1
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Brockmöller S, Worek F, Rothmiller S. Protein networking: nicotinic acetylcholine receptors and their protein-protein-associations. Mol Cell Biochem 2024:10.1007/s11010-024-05032-x. [PMID: 38771378 DOI: 10.1007/s11010-024-05032-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 05/04/2024] [Indexed: 05/22/2024]
Abstract
Nicotinic acetylcholine receptors (nAChR) are complex transmembrane proteins involved in neurotransmission in the nervous system and at the neuromuscular junction. nAChR disorders may lead to severe, potentially fatal pathophysiological states. To date, the receptor has been the focus of basic and applied research to provide novel therapeutic interventions. Since most studies have investigated only the nAChR itself, it is necessary to consider the receptor as part of its protein network to understand or elucidate-specific pathways. On its way through the secretory pathway, the receptor interacts with several chaperones and proteins. This review takes a closer look at these molecular interactions and focuses especially on endoplasmic reticulum biogenesis, secretory pathway sorting, Golgi maturation, plasma membrane presentation, retrograde internalization, and recycling. Additional knowledge regarding the nAChR protein network may lead to a more detailed comprehension of the fundamental pathomechanisms of diseases or may lead to the discovery of novel therapeutic drug targets.
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Affiliation(s)
- Sabrina Brockmöller
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Bavaria, Germany.
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Bavaria, Germany
| | - Simone Rothmiller
- Bundeswehr Institute of Pharmacology and Toxicology, Munich, Bavaria, Germany
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2
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Melnyk A, Lang S, Sicking M, Zimmermann R, Jung M. Co-chaperones of the Human Endoplasmic Reticulum: An Update. Subcell Biochem 2023; 101:247-291. [PMID: 36520310 DOI: 10.1007/978-3-031-14740-1_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
In mammalian cells, the rough endoplasmic reticulum (ER) plays central roles in the biogenesis of extracellular plus organellar proteins and in various signal transduction pathways. For these reasons, the ER comprises molecular chaperones, which are involved in import, folding, assembly, export, plus degradation of polypeptides, and signal transduction components, such as calcium channels, calcium pumps, and UPR transducers plus adenine nucleotide carriers/exchangers in the ER membrane. The calcium- and ATP-dependent ER lumenal Hsp70, termed immunoglobulin heavy-chain-binding protein or BiP, is the central player in all these activities and involves up to nine different Hsp40-type co-chaperones, i.e., ER membrane integrated as well as ER lumenal J-domain proteins, termed ERj or ERdj proteins, two nucleotide exchange factors or NEFs (Grp170 and Sil1), and NEF-antagonists, such as MANF. Here we summarize the current knowledge on the ER-resident BiP/ERj chaperone network and focus on the interaction of BiP with the polypeptide-conducting and calcium-permeable Sec61 channel of the ER membrane as an example for BiP action and how its functional cycle is linked to ER protein import and various calcium-dependent signal transduction pathways.
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Affiliation(s)
- Armin Melnyk
- Medical Biochemistry & Molecular Biology, Saarland University, Homburg, Germany
| | - Sven Lang
- Medical Biochemistry & Molecular Biology, Saarland University, Homburg, Germany
| | - Mark Sicking
- Medical Biochemistry & Molecular Biology, Saarland University, Homburg, Germany
| | - Richard Zimmermann
- Medical Biochemistry & Molecular Biology, Saarland University, Homburg, Germany.
| | - Martin Jung
- Medical Biochemistry & Molecular Biology, Saarland University, Homburg, Germany
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3
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Sicking M, Živná M, Bhadra P, Barešová V, Tirincsi A, Hadzibeganovic D, Hodaňová K, Vyleťal P, Sovová J, Jedličková I, Jung M, Bell T, Helms V, Bleyer AJ, Kmoch S, Cavalié A, Lang S. Phenylbutyrate rescues the transport defect of the Sec61α mutations V67G and T185A for renin. Life Sci Alliance 2022; 5:e202101150. [PMID: 35064074 PMCID: PMC8807872 DOI: 10.26508/lsa.202101150] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 01/06/2022] [Accepted: 01/06/2022] [Indexed: 11/24/2022] Open
Abstract
The human Sec61 complex is a widely distributed and abundant molecular machine. It resides in the membrane of the endoplasmic reticulum to channel two types of cargo: protein substrates and calcium ions. The SEC61A1 gene encodes for the pore-forming Sec61α subunit of the Sec61 complex. Despite their ubiquitous expression, the idiopathic SEC61A1 missense mutations p.V67G and p.T185A trigger a localized disease pattern diagnosed as autosomal dominant tubulointerstitial kidney disease (ADTKD-SEC61A1). Using cellular disease models for ADTKD-SEC61A1, we identified an impaired protein transport of the renal secretory protein renin and a reduced abundance of regulatory calcium transporters, including SERCA2. Treatment with the molecular chaperone phenylbutyrate reversed the defective protein transport of renin and the imbalanced calcium homeostasis. Signal peptide substitution experiments pointed at targeting sequences as the cause for the substrate-specific impairment of protein transport in the presence of the V67G or T185A mutations. Similarly, dominant mutations in the signal peptide of renin also cause ADTKD and point to impaired transport of this renal hormone as important pathogenic feature for ADTKD-SEC61A1 patients as well.
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Affiliation(s)
- Mark Sicking
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Martina Živná
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Pratiti Bhadra
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Veronika Barešová
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Andrea Tirincsi
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Drazena Hadzibeganovic
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Kateřina Hodaňová
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Petr Vyleťal
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Jana Sovová
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Ivana Jedličková
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Martin Jung
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Thomas Bell
- Department of Chemistry, University of Nevada, Reno, NV, USA
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Anthony J Bleyer
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
- Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Stanislav Kmoch
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Adolfo Cavalié
- Experimental and Clinical Pharmacology and Toxicology, Pre-clinical Center for Molecular Signaling (PZMS), Saarland University, Homburg, Germany
| | - Sven Lang
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
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4
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Trouvé P, Férec C, Génin E. The Interplay between the Unfolded Protein Response, Inflammation and Infection in Cystic Fibrosis. Cells 2021; 10:2980. [PMID: 34831204 PMCID: PMC8616505 DOI: 10.3390/cells10112980] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 10/25/2021] [Accepted: 10/29/2021] [Indexed: 12/15/2022] Open
Abstract
In cystic fibrosis (CF), p.Phe508del is the most frequent mutation in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene. The p.Phe508del-CFTR protein is retained in the ER and rapidly degraded. This retention likely triggers an atypical Unfolded Protein Response (UPR) involving ATF6, which reduces the expression of p.Phe508del-CFTR. There are still some debates on the role of the UPR in CF: could it be triggered by the accumulation of misfolded CFTR proteins in the endoplasmic reticulum as was proposed for the most common CFTR mutation p.Phe508del? Or, is it the consequence of inflammation and infection that occur in the disease? In this review, we summarize recent findings on UPR in CF and show how infection, inflammation and UPR act together in CF. We propose to rethink their respective role in CF and to consider them as a whole.
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Affiliation(s)
- Pascal Trouvé
- Inserm, Univ Brest, EFS, UMR 1078, GGB, F-29200 Brest, France; (C.F.); (E.G.)
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5
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Martínez J, Marmisolle I, Tarallo D, Quijano C. Mitochondrial Bioenergetics and Dynamics in Secretion Processes. Front Endocrinol (Lausanne) 2020; 11:319. [PMID: 32528413 PMCID: PMC7256191 DOI: 10.3389/fendo.2020.00319] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/27/2020] [Indexed: 12/12/2022] Open
Abstract
Secretion is an energy consuming process that plays a relevant role in cell communication and adaptation to the environment. Among others, endocrine cells producing hormones, immune cells producing cytokines or antibodies, neurons releasing neurotransmitters at synapsis, and more recently acknowledged, senescent cells synthesizing and secreting multiple cytokines, growth factors and proteases, require energy to successfully accomplish the different stages of the secretion process. Calcium ions (Ca2+) act as second messengers regulating secretion in many of these cases. In this setting, mitochondria appear as key players providing ATP by oxidative phosphorylation, buffering Ca2+ concentrations and acting as structural platforms. These tasks also require the concerted actions of the mitochondrial dynamics machinery. These proteins mediate mitochondrial fusion and fission, and are also required for transport and tethering of mitochondria to cellular organelles where the different steps of the secretion process take place. Herein we present a brief overview of mitochondrial energy metabolism, mitochondrial dynamics, and the different steps of the secretion processes, along with evidence of the interaction between these pathways. We also analyze the role of mitochondria in secretion by different cell types in physiological and pathological settings.
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Liu Q, Liang C, Zhou L. Structural and functional analysis of the Hsp70/Hsp40 chaperone system. Protein Sci 2019; 29:378-390. [PMID: 31509306 DOI: 10.1002/pro.3725] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 08/29/2019] [Accepted: 09/03/2019] [Indexed: 12/22/2022]
Abstract
As one of the most abundant and highly conserved molecular chaperones, the 70-kDa heat shock proteins (Hsp70s) play a key role in maintaining cellular protein homeostasis (proteostasis), one of the most fundamental tasks for every living organism. In this role, Hsp70s are inextricably linked to many human diseases, most notably cancers and neurodegenerative diseases, and are increasingly recognized as important drug targets for developing novel therapeutics for these diseases. Hsp40s are a class of essential and universal partners for Hsp70s in almost all aspects of proteostasis. Thus, Hsp70s and Hsp40s together constitute one of the most important chaperone systems across all kingdoms of life. In recent years, we have witnessed significant progress in understanding the molecular mechanism of this chaperone system through structural and functional analysis. This review will focus on this recent progress, mainly from a structural perspective.
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Affiliation(s)
- Qinglian Liu
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
| | - Ce Liang
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
| | - Lei Zhou
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, Virginia
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7
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Chiarelli N, Carini G, Zoppi N, Ritelli M, Colombi M. Molecular insights in the pathogenesis of classical Ehlers-Danlos syndrome from transcriptome-wide expression profiling of patients' skin fibroblasts. PLoS One 2019; 14:e0211647. [PMID: 30716086 PMCID: PMC6361458 DOI: 10.1371/journal.pone.0211647] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Accepted: 01/17/2019] [Indexed: 12/16/2022] Open
Abstract
Classical Ehlers-Danlos syndrome (cEDS) is a dominant inherited connective tissue disorder mainly caused by mutations in the COL5A1 and COL5A2 genes encoding type V collagen (COLLV), which is a fibrillar COLL widely distributed in a variety of connective tissues. cEDS patients suffer from skin hyperextensibility, abnormal wound healing/atrophic scars, and joint hypermobility. Most of the causative variants result in a non-functional COL5A1 allele and COLLV haploinsufficiency, whilst COL5A2 mutations affect its structural integrity. To shed light into disease mechanisms involved in cEDS, we performed gene expression profiling in skin fibroblasts from four patients harboring haploinsufficient and structural mutations in both disease genes. Transcriptome profiling revealed significant changes in the expression levels of different extracellular matrix (ECM)-related genes, such as SPP1, POSTN, EDIL3, IGFBP2, and C3, which encode both matricellular and soluble proteins that are mainly involved in cell proliferation and migration, and cutaneous wound healing. These gene expression changes are consistent with our previous protein findings on in vitro fibroblasts from other cEDS patients, which exhibited reduced migration and poor wound repair owing to COLLV disorganization, altered deposition of fibronectin into ECM, and an abnormal integrin pattern. Microarray analysis also indicated the decreased expression of DNAJB7, VIPAS39, CCPG1, ATG10, SVIP, which encode molecular chaperones facilitating protein folding, enzymes regulating post-Golgi COLLs processing, and proteins acting as cargo receptors required for endoplasmic reticulum (ER) proteostasis and implicated in the autophagy process. Patients’ cells also showed altered mRNA levels of many cell cycle regulating genes including CCNE2, KIF4A, MKI67, DTL, and DDIAS. Protein studies showed that aberrant COLLV expression causes the disassembly of itself and many structural ECM constituents including COLLI, COLLIII, fibronectin, and fibrillins. Our findings provide the first molecular evidence of significant gene expression changes in cEDS skin fibroblasts highlighting that defective ECM remodeling, ER homeostasis and autophagy might play a role in the pathogenesis of this connective tissue disorder.
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Affiliation(s)
- Nicola Chiarelli
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Giulia Carini
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Nicoletta Zoppi
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Marco Ritelli
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Marina Colombi
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
- * E-mail:
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8
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Kampinga HH, Andreasson C, Barducci A, Cheetham ME, Cyr D, Emanuelsson C, Genevaux P, Gestwicki JE, Goloubinoff P, Huerta-Cepas J, Kirstein J, Liberek K, Mayer MP, Nagata K, Nillegoda NB, Pulido P, Ramos C, De Los Rios P, Rospert S, Rosenzweig R, Sahi C, Taipale M, Tomiczek B, Ushioda R, Young JC, Zimmermann R, Zylicz A, Zylicz M, Craig EA, Marszalek J. Function, evolution, and structure of J-domain proteins. Cell Stress Chaperones 2019; 24:7-15. [PMID: 30478692 PMCID: PMC6363617 DOI: 10.1007/s12192-018-0948-4] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2018] [Indexed: 01/06/2023] Open
Abstract
Hsp70 chaperone systems are very versatile machines present in nearly all living organisms and in nearly all intracellular compartments. They function in many fundamental processes through their facilitation of protein (re)folding, trafficking, remodeling, disaggregation, and degradation. Hsp70 machines are regulated by co-chaperones. J-domain containing proteins (JDPs) are the largest family of Hsp70 co-chaperones and play a determining role functionally specifying and directing Hsp70 functions. Many features of JDPs are not understood; however, a number of JDP experts gathered at a recent CSSI-sponsored workshop in Gdansk (Poland) to discuss various aspects of J-domain protein function, evolution, and structure. In this report, we present the main findings and the consensus reached to help direct future developments in the field of Hsp70 research.
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Affiliation(s)
- Harm H Kampinga
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Claes Andreasson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91, Stockholm, Sweden
| | - Alessandro Barducci
- Inserm, U1054, CNRS, UMR 5048, Centre de Biochimie Structurale, Universite de Montpellier, Montpellier, France
| | | | - Douglas Cyr
- University of North Carolina, Chapel Hill, NC, USA
| | - Cecilia Emanuelsson
- Center for Molecular Protein Sciences, CMPS, Dept. Biochemistry and Structural Biology, Lund University, Lund, Sweden
| | - Pierre Genevaux
- Laboratoire de Microbiologie et de Génétique Moléculaires, Centre de Biologie Intégrative (CBI), CNRS-Université de Toulouse, 118 route de Narbonne, 31062, Toulouse Cedex 9, France
| | - Jason E Gestwicki
- Institute for Neurodegenerative Diseases, University of California, San Francisco, CA, USA
| | - Pierre Goloubinoff
- Department of Plant Molecular Biology, University of Lausanne, Lausanne, Switzerland
| | | | - Janine Kirstein
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP), Berlin, Germany
| | - Krzysztof Liberek
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307, Gdansk, Poland
| | - Matthias P Mayer
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany
| | - Kazuhiro Nagata
- Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, 603-8555, Japan
| | - Nadinath B Nillegoda
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany
- Australian Regenerative Medicine Institute (ARMI), Monash University, 15 Innovative Walk, Wellington Road, Clayton, VIC, 3800, Australia
| | - Pablo Pulido
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University, Planegg-Martinsried, 82152, Munich, Germany
| | - Carlos Ramos
- Institute of Chemistry, University of Campinas UNICAMP, Campinas, SP, Brazil
| | - Paolo De Los Rios
- EPFL SB IPHYS LBS BSP 723 (Cubotron UNIL), Rte de la Sorge, CH-1015, Lausanne, Switzerland
| | - Sabine Rospert
- Institut fur Biochemie und Molekularbiologie, Universitat Freiburg, Freiburg, Germany
| | | | - Chandan Sahi
- Indian Institute of Science Education and Research Bhopal, Bhauri Bhopal, Madhya Pradesh, 462 066, India
| | - Mikko Taipale
- Donnelly Centre for Cellular and Biomolecular Research, Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Bratłomiej Tomiczek
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307, Gdansk, Poland
| | - Ryo Ushioda
- Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, 603-8555, Japan
| | - Jason C Young
- Department of Biochemistry, McGill University, Montreal, Canada
| | - Richard Zimmermann
- Medical Biochemistry and Molecular Biology, Saarland University, 66421, Homburg, Germany
| | - Alicja Zylicz
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Maciej Zylicz
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Elizabeth A Craig
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Jaroslaw Marszalek
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307, Gdansk, Poland
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9
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Lang S, Nguyen D, Pfeffer S, Förster F, Helms V, Zimmermann R. Functions and Mechanisms of the Human Ribosome-Translocon Complex. Subcell Biochem 2019; 93:83-141. [PMID: 31939150 DOI: 10.1007/978-3-030-28151-9_4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The membrane of the endoplasmic reticulum (ER) in human cells harbors the protein translocon, which facilitates membrane insertion and translocation of almost every newly synthesized polypeptide targeted to organelles of the secretory pathway. The translocon comprises the polypeptide-conducting Sec61 channel and several additional proteins, which are associated with the heterotrimeric Sec61 complex. This ensemble of proteins facilitates ER targeting of precursor polypeptides, Sec61 channel opening and closing, and modification of precursor polypeptides in transit through the Sec61 complex. Recently, cryoelectron tomography of translocons in native ER membranes has given unprecedented insights into the architecture and dynamics of the native, ribosome-associated translocon and the Sec61 channel. These structural data are discussed in light of different Sec61 channel activities including ribosome receptor function, membrane insertion or translocation of newly synthesized polypeptides as well as the possible roles of the Sec61 channel as a passive ER calcium leak channel and regulator of ATP/ADP exchange between cytosol and ER.
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Affiliation(s)
- Sven Lang
- Competence Center for Molecular Medicine, Saarland University Medical School, Building 44, 66421, Homburg, Germany.
| | - Duy Nguyen
- Center for Bioinformatics, Saarland University, 66041, Saarbrücken, Germany
| | - Stefan Pfeffer
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152, Martinsried, Germany
- ZMBH, 69120, Heidelberg, Germany
| | - Friedrich Förster
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152, Martinsried, Germany
- Center for Biomolecular Research, Utrecht University, 3584 CH, Utrecht, The Netherlands
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, 66041, Saarbrücken, Germany
| | - Richard Zimmermann
- Competence Center for Molecular Medicine, Saarland University Medical School, Building 44, 66421, Homburg, Germany
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10
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Xiong J, Ding N, Gao T, Wang Y, Guo W, Zhang H, Ma X, Li F, Sun J, Yang X, Wu K, Zhang H, Jiang Y. Hypermethylation of endoplasmic reticulum disulfide oxidase 1α leads to trophoblast cell apoptosis through endoplasmic reticulum stress in preeclampsia. J Cell Biochem 2018; 119:8588-8599. [PMID: 30058081 DOI: 10.1002/jcb.27101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 04/27/2018] [Indexed: 12/16/2022]
Abstract
Abnormal trophoblast cell apoptosis is implicated in the pathogenesis of pregnancy-related disorders including preeclampsia (PE), and endoplasmic reticulum (ER) stress has been considered as a novel pathway in the regulation of cell apoptosis. In this study, we observed that both apoptosis and ER stress are triggered in trophoblast cells under hypoxia as well as in the placenta of PE rats. Quantitative polymerase chain reaction and Western blot analysis showed that the expression of endoplasmic reticulum disulfide oxidase 1α (ERO1α) is suppressed in trophoblast cells under hypoxia due to the hypermethylation of the ERO1α promoter region, and the inhibition of ERO1α expression plays an important role in ER stress and trophoblast cell apoptosis. Furthermore, we found that DNA methyltransferase 1 (DNMT1) is a key methyltransferase for DNA methylation in the regulation of ERO1α expression, and the binding level of DNMT1 to the ERO1α promoter is markedly elevated under hypoxia although DNMT1 expression is inhibited by hypoxia, suggesting that the binding level of DNMT1 to the ERO1α promoter region rather than the DNMT1 expression level contributes to the hypermethylation of ERO1α. Taken together, these results demonstrate that the hypermethylation of ERO1α mediated by increased binding of DNMT1 to the ERO1α promoter leads to trophoblast cell apoptosis through ER stress in the placenta of PE rats, which shed insight into the etiology of PE and might present a validated therapeutic target for the treatment of PE.
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Affiliation(s)
- Jiantuan Xiong
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Ning Ding
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China.,Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Tingting Gao
- Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China.,Department of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Yanhua Wang
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China.,Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Wei Guo
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China.,Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Hui Zhang
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China.,Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Xiaoli Ma
- Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China.,Department of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Fan Li
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China.,Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Jianmin Sun
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China.,Division of Translational Cancer Research, Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Xiaoling Yang
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China.,Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Kai Wu
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Huiping Zhang
- Department of Prenatal Diagnosis Center, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China
| | - Yideng Jiang
- School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, Ningxia, China.,Ningxia Key Laboratory of Vascular Injury and Repair Research, Ningxia Medical University, Yinchuan, Ningxia, China
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11
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Chiarelli N, Carini G, Zoppi N, Ritelli M, Colombi M. Transcriptome analysis of skin fibroblasts with dominant negative COL3A1 mutations provides molecular insights into the etiopathology of vascular Ehlers-Danlos syndrome. PLoS One 2018; 13:e0191220. [PMID: 29346445 PMCID: PMC5773204 DOI: 10.1371/journal.pone.0191220] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 12/29/2017] [Indexed: 01/20/2023] Open
Abstract
Vascular Ehlers-Danlos syndrome (vEDS) is a dominantly inherited connective tissue disorder caused by mutations in the COL3A1 gene that encodes type III collagen (COLLIII), which is the major expressed collagen in blood vessels and hollow organs. The majority of disease-causing variants in COL3A1 are glycine substitutions and in-frame splice mutations in the triple helix domain that through a dominant negative effect are associated with the severe clinical spectrum potentially lethal of vEDS, characterized by fragility of soft connective tissues with arterial and organ ruptures. To shed lights into molecular mechanisms underlying vEDS, we performed gene expression profiling in cultured skin fibroblasts from three patients with different structural COL3A1 mutations. Transcriptome analysis revealed significant changes in the expression levels of several genes involved in maintenance of cell redox and endoplasmic reticulum (ER) homeostasis, COLLs folding and extracellular matrix (ECM) organization, formation of the proteasome complex, and cell cycle regulation. Protein analyses showed that aberrant COLLIII expression is associated with the disassembly of many structural ECM constituents, such as fibrillins, EMILINs, and elastin, as well as with the reduction of the proteoglycans perlecan, decorin, and versican, all playing an important role in the vascular system. Furthermore, the altered distribution of the ER marker protein disulfide isomerase PDI and the strong reduction of the COLLs-modifying enzyme FKBP22 are consistent with the disturbance of ER-related homeostasis and COLLs biosynthesis and post-translational modifications, indicated by microarray analysis. Our findings add new insights into the pathophysiology of this severe vascular disorder, since they provide a picture of the gene expression changes in vEDS skin fibroblasts and highlight that dominant negative mutations in COL3A1 also affect post-translational modifications and deposition into the ECM of several structural proteins crucial to the integrity of soft connective tissues.
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Affiliation(s)
- Nicola Chiarelli
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Giulia Carini
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Nicoletta Zoppi
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Marco Ritelli
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
| | - Marina Colombi
- Department of Molecular and Translational Medicine, Division of Biology and Genetics, University of Brescia, Brescia, Italy
- * E-mail:
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12
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Bakunts A, Orsi A, Vitale M, Cattaneo A, Lari F, Tadè L, Sitia R, Raimondi A, Bachi A, van Anken E. Ratiometric sensing of BiP-client versus BiP levels by the unfolded protein response determines its signaling amplitude. eLife 2017; 6:27518. [PMID: 29251598 PMCID: PMC5792092 DOI: 10.7554/elife.27518] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 12/15/2017] [Indexed: 01/03/2023] Open
Abstract
Insufficient folding capacity of the endoplasmic reticulum (ER) activates the unfolded protein response (UPR) to restore homeostasis. Yet, how the UPR achieves ER homeostatic readjustment is poorly investigated, as in most studies the ER stress that is elicited cannot be overcome. Here we show that a proteostatic insult, provoked by persistent expression of the secretory heavy chain of immunoglobulin M (µs), is well-tolerated in HeLa cells. Upon µs expression, its levels temporarily eclipse those of the ER chaperone BiP, leading to acute, full-geared UPR activation. Once BiP is in excess again, the UPR transitions to chronic, submaximal activation, indicating that the UPR senses ER stress in a ratiometric fashion. In this process, the ER expands about three-fold and becomes dominated by BiP. As the UPR is essential for successful ER homeostatic readjustment in the HeLa-µs model, it provides an ideal system for dissecting the intricacies of how the UPR evaluates and alleviates ER stress.
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Affiliation(s)
- Anush Bakunts
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Andrea Orsi
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
| | - Milena Vitale
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
| | | | - Federica Lari
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Laura Tadè
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Roberto Sitia
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
| | - Andrea Raimondi
- Experimental Imaging Center, San Raffaele Scientific Institute, Milan, Italy
| | - Angela Bachi
- IFOM, FIRC Institute of Molecular Oncology, Milan, Italy
| | - Eelco van Anken
- Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy.,Università Vita-Salute San Raffaele, Milan, Italy
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13
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Lang S, Pfeffer S, Lee PH, Cavalié A, Helms V, Förster F, Zimmermann R. An Update on Sec61 Channel Functions, Mechanisms, and Related Diseases. Front Physiol 2017; 8:887. [PMID: 29163222 PMCID: PMC5672155 DOI: 10.3389/fphys.2017.00887] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/19/2017] [Indexed: 12/18/2022] Open
Abstract
The membrane of the endoplasmic reticulum (ER) of nucleated human cells harbors the protein translocon, which facilitates membrane integration or translocation of almost every newly synthesized polypeptide targeted to organelles of the endo- and exocytotic pathway. The translocon comprises the polypeptide-conducting Sec61 channel and several additional proteins and complexes that are permanently or transiently associated with the heterotrimeric Sec61 complex. This ensemble of proteins facilitates ER targeting of precursor polypeptides, modification of precursor polypeptides in transit through the Sec61 complex, and Sec61 channel gating, i.e., dynamic regulation of the pore forming subunit to mediate precursor transport and calcium efflux. Recently, cryoelectron tomography of translocons in native ER membrane vesicles, derived from human cell lines or patient fibroblasts, and even intact cells has given unprecedented insights into the architecture and dynamics of the native translocon and the Sec61 channel. These structural data are discussed in light of different Sec61 channel activities including ribosome receptor function, membrane insertion, and translocation of newly synthesized polypeptides as well as the putative physiological roles of the Sec61 channel as a passive ER calcium leak channel. Furthermore, the structural insights into the Sec61 channel are incorporated into an overview and update on Sec61 channel-related diseases—the Sec61 channelopathies—and novel therapeutic concepts for their treatment.
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Affiliation(s)
- Sven Lang
- Competence Center for Molecular Medicine, Saarland University Medical School, Homburg, Germany
| | - Stefan Pfeffer
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Po-Hsien Lee
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Adolfo Cavalié
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, Homburg, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Friedrich Förster
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Richard Zimmermann
- Competence Center for Molecular Medicine, Saarland University Medical School, Homburg, Germany
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14
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Chen KC, Qu S, Chowdhury S, Noxon IC, Schonhoft JD, Plate L, Powers ET, Kelly JW, Lander GC, Wiseman RL. The endoplasmic reticulum HSP40 co-chaperone ERdj3/DNAJB11 assembles and functions as a tetramer. EMBO J 2017; 36:2296-2309. [PMID: 28655754 DOI: 10.15252/embj.201695616] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 05/15/2017] [Accepted: 05/22/2017] [Indexed: 11/09/2022] Open
Abstract
ERdj3/DNAJB11 is an endoplasmic reticulum (ER)-targeted HSP40 co-chaperone that performs multifaceted functions involved in coordinating ER and extracellular proteostasis. Here, we show that ERdj3 assembles into a native tetramer that is distinct from the dimeric structure observed for other HSP40 co-chaperones. An electron microscopy structural model of full-length ERdj3 shows that these tetramers are arranged as a dimer of dimers formed by distinct inter-subunit interactions involving ERdj3 domain II and domain III Targeted deletion of residues 175-190 within domain II renders ERdj3 a stable dimer that is folded and efficiently secreted from mammalian cells. This dimeric ERdj3 shows impaired substrate binding both in the ER and extracellular environments and reduced interactions with the ER HSP70 chaperone BiP. Furthermore, we show that overexpression of dimeric ERdj3 exacerbates ER stress-dependent reductions in the secretion of a destabilized, aggregation-prone protein and increases its accumulation as soluble oligomers in extracellular environments. These results reveal ERdj3 tetramerization as an important structural framework for ERdj3 functions involved in coordinating ER and extracellular proteostasis in the presence and absence of ER stress.
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Affiliation(s)
- Kai-Chun Chen
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Song Qu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Saikat Chowdhury
- Department of Integrative, Structural, and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Isabelle C Noxon
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Joseph D Schonhoft
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Lars Plate
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA.,Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Evan T Powers
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Jeffery W Kelly
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA.,Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Gabriel C Lander
- Department of Integrative, Structural, and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - R Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
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15
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Gutiérrez T, Simmen T. Endoplasmic reticulum chaperones tweak the mitochondrial calcium rheostat to control metabolism and cell death. Cell Calcium 2017; 70:64-75. [PMID: 28619231 DOI: 10.1016/j.ceca.2017.05.015] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 05/24/2017] [Accepted: 05/24/2017] [Indexed: 12/16/2022]
Abstract
The folding of secretory proteins is a well-understood mechanism, based on decades of research on endoplasmic reticulum (ER) chaperones. These chaperones interact with newly imported polypeptides close to the ER translocon. Classic examples for these proteins include the immunoglobulin binding protein (BiP/GRP78), and the lectins calnexin and calreticulin. Although not considered chaperones per se, the ER oxidoreductases of the protein disulfide isomerase (PDI) family complete the folding job by catalyzing the formation of disulfide bonds through cysteine oxidation. Research from the past decade has demonstrated that ER chaperones are multifunctional proteins. The regulation of ER-mitochondria Ca2+ crosstalk is one of their additional functions, as shown for calnexin, BiP/GRP78 or the oxidoreductases Ero1α and TMX1. This function depends on interactions of this group of proteins with the ER Ca2+ handling machinery. This novel function makes perfect sense for two reasons: i. It allows ER chaperones to control mitochondrial apoptosis instantly without a lengthy bypass involving the upregulation of pro-apoptotic transcription factors via the unfolded protein response (UPR); and ii. It allows the ER protein folding machinery to fine-tune ATP import via controlling the speed of mitochondrial oxidative phosphorylation. Therefore, the role of ER chaperones in regulating ER-mitochondria Ca2+ flux identifies the progression of secretory protein folding as a central regulator of cell survival and death, at least in cell types that secrete large amount of proteins. In other cell types, ER protein folding might serve as a sentinel mechanism that monitors cellular well-being to control cell metabolism and apoptosis. The selenoprotein SEPN1 is a classic example for such a role. Through the control of ER-mitochondria Ca2+-flux, ER chaperones and folding assistants guide cellular apoptosis and mitochondrial metabolism.
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Affiliation(s)
- Tomas Gutiérrez
- Faculty of Medicine and Dentistry, Department of Cell Biology, University of Alberta, Edmonton, T6G2H7, Canada
| | - Thomas Simmen
- Faculty of Medicine and Dentistry, Department of Cell Biology, University of Alberta, Edmonton, T6G2H7, Canada,.
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16
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Lackie RE, Maciejewski A, Ostapchenko VG, Marques-Lopes J, Choy WY, Duennwald ML, Prado VF, Prado MAM. The Hsp70/Hsp90 Chaperone Machinery in Neurodegenerative Diseases. Front Neurosci 2017; 11:254. [PMID: 28559789 PMCID: PMC5433227 DOI: 10.3389/fnins.2017.00254] [Citation(s) in RCA: 232] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/20/2017] [Indexed: 12/12/2022] Open
Abstract
The accumulation of misfolded proteins in the human brain is one of the critical features of many neurodegenerative diseases, including Alzheimer's disease (AD). Assembles of beta-amyloid (Aβ) peptide—either soluble (oligomers) or insoluble (plaques) and of tau protein, which form neurofibrillary tangles, are the major hallmarks of AD. Chaperones and co-chaperones regulate protein folding and client maturation, but they also target misfolded or aggregated proteins for refolding or for degradation, mostly by the proteasome. They form an important line of defense against misfolded proteins and are part of the cellular quality control system. The heat shock protein (Hsp) family, particularly Hsp70 and Hsp90, plays a major part in this process and it is well-known to regulate protein misfolding in a variety of diseases, including tau levels and toxicity in AD. However, the role of Hsp90 in regulating protein misfolding is not yet fully understood. For example, knockdown of Hsp90 and its co-chaperones in a Caenorhabditis elegans model of Aβ misfolding leads to increased toxicity. On the other hand, the use of Hsp90 inhibitors in AD mouse models reduces Aβ toxicity, and normalizes synaptic function. Stress-inducible phosphoprotein 1 (STI1), an intracellular co-chaperone, mediates the transfer of clients from Hsp70 to Hsp90. Importantly, STI1 has been shown to regulate aggregation of amyloid-like proteins in yeast. In addition to its intracellular function, STI1 can be secreted by diverse cell types, including astrocytes and microglia and function as a neurotrophic ligand by triggering signaling via the cellular prion protein (PrPC). Extracellular STI1 can prevent Aβ toxic signaling by (i) interfering with Aβ binding to PrPC and (ii) triggering pro-survival signaling cascades. Interestingly, decreased levels of STI1 in C. elegans can also increase toxicity in an amyloid model. In this review, we will discuss the role of intracellular and extracellular STI1 and the Hsp70/Hsp90 chaperone network in mechanisms underlying protein misfolding in neurodegenerative diseases, with particular focus on AD.
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Affiliation(s)
- Rachel E Lackie
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada.,Program in Neuroscience, University of Western OntarioLondon, ON, Canada
| | - Andrzej Maciejewski
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada.,Department of Biochemistry, University of Western OntarioLondon, ON, Canada
| | - Valeriy G Ostapchenko
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada
| | - Jose Marques-Lopes
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada
| | - Wing-Yiu Choy
- Department of Biochemistry, University of Western OntarioLondon, ON, Canada
| | - Martin L Duennwald
- Department of Pathology and Laboratory Medicine, University of Western OntarioLondon, ON, Canada
| | - Vania F Prado
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada.,Program in Neuroscience, University of Western OntarioLondon, ON, Canada.,Department of Physiology and Pharmacology, University of Western OntarioLondon, ON, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western OntarioLondon, ON, Canada
| | - Marco A M Prado
- Molecular Medicine, Robarts Research Institute, University of Western OntarioLondon, ON, Canada.,Program in Neuroscience, University of Western OntarioLondon, ON, Canada.,Department of Physiology and Pharmacology, University of Western OntarioLondon, ON, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western OntarioLondon, ON, Canada
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17
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Modulation of Molecular Chaperones in Huntington’s Disease and Other Polyglutamine Disorders. Mol Neurobiol 2016; 54:5829-5854. [DOI: 10.1007/s12035-016-0120-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 09/12/2016] [Indexed: 12/20/2022]
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18
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A Conserved Cysteine within the ATPase Domain of the Endoplasmic Reticulum Chaperone BiP is Necessary for a Complete Complement of BiP Activities. J Mol Biol 2016; 428:4168-4184. [PMID: 27543005 DOI: 10.1016/j.jmb.2016.08.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 08/04/2016] [Accepted: 08/06/2016] [Indexed: 01/25/2023]
Abstract
Among the amino acids, cysteine stands apart based on its highly reactive sulfur group. In general, cysteine is underrepresented in proteins. Yet, when present, the features of cysteine often afford unique function. We have shown previously that a cysteine within the ATPase domain of yeast BiP (Kar2) serves as a sensor of the endoplasmic reticulum (ER) redox environment [1, 2]. Under conditions of increased oxidant (oxidative stress), this cysteine becomes oxidized, changing Kar2 from an ATP-dependent foldase to an ATP-independent holdase. We were struck by the high degree of conservation for this cysteine between BiP orthologs, and we sought to determine how cysteine substitution impacts Kar2 function. We observed that no single amino acid replacement is capable of recreating the range of functions that can be achieved by wild-type Kar2 with its cysteine in either unmodified or oxidized states. However, we were able to generate mutants that could selectively replicate the distinct activities exhibited by either unmodified or oxidized Kar2. We found that the ATPase activity displayed by unmodified Kar2 is fully maintained when Cys63 is replaced with Ala or Val. Conversely, we demonstrate that several amino acid substitutions (including His, Phe, Pro, Trp, and Tyr) support an enhanced viability during oxidative stress associated with oxidized Kar2, although these alleles are compromised as an ATPase. We reveal that the range of activity demonstrated by wild-type Kar2 can be replicated by co-expression of Kar2 mutants that mimic either the unmodified or oxidized Kar2 state, allowing for growth during standard and oxidative stress conditions.
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19
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Ellgaard L, McCaul N, Chatsisvili A, Braakman I. Co- and Post-Translational Protein Folding in the ER. Traffic 2016; 17:615-38. [PMID: 26947578 DOI: 10.1111/tra.12392] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 02/26/2016] [Accepted: 03/03/2016] [Indexed: 12/19/2022]
Abstract
The biophysical rules that govern folding of small, single-domain proteins in dilute solutions are now quite well understood. The mechanisms underlying co-translational folding of multidomain and membrane-spanning proteins in complex cellular environments are often less clear. The endoplasmic reticulum (ER) produces a plethora of membrane and secretory proteins, which must fold and assemble correctly before ER exit - if these processes fail, misfolded species accumulate in the ER or are degraded. The ER differs from other cellular organelles in terms of the physicochemical environment and the variety of ER-specific protein modifications. Here, we review chaperone-assisted co- and post-translational folding and assembly in the ER and underline the influence of protein modifications on these processes. We emphasize how method development has helped advance the field by allowing researchers to monitor the progression of folding as it occurs inside living cells, while at the same time probing the intricate relationship between protein modifications during folding.
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Affiliation(s)
- Lars Ellgaard
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Nicholas McCaul
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Anna Chatsisvili
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Ineke Braakman
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Utrecht, The Netherlands
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20
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Zimmermann R. Components and Mechanisms of Import, Modification, Folding, and Assembly of Immunoglobulins in the Endoplasmic Reticulum. J Clin Immunol 2016; 36 Suppl 1:5-11. [PMID: 26923573 DOI: 10.1007/s10875-016-0250-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 02/19/2016] [Indexed: 11/27/2022]
Abstract
In mammalian cells, the endoplasmic reticulum (ER) plays a central role in biogenesis of secretory- and plasma membrane proteins as well as in cellular calcium (Ca(2+)) homeostasis. The protein biogenesis function involves an aqueous polypeptide conducting channel in the ER membrane, which is formed by the heterotrimeric Sec61 complex; the store- and receptor-controlled Ca(2+)- release function requires a steep ER to cytosol gradient, with more than 500 μM free Ca(2+) in the ER and 50 nM Ca(2+) in the cytosol. Recent work demonstrated that the Sec61 complex can transiently allow passive ER Ca(2+) efflux. Therefore, gating of the Sec61 channel has to be tightly regulated by substrates as well as allosteric effectors. The ER lumenal Hsp70-type molecular chaperone, immunoglobulin heavy-chain binding protein (BiP), together with its membrane resident co-chaperone Sec63 facilitates channel opening in a precursor specific manner. In addition, BiP, together with its lumenal co-chaperones, ERj3 and ERj6, as well as cytosolic Ca(2+)-calmodulin (CaM) in collaboration with the membrane resident Sec62 protein represent allosteric effectors for channel closure. In the course of the last couple of years several human diseases were linked to the Sec61 complex and its effectors and were termed Sec61-channelopathies.
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Affiliation(s)
- Richard Zimmermann
- Competence Center for Molecular Medicine, Saarland University Medical School, Building 44, D-66421, Homburg, Germany.
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21
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Schorr S, Klein MC, Gamayun I, Melnyk A, Jung M, Schäuble N, Wang Q, Hemmis B, Bochen F, Greiner M, Lampel P, Urban SK, Hassdenteufel S, Dudek J, Chen XZ, Wagner R, Cavalié A, Zimmermann R. Co-chaperone Specificity in Gating of the Polypeptide Conducting Channel in the Membrane of the Human Endoplasmic Reticulum. J Biol Chem 2015; 290:18621-35. [PMID: 26085089 DOI: 10.1074/jbc.m115.636639] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Indexed: 11/06/2022] Open
Abstract
In mammalian cells, signal peptide-dependent protein transport into the endoplasmic reticulum (ER) is mediated by a dynamic polypeptide-conducting channel, the heterotrimeric Sec61 complex. Previous work has characterized the Sec61 complex as a potential ER Ca(2+) leak channel in HeLa cells and identified ER lumenal molecular chaperone immunoglobulin heavy-chain-binding protein (BiP) as limiting Ca(2+) leakage via the open Sec61 channel by facilitating channel closing. This BiP activity involves binding of BiP to the ER lumenal loop 7 of Sec61α in the vicinity of tyrosine 344. Of note, the Y344H mutation destroys the BiP binding site and causes pancreatic β-cell apoptosis and diabetes in mice. Here, we systematically depleted HeLa cells of the BiP co-chaperones by siRNA-mediated gene silencing and used live cell Ca(2+) imaging to monitor the effects on ER Ca(2+) leakage. Depletion of either one of the ER lumenal BiP co-chaperones, ERj3 and ERj6, but not the ER membrane-resident co-chaperones (such as Sec63 protein, which assists BiP in Sec61 channel opening) led to increased Ca(2+) leakage via Sec6 complex, thereby phenocopying the effect of BiP depletion. Thus, BiP facilitates Sec61 channel closure (i.e. limits ER Ca(2+) leakage) via the Sec61 channel with the help of ERj3 and ERj6. Interestingly, deletion of ERj6 causes pancreatic β-cell failure and diabetes in mice and humans. We suggest that co-chaperone-controlled gating of the Sec61 channel by BiP is particularly important for cells, which are highly active in protein secretion, and that breakdown of this regulatory mechanism can cause apoptosis and disease.
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Affiliation(s)
- Stefan Schorr
- From the Departments of Medical Biochemistry and Molecular Biology and
| | | | - Igor Gamayun
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg, Germany
| | - Armin Melnyk
- From the Departments of Medical Biochemistry and Molecular Biology and
| | - Martin Jung
- From the Departments of Medical Biochemistry and Molecular Biology and
| | - Nico Schäuble
- From the Departments of Medical Biochemistry and Molecular Biology and
| | - Qian Wang
- the Department of Physiology, University of Alberta, Edmonton T6G 2H7, Canada, and
| | - Birgit Hemmis
- the Division of Biophysics, Universität Osnabrück, FB Biologie/Chemie, 49076 Osnabrück, Germany
| | - Florian Bochen
- From the Departments of Medical Biochemistry and Molecular Biology and
| | - Markus Greiner
- From the Departments of Medical Biochemistry and Molecular Biology and
| | - Pavel Lampel
- From the Departments of Medical Biochemistry and Molecular Biology and
| | | | | | - Johanna Dudek
- From the Departments of Medical Biochemistry and Molecular Biology and
| | - Xing-Zhen Chen
- the Department of Physiology, University of Alberta, Edmonton T6G 2H7, Canada, and
| | - Richard Wagner
- the Division of Biophysics, Universität Osnabrück, FB Biologie/Chemie, 49076 Osnabrück, Germany
| | - Adolfo Cavalié
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg, Germany
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22
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Finka A, Sharma SK, Goloubinoff P. Multi-layered molecular mechanisms of polypeptide holding, unfolding and disaggregation by HSP70/HSP110 chaperones. Front Mol Biosci 2015; 2:29. [PMID: 26097841 PMCID: PMC4456865 DOI: 10.3389/fmolb.2015.00029] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 05/19/2015] [Indexed: 11/24/2022] Open
Abstract
Members of the HSP70/HSP110 family (HSP70s) form a central hub of the chaperone network controlling all aspects of proteostasis in bacteria and the ATP-containing compartments of eukaryotic cells. The heat-inducible form HSP70 (HSPA1A) and its major cognates, cytosolic HSC70 (HSPA8), endoplasmic reticulum BIP (HSPA5), mitochondrial mHSP70 (HSPA9) and related HSP110s (HSPHs), contribute about 3% of the total protein mass of human cells. The HSP70s carry out a plethora of housekeeping cellular functions, such as assisting proper de novo folding, assembly and disassembly of protein complexes, pulling polypeptides out of the ribosome and across membrane pores, activating and inactivating signaling proteins and controlling their degradation. The HSP70s can induce structural changes in alternatively folded protein conformers, such as clathrin cages, hormone receptors and transcription factors, thereby regulating vesicular trafficking, hormone signaling and cell differentiation in development and cancer. To carry so diverse cellular housekeeping and stress-related functions, the HSP70s act as ATP-fuelled unfolding nanomachines capable of switching polypeptides between different folded states. During stress, the HSP70s can bind (hold) and prevent the aggregation of misfolding proteins and thereafter act alone or in collaboration with other unfolding chaperones to solubilize protein aggregates. Here, we discuss the common ATP-dependent mechanisms of holding, unfolding-by-clamping and unfolding-by-entropic pulling, by which the HSP70s can apparently convert various alternatively folded and misfolded polypeptides into differently active conformers. Understanding how HSP70s can prevent the formation of cytotoxic protein aggregates, pull, unfold, and solubilize them into harmless species is central to the design of therapies against protein conformational diseases.
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Affiliation(s)
- Andrija Finka
- Department of Plant Molecular Biology, Faculty of Biology and Medicine, University of Lausanne Lausanne, Switzerland ; Laboratoire de Biophysique Statistique, School of Basic Sciences, École Polytechnique Fédérale de Lausanne Lausanne, Switzerland
| | | | - Pierre Goloubinoff
- Department of Plant Molecular Biology, Faculty of Biology and Medicine, University of Lausanne Lausanne, Switzerland
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Behnke J, Feige MJ, Hendershot LM. BiP and its nucleotide exchange factors Grp170 and Sil1: mechanisms of action and biological functions. J Mol Biol 2015; 427:1589-608. [PMID: 25698114 DOI: 10.1016/j.jmb.2015.02.011] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/10/2015] [Accepted: 02/10/2015] [Indexed: 12/26/2022]
Abstract
BiP (immunoglobulin heavy-chain binding protein) is the endoplasmic reticulum (ER) orthologue of the Hsp70 family of molecular chaperones and is intricately involved in most functions of this organelle through its interactions with a variety of substrates and regulatory proteins. Like all Hsp70 family members, the ability of BiP to bind and release unfolded proteins is tightly regulated by a cycle of ATP binding, hydrolysis, and nucleotide exchange. As a characteristic of the Hsp70 family, multiple DnaJ-like co-factors can target substrates to BiP and stimulate its ATPase activity to stabilize the binding of BiP to substrates. However, only in the past decade have nucleotide exchange factors for BiP been identified, which has shed light not only on the mechanism of BiP-assisted folding in the ER but also on Hsp70 family members that reside throughout the cell. We will review the current understanding of the ATPase cycle of BiP in the unique environment of the ER and how it is regulated by the nucleotide exchange factors, Grp170 (glucose-regulated protein of 170kDa) and Sil1, both of which perform unanticipated roles in various biological functions and disease states.
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Affiliation(s)
- Julia Behnke
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Matthias J Feige
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Linda M Hendershot
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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