151
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Epithelial sodium channel biogenesis and quality control in the early secretory pathway. Curr Opin Nephrol Hypertens 2018; 27:364-372. [DOI: 10.1097/mnh.0000000000000438] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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152
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Mukherjee M, Sabir S, O'Regan L, Sampson J, Richards MW, Huguenin-Dezot N, Ault JR, Chin JW, Zhuravleva A, Fry AM, Bayliss R. Mitotic phosphorylation regulates Hsp72 spindle localization by uncoupling ATP binding from substrate release. Sci Signal 2018; 11:11/543/eaao2464. [PMID: 30108182 DOI: 10.1126/scisignal.aao2464] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Hsp72 is a member of the 70-kDa heat shock family of molecular chaperones (Hsp70s) that comprise a nucleotide-binding domain (NBD) and a substrate-binding domain (SBD) connected by a linker that couples the exchange of adenosine diphosphate (ADP) for adenosine triphosphate (ATP) with the release of the protein substrate. Mitotic phosphorylation of Hsp72 by the kinase NEK6 at Thr66 located in the NBD promotes the localization of Hsp72 to the mitotic spindle and is required for efficient spindle assembly and chromosome congression and segregation. We determined the crystal structure of the Hsp72 NBD containing a genetically encoded phosphoserine at position 66. This revealed structural changes that stabilized interactions between subdomains within the NBD. ATP binding to the NBD of unmodified Hsp72 resulted in the release of substrate from the SBD, but phosphorylated Hsp72 retained substrate in the presence of ATP. Mutations that prevented phosphorylation-dependent subdomain interactions restored the connection between ATP binding and substrate release. Thus, phosphorylation of Thr66 is a reversible mechanism that decouples the allosteric connection between nucleotide binding and substrate release, providing further insight into the regulation of the Hsp70 family. We propose that phosphorylation of Hsp72 on Thr66 by NEK6 during mitosis promotes its localization to the spindle by stabilizing its interactions with components of the mitotic spindle.
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Affiliation(s)
- Manjeet Mukherjee
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Sarah Sabir
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Laura O'Regan
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Josephina Sampson
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Mark W Richards
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Nicolas Huguenin-Dezot
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - James R Ault
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Jason W Chin
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Anastasia Zhuravleva
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Andrew M Fry
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Richard Bayliss
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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153
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Hwang J, Qi L. Quality Control in the Endoplasmic Reticulum: Crosstalk between ERAD and UPR pathways. Trends Biochem Sci 2018; 43:593-605. [PMID: 30056836 PMCID: PMC6327314 DOI: 10.1016/j.tibs.2018.06.005] [Citation(s) in RCA: 327] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/30/2018] [Accepted: 06/11/2018] [Indexed: 01/14/2023]
Abstract
Endoplasmic reticulum (ER)-associated degradation (ERAD) and the unfolded protein response (UPR) are two key quality-control machineries in the cell. ERAD is responsible for the clearance of misfolded proteins in the ER for cytosolic proteasomal degradation, while UPR is activated in response to the accumulation of misfolded proteins. It has long been thought that ERAD is an integral part of UPR because expression of many ERAD genes is controlled by UPR; however, recent studies have suggested that ERAD has a direct role in controlling the protein turnover and abundance of IRE1α, the most conserved UPR sensor. Here, we review recent advances in our understanding of IRE1α activation and propose that UPR and ERAD engage in an intimate crosstalk to define folding capacity and maintain homeostasis in the ER.
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Affiliation(s)
- Jiwon Hwang
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA.
| | - Ling Qi
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48105, USA; Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48105, USA.
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154
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Shao H, Li X, Moses MA, Gilbert LA, Kalyanaraman C, Young ZT, Chernova M, Journey SN, Weissman JS, Hann B, Jacobson MP, Neckers L, Gestwicki JE. Exploration of Benzothiazole Rhodacyanines as Allosteric Inhibitors of Protein-Protein Interactions with Heat Shock Protein 70 (Hsp70). J Med Chem 2018; 61:6163-6177. [PMID: 29953808 DOI: 10.1021/acs.jmedchem.8b00583] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Cancer cells rely on the chaperone heat shock protein 70 (Hsp70) for survival and proliferation. Recently, benzothiazole rhodacyanines have been shown to bind an allosteric site on Hsp70, interrupting its binding to nucleotide-exchange factors (NEFs) and promoting cell death in breast cancer cell lines. However, proof-of-concept molecules, such as JG-98, have relatively modest potency (EC50 ≈ 0.7-0.4 μM) and are rapidly metabolized in animals. Here, we explored this chemical series through structure- and property-based design of ∼300 analogs, showing that the most potent had >10-fold improved EC50 values (∼0.05 to 0.03 μM) against two breast cancer cells. Biomarkers and whole genome CRISPRi screens confirmed members of the Hsp70 family as cellular targets. On the basis of these results, JG-231 was found to reduce tumor burden in an MDA-MB-231 xenograft model (4 mg/kg, ip). Together, these studies support the hypothesis that Hsp70 may be a promising target for anticancer therapeutics.
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Affiliation(s)
- Hao Shao
- Department of Pharmaceutical Chemistry , University of California at San Francisco , Sandler Center, 675 Nelson Rising Lane , San Francisco , California 94158 , United States
| | - Xiaokai Li
- Department of Pharmaceutical Chemistry , University of California at San Francisco , Sandler Center, 675 Nelson Rising Lane , San Francisco , California 94158 , United States
| | - Michael A Moses
- Urologic Oncology Branch, Center for Cancer Research , National Cancer Institute , Bethesda , Maryland 20892 , United States
| | - Luke A Gilbert
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute , University of California at San Francisco , San Francisco , California 94158 , United States
| | - Chakrapani Kalyanaraman
- Department of Pharmaceutical Chemistry , University of California at San Francisco , Sandler Center, 675 Nelson Rising Lane , San Francisco , California 94158 , United States
| | - Zapporah T Young
- Department of Pharmaceutical Chemistry , University of California at San Francisco , Sandler Center, 675 Nelson Rising Lane , San Francisco , California 94158 , United States
| | - Margarita Chernova
- Department of Pharmaceutical Chemistry , University of California at San Francisco , Sandler Center, 675 Nelson Rising Lane , San Francisco , California 94158 , United States
| | - Sara N Journey
- Department of Pharmaceutical Chemistry , University of California at San Francisco , Sandler Center, 675 Nelson Rising Lane , San Francisco , California 94158 , United States
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, Howard Hughes Medical Institute , University of California at San Francisco , San Francisco , California 94158 , United States
| | - Byron Hann
- Helen Diller Family Comprehensive Cancer Centre and Preclinical Therapeutics Core , University of California at San Francisco , San Francisco , California 94158 , United States
| | - Matthew P Jacobson
- Department of Pharmaceutical Chemistry , University of California at San Francisco , Sandler Center, 675 Nelson Rising Lane , San Francisco , California 94158 , United States
| | - Len Neckers
- Urologic Oncology Branch, Center for Cancer Research , National Cancer Institute , Bethesda , Maryland 20892 , United States
| | - Jason E Gestwicki
- Department of Pharmaceutical Chemistry , University of California at San Francisco , Sandler Center, 675 Nelson Rising Lane , San Francisco , California 94158 , United States
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155
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Chen Y, Murillo-Solano C, Kirkpatrick MG, Antoshchenko T, Park HW, Pizarro JC. Repurposing drugs to target the malaria parasite unfolding protein response. Sci Rep 2018; 8:10333. [PMID: 29985421 PMCID: PMC6037779 DOI: 10.1038/s41598-018-28608-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 06/26/2018] [Indexed: 01/19/2023] Open
Abstract
Drug resistant Plasmodium falciparum parasites represent a major obstacle in our efforts to control malaria, a deadly vector borne infectious disease. This situation creates an urgent need to find and validate new drug targets to contain the spread of the disease. Several genes associated with the unfolded protein response (UPR) including Glucose-regulated Protein 78 kDa (GRP78, also known as BiP) have been deemed potential drug targets. We explored the drug target potential of GRP78, a molecular chaperone that is a regulator of the UPR, for the treatment of P. falciparum parasite infection. By screening repurposed chaperone inhibitors that are anticancer agents, we showed that GRP78 inhibition is lethal to drug-sensitive and -resistant P. falciparum parasite strains in vitro. We correlated the antiplasmodial activity of the inhibitors with their ability to bind the malaria chaperone, by characterizing their binding to recombinant parasite GRP78. Furthermore, we determined the crystal structure of the ATP binding domain of P. falciparum GRP78 with ADP and identified structural features unique to the parasite. These data suggest that P. falciparum GRP78 can be a valid drug target and that its structural differences to human GRP78 emphasize potential to generate parasite specific compounds.
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Affiliation(s)
- Yun Chen
- Department of Molecular Biology and Biochemistry, School of Medicine, Tulane University, New Orleans, USA
| | - Claribel Murillo-Solano
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA
| | - Melanie G Kirkpatrick
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA
| | - Tetyana Antoshchenko
- Department of Molecular Biology and Biochemistry, School of Medicine, Tulane University, New Orleans, USA
| | - Hee-Won Park
- Department of Molecular Biology and Biochemistry, School of Medicine, Tulane University, New Orleans, USA.,Vector Borne Infectious Disease Research Center (VBIDRC), Tulane University, New Orleans, USA
| | - Juan C Pizarro
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA. .,Vector Borne Infectious Disease Research Center (VBIDRC), Tulane University, New Orleans, USA.
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156
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Zhang Y, Zhou Z, Wang L, Huang B. Transcriptome, expression, and activity analyses reveal a vital heat shock protein 70 in the stress response of stony coral Pocillopora damicornis. Cell Stress Chaperones 2018; 23:711-721. [PMID: 29435724 PMCID: PMC6045544 DOI: 10.1007/s12192-018-0883-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Revised: 01/25/2018] [Accepted: 01/30/2018] [Indexed: 12/29/2022] Open
Abstract
Coral bleaching occurs worldwide with increasing frequencies and intensities, which is caused by the stress response of stony coral to environmental change, especially increased sea surface temperature. In the present study, transcriptome, expression, and activity analyses were employed to illustrate the underlying molecular mechanisms of heat shock protein 70 (HSP70) in the stress response of coral to environmental changes. The domain analyses of assembled transcripts revealed 30 HSP70 gene contigs in stony coral Pocillopora damicornis. One crucial HSP70 (PdHSP70) was observed, whose expressions were induced by both elevated temperature and ammonium after expression difference analysis. The complete complementary DNA (cDNA) sequence of PdHSP70 was identified, which encoded a polypeptide of 650 amino acids with a molecular weight of 71.93 kDa. The deduced amino acid sequence of PdHSP70 contained a HSP70 domain (from Pro8 to Gly616), and it shared the highest similarity (95%) with HSP70 from Stylophora pistillata. The expression level of PdHSP70 gene increased significantly at 12 h, and returned to the initial level at 24 h after the stress of high temperature (32 °C). The cDNA fragment encoding the mature peptide of PdHSP70 was recombined and expressed in the prokaryotic expression system. The ATPase activity of recombinant PdHSP70 protein was determined, and it did not change significantly in a wide range of temperature from 25 to 40 °C. These results collectively suggested that PdHSP70 was a vital heat shock protein 70 in the stony coral P. damicornis, whose mRNA expression could be induced by diverse environmental stress and whose activity could remain stable under heat stress. PdHSP70 might be involved in the regulation of the bleaching owing to heat stress in the stony coral P. damicornis.
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Affiliation(s)
- Yidan Zhang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan, 570228, China
| | - Zhi Zhou
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan, 570228, China.
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan, 570228, China.
- Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, Hainan, 570228, China.
| | - Lingui Wang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan, 570228, China
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan, 570228, China
- Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, Hainan, 570228, China
| | - Bo Huang
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, Hainan, 570228, China
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan, 570228, China
- Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, Hainan, 570228, China
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157
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Jores T, Lawatscheck J, Beke V, Franz-Wachtel M, Yunoki K, Fitzgerald JC, Macek B, Endo T, Kalbacher H, Buchner J, Rapaport D. Cytosolic Hsp70 and Hsp40 chaperones enable the biogenesis of mitochondrial β-barrel proteins. J Cell Biol 2018; 217:3091-3108. [PMID: 29930205 PMCID: PMC6122992 DOI: 10.1083/jcb.201712029] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 05/04/2018] [Accepted: 05/31/2018] [Indexed: 11/22/2022] Open
Abstract
Mitochondrial β-barrel proteins are imported from the cytosol into the organelle. Jores et al. provide new insights into the early events of this process by describing an array of cytosolic chaperones and cochaperones that associate with newly synthesized β-barrel proteins and assure their optimal biogenesis. Mitochondrial β-barrel proteins are encoded in the nucleus, translated by cytosolic ribosomes, and then imported into the organelle. Recently, a detailed understanding of the intramitochondrial import pathway of β-barrel proteins was obtained. In contrast, it is still completely unclear how newly synthesized β-barrel proteins reach the mitochondrial surface in an import-competent conformation. In this study, we show that cytosolic Hsp70 chaperones and their Hsp40 cochaperones Ydj1 and Sis1 interact with newly synthesized β-barrel proteins. These interactions are highly relevant for proper biogenesis, as inhibiting the activity of the cytosolic Hsp70, preventing its docking to the mitochondrial receptor Tom70, or depleting both Ydj1 and Sis1 resulted in a significant reduction in the import of such substrates into mitochondria. Further experiments demonstrate that the interactions between β-barrel proteins and Hsp70 chaperones and their importance are conserved also in mammalian cells. Collectively, this study outlines a novel mechanism in the early events of the biogenesis of mitochondrial outer membrane β-barrel proteins.
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Affiliation(s)
- Tobias Jores
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Jannis Lawatscheck
- Center for Integrated Protein Science, Department Chemie, Technische Universität München, Garching, Germany
| | - Viktor Beke
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Mirita Franz-Wachtel
- Proteome Center Tübingen, Interfaculty Institute for Cell Biology, University of Tübingen, Tübingen, Germany
| | - Kaori Yunoki
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Julia C Fitzgerald
- Department of Neurodegenerative Diseases and Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Boris Macek
- Proteome Center Tübingen, Interfaculty Institute for Cell Biology, University of Tübingen, Tübingen, Germany
| | - Toshiya Endo
- Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
| | - Hubert Kalbacher
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Johannes Buchner
- Center for Integrated Protein Science, Department Chemie, Technische Universität München, Garching, Germany
| | - Doron Rapaport
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
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158
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Cunningham TJ, Greenstein J, Yao L, Fischer I, Connors T. Heptamer Peptide Disassembles Native Amyloid in Human Plasma Through Heat Shock Protein 70. Rejuvenation Res 2018; 21:527-534. [PMID: 29651925 DOI: 10.1089/rej.2017.2049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Proteostasis, which includes the repair and disposal of misfolded proteins, depends, in part, on the activity of heat shock proteins (HSPs), a well-known class of chaperone molecules. When this process fails, abnormally folded proteins may accumulate in cells, tissues, and blood. These species are a hallmark of protein aggregation diseases, but also amass during aging, often in the absence of an identified clinical disorder. We report that a neuroprotective cyclic heptapeptide, CHEC-7, which has been applied systemically as a therapeutic in animal neurodegeneration models, disrupts such aggregates and inhibits amyloidogenesis when added in nanomolar concentrations to human plasma. This effect includes aggregates of amyloid beta (Aβ1-40, 1-42), prominent features of Alzheimer's disease pathology. The activity of endogenous HSP70, a recently discovered target of the peptide, is required as demonstrated by both antibody blocking and application of pifithrin-μ, an HSP70 inhibitor. CHEC-7 is the first high-affinity compound to stimulate HSP70's disaggregase activity and therefore enable this endogenous mechanism in a human systemic environment, increasing the likelihood of a convenient therapy for protein aggregate disease, including age-related failures of protein repair.
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Affiliation(s)
- Timothy J Cunningham
- 1 Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | | | - Lihua Yao
- 1 Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Itzhak Fischer
- 1 Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
| | - Theresa Connors
- 1 Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania
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159
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Johnston CL, Marzano NR, van Oijen AM, Ecroyd H. Using Single-Molecule Approaches to Understand the Molecular Mechanisms of Heat-Shock Protein Chaperone Function. J Mol Biol 2018; 430:4525-4546. [PMID: 29787765 DOI: 10.1016/j.jmb.2018.05.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 05/11/2018] [Accepted: 05/13/2018] [Indexed: 02/01/2023]
Abstract
The heat-shock proteins (Hsp) are a family of molecular chaperones, which collectively form a network that is critical for the maintenance of protein homeostasis. Traditional ensemble-based measurements have provided a wealth of knowledge on the function of individual Hsps and the Hsp network; however, such techniques are limited in their ability to resolve the heterogeneous, dynamic and transient interactions that molecular chaperones make with their client proteins. Single-molecule techniques have emerged as a powerful tool to study dynamic biological systems, as they enable rare and transient populations to be identified that would usually be masked in ensemble measurements. Thus, single-molecule techniques are particularly amenable for the study of Hsps and have begun to be used to reveal novel mechanistic details of their function. In this review, we discuss the current understanding of the chaperone action of Hsps and how gaps in the field can be addressed using single-molecule methods. Specifically, this review focuses on the ATP-independent small Hsps and the broader Hsp network and describes how these dynamic systems are amenable to single-molecule techniques.
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Affiliation(s)
- Caitlin L Johnston
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
| | - Nicholas R Marzano
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
| | - Antoine M van Oijen
- School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
| | - Heath Ecroyd
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales 2522, Australia; Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
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160
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Nitika, Truman AW. Endogenous epitope tagging of heat shock protein 70 isoform Hsc70 using CRISPR/Cas9. Cell Stress Chaperones 2018; 23:347-355. [PMID: 28944418 PMCID: PMC5904078 DOI: 10.1007/s12192-017-0845-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/13/2017] [Accepted: 09/16/2017] [Indexed: 12/31/2022] Open
Abstract
Heat shock protein 70 (Hsp70) is an evolutionarily well-conserved molecular chaperone involved in several cellular processes such as folding of proteins, modulating protein-protein interactions, and transport of proteins across the membrane. Binding partners of Hsp70 (known as "clients") are identified on an individual basis as researchers discover their particular protein of interest binds to Hsp70. A full complement of Hsp70 interactors under multiple stress conditions remains to be determined. A promising approach to characterizing the Hsp70 "interactome" is the use of protein epitope tagging and then affinity purification followed by mass spectrometry (AP-MS/MS). AP-MS analysis is a widely used method to decipher protein-protein interaction networks and identifying protein functions. Conventionally, the proteins are overexpressed ectopically which interferes with protein complex stoichiometry, skewing AP-MS/MS data. In an attempt to solve this issue, we used CRISPR/Cas9-mediated gene editing to integrate a tandem-affinity (TAP) epitope tag into the genomic locus of HSC70. This system offers several benefits over existing expression systems including native expression, no requirement for selection, and homogeneity between cells. This cell line, freely available to chaperone researchers, will aid in small and large-scale protein interaction studies as well as the study of biochemical activities and structure-function relationships of the Hsc70 protein.
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Affiliation(s)
- Nitika
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Andrew W Truman
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, 28223, USA.
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161
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Piscopo M, Notariale R, Rabbito D, Ausió J, Olanrewaju OS, Guerriero G. Mytilus galloprovincialis (Lamarck, 1819) spermatozoa: hsp70 expression and protamine-like protein property studies. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:12957-12966. [PMID: 29478169 DOI: 10.1007/s11356-018-1570-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 02/14/2018] [Indexed: 04/16/2023]
Abstract
In this work, we describe results of the reproductive health monitoring studies in Mytilus galloprovincialis following spermatozoa hsp70 expression and protamine-like protein properties. Mussels control (ctr) were released within cages for 30 days in three different marine sites near Naples (Campania, Italy): Bagnoli south (BAs) and Bagnoli north (BAn), both close to a disposal metallurgical factory and in Capo Miseno (CM). Studies of hsp70 gene expression carried out, by RT-qPCR, in mussel spermatozoa have shown varied expression levels, particularly 5, 13, and 15-fold more than ctr in CM, BAs, and BAn, respectively, indicating highest involvement of stress proteins in spermatozoa of mussels in Bagnoli. In order to evaluate the possible risk on Mytilus galloprovincialis sustainability loss, electrophoretic analyses were performed on protamine-like proteins (PL) of collected spermatozoa. The results showed that CM PL were apparently unaltered with respect to ctr PL, while BAs and BAn PL appeared in part in the form of peptides and in part as bands with low mobility. Further, CM and BAs PL showed, by electrophoretic mobility shift assay, a decrease in DNA binding ability and a change in their DNA binding mode. The results of this investigation show the usefulness of the study of alterations of spermatozoa hsp70 expression and protamine-like protein properties for eco-toxicological evaluation using Mytilus galloprovincialis as a bioindicator.
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Affiliation(s)
- Marina Piscopo
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, 80126, Naples, Italy.
| | - Rosaria Notariale
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, 80126, Naples, Italy
| | - Dea Rabbito
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, 80126, Naples, Italy
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | | | - Giulia Guerriero
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, 80126, Naples, Italy
- Interdepartmental Research Center for Environment (I.R.C.Env.), Università degli Studi di Napoli, Federico II, Naples, Italy
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162
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Morán Luengo T, Kityk R, Mayer MP, Rüdiger SGD. Hsp90 Breaks the Deadlock of the Hsp70 Chaperone System. Mol Cell 2018; 70:545-552.e9. [PMID: 29706537 DOI: 10.1016/j.molcel.2018.03.028] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/17/2018] [Accepted: 03/23/2018] [Indexed: 10/17/2022]
Abstract
Protein folding in the cell requires ATP-driven chaperone machines such as the conserved Hsp70 and Hsp90. It is enigmatic how these machines fold proteins. Here, we show that Hsp90 takes a key role in protein folding by breaking an Hsp70-inflicted folding block, empowering protein clients to fold on their own. At physiological concentrations, Hsp70 stalls productive folding by binding hydrophobic, core-forming segments. Hsp90 breaks this deadlock and restarts folding. Remarkably, neither Hsp70 nor Hsp90 alters the folding rate despite ensuring high folding yields. In fact, ATP-dependent chaperoning is restricted to the early folding phase. Thus, the Hsp70-Hsp90 cascade does not fold proteins, but instead prepares them for spontaneous, productive folding. This stop-start mechanism is conserved from bacteria to man, assigning also a general function to bacterial Hsp90, HtpG. We speculate that the decreasing hydrophobicity along the Hsp70-Hsp90 cascade may be crucial for enabling spontaneous folding.
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Affiliation(s)
- Tania Morán Luengo
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands; Science for Life, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Roman Kityk
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Matthias P Mayer
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
| | - Stefan G D Rüdiger
- Cellular Protein Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands; Science for Life, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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163
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Gurusinghe KRDSNS, Mishra A, Mishra S. Glucose-regulated protein 78 substrate-binding domain alters its conformation upon EGCG inhibitor binding to nucleotide-binding domain: Molecular dynamics studies. Sci Rep 2018; 8:5487. [PMID: 29615633 PMCID: PMC5882873 DOI: 10.1038/s41598-018-22905-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 03/01/2018] [Indexed: 12/13/2022] Open
Abstract
Glucose-regulated protein 78 (GRP78), is overexpressed in glioblastoma, other tumors and during viral and bacterial infections, and so, it is postulated to be a key drug target. EGCG, an ATP-competitive natural inhibitor, inhibits GRP78 effect in glioblastoma. Structural basis of its action on GRP78 nucleotide-binding domain and selectivity has been investigated. We were interested in exploring the large-scale conformational movements travelling to substrate-binding domain via linker region. Conformational effects of EGCG inhibitor as well as ATP on full length GRP78 protein were studied using powerful MD simulations. Binding of EGCG decreases mobility of residues in SBDα lid region as compared to ATP-bound state and similar to apo state. The decreased mobility may prevent its opening and closing over SBDβ. This hindrance to SBDα subdomain movement, in turn, may reduce the binding of substrate peptide to SBDβ. EGCG binding folds the protein stably as opposed to ATP binding. Several results from EGCG binding simulations are similar to that of the apo state. Key insights from these results reveal that after EGCG binding upon competitive inhibition with ATP, GRP78 conformation may revert to that of inactive, apo state. Further, SBD may adopt a semi-open conformation unable to facilitate association of substrates.
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Affiliation(s)
| | - Aanchal Mishra
- Ronin Institute for Independent Scholarship, Montclair, NJ, USA.,Osmania University, Hyderabad, Telangana, India
| | - Seema Mishra
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India.
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164
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Substrate Binding Switches the Conformation at the Lynchpin Site in the Substrate-Binding Domain of Human Hsp70 to Enable Allosteric Interdomain Communication. Molecules 2018; 23:molecules23030528. [PMID: 29495458 PMCID: PMC6017645 DOI: 10.3390/molecules23030528] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 02/18/2018] [Accepted: 02/24/2018] [Indexed: 01/11/2023] Open
Abstract
The stress-induced 70 kDa heat shock protein (Hsp70) functions as a molecular chaperone to maintain protein homeostasis. Hsp70 contains an N-terminal ATPase domain (NBD) and a C-terminal substrate-binding domain (SBD). The SBD is divided into the β subdomain containing the substrate-binding site (βSBD) and the α-helical subdomain (αLid) that covers the βSBD. In this report, the solution structures of two different forms of the SBD from human Hsp70 were solved. One structure shows the αLid bound to the substrate-binding site intramolecularly, whereas this intramolecular binding mode is absent in the other structure solved. Structural comparison of the two SBDs from Hsp70 revealed that client-peptide binding rearranges residues at the interdomain contact site, which impairs interdomain contact between the SBD and the NBD. Peptide binding also disrupted the inter-subdomain interaction connecting the αLid to the βSBD, which allows the binding of the αLid to the NBD. The results provide a mechanism for interdomain communication upon substrate binding from the SBD to the NBD via the lynchpin site in the βSBD of human Hsp70. In comparison to the bacterial ortholog, DnaK, some remarkable differences in the allosteric signal propagation among residues within the Hsp70 SBD exist.
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165
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Jilly R, Khan NZ, Aronsson H, Schneider D. Dynamin-Like Proteins Are Potentially Involved in Membrane Dynamics within Chloroplasts and Cyanobacteria. FRONTIERS IN PLANT SCIENCE 2018; 9:206. [PMID: 29520287 PMCID: PMC5827413 DOI: 10.3389/fpls.2018.00206] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 02/02/2018] [Indexed: 05/24/2023]
Abstract
Dynamin-like proteins (DLPs) are a family of membrane-active proteins with low sequence identity. The proteins operate in different organelles in eukaryotic cells, where they trigger vesicle formation, membrane fusion, or organelle division. As discussed here, representatives of this protein family have also been identified in chloroplasts and DLPs are very common in cyanobacteria. Since cyanobacteria and chloroplasts, an organelle of bacterial origin, have similar internal membrane systems, we suggest that DLPs are involved in membrane dynamics in cyanobacteria and chloroplasts. Here, we discuss the features and activities of DLPs with a focus on their potential presence and activity in chloroplasts and cyanobacteria.
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Affiliation(s)
- Ruven Jilly
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Nadir Zaman Khan
- Department of Biotechnology, University of Malakand, Malakand, Pakistan
| | - Henrik Aronsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Dirk Schneider
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Mainz, Germany
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166
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Sekhar A, Velyvis A, Zoltsman G, Rosenzweig R, Bouvignies G, Kay LE. Conserved conformational selection mechanism of Hsp70 chaperone-substrate interactions. eLife 2018; 7:32764. [PMID: 29460778 PMCID: PMC5819949 DOI: 10.7554/elife.32764] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 12/27/2017] [Indexed: 12/17/2022] Open
Abstract
Molecular recognition is integral to biological function and frequently involves preferred binding of a molecule to one of several exchanging ligand conformations in solution. In such a process the bound structure can be selected from the ensemble of interconverting ligands a priori (conformational selection, CS) or may form once the ligand is bound (induced fit, IF). Here we focus on the ubiquitous and conserved Hsp70 chaperone which oversees the integrity of the cellular proteome through its ATP-dependent interaction with client proteins. We directly quantify the flux along CS and IF pathways using solution NMR spectroscopy that exploits a methyl TROSY effect and selective isotope-labeling methodologies. Our measurements establish that both bacterial and human Hsp70 chaperones interact with clients by selecting the unfolded state from a pre-existing array of interconverting structures, suggesting a conserved mode of client recognition among Hsp70s and highlighting the importance of molecular dynamics in this recognition event. Proteins are the workhorses of a cell and are involved in almost all biological processes. Newly made proteins need to ‘fold’ into precise three-dimensional shapes in order to carry out their roles. However, proteins sometimes fold incorrectly or unfold. These protein forms are not able to work effectively and in some cases may even cause diseases. Chaperone proteins help other proteins to fold correctly and are found in living organisms ranging in complexity from bacteria to humans. There are many different types of chaperones that play different roles inside cells. One, called Hsp70, binds to proteins that are incorrectly folded to help them to mature into their correct structures. However, it was not clear whether Hsp70 can also associate with the mature, correctly folded form of the proteins. A technique called Nuclear Magnetic Resonance (NMR) spectroscopy can distinguish between mature, unfolded and chaperone-bound forms of the same protein. Sekhar et al. therefore used NMR to investigate which forms of a protein Hsp70 binds to. This revealed that both the bacterial and human versions of the Hsp70 chaperone interact only with unfolded proteins. The results presented by Sekhar et al. also explain why Hsp70 does not disrupt the routine workings of the cell: because it does not bind to mature forms of proteins. These observations extend our understanding of how chaperones assist in folding proteins, and fit into a broader research theme exploring how proteins recognize one another. It will now be interesting to see whether the same mechanism holds for more complex forms of proteins, such as aggregates, or larger protein structures with regions of both folded and unfolded elements.
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Affiliation(s)
- Ashok Sekhar
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Algirdas Velyvis
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Guy Zoltsman
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Rina Rosenzweig
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada.,Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Guillaume Bouvignies
- Laboratoire des Biomolécules, Département de chimie, École normale supérieure, UPMC Univ. Paris 06, CNRS, PSL Research University, Paris, France.,Sorbonne Universités, UPMC Univ. Paris 06, École normale supérieure, CNRS, Laboratoire des Biomolécules, Paris, France
| | - Lewis E Kay
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Biochemistry, University of Toronto, Toronto, Canada.,Hospital for Sick Children, Program in Molecular Medicine, University Avenue, Toronto, Canada
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167
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O'Donnell JP, Marsh HM, Sondermann H, Sevier CS. Disrupted Hydrogen-Bond Network and Impaired ATPase Activity in an Hsc70 Cysteine Mutant. Biochemistry 2018; 57:1073-1086. [PMID: 29300467 DOI: 10.1021/acs.biochem.7b01005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The ATPase domain of members of the 70 kDa heat shock protein (Hsp70) family shows a high degree of sequence, structural, and functional homology across species. A broadly conserved residue within the Hsp70 ATPase domain that captured our attention is an unpaired cysteine, positioned proximal to the site of nucleotide binding. Prior studies of several Hsp70 family members show this cysteine is not required for Hsp70 ATPase activity, yet select amino acid replacements of the cysteine can dramatically alter ATP hydrolysis. Moreover, post-translational modification of the cysteine has been reported to limit ATP hydrolysis for several Hsp70s. To better understand the underlying mechanism for how perturbation of this noncatalytic residue modulates Hsp70 function, we determined the structure for a cysteine-to-tryptophan mutation in the constitutively expressed, mammalian Hsp70 family member Hsc70. Our work reveals that the steric hindrance produced by a cysteine-to-tryptophan mutation disrupts the hydrogen-bond network within the active site, resulting in a loss of proper catalytic magnesium coordination. We propose that a similarly altered active site is likely observed upon post-translational oxidation. We speculate that the subtle changes we detect in the hydrogen-bonding network may relate to the previously reported observation that cysteine oxidation can influence Hsp70 interdomain communication.
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Affiliation(s)
- John P O'Donnell
- Department of Molecular Medicine, Cornell University , Ithaca, New York 14853, United States
| | - Heather M Marsh
- Department of Molecular Medicine, Cornell University , Ithaca, New York 14853, United States
| | - Holger Sondermann
- Department of Molecular Medicine, Cornell University , Ithaca, New York 14853, United States
| | - Carolyn S Sevier
- Department of Molecular Medicine, Cornell University , Ithaca, New York 14853, United States
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168
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Farkas Z, Kalapis D, Bódi Z, Szamecz B, Daraba A, Almási K, Kovács K, Boross G, Pál F, Horváth P, Balassa T, Molnár C, Pettkó-Szandtner A, Klement É, Rutkai E, Szvetnik A, Papp B, Pál C. Hsp70-associated chaperones have a critical role in buffering protein production costs. eLife 2018; 7:29845. [PMID: 29377792 PMCID: PMC5788500 DOI: 10.7554/elife.29845] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 12/23/2017] [Indexed: 02/01/2023] Open
Abstract
Proteins are necessary for cellular growth. Concurrently, however, protein production has high energetic demands associated with transcription and translation. Here, we propose that activity of molecular chaperones shape protein burden, that is the fitness costs associated with expression of unneeded proteins. To test this hypothesis, we performed a genome-wide genetic interaction screen in baker's yeast. Impairment of transcription, translation, and protein folding rendered cells hypersensitive to protein burden. Specifically, deletion of specific regulators of the Hsp70-associated chaperone network increased protein burden. In agreement with expectation, temperature stress, increased mistranslation and a chemical misfolding agent all substantially enhanced protein burden. Finally, unneeded protein perturbed interactions between key components of the Hsp70-Hsp90 network involved in folding of native proteins. We conclude that specific chaperones contribute to protein burden. Our work indicates that by minimizing the damaging impact of gratuitous protein overproduction, chaperones enable tolerance to massive changes in genomic expression.
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Affiliation(s)
- Zoltán Farkas
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Dorottya Kalapis
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Zoltán Bódi
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Béla Szamecz
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Andreea Daraba
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Karola Almási
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Károly Kovács
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Gábor Boross
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Ferenc Pál
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Péter Horváth
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Tamás Balassa
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Csaba Molnár
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Aladár Pettkó-Szandtner
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary.,Laboratory of Proteomic Research, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Éva Klement
- Laboratory of Proteomic Research, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Edit Rutkai
- Division for Biotechnology, Bay Zoltán Nonprofit Ltd, Budapest, Hungary
| | - Attila Szvetnik
- Division for Biotechnology, Bay Zoltán Nonprofit Ltd, Budapest, Hungary
| | - Balázs Papp
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Csaba Pál
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
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169
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Higgins R, Kabbaj MH, Hatcher A, Wang Y. The absence of specific yeast heat-shock proteins leads to abnormal aggregation and compromised autophagic clearance of mutant Huntingtin proteins. PLoS One 2018; 13:e0191490. [PMID: 29346421 PMCID: PMC5773196 DOI: 10.1371/journal.pone.0191490] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 01/05/2018] [Indexed: 11/25/2022] Open
Abstract
The functionality of a protein depends on its correct folding, but newly synthesized proteins are susceptible to aberrant folding and aggregation. Heat shock proteins (HSPs) function as molecular chaperones that aid in protein folding and the degradation of misfolded proteins. Trinucleotide (CAG) repeat expansion in the Huntingtin gene (HTT) results in the expression of misfolded Huntingtin protein (Htt), which contributes to the development of Huntington’s disease. We previously found that the degradation of mutated Htt with polyQ expansion (Htt103QP) depends on both ubiquitin proteasome system and autophagy. However, the role of heat shock proteins in the clearance of mutated Htt remains poorly understood. Here, we report that cytosolic Hsp70 (Ssa family), its nucleotide exchange factors (Sse1 and Fes1), and a Hsp40 co-chaperone (Ydj1) are required for inclusion body formation of Htt103QP proteins and their clearance via autophagy. Extended induction of Htt103QP-GFP leads to the formation of a single inclusion body in wild-type yeast cells, but mutant cells lacking these HSPs exhibit increased number of Htt103QP aggregates. Most notably, we detected more aggregated forms of Htt103QP in sse1Δ mutant cells using an agarose gel assay. Increased protein aggregates are also observed in these HSP mutants even in the absence Htt103QP overexpression. Importantly, these HSPs are required for autophagy-mediated Htt103QP clearance, but are less critical for proteasome-dependent degradation. These findings suggest a chaperone network that facilitates inclusion body formation of misfolded proteins and the subsequent autophagic clearance.
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Affiliation(s)
- Ryan Higgins
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, United States of America
| | - Marie-Helene Kabbaj
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, United States of America
| | - Alexa Hatcher
- College of Nursing, Florida State University, Tallahassee, Florida, United States of America
| | - Yanchang Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, United States of America
- * E-mail:
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170
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Trapero‐Mozos A, Morris WL, Ducreux LJM, McLean K, Stephens J, Torrance L, Bryan GJ, Hancock RD, Taylor MA. Engineering heat tolerance in potato by temperature-dependent expression of a specific allele of HEAT-SHOCK COGNATE 70. PLANT BIOTECHNOLOGY JOURNAL 2018; 16:197-207. [PMID: 28509353 PMCID: PMC5785350 DOI: 10.1111/pbi.12760] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/03/2017] [Accepted: 05/11/2017] [Indexed: 05/23/2023]
Abstract
For many commercial potato cultivars, tuber yield is optimal at average daytime temperatures in the range of 14-22 °C. Further rises in ambient temperature can reduce or completely inhibit potato tuber production, with damaging consequences for both producer and consumer. The aim of this study was to use a genetic screen based on a model tuberization assay to identify quantitative trait loci (QTL) associated with enhanced tuber yield. A candidate gene encoding HSc70 was identified within one of the three QTL intervals associated with elevated yield in a Phureja-Tuberosum hybrid diploid potato population (06H1). A particular HSc70 allelic variant was linked to elevated yield in the 06H1 progeny. Expression of this allelic variant was much higher than other alleles, particularly on exposure to moderately elevated temperature. Transient expression of this allele in Nicotiana benthamiana resulted in significantly enhanced tolerance to elevated temperature. An TA repeat element was present in the promoter of this allele, but not in other HSc70 alleles identified in the population. Expression of the HSc70 allelic variant under its native promoter in the potato cultivar Desiree resulted in enhanced HSc70 expression at elevated temperature. This was reflected in greater tolerance to heat stress as determined by improved yield under moderately elevated temperature in a model nodal cutting tuberization system and in plants grown from stem cuttings. Our results identify HSc70 expression level as a significant factor influencing yield stability under moderately elevated temperature and identify specific allelic variants of HSc70 for the induction of thermotolerance via conventional introgression or molecular breeding approaches.
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Affiliation(s)
| | - Wayne L. Morris
- Cell and Molecular SciencesThe James Hutton InstituteDundeeUK
| | | | - Karen McLean
- Cell and Molecular SciencesThe James Hutton InstituteDundeeUK
| | | | - Lesley Torrance
- School of BiologyUniversity of St AndrewsSt AndrewsFifeUK
- Cell and Molecular SciencesThe James Hutton InstituteDundeeUK
| | - Glenn J. Bryan
- Cell and Molecular SciencesThe James Hutton InstituteDundeeUK
| | | | - Mark A. Taylor
- Cell and Molecular SciencesThe James Hutton InstituteDundeeUK
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171
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Blasius E, Gülden E, Kolb H, Habich C, Burkart V. The Autoantigenic Proinsulin B-Chain Peptide B11-23 Synergises with the 70 kDa Heat Shock Protein DnaK in Macrophage Stimulation. J Diabetes Res 2018; 2018:4834673. [PMID: 30622969 PMCID: PMC6304834 DOI: 10.1155/2018/4834673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 10/10/2018] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Heat shock proteins (Hsp) act as intracellular chaperones and in addition are used as adjuvant in vaccines of peptides complexed with recombinant Hsp. By interacting with autologous peptides, Hsp may promote the induction of autoimmune reactivity. OBJECTIVE Here, we analysed whether the effect of Hsp on macrophages is modulated by insulin peptides known to interact with Hsp. RESULTS Combinations of the 70 kDa Hsp DnaK with peptide B11-23 from the core region of the proinsulin B-chain induced the release of the inflammatory mediators interleukin-6, tumor necrosis factor α, and interleukin-1β from cells of human and murine macrophage lines. In parallel, there was high-affinity binding of B11-23 to DnaK. DnaK mixed with peptides from other regions of the insulin molecule did not stimulate cytokine secretion. DnaK alone induced little cytokine production, and peptides alone induced none. CONCLUSION The macrophage-stimulating potential of Hsp70 family proteins when combined with the proinsulin B-chain peptide B11-23 may contribute to the immunodominance of this peptide in the development of beta cell-directed autoimmunity in type 1 diabetes.
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Affiliation(s)
- Elias Blasius
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, D-40225 Düsseldorf, Germany
| | - Elke Gülden
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, D-40225 Düsseldorf, Germany
| | - Hubert Kolb
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, D-40225 Düsseldorf, Germany
- West German Center of Diabetes and Health, Düsseldorf Catholic Hospital Group, D-40591 Düsseldorf, Germany
| | - Christiane Habich
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, D-40225 Düsseldorf, Germany
| | - Volker Burkart
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, D-40225 Düsseldorf, Germany
- German Center for Diabetes Research (DZD), D-85764 München-Neuherberg, Germany
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172
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Abstract
Bacterial Hsp90 is an ATP-dependent molecular chaperone involved in protein remodeling and activation. The E. coli Hsp90, Hsp90Ec, collaborates in protein remodeling with another ATP-dependent chaperone, DnaK, the E. coli Hsp70. Both Hsp90Ec and DnaK hydrolyze ATP and client (substrate) proteins stimulate the hydrolysis. Additionally, ATP hydrolysis by the combination of Hsp90Ec and DnaK is synergistically stimulated in the presence of client (substrate). Here, we describe two steady-state ATPase assays used to monitor ATP hydrolysis by Hsp90Ec and DnaK as well as the synergistic stimulation of ATP hydrolysis by the combination of Hsp90Ec and DnaK in the presence of a client (substrate). The first assay is a spectrophotometric assay based on enzyme-coupled reactions that utilize the ADP formed during ATP hydrolysis to oxidize NADH. The second assay is a more sensitive method that directly quantifies the radioactive inorganic phosphate released following the hydrolysis of [γ-33P] ATP or [γ-32P] ATP.
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Affiliation(s)
- Joel R Hoskins
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 5144, NIH, Bethesda, MD, 20892, USA
| | - Sue Wickner
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 5144, NIH, Bethesda, MD, 20892, USA.
| | - Shannon M Doyle
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Room 5144, NIH, Bethesda, MD, 20892, USA.
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173
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Noormohammadi A, Calculli G, Gutierrez-Garcia R, Khodakarami A, Koyuncu S, Vilchez D. Mechanisms of protein homeostasis (proteostasis) maintain stem cell identity in mammalian pluripotent stem cells. Cell Mol Life Sci 2018; 75:275-290. [PMID: 28748323 PMCID: PMC11105389 DOI: 10.1007/s00018-017-2602-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 07/13/2017] [Accepted: 07/24/2017] [Indexed: 01/10/2023]
Abstract
Protein homeostasis, or proteostasis, is essential for cell function, development, and organismal viability. The composition of the proteome is adjusted to the specific requirements of a particular cell type and status. Moreover, multiple metabolic and environmental conditions challenge the integrity of the proteome. To maintain the quality of the proteome, the proteostasis network monitors proteins from their synthesis through their degradation. Whereas somatic stem cells lose their ability to maintain proteostasis with age, immortal pluripotent stem cells exhibit a stringent proteostasis network associated with their biological function and intrinsic characteristics. Moreover, growing evidence indicates that enhanced proteostasis mechanisms play a central role in immortality and cell fate decisions of pluripotent stem cells. Here, we will review new insights into the melding fields of proteostasis and pluripotency and their implications for the understanding of organismal development and survival.
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Affiliation(s)
- Alireza Noormohammadi
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - Giuseppe Calculli
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - Ricardo Gutierrez-Garcia
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - Amirabbas Khodakarami
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - Seda Koyuncu
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany.
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174
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Chtcheglova LA, Hinterdorfer P. Simultaneous AFM topography and recognition imaging at the plasma membrane of mammalian cells. Semin Cell Dev Biol 2018; 73:45-56. [DOI: 10.1016/j.semcdb.2017.08.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/04/2017] [Accepted: 08/08/2017] [Indexed: 10/19/2022]
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175
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Cesa LC, Shao H, Srinivasan SR, Tse E, Jain C, Zuiderweg ERP, Southworth DR, Mapp AK, Gestwicki JE. X-linked inhibitor of apoptosis protein (XIAP) is a client of heat shock protein 70 (Hsp70) and a biomarker of its inhibition. J Biol Chem 2017; 293:2370-2380. [PMID: 29255093 DOI: 10.1074/jbc.ra117.000634] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 11/28/2017] [Indexed: 11/06/2022] Open
Abstract
Heat shock protein 70 (Hsp70) and Hsp90 are molecular chaperones that play essential roles in tumor growth by stabilizing pro-survival client proteins. However, although the development of Hsp90 inhibitors has benefited from the identification of clients, such as Raf-1 proto-oncogene, Ser/Thr kinase (RAF1), that are particularly dependent on this chaperone, no equivalent clients for Hsp70 have been reported. Using chemical probes and MDA-MB-231 breast cancer cells, we found here that the inhibitors of apoptosis proteins, including c-IAP1 and X-linked inhibitor of apoptosis protein (XIAP), are obligate Hsp70 clients that are rapidly (within ∼3-12 h) lost after inhibition of Hsp70 but not of Hsp90. Mutagenesis and pulldown experiments revealed multiple Hsp70-binding sites on XIAP, suggesting that it is a direct, physical Hsp70 client. Interestingly, this interaction was unusually tight (∼260 nm) for an Hsp70-client interaction and involved non-canonical regions of the chaperone. Finally, we also found that Hsp70 inhibitor treatments caused loss of c-IAP1 and XIAP in multiple cancer cell lines and in tumor xenografts, but not in healthy cells. These results are expected to significantly accelerate Hsp70 drug discovery by providing XIAP as a pharmacodynamic biomarker. More broadly, our findings further suggest that Hsp70 and Hsp90 have partially non-overlapping sets of obligate protein clients in cancer cells.
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Affiliation(s)
| | - Hao Shao
- the Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, California 94158
| | | | - Eric Tse
- Biological Chemistry, and.,The Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109 and
| | | | | | - Daniel R Southworth
- From the Program in Chemical Biology.,Biological Chemistry, and.,The Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109 and
| | - Anna K Mapp
- From the Program in Chemical Biology.,The Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109 and.,Departments of Chemistry and
| | - Jason E Gestwicki
- the Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, California 94158
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176
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Brehme M, Voisine C. Model systems of protein-misfolding diseases reveal chaperone modifiers of proteotoxicity. Dis Model Mech 2017; 9:823-38. [PMID: 27491084 PMCID: PMC5007983 DOI: 10.1242/dmm.024703] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Chaperones and co-chaperones enable protein folding and degradation, safeguarding the proteome against proteotoxic stress. Chaperones display dynamic responses to exogenous and endogenous stressors and thus constitute a key component of the proteostasis network (PN), an intricately regulated network of quality control and repair pathways that cooperate to maintain cellular proteostasis. It has been hypothesized that aging leads to chronic stress on the proteome and that this could underlie many age-associated diseases such as neurodegeneration. Understanding the dynamics of chaperone function during aging and disease-related proteotoxic stress could reveal specific chaperone systems that fail to respond to protein misfolding. Through the use of suppressor and enhancer screens, key chaperones crucial for proteostasis maintenance have been identified in model organisms that express misfolded disease-related proteins. This review provides a literature-based analysis of these genetic studies and highlights prominent chaperone modifiers of proteotoxicity, which include the HSP70-HSP40 machine and small HSPs. Taken together, these studies in model systems can inform strategies for therapeutic regulation of chaperone functionality, to manage aging-related proteotoxic stress and to delay the onset of neurodegenerative diseases.
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Affiliation(s)
- Marc Brehme
- Joint Research Center for Computational Biomedicine (JRC-COMBINE), RWTH Aachen University, 52062 Aachen, Germany
| | - Cindy Voisine
- Department of Biology, Northeastern Illinois University, Chicago, IL 60625, USA
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177
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Amin-Wetzel N, Saunders RA, Kamphuis MJ, Rato C, Preissler S, Harding HP, Ron D. A J-Protein Co-chaperone Recruits BiP to Monomerize IRE1 and Repress the Unfolded Protein Response. Cell 2017; 171:1625-1637.e13. [PMID: 29198525 PMCID: PMC5733394 DOI: 10.1016/j.cell.2017.10.040] [Citation(s) in RCA: 157] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 10/04/2017] [Accepted: 10/25/2017] [Indexed: 12/29/2022]
Abstract
When unfolded proteins accumulate in the endoplasmic reticulum (ER), the unfolded protein response (UPR) increases ER-protein-folding capacity to restore protein-folding homeostasis. Unfolded proteins activate UPR signaling across the ER membrane to the nucleus by promoting oligomerization of IRE1, a conserved transmembrane ER stress receptor. However, the coupling of ER stress to IRE1 oligomerization and activation has remained obscure. Here, we report that the ER luminal co-chaperone ERdj4/DNAJB9 is a selective IRE1 repressor that promotes a complex between the luminal Hsp70 BiP and the luminal stress-sensing domain of IRE1α (IRE1LD). In vitro, ERdj4 is required for complex formation between BiP and IRE1LD. ERdj4 associates with IRE1LD and recruits BiP through the stimulation of ATP hydrolysis, forcibly disrupting IRE1 dimers. Unfolded proteins compete for BiP and restore IRE1LD to its default, dimeric, and active state. These observations establish BiP and its J domain co-chaperones as key regulators of the UPR. The endoplasmic reticulum co-chaperone ERdj4 selectively represses IRE1 signaling ERdj4 associates with the IRE1 luminal domain and recruits the Hsp70 BiP Recruited BiP hydrolyzes ATP to disrupt the active IRE1 luminal domain dimer Unfolded proteins compete for the repressive machinery to restore IRE1 dimers
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Affiliation(s)
- Niko Amin-Wetzel
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Reuben A Saunders
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Maarten J Kamphuis
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Claudia Rato
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Steffen Preissler
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Heather P Harding
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK.
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178
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Kelly M, McNeel D, Fisch P, Malkovsky M. Immunological considerations underlying heat shock protein-mediated cancer vaccine strategies. Immunol Lett 2017; 193:1-10. [PMID: 29129721 DOI: 10.1016/j.imlet.2017.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/01/2017] [Accepted: 11/05/2017] [Indexed: 12/31/2022]
Abstract
The success of active immunotherapies in the prevention of many infectious diseases over the course of over 200 years has lead scientists to wonder if the same principles could be applied to cancer. Antigen-specific active immunotherapies for the treatment of cancer have been researched for over two decades, however, the overwhelming majority of these studies have failed to stimulate robust clinical responses. It is clear that current active immunotherapy research should incorporate methods to increase the immunostimulatory capacity of these therapies. To directly address this need, we propose the addition of the immunostimulatory heat shock proteins (HSPs) to active immunotherapeutic strategies to augment their efficacy. Heat shock proteins are a family of highly conserved intracellular chaperone proteins, and are the most abundant family proteins inside cells. This ubiquity, and their robust immunostimulatory capacity, points to their importance in regulation of intracellular processes and, therefore, indicators of loss of cellular integrity if found extracellularly. Thus, we emphasize the importance of taking into consideration the location of vaccine-derived HSP/tumor-antigen complexes when designing active immunotheraputic strategies.
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Affiliation(s)
- Matthew Kelly
- Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Douglas McNeel
- University of Wisconsin Carbone Cancer Center, Madison, WI, USA; Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Paul Fisch
- Universitätsklinikum Freiburg, Institut für Pathologie, Freiburg, Germany
| | - Miroslav Malkovsky
- University of Wisconsin Carbone Cancer Center, Madison, WI, USA; Department of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
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179
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Broadening the functionality of a J-protein/Hsp70 molecular chaperone system. PLoS Genet 2017; 13:e1007084. [PMID: 29084221 PMCID: PMC5679652 DOI: 10.1371/journal.pgen.1007084] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 11/09/2017] [Accepted: 10/18/2017] [Indexed: 12/21/2022] Open
Abstract
By binding to a multitude of polypeptide substrates, Hsp70-based molecular chaperone systems perform a range of cellular functions. All J-protein co-chaperones play the essential role, via action of their J-domains, of stimulating the ATPase activity of Hsp70, thereby stabilizing its interaction with substrate. In addition, J-proteins drive the functional diversity of Hsp70 chaperone systems through action of regions outside their J-domains. Targeting to specific locations within a cellular compartment and binding of specific substrates for delivery to Hsp70 have been identified as modes of J-protein specialization. To better understand J-protein specialization, we concentrated on Saccharomyces cerevisiae SIS1, which encodes an essential J-protein of the cytosol/nucleus. We selected suppressors that allowed cells lacking SIS1 to form colonies. Substitutions changing single residues in Ydj1, a J-protein, which, like Sis1, partners with Hsp70 Ssa1, were isolated. These gain-of-function substitutions were located at the end of the J-domain, suggesting that suppression was connected to interaction with its partner Hsp70, rather than substrate binding or subcellular localization. Reasoning that, if YDJ1 suppressors affect Ssa1 function, substitutions in Hsp70 itself might also be able to overcome the cellular requirement for Sis1, we carried out a selection for SSA1 suppressor mutations. Suppressing substitutions were isolated that altered sites in Ssa1 affecting the cycle of substrate interaction. Together, our results point to a third, additional means by which J-proteins can drive Hsp70's ability to function in a wide range of cellular processes-modulating the Hsp70-substrate interaction cycle.
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180
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Preissler S, Rohland L, Yan Y, Chen R, Read RJ, Ron D. AMPylation targets the rate-limiting step of BiP's ATPase cycle for its functional inactivation. eLife 2017; 6:29428. [PMID: 29064368 PMCID: PMC5667935 DOI: 10.7554/elife.29428] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 10/22/2017] [Indexed: 12/21/2022] Open
Abstract
The endoplasmic reticulum (ER)-localized Hsp70 chaperone BiP contributes to protein folding homeostasis by engaging unfolded client proteins in a process that is tightly coupled to ATP binding and hydrolysis. The inverse correlation between BiP AMPylation and the burden of unfolded ER proteins suggests a post-translational mechanism for adjusting BiP's activity to changing levels of ER stress, but the underlying molecular details are unexplored. We present biochemical and crystallographic studies indicating that irrespective of the identity of the bound nucleotide AMPylation biases BiP towards a conformation normally attained by the ATP-bound chaperone. AMPylation does not affect the interaction between BiP and J-protein co-factors but appears to allosterically impair J protein-stimulated ATP-hydrolysis, resulting in the inability of modified BiP to attain high affinity for its substrates. These findings suggest a molecular mechanism by which AMPylation serves as a switch to inactivate BiP, limiting its interactions with substrates whilst conserving ATP.
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Affiliation(s)
- Steffen Preissler
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Lukas Rohland
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Yahui Yan
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Ruming Chen
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Randy J Read
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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181
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Wieteska L, Shahidi S, Zhuravleva A. Allosteric fine-tuning of the conformational equilibrium poises the chaperone BiP for post-translational regulation. eLife 2017; 6:29430. [PMID: 29064369 PMCID: PMC5655141 DOI: 10.7554/elife.29430] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 09/01/2017] [Indexed: 12/12/2022] Open
Abstract
BiP is the only Hsp70 chaperone in the endoplasmic reticulum (ER) and similar to other Hsp70s, its activity relies on nucleotide- and substrate-controllable docking and undocking of its nucleotide-binding domain (NBD) and substrate-binding domain (SBD). However, little is known of specific features of the BiP conformational landscape that tune BiP to its unique tasks and the ER environment. We present methyl NMR analysis of the BiP chaperone cycle that reveals surprising conformational heterogeneity of ATP-bound BiP that distinguishes BiP from its bacterial homologue DnaK. This unusual poise enables gradual post-translational regulation of the BiP chaperone cycle and its chaperone activity by subtle local perturbations at SBD allosteric 'hotspots'. In particular, BiP inactivation by AMPylation of its SBD does not disturb Hsp70 inter-domain allostery and preserves BiP structure. Instead it relies on a redistribution of the BiP conformational ensemble and stabilization the domain-docked conformation in presence of ADP and ATP.
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Affiliation(s)
- Lukasz Wieteska
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Saeid Shahidi
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Anastasia Zhuravleva
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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182
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Sekhar A, Nagesh J, Rosenzweig R, Kay LE. Conformational heterogeneity in the Hsp70 chaperone-substrate ensemble identified from analysis of NMR-detected titration data. Protein Sci 2017; 26:2207-2220. [PMID: 28833766 DOI: 10.1002/pro.3276] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 08/17/2017] [Indexed: 01/06/2023]
Abstract
The Hsp70 chaperone system plays a critical role in cellular homeostasis by binding to client protein molecules. We have recently shown by methyl-TROSY NMR methods that the Escherichia coli Hsp70, DnaK, can form multiple bound complexes with a small client protein, hTRF1. In an effort to characterize the interactions further we report here the results of an NMR-based titration study of hTRF1 and DnaK, where both molecular components are monitored simultaneously, leading to a binding model. A central finding is the formation of a previously undetected 3:1 hTRF1-DnaK complex, suggesting that under heat shock conditions, DnaK might be able to protect cytosolic proteins whose net concentrations would exceed that of the chaperone. Moreover, these results provide new insight into the heterogeneous ensemble of complexes formed by DnaK chaperones and further emphasize the unique role of NMR spectroscopy in obtaining information about individual events in a complex binding scheme by exploiting a large number of probes that report uniquely on distinct binding processes.
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Affiliation(s)
- Ashok Sekhar
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Jayashree Nagesh
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6, Canada
| | - Rina Rosenzweig
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.,Department of Structural Biology, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Lewis E Kay
- Departments of Molecular Genetics, Biochemistry and Chemistry, University of Toronto, Toronto, Ontario, M5S 1A8, Canada.,Program in Molecular Medicine, 555 University Avenue, Hospital for Sick Children, Toronto, Ontario, M5G 1X8, Canada
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183
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Dutkiewicz R, Nowak M, Craig EA, Marszalek J. Fe-S Cluster Hsp70 Chaperones: The ATPase Cycle and Protein Interactions. Methods Enzymol 2017; 595:161-184. [PMID: 28882200 DOI: 10.1016/bs.mie.2017.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hsp70 chaperones and their obligatory J-protein cochaperones function together in many cellular processes. Via cycles of binding to short stretches of exposed amino acids on substrate proteins, Hsp70/J-protein chaperones not only facilitate protein folding but also drive intracellular protein transport, biogenesis of cellular structures, and disassembly of protein complexes. The biogenesis of iron-sulfur (Fe-S) clusters is one of the critical cellular processes that require Hsp70/J-protein action. Fe-S clusters are ubiquitous cofactors critical for activity of proteins performing diverse functions in, for example, metabolism, RNA/DNA transactions, and environmental sensing. This biogenesis process can be divided into two sequential steps: first, the assembly of an Fe-S cluster on a conserved scaffold protein, and second, the transfer of the cluster from the scaffold to a recipient protein. The second step involves Hsp70/J-protein chaperones. Via binding to the scaffold, chaperones enable cluster transfer to recipient proteins. In eukaryotic cells mitochondria have a key role in Fe-S cluster biogenesis. In this review, we focus on methods that enabled us to dissect protein interactions critical for the function of Hsp70/J-protein chaperones in the mitochondrial process of Fe-S cluster biogenesis in the yeast Saccharomyces cerevisiae.
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Affiliation(s)
- Rafal Dutkiewicz
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Malgorzata Nowak
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | | | - Jaroslaw Marszalek
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland; University of Wisconsin-Madison, Madison, WI, United States.
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184
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Nguyen B, Hartich D, Seifert U, Rios PDL. Thermodynamic Bounds on the Ultra- and Infra-affinity of Hsp70 for Its Substrates. Biophys J 2017; 113:362-370. [PMID: 28746847 DOI: 10.1016/j.bpj.2017.06.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/31/2017] [Accepted: 06/09/2017] [Indexed: 12/16/2022] Open
Abstract
The 70 kDa heat shock protein Hsp70 has several essential functions in living systems, such as protecting cells against protein aggregation, assisting protein folding, remodeling protein complexes, and driving translocation into organelles. These functions require high affinity for nonspecific amino acid sequences that are ubiquitous in proteins. It has been recently shown that this high affinity, called ultra-affinity, depends on a process driven out of equilibrium by ATP hydrolysis. Here, we establish the thermodynamic bounds for ultra-affinity, and further show that the same reaction scheme can in principle be used both to strengthen and to weaken affinities (leading in this case to infra-affinity). We show that cofactors are essential to achieve affinity beyond the equilibrium range. Finally, biological implications are discussed.
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Affiliation(s)
- Basile Nguyen
- II. Institut für Theoretische Physik, Universität Stuttgart, Stuttgart, Germany; Laboratory of Statistical Biophysics, Institute of Physics, School of Basic Science and Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - David Hartich
- II. Institut für Theoretische Physik, Universität Stuttgart, Stuttgart, Germany
| | - Udo Seifert
- II. Institut für Theoretische Physik, Universität Stuttgart, Stuttgart, Germany
| | - Paolo De Los Rios
- Laboratory of Statistical Biophysics, Institute of Physics, School of Basic Science and Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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185
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Wang LC, Liao LX, Lv HN, Liu D, Dong W, Zhu J, Chen JF, Shi ML, Fu G, Song XM, Jiang Y, Zeng KW, Tu PF. Highly Selective Activation of Heat Shock Protein 70 by Allosteric Regulation Provides an Insight into Efficient Neuroinflammation Inhibition. EBioMedicine 2017; 23:160-172. [PMID: 28807514 PMCID: PMC5605382 DOI: 10.1016/j.ebiom.2017.08.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 08/06/2017] [Accepted: 08/07/2017] [Indexed: 12/11/2022] Open
Abstract
Heat shock protein 70 (Hsp70) is widely involved in immune disorders, making it as an attractive drug target for inflammation diseases. Nonselective induction of Hsp70 upregulation for inflammation therapy could cause extensive interference in inflammation-unrelated protein functions, potentially resulting in side effects. Nevertheless, direct pharmacological activation of Hsp70 via targeting specific functional amino acid residue may provide an insight into precise Hsp70 function regulation and a more satisfactory treatment effect for inflammation, which has not been extensively focused. Here we show a cysteine residue (Cys306) for selective Hsp70 activation using natural small-molecule handelin. Covalent modification of Cys306 significantly elevates Hsp70 activity and shows more satisfactory anti-neuroinflammation effects. Mechanism study reveals Cys306 modification by handelin induces an allosteric regulation to facilitate adenosine triphosphate hydrolysis capacity of Hsp70, which leads to the effective blockage of subsequent inflammation signaling pathway. Collectively, our study offers some insights into direct pharmacological activation of Hsp70 by specially targeting functional cysteine residue, thus providing a powerful tool for accurately modulating neuroinflammation pathogenesis in human with fewer undesirable adverse effects. Cys306 is a druggable residue for direct pharmacological activation of Hsp70. Covalent modification of Cys306 promotes direct Hsp70 activation via allosteric effect. Pharmacological activation of Hsp70 exerts satisfactory inhibition on neuroinflammation with fewer side effects.
Accumulated evidence reveals that Hsp70, a stress response protein, is highly involved in various neuroimmunological diseases. Hsp70 herein serves as a tempting target for anti-inflammation therapy. In this work, we identified an herb-derived guaianolide dimer compound handelin as a potent activator of Hsp70 with anti-neuroinflammatory effects. Handelin covalently modified Cys306 residue of Hsp70, and then activated Hsp70 by allosteric effect. These results can provide an insight into the direct pharmacological regulation of Hsp70 function by targeting specific amino acid residue and also guide future rational drug design to treat human neuroimmunological diseases.
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Affiliation(s)
- Li-Chao Wang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Li-Xi Liao
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Hai-Ning Lv
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Dan Liu
- Proteomics Laboratory, Medical and Healthy Analytical Center, Peking University Health Science Center, Beijing 100191, China
| | - Wei Dong
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Jian Zhu
- State Key Laboratory of Membrane Biology, Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China
| | - Jin-Feng Chen
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Meng-Ling Shi
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Ge Fu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Xiao-Min Song
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Yong Jiang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Ke-Wu Zeng
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
| | - Peng-Fei Tu
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, China.
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186
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Yu D, Lv L, Fang L, Zhang B, Wang J, Zhan G, Zhao L, Zhao X, Li B. Inhibitory effects and mechanism of dihydroberberine on hERG channels expressed in HEK293 cells. PLoS One 2017; 12:e0181823. [PMID: 28763460 PMCID: PMC5538702 DOI: 10.1371/journal.pone.0181823] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/09/2017] [Indexed: 12/20/2022] Open
Abstract
The human ether-a-go-go-related gene (hERG) potassium channel conducts rapid delayed rectifier potassium currents (IKr) and contributes to phase III cardiac action potential repolarization. Drugs inhibit hERG channels by binding to aromatic residues in hERG helixes. Berberine (BBR) has multiple actions, and its hydrogenated derivative dihydroberberine (DHB) is a potential candidate for developing new drugs. Previous studies have demonstrated that BBR blocks hERG channels and prolongs action potential duration (APD). Our present study aimed to investigate the effects and mechanism of DHB on hERG channels. Protein expression and the hERG current were analyzed using western blotting and patch-clamp, respectively. DHB inhibited the hERG current concentration-dependently after instantaneous perfusion, accelerated channel inactivation by directly binding tyrosine (Tyr652) and phenylalanine (Phe656), and decreased mature (155-kDa) and simultaneously increased immature (135-kDa) hERG expression, respectively. This suggests disruption of forward trafficking of hERG channels. Besides, DHB remarkably reduced heat shock protein 90 (Hsp90) expression and its interaction with hERG, indicating that DHB disrupted hERG trafficking by impairing channel folding. Meanwhie, DHB enhanced the expression of cleaved activating transcription factor-6 (ATF-6), a biomarker of unfolded protein response (UPR). Expression of calnexin and calreticulin, chaperones activated by ATF-6 to facilitate channel folding, were also increased, which indicating UPR activation. Additionally, the degradation rate of mature 155-kDa hERG increased following DHB exposure. In conclusion, we demonstrated that DHB acutely blocked hERG channels by binding the aromatic Tyr652 and Phe656. DHB may decrease hERG plasma membrane expression through two pathways involving disruption of forward trafficking of immature hERG channels and enhanced degradation of mature hERG channels. Furthermore, forward trafficking was disrupted by impaired channel folding associated with altered interactions between hERG proteins and chaperones. Finally, trafficking inhibition activated UPR, and mature hERG channel degradation was increased by DHB.
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Affiliation(s)
- Dahai Yu
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
| | - Lin Lv
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
| | - Li Fang
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
| | - Bo Zhang
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
| | - Junnan Wang
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
| | - Ge Zhan
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
| | - Lei Zhao
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
| | - Xin Zhao
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
| | - Baoxin Li
- Department of Pharmacology, College of Pharmacy, Harbin Medical University, Harbin, Heilongjiang Province, People's Republic of China
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187
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Clark PL, Elcock AH. Molecular chaperones: providing a safe place to weather a midlife protein-folding crisis. Nat Struct Mol Biol 2017; 23:621-3. [PMID: 27384188 DOI: 10.1038/nsmb.3255] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Patricia L Clark
- Department of Chemistry &Biochemistry and the Department of Chemical &Biomolecular Engineering, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Adrian H Elcock
- Department of Biochemistry, University of Iowa, Iowa City, Iowa, USA
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188
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Jiang JF, Lei F, Yuan ZY, Wang YG, Wang XP, Yan XJ, Yu X, Xing DM, DU LJ. Mechanism underlying berberine's effects on HSP70/TNFα under heat stress: Correlation with the TATA boxes. Chin J Nat Med 2017; 15:178-191. [PMID: 28411686 DOI: 10.1016/s1875-5364(17)30034-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Indexed: 11/19/2022]
Abstract
Heat stress can stimulate an increase in body temperature, which is correlated with increased expression of heat shock protein 70 (HSP70) and tumor necrosis factor α (TNFα). The exact mechanism underlying the HSP70 and TNFα induction is unclear. Berberine (BBR) can significantly inhibit the temperature rise caused by heat stress, but the mechanism responsible for the BBR effect on HSP70 and TNFα signaling has not been investigated. The aim of the present study was to explore the relationship between the expression of HSP70 and TNFα and the effects of BBR under heat conditions, using in vivo and in vitro models. The expression levels of HSP70 and TNFα were determined using RT-PCR and Western blotting analyses. The results showed that the levels of HSP70 and TNFα were up-regulated under heat conditions (40 °C). HSP70 acted as a chaperone to maintain TNFα homeostasis with rising the temperature, but knockdown of HSP70 could not down-regulate the level of TNFα. Furthermore, TNFα could not influence the expression of HSP70 under normal and heat conditions. BBR targeted both HSP70 and TNFα by suppressing their gene transcription, thereby decreasing body temperature under heat conditions. In conclusion, BBR has a potential to be developed as a therapeutic strategy for suppressing the thermal effects in hot environments.
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Affiliation(s)
- Jing-Fei Jiang
- MOE (Ministry of Education) Key Laboratory of Protein Sciences, Laboratory of Molecular Pharmacology and Pharmaceutical Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Fan Lei
- Department of Pharmacology and Pharmaceutical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Zhi-Yi Yuan
- MOE (Ministry of Education) Key Laboratory of Protein Sciences, Laboratory of Molecular Pharmacology and Pharmaceutical Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yu-Gang Wang
- MD Anderson Cancer Center, University of Texas, Houston, TX 77030, USA
| | - Xin-Pei Wang
- MOE (Ministry of Education) Key Laboratory of Protein Sciences, Laboratory of Molecular Pharmacology and Pharmaceutical Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiao-Jin Yan
- MOE (Ministry of Education) Key Laboratory of Protein Sciences, Laboratory of Molecular Pharmacology and Pharmaceutical Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xuan Yu
- MOE (Ministry of Education) Key Laboratory of Protein Sciences, Laboratory of Molecular Pharmacology and Pharmaceutical Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dong-Ming Xing
- MOE (Ministry of Education) Key Laboratory of Protein Sciences, Laboratory of Molecular Pharmacology and Pharmaceutical Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Li-Jun DU
- MOE (Ministry of Education) Key Laboratory of Protein Sciences, Laboratory of Molecular Pharmacology and Pharmaceutical Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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189
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Fernández-Fernández MR, Gragera M, Ochoa-Ibarrola L, Quintana-Gallardo L, Valpuesta JM. Hsp70 - a master regulator in protein degradation. FEBS Lett 2017; 591:2648-2660. [PMID: 28696498 DOI: 10.1002/1873-3468.12751] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 07/04/2017] [Accepted: 07/07/2017] [Indexed: 12/31/2022]
Abstract
Proteostasis, the controlled balance of protein synthesis, folding, assembly, trafficking and degradation, is a paramount necessity for cell homeostasis. Impaired proteostasis is a hallmark of ageing and of many human diseases. Molecular chaperones are essential for proteostasis in eukaryotic cells, and their function has traditionally been linked to protein folding, assembly and disaggregation. More recent findings suggest that chaperones also contribute to key steps in protein degradation. In particular, Hsp70 has an essential role in substrate degradation through the ubiquitin-proteasome system, as well as through different autophagy pathways. Accumulated knowledge suggests that the fate of an Hsp70 substrate is dictated by the combination of partners (cochaperones and other chaperones) that interact with Hsp70 in a given cell context.
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Affiliation(s)
| | - Marcos Gragera
- Centro Nacional de Biotecnología (CNB-CSIC), Madrid, Spain
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190
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Keefer KM, True HL. A toxic imbalance of Hsp70s in Saccharomyces cerevisiae is caused by competition for cofactors. Mol Microbiol 2017; 105:860-868. [PMID: 28665048 DOI: 10.1111/mmi.13741] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 06/26/2017] [Accepted: 06/27/2017] [Indexed: 01/28/2023]
Abstract
Molecular chaperones are responsible for managing protein folding from translation through degradation. These crucial machines ensure that protein homeostasis is optimally maintained for cell health. However, 'too much of a good thing' can be deadly, and the excess of chaperones can be toxic under certain cellular conditions. For example, overexpression of Ssa1, a yeast Hsp70, is toxic to cells in folding-challenged states such as [PSI+]. We discovered that overexpression of the nucleotide exchange factor Sse1 can partially alleviate this toxicity. We further argue that the basis of the toxicity is related to the availability of Hsp70 cofactors, such as Hsp40 J-proteins and nucleotide exchange factors. Ultimately, our work informs future studies about functional chaperone balance and cautions against therapeutic chaperone modifications without a thorough examination of cofactor relationships.
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Affiliation(s)
- Kathryn M Keefer
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Heather L True
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
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191
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Lopez CE, Sheehan HC, Vierra DA, Azzinaro PA, Meedel TH, Howlett NG, Irvine SQ. Proteomic responses to elevated ocean temperature in ovaries of the ascidian Ciona intestinalis. Biol Open 2017; 6:943-955. [PMID: 28500033 PMCID: PMC5550911 DOI: 10.1242/bio.024786] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 05/10/2017] [Indexed: 11/21/2022] Open
Abstract
Ciona intestinalis, a common sea squirt, exhibits lower reproductive success at the upper extreme of the water temperatures it experiences in coastal New England. In order to understand the changes in protein expression associated with elevated temperatures, and possible response to global temperature change, we reared C. intestinalis from embryos to adults at 18°C (a temperature at which they reproduce normally at our collection site in Rhode Island) and 22°C (the upper end of the local temperature range). We then dissected ovaries from animals at each temperature, extracted protein, and measured proteomic levels using shotgun mass spectrometry (LC-MS/MS). 1532 proteins were detected at a 1% false discovery rate present in both temperature groups by our LC-MS/MS method. 62 of those proteins are considered up- or down-regulated according to our statistical criteria. Principal component analysis shows a clear distinction in protein expression pattern between the control (18°C) group and high temperature (22°C) group. Similar to previous studies, cytoskeletal and chaperone proteins are upregulated in the high temperature group. Unexpectedly, we find evidence that proteolysis is downregulated at the higher temperature. We propose a working model for the high temperature response in C. intestinalis ovaries whereby increased temperature induces upregulation of signal transduction pathways involving PTPN11 and CrkL, and activating coordinated changes in the proteome especially in large lipid transport proteins, cellular stress responses, cytoskeleton, and downregulation of energy metabolism.
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Affiliation(s)
- Chelsea E Lopez
- Departments of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - Hannah C Sheehan
- Departments of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
| | - David A Vierra
- Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Paul A Azzinaro
- Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Thomas H Meedel
- Biology Department, Rhode Island College, Providence, RI 02908, USA
| | - Niall G Howlett
- Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA
| | - Steven Q Irvine
- Departments of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
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192
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Rosenzweig R, Sekhar A, Nagesh J, Kay LE. Promiscuous binding by Hsp70 results in conformational heterogeneity and fuzzy chaperone-substrate ensembles. eLife 2017; 6. [PMID: 28708484 PMCID: PMC5511010 DOI: 10.7554/elife.28030] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2017] [Accepted: 06/28/2017] [Indexed: 01/05/2023] Open
Abstract
The Hsp70 chaperone system is integrated into a myriad of biochemical processes that are critical for cellular proteostasis. Although detailed pictures of Hsp70 bound with peptides have emerged, correspondingly detailed structural information on complexes with folding-competent substrates remains lacking. Here we report a methyl-TROSY based solution NMR study showing that the Escherichia coli version of Hsp70, DnaK, binds to as many as four distinct sites on a small 53-residue client protein, hTRF1. A fraction of hTRF1 chains are also bound to two DnaK molecules simultaneously, resulting in a mixture of DnaK-substrate sub-ensembles that are structurally heterogeneous. The interactions of Hsp70 with a client protein at different sites results in a fuzzy chaperone-substrate ensemble and suggests a mechanism for Hsp70 function whereby the structural heterogeneity of released substrate molecules enables them to circumvent kinetic traps in their conformational free energy landscape and fold efficiently to the native state. DOI:http://dx.doi.org/10.7554/eLife.28030.001
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Affiliation(s)
- Rina Rosenzweig
- Department of Molecular Genetics, The University of Toronto, Toronto, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Ashok Sekhar
- Department of Molecular Genetics, The University of Toronto, Toronto, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada
| | - Jayashree Nagesh
- Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Canada
| | - Lewis E Kay
- Department of Molecular Genetics, The University of Toronto, Toronto, Canada.,Department of Biochemistry, The University of Toronto, Toronto, Canada.,Department of Chemistry, University of Toronto, Toronto, Canada.,Hospital for Sick Children, Program in Molecular Structure and Function, Toronto, Canada
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193
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Magesky A, de Oliveira Ribeiro CA, Beaulieu L, Pelletier É. Silver nanoparticles and dissolved silver activate contrasting immune responses and stress-induced heat shock protein expression in sea urchin. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2017; 36:1872-1886. [PMID: 27943424 DOI: 10.1002/etc.3709] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 09/14/2016] [Accepted: 12/08/2016] [Indexed: 06/06/2023]
Abstract
Using immune cells of sea urchin Strongylocentrotus droebachiensis in early development as a model, the cellular protective mechanisms against ionic and poly(allylamine)-coated silver nanoparticle (AgNPs; 14 ± 6 nm) treatments at 100 μg L-1 were investigated. Oxidative stress, heat shock protein expression, and pigment production by spherulocytes were determined as well as AgNP translocation pathways and their multiple effects on circulating coelomocytes. Sea urchins showed an increasing resilience to Ag over time because ionic Ag is accumulated in a steady way, although nanoAg levels dropped between 48 h and 96 h. A clotting reaction emerged on tissues injured by dissolved Ag (present as chloro-complexes in seawater) between 12 h and 48 h. Silver contamination and nutritional state influenced the production of reactive oxygen species. After passing through coelomic sinuses and gut, AgNPs were found in coelomocytes. Inside blood vessels, apoptosis-like processes appeared in coelomocytes highly contaminated by poly(allylamine)-coated AgNPs. Increasing levels of Ag accumulated by urchins once exposed to AgNPs pointed to a Trojan-horse mechanism operating over 12-d exposure. However, under short-term treatments, physical interactions of poly(allylamine)-coated AgNPs with cell structures might be, at some point, predominant and responsible for the highest levels of stress-related proteins detected. The present study is the first report detailing nano-translocation in a marine organism and multiple mechanisms by which sea urchin cells can deal with toxic AgNPs. Environ Toxicol Chem 2017;36:1872-1886. © 2016 SETAC.
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Affiliation(s)
- Adriano Magesky
- Institut de sciences de la mer de Rimouski, Université du Québec à Rimouski, Rimouski, Québec, Canada
| | | | - Lucie Beaulieu
- Département des sciences des aliments, Université Laval, Québec, Québec, Canada
| | - Émilien Pelletier
- Institut de sciences de la mer de Rimouski, Université du Québec à Rimouski, Rimouski, Québec, Canada
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194
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Protein quality control at the mitochondrion. Essays Biochem 2017; 60:213-225. [PMID: 27744337 DOI: 10.1042/ebc20160009] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/31/2016] [Indexed: 12/17/2022]
Abstract
Mitochondria are essential constituents of a eukaryotic cell by supplying ATP and contributing to many mayor metabolic processes. As endosymbiotic organelles, they represent a cellular subcompartment exhibiting many autonomous functions, most importantly containing a complete endogenous machinery responsible for protein expression, folding and degradation. This article summarizes the biochemical processes and the enzymatic components that are responsible for maintaining mitochondrial protein homoeostasis. As mitochondria lack a large part of the required genetic information, most proteins are synthesized in the cytosol and imported into the organelle. After reaching their destination, polypeptides must fold and assemble into active proteins. Under pathological conditions, mitochondrial proteins become misfolded or damaged and need to be repaired with the help of molecular chaperones or eventually removed by specific proteases. Failure of these protein quality control mechanisms results in loss of mitochondrial function and structural integrity. Recently, novel mechanisms have been identified that support mitochondrial quality on the organellar level. A mitochondrial unfolded protein response allows the adaptation of chaperone and protease activities. Terminally damaged mitochondria may be removed by a variation of autophagy, termed mitophagy. An understanding of the role of protein quality control in mitochondria is highly relevant for many human pathologies, in particular neurodegenerative diseases.
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195
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Koldewey P, Horowitz S, Bardwell JCA. Chaperone-client interactions: Non-specificity engenders multifunctionality. J Biol Chem 2017; 292:12010-12017. [PMID: 28620048 DOI: 10.1074/jbc.r117.796862] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Here, we provide an overview of the different mechanisms whereby three different chaperones, Spy, Hsp70, and Hsp60, interact with folding proteins, and we discuss how these chaperones may guide the folding process. Available evidence suggests that even a single chaperone can use many mechanisms to aid in protein folding, most likely due to the need for most chaperones to bind clients promiscuously. Chaperone mechanism may be better understood by always considering it in the context of the client's folding pathway and biological function.
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Affiliation(s)
- Philipp Koldewey
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - Scott Horowitz
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109
| | - James C A Bardwell
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan 48109.
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196
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Penkler D, Sensoy Ö, Atilgan C, Tastan Bishop Ö. Perturbation-Response Scanning Reveals Key Residues for Allosteric Control in Hsp70. J Chem Inf Model 2017; 57:1359-1374. [PMID: 28505454 DOI: 10.1021/acs.jcim.6b00775] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Hsp70 molecular chaperones play an important role in maintaining cellular homeostasis, and are implicated in a wide array of cellular processes, including protein recovery from aggregates, cross-membrane protein translocation, and protein biogenesis. Hsp70 consists of two domains, a nucleotide binding domain (NBD) and a substrate binding domain (SBD), each of which communicates via an allosteric mechanism such that the protein interconverts between two functional states, an ATP-bound open conformation and an ADP-bound closed conformation. The exact mechanism for interstate conversion is not as yet fully understood. However, the ligand-bound states of the NBD and SBD as well as interactions with cochaperones such as DnaJ and nucleotide exchange factor are thought to play crucial regulatory roles. In this study, we apply the perturbation-response scanning (PRS) method in combination with molecular dynamics simulations as a computational tool for the identification of allosteric hot residues in the large multidomain Hsp70 protein. We find evidence in support of the hypothesis that substrate binding triggers ATP hydrolysis and that the ADP-substrate complex favors interstate conversion to the closed state. Furthermore, our data are in agreement with the proposal that there is an allosterically active intermediate state between the open and closed states and vice versa, as we find evidence that ATP binding to the closed structure and peptide binding to the open structure allosterically "activate" the respective complexes. We conclude our analysis by showing how our PRS data fit the current opinion on the Hsp70 conformational cycle and present several allosteric hot residues that may provide a platform for further studies to gain additional insight into Hsp70 allostery.
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Affiliation(s)
- David Penkler
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University , Grahamstown 6140, South Africa
| | - Özge Sensoy
- School of Engineering and Natural Sciences, Istanbul Medipol University , Beykoz 34810, Istanbul, Turkey
| | - Canan Atilgan
- Faculty of Engineering and Natural Sciences, Sabanci University , Tuzla 34956, Istanbul, Turkey
| | - Özlem Tastan Bishop
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University , Grahamstown 6140, South Africa
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197
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Abstract
The carboxyl terminal of Hsp70-interacting protein (CHIP) is an E3 ubiquitin ligase that plays a pivotal role in the protein quality control system by shifting the balance of the folding-refolding machinery toward the degradative pathway. However, the precise mechanisms by which nonnative proteins are selected for degradation by CHIP either directly or indirectly via chaperone Hsp70 or Hsp90 are still not clear. In this review, we aim to provide a comprehensive model of the mechanism by which CHIP degrades its substrate in a chaperone-dependent or direct manner. In addition, through tight regulation of the protein level of its substrates, CHIP plays important roles in many physiological and pathological conditions, including cancers, neurological disorders, cardiac diseases, bone metabolism, immunity, and so on. Nonetheless, the precise mechanisms underlying the regulation of the immune system by CHIP are still poorly understood despite accumulating developments in our understanding of the regulatory roles of CHIP in both innate and adaptive immune responses. In this review, we also aim to provide a view of CHIP-mediated regulation of immune responses and the signaling pathways involved in the model described. Finally, we discuss the roles of CHIP in immune-related diseases.
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Affiliation(s)
- Shaohua Zhan
- a Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences , National Key Laboratory of Medical Molecular Biology & Department of Immunology , Dongcheng District , Beijing , China
| | - Tianxiao Wang
- b Key Laboratory of Carcinogenesis and Translational Research, Department of Head and Neck Surgery , Peking University Cancer Hospital & Institute , Beijing , China
| | - Wei Ge
- a Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences , National Key Laboratory of Medical Molecular Biology & Department of Immunology , Dongcheng District , Beijing , China
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198
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Garcia VM, Nillegoda NB, Bukau B, Morano KA. Substrate binding by the yeast Hsp110 nucleotide exchange factor and molecular chaperone Sse1 is not obligate for its biological activities. Mol Biol Cell 2017; 28:2066-2075. [PMID: 28539411 PMCID: PMC5509420 DOI: 10.1091/mbc.e17-01-0070] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/15/2017] [Accepted: 05/17/2017] [Indexed: 02/05/2023] Open
Abstract
The highly conserved heat shock protein 70 (Hsp70) is a ubiquitous molecular chaperone essential for maintaining cellular protein homeostasis. The related protein Hsp110 (Sse1/Sse2 in Saccharomyces cerevisiae) functions as a nucleotide exchange factor (NEF) to regulate the protein folding activity of Hsp70. Hsp110/Sse1 also can prevent protein aggregation in vitro via its substrate-binding domain (SBD), but the cellular roles of this "holdase" activity are poorly defined. We generated and characterized an Sse1 mutant that separates, for the first time, its nucleotide exchange and substrate-binding functions. Sse1sbd retains nucleotide-binding and nucleotide exchange activities while exhibiting severe deficiencies in chaperone holdase activity for unfolded polypeptides. In contrast, we observed no effect of the SBD mutation in reconstituted disaggregation or refolding reactions in vitro. In vivo, Sse1sbd successfully heterodimerized with the yeast cytosolic Hsp70s Ssa and Ssb and promoted normal growth, with the exception of sensitivity to prolonged heat but not other proteotoxic stress. Moreover, Sse1sbd was fully competent to support Hsp90-dependent signaling through heterologously expressed glucocorticoid receptor and degradation of a permanently misfolded protein, two previously defined roles for Sse1. We conclude that despite conservation among eukaryotic homologues, chaperone holdase activity is not an obligate function in the Hsp110 family.
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Affiliation(s)
- Veronica M Garcia
- Department of Microbiology and Molecular Genetics, University of Texas McGovern Medical School at Houston, Houston, TX 77030.,MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, TX 77030
| | - Nadinath B Nillegoda
- Center for Molecular Biology of Heidelberg University and German Cancer Research Center, D-69120 Heidelberg, Germany
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University and German Cancer Research Center, D-69120 Heidelberg, Germany
| | - Kevin A Morano
- Department of Microbiology and Molecular Genetics, University of Texas McGovern Medical School at Houston, Houston, TX 77030
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199
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Nanomechanics of the substrate binding domain of Hsp70 determine its allosteric ATP-induced conformational change. Proc Natl Acad Sci U S A 2017; 114:6040-6045. [PMID: 28533394 DOI: 10.1073/pnas.1619843114] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Owing to the cooperativity of protein structures, it is often almost impossible to identify independent subunits, flexible regions, or hinges simply by visual inspection of static snapshots. Here, we use single-molecule force experiments and simulations to apply tension across the substrate binding domain (SBD) of heat shock protein 70 (Hsp70) to pinpoint mechanical units and flexible hinges. The SBD consists of two nanomechanical units matching 3D structural parts, called the α- and β-subdomain. We identified a flexible region within the rigid β-subdomain that gives way under load, thus opening up the α/β interface. In exactly this region, structural changes occur in the ATP-induced opening of Hsp70 to allow substrate exchange. Our results show that the SBD's ability to undergo large conformational changes is already encoded by passive mechanics of the individual elements.
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200
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Gorenberg EL, Chandra SS. The Role of Co-chaperones in Synaptic Proteostasis and Neurodegenerative Disease. Front Neurosci 2017; 11:248. [PMID: 28579939 PMCID: PMC5437171 DOI: 10.3389/fnins.2017.00248] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 04/18/2017] [Indexed: 12/14/2022] Open
Abstract
Synapses must be preserved throughout an organism's lifespan to allow for normal brain function and behavior. Synapse maintenance is challenging given the long distances between the termini and the cell body, reliance on axonal transport for delivery of newly synthesized presynaptic proteins, and high rates of synaptic vesicle exo- and endocytosis. Hence, synapses rely on efficient proteostasis mechanisms to preserve their structure and function. To this end, the synaptic compartment has specific chaperones to support its functions. Without proper synaptic chaperone activity, local proteostasis imbalances lead to neurotransmission deficits, dismantling of synapses, and neurodegeneration. In this review, we address the roles of four synaptic chaperones in the maintenance of the nerve terminal, as well as their genetic links to neurodegenerative disease. Three of these are Hsp40 co-chaperones (DNAJs): Cysteine String Protein alpha (CSPα; DNAJC5), auxilin (DNAJC6), and Receptor-Mediated Endocytosis 8 (RME-8; DNAJC13). These co-chaperones contain a conserved J domain through which they form a complex with heat shock cognate 70 (Hsc70), enhancing the chaperone's ATPase activity. CSPα is a synaptic vesicle protein known to chaperone the t-SNARE SNAP-25 and the endocytic GTPase dynamin-1, thereby regulating synaptic vesicle exocytosis and endocytosis. Auxilin binds assembled clathrin cages, and through its interactions with Hsc70 leads to the uncoating of clathrin-coated vesicles, a process necessary for the regeneration of synaptic vesicles. RME-8 is a co-chaperone on endosomes and may have a role in clathrin-coated vesicle endocytosis on this organelle. These three co-chaperones maintain client function by preserving folding and assembly to prevent client aggregation, but they do not break down aggregates that have already formed. The fourth synaptic chaperone we will discuss is Heat shock protein 110 (Hsp110), which interacts with Hsc70, DNAJAs, and DNAJBs to constitute a disaggregase. Hsp110-related disaggregase activity is present at the synapse and is known to protect against aggregation of proteins such as α-synuclein. Congruent with their importance in the nervous system, mutations of these co-chaperones lead to familial neurodegenerative disease. CSPα mutations cause adult neuronal ceroid lipofuscinosis, while auxilin mutations result in early-onset Parkinson's disease, demonstrating their significance in preservation of the nervous system.
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Affiliation(s)
- Erica L Gorenberg
- Interdepartmental Neuroscience Program, Yale UniversityNew Haven, CT, United States
| | - Sreeganga S Chandra
- Department of Neurology, Yale UniversityNew Haven, CT, United States.,Department of Neuroscience, Yale UniversityNew Haven, CT, United States
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