPATA6) as the component of the sperm head-tail coupling apparatus (HTCA) required for normal assembly of the sperm head-tail conjunction, but the underlying molecular mechanism has not been explored. Here, we find that the co-chaperone protein BAG5, expressed in step 9-16 spermatids, is essential for sperm HTCA assembly. BAG5-deficient male mice show abnormal assembly of HTCA, leading to ASS and male infertility, phenocopying SPATA6-deficient mice. In vivo and in vitro experiments demonstrate that SPATA6, cargo transport-related myosin proteins (MYO5A and MYL6) and dynein proteins (DYNLT1, DCTN1, and DNAL1) are misfolded upon BAG5 depletion. Mechanistically, we find that BAG5 forms a complex with HSPA8 and promotes the folding of SPATA6 by enhancing HSPA8's affinity for substrate proteins. Collectively, our findings reveal a novel protein-regulated network in sperm formation in which BAG5 governs the assembly of the HTCA by activating the protein-folding function of HSPA8.
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Affiliation(s)
- Shiming Gan
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Shumin Zhou
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Department of Urology & Andrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310016, China
| | - Jinzhe Ma
- Department of Histology and Embryology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Mengneng Xiong
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Reproductive Medicine Center, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Wenjing Xiong
- Laboratory of Animal Center, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Xu Fan
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Kuan Liu
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yiqian Gui
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Bei Chen
- Reproductive Medicine Center, Renmin Hospital of Wuhan University, Wuhan, 430060, China
| | - Beibei Zhang
- Department of Urology & Andrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310016, China
| | - Xiaoli Wang
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Fengli Wang
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Zhean Li
- Department of Urology & Andrology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310016, China
| | - Wei Yan
- The Lundquist Institute for Biomedical Innovation at Harbor-UCLA, Torrance, CA, 90502, USA
| | - Meisheng Ma
- Department of Histology and Embryology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Cell Architecture Research Center, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Shuiqiao Yuan
- Institute of Reproductive Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
- Laboratory of Animal Center, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Rivera M, Burgos‐Bravo F, Engelberger F, Asor R, Lagos‐Espinoza MIA, Figueroa M, Kukura P, Ramírez‐Sarmiento CA, Baez M, Smith SB, Wilson CAM. Effect of temperature and nucleotide on the binding of BiP chaperone to a protein substrate. Protein Sci 2023; 32:e4706. [PMID: 37323096 PMCID: PMC10303699 DOI: 10.1002/pro.4706] [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: 12/18/2022] [Revised: 06/01/2023] [Accepted: 06/12/2023] [Indexed: 06/17/2023]
Abstract
BiP (immunoglobulin heavy-chain binding protein) is a Hsp70 monomeric ATPase motor that plays broad and crucial roles in maintaining proteostasis inside the cell. Structurally, BiP is formed by two domains, a nucleotide-binding domain (NBD) with ATPase activity connected by a flexible hydrophobic linker to the substrate-binding domain. While the ATPase and substrate binding activities of BiP are allosterically coupled, the latter is also dependent on nucleotide binding. Recent structural studies have provided new insights into BiP's allostery; however, the influence of temperature on the coupling between substrate and nucleotide binding to BiP remains unexplored. Here, we study BiP's binding to its substrate at the single molecule level using thermo-regulated optical tweezers which allows us to mechanically unfold the client protein and explore the effect of temperature and different nucleotides on BiP binding. Our results confirm that the affinity of BiP for its protein substrate relies on nucleotide binding, by mainly regulating the binding kinetics between BiP and its substrate. Interestingly, our findings also showed that the apparent affinity of BiP for its protein substrate in the presence of nucleotides remains invariable over a wide range of temperatures, suggesting that BiP may interact with its client proteins with similar affinities even when the temperature is not optimal. Thus, BiP could play a role as a "thermal buffer" in proteostasis.
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Affiliation(s)
- Maira Rivera
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological SciencesPontificia Universidad Católica de ChileSantiagoChile
- ANID–Millennium Science Initiative Program–Millennium Institute for Integrative Biology (iBio)SantiagoChile
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y FarmacéuticasUniversidad de ChileSantiagoChile
| | - Francesca Burgos‐Bravo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y FarmacéuticasUniversidad de ChileSantiagoChile
- Institute for Quantitative BiosciencesUniversity of CaliforniaBerkeleyCaliforniaUSA
| | - Felipe Engelberger
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological SciencesPontificia Universidad Católica de ChileSantiagoChile
- ANID–Millennium Science Initiative Program–Millennium Institute for Integrative Biology (iBio)SantiagoChile
| | - Roi Asor
- Physical and Theoretical Chemistry Laboratory, Department of ChemistryUniversity of OxfordOxfordUK
- The Kavli Institute for Nanoscience DiscoveryOxfordUK
| | - Miguel I. A. Lagos‐Espinoza
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y FarmacéuticasUniversidad de ChileSantiagoChile
| | - Maximiliano Figueroa
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias BiológicasUniversidad de ConcepciónConcepciónChile
| | - Philipp Kukura
- Physical and Theoretical Chemistry Laboratory, Department of ChemistryUniversity of OxfordOxfordUK
- The Kavli Institute for Nanoscience DiscoveryOxfordUK
| | - César A. Ramírez‐Sarmiento
- Institute for Biological and Medical Engineering, Schools of Engineering, Medicine and Biological SciencesPontificia Universidad Católica de ChileSantiagoChile
- ANID–Millennium Science Initiative Program–Millennium Institute for Integrative Biology (iBio)SantiagoChile
| | - Mauricio Baez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y FarmacéuticasUniversidad de ChileSantiagoChile
| | | | - Christian A. M. Wilson
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y FarmacéuticasUniversidad de ChileSantiagoChile
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Trcka F, Durech M, Vankova P, Chmelik J, Martinkova V, Hausner J, Kadek A, Marcoux J, Klumpler T, Vojtesek B, Muller P, Man P. Human Stress-inducible Hsp70 Has a High Propensity to Form ATP-dependent Antiparallel Dimers That Are Differentially Regulated by Cochaperone Binding. Mol Cell Proteomics 2019; 18:320-337. [PMID: 30459217 PMCID: PMC6356074 DOI: 10.1074/mcp.ra118.001044] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/09/2018] [Indexed: 12/23/2022] Open
Abstract
Eukaryotic protein homeostasis (proteostasis) is largely dependent on the action of highly conserved Hsp70 molecular chaperones. Recent evidence indicates that, apart from conserved molecular allostery, Hsp70 proteins have retained and adapted the ability to assemble as functionally relevant ATP-bound dimers throughout evolution. Here, we have compared the ATP-dependent dimerization of DnaK, human stress-inducible Hsp70, Hsc70 and BiP Hsp70 proteins, showing that their dimerization propensities differ, with stress-inducible Hsp70 being predominantly dimeric in the presence of ATP. Structural analyses using hydrogen/deuterium exchange mass spectrometry, native electrospray ionization mass spectrometry and small-angle X-ray scattering revealed that stress-inducible Hsp70 assembles in solution as an antiparallel dimer with the intermolecular interface closely resembling the ATP-bound dimer interfaces captured in DnaK and BiP crystal structures. ATP-dependent dimerization of stress-inducible Hsp70 is necessary for its efficient interaction with Hsp40, as shown by experiments with dimerization-deficient mutants. Moreover, dimerization of ATP-bound Hsp70 is required for its participation in high molecular weight protein complexes detected ex vivo, supporting its functional role in vivo As human cytosolic Hsp70 can interact with tetratricopeptide repeat (TPR) domain containing cochaperones, we tested the interaction of Hsp70 ATP-dependent dimers with Chip and Tomm34 cochaperones. Although Chip associates with intact Hsp70 dimers to form a larger complex, binding of Tomm34 disrupts the Hsp70 dimer and this event plays an important role in Hsp70 activity regulation. In summary, this study provides structural evidence of robust ATP-dependent antiparallel dimerization of human inducible Hsp70 protein and suggests a novel role of TPR domain cochaperones in multichaperone complexes involving Hsp70 ATP-bound dimers.
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Affiliation(s)
- Filip Trcka
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Michal Durech
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Pavla Vankova
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Josef Chmelik
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Veronika Martinkova
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Jiri Hausner
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Alan Kadek
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic
| | - Julien Marcoux
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Tomas Klumpler
- CEITEC-Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Borivoj Vojtesek
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic
| | - Petr Muller
- Regional Centre for Applied Molecular Oncology, Masaryk Memorial Cancer Institute, Zluty kopec 7, 656 53 Brno, Czech Republic;.
| | - Petr Man
- BioCeV - Institute of Microbiology of the Czech Academy of Sciences, v.v.i., Prumyslova 595, 252 50 Vestec, Czech Republic;; Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43 Prague, Czech Republic;.
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O'Donnell JP, Marsh HM, Sondermann H, Sevier CS. Disrupted Hydrogen-Bond Network and Impaired ATPase Activity in an Hsc70 Cysteine Mutant. Biochemistry 2018; 57:1073-1086. [PMID: 29300467 DOI: 10.1021/acs.biochem.7b01005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The ATPase domain of members of the 70 kDa heat shock protein (Hsp70) family shows a high degree of sequence, structural, and functional homology across species. A broadly conserved residue within the Hsp70 ATPase domain that captured our attention is an unpaired cysteine, positioned proximal to the site of nucleotide binding. Prior studies of several Hsp70 family members show this cysteine is not required for Hsp70 ATPase activity, yet select amino acid replacements of the cysteine can dramatically alter ATP hydrolysis. Moreover, post-translational modification of the cysteine has been reported to limit ATP hydrolysis for several Hsp70s. To better understand the underlying mechanism for how perturbation of this noncatalytic residue modulates Hsp70 function, we determined the structure for a cysteine-to-tryptophan mutation in the constitutively expressed, mammalian Hsp70 family member Hsc70. Our work reveals that the steric hindrance produced by a cysteine-to-tryptophan mutation disrupts the hydrogen-bond network within the active site, resulting in a loss of proper catalytic magnesium coordination. We propose that a similarly altered active site is likely observed upon post-translational oxidation. We speculate that the subtle changes we detect in the hydrogen-bonding network may relate to the previously reported observation that cysteine oxidation can influence Hsp70 interdomain communication.
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Affiliation(s)
- John P O'Donnell
- Department of Molecular Medicine, Cornell University , Ithaca, New York 14853, United States
| | - Heather M Marsh
- Department of Molecular Medicine, Cornell University , Ithaca, New York 14853, United States
| | - Holger Sondermann
- Department of Molecular Medicine, Cornell University , Ithaca, New York 14853, United States
| | - Carolyn S Sevier
- Department of Molecular Medicine, Cornell University , Ithaca, New York 14853, United States
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McCallister C, Kdeiss B, Nikolaidis N. Biochemical characterization of the interaction between HspA1A and phospholipids. Cell Stress Chaperones 2016; 21:41-53. [PMID: 26342809 PMCID: PMC4679732 DOI: 10.1007/s12192-015-0636-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 08/25/2015] [Accepted: 08/31/2015] [Indexed: 01/15/2023] Open
Abstract
Seventy-kilodalton heat shock proteins (Hsp70s) are molecular chaperones essential for maintaining cellular homeostasis. Apart from their indispensable roles in protein homeostasis, specific Hsp70s localize at the plasma membrane and bind to specific lipids. The interaction of Hsp70s with lipids has direct physiological outcomes including lysosomal rescue, microautophagy, and promotion of cell apoptosis. Despite these essential functions, the Hsp70-lipid interactions remain largely uncharacterized. In this study, we characterized the interaction of HspA1A, an inducible Hsp70, with five phospholipids. We first used high concentrations of potassium and established that HspA1A embeds in membranes when bound to all anionic lipids tested. Furthermore, we found that protein insertion is enhanced by increasing the saturation level of the lipids. Next, we determined that the nucleotide-binding domain (NBD) of the protein binds to lipids quantitatively more than the substrate-binding domain (SBD). However, for all lipids tested, the full-length protein is necessary for embedding. We also used calcium and reaction buffers equilibrated at different pH values and determined that electrostatic interactions alone may not fully explain the association of HspA1A with lipids. We then determined that lipid binding is inhibited by nucleotide-binding, but it is unaffected by protein-substrate binding. These results suggest that the HspA1A lipid-association is specific, depends on the physicochemical properties of the lipid, and is mediated by multiple molecular forces. These mechanistic details of the Hsp70-lipid interactions establish a framework of possible physiological functions as they relate to chaperone regulation and localization.
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Affiliation(s)
- Chelsea McCallister
- Department of Biological Science, Center for Applied Biotechnology Studies, and Center for Computational and Applied Mathematics, California State University, Fullerton, Fullerton, CA, 92834, USA
| | - Brianna Kdeiss
- Department of Biological Science, Center for Applied Biotechnology Studies, and Center for Computational and Applied Mathematics, California State University, Fullerton, Fullerton, CA, 92834, USA
| | - Nikolas Nikolaidis
- Department of Biological Science, Center for Applied Biotechnology Studies, and Center for Computational and Applied Mathematics, California State University, Fullerton, Fullerton, CA, 92834, USA.
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Chan SF, He JG, Chu KH, Sun CB. The Shrimp Heat Shock Cognate 70 Functions as a Negative Regulator in Vitellogenin Gene Expression1. Biol Reprod 2014; 91:14. [DOI: 10.1095/biolreprod.113.117200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Pérez-Vargas J, Romero P, López S, Arias CF. The peptide-binding and ATPase domains of recombinant hsc70 are required to interact with rotavirus and reduce its infectivity. J Virol 2006; 80:3322-31. [PMID: 16537599 PMCID: PMC1440403 DOI: 10.1128/jvi.80.7.3322-3331.2006] [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] [Indexed: 12/14/2022] Open
Abstract
The heat shock cognate protein hsc70 has been implicated as a postattachment cell receptor for rotaviruses. Here we show that hsc70 interacts specifically with rotaviruses through its peptide-binding domain, since a recombinant full-length hsc70 protein and its peptide-binding domain, but not its ATPase domain, bound triple-layered particles in a solid-phase assay, and known ligands of hsc70 competed this binding. The peptide ligands of hsc70 were also shown to block rotavirus infectivity when added to cells before virus infection, suggesting that hsc70 on the surface of MA104 cells also interacts with the virus through its peptide-binding domain and that this interaction is important for virus entry. When purified infectious virus was incubated with soluble hsc70 in the presence of the cochaperone hsp40 and ATP and then pelleted through a sucrose cushion, the recovered virus had lost 60% of its infectivity, even though hsc70 was not detected in the pellet fraction. The hsc70-treated virus showed slightly different reactivities with monoclonal antibodies and was more susceptible to heat and basic pHs than the untreated virus, suggesting that hsc70 induces a subtle conformational change in the virus that results in a reduction of its infectivity. The relevance of the ATPase activity of hsc70 for reducing virus infectivity was demonstrated by the finding that in the presence of a nonhydrolyzable analogue of ATP, virus infectivity was not affected, and a mutant protein lacking ATPase activity failed to reduce virus infection. Altogether, these results suggest that during cell infection, the interaction of the virus with hsc70 on the surface of MA104 cells results in a conformational change of virus particles that facilitates their entry into the cell cytoplasm.
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Affiliation(s)
- Jimena Pérez-Vargas
- Departamento de Génetica del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, UNAM, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos 62210, Mexico
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Newmyer SL, Schmid SL. Dominant-interfering Hsc70 mutants disrupt multiple stages of the clathrin-coated vesicle cycle in vivo. J Cell Biol 2001; 152:607-20. [PMID: 11157986 PMCID: PMC2196005 DOI: 10.1083/jcb.152.3.607] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Within the clathrin-coated vesicle (CCV) cycle, coat assembly drives the internalization of receptors from the cell surface and disassembly allows for the processing of internalized ligands. The heat shock cognate protein, hsc70, has been implicated in regulating coat disassembly. We find that in cells overexpressing ATPase-deficient hsc70 mutants, uncoating of CCVs is inhibited in vivo, and the majority of unassembled cytosolic clathrin shifts to an assembled pool that cofractionates with AP1 and AP2. Surprisingly, this assembled pool of coat proteins accumulates in the absence of cargo receptors, suggesting that disruption of hsc70 activity may cause misassembly of empty clathrin cages. The strongest effect of overexpression of hsc70 mutants is a block in transferrin receptor (TfnR) recycling, which cannot be accounted for by the degree of inhibition of uncoating of endocytic CCVs. These results suggest that hsc70 participates in multiple transport and/or sorting events between endosomal compartments. Additionally, the mutant-expressing cells are defective at internalizing transferrin. In the most potent case, the initial rate of uptake is inhibited 10-fold, and TfnR levels double at the cell surface. Our findings demonstrate that hsc70 indeed regulates coat disassembly and also suggest that this chaperone broadly modulates clathrin dynamics throughout the CCV cycle.
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Affiliation(s)
- Sherri L. Newmyer
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037
| | - Sandra L. Schmid
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037
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Perry DG, Daugherty GL, Martin WJ. Clathrin-Coated Pit-Associated Proteins Are Required for Alveolar Macrophage Phagocytosis. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.1.380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
During phagocytosis, phagocytic receptors and membrane material must be inserted in the pseudopod membrane as it extends over the phagocytic target. This may require a clathrin-mediated recycling mechanism similar to that postulated for leading edge formation during cell migration. To investigate this possibility, liposomes were used to deliver to intact rat alveolar macrophages (AMs): 1) Abs to clathrin, clathrin adaptor AP-2, and hsc70, and 2) amantadine. Phagocytosis was assayed by fluorometric and colorimetric techniques. Liposome-delivered Abs to clathrin and AP-2 inhibited AM phagocytosis of zymosan-coated, fluorescent liposomes from 16.3 ± 0.3 to 5.8 ± 0.3, and 10.1 ± 0.9 to 4.8 ± 0.2 liposomes/cell (p < 0.01). Similarly, liposome-delivered Ab to clathrin also inhibited AM phagocytosis of IgG-opsonized RBCs from 11.7 ± 1.7 to 3.8 ± 0.7 RBCs/cell (p < 0.01). Amantadine, which blocks the budding of clathrin-coated vesicles, inhibited phagocytosis from 13.8 ± 0.8 to 5.7 ± 0.6 (p < 0.01). Ab blockade of hsc70, which catalyzes clathrin turnover, also inhibited phagocytosis from 9.1 ± 0.5 to 4.3 ± 0.2 (p < 0.01). These findings suggest that clathrin-mediated receptor/membrane recycling is required for phagocytosis.
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Affiliation(s)
- Douglas G. Perry
- Division of Pulmonary and Critical Care Medicine, Indiana University School of Medicine, Indianapolis, IN 46202
| | - Gena L. Daugherty
- Division of Pulmonary and Critical Care Medicine, Indiana University School of Medicine, Indianapolis, IN 46202
| | - William J. Martin
- Division of Pulmonary and Critical Care Medicine, Indiana University School of Medicine, Indianapolis, IN 46202
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Hannan LA, Newmyer SL, Schmid SL. ATP- and cytosol-dependent release of adaptor proteins from clathrin-coated vesicles: A dual role for Hsc70. Mol Biol Cell 1998; 9:2217-29. [PMID: 9693377 PMCID: PMC25474 DOI: 10.1091/mbc.9.8.2217] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/1998] [Accepted: 06/04/1998] [Indexed: 11/11/2022] Open
Abstract
Clathrin-coated vesicles (CCV) mediate protein sorting and vesicular trafficking from the plasma membrane and the trans-Golgi network. Before delivery of the vesicle contents to the target organelles, the coat components, clathrin and adaptor protein complexes (APs), must be released. Previous work has established that hsc70/the uncoating ATPase mediates clathrin release in vitro without the release of APs. AP release has not been reconstituted in vitro, and nothing is known about the requirements for this reaction. We report a novel quantitative assay for the ATP- and cytosol- dependent release of APs from CCV. As expected, hsc70 is not sufficient for AP release; however, immunodepletion and reconstitution experiments establish that it is necessary. Interestingly, complete clathrin release is not a prerequisite for AP release, suggesting that hsc70 plays a dual role in recycling the constituents of the clathrin coat. This assay provides a functional basis for identification of the additional cytosolic factor(s) required for AP release.
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Affiliation(s)
- L A Hannan
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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