1
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Georgiev SV, Rizzoli SO. The long-loop recycling (LLR) of synaptic components as a question of economics. Mol Cell Neurosci 2023; 126:103862. [PMID: 37236414 DOI: 10.1016/j.mcn.2023.103862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/15/2023] [Accepted: 05/19/2023] [Indexed: 05/28/2023] Open
Abstract
The pre- and post-synaptic compartments contain a variety of molecules that are known to recycle between the plasma membrane and intracellular organelles. The recycling steps have been amply described in functional terms, with, for example, synaptic vesicle recycling being essential for neurotransmitter release, and postsynaptic receptor recycling being a fundamental feature of synaptic plasticity. However, synaptic protein recycling may also serve a more prosaic role, simply ensuring the repeated use of specific components, thereby minimizing the energy expenditure on the synthesis of synaptic proteins. This type of process has been recently described for components of the extracellular matrix, which undergo long-loop recycling (LLR), to and from the cell body. Here we suggest that the energy-saving recycling of synaptic components may be more widespread than is generally acknowledged, potentially playing a role in both synaptic vesicle protein usage and postsynaptic receptor metabolism.
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Affiliation(s)
- Svilen Veselinov Georgiev
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; International Max Planck Research School for Neuroscience, Göttingen, Germany.
| | - Silvio O Rizzoli
- University Medical Center Göttingen, Institute for Neuro- and Sensory Physiology, Germany; Biostructural Imaging of Neurodegeneration (BIN) Center, Göttingen, Germany; Excellence Cluster Multiscale Bioimaging, Göttingen, Germany.
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2
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Stachowiak JC, Kirchhausen T. The beauty of simplicity in membrane biology. Nat Cell Biol 2022; 24:1682-1685. [PMID: 36266490 PMCID: PMC9742310 DOI: 10.1038/s41556-022-01015-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
For the past 40 years, minimal reconstituted systems have helped cell biologists to understand the mechanisms that underlie membrane traffic. Having progressed from minimal synthetic and cell-derived ensembles to direct comparison with living systems, reconstitution is poised for ever more precise and informative understanding of membrane biology.
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Affiliation(s)
- Jeanne C. Stachowiak
- University of Texas at Austin, Department of Biomedical Engineering, Austin, TX, USA,
| | - Tomas Kirchhausen
- Harvard Medical School, Department of Cell Biology, Boston, MA, USA,Harvard Medical School, Department of Pediatrics, Boston, MA, USA
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3
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Nordquist EB, Clerico EM, Chen J, Gierasch LM. Computationally-Aided Modeling of Hsp70-Client Interactions: Past, Present, and Future. J Phys Chem B 2022; 126:6780-6791. [PMID: 36040440 PMCID: PMC10309085 DOI: 10.1021/acs.jpcb.2c03806] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hsp70 molecular chaperones play central roles in maintaining a healthy cellular proteome. Hsp70s function by binding to short peptide sequences in incompletely folded client proteins, thus preventing them from misfolding and/or aggregating, and in many cases holding them in a state that is competent for subsequent processes like translocation across membranes. There is considerable interest in predicting the sites where Hsp70s may bind their clients, as the ability to do so sheds light on the cellular functions of the chaperone. In addition, the capacity of the Hsp70 chaperone family to bind to a broad array of clients and to identify accessible sequences that enable discrimination of those that are folded from those that are not fully folded, which is essential to their cellular roles, is a fascinating puzzle in molecular recognition. In this article we discuss efforts to harness computational modeling with input from experimental data to develop a predictive understanding of the promiscuous yet selective binding of Hsp70 molecular chaperones to accessible sequences within their client proteins. We trace how an increasing understanding of the complexities of Hsp70-client interactions has led computational modeling to new underlying assumptions and design features. We describe the trend from purely data-driven analysis toward increased reliance on physics-based modeling that deeply integrates structural information and sequence-based functional data with physics-based binding energies. Notably, new experimental insights are adding to our understanding of the molecular origins of "selective promiscuity" in substrate binding by Hsp70 chaperones and challenging the underlying assumptions and design used in earlier predictive models. Taking the new experimental findings together with exciting progress in computational modeling of protein structures leads us to foresee a bright future for a predictive understanding of selective-yet-promiscuous binding exploited by Hsp70 molecular chaperones; the resulting new insights will also apply to substrate binding by other chaperones and by signaling proteins.
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Affiliation(s)
- Erik B. Nordquist
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts, 01003, United States
| | - Eugenia M. Clerico
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts, 01003, United States
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts, 01003, United States
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts, 01003, United States
| | - Lila M. Gierasch
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts, 01003, United States
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts, 01003, United States
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4
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Barber CN, Goldschmidt HL, Ma Q, Devine LR, Cole RN, Huganir RL, Raben DM. Identification of Synaptic DGKθ Interactors That Stimulate DGKθ Activity. Front Synaptic Neurosci 2022; 14:855673. [PMID: 35573662 PMCID: PMC9095502 DOI: 10.3389/fnsyn.2022.855673] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 03/16/2022] [Indexed: 01/16/2023] Open
Abstract
Lipids and their metabolic enzymes are a critical point of regulation for the membrane curvature required to induce membrane fusion during synaptic vesicle recycling. One such enzyme is diacylglycerol kinase θ (DGKθ), which produces phosphatidic acid (PtdOH) that generates negative membrane curvature. Synapses lacking DGKθ have significantly slower rates of endocytosis, implicating DGKθ as an endocytic regulator. Importantly, DGKθ kinase activity is required for this function. However, protein regulators of DGKθ's kinase activity in neurons have never been identified. In this study, we employed APEX2 proximity labeling and mass spectrometry to identify endogenous interactors of DGKθ in neurons and assayed their ability to modulate its kinase activity. Seven endogenous DGKθ interactors were identified and notably, synaptotagmin-1 (Syt1) increased DGKθ kinase activity 10-fold. This study is the first to validate endogenous DGKθ interactors at the mammalian synapse and suggests a coordinated role between DGKθ-produced PtdOH and Syt1 in synaptic vesicle recycling.
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Affiliation(s)
- Casey N. Barber
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Hana L. Goldschmidt
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Qianqian Ma
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Lauren R. Devine
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Robert N. Cole
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Richard L. Huganir
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Daniel M. Raben
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, United States,*Correspondence: Daniel M. Raben,
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5
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Jin Y, Yu G, Yuwen T, Gao D, Wang G, Zhou Y, Jiang B, Zhang X, Li C, He L, Liu M. Molecular Insight into the Extracellular Chaperone Serum Albumin in Modifying the Folding Free Energy Landscape of Client Proteins. J Phys Chem Lett 2022; 13:2711-2717. [PMID: 35311276 DOI: 10.1021/acs.jpclett.2c00265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Serum albumin (SA) is the most abundant extracellular chaperone protein presenting in various bodily fluids. Recently, several studies have revealed molecular mechanisms of SA in preventing the amyloid formation of amyloidogenic proteins. However, our insight into the mechanism SA employed to sense and regulate the folding states of full-length native proteins is still limited. Addressing this question is technically challenging due to the intrinsic dynamic nature of both chaperones and clients. Here using nuclear magnetic resonance spectroscopy, we show SA modifies the folding free energy landscape of clients and subsequently alters the equilibria between different compact conformations of its clients, resulting in the increased populations of excited states of client proteins. This modulation of client protein conformation by SA can change the client protein activity in a way that cannot be interpreted on the basis of its ground state structure; therefore, our work provides an alternative insight of SA in retaining a balanced functional proteome.
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Affiliation(s)
- Yangzhuoyue Jin
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gangjin Yu
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tairan Yuwen
- Department of Pharmaceutical Analysis & State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100871, China
| | - Dawei Gao
- State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Hebei 066004, China
| | - Guan Wang
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yilin Zhou
- College of Chemistry, Central China Normal University, Wuhan 430079, China
| | - Bin Jiang
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xu Zhang
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Conggang Li
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lichun He
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Hubei 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Optics Valley Laboratory, Hubei 430074, China
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6
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Das J, Tiwari M, Subramanyam D. Clathrin Light Chains: Not to Be Taken so Lightly. Front Cell Dev Biol 2022; 9:774587. [PMID: 34970544 PMCID: PMC8712872 DOI: 10.3389/fcell.2021.774587] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 11/12/2021] [Indexed: 01/31/2023] Open
Abstract
Clathrin is a cytosolic protein involved in the intracellular trafficking of a wide range of cargo. It is composed of three heavy chains and three light chains that together form a triskelion, the subunit that polymerizes to form a clathrin coated vesicle. In addition to its role in membrane trafficking, clathrin is also involved in various cellular and biological processes such as chromosomal segregation during mitosis and organelle biogenesis. Although the role of the heavy chains in regulating important physiological processes has been well documented, we still lack a complete understanding of how clathrin light chains regulate membrane traffic and cell signaling. This review highlights the importance and contributions of clathrin light chains in regulating clathrin assembly, vesicle formation, endocytosis of selective receptors and physiological and developmental processes.
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Affiliation(s)
- Jyoti Das
- National Centre for Cell Science, Pune, India.,Savitribai Phule Pune University, Pune, India
| | - Mahak Tiwari
- National Centre for Cell Science, Pune, India.,Savitribai Phule Pune University, Pune, India
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7
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Li C, Shi L, Gao Y, Lu Y, Ye J, Liu X. HSC70 Inhibits Spring Viremia of Carp Virus Replication by Inducing MARCH8-Mediated Lysosomal Degradation of G Protein. Front Immunol 2021; 12:724403. [PMID: 34659210 PMCID: PMC8511485 DOI: 10.3389/fimmu.2021.724403] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 09/10/2021] [Indexed: 11/13/2022] Open
Abstract
As a fierce pathogen, spring viremia of carp virus (SVCV) can cause high mortality in the common carp, and its glycoprotein (G protein) is a component of the viral structure on the surface of virion, which is crucial in viral life cycle. This report adopted tandem affinity purification (TAP), mass spectrometry analysis (LC-MS/MS), immunoprecipitation, and confocal microscopy assays to identify Heat shock cognate protein 70 (HSC70) as an interaction partner of SVCV G protein. It was found that HSC70 overexpression dramatically inhibited SVCV replication, whereas its loss of functions elicited opposing effects on SVCV replication. Mechanistic studies indicate that HSC70 induces lysosomal degradation of ubiquitinated-SVCV G protein. This study further demonstrates that Membrane-associated RING-CH 8 (MARCH8), an E3 ubiquitin ligase, is critical for SVCV G protein ubiquitylation and leads to its lysosomal degradation. Furthermore, the MARCH8 mediated ubiquitylation of SVCV G protein required the participation of HSC70 through forming a multicomponent complex. Taken together, these results demonstrate that HSC70 serves as a scaffold for MARCH8 and SVCV G, which leads to the ubiquitylation and degradation of SVCV G protein and thus inhibits viral replication. These findings have established a novel host defense mechanism against SVCV.
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Affiliation(s)
- Chen Li
- State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China.,Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
| | - Lin Shi
- State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China.,Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
| | - Yan Gao
- State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China.,Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
| | - Yuanan Lu
- Department of Public Health Sciences, University of Hawaii at Manoa, Honolulu, HI, United States
| | - Jing Ye
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Xueqin Liu
- State Key Laboratory of Agricultural Microbiology, College of Fisheries, Huazhong Agricultural University, Wuhan, China.,Hubei Engineering Technology Research Center for Aquatic Animal Diseases Control and Prevention, Wuhan, China
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8
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Clathrin: the molecular shape shifter. Biochem J 2021; 478:3099-3123. [PMID: 34436540 DOI: 10.1042/bcj20200740] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 07/19/2021] [Accepted: 08/04/2021] [Indexed: 12/11/2022]
Abstract
Clathrin is best known for its contribution to clathrin-mediated endocytosis yet it also participates to a diverse range of cellular functions. Key to this is clathrin's ability to assemble into polyhedral lattices that include curved football or basket shapes, flat lattices or even tubular structures. In this review, we discuss clathrin structure and coated vesicle formation, how clathrin is utilised within different cellular processes including synaptic vesicle recycling, hormone desensitisation, spermiogenesis, cell migration and mitosis, and how clathrin's remarkable 'shapeshifting' ability to form diverse lattice structures might contribute to its multiple cellular functions.
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9
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Kohler V, Andréasson C. Hsp70-mediated quality control: should I stay or should I go? Biol Chem 2021; 401:1233-1248. [PMID: 32745066 DOI: 10.1515/hsz-2020-0187] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 07/11/2020] [Indexed: 12/30/2022]
Abstract
Chaperones of the 70 kDa heat shock protein (Hsp70) superfamily are key components of the cellular proteostasis system. Together with its co-chaperones, Hsp70 forms proteostasis subsystems that antagonize protein damage during physiological and stress conditions. This function stems from highly regulated binding and release cycles of protein substrates, which results in a flow of unfolded, partially folded and misfolded species through the Hsp70 subsystem. Specific factors control how Hsp70 makes decisions regarding folding and degradation fates of the substrate proteins. In this review, we summarize how the flow of Hsp70 substrates is controlled in the cell with special emphasis on recent advances regarding substrate release mechanisms.
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Affiliation(s)
- Verena Kohler
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-106 91 Stockholm, Sweden
| | - Claes Andréasson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-106 91 Stockholm, Sweden
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10
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Mathangasinghe Y, Fauvet B, Jane SM, Goloubinoff P, Nillegoda NB. The Hsp70 chaperone system: distinct roles in erythrocyte formation and maintenance. Haematologica 2021; 106:1519-1534. [PMID: 33832207 PMCID: PMC8168490 DOI: 10.3324/haematol.2019.233056] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Indexed: 01/14/2023] Open
Abstract
Erythropoiesis is a tightly regulated cell differentiation process in which specialized oxygen- and carbon dioxide-carrying red blood cells are generated in vertebrates. Extensive reorganization and depletion of the erythroblast proteome leading to the deterioration of general cellular protein quality control pathways and rapid hemoglobin biogenesis rates could generate misfolded/aggregated proteins and trigger proteotoxic stresses during erythropoiesis. Such cytotoxic conditions could prevent proper cell differentiation resulting in premature apoptosis of erythroblasts (ineffective erythropoiesis). The heat shock protein 70 (Hsp70) molecular chaperone system supports a plethora of functions that help maintain cellular protein homeostasis (proteostasis) and promote red blood cell differentiation and survival. Recent findings show that abnormalities in the expression, localization and function of the members of this chaperone system are linked to ineffective erythropoiesis in multiple hematological diseases in humans. In this review, we present latest advances in our understanding of the distinct functions of this chaperone system in differentiating erythroblasts and terminally differentiated mature erythrocytes. We present new insights into the protein repair-only function(s) of the Hsp70 system, perhaps to minimize protein degradation in mature erythrocytes to warrant their optimal function and survival in the vasculature under healthy conditions. The work also discusses the modulatory roles of this chaperone system in a wide range of hematological diseases and the therapeutic gain of targeting Hsp70.
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Affiliation(s)
| | - Bruno Fauvet
- Department of Plant Molecular Biology, Lausanne University, Lausanne
| | - Stephen M Jane
- Central Clinical School, Monash University, Prahran, Victoria, Australia; Department of Hematology, Alfred Hospital, Monash University, Prahran, Victoria
| | | | - Nadinath B Nillegoda
- Australian Regenerative Medicine Institute, Monash University, Clayton, Victoria.
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11
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Lu J, Zhang X, Wu Y, Sheng Y, Li W, Wang W. Energy landscape remodeling mechanism of Hsp70-chaperone-accelerated protein folding. Biophys J 2021; 120:1971-1983. [PMID: 33745889 PMCID: PMC8204389 DOI: 10.1016/j.bpj.2021.03.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/02/2021] [Accepted: 03/12/2021] [Indexed: 11/29/2022] Open
Abstract
Hsp70 chaperone is one of the key protein machines responsible for the quality control of protein production in cells. Facilitating in vivo protein folding by counteracting misfolding and aggregation is the essence of its biological function. Although the allosteric cycle during its functional actions has been well characterized both experimentally and computationally, the mechanism by which Hsp70 assists protein folding is still not fully understood. In this work, we studied the Hsp70-mediated folding of model proteins with rugged energy landscape by using molecular simulations. Different from the canonical scenario of Hsp70 functioning, which assumes that folding of substrate proteins occurs spontaneously after releasing from chaperones, our results showed that the substrate protein remains in contacts with the chaperone during its folding process. The direct chaperone-substrate interactions in the open conformation of Hsp70 tend to shield the substrate sites prone to form non-native contacts, which therefore avoids the frustrated folding pathway, leading to a higher folding rate and less probability of misfolding. Our results suggest that in addition to the unfoldase and holdase functions widely addressed in previous studies, Hsp70 can facilitate the folding of its substrate proteins by remodeling the folding energy landscape and directing the folding processes, demonstrating the foldase scenario. These findings add new, to our knowledge, insights into the general molecular mechanisms of chaperone-mediated protein folding.
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Affiliation(s)
- Jiajun Lu
- Department of Physics, National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Xiaoyi Zhang
- Department of Physics, National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Yichao Wu
- Department of Physics, National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Yuebiao Sheng
- Department of Physics, National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China
| | - Wenfei Li
- Department of Physics, National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
| | - Wei Wang
- Department of Physics, National Laboratory of Solid State Microstructure, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.
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12
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Mallery DL, Kleinpeter AB, Renner N, Faysal KMR, Novikova M, Kiss L, Wilson MSC, Ahsan B, Ke Z, Briggs JAG, Saiardi A, Böcking T, Freed EO, James LC. A stable immature lattice packages IP 6 for HIV capsid maturation. SCIENCE ADVANCES 2021; 7:7/11/eabe4716. [PMID: 33692109 PMCID: PMC7946374 DOI: 10.1126/sciadv.abe4716] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/21/2021] [Indexed: 05/05/2023]
Abstract
HIV virion assembly begins with the construction of an immature lattice consisting of Gag hexamers. Upon virion release, protease-mediated Gag cleavage leads to a maturation event in which the immature lattice disassembles and the mature capsid assembles. The cellular metabolite inositiol hexakisphosphate (IP6) and maturation inhibitors (MIs) both bind and stabilize immature Gag hexamers, but whereas IP6 promotes virus maturation, MIs inhibit it. Here we show that HIV is evolutionarily constrained to maintain an immature lattice stability that ensures IP6 packaging without preventing maturation. Replication-deficient mutant viruses with reduced IP6 recruitment display increased infectivity upon treatment with the MI PF46396 (PF96) or the acquisition of second-site compensatory mutations. Both PF96 and second-site mutations stabilise the immature lattice and restore IP6 incorporation, suggesting that immature lattice stability and IP6 binding are interdependent. This IP6 dependence suggests that modifying MIs to compete with IP6 for Gag hexamer binding could substantially improve MI antiviral potency.
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Affiliation(s)
- Donna L Mallery
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Alex B Kleinpeter
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Nadine Renner
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - K M Rifat Faysal
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Mariia Novikova
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Leo Kiss
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Miranda S C Wilson
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Bilal Ahsan
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Zunlong Ke
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - John A G Briggs
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Adolfo Saiardi
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA.
| | - Leo C James
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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13
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Renner N, Mallery DL, Faysal KMR, Peng W, Jacques DA, Böcking T, James LC. A lysine ring in HIV capsid pores coordinates IP6 to drive mature capsid assembly. PLoS Pathog 2021; 17:e1009164. [PMID: 33524070 PMCID: PMC7850482 DOI: 10.1371/journal.ppat.1009164] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/13/2020] [Indexed: 02/07/2023] Open
Abstract
The HIV capsid self-assembles a protective conical shell that simultaneously prevents host sensing whilst permitting the import of nucleotides to drive DNA synthesis. This is accomplished through the construction of dynamic, highly charged pores at the centre of each capsid multimer. The clustering of charges required for dNTP import is strongly destabilising and it is proposed that HIV uses the metabolite IP6 to coordinate the pore during assembly. Here we have investigated the role of inositol phosphates in coordinating a ring of positively charged lysine residues (K25) that forms at the base of the capsid pore. We show that whilst IP5, which can functionally replace IP6, engages an arginine ring (R18) at the top of the pore, the lysine ring simultaneously binds a second IP5 molecule. Dose dependent removal of K25 from the pore severely inhibits HIV infection and concomitantly prevents DNA synthesis. Cryo-tomography reveals that K25A virions have a severe assembly defect that inhibits the formation of mature capsid cones. Monitoring both the kinetics and morphology of capsids assembled in vitro reveals that while mutation K25A can still form tubes, the ability of IP6 to drive assembly of capsid cones has been lost. Finally, in single molecule TIRF microscopy experiments, capsid lattices in permeabilised K25 mutant virions are rapidly lost and cannot be stabilised by IP6. These results suggest that the coordination of IP6 by a second charged ring in mature hexamers drives the assembly of conical capsids capable of reverse transcription and infection.
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Affiliation(s)
- Nadine Renner
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | | | - K. M. Rifat Faysal
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Australia
| | - Wang Peng
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Australia
| | - David A. Jacques
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Australia
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Australia
| | - Leo C. James
- MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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14
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He K, Song E, Upadhyayula S, Dang S, Gaudin R, Skillern W, Bu K, Capraro BR, Rapoport I, Kusters I, Ma M, Kirchhausen T. Dynamics of Auxilin 1 and GAK in clathrin-mediated traffic. J Cell Biol 2020; 219:133624. [PMID: 31962345 PMCID: PMC7054993 DOI: 10.1083/jcb.201908142] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/28/2019] [Accepted: 12/15/2019] [Indexed: 01/08/2023] Open
Abstract
Clathrin-coated vesicles lose their clathrin lattice within seconds of pinching off, through the action of the Hsc70 “uncoating ATPase.” The J- and PTEN-like domain–containing proteins, auxilin 1 (Aux1) and auxilin 2 (GAK), recruit Hsc70. The PTEN-like domain has no phosphatase activity, but it can recognize phosphatidylinositol phosphate head groups. Aux1 and GAK appear on coated vesicles in successive transient bursts, immediately after dynamin-mediated membrane scission has released the vesicle from the plasma membrane. These bursts contain a very small number of auxilins, and even four to six molecules are sufficient to mediate uncoating. In contrast, we could not detect auxilins in abortive pits or at any time during coated pit assembly. We previously showed that clathrin-coated vesicles have a dynamic phosphoinositide landscape, and we have proposed that lipid head group recognition might determine the timing of Aux1 and GAK appearance. The differential recruitment of Aux1 and GAK correlates with temporal variations in phosphoinositide composition, consistent with a lipid-switch timing mechanism.
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Affiliation(s)
- Kangmin He
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA.,Department of Pediatrics, Harvard Medical School, Boston, MA
| | - Eli Song
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA
| | - Srigokul Upadhyayula
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA.,Department of Pediatrics, Harvard Medical School, Boston, MA
| | - Song Dang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA
| | - Raphael Gaudin
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA
| | - Wesley Skillern
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA
| | - Kevin Bu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA
| | | | - Iris Rapoport
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Ilja Kusters
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA
| | - Minghe Ma
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA
| | - Tom Kirchhausen
- Department of Cell Biology, Harvard Medical School, Boston, MA.,Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA.,Department of Pediatrics, Harvard Medical School, Boston, MA
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15
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Quantitative Synaptic Biology: A Perspective on Techniques, Numbers and Expectations. Int J Mol Sci 2020; 21:ijms21197298. [PMID: 33023247 PMCID: PMC7582872 DOI: 10.3390/ijms21197298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/24/2020] [Accepted: 09/28/2020] [Indexed: 12/31/2022] Open
Abstract
Synapses play a central role for the processing of information in the brain and have been analyzed in countless biochemical, electrophysiological, imaging, and computational studies. The functionality and plasticity of synapses are nevertheless still difficult to predict, and conflicting hypotheses have been proposed for many synaptic processes. In this review, we argue that the cause of these problems is a lack of understanding of the spatiotemporal dynamics of key synaptic components. Fortunately, a number of emerging imaging approaches, going beyond super-resolution, should be able to provide required protein positions in space at different points in time. Mathematical models can then integrate the resulting information to allow the prediction of the spatiotemporal dynamics. We argue that these models, to deal with the complexity of synaptic processes, need to be designed in a sufficiently abstract way. Taken together, we suggest that a well-designed combination of imaging and modelling approaches will result in a far more complete understanding of synaptic function than currently possible.
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16
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Dynamics of the HIV Gag Lattice Detected by Localization Correlation Analysis and Time-Lapse iPALM. Biophys J 2020; 119:581-592. [PMID: 32652060 PMCID: PMC7399489 DOI: 10.1016/j.bpj.2020.06.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 05/31/2020] [Accepted: 06/02/2020] [Indexed: 01/09/2023] Open
Abstract
Immature human immunodeficiency virus (HIV) virions have a lattice of Gag and Gag-Pol proteins anchored to the lumen of their envelope. Using electron microscopy, we demonstrate that HIV virus-like particles (VLPs) assembled by the viral protein Gag and tagged at its C-terminus with the fluorescent protein Dendra2 have the same morphology and size as the VLPs assembled using only HIV Gag. We characterize the photophysical properties of Dendra2 and demonstrate that 60% of Dendra2 molecules can be photoswitched and reliably counted in our interferometric photoactivated localization microscopy (iPALM) setup. We further perform iPALM imaging on immobilized HIV Gag-Dendra2 VLPs and demonstrate that we can localize and count 900–1600 Dendra2 molecules within each immobilized VLP with a single-molecule localization precision better than (10 nm)3. Our molecular counts correspond to 1400–2400 Gag-Dendra2 proteins incorporated within each VLP. We further calculate temporal correlation functions of localization data, which we present as localization correlation analysis, and show dynamics within the lattice of immobilized VLPs in the timescale of 10–100 s. We further use our localization data to reconstruct time-lapse iPALM images of the Gag-Dendra2 lattice within the lumen of immobilized VLPs. The iPALM time-lapse images show significant lattice dynamics within the lumen of VLPs. Addition of disuccinimidyl suberate to the VLPs completely abrogated these dynamics as observed in both localization correlation analysis and time-lapse iPALM. In a complementary approach, we utilized HaXS8 cross-linking reactions between Halo and SNAP proteins and verified lattice dynamics in purified VLPs incorporating 10% Gag-SNAP, 10% Gag-Halo, and 80% Gag proteins. The HIV Gag lattice, along with the structural lattice of other enveloped viruses, has been mostly considered static. Our study provides an important tool to investigate the dynamics within these enveloped viruses.
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17
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Yang J, Xu Y, Yan Y, Li W, Zhao L, Dai Q, Li Y, Li S, Zhong J, Cao R, Zhong W. Small Molecule Inhibitor of ATPase Activity of HSP70 as a Broad-Spectrum Inhibitor against Flavivirus Infections. ACS Infect Dis 2020; 6:832-843. [PMID: 31967789 DOI: 10.1021/acsinfecdis.9b00376] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Flaviviruses including Zika virus, Dengue virus, Japanese Encephalitis virus, and Yellow Fever virus cause heavy burdens to public health around the world. No specific antiviral drug is available in the clinic against these flavivirus infections. Heat-shock protein 70 (HSP70) has recently been proven to be a promising antiviral target against Zika virus and Dengue virus. Here, we report that Apoptozole, a small molecule inhibitor of ATPase activity of HSP70, has broad-spectrum anti-flavivirus potential. The mode of action analysis revealed that Apoptozole acted at the post-entry step. Transcriptome analysis revealed that genes related to cholesterol metabolism, fatty acid synthesis, and innate immunity were differentially expressed after treatment with Apoptozole. In vivo data suggested Apoptozole exerted protection effects against Zika virus (ZIKV) infection in a mouse model by enhancing the innate immune response, which suggested a novel anti-ZIKV mechanism of HSP70 inhibitors.
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Affiliation(s)
- Jingjing Yang
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Yongfen Xu
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yunzheng Yan
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Wei Li
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Lei Zhao
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Qingsong Dai
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Yuexiang Li
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Song Li
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Jin Zhong
- CAS Key Laboratory of Molecular Virology and Immunology, Unit of Viral Hepatitis, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ruiyuan Cao
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
| | - Wu Zhong
- National Engineering Research Center for the Emergency Drug, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China
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18
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Rosenzweig R, Nillegoda NB, Mayer MP, Bukau B. The Hsp70 chaperone network. Nat Rev Mol Cell Biol 2020; 20:665-680. [PMID: 31253954 DOI: 10.1038/s41580-019-0133-3] [Citation(s) in RCA: 639] [Impact Index Per Article: 159.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The 70-kDa heat shock proteins (Hsp70s) are ubiquitous molecular chaperones that act in a large variety of cellular protein folding and remodelling processes. They function virtually at all stages of the life of proteins from synthesis to degradation and are thus crucial for maintaining protein homeostasis, with direct implications for human health. A large set of co-chaperones comprising J-domain proteins and nucleotide exchange factors regulate the ATPase cycle of Hsp70s, which is allosterically coupled to substrate binding and release. Moreover, Hsp70s cooperate with other cellular chaperone systems including Hsp90, Hsp60 chaperonins, small heat shock proteins and Hsp100 AAA+ disaggregases, together constituting a dynamic and functionally versatile network for protein folding, unfolding, regulation, targeting, aggregation and disaggregation, as well as degradation. In this Review we describe recent advances that have increased our understanding of the molecular mechanisms and working principles of the Hsp70 network. This knowledge showcases how the Hsp70 chaperone system controls diverse cellular functions, and offers new opportunities for the development of chemical compounds that modulate disease-related Hsp70 activities.
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Affiliation(s)
- Rina Rosenzweig
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
| | - Nadinath B Nillegoda
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany.,German Cancer Research Center (DKFZ), Heidelberg, Germany.,DKFZ-ZMBH Alliance, Heidelberg, Germany.,Australian Regenerative Medicine Institute (ARMI), Monash University, Clayton, VIC, Australia
| | - Matthias P Mayer
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany.,DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany. .,German Cancer Research Center (DKFZ), Heidelberg, Germany. .,DKFZ-ZMBH Alliance, Heidelberg, Germany.
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19
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Narasimhan M, Johnson A, Prizak R, Kaufmann WA, Tan S, Casillas-Pérez B, Friml J. Evolutionarily unique mechanistic framework of clathrin-mediated endocytosis in plants. eLife 2020; 9:52067. [PMID: 31971511 PMCID: PMC7012609 DOI: 10.7554/elife.52067] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 01/22/2020] [Indexed: 12/13/2022] Open
Abstract
In plants, clathrin mediated endocytosis (CME) represents the major route for cargo internalisation from the cell surface. It has been assumed to operate in an evolutionary conserved manner as in yeast and animals. Here we report characterisation of ultrastructure, dynamics and mechanisms of plant CME as allowed by our advancement in electron microscopy and quantitative live imaging techniques. Arabidopsis CME appears to follow the constant curvature model and the bona fide CME population generates vesicles of a predominantly hexagonal-basket type; larger and with faster kinetics than in other models. Contrary to the existing paradigm, actin is dispensable for CME events at the plasma membrane but plays a unique role in collecting endocytic vesicles, sorting of internalised cargos and directional endosome movement that itself actively promote CME events. Internalized vesicles display a strongly delayed and sequential uncoating. These unique features highlight the independent evolution of the plant CME mechanism during the autonomous rise of multicellularity in eukaryotes.
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Affiliation(s)
| | - Alexander Johnson
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Roshan Prizak
- Institute of Science and Technology Austria, Klosterneuburg, Austria.,Institute of Biological and Chemical Systems - Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | | | - Shutang Tan
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | | | - Jiří Friml
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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20
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Lai MC, Chen HH, Xu P, Wang RYL. Translation control of Enterovirus A71 gene expression. J Biomed Sci 2020; 27:22. [PMID: 31910851 PMCID: PMC6947814 DOI: 10.1186/s12929-019-0607-9] [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: 07/05/2019] [Accepted: 12/19/2019] [Indexed: 12/13/2022] Open
Abstract
Upon EV-A71 infection of a host cell, EV-A71 RNA is translated into a viral polyprotein. Although EV-A71 can use the cellular translation machinery to produce viral proteins, unlike cellular translation, which is cap-dependent, the viral RNA genome of EV-A71 does not contain a 5′ cap and the translation of EV-A71 protein is cap-independent, which is mediated by the internal ribosomal entry site (IRES) located in the 5′ UTR of EV-A71 mRNA. Like many other eukaryotic viruses, EV-A71 manipulates the host cell translation devices, using an elegant RNA-centric strategy in infected cells. During viral translation, viral RNA plays an important role in controlling the stage of protein synthesis. In addition, due to the cellular defense mechanism, viral replication is limited by down-regulating translation. EV-A71 also utilizes protein factors in the host to overcome antiviral responses or even use them to promote viral translation rather than host cell translation. In this review, we provide an introduction to the known strategies for EV-A71 to exploit cellular translation mechanisms.
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Affiliation(s)
- Ming-Chih Lai
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, 33302, Taiwan.,Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, 33302, Taiwan.,Department of Colorectal Surgery, Chang Gung Memorial Hospital at Linkou, Taoyuan, 33305, Taiwan
| | - Han-Hsiang Chen
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, 33302, Taiwan
| | - Peng Xu
- Xiangyang No.1 People's Hospital, Hubei University of Medicine, Shiyan, Hubei Province, China.
| | - Robert Y L Wang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, 33302, Taiwan. .,Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, 33302, Taiwan. .,Division of Pediatric Infectious Disease, Department of Pediatrics, Chang Gung Memorial Hospital at Linkou, Taoyuan, 33305, Taiwan.
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21
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Faust O, Rosenzweig R. Structural and Biochemical Properties of Hsp40/Hsp70 Chaperone System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1243:3-20. [DOI: 10.1007/978-3-030-40204-4_1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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22
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Mallery DL, Faysal KMR, Kleinpeter A, Wilson MSC, Vaysburd M, Fletcher AJ, Novikova M, Böcking T, Freed EO, Saiardi A, James LC. Cellular IP 6 Levels Limit HIV Production while Viruses that Cannot Efficiently Package IP 6 Are Attenuated for Infection and Replication. Cell Rep 2019; 29:3983-3996.e4. [PMID: 31851928 PMCID: PMC6931105 DOI: 10.1016/j.celrep.2019.11.050] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 10/11/2019] [Accepted: 11/12/2019] [Indexed: 12/23/2022] Open
Abstract
HIV-1 hijacks host proteins to promote infection. Here we show that HIV is also dependent upon the host metabolite inositol hexakisphosphate (IP6) for viral production and primary cell replication. HIV-1 recruits IP6 into virions using two lysine rings in its immature hexamers. Mutation of either ring inhibits IP6 packaging and reduces viral production. Loss of IP6 also results in virions with highly unstable capsids, leading to a profound loss of reverse transcription and cell infection. Replacement of one ring with a hydrophobic isoleucine core restores viral production, but IP6 incorporation and infection remain impaired, consistent with an independent role for IP6 in stable capsid assembly. Genetic knockout of biosynthetic kinases IPMK and IPPK reveals that cellular IP6 availability limits the production of diverse lentiviruses, but in the absence of IP6, HIV-1 packages IP5 without loss of infectivity. Together, these data suggest that IP6 is a critical cofactor for HIV-1 replication.
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Affiliation(s)
- Donna L Mallery
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - K M Rifat Faysal
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney NSW, Australia
| | - Alex Kleinpeter
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Miranda S C Wilson
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Marina Vaysburd
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - Adam J Fletcher
- MRC Protein Phosphorylation and Ubiquitylation Unit, University of Dundee, Dundee, UK
| | - Mariia Novikova
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney NSW, Australia
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Adolfo Saiardi
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Leo C James
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
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23
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Mortalin restricts porcine epidemic diarrhea virus entry by downregulating clathrin-mediated endocytosis. Vet Microbiol 2019; 239:108455. [PMID: 31767073 DOI: 10.1016/j.vetmic.2019.108455] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/01/2019] [Accepted: 10/07/2019] [Indexed: 12/11/2022]
Abstract
Clathrin-mediated endocytosis is a mechanism used for the invasion of cells by a variety of viruses. Mortalin protein is involved in a variety of cellular functions and plays a role in viral infection. In this study, we found that mortalin significantly inhibited the replication of porcine epidemic diarrhea virus (PEDV) through restricting virus entry. Mechanistically, a biochemical interaction between the carboxyl terminus of mortalin and clathrin heavy chain (CLTC) was been found, and mortalin could induce CLTC degradation through the proteasomal pathway, thereby inhibiting the clathrin-mediated endocytosis of PEDV into host cells. In addition, artificial changes in mortalin expression affected the cell entry of transferrin, further confirming the above results. Finally, we confirmed that this host-mounted antiviral mechanism was broadly applicable to other viruses, such as vesicular stomatitis virus (VSV), rotavirus (RV), and transmissible gastroenteritis virus (TGEV), which use the same clathrin-mediated endocytic to entry. These results reveal a new function of mortalin in inhibiting endocytosis, and provide a novel strategy for treating PEDV infections.
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24
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Chen Y, Yong J, Martínez-Sánchez A, Yang Y, Wu Y, De Camilli P, Fernández-Busnadiego R, Wu M. Dynamic instability of clathrin assembly provides proofreading control for endocytosis. J Cell Biol 2019; 218:3200-3211. [PMID: 31451612 PMCID: PMC6781453 DOI: 10.1083/jcb.201804136] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 06/03/2019] [Accepted: 08/01/2019] [Indexed: 12/18/2022] Open
Abstract
Clathrin-mediated endocytosis depends on the formation of functional clathrin-coated pits that recruit cargos and mediate the uptake of those cargos into the cell. However, it remains unclear whether the cargos in the growing clathrin-coated pits are actively monitored by the coat assembly machinery. Using a cell-free reconstitution system, we report that clathrin coat formation and cargo sorting can be uncoupled, indicating that a checkpoint is required for functional cargo incorporation. We demonstrate that the ATPase Hsc70 and a dynamic exchange of clathrin during assembly are required for this checkpoint. In the absence of Hsc70 function, clathrin assembles into pits but fails to enrich cargo. Using single-molecule imaging, we further show that uncoating takes place throughout the lifetime of the growing clathrin-coated pits. Our results suggest that the dynamic exchange of clathrin, at the cost of the reduced overall assembly rates, primarily serves as a proofreading mechanism for quality control of endocytosis.
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Affiliation(s)
- Yan Chen
- Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore
| | - Jeffery Yong
- Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore
| | | | - Yang Yang
- Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore
| | - Yumei Wu
- Howard Hughes Medical Institute, Department of Cell Biology and Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT
| | - Pietro De Camilli
- Howard Hughes Medical Institute, Department of Cell Biology and Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT
| | - Rubén Fernández-Busnadiego
- Max Planck Institute for Biochemistry, Martinsried, Germany
- Department of Neuropathology, University Medical Center, Georg-August University Göttingen, Göttingen, Germany
| | - Min Wu
- Centre for Bioimaging Sciences, Department of Biological Sciences, National University of Singapore, Singapore
- Mechanobiology Institute, National University of Singapore, Singapore
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25
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Márquez CL, Lau D, Walsh J, Faysal KMR, Parker MW, Turville SG, Böcking T. Fluorescence Microscopy Assay to Measure HIV-1 Capsid Uncoating Kinetics in vitro. Bio Protoc 2019; 9:e3297. [PMID: 33654810 PMCID: PMC7854090 DOI: 10.21769/bioprotoc.3297] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 06/18/2019] [Accepted: 06/25/2019] [Indexed: 11/05/2022] Open
Abstract
The stability of the HIV-1 capsid and the spatiotemporal control of its disassembly, a process called uncoating, need to be finely tuned for infection to proceed. Biochemical methods for measuring capsid lattice disassembly in bulk are unable to resolve intermediates in the uncoating reaction. We have developed a single-particle fluorescence microscopy method to follow the real-time uncoating kinetics of authentic HIV capsids in vitro. The assay utilizes immobilized viral particles that are permeabilized with the a pore-former protein, and is designed to (1) detect the first defect of the capsid by the release of a solution phase marker (GFP) and (2) visualize the disassembly of the capsid over time by “painting” the capsid lattice with labeled cyclophilin A (CypA), a protein that binds weakly to the outside of the capsid. This novel assay allows the study of dynamic interactions of molecules with hundreds of individual capsids as well as to determine their effect on viral capsid stability, which provides a powerful tool for dissecting uncoating mechanisms and for the development of capsid-binding drugs.
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Affiliation(s)
- Chantal L Márquez
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - Derrick Lau
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - James Walsh
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - K M Rifat Faysal
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - Michael W Parker
- St. Vincent's Institute of Medical Research, Australia; Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Australia
| | | | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
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26
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Hsp70 molecular chaperones: multifunctional allosteric holding and unfolding machines. Biochem J 2019; 476:1653-1677. [PMID: 31201219 DOI: 10.1042/bcj20170380] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/17/2019] [Accepted: 05/21/2019] [Indexed: 12/20/2022]
Abstract
The Hsp70 family of chaperones works with its co-chaperones, the nucleotide exchange factors and J-domain proteins, to facilitate a multitude of cellular functions. Central players in protein homeostasis, these jacks-of-many-trades are utilized in a variety of ways because of their ability to bind with selective promiscuity to regions of their client proteins that are exposed when the client is unfolded, either fully or partially, or visits a conformational state that exposes the binding region in a regulated manner. The key to Hsp70 functions is that their substrate binding is transient and allosterically cycles in a nucleotide-dependent fashion between high- and low-affinity states. In the past few years, structural insights into the molecular mechanism of this allosterically regulated binding have emerged and provided deep insight into the deceptively simple Hsp70 molecular machine that is so widely harnessed by nature for diverse cellular functions. In this review, these structural insights are discussed to give a picture of the current understanding of how Hsp70 chaperones work.
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27
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Abstract
Biological molecules are often highly dynamic, and this flexibility can be critical for function. The large range of sampled timescales and the fact that many of the conformers that are continually explored are only transiently formed and sparsely populated challenge current biophysical approaches. Solution nuclear magnetic resonance (NMR) spectroscopy has emerged as a powerful method for characterizing biomolecular dynamics in detail, even in cases where excursions involve short-lived states. Here, we briefly review a number of NMR experiments for studies of biomolecular dynamics on the microsecond-to-second timescale and focus on applications to protein and nucleic acid systems that clearly illustrate the functional relevance of motion in both health and disease.
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Affiliation(s)
- Ashok Sekhar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Lewis E. Kay
- Departments of Molecular Genetics, Biochemistry, and Chemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
- Program in Molecular Medicine, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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28
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Reconstitution of Clathrin Coat Disassembly for Fluorescence Microscopy and Single-Molecule Analysis. Methods Mol Biol 2019; 1847:121-146. [PMID: 30129014 DOI: 10.1007/978-1-4939-8719-1_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
The disassembly of the clathrin lattice surrounding coated vesicles is the obligatory last step in their life cycle. It is mediated by the coordinated recruitment of auxilin and Hsc70, an ATP-driven molecular clamp. Here, we describe the preparation of reagents and the single-particle fluorescence microscopy imaging assay in which we visualize directly the Hsc70-driven uncoating of synthetic clathrin coats or clathrin-coated vesicles.
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29
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Abstract
High-resolution fluorescence microscopy is increasingly contributing to our understanding of molecular processes. By utilizing single-molecule intensity information, imaging experiments can be rendered quantitative, yielding insights into the stoichiometry and kinetics of the components of a molecular assembly. Here, we describe the experimental and analytical steps needed to study the assembly of clathrin-coated vesicles with single-molecule resolution, using total internal reflection fluorescence microscopy. Many components of the protocol are broadly applicable to the characterization of other molecular processes.
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30
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Marsland R, England JL. Active regeneration unites high- and low-temperature features in cooperative self-assembly. Phys Rev E 2019; 98:022411. [PMID: 30253561 DOI: 10.1103/physreve.98.022411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Indexed: 12/29/2022]
Abstract
Cytoskeletal filaments are capable of self-assembly in the absence of externally supplied chemical energy, but the rapid turnover rates essential for their biological function require a constant flux of adenosine triphosphate (ATP) or guanosine triphosphate (GTP) hydrolysis. The same is true for two-dimensional protein assemblies employed in the formation of vesicles from cellular membranes, which rely on ATP-hydrolyzing enzymes to rapidly disassemble upon completion of the process. Recent observations suggest that the nucleolus, p granules, and other three-dimensional membraneless organelles may also demand dissipation of chemical energy to maintain their fluidity. Cooperative binding plays a crucial role in the dynamics of these higher-dimensional structures, but is absent from classic models of one-dimensional cytoskeletal assembly. In this paper, we present a thermodynamically consistent model of active regeneration with cooperative assembly, and compute the maximum turnover rate and minimum disassembly time as a function of the chemical driving force and the binding energy. We find that these driven structures resemble different equilibrium states above and below the nucleation barrier. In particular, we show that the maximal acceleration under large binding energies unites infinite-temperature local fluctuations with low-temperature nucleation kinetics.
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Affiliation(s)
- Robert Marsland
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, 400 Technology Square, Cambridge, Massachusetts 02139, USA
| | - Jeremy L England
- Physics of Living Systems Group, Department of Physics, Massachusetts Institute of Technology, 400 Technology Square, Cambridge, Massachusetts 02139, USA
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31
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Janco M, Böcking T, He S, Coster ACF. Interactions of tropomyosin Tpm1.1 on a single actin filament: A method for extraction and processing of high resolution TIRF microscopy data. PLoS One 2018; 13:e0208586. [PMID: 30532204 PMCID: PMC6287813 DOI: 10.1371/journal.pone.0208586] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 11/20/2018] [Indexed: 12/14/2022] Open
Abstract
Skeletal muscle tropomyosin (Tpm1.1) is an elongated, rod-shaped, alpha-helical coiled-coil protein that forms continuous head-to-tail polymers along both sides of the actin filament. In this study we use single molecule fluorescence TIRF microscopy combined with a microfluidic device and fluorescently labelled proteins to measure Tpm1.1 association to and dissociation from single actin filaments. Our experimental setup allows us to clearly resolve Tpm1.1 interactions on both sides of the filaments. Here we provide a semi-automated method for the extraction and quantification of kymograph data for individual actin filaments bound at different Tpm1.1 concentrations. We determine boundaries on the kymograph on each side of the actin filament, based on intensity thresholding, performing fine manual editing of the boundaries (if needed) and extracting user defined kinetic properties of the system. Using our analytical tools we can determine (i) nucleation point(s) and rates, (ii) elongation rates of Tpm1.1, (iii) identify meeting points after the saturation of filament, and when dissociation occurs, (iv) initiation point(s), (v) the final dissociation point(s), as well as (vi) dissociation rates. All of these measurements can be extracted from both sides of the filament, allowing for the determination of possible differences in behaviour on the two sides of the filament, and across concentrations. The robust and repeatable nature of the method allows quantitative, semi-automated analyses to be made of large studies of acto-tropomyosin interactions, as well as for other actin binding proteins or filamentous structures, opening the way for dissection of the dynamics underlying these interactions.
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Affiliation(s)
- Miro Janco
- Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia
| | - Till Böcking
- Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, University of New South Wales, Sydney, New South Wales, Australia
| | - Stanley He
- School of Mathematics & Statistics, University of New South Wales, Sydney, New South Wales, Australia
| | - Adelle C. F. Coster
- School of Mathematics & Statistics, University of New South Wales, Sydney, New South Wales, Australia
- * E-mail:
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32
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Mayer MP, Gierasch LM. Recent advances in the structural and mechanistic aspects of Hsp70 molecular chaperones. J Biol Chem 2018; 294:2085-2097. [PMID: 30455352 DOI: 10.1074/jbc.rev118.002810] [Citation(s) in RCA: 169] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hsp70 chaperones are central hubs of the protein quality control network and collaborate with co-chaperones having a J-domain (an ∼70-residue-long helical hairpin with a flexible loop and a conserved His-Pro-Asp motif required for ATP hydrolysis by Hsp70s) and also with nucleotide exchange factors to facilitate many protein-folding processes that (re)establish protein homeostasis. The Hsp70s are highly dynamic nanomachines that modulate the conformation of their substrate polypeptides by transiently binding to short, mostly hydrophobic stretches. This interaction is regulated by an intricate allosteric mechanism. The J-domain co-chaperones target Hsp70 to their polypeptide substrates, and the nucleotide exchange factors regulate the lifetime of the Hsp70-substrate complexes. Significant advances in recent years are beginning to unravel the molecular mechanism of this chaperone machine and how they treat their substrate proteins.
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Affiliation(s)
- Matthias P Mayer
- From the Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, 69120 Heidelberg, Germany and
| | - Lila M Gierasch
- the Departments of Biochemistry and Molecular Biology and.,Chemistry, University of Massachusetts, Amherst, Massachusetts 01003
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33
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Zhao M, Nicovich PR, Janco M, Deng Q, Yang Z, Ma Y, Böcking T, Gaus K, Gooding JJ. Ultralow- and Low-Background Surfaces for Single-Molecule Localization Microscopy of Multistep Biointerfaces for Single-Molecule Sensing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:10012-10018. [PMID: 30067032 DOI: 10.1021/acs.langmuir.8b01487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Single-molecule localization microscopy (SMLM) has created the opportunity of pushing fluorescence microscopy from being a biological imaging tool to a surface characterization and possibly even a quantitative analytical tool. The latter could be achieved by molecular counting using pointillist SMLM data sets. However, SMLM is especially sensitive to background fluorescent signals, which influences any subsequent analysis. Therefore, fabricating sensing surfaces that resist nonspecific adsorption of proteins, even after multiple modification steps, has become paramount. Herein is reported two different ways to modify surfaces: dichlorodimethylsilane-biotinylated bovine serum albumin-Tween-20 (DbT20) and poly-l-lysine grafted polyethylene glycol (PLL-PEG) mixed with biotinylated PLL-PEG (PLL-PEG/PEGbiotin). The results show that the ability to resist nonspecific adsorption of DbT20 surfaces deteriorates with an increase in the number of modification steps required after the addition of the DbT20, which limits the applicability of this surface for SMLM. As such, a new surface for SMLM that employs PLL-PEG/PEGbiotin was developed that exhibits ultralow amounts of nonspecific protein adsorption even after many modification steps. The utility of the surface was demonstrated for human influenza hemagglutinin-tagged mEos2, which was directly pulled down from cell lysates onto the PLL-PEG/PEGbiotin surface. The results strongly indicated that the PLL-PEG/PEGbiotin surface satisfies the criteria of SMLM imaging of a negligible background signal and negligible nonspecific adsorption.
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34
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Márquez CL, Lau D, Walsh J, Shah V, McGuinness C, Wong A, Aggarwal A, Parker MW, Jacques DA, Turville S, Böcking T. Kinetics of HIV-1 capsid uncoating revealed by single-molecule analysis. eLife 2018; 7:34772. [PMID: 29877795 PMCID: PMC6039174 DOI: 10.7554/elife.34772] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 06/05/2018] [Indexed: 02/01/2023] Open
Abstract
Uncoating of the metastable HIV-1 capsid is a tightly regulated disassembly process required for release of the viral cDNA prior to nuclear import. To understand the intrinsic capsid disassembly pathway and how it can be modulated, we have developed a single-particle fluorescence microscopy method to follow the real-time uncoating kinetics of authentic HIV capsids in vitro immediately after permeabilizing the viral membrane. Opening of the first defect in the lattice is the rate-limiting step of uncoating, which is followed by rapid, catastrophic collapse. The capsid-binding inhibitor PF74 accelerates capsid opening but stabilizes the remaining lattice. In contrast, binding of a polyanion to a conserved arginine cluster in the lattice strongly delays initiation of uncoating but does not prevent subsequent lattice disassembly. Our observations suggest that different stages of uncoating can be controlled independently with the interplay between different capsid-binding regulators likely to determine the overall uncoating kinetics. Viruses need to enter their host’s cells in order to replicate their genetic material and produce more copies of the virus. A protein shell called a capsid protects the virus during this journey. But the structure of the capsid presents a mystery. How can this protein shell be strong enough to remain intact as it enters a host cell, and yet quickly open up to release the viral genome after replication? Unlike the capsids of many other viruses, those of HIV have irregular structures that rapidly fall apart once removed from the virus. This has thwarted attempts to study intact HIV capsids in order to understand how they work. However, we do know that HIV hijacks a range of molecules produced by the invaded host cell. Dissecting their effects on the capsid is key to understanding how the capsid disassembles. Márquez et al. have now developed a method that can visualize individual HIV capsids – and how they disassemble – in real time using single-molecule microscopy. This revealed that capsids differ widely in their stability. The shell remains closed for a variable period of time and then collapses catastrophically as soon as it loses its first subunit. Using the new technique, Márquez et al. also found that a small molecule drug called PF74 causes the capsid to crack open rapidly, but the remaining shell is then stabilized against further disassembly. These observations reconcile seemingly contradictory observations made by different research groups about how this drug affects the stability of the capsid. The method developed by Márquez et al. enables researchers to measure how molecules produced by host cells interact with the viral capsid, a structure that is fundamental for the virus to establish an infection. It could also be used to test the effects of antiviral drugs that have been designed to target the capsid. The new technique has already been instrumental in related research by Mallery et al., which identifies a molecule found in host cells that stabilizes the capsid of HIV.
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Affiliation(s)
- Chantal L Márquez
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, UNSW, Sydney, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, UNSW, Sydney, Australia
| | - Derrick Lau
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, UNSW, Sydney, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, UNSW, Sydney, Australia
| | - James Walsh
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, UNSW, Sydney, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, UNSW, Sydney, Australia
| | - Vaibhav Shah
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, UNSW, Sydney, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, UNSW, Sydney, Australia
| | - Conall McGuinness
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, UNSW, Sydney, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, UNSW, Sydney, Australia
| | | | | | - Michael W Parker
- Australian Cancer Research Foundation Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Melbourne, Australia.,Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Australia
| | - David A Jacques
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, UNSW, Sydney, Australia
| | | | - Till Böcking
- EMBL Australia Node in Single Molecule Science, School of Medical Sciences, UNSW, Sydney, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, UNSW, Sydney, Australia
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35
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Freilich R, Arhar T, Abrams JL, Gestwicki JE. Protein-Protein Interactions in the Molecular Chaperone Network. Acc Chem Res 2018; 51:940-949. [PMID: 29613769 DOI: 10.1021/acs.accounts.8b00036] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Molecular chaperones play a central role in protein homeostasis (a.k.a. proteostasis) by balancing protein folding, quality control, and turnover. To perform these diverse tasks, chaperones need the malleability to bind nearly any "client" protein and the fidelity to detect when it is misfolded. Remarkably, these activities are carried out by only ∼180 dedicated chaperones in humans. How do a relatively small number of chaperones maintain cellular and organismal proteostasis for an entire proteome? Furthermore, once a chaperone binds a client, how does it "decide" what to do with it? One clue comes from observations that individual chaperones engage in protein-protein interactions (PPIs)-both with each other and with their clients. These physical links coordinate multiple chaperones into organized, functional complexes and facilitate the "handoff" of clients between them. PPIs also link chaperones and their clients to other cellular pathways, such as those that mediate trafficking (e.g., cytoskeleton) and degradation (e.g., proteasome). The PPIs of the chaperone network have a wide range of affinity values (nanomolar to micromolar) and involve many distinct types of domain modules, such as J domains, zinc fingers, and tetratricopeptide repeats. Many of these motifs have the same binding surfaces on shared partners, such that members of one chaperone class often compete for the same interactions. Somehow, this collection of PPIs draws together chaperone families and creates multiprotein subnetworks that are able to make the "decisions" of protein quality control. The key to understanding chaperone-mediated proteostasis might be to understand how PPIs are regulated. This Account will discuss the efforts of our group and others to map, measure, and chemically perturb the PPIs within the molecular chaperone network. Structural biology methods, including X-ray crystallography, NMR spectroscopy, and electron microscopy, have all played important roles in visualizing the chaperone PPIs. Guided by these efforts and -omics approaches to measure PPIs, new advances in high-throughput chemical screening that are specially designed to account for the challenges of this system have emerged. Indeed, chemical biology has played a particularly important role in this effort, as molecules that either promote or inhibit specific PPIs have proven to be invaluable research probes in cells and animals. In addition, these molecules have provided leads for the potential treatment of protein misfolding diseases. One of the major products of this research field has been the identification of putative PPI drug targets within the chaperone network, which might be used to change chaperone "decisions" and rebalance proteostasis.
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Affiliation(s)
- Rebecca Freilich
- Department of Pharmaceutical Chemistry and The Institute for Neurodegenerative Disease, University of California—San Francisco, San Francisco, California 94158, United States
| | - Taylor Arhar
- Department of Pharmaceutical Chemistry and The Institute for Neurodegenerative Disease, University of California—San Francisco, San Francisco, California 94158, United States
| | - Jennifer L. Abrams
- Department of Pharmaceutical Chemistry and The Institute for Neurodegenerative Disease, University of California—San Francisco, San Francisco, California 94158, United States
| | - Jason E. Gestwicki
- Department of Pharmaceutical Chemistry and The Institute for Neurodegenerative Disease, University of California—San Francisco, San Francisco, California 94158, United States
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36
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Rule-based modelling provides an extendable framework for comparing candidate mechanisms underpinning clathrin polymerisation. Sci Rep 2018; 8:5658. [PMID: 29618727 PMCID: PMC5884807 DOI: 10.1038/s41598-018-23829-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 03/19/2018] [Indexed: 01/06/2023] Open
Abstract
Polymerisation of clathrin is a key process that underlies clathrin-mediated endocytosis. Clathrin-coated vesicles are responsible for cell internalization of external substances required for normal homeostasis and life –sustaining activity. There are several hypotheses describing formation of closed clathrin structures. According to one of the proposed mechanisms cage formation may start from a flat lattice buildup on the cellular membrane, which is later transformed into a curved structure. Creation of the curved surface requires rearrangement of the lattice, induced by additional molecular mechanisms. Different potential mechanisms require a modeling framework that can be easily modified to compare between them. We created an extendable rule-based model that describes polymerisation of clathrin molecules and various scenarios of cage formation. Using Global Sensitivity Analysis (GSA) we obtained parameter sets describing clathrin pentagon closure and the emergence/production and closure of large-size clathrin cages/vesicles. We were able to demonstrate that the model can reproduce budding of the clathrin cage from an initial flat array.
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37
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Sekhar A, Velyvis A, Zoltsman G, Rosenzweig R, Bouvignies G, Kay LE. Conserved conformational selection mechanism of Hsp70 chaperone-substrate interactions. eLife 2018; 7:32764. [PMID: 29460778 PMCID: PMC5819949 DOI: 10.7554/elife.32764] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/27/2017] [Indexed: 12/17/2022] Open
Abstract
Molecular recognition is integral to biological function and frequently involves preferred binding of a molecule to one of several exchanging ligand conformations in solution. In such a process the bound structure can be selected from the ensemble of interconverting ligands a priori (conformational selection, CS) or may form once the ligand is bound (induced fit, IF). Here we focus on the ubiquitous and conserved Hsp70 chaperone which oversees the integrity of the cellular proteome through its ATP-dependent interaction with client proteins. We directly quantify the flux along CS and IF pathways using solution NMR spectroscopy that exploits a methyl TROSY effect and selective isotope-labeling methodologies. Our measurements establish that both bacterial and human Hsp70 chaperones interact with clients by selecting the unfolded state from a pre-existing array of interconverting structures, suggesting a conserved mode of client recognition among Hsp70s and highlighting the importance of molecular dynamics in this recognition event. Proteins are the workhorses of a cell and are involved in almost all biological processes. Newly made proteins need to ‘fold’ into precise three-dimensional shapes in order to carry out their roles. However, proteins sometimes fold incorrectly or unfold. These protein forms are not able to work effectively and in some cases may even cause diseases. Chaperone proteins help other proteins to fold correctly and are found in living organisms ranging in complexity from bacteria to humans. There are many different types of chaperones that play different roles inside cells. One, called Hsp70, binds to proteins that are incorrectly folded to help them to mature into their correct structures. However, it was not clear whether Hsp70 can also associate with the mature, correctly folded form of the proteins. A technique called Nuclear Magnetic Resonance (NMR) spectroscopy can distinguish between mature, unfolded and chaperone-bound forms of the same protein. Sekhar et al. therefore used NMR to investigate which forms of a protein Hsp70 binds to. This revealed that both the bacterial and human versions of the Hsp70 chaperone interact only with unfolded proteins. The results presented by Sekhar et al. also explain why Hsp70 does not disrupt the routine workings of the cell: because it does not bind to mature forms of proteins. These observations extend our understanding of how chaperones assist in folding proteins, and fit into a broader research theme exploring how proteins recognize one another. It will now be interesting to see whether the same mechanism holds for more complex forms of proteins, such as aggregates, or larger protein structures with regions of both folded and unfolded elements.
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Affiliation(s)
- Ashok Sekhar
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Algirdas Velyvis
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Guy Zoltsman
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Rina Rosenzweig
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Guillaume Bouvignies
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Univ. Paris 06, CNRS, PSL Research University, Paris, France.,Sorbonne Universités, UPMC Univ. Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules, Paris, France
| | - Lewis E Kay
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada.,Hospital for Sick Children, Program in Molecular Medicine, University Avenue, Toronto, Canada
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38
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Zarouchlioti C, Parfitt DA, Li W, Gittings LM, Cheetham ME. DNAJ Proteins in neurodegeneration: essential and protective factors. Philos Trans R Soc Lond B Biol Sci 2018; 373:20160534. [PMID: 29203718 PMCID: PMC5717533 DOI: 10.1098/rstb.2016.0534] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2017] [Indexed: 12/16/2022] Open
Abstract
Maintenance of protein homeostasis is vitally important in post-mitotic cells, particularly neurons. Neurodegenerative diseases such as polyglutamine expansion disorders-like Huntington's disease or spinocerebellar ataxia (SCA), Alzheimer's disease, fronto-temporal dementia (FTD), amyotrophic lateral sclerosis (ALS) and Parkinson's disease-are often characterized by the presence of inclusions of aggregated protein. Neurons contain complex protein networks dedicated to protein quality control and maintaining protein homeostasis, or proteostasis. Molecular chaperones are a class of proteins with prominent roles in maintaining proteostasis, which act to bind and shield hydrophobic regions of nascent or misfolded proteins while allowing correct folding, conformational changes and enabling quality control. There are many different families of molecular chaperones with multiple functions in proteostasis. The DNAJ family of molecular chaperones is the largest chaperone family and is defined by the J-domain, which regulates the function of HSP70 chaperones. DNAJ proteins can also have multiple other protein domains such as ubiquitin-interacting motifs or clathrin-binding domains leading to diverse and specific roles in the cell, including targeting client proteins for degradation via the proteasome, chaperone-mediated autophagy and uncoating clathrin-coated vesicles. DNAJ proteins can also contain ER-signal peptides or mitochondrial leader sequences, targeting them to specific organelles in the cell. In this review, we discuss the multiple roles of DNAJ proteins and in particular focus on the role of DNAJ proteins in protecting against neurodegenerative diseases caused by misfolded proteins. We also discuss the role of DNAJ proteins as direct causes of inherited neurodegeneration via mutations in DNAJ family genes.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.
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Affiliation(s)
| | - David A Parfitt
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1 V 9EL, UK
| | - Wenwen Li
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1 V 9EL, UK
| | - Lauren M Gittings
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1 V 9EL, UK
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39
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Dong Q, Men R, Dan X, Chen Y, Li H, Chen G, Zee B, Wang MHT, He ML. Hsc70 regulates the IRES activity and serves as an antiviral target of enterovirus A71 infection. Antiviral Res 2017; 150:39-46. [PMID: 29180285 DOI: 10.1016/j.antiviral.2017.11.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 10/23/2017] [Accepted: 11/23/2017] [Indexed: 12/11/2022]
Abstract
Enterovirus A71 (EV-A71) is a small positive-stranded RNA virus that causes human hand, foot and mouth disease (HFMD) and fatal neurological disorders in some cases without effective treatment. Here we show that heat shock cognate protein 70 (Hsc70), a molecular chaperone, displays pivotal role in viral infections. Knockdown of Hsc70 significantly suppresses viral replication evidenced by reducing not only the level of both viral replication intermediates (negative stranded RNA) and viral genomic RNA (positive stranded RNA), but also the level of viral protein expression; whereas ectopic expression of Hsc70 markedly promotes viral replication. Interestingly, depletion of Hsc70 decreases the IRES activity of EV-A71, and the ectopic expression of Hsc70 enhances the IRES activity accordingly. Further study shows that Hsc70 binds viral genomic RNA but does not directly interact with IRES. Moreover, we reveal that Hsc70 interacts with 2A protease and promotes eIF4G cleavage. More importantly, Hsc70 inhibitor Ver-155008 significantly protects cytopathic effects from EV-A71 infection and inhibits both IRES activity and viral reproduction in a dose-dependent manner. The cell viability assay shows that the IC50 and CC50 are 2.01 μM and 47.67 μM, respectively. These results demonstrate not only an important mechanism of Hsc70 in facilitating EV-A71 replication, but also a target for antiviral drug development.
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Affiliation(s)
- Qi Dong
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China
| | - Ruoting Men
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China; Jockey Club of School of Public Health, Chinese University of Hong Kong, Hong Kong, China
| | - Xuelian Dan
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China
| | - Ying Chen
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China
| | - Huangcan Li
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China
| | - Gong Chen
- Departments of Surgery, Faculty of Medicine, Chinese University of Hong Kong, China
| | - Benny Zee
- Jockey Club of School of Public Health, Chinese University of Hong Kong, Hong Kong, China
| | - Maggie H T Wang
- Jockey Club of School of Public Health, Chinese University of Hong Kong, Hong Kong, China.
| | - Ming-Liang He
- Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China; Biotechnology and Health Center, CityU Shenzhen Research Institute, Shenzhen, China.
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40
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Rosenzweig R, Sekhar A, Nagesh J, Kay LE. Promiscuous binding by Hsp70 results in conformational heterogeneity and fuzzy chaperone-substrate ensembles. eLife 2017; 6. [PMID: 28708484 PMCID: PMC5511010 DOI: 10.7554/elife.28030] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 06/28/2017] [Indexed: 01/05/2023] Open
Abstract
The Hsp70 chaperone system is integrated into a myriad of biochemical processes that are critical for cellular proteostasis. Although detailed pictures of Hsp70 bound with peptides have emerged, correspondingly detailed structural information on complexes with folding-competent substrates remains lacking. Here we report a methyl-TROSY based solution NMR study showing that the Escherichia coli version of Hsp70, DnaK, binds to as many as four distinct sites on a small 53-residue client protein, hTRF1. A fraction of hTRF1 chains are also bound to two DnaK molecules simultaneously, resulting in a mixture of DnaK-substrate sub-ensembles that are structurally heterogeneous. The interactions of Hsp70 with a client protein at different sites results in a fuzzy chaperone-substrate ensemble and suggests a mechanism for Hsp70 function whereby the structural heterogeneity of released substrate molecules enables them to circumvent kinetic traps in their conformational free energy landscape and fold efficiently to the native state. DOI:http://dx.doi.org/10.7554/eLife.28030.001
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Affiliation(s)
- Rina Rosenzweig
- Department of Molecular Genetics, The University of Toronto, Toronto, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Ashok Sekhar
- Department of Molecular Genetics, The University of Toronto, Toronto, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada
| | - Jayashree Nagesh
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Canada
| | - Lewis E Kay
- Department of Molecular Genetics, The University of Toronto, Toronto, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Hospital for Sick Children, Program in Molecular Structure and Function, Toronto, Canada
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41
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Abstract
Virus structures were among the earliest illustrations of how regulated protein assembly can proceed by folding of polypeptide-chain segments into complementary sites on partner proteins. I draw on Caspar's image of protein "tentacles" and his metaphor of SV40 pentamers as five-legged, aquatic organisms ("pentopuses") to suggest a helpful vocabulary. "Tentacular interactions" among component subunits organize most subcellular molecular machines. Their selective advantages include facile regulation of both assembly and disassembly by modifying enzymes and by folding chaperones.
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Affiliation(s)
- Stephen C Harrison
- Harvard Medical School, Boston Children's Hospital, and Howard Hughes Medical Institute, 250 Longwood Ave., Boston MA 02115, United States.
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42
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Gorenberg EL, Chandra SS. The Role of Co-chaperones in Synaptic Proteostasis and Neurodegenerative Disease. Front Neurosci 2017; 11:248. [PMID: 28579939 PMCID: PMC5437171 DOI: 10.3389/fnins.2017.00248] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 04/18/2017] [Indexed: 12/14/2022] Open
Abstract
Synapses must be preserved throughout an organism's lifespan to allow for normal brain function and behavior. Synapse maintenance is challenging given the long distances between the termini and the cell body, reliance on axonal transport for delivery of newly synthesized presynaptic proteins, and high rates of synaptic vesicle exo- and endocytosis. Hence, synapses rely on efficient proteostasis mechanisms to preserve their structure and function. To this end, the synaptic compartment has specific chaperones to support its functions. Without proper synaptic chaperone activity, local proteostasis imbalances lead to neurotransmission deficits, dismantling of synapses, and neurodegeneration. In this review, we address the roles of four synaptic chaperones in the maintenance of the nerve terminal, as well as their genetic links to neurodegenerative disease. Three of these are Hsp40 co-chaperones (DNAJs): Cysteine String Protein alpha (CSPα; DNAJC5), auxilin (DNAJC6), and Receptor-Mediated Endocytosis 8 (RME-8; DNAJC13). These co-chaperones contain a conserved J domain through which they form a complex with heat shock cognate 70 (Hsc70), enhancing the chaperone's ATPase activity. CSPα is a synaptic vesicle protein known to chaperone the t-SNARE SNAP-25 and the endocytic GTPase dynamin-1, thereby regulating synaptic vesicle exocytosis and endocytosis. Auxilin binds assembled clathrin cages, and through its interactions with Hsc70 leads to the uncoating of clathrin-coated vesicles, a process necessary for the regeneration of synaptic vesicles. RME-8 is a co-chaperone on endosomes and may have a role in clathrin-coated vesicle endocytosis on this organelle. These three co-chaperones maintain client function by preserving folding and assembly to prevent client aggregation, but they do not break down aggregates that have already formed. The fourth synaptic chaperone we will discuss is Heat shock protein 110 (Hsp110), which interacts with Hsc70, DNAJAs, and DNAJBs to constitute a disaggregase. Hsp110-related disaggregase activity is present at the synapse and is known to protect against aggregation of proteins such as α-synuclein. Congruent with their importance in the nervous system, mutations of these co-chaperones lead to familial neurodegenerative disease. CSPα mutations cause adult neuronal ceroid lipofuscinosis, while auxilin mutations result in early-onset Parkinson's disease, demonstrating their significance in preservation of the nervous system.
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Affiliation(s)
- Erica L Gorenberg
- Interdepartmental Neuroscience Program, Yale UniversityNew Haven, CT, United States
| | - Sreeganga S Chandra
- Department of Neurology, Yale UniversityNew Haven, CT, United States.,Department of Neuroscience, Yale UniversityNew Haven, CT, United States
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43
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Evidence that Hsc70 Is Associated with Cucumber Necrosis Virus Particles and Plays a Role in Particle Disassembly. J Virol 2017; 91:JVI.01555-16. [PMID: 27807229 DOI: 10.1128/jvi.01555-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/25/2016] [Indexed: 11/20/2022] Open
Abstract
Uncoating of a virus particle to expose its nucleic acid is a critical aspect of the viral multiplication cycle, as it is essential for the establishment of infection. In the present study, we investigated the role of plant HSP70 homologs in the uncoating process of Cucumber necrosis virus (CNV), a nonenveloped positive-sense single-stranded RNA [(+)ssRNA] virus having a T=3 icosahedral capsid. We have found through Western blot analysis and mass spectrometry that the HSP70 homolog Hsc70-2 copurifies with CNV particles. Virus overlay and immunogold labeling assays suggest that Hsc70-2 is physically bound to virions. Furthermore, trypsin digestion profiles suggest that the bound Hsc70-2 is partially protected by the virus, indicating an intimate association with particles. In investigating a possible role of Hsc70-2 in particle disassembly, we showed that particles incubated with Hsp70/Hsc70 antibody produce fewer local lesions than those incubated with prebleed control antibody on Chenopodium quinoa In conjunction, CNV virions purified using CsCl and having undetectable amounts of Hsc70-2 produce fewer local lesions. We also have found that plants with elevated levels of HSP70/Hsc70 produce higher numbers of local lesions following CNV inoculation. Finally, incubation of recombinant Nicotiana benthamiana Hsc70-2 with virus particles in vitro leads to conformational changes or partial disassembly of capsids as determined by transmission electron microscopy, and particles are more sensitive to chymotrypsin digestion. This is the first report suggesting that a cellular Hsc70 chaperone is involved in disassembly of a plant virus. IMPORTANCE Virus particles must disassemble and release their nucleic acid in order to establish infection in a cell. Despite the importance of disassembly in the ability of a virus to infect its host, little is known about this process, especially in the case of nonenveloped spherical RNA viruses. Previous work has shown that host HSP70 homologs play multiple roles in the CNV infection cycle. We therefore examined the potential role of these cellular components in the CNV disassembly process. We show that the HSP70 family member Hsc70-2 is physically associated with CNV virions and that HSP70 antibody reduces the ability of CNV to establish infection. Statistically significantly fewer lesions are produced when virions having undetectable HSc70-2 are used as an inoculum. Finally incubation of Hsc70-2 with CNV particles results in conformational changes in particles. Taken together, our data point to an important role of the host factor Hsc70-2 in CNV disassembly.
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44
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Nicovich PR, Janco M, Sobey T, Gajwani M, Obeidy P, Whan R, Gaus K, Gunning PW, Coster AC, Böcking T. Effect of surface chemistry on tropomyosin binding to actin filaments on surfaces. Cytoskeleton (Hoboken) 2016; 73:729-738. [PMID: 27783462 DOI: 10.1002/cm.21342] [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: 06/08/2016] [Revised: 10/24/2016] [Accepted: 10/25/2016] [Indexed: 01/29/2023]
Abstract
Reconstitution of actin filaments on surfaces for observation of filament-associated protein dynamics by fluorescence microscopy is currently an exciting field in biophysics. Here we examine the effects of attaching actin filaments to surfaces on the binding and dissociation kinetics of a fluorescence-labeled tropomyosin, a rod-shaped protein that forms continuous strands wrapping around the actin filament. Two attachment modalities of the actin to the surface are explored: where the actin filament is attached to the surface at multiple points along its length; and where the actin filament is attached at one end and aligned parallel to the surface by buffer flow. To facilitate analysis of actin-binding protein dynamics, we have developed a software tool for the viewing, tracing and analysis of filaments and co-localized species in noisy fluorescence timelapse images. Our analysis shows that the interaction of tropomyosin with actin filaments is similar for both attachment modalities. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Philip R Nicovich
- ARC Centre of Excellence in Advanced Molecular Imaging and EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Miro Janco
- ARC Centre of Excellence in Advanced Molecular Imaging and EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Tom Sobey
- School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Mehul Gajwani
- ARC Centre of Excellence in Advanced Molecular Imaging and EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Peyman Obeidy
- School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Renee Whan
- Biomedical Imaging Facility, University of New South Wales, Sydney, Australia
| | - Katharina Gaus
- ARC Centre of Excellence in Advanced Molecular Imaging and EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Peter W Gunning
- School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Adelle Cf Coster
- School of Mathematics and Statistics, University of New South Wales, Sydney, Australia
| | - Till Böcking
- ARC Centre of Excellence in Advanced Molecular Imaging and EMBL Australia Node in Single Molecule Science, School of Medical Sciences, University of New South Wales, Sydney, Australia
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45
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Aguet F, Upadhyayula S, Gaudin R, Chou YY, Cocucci E, He K, Chen BC, Mosaliganti K, Pasham M, Skillern W, Legant WR, Liu TL, Findlay G, Marino E, Danuser G, Megason S, Betzig E, Kirchhausen T. Membrane dynamics of dividing cells imaged by lattice light-sheet microscopy. Mol Biol Cell 2016; 27:3418-3435. [PMID: 27535432 PMCID: PMC5221578 DOI: 10.1091/mbc.e16-03-0164] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 08/03/2016] [Indexed: 12/02/2022] Open
Abstract
Lattice light-sheet microscopy is used to examine two problems in membrane dynamics—molecular events in clathrin-coated pit formation and changes in cell shape during cell division. This methodology sets a new standard for imaging membrane dynamics in single cells and multicellular assemblies. Membrane remodeling is an essential part of transferring components to and from the cell surface and membrane-bound organelles and for changes in cell shape, which are particularly critical during cell division. Earlier analyses, based on classical optical live-cell imaging and mostly restricted by technical necessity to the attached bottom surface, showed persistent formation of endocytic clathrin pits and vesicles during mitosis. Taking advantage of the resolution, speed, and noninvasive illumination of the newly developed lattice light-sheet fluorescence microscope, we reexamined their assembly dynamics over the entire cell surface and found that clathrin pits form at a lower rate during late mitosis. Full-cell imaging measurements of cell surface area and volume throughout the cell cycle of single cells in culture and in zebrafish embryos showed that the total surface increased rapidly during the transition from telophase to cytokinesis, whereas cell volume increased slightly in metaphase and was relatively constant during cytokinesis. These applications demonstrate the advantage of lattice light-sheet microscopy and enable a new standard for imaging membrane dynamics in single cells and multicellular assemblies.
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Affiliation(s)
- François Aguet
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Srigokul Upadhyayula
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Raphaël Gaudin
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Yi-Ying Chou
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Emanuele Cocucci
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Kangmin He
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Bi-Chang Chen
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
| | | | - Mithun Pasham
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Wesley Skillern
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Wesley R Legant
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
| | - Tsung-Li Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
| | - Greg Findlay
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Eric Marino
- Department of Cell Biology, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
| | - Gaudenz Danuser
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX 75390
| | - Sean Megason
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115
| | - Eric Betzig
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147
| | - Tom Kirchhausen
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115 .,Departments of Cell Biology and Pediatrics, Harvard Medical School, and Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115
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46
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Clathrin-coat disassembly illuminates the mechanisms of Hsp70 force generation. Nat Struct Mol Biol 2016; 23:821-9. [PMID: 27478930 PMCID: PMC5016234 DOI: 10.1038/nsmb.3272] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 07/06/2016] [Indexed: 01/04/2023]
Abstract
Hsp70s use ATP hydrolysis to disrupt protein:protein associations or move macromolecules. One example is Hsc70-mediated disassembly of clathrin coats that form on vesicles during endocytosis. We exploit the exceptional features of these coats to test three models—Brownian ratchet, power-stroke and entropic pulling—proposed to explain how Hsp70s transform their substrates. Our data rule out the ratchet and power-stroke models, and instead support a collision pressure mechanism whereby collisions between clathrin coat walls and Hsc70s drive coats apart. Collision pressure is the complement to the pulling force described in the entropic pulling model. We also find that self-association can augment collision pressure to allow disassembly of clathrin lattices predicted to resist disassembly. These results illuminate how Hsp70s generate the forces that transform their substrates.
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47
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Zumthor JP, Cernikova L, Rout S, Kaech A, Faso C, Hehl AB. Static Clathrin Assemblies at the Peripheral Vacuole-Plasma Membrane Interface of the Parasitic Protozoan Giardia lamblia. PLoS Pathog 2016; 12:e1005756. [PMID: 27438602 PMCID: PMC4954726 DOI: 10.1371/journal.ppat.1005756] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 06/18/2016] [Indexed: 11/19/2022] Open
Abstract
Giardia lamblia is a parasitic protozoan that infects a wide range of vertebrate hosts including humans. Trophozoites are non-invasive but associate tightly with the enterocyte surface of the small intestine. This narrow ecological specialization entailed extensive morphological and functional adaptations during host-parasite co-evolution, including a distinctly polarized array of endocytic organelles termed peripheral vacuoles (PVs), which are confined to the dorsal cortical region exposed to the gut lumen and are in close proximity to the plasma membrane (PM). Here, we investigated the molecular consequences of these adaptations on the Giardia endocytic machinery and membrane coat complexes. Despite the absence of canonical clathrin coated vesicles in electron microscopy, Giardia possesses conserved PV-associated clathrin heavy chain (GlCHC), dynamin-related protein (GlDRP), and assembly polypeptide complex 2 (AP2) subunits, suggesting a novel function for GlCHC and its adaptors. We found that, in contrast to GFP-tagged AP2 subunits and DRP, CHC::GFP reporters have no detectable turnover in living cells, indicating fundamental differences in recruitment to the membrane and disassembly compared to previously characterized clathrin coats. Histochemical localization in electron tomography showed that these long-lived GlCHC assemblies localized at distinctive approximations between the plasma and PV membrane. A detailed protein interactome of GlCHC revealed all of the conserved factors in addition to novel or highly diverged proteins, including a putative clathrin light chain and lipid-binding proteins. Taken together, our data provide strong evidence for giardial CHC as a component of highly stable assemblies at PV-PM junctions that likely have a central role in organizing continuities between the PM and PV membranes for controlled sampling of the fluid environment. This suggests a novel function for CHC in Giardia and the extent of molecular remodeling of endocytosis in this species. In canonical clathrin mediated endocytosis (CME) models, the concerted action of ca. 50 proteins mediates the uptake of extracellular components. The key player in this process is clathrin which coats transport intermediates called clathrin coated vesicles (CCV). The intestinal parasite Giardia lamblia has undergone extensive remodeling during colonization of the mammalian duodenum. Here, we report on unique features of this parasite’s endocytic system, consisting of fixed peripheral vacuoles (PV) in close proximity to the exposed plasma membrane (PM), with no discernible CCVs. Using state-of-the-art imaging strategies, we show that the surface of Giardia trophozoites is pock-marked with PM invaginations reaching to the underlying PV membrane. Co-immunoprecipitation and analysis of protein dynamics reveal that, in line with the absence of CCVs, giardial clathrin assemblies have no dynamic behavior. CHC still remains associated to AP2 and dynamin, both conserved dynamic CME components, and to a newly identified putative clathrin light chain. The emerging model calls for giardial clathrin organized into static cores surrounded by dynamic interaction partners, and most likely involved in the regulation of fusion between the PM and the PVs in a “kiss-and-flush”-like mechanism. This suggests that Giardia harbors a conceptually novel function for clathrin in endocytosis, which might be a consequence of host-parasite co-evolution.
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Affiliation(s)
| | - Lenka Cernikova
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Samuel Rout
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Andres Kaech
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
| | - Carmen Faso
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
- * E-mail: (CF); (ABH)
| | - Adrian B. Hehl
- Institute of Parasitology, University of Zurich, Zurich, Switzerland
- * E-mail: (CF); (ABH)
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48
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Sousa R, Lafer EM. The role of molecular chaperones in clathrin mediated vesicular trafficking. Front Mol Biosci 2015; 2:26. [PMID: 26042225 PMCID: PMC4436892 DOI: 10.3389/fmolb.2015.00026] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 05/05/2015] [Indexed: 12/04/2022] Open
Abstract
The discovery that the 70 kD “uncoating ATPase,” which removes clathrin coats from vesicles after endocytosis, is the constitutively expressed Hsc70 chaperone was a surprise. Subsequent work, however, revealed that uncoating is an archetypal Hsp70 reaction: the cochaperone auxilin, which contains a clathrin binding domain and an Hsc70 binding J domain, recruits Hsc70*ATP to the coat and, concomitant with ATP hydrolysis, transfers it to a hydrophobic Hsc70-binding element found on a flexible tail at the C-terminus of the clathrin heavy chain. Release of clathrin in association with Hsc70*ADP follows, and the subsequent, persistent association of clathrin with Hsc70 is important to prevent aberrant clathrin polymerization. Thus, the two canonical functions of Hsp70—dissociation of existing protein complexes or aggregates, and binding to a protein to inhibit its inappropriate aggregation—are recapitulated in uncoating. Association of clathrin with Hsc70 in vivo is regulated by Hsp110, an Hsp70 NEF that is itself a member of the Hsp70 family. How Hsp110 activity is itself regulated to make Hsc70-free clathrin available for endocytosis is unclear, though at synapses it's possible that the influx of calcium that accompanies depolarization activates the Ca++/calmodulin dependent calcineurin phosphatase which then dephosphorylates and activates Hsp110 to stimulate ADP/ATP exchange and release clathrin from Hsc70*ADP:clathrin complexes.
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Affiliation(s)
- Rui Sousa
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
| | - Eileen M Lafer
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio San Antonio, TX, USA
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49
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Holkar SS, Kamerkar SC, Pucadyil TJ. Spatial Control of Epsin-induced Clathrin Assembly by Membrane Curvature. J Biol Chem 2015; 290:14267-76. [PMID: 25837255 PMCID: PMC4505496 DOI: 10.1074/jbc.m115.653394] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Indexed: 11/21/2022] Open
Abstract
Epsins belong to the family of highly conserved clathrin-associated sorting proteins that are indispensable for clathrin-mediated endocytosis, but their precise functions remain unclear. We have developed an assay system of budded supported membrane tubes displaying planar and highly curved membrane surfaces to analyze intrinsic membrane curvature preference shown by clathrin-associated sorting proteins. Using real-time fluorescence microscopy, we find that epsin preferentially partitions to and assembles clathrin on highly curved membrane surfaces. Sorting of epsin to regions of high curvature strictly depends on binding to phosphatidylinositol 4,5-bisphosphate. Fluorescently labeled clathrins rapidly assemble as foci, which in turn cluster epsin, while maintaining tube integrity. Clathrin foci grow in intensity with a typical time constant of ∼75 s, similar to the time scales for coated pit formation seen in cells. Epsin therefore effectively senses membrane curvature to spatially control clathrin assembly. Our results highlight the potential role of membrane curvature in orchestrating the myriad molecular interactions necessary for the success of clathrin-mediated membrane budding.
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Affiliation(s)
- Sachin S Holkar
- From the Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, India
| | - Sukrut C Kamerkar
- From the Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, India
| | - Thomas J Pucadyil
- From the Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pashan, Pune 411 008, India
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50
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Au CE, Hermo L, Byrne E, Smirle J, Fazel A, Simon PHG, Kearney RE, Cameron PH, Smith CE, Vali H, Fernandez-Rodriguez J, Ma K, Nilsson T, Bergeron JJM. Expression, sorting, and segregation of Golgi proteins during germ cell differentiation in the testis. Mol Biol Cell 2015; 26:4015-32. [PMID: 25808494 PMCID: PMC4710233 DOI: 10.1091/mbc.e14-12-1632] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/19/2015] [Indexed: 12/14/2022] Open
Abstract
A total of 1318 proteins characterized in the male germ cell Golgi apparatus reveal a new germ cell–specific Golgi marker and a new pan-Golgi marker for all cells. The localization of these and other Golgi proteins reveals differential expression linked to mitosis, meiosis, acrosome formation, and postacrosome Golgi migration and destination in the late spermatid. The molecular basis of changes in structure, cellular location, and function of the Golgi apparatus during male germ cell differentiation is unknown. To deduce cognate Golgi proteins, we isolated germ cell Golgi fractions, and 1318 proteins were characterized, with 20 localized in situ. The most abundant protein, GL54D of unknown function, is characterized as a germ cell–specific Golgi-localized type II integral membrane glycoprotein. TM9SF3, also of unknown function, was revealed to be a universal Golgi marker for both somatic and germ cells. During acrosome formation, several Golgi proteins (GBF1, GPP34, GRASP55) localize to both the acrosome and Golgi, while GL54D, TM9SF3, and the Golgi trafficking protein TMED7/p27 are segregated from the acrosome. After acrosome formation, GL54D, TM9SF3, TMED4/p25, and TMED7/p27 continue to mark Golgi identity as it migrates away from the acrosome, while the others (GBF1, GPP34, GRASP55) remain in the acrosome and are progressively lost in later steps of differentiation. Cytoplasmic HSP70.2 and the endoplasmic reticulum luminal protein-folding enzyme PDILT are also Golgi recruited but only during acrosome formation. This resource identifies abundant Golgi proteins that are expressed differentially during mitosis, meiosis, and postacrosome Golgi migration, including the last step of differentiation.
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Affiliation(s)
- Catherine E Au
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Louis Hermo
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Elliot Byrne
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Jeffrey Smirle
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Ali Fazel
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Paul H G Simon
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Robert E Kearney
- Department of Biomedical Engineering Department, McGill University, Montreal, QC H3A 2B4, Canada
| | - Pamela H Cameron
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Charles E Smith
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Hojatollah Vali
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Julia Fernandez-Rodriguez
- Centre for Cellular Imaging, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Kewei Ma
- Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Tommy Nilsson
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - John J M Bergeron
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
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