1
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Kodera S, Kimura T, Nishioka T, Kaneko YK, Yamaguchi M, Kaibuchi K, Ishikawa T. GDP-bound Rab27a regulates clathrin disassembly through HSPA8 after insulin secretion. Arch Biochem Biophys 2023; 749:109789. [PMID: 37852426 DOI: 10.1016/j.abb.2023.109789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 10/12/2023] [Accepted: 10/15/2023] [Indexed: 10/20/2023]
Abstract
Clathrin-dependent endocytosis is a key process for secretory cells, in which molecules on the plasma membrane are both degraded and recycled in a stimulus-dependent manner. There are many reports showing that disruption of endocytosis is involved in the onset of various diseases. Recently, it has been reported that such disruption in pancreatic β-cells causes impaired insulin secretion and might be associated with the pathology of diabetes mellitus. Compared with exocytosis, there are few reports on the molecular mechanism of endocytosis in pancreatic β-cells. We previously reported that GDP-bound Rab27a regulates endocytosis through its GDP-dependent effectors after insulin secretion. In this study, we identified heat shock protein family A member 8 (HSPA8) as a novel interacting protein for GDP-bound Rab27a. HSPA8 directly bound GDP-bound Rab27a via the β2 region of its substrate binding domain (SBD). The β2 fragment was capable of inhibiting the interaction between HSPA8 and GDP-bound Rab27a, and suppressed glucose-induced clathrin-dependent endocytosis in pancreatic β-cells. The region also affected clathrin dynamics on purified clathrin-coated vesicles (CCVs). These results suggest that the interaction between GDP-bound Rab27a and HSPA8 regulates clathrin disassembly from CCVs and subsequent vesicle transport. The regulatory stages in endocytosis by HSPA8 differ from those for other GDP-bound Rab27a effectors. This study shows that GDP-bound Rab27a dominantly regulates each stage in glucose-induced endocytosis through its specific effectors in pancreatic β-cells.
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Affiliation(s)
- Soshiro Kodera
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka, 422-8526, Japan
| | - Toshihide Kimura
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka, 422-8526, Japan.
| | - Tomoki Nishioka
- Division of Cell Biology, International Center for Brain Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake City, Aichi, 470-1192, Japan
| | - Yukiko K Kaneko
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka, 422-8526, Japan
| | - Momoka Yamaguchi
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka, 422-8526, Japan
| | - Kozo Kaibuchi
- Division of Cell Biology, International Center for Brain Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake City, Aichi, 470-1192, Japan
| | - Tomohisa Ishikawa
- Department of Pharmacology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka City, Shizuoka, 422-8526, Japan
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2
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Wang X, Cui X, Wu J, Bao L, Tan Z, Chen C. Peripheral nerves directly mediate the transneuronal translocation of silver nanomaterials from the gut to central nervous system. SCIENCE ADVANCES 2023; 9:eadg2252. [PMID: 37418525 PMCID: PMC10328400 DOI: 10.1126/sciadv.adg2252] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 06/02/2023] [Indexed: 07/09/2023]
Abstract
The blood circulation is considered the only way for the orally administered nanoparticles to enter the central nervous systems (CNS), whereas non-blood route-mediated nanoparticle translocation between organs is poorly understood. Here, we show that peripheral nerve fibers act as direct conduits for silver nanomaterials (Ag NMs) translocation from the gut to the CNS in both mice and rhesus monkeys. After oral gavage, Ag NMs are significantly enriched in the brain and spinal cord of mice with particle state however do not efficiently enter the blood. Using truncal vagotomy and selective posterior rhizotomy, we unravel that the vagus and spinal nerves mediate the transneuronal translocation of Ag NMs from the gut to the brain and spinal cord, respectively. Single-cell mass cytometry analysis revealed that enterocytes and enteric nerve cells take up significant levels of Ag NMs for subsequent transfer to the connected peripheral nerves. Our findings demonstrate nanoparticle transfer along a previously undocumented gut-CNS axis mediated by peripheral nerves.
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Affiliation(s)
- Xiaoyu Wang
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, Beijing 100190, China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xuejing Cui
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, Beijing 100190, China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China
- The GBA National Institute for Nanotechnology Innovation, Guangzhou 510700, Guangdong, China
| | - Junguang Wu
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, Beijing 100190, China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lin Bao
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, Beijing 100190, China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhiqiang Tan
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Chunying Chen
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety and CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology of China, Beijing 100190, China
- School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China
- The GBA National Institute for Nanotechnology Innovation, Guangzhou 510700, Guangdong, China
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3
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Prichard KL, O'Brien NS, Murcia SR, Baker JR, McCluskey A. Role of Clathrin and Dynamin in Clathrin Mediated Endocytosis/Synaptic Vesicle Recycling and Implications in Neurological Diseases. Front Cell Neurosci 2022; 15:754110. [PMID: 35115907 PMCID: PMC8805674 DOI: 10.3389/fncel.2021.754110] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 12/10/2021] [Indexed: 12/17/2022] Open
Abstract
Endocytosis is a process essential to the health and well-being of cell. It is required for the internalisation and sorting of “cargo”—the macromolecules, proteins, receptors and lipids of cell signalling. Clathrin mediated endocytosis (CME) is one of the key processes required for cellular well-being and signalling pathway activation. CME is key role to the recycling of synaptic vesicles [synaptic vesicle recycling (SVR)] in the brain, it is pivotal to signalling across synapses enabling intracellular communication in the sensory and nervous systems. In this review we provide an overview of the general process of CME with a particular focus on two key proteins: clathrin and dynamin that have a central role to play in ensuing successful completion of CME. We examine these two proteins as they are the two endocytotic proteins for which small molecule inhibitors, often of known mechanism of action, have been identified. Inhibition of CME offers the potential to develop therapeutic interventions into conditions involving defects in CME. This review will discuss the roles and the current scope of inhibitors of clathrin and dynamin, providing an insight into how further developments could affect neurological disease treatments.
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4
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Role of a Heat Shock Transcription Factor and the Major Heat Shock Protein Hsp70 in Memory Formation and Neuroprotection. Cells 2021; 10:cells10071638. [PMID: 34210082 PMCID: PMC8305005 DOI: 10.3390/cells10071638] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/18/2021] [Accepted: 06/25/2021] [Indexed: 12/23/2022] Open
Abstract
Heat shock proteins (Hsps) represent the most evolutionarily ancient, conserved, and universal system for protecting cells and the whole body from various types of stress. Among Hsps, the group of proteins with a molecular weight of 70 kDa (Hsp70) plays a particularly important role. These proteins are molecular chaperones that restore the native conformation of partially denatured proteins after exposure to proteotoxic forms of stress and are critical for the folding and intracellular trafficking of de novo synthesized proteins under normal conditions. Hsp70s are expressed at high levels in the central nervous system (CNS) of various animals and protect neurons from various types of stress, including heat shock, hypoxia, and toxins. Numerous molecular and behavioral studies have indicated that Hsp70s expressed in the CNS are important for memory formation. These proteins contribute to the folding and transport of synaptic proteins, modulate signaling cascades associated with synaptic activation, and participate in mechanisms of neurotransmitter release. In addition, HSF1, a transcription factor that is activated under stress conditions and mediates Hsps transcription, is also involved in the transcription of genes encoding many synaptic proteins, whose levels are increased in neurons under stress and during memory formation. Thus, stress activates the molecular mechanisms of memory formation, thereby allowing animals to better remember and later avoid potentially dangerous stimuli. Finally, Hsp70 has significant protective potential in neurodegenerative diseases. Increasing the level of endogenous Hsp70 synthesis or injecting exogenous Hsp70 reduces neurodegeneration, stimulates neurogenesis, and restores memory in animal models of ischemia and Alzheimer’s disease. These findings allow us to consider recombinant Hsp70 and/or Hsp70 pharmacological inducers as potential drugs for use in the treatment of ischemic injury and neurodegenerative disorders.
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5
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Mayer MP. The Hsp70-Chaperone Machines in Bacteria. Front Mol Biosci 2021; 8:694012. [PMID: 34164436 PMCID: PMC8215388 DOI: 10.3389/fmolb.2021.694012] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 05/20/2021] [Indexed: 12/02/2022] Open
Abstract
The ATP-dependent Hsp70s are evolutionary conserved molecular chaperones that constitute central hubs of the cellular protein quality surveillance network. None of the other main chaperone families (Tig, GroELS, HtpG, IbpA/B, ClpB) have been assigned with a comparable range of functions. Through a multitude of functions Hsp70s are involved in many cellular control circuits for maintaining protein homeostasis and have been recognized as key factors for cell survival. Three mechanistic properties of Hsp70s are the basis for their high versatility. First, Hsp70s bind to short degenerate sequence motifs within their client proteins. Second, Hsp70 chaperones switch in a nucleotide-controlled manner between a state of low affinity for client proteins and a state of high affinity for clients. Third, Hsp70s are targeted to their clients by a large number of cochaperones of the J-domain protein (JDP) family and the lifetime of the Hsp70-client complex is regulated by nucleotide exchange factors (NEF). In this review I will discuss advances in the understanding of the molecular mechanism of the Hsp70 chaperone machinery focusing mostly on the bacterial Hsp70 DnaK and will compare the two other prokaryotic Hsp70s HscA and HscC with DnaK.
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Affiliation(s)
- Matthias P Mayer
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, Heidelberg, Germany
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6
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Zou L, Tian Y, Zhang Z. Dysfunction of Synaptic Vesicle Endocytosis in Parkinson's Disease. Front Integr Neurosci 2021; 15:619160. [PMID: 34093144 PMCID: PMC8172812 DOI: 10.3389/fnint.2021.619160] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 04/28/2021] [Indexed: 11/25/2022] Open
Abstract
Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease. It is a chronic and progressive disorder estimated to affect at least 4 million people worldwide. Although the etiology of PD remains unclear, it has been found that the dysfunction of synaptic vesicle endocytosis (SVE) in neural terminal happens before the loss of dopaminergic neurons. Recently, accumulating evidence reveals that the PD-linked synaptic genes, including DNAJC6, SYNJ1, and SH3GL2, significantly contribute to the disruptions of SVE, which is vital for the pathogenesis of PD. In addition, the proteins encoded by other PD-associated genes such as SNCA, LRRK2, PRKN, and DJ-1 also play key roles in the regulation of SVE. Here we present the facts about SVE-related genes and discussed their potential relevance to the pathogenesis of PD.
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Affiliation(s)
- Li Zou
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Ye Tian
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Zhentao Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
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7
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Harper CB, Smillie KJ. Current molecular approaches to investigate pre-synaptic dysfunction. J Neurochem 2021; 157:107-129. [PMID: 33544872 DOI: 10.1111/jnc.15316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/19/2022]
Abstract
Over the course of the last few decades it has become clear that many neurodevelopmental and neurodegenerative disorders have a synaptic defect, which contributes to pathogenicity. A rise in new techniques, and in particular '-omics'-based methods providing large datasets, has led to an increase in potential proteins and pathways implicated in synaptic function and related disorders. Additionally, advancements in imaging techniques have led to the recent discovery of alternative modes of synaptic vesicle recycling. This has resulted in a lack of clarity over the precise role of different pathways in maintaining synaptic function and whether these new pathways are dysfunctional in neurodevelopmental and neurodegenerative disorders. A greater understanding of the molecular detail of pre-synaptic function in health and disease is key to targeting new proteins and pathways for novel treatments and the variety of new techniques currently available provides an ideal opportunity to investigate these functions. This review focuses on techniques to interrogate pre-synaptic function, concentrating mainly on synaptic vesicle recycling. It further examines techniques to determine the underlying molecular mechanism of pre-synaptic dysfunction and discusses methods to identify molecular targets, along with protein-protein interactions and cellular localization. In combination, these techniques will provide an expanding and more complete picture of pre-synaptic function. With the application of recent technological advances, we are able to resolve events with higher spatial and temporal resolution, leading research towards a greater understanding of dysfunction at the presynapse and the role it plays in pathogenicity.
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Affiliation(s)
- Callista B Harper
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
| | - Karen J Smillie
- Centre for Discovery Brain Sciences, University of Edinburgh, Scotland, UK
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8
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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: 25] [Impact Index Per Article: 6.3] [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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9
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The Synaptic Vesicle Cycle Revisited: New Insights into the Modes and Mechanisms. J Neurosci 2020; 39:8209-8216. [PMID: 31619489 DOI: 10.1523/jneurosci.1158-19.2019] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 07/31/2019] [Accepted: 08/03/2019] [Indexed: 02/01/2023] Open
Abstract
Neurotransmission is sustained by endocytosis and refilling of synaptic vesicles (SVs) locally within the presynapse. Until recently, a consensus formed that after exocytosis, SVs are recovered by either fusion pore closure (kiss-and-run) or clathrin-mediated endocytosis directly from the plasma membrane. However, recent data have revealed that SV formation is more complex than previously envisaged. For example, two additional recycling pathways have been discovered, ultrafast endocytosis and activity-dependent bulk endocytosis, in which SVs are regenerated from the internalized membrane and synaptic endosomes. Furthermore, these diverse modes of endocytosis appear to influence both the molecular composition and subsequent physiological role of individual SVs. In addition, previously unknown complexity in SV refilling and reclustering has been revealed. This review presents a modern view of the SV life cycle and discusses how neuronal subtype, physiological temperature, and individual activity patterns can recruit different endocytic modes to generate new SVs and sculpt subsequent presynaptic performance.
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10
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Joshi N, Raveendran A, Nagotu S. Chaperones and Proteostasis: Role in Parkinson's Disease. Diseases 2020; 8:diseases8020024. [PMID: 32580484 PMCID: PMC7349525 DOI: 10.3390/diseases8020024] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 02/07/2023] Open
Abstract
Proper folding to attain a defined three-dimensional structure is a prerequisite for the functionality of a protein. Improper folding that eventually leads to formation of protein aggregates is a hallmark of several neurodegenerative disorders. Loss of protein homeostasis triggered by cellular stress conditions is a major contributing factor for the formation of these toxic aggregates. A conserved class of proteins called chaperones and co-chaperones is implicated in maintaining the cellular protein homeostasis. Expanding the body of evidence highlights the role of chaperones as central mediators in the formation, de-aggregation and degradation of the aggregates. Altered expression and function of chaperones is associated with many neurodegenerative diseases including Parkinson’s disease. Several studies indicate that chaperones are at the center of the cause and effect cycle of this disease. An overview of the various chaperones that are associated with homeostasis of Parkinson’s disease-related proteins and their role in pathogenicity will be discussed in this review.
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11
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Hsc70 Ameliorates the Vesicle Recycling Defects Caused by Excess α-Synuclein at Synapses. eNeuro 2020; 7:ENEURO.0448-19.2020. [PMID: 31941659 PMCID: PMC7031854 DOI: 10.1523/eneuro.0448-19.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/17/2019] [Accepted: 01/03/2020] [Indexed: 02/06/2023] Open
Abstract
α-Synuclein overexpression and aggregation are linked to Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and several other neurodegenerative disorders. In addition to effects in the cell body, α-synuclein accumulation occurs at presynapses where the protein is normally localized. While it is generally agreed that excess α-synuclein impairs synaptic vesicle trafficking, the underlying mechanisms are unknown. α-Synuclein overexpression and aggregation are linked to Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and several other neurodegenerative disorders. In addition to effects in the cell body, α-synuclein accumulation occurs at presynapses where the protein is normally localized. While it is generally agreed that excess α-synuclein impairs synaptic vesicle trafficking, the underlying mechanisms are unknown. We show here that acute introduction of excess human α-synuclein at a classic vertebrate synapse, the lamprey reticulospinal (RS) synapse, selectively impaired the uncoating of clathrin-coated vesicles (CCVs) during synaptic vesicle recycling, leading to an increase in endocytic intermediates and a severe depletion of synaptic vesicles. Furthermore, human α-synuclein and lamprey γ-synuclein both interact in vitro with Hsc70, the chaperone protein that uncoats CCVs at synapses. After introducing excess α-synuclein, Hsc70 availability was reduced at stimulated synapses, suggesting Hsc70 sequestration as a possible mechanism underlying the synaptic vesicle trafficking defects. In support of this hypothesis, increasing the levels of exogenous Hsc70 along with α-synuclein ameliorated the CCV uncoating and vesicle recycling defects. These experiments identify a reduction in Hsc70 availability at synapses, and consequently its function, as the mechanism by which α-synuclein induces synaptic vesicle recycling defects. To our knowledge, this is the first report of a viable chaperone-based strategy for reversing the synaptic vesicle trafficking defects associated with excess α-synuclein, which may be of value for improving synaptic function in PD and other synuclein-linked diseases.
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12
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Törnroth-Horsefield S. Phosphorylation of human AQP2 and its role in trafficking. VITAMINS AND HORMONES 2019; 112:95-117. [PMID: 32061351 DOI: 10.1016/bs.vh.2019.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Human Aquaporin 2 (AQP2) is a membrane-bound water channel found in the kidney collecting duct whose regulation by trafficking plays a key role in regulating urine volume. AQP2 trafficking is tightly controlled by the pituitary hormone arginine vasopressin (AVP), which stimulates translocation of AQP2 residing in storage vesicles to the apical membrane. The AVP-dependent translocation of AQP2 to and from the apical membrane is controlled by multiple phosphorylation sites in the AQP2 C-terminus, the phosphorylation of which alters its affinity to proteins within the cellular membrane protein trafficking machinery. The aim of this chapter is to provide a summary of what is currently known about AVP-mediated AQP2 trafficking, dissecting the roles of individual phosphorylation sites, kinases and phosphatases and interacting proteins. From this, the picture of an immensely complex process emerges, of which many structural and molecular details remains to be elucidated.
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13
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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] [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
Chen et al. reconstitute endocytosis in a cell-free system and show that cargo sorting requires the dynamic dissociation of clathrin during the growth phase of the clathrin-coated pit formation. 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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14
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Roosen DA, Blauwendraat C, Cookson MR, Lewis PA. DNAJC
proteins and pathways to parkinsonism. FEBS J 2019; 286:3080-3094. [DOI: 10.1111/febs.14936] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 03/21/2019] [Accepted: 05/21/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Dorien A. Roosen
- Laboratory of Neurogenetics National Institute on AgingNational Institutes of Health Bethesda MD USA
- School of Pharmacy University of Reading UK
| | - Cornelis Blauwendraat
- Laboratory of Neurogenetics National Institute on AgingNational Institutes of Health Bethesda MD USA
| | - Mark R. Cookson
- Laboratory of Neurogenetics National Institute on AgingNational Institutes of Health Bethesda MD USA
| | - Patrick A. Lewis
- School of Pharmacy University of Reading UK
- Department of Neurodegenerative Disease UCL Institute of Neurology London UK
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15
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A new role of anterograde motor Kif5b in facilitating large clathrin-coated vesicle mediated endocytosis via regulating clathrin uncoating. Cell Discov 2019; 4:65. [PMID: 30603101 PMCID: PMC6305376 DOI: 10.1038/s41421-018-0067-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/11/2018] [Accepted: 10/11/2018] [Indexed: 11/30/2022] Open
Abstract
Kif5b-driven anterograde transport and clathrin-mediated endocytosis (CME) are responsible for opposite intracellular trafficking, contributing to plasma membrane homeostasis. However, whether and how the two trafficking processes coordinate remain unclear. Here, we show that Kif5b directly interacts with clathrin heavy chain (CHC) at a region close to that for uncoating catalyst (Hsc70) and preferentially localizes on relatively large clathrin-coated vesicles (CCVs). Uncoating in vitro is decreased for CCVs from the cortex of kif5b conditional knockout (mutant) mouse and facilitated by adding Kif5b fragments containing CHC-binding site, while cell peripheral distribution of CHC or Hsc70 keeps unaffected by Kif5b depletion. Furthermore, cellular entry of vesicular stomatitis virus that internalizes into large CCV is inhibited by Kif5b depletion or introducing a dominant-negative Kif5b fragment. These findings showed a new role of Kif5b in regulating large CCV-mediated CME via affecting CCV uncoating, indicating Kif5b as a molecular knot connecting anterograde transport to CME.
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To reduce premature drug release while ensuring burst intracellular drug release of solid lipid nanoparticle-based drug delivery system with clathrin modification. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2019; 15:108-118. [DOI: 10.1016/j.nano.2018.05.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/13/2018] [Accepted: 05/20/2018] [Indexed: 12/12/2022]
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17
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Synergy between intrinsically disordered domains and structured proteins amplifies membrane curvature sensing. Nat Commun 2018; 9:4152. [PMID: 30297718 PMCID: PMC6175956 DOI: 10.1038/s41467-018-06532-3] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 09/06/2018] [Indexed: 12/12/2022] Open
Abstract
The ability of proteins to sense membrane curvature is essential to cellular function. All known sensing mechanisms rely on protein domains with specific structural features such as wedge-like amphipathic helices and crescent-shaped BAR domains. Yet many proteins that contain these domains also contain large intrinsically disordered regions. Here we report that disordered domains are themselves potent sensors of membrane curvature. Comparison of Monte Carlo simulations with in vitro and live-cell measurements demonstrates that the polymer-like behavior of disordered domains found in endocytic proteins drives them to partition preferentially to convex membrane surfaces, which place fewer geometric constraints on their conformational entropy. Further, proteins containing both structured curvature sensors and disordered regions are more than twice as curvature sensitive as their respective structured domains alone. These findings demonstrate an entropic mechanism of curvature sensing that is independent of protein structure and illustrate how structured and disordered domains can synergistically enhance curvature sensitivity. Many proteins which sense membrane curvature contain intrinsically disordered domains. Here the authors use Monte Carlo simulations combined with experimental approaches and report that disordered domains are potent sensors of membrane curvature.
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LRRK2 phosphorylation of auxilin mediates synaptic defects in dopaminergic neurons from patients with Parkinson's disease. Proc Natl Acad Sci U S A 2018; 115:5576-5581. [PMID: 29735704 DOI: 10.1073/pnas.1717590115] [Citation(s) in RCA: 104] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Recently identified Parkinson's disease (PD) genes involved in synaptic vesicle endocytosis, such as DNAJC6 (auxilin), have further implicated synaptic dysfunction in PD pathogenesis. However, how synaptic dysfunction contributes to the vulnerability of human dopaminergic neurons has not been previously explored. Here, we demonstrate that commonly mutated, PD-linked leucine-rich repeat kinase 2 (LRRK2) mediates the phosphorylation of auxilin in its clathrin-binding domain at Ser627. Kinase activity-dependent LRRK2 phosphorylation of auxilin led to differential clathrin binding, resulting in disrupted synaptic vesicle endocytosis and decreased synaptic vesicle density in LRRK2 patient-derived dopaminergic neurons. Moreover, impaired synaptic vesicle endocytosis contributed to the accumulation of oxidized dopamine that in turn mediated pathogenic effects such as decreased glucocerebrosidase activity and increased α-synuclein in mutant LRRK2 neurons. Importantly, these pathogenic phenotypes were partially attenuated by restoring auxilin function in mutant LRRK2 dopaminergic neurons. Together, this work suggests that mutant LRRK2 disrupts synaptic vesicle endocytosis, leading to altered dopamine metabolism and dopamine-mediated toxic effects in patient-derived dopaminergic neurons.
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Walsh RB, Bloom OE, Morgan JR. Acute Manipulations of Clathrin-Mediated Endocytosis at Presynaptic Nerve Terminals. Methods Mol Biol 2018; 1847:65-82. [PMID: 30129010 DOI: 10.1007/978-1-4939-8719-1_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Acute perturbations of clathrin and associated proteins at synapses have provided a wealth of knowledge on the molecular mechanisms underlying clathrin-mediated endocytosis (CME). The basic approach entails presynaptic microinjection of an inhibitory reagent targeted to the CME pathway, followed by a detailed ultrastructural analysis to identify how the perturbation affects the number and distribution of synaptic vesicles, plasma membrane, clathrin-coated pits, and clathrin-coated vesicles. This chapter describes the methodology for acutely perturbing CME at the lamprey giant reticulospinal synapse, a model vertebrate synapse that has been instrumental for identifying key protein-protein interactions that regulate CME in presynaptic nerve terminals with broader extension to nonneuronal cell types.
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Affiliation(s)
- Rylie B Walsh
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, USA
| | - Ona E Bloom
- Department of Physical Medicine, The Hofstra North Shore-LIJ School of Medicine, The Feinstein Institute for Medical Research, Manhasset, NY, USA.,Department of Rehabilitation, The Hofstra North Shore-LIJ School of Medicine, The Feinstein Institute for Medical Research, Manhasset, NY, USA
| | - Jennifer R Morgan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, USA.
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20
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Medeiros AT, Soll LG, Tessari I, Bubacco L, Morgan JR. α-Synuclein Dimers Impair Vesicle Fission during Clathrin-Mediated Synaptic Vesicle Recycling. Front Cell Neurosci 2017; 11:388. [PMID: 29321725 PMCID: PMC5732215 DOI: 10.3389/fncel.2017.00388] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/22/2017] [Indexed: 11/16/2022] Open
Abstract
α-Synuclein is a presynaptic protein that regulates synaptic vesicle (SV) trafficking. In Parkinson’s disease (PD) and several other neurodegenerative disorders, aberrant oligomerization and aggregation of α-synuclein lead to synaptic dysfunction and neurotoxicity. Despite evidence that α-synuclein oligomers are generated within neurons under physiological conditions, and that altering the balance of monomers and oligomers contributes to disease pathogenesis, how each molecular species of α-synuclein impacts SV trafficking is currently unknown. To address this, we have taken advantage of lamprey giant reticulospinal (RS) synapses, which are accessible to acute perturbations via axonal microinjection of recombinant proteins. We previously reported that acute introduction of monomeric α-synuclein inhibited SV recycling, including effects on the clathrin pathway. Here, we report the effects of α-synuclein dimers at synapses. Similar to monomeric α-synuclein, both recombinant α-synuclein dimers that were evaluated bound to small liposomes containing anionic lipids in vitro, but with reduced efficacy. When introduced to synapses, the α-synuclein dimers also induced SV recycling defects, which included a build up of clathrin-coated pits (CCPs) with constricted necks that were still attached to the plasma membrane, a phenotype indicative of a vesicle fission defect. Interestingly, both α-synuclein dimers induced longer necks on CCPs as well as complex, branching membrane tubules, which were distinct from the CCPs induced by a dynamin inhibitor, Dynasore. In contrast, monomeric α-synuclein induced a buildup of free clathrin-coated vesicles (CCVs), indicating an inhibition of clathrin-mediated endocytosis at a later stage during the clathrin uncoating process. Taken together, these data further support the conclusion that excess α-synuclein impairs SV recycling. The data additionally reveal that monomeric and dimeric α-synuclein produce distinct effects on clathrin-mediated endocytosis, predicting different molecular mechanisms. Understanding what these mechanisms are could help to further elucidate the normal functions of this protein, as well as the mechanisms underlying PD pathologies.
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Affiliation(s)
- Audrey T Medeiros
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | - Lindsey G Soll
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
| | | | - Luigi Bubacco
- Department of Biology, University of Padova, Padova, Italy
| | - Jennifer R Morgan
- The Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, MA, United States
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21
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RNAi-Mediated Reverse Genetic Screen Identified Drosophila Chaperones Regulating Eye and Neuromuscular Junction Morphology. G3-GENES GENOMES GENETICS 2017; 7:2023-2038. [PMID: 28500055 PMCID: PMC5499113 DOI: 10.1534/g3.117.041632] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Accumulation of toxic proteins in neurons has been linked with the onset of neurodegenerative diseases, which in many cases are characterized by altered neuronal function and synapse loss. Molecular chaperones help protein folding and the resolubilization of unfolded proteins, thereby reducing the protein aggregation stress. While most of the chaperones are expressed in neurons, their functional relevance remains largely unknown. Here, using bioinformatics analysis, we identified 95 Drosophila chaperones and classified them into seven different classes. Ubiquitous actin5C-Gal4-mediated RNAi knockdown revealed that ∼50% of the chaperones are essential in Drosophila Knocking down these genes in eyes revealed that ∼30% of the essential chaperones are crucial for eye development. Using neuron-specific knockdown, immunocytochemistry, and robust behavioral assays, we identified a new set of chaperones that play critical roles in the regulation of Drosophila NMJ structural organization. Together, our data present the first classification and comprehensive analysis of Drosophila chaperones. Our screen identified a new set of chaperones that regulate eye and NMJ morphogenesis. The outcome of the screen reported here provides a useful resource for further elucidating the role of individual chaperones in Drosophila eye morphogenesis and synaptic development.
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22
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Yagi H, Takabayashi T, Xie MJ, Kuroda K, Sato M. Subcellular distribution of non-muscle myosin IIb is controlled by FILIP through Hsc70. PLoS One 2017; 12:e0172257. [PMID: 28234934 PMCID: PMC5325215 DOI: 10.1371/journal.pone.0172257] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 02/02/2017] [Indexed: 12/11/2022] Open
Abstract
The neuronal spine is a small, actin-rich dendritic or somatic protrusion that serves as the postsynaptic compartment of the excitatory synapse. The morphology of the spine reflects the activity of the synapse and is regulated by the dynamics of the actin cytoskeleton inside, which is controlled by actin binding proteins such as non-muscle myosin. Previously, we demonstrated that the subcellular localization and function of myosin IIb are regulated by its binding partner, filamin-A interacting protein (FILIP). However, how the subcellular distribution of myosin IIb is controlled by FILIP is not yet known. The objective of this study was to identify potential binding partners of FILIP that contribute to its regulation of non-muscle myosin IIb. Pull-down assays detected a 70-kDa protein that was identified by mass spectrometry to be the chaperone protein Hsc70. The binding of Hsc70 to FILIP was controlled by the adenosine triphosphatase (ATPase) activity of Hsc70. Further, FILIP bound to Hsc70 via a domain that was not required for binding non-muscle myosin IIb. Inhibition of ATPase activity of Hsc70 impaired the effect of FILIP on the subcellular distribution of non-muscle myosin IIb. Further, in primary cultured neurons, an inhibitor of Hsc70 impeded the morphological change in spines induced by FILIP. Collectively, these results demonstrate that Hsc70 interacts with FILIP to mediate its effects on non-muscle myosin IIb and to regulate spine morphology.
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Affiliation(s)
- Hideshi Yagi
- Department of Anatomy and Cell Biology, Hyogo College of Medicine, Hyogo, Japan.,Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Tetsuji Takabayashi
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Min-Jue Xie
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.,Research Center for Child Mental Development, University of Fukui, Fukui, Japan
| | - Kazuki Kuroda
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Makoto Sato
- Division of Cell Biology and Neuroscience, Department of Morphological and Physiological Sciences, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.,Research Center for Child Mental Development, University of Fukui, Fukui, Japan.,United Graduate School of Child Development, Osaka University, Kanazawa University, Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka, Japan.,Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka, Japan
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23
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Uytterhoeven V, Lauwers E, Maes I, Miskiewicz K, Melo MN, Swerts J, Kuenen S, Wittocx R, Corthout N, Marrink SJ, Munck S, Verstreken P. Hsc70-4 Deforms Membranes to Promote Synaptic Protein Turnover by Endosomal Microautophagy. Neuron 2016; 88:735-48. [PMID: 26590345 DOI: 10.1016/j.neuron.2015.10.012] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 09/10/2015] [Accepted: 09/28/2015] [Indexed: 11/26/2022]
Abstract
Synapses are often far from their cell bodies and must largely independently cope with dysfunctional proteins resulting from synaptic activity and stress. To identify membrane-associated machines that can engulf synaptic targets destined for degradation, we performed a large-scale in vitro liposome-based screen followed by functional studies. We identified a presynaptically enriched chaperone Hsc70-4 that bends membranes based on its ability to oligomerize. This activity promotes endosomal microautophagy and the turnover of specific synaptic proteins. Loss of microautophagy slows down neurotransmission while gain of microautophagy increases neurotransmission. Interestingly, Sgt, a cochaperone of Hsc70-4, is able to switch the activity of Hsc70-4 from synaptic endosomal microautophagy toward chaperone activity. Hence, Hsc70-4 controls rejuvenation of the synaptic protein pool in a dual way: either by refolding proteins together with Sgt, or by targeting them for degradation by facilitating endosomal microautophagy based on its membrane deforming activity.
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Affiliation(s)
- Valerie Uytterhoeven
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Elsa Lauwers
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium.
| | - Ine Maes
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Katarzyna Miskiewicz
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Manuel N Melo
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Jef Swerts
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Sabine Kuenen
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Rafaël Wittocx
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium
| | - Nikky Corthout
- VIB Bio-Imaging Core Facility, Herestraat 49, 3000 Leuven, Belgium
| | - Siewert-Jan Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Sebastian Munck
- VIB Bio-Imaging Core Facility, Herestraat 49, 3000 Leuven, Belgium
| | - Patrik Verstreken
- KU Leuven, Center for Human Genetics, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium; VIB Center for the Biology of Disease, Leuven Institute for Neurodegenerative Disease (LIND), Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium.
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24
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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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25
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Yang T, Li XN, Li XG, Li M, Gao PZ. DNAJC6 promotes hepatocellular carcinoma progression through induction of epithelial-mesenchymal transition. Biochem Biophys Res Commun 2014; 455:298-304. [PMID: 25446072 DOI: 10.1016/j.bbrc.2014.11.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 11/06/2014] [Indexed: 01/13/2023]
Abstract
Epithelial-mesenchymal transition (EMT) is a developmental program, which is associated with hepatocellular carcinoma (HCC) development and progression. DNAJC6 (DNA/HSP40 homolog subfamily C member 6) encodes auxilin, which is responsible for juvenile Parkinsonism with phenotypic variability. However, the role of DNAJC6 in HCC development and progression is limited. Here, we report that DNAJC6 is up-regulated in HCC tissues and up-regulation of DNAJC6 expression predicts poor outcome in patients with HCC. Furthermore, overexpression of DNAJC6 enhances the ability for acquisition of mesenchymal traits, enhanced cell proliferation and invasion. DNAJC6 positively regulated expression of EMT-related transcription factor, also activating transforming growth factor β (TGF-β) pathway to contribute to EMT. Our findings demonstrated an important function of DNAJC6 in the progression of HCC by induction of EMT, and they implicate DNAJC6 as a marker of poor outcome in HCC.
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Affiliation(s)
- Tao Yang
- Hepatobiliary Surgery, The First Hospital of Shijiazhuang City, Shijiazhuang 050011, China
| | - Xiao-Na Li
- General Surgery, Sports Science Institute of Hebei Province, Shijiazhuang 050011, China
| | - Xing-Guang Li
- General Surgery, The First Hospital of Shijiazhuang City, Shijiazhuang 050011, China
| | - Ming Li
- General Surgery, The First Hospital of Shijiazhuang City, Shijiazhuang 050011, China
| | - Peng-Zhi Gao
- Hepatobiliary Surgery, The First Hospital of Shijiazhuang City, Shijiazhuang 050011, China.
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26
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Koutras C, Braun JEA. J protein mutations and resulting proteostasis collapse. Front Cell Neurosci 2014; 8:191. [PMID: 25071450 PMCID: PMC4086201 DOI: 10.3389/fncel.2014.00191] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 06/21/2014] [Indexed: 01/20/2023] Open
Abstract
Despite a century of intensive investigation the effective treatment of protein aggregation diseases remains elusive. Ordinarily, molecular chaperones ensure that proteins maintain their functional conformation. The appearance of misfolded proteins that aggregate implies the collapse of the cellular chaperone quality control network. That said, the cellular chaperone network is extensive and functional information regarding the detailed action of specific chaperones is not yet available. J proteins (DnaJ/Hsp40) are a family of chaperone cofactors that harness Hsc70 (heat shock cognate protein of 70 kDa) for diverse conformational cellular tasks and, as such, represent novel clinically relevant targets for diseases resulting from the disruption of proteostasis. Here we review incisive reports identifying mutations in individual J protein chaperones and the proteostasis collapse that ensues.
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Affiliation(s)
- Carolina Koutras
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of CalgaryCalgary, AB, Canada
| | - Janice E. A. Braun
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, University of CalgaryCalgary, AB, Canada
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27
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Chanoux RA, Shubin CB, Robay A, Suaud L, Rubenstein RC. Hsc70 negatively regulates epithelial sodium channel trafficking at multiple sites in epithelial cells. Am J Physiol Cell Physiol 2013; 305:C776-87. [PMID: 23885065 DOI: 10.1152/ajpcell.00059.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The epithelial sodium channel (ENaC) plays an important role in homeostasis of blood pressure and of the airway surface liquid, and excess function of ENaC results in refractory hypertension (in Liddle's syndrome) and impaired mucociliary clearance (in cystic fibrosis). The regulation of ENaC by molecular chaperones, such as the 70-kDa heat shock protein Hsc70, is not completely understood. Our previously published data suggest that Hsc70 negatively affects ENaC activity and surface expression in Xenopus oocytes; here we investigate the mechanism by which Hsc70 acts on ENaC in epithelial cells. In Madin-Darby canine kidney cells stably expressing epitope-tagged αβγ-ENaC and with tetracycline-inducible overexpression of Hsc70, treatment with 5 μg/ml doxycycline increased total Hsc70 expression 20%. This increase in Hsc70 expression led to a decrease in ENaC activity and surface expression that corresponded to an increased rate of functional ENaC retrieval from the cell surface. In addition, Hsc70 overexpression decreased the association of newly synthesized ENaC subunits. These data support the hypothesis that Hsc70 inhibits ENaC functional expression at the apical surface of epithelia by regulating ENaC biogenesis and ENaC trafficking at the cell surface.
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Affiliation(s)
- Rebecca A Chanoux
- Division of Pulmonary Medicine and Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; and
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28
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Ahn KH, Kim SK, Choi JM, Jung SY, Won JH, Back MJ, Fu Z, Jang JM, Ha HC, Kim DK. Identification of Heat Shock Protein 60 as a Regulator of Neutral Sphingomyelinase 2 and Its Role in Dopamine Uptake. PLoS One 2013; 8:e67216. [PMID: 23840630 PMCID: PMC3686747 DOI: 10.1371/journal.pone.0067216] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 05/21/2013] [Indexed: 11/18/2022] Open
Abstract
Activation of sphingomyelinase (SMase) by extracellular stimuli is the major pathway for cellular production of ceramide, a bioactive lipid mediator acting through sphingomyelin (SM) hydrolysis. Previously, we reported the existence of six forms of neutral pH–optimum and Mg2+-dependent SMase (N-SMase) in the membrane fractions of bovine brain. Here, we focus on N-SMase ε from salt-extracted membranes. After extensive purification by 12,780-fold with a yield of 1.3%, this enzyme was eventually characterized as N-SMase2. The major single band of 60-kDa molecular mass in the active fractions of the final purification step was identified as heat shock protein 60 (Hsp60) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis. Proximity ligation assay and immunoprecipitation study showed that Hsp60 interacted with N-SMase2, prompting us to examine the effect of Hsp60 on N-SMase2 and ceramide production. Interestingly, Hsp60 siRNA treatment significantly increased the protein level of N-SMase2 in N-SMase2-overexpressed HEK293 cells. Furthermore, transfection of Hsp60 siRNA into PC12 cells effectively increased both N-SMase activity and ceramide production and increased dopamine re-uptake with paralleled increase. Taken together, these results show that Hsp60 may serve as a negative regulator in N-SMase2-induced dopamine re-uptake by decreasing the protein level of N-SMase2.
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Affiliation(s)
- Kyong-Hoon Ahn
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Seok-Kyun Kim
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Jong-Min Choi
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Sung-Yun Jung
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Jong-Hoon Won
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Moon-Jung Back
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Zhicheng Fu
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Ji-Min Jang
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Hae-Chan Ha
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
| | - Dae-Kyong Kim
- Department of Environmental & Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjak-Ku, Seoul, South Korea
- * E-mail:
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Gillingwater TH, Wishart TM. Mechanisms underlying synaptic vulnerability and degeneration in neurodegenerative disease. Neuropathol Appl Neurobiol 2013; 39:320-34. [PMID: 23289367 DOI: 10.1111/nan.12014] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 12/21/2012] [Indexed: 02/06/2023]
Abstract
Recent developments in our understanding of events underlying neurodegeneration across the central and peripheral nervous systems have highlighted the critical role that synapses play in the initiation and progression of neuronal loss. With the development of increasingly accurate and versatile animal models of neurodegenerative disease it has become apparent that disruption of synaptic form and function occurs comparatively early, preceding the onset of degenerative changes in the neuronal cell body. Yet, despite our increasing awareness of the importance of synapses in neurodegeneration, the mechanisms governing the particular susceptibility of distal neuronal processes are only now becoming clear. In this review we bring together recent developments in our understanding of cellular and molecular mechanisms regulating synaptic vulnerability. We have placed a particular focus on three major areas of research that have gained significant interest over the last few years: (i) the contribution of synaptic mitochondria to neurodegeneration; (ii) the contribution of pathways that modulate synaptic function; and (iii) regulation of synaptic degeneration by local posttranslational modifications such as ubiquitination. We suggest that targeting these organelles and pathways may be a productive way to develop synaptoprotective strategies applicable to a range of neurodegenerative conditions.
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Affiliation(s)
- T H Gillingwater
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK
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Morgan JR, Jiang J, Oliphint PA, Jin S, Gimenez LE, Busch DJ, Foldes AE, Zhuo Y, Sousa R, Lafer EM. A role for an Hsp70 nucleotide exchange factor in the regulation of synaptic vesicle endocytosis. J Neurosci 2013; 33:8009-21. [PMID: 23637191 PMCID: PMC3707978 DOI: 10.1523/jneurosci.4505-12.2013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 03/20/2013] [Accepted: 03/29/2013] [Indexed: 12/28/2022] Open
Abstract
Neurotransmission requires a continuously available pool of synaptic vesicles (SVs) that can fuse with the plasma membrane and release their neurotransmitter contents upon stimulation. After fusion, SV membranes and membrane proteins are retrieved from the presynaptic plasma membrane by clathrin-mediated endocytosis. After the internalization of a clathrin-coated vesicle, the vesicle must uncoat to replenish the pool of SVs. Clathrin-coated vesicle uncoating requires ATP and is mediated by the ubiquitous molecular chaperone Hsc70. In vitro, depolymerized clathrin forms a stable complex with Hsc70*ADP. This complex can be dissociated by nucleotide exchange factors (NEFs) that release ADP from Hsc70, allowing ATP to bind and induce disruption of the clathrin:Hsc70 association. Whether NEFs generally play similar roles in vesicle trafficking in vivo and whether they play such roles in SV endocytosis in particular is unknown. To address this question, we used information from recent structural and mechanistic studies of Hsp70:NEF and Hsp70:co-chaperone interactions to design a NEF inhibitor. Using acute perturbations at giant reticulospinal synapses of the sea lamprey (Petromyzon marinus), we found that this NEF inhibitor inhibited SV endocytosis. When this inhibitor was mutated so that it could no longer bind and inhibit Hsp110 (a NEF that we find to be highly abundant in brain cytosol), its ability to inhibit SV endocytosis was eliminated. These observations indicate that the action of a NEF, most likely Hsp110, is normally required during SV trafficking to release clathrin from Hsc70 and make it available for additional rounds of endocytosis.
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Affiliation(s)
- Jennifer R. Morgan
- Eugene Bell Center for Regenerative Biology and Tissue Engineering, Marine Biological Laboratory, Woods Hole, Massachusetts 02543
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712, and
| | - Jianwen Jiang
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78212
| | - Paul A. Oliphint
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712, and
| | - Suping Jin
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78212
| | - Luis E. Gimenez
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78212
| | - David J. Busch
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712, and
| | - Andrea E. Foldes
- Section of Molecular Cell and Developmental Biology, Institute for Cell and Molecular Biology, Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712, and
| | - Yue Zhuo
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78212
| | - Rui Sousa
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78212
| | - Eileen M. Lafer
- Department of Biochemistry and Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78212
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Jin AJ, Lafer EM, Peng JQ, Smith PD, Nossal R. Unraveling protein-protein interactions in clathrin assemblies via atomic force spectroscopy. Methods 2013; 59:316-27. [PMID: 23270814 PMCID: PMC3608793 DOI: 10.1016/j.ymeth.2012.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 12/08/2012] [Accepted: 12/14/2012] [Indexed: 01/14/2023] Open
Abstract
Atomic force microscopy (AFM), single molecule force spectroscopy (SMFS), and single particle force spectroscopy (SPFS) are used to characterize intermolecular interactions and domain structures of clathrin triskelia and clathrin-coated vesicles (CCVs). The latter are involved in receptor-mediated endocytosis (RME) and other trafficking pathways. Here, we subject individual triskelia, bovine-brain CCVs, and reconstituted clathrin-AP180 coats to AFM-SMFS and AFM-SPFS pulling experiments and apply novel analytics to extract force-extension relations from very large data sets. The spectroscopic fingerprints of these samples differ markedly, providing important new information about the mechanism of CCV uncoating. For individual triskelia, SMFS reveals a series of events associated with heavy chain alpha-helix hairpin unfolding, as well as cooperative unraveling of several hairpin domains. SPFS of clathrin assemblies exposes weaker clathrin-clathrin interactions that are indicative of inter-leg association essential for RME and intracellular trafficking. Clathrin-AP180 coats are energetically easier to unravel than the coats of CCVs, with a non-trivial dependence on force-loading rate.
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Affiliation(s)
- Albert J Jin
- Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, DHHS, Bethesda, MD 20892, United States.
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Köroğlu Ç, Baysal L, Cetinkaya M, Karasoy H, Tolun A. DNAJC6 is responsible for juvenile parkinsonism with phenotypic variability. Parkinsonism Relat Disord 2012; 19:320-4. [PMID: 23211418 DOI: 10.1016/j.parkreldis.2012.11.006] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 11/09/2012] [Accepted: 11/12/2012] [Indexed: 12/17/2022]
Abstract
Familial parkinson's disease is both clinically and genetically heterogeneous. By mapping the disease locus with a lod score of 5.13 to a < 3.5 Mbp region at 1p31.3 in a consanguineous family and subsequent exome sequencing analysis, we identified homozygous truncating mutation p.Q734X in DNAJC6. Four members of the family were afflicted with juvenile parkinsonism that presented with mental retardation, pyramidal signs and epilepsy, as well as varying degrees of a progressive neurological disease. Recently a splicing mutation in the same gene was reported in two brothers with juvenile parkinsonism that was not L-Dopa responsive and not accompanied by pyramidal signs or mental retardation. Also, an 80-kb deletion that included DNAJC6 sequences was identified in a boy reported as having obesity, epilepsy and mental retardation but not any signs of parkinsonism. The phenotype of our study family resembles both of those families, which among themselves do not share any clinical features. Our findings further establish DNAJC6 as a juvenile parkinsonism gene, and expand the spectrums of the parkinsonism phenotype and DNAJC6 mutation. DNAJC6 encodes the neuronal co-chaperone auxilin. We found that its transcript is highly significantly more abundant in brain as compared to the non-neural tissues assayed.
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Affiliation(s)
- Çiğdem Köroğlu
- Boğaziçi University, Department of Molecular Biology and Genetics, KP 301, Bebek, 34342 Istanbul, Turkey
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33
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Chanoux RA, Rubenstein RC. Molecular Chaperones as Targets to Circumvent the CFTR Defect in Cystic Fibrosis. Front Pharmacol 2012; 3:137. [PMID: 22822398 PMCID: PMC3398409 DOI: 10.3389/fphar.2012.00137] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 06/25/2012] [Indexed: 01/07/2023] Open
Abstract
Cystic Fibrosis (CF) is the most common autosomal recessive lethal disorder among Caucasian populations. CF results from mutations and resulting dysfunction of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR). CFTR is a cyclic AMP-dependent chloride channel that is localized to the apical membrane in epithelial cells where it plays a key role in salt and water homeostasis. An intricate network of molecular chaperone proteins regulates CFTR’s proper maturation and trafficking to the apical membrane. Understanding and manipulation of this network may lead to therapeutics for CF in cases where mutant CFTR has aberrant trafficking.
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Affiliation(s)
- Rebecca A Chanoux
- Division of Pulmonary Medicine and Cystic Fibrosis Center, The Children's Hospital of Philadelphia Philadelphia, PA, USA
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34
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Synaptic vesicle exocytosis in hippocampal synaptosomes correlates directly with total mitochondrial volume. J Mol Neurosci 2012; 49:223-30. [PMID: 22772899 DOI: 10.1007/s12031-012-9848-8] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 06/22/2012] [Indexed: 10/28/2022]
Abstract
Synaptic plasticity in many regions of the central nervous system leads to the continuous adjustment of synaptic strength, which is essential for learning and memory. In this study, we show by visualizing synaptic vesicle release in mouse hippocampal synaptosomes that presynaptic mitochondria and, specifically, their capacities for ATP production are essential determinants of synaptic vesicle exocytosis and its magnitude. Total internal reflection microscopy of FM1-43 loaded hippocampal synaptosomes showed that inhibition of mitochondrial oxidative phosphorylation reduces evoked synaptic release. This reduction was accompanied by a substantial drop in synaptosomal ATP levels. However, cytosolic calcium influx was not affected. Structural characterization of stimulated hippocampal synaptosomes revealed that higher total presynaptic mitochondrial volumes were consistently associated with higher levels of exocytosis. Thus, synaptic vesicle release is linked to the presynaptic ability to regenerate ATP, which itself is a utility of mitochondrial density and activity.
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35
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Graham ME, Stone RS, Robinson PJ, Payne RJ. Synthesis and protein binding studies of a peptide fragment of clathrin assembly protein AP180 bearing an O-linked β-N-acetylglucosaminyl-6-phosphate modification. Org Biomol Chem 2012; 10:2545-51. [DOI: 10.1039/c2ob07139h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Gade N, Mahapatra RK, Sonawane A, Singh VK, Doreswamy R, Saini M. Molecular Characterization of Heat Shock Protein 70-1 Gene of Goat (Capra hircus). Mol Biol Int 2010; 2010:108429. [PMID: 22110953 PMCID: PMC3218308 DOI: 10.4061/2010/108429] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Accepted: 04/14/2010] [Indexed: 01/24/2023] Open
Abstract
Heat shock protein 70 (HSP 70) plays a vital role by bestowing cytoprotection against diverse kinds of stresses. The ubiquitous HSP 70 proteins are the most abundant and temperature sensitive among all the HSPs. The present paper has characterized HSP70-1 cDNA in goat (Capra hircus). Total RNA isolated from goat peripheral blood mononuclear cells was reverse transcribed to cDNA that was used for amplification of HSP 70-1 gene. PCR product (1926 bp) was cloned in pGEM-T easy vector and sequenced. Sequence analysis revealed 1926-bp-long open reading frame of HSP 70-1 gene encoding 641 amino acids in goat, as reported in cattle. At nucleotide level, goat HSP 70-1 was found to be 96-99% similar to that of sheep (partial), cattle, and buffalo whereas the similarity at amino acid level was 95-100%. Nonsynonymous substitutions exceeding synonymous substitutions indicate the evolution of this protein through positive selection among domestic animals. Goat and sheep appear to have diverged from a common ancestor in phylogenetic analysis. Predicted protein structures of goat HSP 70 protein obtained from deduced amino acid sequence indicated that the functional amino acids involved in chaperoning through ATPase hydrolytic cycle and in uncoating of clathrin coated vesicles are highly conserved.
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Affiliation(s)
- Nitin Gade
- Division of Physiology and Climatology, Indian Veterinary Research Institute, Izatnagar, Uttar Pradesh, 243 122, India
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37
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Multifaceted role of heat shock protein 70 in neurons. Mol Neurobiol 2010; 42:114-23. [PMID: 20354811 DOI: 10.1007/s12035-010-8116-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 03/15/2010] [Indexed: 12/22/2022]
Abstract
Heat shock protein 70 (Hsp70) plays important roles in neural protection from stress by assisting cellular protein folding. In this review we discuss the current understanding of inducible and constitutive Hsp70 in maintaining and protecting neuronal synaptic function under normal and stressed conditions.
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38
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Cheli VT, Daniels RW, Godoy R, Hoyle DJ, Kandachar V, Starcevic M, Martinez-Agosto JA, Poole S, DiAntonio A, Lloyd VK, Chang HC, Krantz DE, Dell'Angelica EC. Genetic modifiers of abnormal organelle biogenesis in a Drosophila model of BLOC-1 deficiency. Hum Mol Genet 2009; 19:861-78. [PMID: 20015953 DOI: 10.1093/hmg/ddp555] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Biogenesis of lysosome-related organelles complex 1 (BLOC-1) is a protein complex formed by the products of eight distinct genes. Loss-of-function mutations in two of these genes, DTNBP1 and BLOC1S3, cause Hermansky-Pudlak syndrome, a human disorder characterized by defective biogenesis of lysosome-related organelles. In addition, haplotype variants within the same two genes have been postulated to increase the risk of developing schizophrenia. However, the molecular function of BLOC-1 remains unknown. Here, we have generated a fly model of BLOC-1 deficiency. Mutant flies lacking the conserved Blos1 subunit displayed eye pigmentation defects due to abnormal pigment granules, which are lysosome-related organelles, as well as abnormal glutamatergic transmission and behavior. Epistatic analyses revealed that BLOC-1 function in pigment granule biogenesis requires the activities of BLOC-2 and a putative Rab guanine-nucleotide-exchange factor named Claret. The eye pigmentation phenotype was modified by misexpression of proteins involved in intracellular protein trafficking; in particular, the phenotype was partially ameliorated by Rab11 and strongly enhanced by the clathrin-disassembly factor, Auxilin. These observations validate Drosophila melanogaster as a powerful model for the study of BLOC-1 function and its interactions with modifier genes.
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Affiliation(s)
- Verónica T Cheli
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Förster JR, Lochnit G, Stöhr H. Proteomic analysis of the membrane palmitoylated protein-4 (MPP4)-associated protein complex in the retina. Exp Eye Res 2008; 88:39-48. [PMID: 18955048 DOI: 10.1016/j.exer.2008.09.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/17/2008] [Accepted: 09/19/2008] [Indexed: 12/26/2022]
Abstract
Membrane palmitoylated protein-4 (MPP4) is a retina-specific scaffolding protein of the membrane-associated guanylate kinase family that has been implicated in organizing presynaptic protein complexes in the photoreceptor ribbon synapse. To isolate the components of this complex we applied a proteomic approach based on immunoaffinity chromatography with a monoclonal anti-MPP4 antibody followed by two-dimensional electrophoresis and mass spectrometry. Among the identified molecules were previously reported proteins of the MPP4 scaffolding complex including adaptor proteins Veli3 and Psd95. Here we demonstrate a selective association between MPP4 and the Psd95-beta isoform that is mediated by interaction of their N-terminal L27 domains. In addition, we have identified recoverin and Hsc70 as novel associated proteins of the MPP4 multiprotein complex in the retina. This study demonstrates the utility of anti-MPP4 antibody precipitation for the elucidation of the MPP4-associated protein complex, which is essential in understanding its precise role in signal transmission at the photoreceptor synapse.
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Affiliation(s)
- Johanna R Förster
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
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Hirst J, Sahlender DA, Li S, Lubben NB, Borner GHH, Robinson MS. Auxilin depletion causes self-assembly of clathrin into membraneless cages in vivo. Traffic 2008; 9:1354-71. [PMID: 18489706 PMCID: PMC2628426 DOI: 10.1111/j.1600-0854.2008.00764.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Auxilin is a cofactor for Hsc70-mediated uncoating of clathrin-coated vesicles (CCVs). However, small interfering RNA (siRNA) knockdown of the ubiquitous auxilin 2 in HeLa cells only moderately impairs clathrin-dependent trafficking. In this study, we show that HeLa cells also express auxilin 1, previously thought to be neuron specific, and that both auxilins need to be depleted for inhibition of clathrin-mediated endocytosis and intracellular sorting. Depleting both auxilins cause an ∼50% reduction in the number of clathrin-coated pits at the plasma membrane but enhances the association of clathrin and adaptors with intracellular membranes. CCV fractions isolated from auxilin-depleted cells have an ∼1.5-fold increase in clathrin content and more than fivefold increase in the amount of AP-2 adaptor complex and other endocytic machinery, with no concomitant increase in cargo. In addition, the structures isolated from auxilin-depleted cells are on average smaller than CCVs from control cells and are largely devoid of membrane, indicating that they are not CCVs but membraneless clathrin cages. Similar structures are observed by electron microscopy in intact auxilin-depleted HeLa cells. Together, these findings indicate that the two auxilins have overlapping functions and that they not only facilitate the uncoating of CCVs but also prevent the formation of nonproductive clathrin cages in the cytosol.
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Affiliation(s)
- Jennifer Hirst
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust, Addenbrooke's Hospital, Cambridge, UK.
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41
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Kandachar V, Bai T, Chang HC. The clathrin-binding motif and the J-domain of Drosophila Auxilin are essential for facilitating Notch ligand endocytosis. BMC DEVELOPMENTAL BIOLOGY 2008; 8:50. [PMID: 18466624 PMCID: PMC2391152 DOI: 10.1186/1471-213x-8-50] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 05/08/2008] [Indexed: 11/24/2022]
Abstract
Background Ligand endocytosis plays a critical role in regulating the activity of the Notch pathway. The Drosophila homolog of auxilin (dAux), a J-domain-containing protein best known for its role in the disassembly of clathrin coats from clathrin-coated vesicles, has recently been implicated in Notch signaling, although its exact mechanism remains poorly understood. Results To understand the role of auxilin in Notch ligand endocytosis, we have analyzed several point mutations affecting specific domains of dAux. In agreement with previous work, analysis using these stronger dAux alleles shows that dAux is required for several Notch-dependent processes, and its function during Notch signaling is required in the signaling cells. In support of the genetic evidences, the level of Delta appears elevated in dAux deficient cells, suggesting that the endocytosis of Notch ligand is disrupted. Deletion analysis shows that the clathrin-binding motif and the J-domain, when over-expressed, are sufficient for rescuing dAux phenotypes, implying that the recruitment of Hsc70 to clathrin is a critical role for dAux. However, surface labeling experiment shows that, in dAux mutant cells, Delta accumulates at the cell surface. In dAux mutant cells, clathrin appears to form large aggregates, although Delta is not enriched in these aberrant clathrin-positive structures. Conclusion Our data suggest that dAux mutations inhibit Notch ligand internalization at an early step during clathrin-mediated endocytosis, before the disassembly of clathrin-coated vesicles. Further, the inhibition of ligand endocytosis in dAux mutant cells possibly occurs due to depletion of cytosolic pools of clathrin via the formation of clathrin aggregates. Together, our observations argue that ligand endocytosis is critical for Notch signaling and auxilin participates in Notch signaling by facilitating ligand internalization.
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Affiliation(s)
- Vasundhara Kandachar
- Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, Indiana 47907-2054, USA.
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Mani M, Lee SY, Lucast L, Cremona O, Di Paolo G, De Camilli P, Ryan TA. The dual phosphatase activity of synaptojanin1 is required for both efficient synaptic vesicle endocytosis and reavailability at nerve terminals. Neuron 2008; 56:1004-18. [PMID: 18093523 DOI: 10.1016/j.neuron.2007.10.032] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Revised: 09/17/2007] [Accepted: 10/18/2007] [Indexed: 01/19/2023]
Abstract
Phosphoinositides have been implicated in synaptic vesicle recycling largely based on studies of enzymes that regulate phosphoinositide synthesis and hydrolysis. One such enzyme is synaptojanin1, a multifunctional protein conserved from yeast to humans, which contains two phosphoinositol phosphatase domains and a proline-rich domain. Genetic ablation of synaptojanin1 leads to pleiotropic defects in presynaptic function, including accumulation of free clathrin-coated vesicles and delayed vesicle reavailability, implicating this enzyme in postendocytic uncoating of vesicles. To further elucidate the role of synaptojanin1 at nerve terminals, we performed quantitative synaptic vesicle recycling assays in synj1(-/-) neurons. Our studies show that synaptojanin1 is also required for normal vesicle endocytosis. Defects in both endocytosis and postendocytic vesicle reavailability can be fully restored upon reintroduction of synaptojanin1. However, expression of synaptojanin1 with mutations abolishing catalytic activity of each phosphatase domain reveals that the dual action of both domains is required for normal synaptic vesicle internalization and reavailability.
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Affiliation(s)
- Meera Mani
- Department of Biochemistry, Weill Medical College of Cornell University, 1300 York Avenue, New York, NY 10021, USA
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Jiang J, Maes EG, Taylor AB, Wang L, Hinck AP, Lafer EM, Sousa R. Structural basis of J cochaperone binding and regulation of Hsp70. Mol Cell 2008; 28:422-33. [PMID: 17996706 DOI: 10.1016/j.molcel.2007.08.022] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Revised: 07/16/2007] [Accepted: 08/27/2007] [Indexed: 12/01/2022]
Abstract
The many protein processing reactions of the ATP-hydrolyzing Hsp70s are regulated by J cochaperones, which contain J domains that stimulate Hsp70 ATPase activity and accessory domains that present protein substrates to Hsp70s. We report the structure of a J domain complexed with a J responsive portion of a mammalian Hsp70. The J domain activates ATPase activity by directing the linker that connects the Hsp70 nucleotide binding domain (NBD) and substrate binding domain (SBD) toward a hydrophobic patch on the NBD surface. Binding of the J domain to Hsp70 displaces the SBD from the NBD, which may allow the SBD flexibility to capture diverse substrates. Unlike prokaryotic Hsp70, the SBD and NBD of the mammalian chaperone interact in the ADP state. Thus, although both nucleotides and J cochaperones modulate Hsp70 NBD:linker and NBD:SBD interactions, the intrinsic persistence of those interactions differs in different Hsp70s and this may optimize their activities for different cellular roles.
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Affiliation(s)
- Jianwen Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
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Hickman JA, Hardwick JM, Kaczmarek LK, Jonas EA. Bcl-xL inhibitor ABT-737 reveals a dual role for Bcl-xL in synaptic transmission. J Neurophysiol 2007; 99:1515-22. [PMID: 18160428 DOI: 10.1152/jn.00598.2007] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A role for BCL-xL in regulating neuronal activity is suggested by its dramatic effects on synaptic function and mitochondrial channel activity. When recombinant BCL-xL is injected into the giant presynaptic terminal of squid stellate ganglion or applied directly to mitochondrial outer membranes within the living terminal, it potentiates synaptic transmission acutely, and it produces mitochondrial channel activity. The squid, however, is a genetically intractable model, making it difficult to apply genetic tools in squid to explore the role of endogenous BCL-xL in synaptic function. Therefore the small molecule inhibitor ABT-737, a mimetic of the BH3-only protein BAD, binding to the BH3-binding domain pocket, was tested in squid, revealing a dual role for BCL-xL. ABT-737 slowed recovery of synaptic responses after repetitive synaptic activity, indicating that endogenous BCL-xL is necessary for timely recovery of rapidly firing synapses. Unexpectedly, however, ABT-737 also protected neurons from hypoxia-induced synaptic rundown and from increased permeability of the mitochondrial outer membrane during hypoxia. This implies that endogenous BCL-xL or a modified form of BCL-xL, such as the N-truncated, proteolytic, pro-apoptotic cleavage product, DeltaN BCL-xL, contributes to injurious responses of the hypoxic synapse. To determine if ABT-737 is also an inhibitor of DeltaN BCL-xL, recombinant DeltaN BCL-xL protein was injected into the synapse. ABT-737 potently inhibited synaptic rundown induced by recombinant DeltaN BCL-xL. These observations support the possibility that endogenous proteolysis or a functionally equivalent modification of BCL-xL is responsible for the deleterious effects of hypoxia on synaptic activity.
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Affiliation(s)
- John A Hickman
- Institut de Recherches Servier, Croissy sur Seine, France
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Romero-Pozuelo J, Dason JS, Atwood HL, Ferrús A. Chronic and acute alterations in the functional levels of Frequenins 1 and 2 reveal their roles in synaptic transmission and axon terminal morphology. Eur J Neurosci 2007; 26:2428-43. [DOI: 10.1111/j.1460-9568.2007.05877.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lu HAJ, Sun TX, Matsuzaki T, Yi XH, Eswara J, Bouley R, McKee M, Brown D. Heat shock protein 70 interacts with aquaporin-2 and regulates its trafficking. J Biol Chem 2007; 282:28721-28732. [PMID: 17636261 DOI: 10.1074/jbc.m611101200] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The trafficking of aquaporin-2 (AQP2) involves multiple complex pathways, including regulated, cAMP-, and cGMP-mediated pathways, as well as a constitutive recycling pathway. Although several accessory proteins have been indirectly implicated in AQP2 recycling, the direct protein-protein interactions that regulate this process remain largely unknown. Using yeast two-hybrid screening of a human kidney cDNA library, we have identified the 70-kDa heat shock proteins as AQP2-interacting proteins. Interaction was confirmed by mass spectrometry of proteins pulled down from rat kidney papilla extract using a GST-AQP2 C-terminal fusion protein (GST-A2C) as a bait, by co-immunoprecipitation (IP) assays, and by direct binding assays using purified hsc70 and the GST-A2C. The direct interaction of AQP2 with hsc70 is partially inhibited by ATP, and the Ser-256 residue in the AQP2 C terminus is important for this direct interaction. Vasopressin stimulation in cells enhances the interaction of hsc70 with AQP2 in IP assays, and vasopressin stimulation in vivo induces an increased co-localization of hsc70 and AQP2 on the apical membrane of principal cells in rat kidney collecting ducts. Functional knockdown of hsc70 activity in AQP2 expressing cells results in membrane accumulation of AQP2 and reduced endocytosis of rhodamine-transferrin. Our data also show that AQP2 interacts with hsp70 in multiple in vitro binding assays. Finally, in addition to hsc70 and hsp70, AQP2 interacts with several other key components of the endocytotic machinery in co-IP assays, including clathrin, dynamin, and AP2. To summarize, we have identified the 70-kDa heat shock proteins as a AQP2 interactors and have shown for hsc70 that this interaction is involved in AQP2 trafficking.
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Affiliation(s)
- Hua A J Lu
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114.
| | - Tian-Xiao Sun
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Toshiyuki Matsuzaki
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Xian-Hua Yi
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Jairam Eswara
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Richard Bouley
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Mary McKee
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114
| | - Dennis Brown
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114.
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Abstract
The ATP-dependent dissociation of clathrin from clathrin-coated vesicles (CCVs) by the molecular chaperone Hsc70 requires J-domain cofactor proteins, either auxilin or cyclin-G-associated kinase (GAK). Both the nerve-specific auxilin and the ubiquitous GAK induce CCVs to bind to Hsc70. The removal of auxilin or GAK from various organisms and cells has provided definitive evidence that Hsc70 uncoats CCVs in vivo. In addition, evidence from various studies has suggested that Hsc70 and auxilin are involved in several other key processes that occur during clathrin-mediated endocytosis. First, Hsc70 and auxilin are required for the clathrin exchange that occurs during coated-pit invagination and constriction; this clathrin exchange may catalyze any rearrangement of the clathrin-coated pit (CCP) structure that is required during invagination and constriction. Second, Hsc70 and auxilin may chaperone clathrin after it dissociates from CCPs so that it does not aggregate in the cytosol. Third, auxilin and Hsc70 may be involved in the rebinding of clathrin to the plasma membrane to form new CCPs and independently appear to chaperone adaptor proteins so that they can also rebind to membranes to nucleate the formation of new CCPs. Finally, if formation of the curved clathrin coat induces membrane curvature, then Hsc70 and auxilin provide the energy for this curvature by inducing ATP-dependent clathrin exchange and rearrangement during endocytosis and ATP-dependent dissociation of clathrin at the end of the cycle so that it is energetically primed to rebind to the plasma membrane.
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Affiliation(s)
- Evan Eisenberg
- Laboratory of Cell Biology, National Heart Lung Blood Institute, National Institutes of Health, Bethesda, MD 20892-0301, USA
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Bai L, Swayne LA, Braun JEA. The CSPα/G protein complex in PC12 cells. Biochem Biophys Res Commun 2007; 352:123-9. [PMID: 17113038 DOI: 10.1016/j.bbrc.2006.10.178] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Accepted: 10/27/2006] [Indexed: 11/28/2022]
Abstract
Cysteine string proteinalpha (CSPalpha) is a regulated vesicle protein and molecular chaperone that has been found to be critical for continuous synaptic transmission and is implicated in the defense against neurodegeneration. Previous work has revealed links between CSPalpha and heterotrimeric GTP binding protein (G protein) signal transduction pathways. We have shown that CSPalpha is a guanine nucleotide exchange factor (GEF) for Galphas. In vitro Hsc70 (70 kDa heat shock cognate protein) and SGT (small glutamine-rich tetratricopeptide repeat domain protein) switch CSPalpha from an inactive GEF to an active GEF. Here we have examined the cellular distribution of the CSPalpha system in the PC12 neuroendocrine cell line. CSPalpha, an established secretory vesicle protein, was found to concentrate in the processes of NGF-differentiated PC12 cells as expected. Gbeta subunits co-localized and Galphas subunits partially co-localized with CSPalpha. However, under the conditions examined, the GEF activity of CSPalpha is expected to be inactive, in that Hsc70 was not found in PC12 processes. These results indicate that CSPalpha activity is subject to regulation by factors that alter Hsc70 distribution and translocation within the cell.
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Affiliation(s)
- Liping Bai
- Hotchkiss Brain Institute, Department of Physiology and Biophysics, University of Calgary, Calgary, Alta., Canada T2N 4N1
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Buccellato MA, Carsillo T, Traylor Z, Oglesbee M. Heat shock protein expression in brain: a protective role spanning intrinsic thermal resistance and defense against neurotropic viruses. PROGRESS IN BRAIN RESEARCH 2007; 162:395-415. [PMID: 17645929 DOI: 10.1016/s0079-6123(06)62019-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Heat shock proteins (HSPs) play an important role in the maintenance of cellular homeostasis, particularly in response to stressful conditions that adversely affect normal cellular structure and function, such as hyperthermia. A remarkable intrinsic resistance of brain to hyperthermia reflects protection mediated by constitutive and induced expression of HSPs in both neurons and glia. Induced expression underlies the phenomenon of hyperthermic pre-reconditioning, where transient, low-intensity heating induces HSPs that protect brain from subsequent insult, reflecting the prolonged half-life of HSPs. The expression and activity of HSPs that is characteristic of nervous tissue plays a role not just in the maintenance and defense of cellular viability, but also in the preservation of neuron-specific luxury functions, particularly those that support synaptic activity. In response to hyperthermia, HSPs mediate preservation or rapid recovery of synaptic function up to the point where damage in other organ systems becomes evident and life threatening. Given the ability of HSPs to enhance gene expression by neurotropic viruses, the constitutive and inducible HSP expression profiles would seem to place nervous tissues at risk. However, we present evidence that the virus-HSP relationship can promote viral clearance in animals capable of mounting effective virus-specific cell-mediated immune responses, potentially reflecting HSP-dependent increases in viral antigenic burden, immune adjuvant effects and cross-presentation of viral antigen. Thus, the protective functions of HSPs span the well-characterized intracellular roles as chaperones to those that may directly or indirectly promote immune function.
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Affiliation(s)
- Matthew A Buccellato
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Rd., Columbus, OH 43210, USA
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Leshchyns'ka I, Sytnyk V, Richter M, Andreyeva A, Puchkov D, Schachner M. The Adhesion Molecule CHL1 Regulates Uncoating of Clathrin-Coated Synaptic Vesicles. Neuron 2006; 52:1011-25. [PMID: 17178404 DOI: 10.1016/j.neuron.2006.10.020] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 08/17/2006] [Accepted: 10/20/2006] [Indexed: 12/28/2022]
Abstract
In searching for binding partners of the intracellular domain of the immunoglobulin superfamily adhesion molecule CHL1, we identified the clathrin-uncoating ATPase Hsc70. CHL1 gene ablation resulted in reduced targeting of Hsc70 to the synaptic plasma membrane and synaptic vesicles, suggesting CHL1 as a synapse-targeting cue for Hsc70. CHL1 accumulates in presynaptic membranes and, in response to synapse activation, is targeted to synaptic vesicles by endocytosis. CHL1 deficiency or disruption of the CHL1/Hsc70 complex results in accumulation of abnormally high levels of clathrin-coated synaptic vesicles with a reduced ability to release clathrin. Generation of new clathrin-coated synaptic vesicles in an activity-dependent manner is inhibited when the CHL1/Hsc70 complex is disrupted, resulting in impaired uptake and release of FM dyes in synaptic boutons. Abnormalities in clathrin-dependent synaptic vesicle recycling may thus underlie brain malfunctions in humans and mice that carry mutations in the CHL1 gene.
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Affiliation(s)
- Iryna Leshchyns'ka
- Zentrum für Molekulare Neurobiologie, Universität Hamburg, Martinistrasse 52, 20246 Hamburg, Germany
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