1
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Soldà T, Galli C, Guerra C, Hoefner C, Molinari M. TMX5/TXNDC15, a natural trapping mutant of the PDI family is a client of the proteostatic factor ERp44. Life Sci Alliance 2024; 7:e202403047. [PMID: 39348940 PMCID: PMC11443168 DOI: 10.26508/lsa.202403047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2024] [Revised: 09/23/2024] [Accepted: 09/23/2024] [Indexed: 10/02/2024] Open
Abstract
The ER is the organelle of nucleated cells that produces lipids, sugars, and proteins. More than 20 ER-resident members of the protein disulfide isomerase (PDI) family regulate formation, isomerization, and disassembly of covalent bonds in newly synthesized polypeptides. The PDI family includes few membrane-bound members. Among these, TMX1, TMX2, TMX3, TMX4, and TMX5 belong to the thioredoxin-related transmembrane (TMX) protein family. TMX5 is the least-known member of the family. Here, we establish that TMX5 covalently engages via its active site cysteine residue at position 220 a subset of secretory proteins, mainly single- and multipass Golgi-resident polypeptides. TMX5 also interacts non-covalently, and covalently, via non-catalytic cysteine residues, with the PDI family members PDI, ERp57, and ERp44. The association between TMX5 and ERp44 requires formation of a mixed disulfide between the catalytic cysteine residue 29 of ERp44 and the non-catalytic cysteine residues 114 and/or 124 of TMX5 and controls the ER localization of TMX5 in pre-Golgi compartments. Thus, TMX5 belongs to the family of proteins including Ero1α, Ero1β, Prx4, ERAP1, and SUMF1 that operate in pre-Golgi compartments but lack localization sequences required to position themselves and rely on ERp44 engagement for proper intercompartmental distribution.
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Affiliation(s)
- Tatiana Soldà
- https://ror.org/05gfswd81 Università della Svizzera italiana, Institute for Research in Biomedicine, Bellinzona, Switzerland
| | - Carmela Galli
- https://ror.org/05gfswd81 Università della Svizzera italiana, Institute for Research in Biomedicine, Bellinzona, Switzerland
| | - Concetta Guerra
- https://ror.org/05gfswd81 Università della Svizzera italiana, Institute for Research in Biomedicine, Bellinzona, Switzerland
| | - Carolin Hoefner
- https://ror.org/05gfswd81 Università della Svizzera italiana, Institute for Research in Biomedicine, Bellinzona, Switzerland
- Department of Biology, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Maurizio Molinari
- https://ror.org/05gfswd81 Università della Svizzera italiana, Institute for Research in Biomedicine, Bellinzona, Switzerland
- School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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2
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Oliveira PVS, Dalla Torre M, Debbas V, Orsi A, Laurindo FRM, Sitia R. Transport of protein disulfide isomerase from the endoplasmic reticulum to the extracellular space without passage through the Golgi complex. J Biol Chem 2024; 300:107536. [PMID: 38971317 PMCID: PMC11342103 DOI: 10.1016/j.jbc.2024.107536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Revised: 05/29/2024] [Accepted: 06/21/2024] [Indexed: 07/08/2024] Open
Abstract
Protein disulfide isomerase-A1 (PDIA1) is a master regulator of oxidative protein folding and proteostasis in the endoplasmic reticulum (ER). However, PDIA1 can reach the extracellular space, impacting thrombosis and other pathophysiological phenomena. Whether PDIA1 is externalized via passive release or active secretion is not known. To investigate how PDIA1 negotiates its export, we generated a tagged variant that undergoes N-glycosylation in the ER (Glyco-PDIA1). Addition of N-glycans does not alter its enzymatic functions. Upon either deletion of its KDEL ER-localization motif or silencing of KDEL receptors, Glyco-PDIA1 acquires complex glycans in the Golgi and is secreted. In control cells, however, Glyco-PDIA1 is released with endoglycosidase-H sensitive glycans, implying that it does not follow the classical ER-Golgi route nor does it encounter glycanases in the cytosol. Extracellular Glyco-PDIA1 is more abundant than actin, lactate dehydrogenase, or other proteins released by damaged or dead cells, suggesting active transport through a Golgi-independent route. The strategy we describe herein can be extended to dissect how select ER-residents reach the extracellular space.
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Affiliation(s)
- Percillia Victoria Santos Oliveira
- Division of Genetics and Cell Biology Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, Milan, Italy; Laboratorio de Biologia Vascular, LIM-64 (Biologia Cardiovascular Translacional), Instituto do Coração (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Marco Dalla Torre
- Division of Genetics and Cell Biology Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Victor Debbas
- Laboratorio de Biologia Vascular, LIM-64 (Biologia Cardiovascular Translacional), Instituto do Coração (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | - Andrea Orsi
- Division of Genetics and Cell Biology Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Francisco Rafael Martins Laurindo
- Laboratorio de Biologia Vascular, LIM-64 (Biologia Cardiovascular Translacional), Instituto do Coração (InCor), Hospital das Clinicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
| | - Roberto Sitia
- Division of Genetics and Cell Biology Vita-Salute San Raffaele University and IRCCS San Raffaele Scientific Institute, Milan, Italy.
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3
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Hamilton S, Terentyev D. ER stress and calcium-dependent arrhythmias. Front Physiol 2022; 13:1041940. [PMID: 36425292 PMCID: PMC9679650 DOI: 10.3389/fphys.2022.1041940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 10/24/2022] [Indexed: 11/11/2022] Open
Abstract
The sarcoplasmic reticulum (SR) plays the key role in cardiac function as the major source of Ca2+ that activates cardiomyocyte contractile machinery. Disturbances in finely-tuned SR Ca2+ release by SR Ca2+ channel ryanodine receptor (RyR2) and SR Ca2+ reuptake by SR Ca2+-ATPase (SERCa2a) not only impair contraction, but also contribute to cardiac arrhythmia trigger and reentry. Besides being the main Ca2+ storage organelle, SR in cardiomyocytes performs all the functions of endoplasmic reticulum (ER) in other cell types including protein synthesis, folding and degradation. In recent years ER stress has become recognized as an important contributing factor in many cardiac pathologies, including deadly ventricular arrhythmias. This brief review will therefore focus on ER stress mechanisms in the heart and how these changes can lead to pro-arrhythmic defects in SR Ca2+ handling machinery.
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Affiliation(s)
- Shanna Hamilton
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, United States,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States,*Correspondence: Shanna Hamilton,
| | - Dmitry Terentyev
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, United States,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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4
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Ugalde JM, Aller I, Kudrjasova L, Schmidt RR, Schlößer M, Homagk M, Fuchs P, Lichtenauer S, Schwarzländer M, Müller-Schüssele SJ, Meyer AJ. Endoplasmic reticulum oxidoreductin provides resilience against reductive stress and hypoxic conditions by mediating luminal redox dynamics. THE PLANT CELL 2022; 34:4007-4027. [PMID: 35818121 PMCID: PMC9516139 DOI: 10.1093/plcell/koac202] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 07/05/2022] [Indexed: 05/28/2023]
Abstract
Oxidative protein folding in the endoplasmic reticulum (ER) depends on the coordinated action of protein disulfide isomerases and ER oxidoreductins (EROs). Strict dependence of ERO activity on molecular oxygen as the final electron acceptor implies that oxidative protein folding and other ER processes are severely compromised under hypoxia. Here, we isolated viable Arabidopsis thaliana ero1 ero2 double mutants that are highly sensitive to reductive stress and hypoxia. To elucidate the specific redox dynamics in the ER in vivo, we expressed the glutathione redox potential (EGSH) sensor Grx1-roGFP2iL-HDEL with a midpoint potential of -240 mV in the ER of Arabidopsis plants. We found EGSH values of -241 mV in wild-type plants, which is less oxidizing than previously estimated. In the ero1 ero2 mutants, luminal EGSH was reduced further to -253 mV. Recovery to reductive ER stress induced by dithiothreitol was delayed in ero1 ero2. The characteristic signature of EGSH dynamics in the ER lumen triggered by hypoxia was affected in ero1 ero2 reflecting a disrupted balance of reductive and oxidizing inputs, including nascent polypeptides and glutathione entry. The ER redox dynamics can now be dissected in vivo, revealing a central role of EROs as major redox integrators to promote luminal redox homeostasis.
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Affiliation(s)
| | - Isabel Aller
- INRES-Chemical Signalling, University of Bonn, D-53113 Bonn, Germany
| | - Lika Kudrjasova
- INRES-Chemical Signalling, University of Bonn, D-53113 Bonn, Germany
| | - Romy R Schmidt
- Plant Biotechnology, Bielefeld University, D-33615 Bielefeld, Germany
| | - Michelle Schlößer
- INRES-Chemical Signalling, University of Bonn, D-53113 Bonn, Germany
| | - Maria Homagk
- INRES-Chemical Signalling, University of Bonn, D-53113 Bonn, Germany
| | | | - Sophie Lichtenauer
- Institute for Biology and Biotechnology of Plants, University of Münster, D-48143 Münster, Germany
| | - Markus Schwarzländer
- Institute for Biology and Biotechnology of Plants, University of Münster, D-48143 Münster, Germany
| | - Stefanie J Müller-Schüssele
- INRES-Chemical Signalling, University of Bonn, D-53113 Bonn, Germany
- Molecular Botany, Department of Biology, TU Kaiserslautern, D-67663, Kaiserslautern, Germany
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Liu P, Wang X, Sun Y, Zhao H, Cheng F, Wang J, Yang F, Hu J, Zhang H, Wang CC, Wang L. SARS-CoV-2 ORF8 reshapes the ER through forming mixed disulfides with ER oxidoreductases. Redox Biol 2022; 54:102388. [PMID: 35792438 PMCID: PMC9239706 DOI: 10.1016/j.redox.2022.102388] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/18/2022] [Accepted: 06/26/2022] [Indexed: 01/22/2023] Open
Abstract
The replication machinery of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is closely associated with the endoplasmic reticulum (ER) in host cells. Activation of the unfolded protein response (UPR) is a strategy hijacked by coronavirus to facilitate its replication and suppress host innate immunity. Here, we have found that SARS-CoV-2 ORF8 protein accumulates in the ER and escapes the degradation system by forming mixed disulfide complexes with ER oxidoreductases. ORF8 induces the activation of three UPR pathways through targeting key UPR components, remodels ER morphology and accelerates protein trafficking. Moreover, small molecule reducing agents release ORF8 from the mixed disulfide complexes and facilitate its degradation, therefore mitigate ER stress. Our study reveals a unique mechanism by which SARS-CoV-2 ORF8 escapes degradation by host cells and regulates ER reshaping. Targeting ORF8-involved mixed disulfide complexes could be a new strategy to alleviate SARS-CoV-2 induced ER stress and related diseases. SARS-CoV-2 ORF8 protein accumulates in the ER through forming mixed disulfide complexes. Two key protein disulfide isomerases, PDI and ERp44, are main targets of ORF8. ORF8 induces ER stress, remodels the ER and accelerates protein trafficking. Small molecule reducing agents facilitates the degradation of ORF8 and mitigates ER stress.
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Affiliation(s)
- Ping Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xi Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Yiwei Sun
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hongyu Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Fang Cheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jifeng Wang
- Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Fuquan Yang
- Laboratory of Proteomics, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Junjie Hu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chih-Chen Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lei Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
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6
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Gansemer ER, Rutkowski DT. Pathways Linking Nicotinamide Adenine Dinucleotide Phosphate Production to Endoplasmic Reticulum Protein Oxidation and Stress. Front Mol Biosci 2022; 9:858142. [PMID: 35601828 PMCID: PMC9114485 DOI: 10.3389/fmolb.2022.858142] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
The endoplasmic reticulum (ER) lumen is highly oxidizing compared to other subcellular compartments, and maintaining the appropriate levels of oxidizing and reducing equivalents is essential to ER function. Both protein oxidation itself and other essential ER processes, such as the degradation of misfolded proteins and the sequestration of cellular calcium, are tuned to the ER redox state. Simultaneously, nutrients are oxidized in the cytosol and mitochondria to power ATP generation, reductive biosynthesis, and defense against reactive oxygen species. These parallel needs for protein oxidation in the ER and nutrient oxidation in the cytosol and mitochondria raise the possibility that the two processes compete for electron acceptors, even though they occur in separate cellular compartments. A key molecule central to both processes is NADPH, which is produced by reduction of NADP+ during nutrient catabolism and which in turn drives the reduction of components such as glutathione and thioredoxin that influence the redox potential in the ER lumen. For this reason, NADPH might serve as a mediator linking metabolic activity to ER homeostasis and stress, and represent a novel form of mitochondria-to-ER communication. In this review, we discuss oxidative protein folding in the ER, NADPH generation by the major pathways that mediate it, and ER-localized systems that can link the two processes to connect ER function to metabolic activity.
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Affiliation(s)
- Erica R. Gansemer
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - D. Thomas Rutkowski
- Department of Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
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7
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Hamilton S, Terentyeva R, Bogdanov V, Kim TY, Perger F, Yan J, Ai X, Carnes CA, Belevych AE, George CH, Davis JP, Gyorke S, Choi BR, Terentyev D. Ero1α-Dependent ERp44 Dissociation From RyR2 Contributes to Cardiac Arrhythmia. Circ Res 2022; 130:711-724. [PMID: 35086342 PMCID: PMC8893133 DOI: 10.1161/circresaha.121.320531] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Oxidative stress in cardiac disease promotes proarrhythmic disturbances in Ca2+ homeostasis, impairing luminal Ca2+ regulation of the sarcoplasmic reticulum (SR) Ca2+ release channel, the RyR2 (ryanodine receptor), and increasing channel activity. However, exact mechanisms underlying redox-mediated increase of RyR2 function in cardiac disease remain elusive. We tested whether the oxidoreductase family of proteins that dynamically regulate the oxidative environment within the SR are involved in this process. METHODS A rat model of hypertrophy induced by thoracic aortic banding (TAB) was used for ex vivo whole heart optical mapping and for Ca2+ and reactive oxygen species imaging in isolated ventricular myocytes (VMs). RESULTS The SR-targeted reactive oxygen species biosensor ERroGFP showed increased intra-SR oxidation in TAB VMs that was associated with increased expression of Ero1α (endoplasmic reticulum oxidoreductase 1 alpha). Pharmacological (EN460) or genetic Ero1α inhibition normalized SR redox state, increased Ca2+ transient amplitude and SR Ca2+ content, and reduced proarrhythmic spontaneous Ca2+ waves in TAB VMs under β-adrenergic stimulation (isoproterenol). Ero1α overexpression in Sham VMs had opposite effects. Ero1α inhibition attenuated Ca2+-dependent ventricular tachyarrhythmias in TAB hearts challenged with isoproterenol. Experiments in TAB VMs and human embryonic kidney 293 cells expressing human RyR2 revealed that an Ero1α-mediated increase in SR Ca2+-channel activity involves dissociation of intraluminal protein ERp44 (endoplasmic reticulum protein 44) from the RyR2 complex. Site-directed mutagenesis and molecular dynamics simulations demonstrated a novel redox-sensitive association of ERp44 with RyR2 mediated by intraluminal cysteine 4806. ERp44-RyR2 association in TAB VMs was restored by Ero1α inhibition, but not by reducing agent dithiothreitol, as hypo-oxidation precludes formation of covalent bond between RyR2 and ERp44. CONCLUSIONS A novel axis of intraluminal interaction between RyR2, ERp44, and Ero1α has been identified. Ero1α inhibition exhibits promising therapeutic potential by stabilizing RyR2-ERp44 complex, thereby reducing spontaneous Ca2+ release and Ca2+-dependent tachyarrhythmias in hypertrophic hearts, without causing hypo-oxidative stress in the SR.
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Affiliation(s)
- Shanna Hamilton
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Radmila Terentyeva
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Vladimir Bogdanov
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Tae Yun Kim
- Cardiovascular Research Center, Rhode Island Hospital, Department of Medicine, Warren Alpert Medical School of Brown University, Providence, RI (T.Y.K., B.-R.C.)
| | - Fruzsina Perger
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Jiajie Yan
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Xun Ai
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Cynthia A. Carnes
- College of Pharmacy (C.A.C.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Andriy E. Belevych
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | | | - Jonathan P. Davis
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Sandor Gyorke
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
| | - Bum-Rak Choi
- Cardiovascular Research Center, Rhode Island Hospital, Department of Medicine, Warren Alpert Medical School of Brown University, Providence, RI (T.Y.K., B.-R.C.)
| | - Dmitry Terentyev
- Department of Physiology and Cell Biology (S.H., R.T., V.B., F.P., J.Y., X.A., A.E.B., J.P.D., S.G., D.T.), The Ohio State University.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus (S.H., R.T., V.B., F.P., J.Y., X.A., C.A.C., A.E.B., J.P.D., S.G., D.T.)
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8
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Law ME, Yaaghubi E, Ghilardi AF, Davis BJ, Ferreira RB, Koh J, Chen S, DePeter SF, Schilson CM, Chiang CW, Heldermon CD, Nørgaard P, Castellano RK, Law BK. Inhibitors of ERp44, PDIA1, and AGR2 induce disulfide-mediated oligomerization of Death Receptors 4 and 5 and cancer cell death. Cancer Lett 2022; 534:215604. [PMID: 35247515 DOI: 10.1016/j.canlet.2022.215604] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/27/2022] [Accepted: 02/21/2022] [Indexed: 01/08/2023]
Abstract
Breast cancer mortality remains unacceptably high, indicating a need for safer and more effective therapeutic agents. Disulfide bond Disrupting Agents (DDAs) were previously identified as a novel class of anticancer compounds that selectively kill cancers that overexpress the Epidermal Growth Factor Receptor (EGFR) or its family member HER2. DDAs kill EGFR+ and HER2+ cancer cells via the parallel downregulation of EGFR, HER2, and HER3 and activation/oligomerization of Death Receptors 4 and 5 (DR4/5). However, the mechanisms by which DDAs mediate these effects are unknown. Affinity purification analyses employing biotinylated-DDAs reveal that the Protein Disulfide Isomerase (PDI) family members AGR2, PDIA1, and ERp44 are DDA target proteins. Further analyses demonstrate that shRNA-mediated knockdown of AGR2 and ERp44, or expression of ERp44 mutants, enhance basal DR5 oligomerization. DDA treatment of breast cancer cells disrupts PDIA1 and ERp44 mixed disulfide bonds with their client proteins. Together, the results herein reveal DDAs as the first small molecule, active site inhibitors of AGR2 and ERp44, and demonstrate roles for AGR2 and ERp44 in regulating the activity, stability, and localization of DR4 and DR5, and activation of Caspase 8.
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Affiliation(s)
- Mary E Law
- Department of Pharmacology & Therapeutics, University of Florida, Gainesville, FL, 32610, USA
| | - Elham Yaaghubi
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | - Amanda F Ghilardi
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | - Bradley J Davis
- Department of Pharmacology & Therapeutics, University of Florida, Gainesville, FL, 32610, USA
| | - Renan B Ferreira
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | - Jin Koh
- Proteomics and Mass Spectrometry Facility, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, 32610, USA
| | - Sixue Chen
- Proteomics and Mass Spectrometry Facility, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, 32610, USA; Department of Biology, Genetics Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Sadie F DePeter
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | | | - Chi-Wu Chiang
- Institute of Molecular Medicine, College of Medicine and Center for Infectious Disease and Signaling Research, National Cheng Kung University, Tainan, Taiwan
| | - Coy D Heldermon
- Department of Medicine, University of Florida, Gainesville, FL, 32610, USA; UF-Health Cancer Center, University of Florida, Gainesville, FL, 32610, USA
| | - Peter Nørgaard
- Department of Pathology, Copenhagen University Hospital Herlev, DK, 2730, Herlev, Denmark
| | - Ronald K Castellano
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA; UF-Health Cancer Center, University of Florida, Gainesville, FL, 32610, USA.
| | - Brian K Law
- Department of Pharmacology & Therapeutics, University of Florida, Gainesville, FL, 32610, USA; UF-Health Cancer Center, University of Florida, Gainesville, FL, 32610, USA.
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9
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Bi Y, Yang Z, Jin M, Zhai K, Wang J, Mao Y, Liu Y, Ding M, Wang H, Wang F, Cai H, Ji G. ERp44 is required for endocardial cushion development by regulating VEGFA secretion in myocardium. Cell Prolif 2022; 55:e13179. [PMID: 35088919 PMCID: PMC8891561 DOI: 10.1111/cpr.13179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/22/2021] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES Endocardial cushions are precursors of the valve septum complex that separates the four heart chambers. Several genes have been implicated in the development of endocardial cushions. Specifically, ERp44 has been found to play a role in the early secretory pathway, but its function in heart development has not been well studied. MATERIALS AND METHODS In this study, we established conditional and tissue-specific knockout mouse models. The morphology, survival rate, the development of heart and endocardial cushion were under evaluation. The relationship between ERp44 and VEGFA was investigated by transcriptome, qPCR, WB, immunofluorescence and immunohistochemistry. RESULTS ERp44 knockout (KO) mice were smaller in size, and most mice died during early postnatal life. KO hearts exhibited the typical phenotypes of congenital heart diseases, such as abnormal heart shapes and severe septal and valvular defects. Similar phenotypes were found in cTNT-Cre+/- ; ERp44fl / fl mice, which indicated that myocardial ERp44 principally controls endocardial cushion formation. Further studies demonstrated that the deletion of ERp44 significantly decreased the proliferation of cushion cells and impaired the endocardial-mesenchymal transition (EndMT), which was followed by endocardial cushion dysplasia. Finally, we found that ERp44 was directly bound to VEGFA and controlled its release, further regulating EndMT. CONCLUSION We demonstrated that ERp44 plays a specific role in heart development. ERp44 contributes to the development of the endocardial cushion by affecting VEGFA-mediated EndMT.
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Affiliation(s)
- Youkun Bi
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Zhiguang Yang
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Meng Jin
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Kui Zhai
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Jun Wang
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Yang Mao
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Yang Liu
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Mingqin Ding
- National Institute of Biological SciencesBeijingChina
| | - Huiwen Wang
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
| | - Fengchao Wang
- National Institute of Biological SciencesBeijingChina
| | - Hong Cai
- Department of DermatologyAir Force Medical CenterPLABeijingChina
| | - Guangju Ji
- Key Laboratory of Interdisciplinary ResearchInstitute of BiophysicsChinese Academy of SciencesBeijingChina
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10
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Bi Y, Chang Y, Liu Q, Mao Y, Zhai K, Zhou Y, Jiao R, Ji G. ERp44/CG9911 promotes fat storage in Drosophila adipocytes by regulating ER Ca 2+ homeostasis. Aging (Albany NY) 2021; 13:15013-15031. [PMID: 34031268 PMCID: PMC8221293 DOI: 10.18632/aging.203063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 03/27/2021] [Indexed: 12/12/2022]
Abstract
Fat storage is one of the important strategies employed in regulating energy homeostasis. Impaired lipid storage causes metabolic disorders in both mammals and Drosophila. In this study, we report CG9911, the Drosophila homolog of ERp44 (endoplasmic reticulum protein 44) plays a role in regulating adipose tissue fat storage. Using the CRISPR/Cas9 system, we generated a CG9911 mutant line deleting 5 bp of the coding sequence. The mutant flies exhibit phenotypes of lower bodyweight, fewer lipid droplets, reduced TAG level and increased expression of lipolysis related genes. The increased lipolysis phenotype is enhanced in the presence of ER stresses and suppressed by a reduction of the ER Ca2+. Moreover, loss of CG9911 per se results in a decrease of ER Ca2+ in the fat body. Together, our results reveal a novel function of CG9911 in promoting fat storage via regulating ER Ca2+ signal in Drosophila.
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Affiliation(s)
- Youkun Bi
- Key Laboratory of Interdisciplinary Research, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Chang
- Key Laboratory of Interdisciplinary Research, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qun Liu
- Key Laboratory of Interdisciplinary Research, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Mao
- Key Laboratory of Interdisciplinary Research, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kui Zhai
- Key Laboratory of Interdisciplinary Research, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuanli Zhou
- Key Laboratory of Protein and Peptide Pharmaceutical, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Renjie Jiao
- Key Laboratory of Interdisciplinary Research, Chinese Academy of Sciences, Beijing 100101, China.,Sino-French Hoffmann Institute, School of Basic Medical Science, Guangzhou Medical University, Guangzhou 510182, China
| | - Guangju Ji
- Key Laboratory of Interdisciplinary Research, Chinese Academy of Sciences, Beijing 100101, China
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11
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Hampe L, Harris PWR, Rushton B, Radjainia M, Brimble MA, Mitra AK. Engineering a stable complex of
ERp44
with a designed peptide ligand for analyzing the mode of interaction of
ERp44
with its clients. Pept Sci (Hoboken) 2021. [DOI: 10.1002/pep2.24230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Lutz Hampe
- School of Biological Sciences The University of Auckland Auckland New Zealand
| | - Paul W. R. Harris
- School of Biological Sciences The University of Auckland Auckland New Zealand
- School of Chemical Sciences The University of Auckland Auckland New Zealand
| | - Ben Rushton
- School of Biological Sciences The University of Auckland Auckland New Zealand
- Bernhard‐Nocht Institute for Tropical Medicine Bernhard‐Nocht‐Straße 74, 20359 Hamburg Germany
| | - Mazdak Radjainia
- School of Biological Sciences The University of Auckland Auckland New Zealand
- Thermo Fisher Scientific Eindhoven The Netherlands
| | - Margaret A. Brimble
- School of Biological Sciences The University of Auckland Auckland New Zealand
- School of Chemical Sciences The University of Auckland Auckland New Zealand
| | - Alok K. Mitra
- School of Biological Sciences The University of Auckland Auckland New Zealand
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12
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LncRNAs induce oxidative stress and spermatogenesis by regulating endoplasmic reticulum genes and pathways. Aging (Albany NY) 2021; 13:13764-13787. [PMID: 34001678 PMCID: PMC8202879 DOI: 10.18632/aging.202971] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/08/2020] [Indexed: 12/17/2022]
Abstract
Oligozoospermia or low sperm count is a leading cause of male infertility worldwide. Despite decades of work on non-coding RNAs (ncRNAs) as regulators of spermatogenesis, fertilization, and male fertility, the literature on the function of long non-coding RNAs (lncRNAs) in human oligozoospermia is scarce. We integrated lncRNA and mRNA sequencing data from 12 human normozoospermic and oligozoospermic samples and comprehensively analyzed the function of differentially expressed lncRNAs (DE lncRNAs) and mRNAs (DE mRNAs) in male infertility. The target genes of DE lncRNAs were identified using a Gaussian graphical model. Gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways were primarily enriched in protein transport and localization to the endoplasmic reticulum (ER). The lncRNA–mRNA co-expression network revealed cis- and trans-regulated target genes of lncRNAs. The transcriptome data implicated DE lncRNAs and DE mRNAs and their target genes in the accumulation of unfolded proteins in sperm ER, PERK-EIF2 pathway-induced ER stress, oxidative stress, and sperm cell apoptosis in individuals with oligozoospermia. These findings suggest that the identified lncRNAs and pathways could serve as effective therapeutic targets for male infertility.
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13
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A virtuous cycle operated by ERp44 and ERGIC-53 guarantees proteostasis in the early secretory compartment. iScience 2021; 24:102244. [PMID: 33763635 PMCID: PMC7973864 DOI: 10.1016/j.isci.2021.102244] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/01/2021] [Accepted: 02/25/2021] [Indexed: 01/13/2023] Open
Abstract
The composition of the secretome depends on the combined action of cargo receptors that facilitate protein transport and sequential checkpoints that restrict it to native conformers. Acting after endoplasmic reticulum (ER)-resident chaperones, ERp44 retrieves its clients from downstream compartments. To guarantee efficient quality control, ERp44 should exit the ER as rapidly as its clients, or more. Here, we show that appending ERp44 to different cargo proteins increases their secretion rates. ERp44 binds the cargo receptor ER-Golgi intermediate compartment (ERGIC)-53 in the ER to negotiate preferential loading into COPII vesicles. Silencing ERGIC-53, or competing for its COPII binding with 4-phenylbutyrate, causes secretion of Prdx4, an enzyme that relies on ERp44 for intracellular localization. In more acidic, zinc-rich downstream compartments, ERGIC-53 releases its clients and ERp44, which can bind and retrieve non-native conformers via KDEL receptors. By coupling the transport of cargoes and inspector proteins, cells ensure efficiency and fidelity of secretion.
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14
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PDI-Regulated Disulfide Bond Formation in Protein Folding and Biomolecular Assembly. Molecules 2020; 26:molecules26010171. [PMID: 33396541 PMCID: PMC7794689 DOI: 10.3390/molecules26010171] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/25/2020] [Accepted: 12/28/2020] [Indexed: 02/06/2023] Open
Abstract
Disulfide bonds play a pivotal role in maintaining the natural structures of proteins to ensure their performance of normal biological functions. Moreover, biological molecular assembly, such as the gluten network, is also largely dependent on the intermolecular crosslinking via disulfide bonds. In eukaryotes, the formation and rearrangement of most intra- and intermolecular disulfide bonds in the endoplasmic reticulum (ER) are mediated by protein disulfide isomerases (PDIs), which consist of multiple thioredoxin-like domains. These domains assist correct folding of proteins, as well as effectively prevent the aggregation of misfolded ones. Protein misfolding often leads to the formation of pathological protein aggregations that cause many diseases. On the other hand, glutenin aggregation and subsequent crosslinking are required for the formation of a rheologically dominating gluten network. Herein, the mechanism of PDI-regulated disulfide bond formation is important for understanding not only protein folding and associated diseases, but also the formation of functional biomolecular assembly. This review systematically illustrated the process of human protein disulfide isomerase (hPDI) mediated disulfide bond formation and complemented this with the current mechanism of wheat protein disulfide isomerase (wPDI) catalyzed formation of gluten networks.
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15
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Tempio T, Anelli T. The pivotal role of ERp44 in patrolling protein secretion. J Cell Sci 2020; 133:133/21/jcs240366. [PMID: 33173013 DOI: 10.1242/jcs.240366] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Interactions between protein ligands and receptors are the main language of intercellular communication; hence, how cells select proteins to be secreted or presented on the plasma membrane is a central concern in cell biology. A series of checkpoints are located along the secretory pathway, which ensure the fidelity of such protein signals (quality control). Proteins that pass the checkpoints operated in the endoplasmic reticulum (ER) by the binding immunoglobulin protein (BiP; also known as HSPA5 and GRP78) and the calnexin-calreticulin systems, must still overcome additional scrutiny in the ER-Golgi intermediate compartment (ERGIC) and the Golgi. One of the main players of this process in all metazoans is the ER-resident protein 44 (ERp44); by cycling between the ER and the Golgi, ERp44 controls the localization of key enzymes designed to act in the ER but that are devoid of suitable localization motifs. ERp44 also patrols the secretion of correctly assembled disulfide-linked oligomeric proteins. Here, we discuss the mechanisms driving ERp44 substrate recognition, with important consequences on the definition of 'thiol-mediated quality control'. We also describe how pH and zinc gradients regulate the functional cycle of ERp44, coupling quality control and membrane trafficking along the early secretory compartment.
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Affiliation(s)
- Tiziana Tempio
- Division of Genetics and Cell Biology, Vita-Salute San Raffaele University, Milan 20132, Italy.,IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Tiziana Anelli
- Division of Genetics and Cell Biology, Vita-Salute San Raffaele University, Milan 20132, Italy .,IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
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16
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Sicari D, Chatziioannou A, Koutsandreas T, Sitia R, Chevet E. Role of the early secretory pathway in SARS-CoV-2 infection. J Cell Biol 2020; 219:e202006005. [PMID: 32725137 PMCID: PMC7480111 DOI: 10.1083/jcb.202006005] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/03/2020] [Accepted: 07/07/2020] [Indexed: 12/17/2022] Open
Abstract
Similar to other RNA viruses, SARS-CoV-2 must (1) enter a target/host cell, (2) reprogram it to ensure its replication, (3) exit the host cell, and (4) repeat this cycle for exponential growth. During the exit step, the virus hijacks the sophisticated machineries that host cells employ to correctly fold, assemble, and transport proteins along the exocytic pathway. Therefore, secretory pathway-mediated assemblage and excretion of infective particles represent appealing targets to reduce the efficacy of virus biogenesis, if not to block it completely. Here, we analyze and discuss the contribution of the molecular machines operating in the early secretory pathway in the biogenesis of SARS-CoV-2 and their relevance for potential antiviral targeting. The fact that these molecular machines are conserved throughout evolution, together with the redundancy and tissue specificity of their components, provides opportunities in the search for unique proteins essential for SARS-CoV-2 biology that could also be targeted with therapeutic objectives. Finally, we provide an overview of recent evidence implicating proteins of the early secretory pathway as potential antiviral targets with effective therapeutic applications.
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Affiliation(s)
- Daria Sicari
- Inserm U1242, Université de Rennes, Rennes, France
- Centre de Lutte Contre le Cancer Eugène Marquis, Rennes, France
- Università Vita-Salute San Raffaele, Milan, Italy
| | - Aristotelis Chatziioannou
- e-NIOS Applications PC, Kallithea-Athens, Greece
- Center of Systems Biology, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Theodoros Koutsandreas
- e-NIOS Applications PC, Kallithea-Athens, Greece
- Center of Systems Biology, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | | | - Eric Chevet
- Inserm U1242, Université de Rennes, Rennes, France
- Centre de Lutte Contre le Cancer Eugène Marquis, Rennes, France
- Università Vita-Salute San Raffaele, Milan, Italy
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17
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Uddin MS, Tewari D, Sharma G, Kabir MT, Barreto GE, Bin-Jumah MN, Perveen A, Abdel-Daim MM, Ashraf GM. Molecular Mechanisms of ER Stress and UPR in the Pathogenesis of Alzheimer's Disease. Mol Neurobiol 2020; 57:2902-2919. [PMID: 32430843 DOI: 10.1007/s12035-020-01929-y] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 05/01/2020] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease involving aggregation of misfolded proteins inside the neuron causing prolonged cellular stress. The neuropathological hallmarks of AD include the formation of senile plaques and neurofibrillary tangles in specific brain regions that lead to synaptic loss and neuronal death. The exact mechanism of neuron dysfunction in AD remains obscure. In recent years, endoplasmic reticulum (ER) dysfunction has been implicated in neuronal degeneration seen in AD. Apart from AD, many other diseases also involve misfolded proteins aggregations in the ER, a condition referred to as ER stress. The response of the cell to ER stress is to activate a group of signaling pathways called unfolded protein response (UPR) that stimulates a particular transcriptional program to restore ER function and ensure cell survival. ER stress also involves the generation of reactive oxygen species (ROS) that, together with mitochondrial ROS and decreased effectiveness of antioxidant mechanisms, producing a condition of chronic oxidative stress. The unfolded proteins may not always produce a response that leads to the restoration of cellular functions, but they may also lead to inflammation by a set of different pathways with deleterious consequences. In this review, we extensively discuss the role of ER stress and how to target it using different pharmacological approaches in AD development and onset.
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Affiliation(s)
- Md Sahab Uddin
- Department of Pharmacy, Southeast University, Dhaka, Bangladesh.
- Pharmakon Neuroscience Research Network, Dhaka, Bangladesh.
| | - Devesh Tewari
- Department of Pharmacognosy, School of Pharmaceutical Sciences, Lovely Professional University, Phagwara, Punjab, India
| | - Gaurav Sharma
- Department of Physiology, AIIMS Jodhpur, Jodhpur, India
| | | | - George E Barreto
- Department of Biological Sciences, University of Limerick, Limerick, Ireland.
- Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile.
| | - May N Bin-Jumah
- Department of Biology, College of Science, Princess Nourah bint Abdulrahman University, Riyadh 11474, Saudi Arabia
| | - Asma Perveen
- Glocal School of Life Sciences, Glocal University, Saharanpur, India
| | - Mohamed M Abdel-Daim
- Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
- Pharmacology Department, Faculty of Veterinary Medicine, Suez Canal University, Ismailia 41522, Egypt
| | - Ghulam Md Ashraf
- King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.
- Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.
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18
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Liyanage D, Omeka W, Lee J. Molecular characterization, host defense mechanisms, and functional analysis of ERp44 from big-belly seahorse: A novel member of the teleost thioredoxin family present in the endoplasmic reticulum. Comp Biochem Physiol B Biochem Mol Biol 2019; 232:31-41. [DOI: 10.1016/j.cbpb.2019.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 01/25/2019] [Accepted: 02/01/2019] [Indexed: 12/22/2022]
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19
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Ushioda R, Nagata K. Redox-Mediated Regulatory Mechanisms of Endoplasmic Reticulum Homeostasis. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a033910. [PMID: 30396882 DOI: 10.1101/cshperspect.a033910] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The endoplasmic reticulum (ER) is a dynamic organelle responsible for many cellular functions in eukaryotic cells. Proper redox conditions in the ER are necessary for the functions of many luminal pathways and the maintenance of homeostasis. The redox environment in the ER is oxidative compared with that of the cytosol, and a network of oxidoreductases centering on the protein disulfide isomerase (PDI)-Ero1α hub complex is constructed for efficient electron transfer. Although these oxidizing environments are advantageous for oxidative folding for protein maturation, electron transfer is strictly controlled by Ero1α structurally and spatially. The ER redox environment shifts to a reductive environment under certain stress conditions. In this review, we focus on the reducing reactions that maintain ER homeostasis and introduce their significance in an oxidative ER environment.
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Affiliation(s)
- Ryo Ushioda
- Laboratory of Molecular and Cellular Biology, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto 603-8555, Japan
| | - Kazuhiro Nagata
- Laboratory of Molecular and Cellular Biology, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto 603-8555, Japan.,Institute for Protein Dynamics, Kyoto Sangyo University, Kyoto 603-8555, Japan
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20
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Rosenberg N, Mor-Cohen R, Sheptovitsky VH, Romanenco O, Hess O, Lahav J. Integrin-mediated cell adhesion requires extracellular disulfide exchange regulated by protein disulfide isomerase. Exp Cell Res 2019; 381:77-85. [PMID: 31042499 DOI: 10.1016/j.yexcr.2019.04.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/26/2019] [Accepted: 04/14/2019] [Indexed: 01/28/2023]
Abstract
Cell adhesion to extracellular matrix, mediated by integrin receptors, is crucial for cell survival. Receptor-ligand interaction involves conformational changes in the integrin by a mechanism not fully elucidated. In addition to several direct evidence that there is disulfide re-arrangement of integrins, we previously demonstrated a role for extracellular thiols and protein disulfide isomerase (PDI) in integrin-mediated functions using platelets as model system. Exploring the possible generality of this mechanism, we now show, using three different nucleated cells which depend on adhesion for survival, that non-penetrating blockers of free thiols inhibit α2β1 and α5β1 integrin-mediated adhesion and that disulfide exchange takes place in that process. Inhibiting extracellular PDI mimics thiol blocking. Transfection with WT or enzymatically inactive PDI increased their membrane expression and enhanced cell adhesion, suggesting that PDI level is a limiting factor and that the chaperone activity of the enzyme contributes to adhesion. Exogenously added PDI also enhanced adhesion, further supporting the limiting factor of the enzyme. These data indicate that: a) Dependence on ecto-sulfhydryls for integrin-mediated adhesion is not exclusive to the platelet; b) PDI is involved in integrin-mediated adhesion, catalyzing disulfide bond exchange; c) PDI enhances cell adhesion by both its oxidoreductase activity and as a chaperone.
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Affiliation(s)
- Nurit Rosenberg
- The Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel-Hashomer and Dept. of Hematology, Sackler School of Medicine, Tel Aviv University, Israel.
| | - Ronit Mor-Cohen
- The Amalia Biron Research Institute of Thrombosis and Hemostasis, Sheba Medical Center, Tel-Hashomer and Dept. of Hematology, Sackler School of Medicine, Tel Aviv University, Israel
| | - Vera Hazan Sheptovitsky
- Hemostasis Laboratory, Rabin Medical Center-Beilinson Hospital, Petah-Tiqva, and Dept. of Human Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Israel
| | - Olga Romanenco
- Hemostasis Laboratory, Rabin Medical Center-Beilinson Hospital, Petah-Tiqva, and Dept. of Human Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Israel
| | - Oded Hess
- Hemostasis Laboratory, Rabin Medical Center-Beilinson Hospital, Petah-Tiqva, and Dept. of Human Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Israel
| | - Judith Lahav
- Hemostasis Laboratory, Rabin Medical Center-Beilinson Hospital, Petah-Tiqva, and Dept. of Human Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Israel
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21
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Zinc regulates ERp44-dependent protein quality control in the early secretory pathway. Nat Commun 2019; 10:603. [PMID: 30723194 PMCID: PMC6363758 DOI: 10.1038/s41467-019-08429-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 01/09/2019] [Indexed: 01/14/2023] Open
Abstract
Zinc ions (Zn2+) are imported into the early secretory pathway by Golgi-resident transporters, but their handling and functions are not fully understood. Here, we show that Zn2+ binds with high affinity to the pH-sensitive chaperone ERp44, modulating its localization and ability to retrieve clients like Ero1α and ERAP1 to the endoplasmic reticulum (ER). Silencing the Zn2+ transporters that uptake Zn2+ into the Golgi led to ERp44 dysfunction and increased secretion of Ero1α and ERAP1. High-resolution crystal structures of Zn2+-bound ERp44 reveal that Zn2+ binds to a conserved histidine-cluster. The consequent large displacements of the regulatory C-terminal tail expose the substrate-binding surface and RDEL motif, ensuring client capture and retrieval. ERp44 also forms Zn2+-bridged homodimers, which dissociate upon client binding. Histidine mutations in the Zn2+-binding sites compromise ERp44 activity and localization. Our findings reveal a role of Zn2+ as a key regulator of protein quality control at the ER-Golgi interface. Zinc ions (Zn2+) are imported by Golgi-resident transporters but the function of zinc in the early secretory pathway has remained unknown. Here the authors find that Zn2+ regulates protein quality control in the early secretory pathway by demonstrating that the pH-sensitive chaperone ERp44 binds Zn2+ and solving the Zn2+-bound ERp44 structure.
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22
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Delaunay-Moisan A, Ponsero A, Toledano MB. Reexamining the Function of Glutathione in Oxidative Protein Folding and Secretion. Antioxid Redox Signal 2017; 27:1178-1199. [PMID: 28791880 DOI: 10.1089/ars.2017.7148] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
SIGNIFICANCE Disturbance of glutathione (GSH) metabolism is a hallmark of numerous diseases, yet GSH functions are poorly understood. One key to this question is to consider its functional compartmentation. GSH is present in the endoplasmic reticulum (ER), where it competes with substrates for oxidation by the oxidative folding machinery, composed in eukaryotes of the thiol oxidase Ero1 and proteins from the disulfide isomerase family (protein disulfide isomerase). Yet, whether GSH is required for proper ER oxidative protein folding is a highly debated question. Recent Advances: Oxidative protein folding has been thoroughly dissected over the past decades, and its actors and their mode of action elucidated. Genetically encoded GSH probes have recently provided an access to subcellular redox metabolism, including the ER. CRITICAL ISSUES Of the few often-contradictory models of the role of GSH in the ER, the most popular suggest it serves as reducing power. Yet, as a reductant, GSH also activates Ero1, which questions how GSH can nevertheless support protein reduction. Hence, whether GSH operates in the ER as a reductant, an oxidant, or just as a "blank" compound mirroring ER/periplasm redox activity is a highly debated question, which is further stimulated by the puzzling occurrence of GSH in the Escherichia coli periplasmic "secretory" compartment, aside from the Dsb thiol-reducing and oxidase pathways. FUTURE DIRECTIONS Addressing the mechanisms controlling GSH traffic in and out of the ER/periplasm and its recycling will help address GSH function in secretion. In addition, as thioredoxin reductase was recently implicated in ER oxidative protein folding, the relative contribution of each of these two reducing pathways should now be addressed. Antioxid. Redox Signal. 27, 1178-1199.
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Affiliation(s)
- Agnès Delaunay-Moisan
- Institute for Integrative Biology of the Cell (I2BC), LSOC, SBIGEM, CEA, CNRS, Université Paris-Sud , Université Paris-Saclay, Gif-sur-Yvette, France
| | - Alise Ponsero
- Institute for Integrative Biology of the Cell (I2BC), LSOC, SBIGEM, CEA, CNRS, Université Paris-Sud , Université Paris-Saclay, Gif-sur-Yvette, France
| | - Michel B Toledano
- Institute for Integrative Biology of the Cell (I2BC), LSOC, SBIGEM, CEA, CNRS, Université Paris-Sud , Université Paris-Saclay, Gif-sur-Yvette, France
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Structural basis of pH-dependent client binding by ERp44, a key regulator of protein secretion at the ER-Golgi interface. Proc Natl Acad Sci U S A 2017; 114:E3224-E3232. [PMID: 28373561 DOI: 10.1073/pnas.1621426114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
ERp44 retrieves some endoplasmic reticulum (ER)-resident enzymes and immature oligomers of secretory proteins from the Golgi. Association of ERp44 with its clients is regulated by pH-dependent mechanisms, but the molecular details are not fully understood. Here we report high-resolution crystal structures of human ERp44 at neutral and weakly acidic pH. These structures reveal key regions in the C-terminal tail (C tail) missing in the original crystal structure, including a regulatory histidine-rich region and a subsequent extended loop. The former region forms a short α-helix (α16), generating a histidine-clustered site (His cluster). At low pH, the three Trx-like domains of ERp44 ("a," "b," and "b'") undergo significant rearrangements, likely induced by protonation of His157 located at the interface between the a and b domains. The α16-helix is partially unwound and the extended loop is disordered in weakly acidic conditions, probably due to electrostatic repulsion between the protonated histidines in the His cluster. Molecular dynamics simulations indicated that helix unwinding enhances the flexibility of the C tail, disrupting its normal hydrogen-bonding pattern. The observed pH-dependent conformational changes significantly enlarge the positively charged regions around the client-binding site of ERp44 at low pH. Mutational analyses showed that ERp44 forms mixed disulfides with specific cysteines residing on negatively charged loop regions of Ero1α. We propose that the protonation states of the essential histidines regulate the ERp44-client interaction by altering the C-tail dynamics and surface electrostatic potential of ERp44.
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24
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Crystal Structure of the ERp44-Peroxiredoxin 4 Complex Reveals the Molecular Mechanisms of Thiol-Mediated Protein Retention. Structure 2016; 24:1755-1765. [PMID: 27642162 DOI: 10.1016/j.str.2016.08.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 07/22/2016] [Accepted: 08/05/2016] [Indexed: 12/23/2022]
Abstract
ERp44 controls the localization and transport of diverse proteins in the early secretory pathway. The mechanisms that allow client recognition and the source of the oxidative power for forming intermolecular disulfides are as yet unknown. Here we present the structure of ERp44 bound to a client, peroxiredoxin 4. Our data reveal that ERp44 binds the oxidized form of peroxiredoxin 4 via thiol-disulfide interchange reactions. The structure explains the redox-dependent recognition and characterizes the essential non-covalent interactions at the interface. The ERp44-Prx4 covalent complexes can be reduced by glutathione and protein disulfide isomerase family members in the ER, allowing the two components to recycle. This work provides insights into the mechanisms of thiol-mediated protein retention and indicates the key roles of ERp44 in this biochemical cycle to optimize oxidative folding and redox homeostasis.
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25
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Jedrychowski MP, Liu L, Laflamme CJ, Karastergiou K, Meshulam T, Ding SY, Wu Y, Lee MJ, Gygi SP, Fried SK, Pilch PF. Adiporedoxin, an upstream regulator of ER oxidative folding and protein secretion in adipocytes. Mol Metab 2015; 4:758-70. [PMID: 26629401 PMCID: PMC4632174 DOI: 10.1016/j.molmet.2015.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 08/28/2015] [Accepted: 09/03/2015] [Indexed: 12/23/2022] Open
Abstract
Objective Adipocytes are robust protein secretors, most notably of adipokines, hormone-like polypeptides, which act in an endocrine and paracrine fashion to affect numerous physiological processes such as energy balance and insulin sensitivity. To understand how such proteins are assembled for secretion we describe the function of a novel endoplasmic reticulum oxidoreductase, adiporedoxin (Adrx). Methods Adrx knockdown and overexpressing 3T3-L1 murine adipocyte cell lines and a knockout mouse model were used to assess the influence of Adrx on secreted proteins as well as the redox state of ER resident chaperones. The metabolic phenotypes of Adrx null mice were characterized and compared to WT mice. The correlation of Adrx levels BMI, adiponectin levels, and other inflammatory markers from adipose tissue of human subjects was also studied. Results Adiporedoxin functions via a CXXC active site, and is upstream of protein disulfide isomerase whose direct function is disulfide bond formation, and ultimately protein secretion. Over and under expression of Adrx in vitro enhances and reduces, respectively, the secretion of the disulfide-bonded proteins including adiponectin and collagen isoforms. On a chow diet, Adrx null mice have normal body weights, and glucose tolerance, are moderately hyperinsulinemic, have reduced levels of circulating adiponectin and are virtually free of adipocyte fibrosis resulting in a complex phenotype tending towards insulin resistance. Adrx protein levels in human adipose tissue correlate positively with adiponectin levels and negatively with the inflammatory marker phospho-Jun kinase. Conclusion These data support the notion that Adrx plays a critical role in adipocyte biology and in the regulation of mouse and human metabolism via its modulation of adipocyte protein secretion. Adrx is an adipocyte specific, endoplasmic reticulum oxidoreductase upstream of disulfide bond formation. Adrx over and under expression in vitro results enhanced and decreased protein secretion, respectively. Mice lacking Adrx have lower levels of circulating adiponectin and decreased fibrosis. Adrx is expressed in human adipocytes and down regulated in proportion to the level of inflammation.
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Affiliation(s)
- Mark P. Jedrychowski
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
- Department of Cell Biology, Harvard University School of Medicine, 240 Longwood Avenue Boston, MA 02115, USA
| | - Libin Liu
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Collette J. Laflamme
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Kalypso Karastergiou
- Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Tova Meshulam
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Shi-Ying Ding
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Yuanyuan Wu
- Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Mi-Jeong Lee
- Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Steven P. Gygi
- Department of Cell Biology, Harvard University School of Medicine, 240 Longwood Avenue Boston, MA 02115, USA
| | - Susan K. Fried
- Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Paul F. Pilch
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
- Department of Medicine, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
- Corresponding author. Department of Biochemistry, Boston University School of Medicine, 72 E. Concord St., Boston, MA 02118, USA. Tel.: +1 617 638 4044.
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26
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Hampe L, Radjainia M, Xu C, Harris PWR, Bashiri G, Goldstone DC, Brimble MA, Wang Y, Mitra AK. Regulation and Quality Control of Adiponectin Assembly by Endoplasmic Reticulum Chaperone ERp44. J Biol Chem 2015; 290:18111-18123. [PMID: 26060250 DOI: 10.1074/jbc.m115.663088] [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: 05/04/2015] [Indexed: 01/09/2023] Open
Abstract
Adiponectin, a collagenous hormone secreted abundantly from adipocytes, possesses potent antidiabetic and anti-inflammatory properties. Mediated by the conserved Cys(39) located in the variable region of the N terminus, the trimeric (low molecular weight (LMW)) adiponectin subunit assembles into different higher order complexes, e.g. hexamers (middle molecular weight (MMW)) and 12-18-mers (high molecular weight (HMW)), the latter being mostly responsible for the insulin-sensitizing activity of adiponectin. The endoplasmic reticulum (ER) chaperone ERp44 retains adiponectin in the early secretory compartment and tightly controls the oxidative state of Cys(39) and the oligomerization of adiponectin. Using cellular and in vitro assays, we show that ERp44 specifically recognizes the LMW and MMW forms but not the HMW form. Our binding assays with short peptide mimetics of adiponectin suggest that ERp44 intercepts and converts the pool of fully oxidized LMW and MMW adiponectin, but not the HMW form, into reduced trimeric precursors. These ERp44-bound precursors in the cis-Golgi may be transported back to the ER and released to enhance the population of adiponectin intermediates with appropriate oxidative state for HMW assembly, thereby underpinning the process of ERp44 quality control.
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Affiliation(s)
- Lutz Hampe
- School of Biological Science, The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
| | - Mazdak Radjainia
- School of Biological Science, The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
| | - Cheng Xu
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, 999007 Hong Kong, China
| | - Paul W R Harris
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand; Institute for Innovation in Biotechnology, The University of Auckland, 3A Symonds Street, Auckland 1010, New Zealand
| | - Ghader Bashiri
- School of Biological Science, The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
| | - David C Goldstone
- School of Biological Science, The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand
| | - Margaret A Brimble
- School of Chemical Sciences, The University of Auckland, 23 Symonds Street, Auckland 1010, New Zealand; Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand; Institute for Innovation in Biotechnology, The University of Auckland, 3A Symonds Street, Auckland 1010, New Zealand
| | - Yu Wang
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Pharmacology and Pharmacy, The University of Hong Kong, 999007 Hong Kong, China
| | - Alok K Mitra
- School of Biological Science, The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand.
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27
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Okumura M, Kadokura H, Inaba K. Structures and functions of protein disulfide isomerase family members involved in proteostasis in the endoplasmic reticulum. Free Radic Biol Med 2015; 83:314-22. [PMID: 25697777 DOI: 10.1016/j.freeradbiomed.2015.02.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 01/22/2015] [Accepted: 02/09/2015] [Indexed: 12/16/2022]
Abstract
The endoplasmic reticulum (ER) is an essential cellular compartment in which an enormous number of secretory and cell surface membrane proteins are synthesized and subjected to cotranslational or posttranslational modifications, such as glycosylation and disulfide bond formation. Proper maintenance of ER protein homeostasis (sometimes termed proteostasis) is essential to avoid cellular stresses and diseases caused by abnormal proteins. Accumulating knowledge of cysteine-based redox reactions catalyzed by members of the protein disulfide isomerase (PDI) family has revealed that these enzymes play pivotal roles in productive protein folding accompanied by disulfide formation, as well as efficient ER-associated degradation accompanied by disulfide reduction. Each of PDI family members forms a protein-protein interaction with a preferential partner to fulfill a distinct function. Multiple redox pathways that utilize PDIs appear to function synergistically to attain the highest quality and productivity of the ER, even under various stress conditions. This review describes the structures, physiological functions, and cooperative actions of several essential PDIs, and provides important insights into the elaborate proteostatic mechanisms that have evolved in the extremely active and stress-sensitive ER.
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Affiliation(s)
- Masaki Okumura
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Hiroshi Kadokura
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan.
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28
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Anelli T, Sannino S, Sitia R. Proteostasis and "redoxtasis" in the secretory pathway: Tales of tails from ERp44 and immunoglobulins. Free Radic Biol Med 2015; 83:323-30. [PMID: 25744412 DOI: 10.1016/j.freeradbiomed.2015.02.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/20/2015] [Accepted: 02/22/2015] [Indexed: 01/09/2023]
Abstract
In multicellular organisms, some cells are given the task of secreting huge quantities of proteins. To comply with their duty, they generally equip themselves with a highly developed endoplasmic reticulum (ER) and downstream organelles in the secretory pathway. These professional secretors face paramount proteostatic challenges in that they need to couple efficiency and fidelity in their secretory processes. On one hand, stringent quality control (QC) mechanisms operate from the ER onward to check the integrity of the secretome. On the other, the pressure to secrete can be overwhelming, as for instance on antibody-producing cells during infection. Maintaining homeostasis is particularly hard when the products to be released contain disulfide bonds, because oxidative folding entails production of reactive oxygen species. How are redox homeostasis ("redoxtasis") and proteostasis maintained despite the massive fluxes of cargo proteins traversing the pathway? Here we describe recent findings on how ERp44, a multifunctional chaperone of the secretory pathway, can modulate these processes integrating protein QC, redoxtasis, and calcium signaling.
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Affiliation(s)
- Tiziana Anelli
- Divisions of Genetics and Cell Biology, IRCCS Ospedale San Raffaele and Università Vita-Salute San Raffaele, 20132 Milan, Italy
| | - Sara Sannino
- Divisions of Genetics and Cell Biology, IRCCS Ospedale San Raffaele and Università Vita-Salute San Raffaele, 20132 Milan, Italy
| | - Roberto Sitia
- Divisions of Genetics and Cell Biology, IRCCS Ospedale San Raffaele and Università Vita-Salute San Raffaele, 20132 Milan, Italy.
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29
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Gutiérrez T, Simmen T. Endoplasmic reticulum chaperones and oxidoreductases: critical regulators of tumor cell survival and immunorecognition. Front Oncol 2014; 4:291. [PMID: 25386408 PMCID: PMC4209815 DOI: 10.3389/fonc.2014.00291] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 10/07/2014] [Indexed: 12/25/2022] Open
Abstract
Endoplasmic reticulum (ER) chaperones and oxidoreductases are abundant enzymes that mediate the production of fully folded secretory and transmembrane proteins. Resisting the Golgi and plasma membrane-directed “bulk flow,” ER chaperones and oxidoreductases enter retrograde trafficking whenever they are pulled outside of the ER by their substrates. Solid tumors are characterized by the increased production of reactive oxygen species (ROS), combined with reduced blood flow that leads to low oxygen supply and ER stress. Under these conditions, hypoxia and the unfolded protein response upregulate their target genes. When this occurs, ER oxidoreductases and chaperones become important regulators of tumor growth. However, under these conditions, these proteins not only promote the folding of proteins, but also alter the properties of the plasma membrane and hence modulate tumor immune recognition. For instance, high levels of calreticulin serve as an “eat-me” signal on the surface of tumor cells. Conversely, both intracellular and surface BiP/GRP78 promotes tumor growth. Other ER folding assistants able to modulate the properties of tumor tissue include protein disulfide isomerase (PDI), Ero1α and GRP94. Understanding the roles and mechanisms of ER chaperones in regulating tumor cell functions and immunorecognition will lead to important insight for the development of novel cancer therapies.
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Affiliation(s)
- Tomás Gutiérrez
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta , Edmonton, AB , Canada
| | - Thomas Simmen
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta , Edmonton, AB , Canada
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30
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Mossuto MF, Sannino S, Mazza D, Fagioli C, Vitale M, Yoboue ED, Sitia R, Anelli T. A dynamic study of protein secretion and aggregation in the secretory pathway. PLoS One 2014; 9:e108496. [PMID: 25279560 PMCID: PMC4184786 DOI: 10.1371/journal.pone.0108496] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 08/21/2014] [Indexed: 01/08/2023] Open
Abstract
Precise coordination of protein biogenesis, traffic and homeostasis within the early secretory compartment (ESC) is key for cell physiology. As a consequence, disturbances in these processes underlie many genetic and chronic diseases. Dynamic imaging methods are needed to follow the fate of cargo proteins and their interactions with resident enzymes and folding assistants. Here we applied the Halotag labelling system to study the behavior of proteins with different fates and roles in ESC: a chaperone, an ERAD substrate and an aggregation-prone molecule. Exploiting the Halo property of binding covalently ligands labelled with different fluorochromes, we developed and performed non-radioactive pulse and chase assays to follow sequential waves of proteins in ESC, discriminating between young and old molecules at the single cell level. In this way, we could monitor secretion and degradation of ER proteins in living cells. We can also follow the biogenesis, growth, accumulation and movements of protein aggregates in the ESC. Our data show that protein deposits within ESC grow by sequential apposition of molecules up to a given size, after which novel seeds are detected. The possibility of using ligands with distinct optical and physical properties offers a novel possibility to dynamically follow the fate of proteins in the ESC.
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Affiliation(s)
| | - Sara Sannino
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, IT
- Department of Biosciences, Università degli Studi di Milano, Milan, IT
| | - Davide Mazza
- Università Vita-Salute San Raffaele, Milan, IT
- Experimental Imaging Center, IRCCS Ospedale San Raffaele, Milan, IT
| | - Claudio Fagioli
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, IT
| | - Milena Vitale
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, IT
- Università Vita-Salute San Raffaele, Milan, IT
| | - Edgar Djaha Yoboue
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, IT
| | - Roberto Sitia
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, IT
- Università Vita-Salute San Raffaele, Milan, IT
| | - Tiziana Anelli
- Division of Genetics and Cell Biology, IRCCS Ospedale San Raffaele, Milan, IT
- Università Vita-Salute San Raffaele, Milan, IT
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31
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Zhang L, Niu Y, Zhu L, Fang J, Wang X, Wang L, Wang CC. Different interaction modes for protein-disulfide isomerase (PDI) as an efficient regulator and a specific substrate of endoplasmic reticulum oxidoreductin-1α (Ero1α). J Biol Chem 2014; 289:31188-99. [PMID: 25258311 DOI: 10.1074/jbc.m114.602961] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Protein-disulfide isomerase (PDI) and sulfhydryl oxidase endoplasmic reticulum oxidoreductin-1α (Ero1α) constitute the pivotal pathway for oxidative protein folding in the mammalian endoplasmic reticulum (ER). Ero1α oxidizes PDI to introduce disulfides into substrates, and PDI can feedback-regulate Ero1α activity. Here, we show the regulatory disulfide of Ero1α responds to the redox fluctuation in ER very sensitively, relying on the availability of redox active PDI. The regulation of Ero1α is rapidly facilitated by either a or a' catalytic domain of PDI, independent of the substrate binding domain. On the other hand, activated Ero1α specifically binds to PDI via hydrophobic interactions and preferentially catalyzes the oxidation of domain a'. This asymmetry ensures PDI to function simultaneously as an oxidoreductase and an isomerase. In addition, several PDI family members are also characterized to be potent regulators of Ero1α. The novel modes for PDI as a competent regulator and a specific substrate of Ero1α govern efficient and faithful oxidative protein folding and maintain the ER redox homeostasis.
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Affiliation(s)
- Lihui Zhang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yingbo Niu
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Li Zhu
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jingqi Fang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xi'e Wang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and
| | - Lei Wang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and
| | - Chih-chen Wang
- From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and
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32
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Sannino S, Anelli T, Cortini M, Masui S, Degano M, Fagioli C, Inaba K, Sitia R. Progressive quality control of secretory proteins in the early secretory compartment by ERp44. J Cell Sci 2014; 127:4260-9. [PMID: 25097228 DOI: 10.1242/jcs.153239] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
ERp44 is a pH-regulated chaperone of the secretory pathway. In the acidic milieu of the Golgi, its C-terminal tail changes conformation, simultaneously exposing the substrate-binding site for cargo capture and the RDEL motif for ER retrieval through interactions with cognate receptors. Protonation of cysteine 29 in the active site allows tail movements in vitro and in vivo. Here, we show that conserved histidine residues in the C-terminal tail also regulate ERp44 in vivo. Mutants lacking these histidine residues retain substrates more efficiently. Surprisingly, they are also O-glycosylated and partially secreted. Co-expression of client proteins prevents secretion of the histidine mutants, forcing tail opening and RDEL accessibility. Client-induced RDEL exposure allows retrieval of proteins from distinct stations along the secretory pathway, as indicated by the changes in O-glycosylation patterns upon overexpression of different partners. The ensuing gradients might help to optimize folding and assembly of different cargoes. Endogenous ERp44 is O-glycosylated and secreted by human primary endometrial cells, suggesting possible pathophysiological roles of these processes.
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Affiliation(s)
- Sara Sannino
- Divisions of Genetics and Cell Biology and Immunology, Transplantation and Infectious Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy Department of Bioscience, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Tiziana Anelli
- Divisions of Genetics and Cell Biology and Immunology, Transplantation and Infectious Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy Università Vita-Salute San Raffaele, 20132 Milan, Italy
| | - Margherita Cortini
- Divisions of Genetics and Cell Biology and Immunology, Transplantation and Infectious Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy
| | - Shoji Masui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Massimo Degano
- Divisions of Genetics and Cell Biology and Immunology, Transplantation and Infectious Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy Università Vita-Salute San Raffaele, 20132 Milan, Italy
| | - Claudio Fagioli
- Divisions of Genetics and Cell Biology and Immunology, Transplantation and Infectious Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy Università Vita-Salute San Raffaele, 20132 Milan, Italy
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan
| | - Roberto Sitia
- Divisions of Genetics and Cell Biology and Immunology, Transplantation and Infectious Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy Università Vita-Salute San Raffaele, 20132 Milan, Italy
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33
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Biochemical evidence that regulation of Ero1β activity in human cells does not involve the isoform-specific cysteine 262. Biosci Rep 2014; 34:BSR20130124. [PMID: 27919037 PMCID: PMC3971451 DOI: 10.1042/bsr20130124] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/08/2014] [Accepted: 01/28/2014] [Indexed: 12/13/2022] Open
Abstract
In the ER (endoplasmic reticulum) of human cells, disulfide bonds are predominantly generated by the two isoforms of Ero1 (ER oxidoreductin-1): Ero1α and Ero1β. The activity of Ero1α is tightly regulated through the formation of intramolecular disulfide bonds to help ensure balanced ER redox conditions. Ero1β is less tightly regulated, but the molecular details underlying control of activity are not as well characterized as for Ero1α. Ero1β contains an additional cysteine residue (Cys262), which has been suggested to engage in an isoform-specific regulatory disulfide bond with Cys100. However, we show that the two regulatory disulfide bonds in Ero1α are likely conserved in Ero1β (Cys90–Cys130 and Cys95–Cys100). Molecular modelling of the Ero1β structure predicted that the side chain of Cys262 is completely buried. Indeed, we found this cysteine to be reduced and partially protected from alkylation in the ER of living cells. Furthermore, mutation of Cys100–but not of Cys262–rendered Ero1β hyperactive in cells, as did mutation of Cys130. Ero1β hyperactivity induced the UPR (unfolded protein response) and resulted in oxidative perturbation of the ER redox state. We propose that features other than a distinct pattern of regulatory disulfide bonds determine the loose redox regulation of Ero1β relative to Ero1α. Our findings indicate that the regulatory disulfide bonds are conserved in the human oxidases Ero1α and Ero1β. We therefore propose that features other than a distinct pattern of disulfide bonds determine the previously established difference in regulation of Ero1α and Ero1β activity.
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34
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Missing links in antibody assembly control. Int J Cell Biol 2013; 2013:606703. [PMID: 24489546 PMCID: PMC3893805 DOI: 10.1155/2013/606703] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 10/07/2013] [Indexed: 12/21/2022] Open
Abstract
Fidelity of the humoral immune response requires that quiescent B lymphocytes display membrane bound immunoglobulin M (IgM) on B lymphocytes surface as part of the B cell receptor, whose function is to recognize an antigen. At the same time B lymphocytes should not secrete IgM until recognition of the antigen has occurred. The heavy chains of the secretory IgM have a C-terminal tail with a cysteine instead of a membrane anchor, which serves to covalently link the IgM subunits by disulfide bonds to form “pentamers” or “hexamers.” By virtue of the same cysteine, unassembled secretory IgM subunits are recognized and retained (via mixed disulfide bonds) by members of the protein disulfide isomerase family, in particular ERp44. This so-called “thiol-mediated retention” bars assembly intermediates from prematurely leaving the cell and thereby exerts quality control on the humoral immune response. In this essay we discuss recent findings on how ERp44 governs such assembly control in a pH-dependent manner, shuttling between the cisGolgi and endoplasmic reticulum, and finally on how pERp1/MZB1, possibly as a co-chaperone of GRP94, may help to overrule the thiol-mediated retention in the activated B cell to give way to antibody secretion.
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Montero D, Tachibana C, Rahr Winther J, Appenzeller-Herzog C. Intracellular glutathione pools are heterogeneously concentrated. Redox Biol 2013; 1:508-13. [PMID: 24251119 PMCID: PMC3830055 DOI: 10.1016/j.redox.2013.10.005] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 12/16/2022] Open
Abstract
Glutathione is present in millimolar concentrations in the cell, but its relative distribution among cellular compartments remains elusive. We have chosen the endoplasmic reticulum (ER) as an example organelle to study compartment-specific glutathione levels. Using a glutaredoxin sensor (sCGrx1pER), which rapidly and specifically equilibrates with the reduced glutathione (GSH)–glutathione disulfide (GSSG) redox couple with known equilibrium constant, we showed that the [GSH]:[GSSG] ratio in the ER of intact HeLa cells is less than 7:1. Taking into consideration the previously determined value for [GSH]2:[GSSG] in the ER of 83 mM, this translates into a total glutathione concentration in the ER ([GStot]=[GSH]+2[GSSG]) of greater than 15 mM. Since the integrated, intracellular [GStot] was measured as ~7 mM, we conclude the existence of a [GStot] gradient across the ER membrane. A possible homeostatic mechanism by which cytosol-derived glutathione is trapped in the ER is discussed. We propose a high [GStot] as a distinguishing feature of the ER environment compared to the extracellular space. Glutathionylation status of a 1-Cys glutaredoxin is a readout for [GSH]:[GSSG]. Compartment-specific [GStot] is given by [GSH]:[GSSG] and [GSH]2:[GSSG]. [GStot] is higher in the ER than in the cytosol of human cells.
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Key Words
- DTT, Dithiothreitol
- EGSH, Half cell reduction potential of glutathione
- ER, Endoplasmic reticulum
- Endoplasmic reticulum
- GSH, Reduced glutathione
- GSSG, Glutathione disulfide
- Glutaredoxin
- Glutathione
- NEM, N-ethylmaleimide
- OxD, Percentage of oxidation
- PDI, Protein disulfide isomerase
- PERK, Double stranded RNA-activated protein kinase (PKR)-like ER kinase
- RGS, [GSH]:[GSSG]
- Redox Homeostasis
- Redox compartmentalization
- Redox, Reduction–oxidation
- Reduction potential
- TMM(PEG)12, Maleimide-activated polyethylene glycol
- UPR, Unfolded protein response
- XBP1, X-box binding protein 1
- [GStot], Total glutathione concentration
- sCGrx1p, C30S mutant of yeast glutaredoxin 1
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Affiliation(s)
- Davide Montero
- Division of Molecular & Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
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Oxidative protein-folding systems in plant cells. Int J Cell Biol 2013; 2013:585431. [PMID: 24187554 PMCID: PMC3800646 DOI: 10.1155/2013/585431] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 08/01/2013] [Indexed: 12/13/2022] Open
Abstract
Plants are unique among eukaryotes in having evolved organelles: the protein storage vacuole, protein body, and chloroplast. Disulfide transfer pathways that function in the endoplasmic reticulum (ER) and chloroplasts of plants play critical roles in the development of protein storage organelles and the biogenesis of chloroplasts, respectively. Disulfide bond formation requires the cooperative function of disulfide-generating enzymes (e.g., ER oxidoreductase 1), which generate disulfide bonds de novo, and disulfide carrier proteins (e.g., protein disulfide isomerase), which transfer disulfides to substrates by means of thiol-disulfide exchange reactions. Selective molecular communication between disulfide-generating enzymes and disulfide carrier proteins, which reflects the molecular and structural diversity of disulfide carrier proteins, is key to the efficient transfer of disulfides to specific sets of substrates. This review focuses on recent advances in our understanding of the mechanisms and functions of the various disulfide transfer pathways involved in oxidative protein folding in the ER, chloroplasts, and mitochondria of plants.
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Kakihana T, Araki K, Vavassori S, Iemura SI, Cortini M, Fagioli C, Natsume T, Sitia R, Nagata K. Dynamic regulation of Ero1α and peroxiredoxin 4 localization in the secretory pathway. J Biol Chem 2013; 288:29586-94. [PMID: 23979138 PMCID: PMC3795256 DOI: 10.1074/jbc.m113.467845] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In the early secretory compartment (ESC), a network of chaperones and enzymes assists oxidative folding of nascent proteins. Ero1 flavoproteins oxidize protein disulfide isomerase (PDI), generating H2O2 as a byproduct. Peroxiredoxin 4 (Prx4) can utilize luminal H2O2 to oxidize PDI, thus favoring oxidative folding while limiting oxidative stress. Interestingly, neither ER oxidase contains known ER retention signal(s), raising the question of how cells prevent their secretion. Here we show that the two proteins share similar intracellular localization mechanisms. Their secretion is prevented by sequential interactions with PDI and ERp44, two resident proteins of the ESC-bearing KDEL-like motifs. PDI binds preferentially Ero1α, whereas ERp44 equally retains Ero1α and Prx4. The different binding properties of Ero1α and Prx4 increase the robustness of ER redox homeostasis.
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Affiliation(s)
- Taichi Kakihana
- From the Department of Molecular and Cellular Biology, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8397, Japan
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38
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Aller I, Meyer AJ. The oxidative protein folding machinery in plant cells. PROTOPLASMA 2013; 250:799-816. [PMID: 23090240 DOI: 10.1007/s00709-012-0463-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 10/02/2012] [Indexed: 06/01/2023]
Abstract
Formation of intra-molecular disulfides and concomitant oxidative protein folding is essential for stability and catalytic function of many soluble and membrane-bound proteins in the endomembrane system, the mitochondrial inter-membrane space and the thylakoid lumen. Disulfide generation from free cysteines in nascent polypeptide chains is generally a catalysed process for which distinct pathways exist in all compartments. A high degree of similarities between highly diverse eukaryotic and bacterial systems for generation of protein disulfides indicates functional conservation of key processes throughout evolution. However, while many aspects about molecular function of enzymatic systems promoting disulfide formation have been demonstrated for bacterial and non-plant eukaryotic organisms, it is now clear that the plant machinery for oxidative protein folding displays distinct details, suggesting that the different pathways have been adapted to plant-specific requirements in terms of compartmentation, molecular function and regulation. Here, we aim to evaluate biological diversity by comparing the plant systems for oxidative protein folding to the respective systems from non-plant eukaryotes.
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Affiliation(s)
- Isabel Aller
- INRES-Chemical Signalling, University of Bonn, Friedrich-Ebert-Allee 144, D-53113 Bonn, Germany
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39
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A pH-regulated quality control cycle for surveillance of secretory protein assembly. Mol Cell 2013; 50:783-92. [PMID: 23685074 PMCID: PMC3699783 DOI: 10.1016/j.molcel.2013.04.016] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 03/02/2013] [Accepted: 04/10/2013] [Indexed: 11/30/2022]
Abstract
To warrant the quality of the secretory proteome, stringent control systems operate at the endoplasmic reticulum (ER)-Golgi interface, preventing the release of nonnative products. Incompletely assembled oligomeric proteins that are deemed correctly folded must rely on additional quality control mechanisms dedicated to proper assembly. Here we unveil how ERp44 cycles between cisGolgi and ER in a pH-regulated manner, patrolling assembly of disulfide-linked oligomers such as IgM and adiponectin. At neutral, ER-equivalent pH, the ERp44 carboxy-terminal tail occludes the substrate-binding site. At the lower pH of the cisGolgi, conformational rearrangements of this peptide, likely involving protonation of ERp44’s active cysteine, simultaneously unmask the substrate binding site and −RDEL motif, allowing capture of orphan secretory protein subunits and ER retrieval via KDEL receptors. The ERp44 assembly control cycle couples secretion fidelity and efficiency downstream of the calnexin/calreticulin and BiP-dependent quality control cycles. ERp44 governs a pH-regulated assembly control cycle in the early secretory pathway Accessibility of ERp44’s active site and –RDEL ER retrieval motif is pH dependent Unmasking of ERp44’s active site likely involves protonation of cysteine 29 ERp44 captures client proteins at cisGolgi-equivalent pH for retrieval to the ER
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40
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Bubenik JL, Miniard AC, Driscoll DM. Alternative transcripts and 3'UTR elements govern the incorporation of selenocysteine into selenoprotein S. PLoS One 2013; 8:e62102. [PMID: 23614019 PMCID: PMC3628699 DOI: 10.1371/journal.pone.0062102] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 03/16/2013] [Indexed: 01/01/2023] Open
Abstract
Selenoprotein S (SelS) is a 189 amino acid trans-membrane protein that plays an important yet undefined role in the unfolded protein response. It has been proposed that SelS may function as a reductase, with the penultimate selenocysteine (Sec188) residue participating in a selenosulfide bond with cysteine (Cys174). Cotranslational incorporation of Sec into SelS depends on the recoding of the UGA codon, which requires a Selenocysteine Insertion Sequence (SECIS) element in the 3′UTR of the transcript. Here we identify multiple mechanisms that regulate the expression of SelS. The human SelS gene encodes two transcripts (variants 1 and 2), which differ in their 3′UTR sequences due to an alternative splicing event that removes the SECIS element from the variant 1 transcript. Both transcripts are widely expressed in human cell lines, with the SECIS-containing variant 2 mRNA being more abundant. In vitro experiments demonstrate that the variant 1 3′UTR does not allow readthrough of the UGA/Sec codon. Thus, this transcript would produce a truncated protein that does not contain Sec and cannot make the selenosulfide bond. While the variant 2 3′UTR does support Sec insertion, its activity is weak. Bioinformatic analysis revealed two highly conserved stem-loop structures, one in the proximal part of the variant 2 3′UTR and the other immediately downstream of the SECIS element. The proximal stem-loop promotes Sec insertion in the native context but not when positioned far from the UGA/Sec codon in a heterologous mRNA. In contrast, the 140 nucleotides downstream of the SECIS element inhibit Sec insertion. We also show that endogenous SelS is enriched at perinuclear speckles, in addition to its known localization in the endoplasmic reticulum. Our results suggest the expression of endogenous SelS is more complex than previously appreciated, which has implications for past and future studies on the function of this protein.
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Affiliation(s)
- Jodi L. Bubenik
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- * E-mail: (JLB); (DMD)
| | - Angela C. Miniard
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Donna M. Driscoll
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail: (JLB); (DMD)
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41
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Birk J, Meyer M, Aller I, Hansen HG, Odermatt A, Dick TP, Meyer AJ, Appenzeller-Herzog C. Endoplasmic reticulum: reduced and oxidized glutathione revisited. J Cell Sci 2013; 126:1604-17. [PMID: 23424194 DOI: 10.1242/jcs.117218] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The reducing power of glutathione, expressed by its reduction potential EGSH, is an accepted measure for redox conditions in a given cell compartment. In the endoplasmic reticulum (ER), EGSH is less reducing than elsewhere in the cell. However, attempts to determine EGSH(ER) have been inconsistent and based on ineligible assumptions. Using a codon-optimized and evidently glutathione-specific glutaredoxin-coupled redox-sensitive green fluorescent protein (roGFP) variant, we determined EGSH(ER) in HeLa cells as -208±4 mV (at pH 7.0). At variance with existing models, this is not oxidizing enough to maintain the known redox state of protein disulfide isomerase family enzymes. Live-cell microscopy confirmed ER hypo-oxidation upon inhibition of ER Ca(2+) import. Conversely, stressing the ER with a glycosylation inhibitor did not lead to more reducing conditions, as reported for yeast. These results, which for the first time establish the oxidative capacity of glutathione in the ER, illustrate a context-dependent interplay between ER stress and EGSH(ER). The reported development of ER-localized EGSH sensors will enable more targeted in vivo redox analyses in ER-related disorders.
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Affiliation(s)
- Julia Birk
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056 Basel, Switzerland
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42
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Groenendyk J, Agellon LB, Michalak M. Coping with endoplasmic reticulum stress in the cardiovascular system. Annu Rev Physiol 2012; 75:49-67. [PMID: 23020580 DOI: 10.1146/annurev-physiol-030212-183707] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The endoplasmic reticulum (ER) is a multifunctional intracellular organelle, a component of the cellular reticular network that allows cells to adjust to a wide variety of conditions. The cardiomyocyte reticular network is the ideal location of sensors for both intrinsic and extrinsic factors that disrupt energy and/or nutrient homeostasis and lead to ER stress, a disturbance in ER function. ER stress has been linked to both physiological and pathological states in the cardiovascular system; such states include myocardial infarction, oxygen starvation (hypoxia) and fuel starvation, ischemia, pressure overload, dilated cardiomyopathy, hypertrophy, and heart failure. The ER stress coping response (e.g., the unfolded protein response) is composed of discrete pathways that are controlled by a collection of common regulatory components that may function as a single entity involved in reacting to ER stress. These corrective strategies allow the cardiomyocyte reticular network to restore energy and/or nutrient homeostasis and to avoid cell death. Therefore, the identities of the ER stress corrective strategies are important targets for the development of therapeutic approaches for cardiovascular and other acquired disorders.
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Affiliation(s)
- Jody Groenendyk
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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43
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Haque SJ, Majumdar T, Barik S. Redox-assisted protein folding systems in eukaryotic parasites. Antioxid Redox Signal 2012; 17:674-83. [PMID: 22122448 PMCID: PMC3373220 DOI: 10.1089/ars.2011.4433] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SIGNIFICANCE The cysteine (Cys) residues of proteins play two fundamentally important roles. They serve as sites of post-translational redox modifications as well as influence the conformation of the protein through the formation of disulfide bonds. RECENT ADVANCES Redox-related and redox-associated protein folding in protozoan parasites has been found to be a major mode of regulation, affecting myriad aspects of the parasitic life cycle, host-parasite interactions, and the disease pathology. Available genome sequences of various parasites have begun to complement the classical biochemical and enzymological studies of these processes. In this article, we summarize the reversible Cys disulfide (S-S) bond formation in various classes of strategically important parasitic proteins, and its structural consequence and functional relevance. CRITICAL ISSUES Molecular mechanisms of folding remain under-studied and often disconnected from functional relevance. FUTURE DIRECTIONS The clinical benefit of redox research will require a comprehensive characterization of the various isoforms and paralogs of the redox enzymes and their concerted effect on the structure and function of the specific parasitic client proteins.
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Affiliation(s)
- Saikh Jaharul Haque
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
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44
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Jansen G, Määttänen P, Denisov AY, Scarffe L, Schade B, Balghi H, Dejgaard K, Chen LY, Muller WJ, Gehring K, Thomas DY. An interaction map of endoplasmic reticulum chaperones and foldases. Mol Cell Proteomics 2012; 11:710-23. [PMID: 22665516 DOI: 10.1074/mcp.m111.016550] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Chaperones and foldases in the endoplasmic reticulum (ER) ensure correct protein folding. Extensive protein-protein interaction maps have defined the organization and function of many cellular complexes, but ER complexes are under-represented. Consequently, chaperone and foldase networks in the ER are largely uncharacterized. Using complementary ER-specific methods, we have mapped interactions between ER-lumenal chaperones and foldases and describe their organization in multiprotein complexes. We identify new functional chaperone modules, including interactions between protein-disulfide isomerases and peptidyl-prolyl cis-trans-isomerases. We have examined in detail a novel ERp72-cyclophilin B complex that enhances the rate of folding of immunoglobulin G. Deletion analysis and NMR reveal a conserved surface of cyclophilin B that interacts with polyacidic stretches of ERp72 and GRp94. Mutagenesis within this highly charged surface region abrogates interactions with its chaperone partners and reveals a new mechanism of ER protein-protein interaction. This ability of cyclophilin B to interact with different partners using the same molecular surface suggests that ER-chaperone/foldase partnerships may switch depending on the needs of different substrates, illustrating the flexibility of multichaperone complexes of the ER folding machinery.
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Affiliation(s)
- Gregor Jansen
- Department of Biochemistry, McGill University, Montréal, Québec H3G 1Y6, Canada
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45
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Ferreiro E, Baldeiras I, Ferreira IL, Costa RO, Rego AC, Pereira CF, Oliveira CR. Mitochondrial- and endoplasmic reticulum-associated oxidative stress in Alzheimer's disease: from pathogenesis to biomarkers. Int J Cell Biol 2012; 2012:735206. [PMID: 22701485 PMCID: PMC3373122 DOI: 10.1155/2012/735206] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 04/06/2012] [Indexed: 12/23/2022] Open
Abstract
Alzheimer's disease (AD) is the most common cause of dementia in the elderly, affecting several million of people worldwide. Pathological changes in the AD brain include the presence of amyloid plaques, neurofibrillary tangles, loss of neurons and synapses, and oxidative damage. These changes strongly associate with mitochondrial dysfunction and stress of the endoplasmic reticulum (ER). Mitochondrial dysfunction is intimately linked to the production of reactive oxygen species (ROS) and mitochondrial-driven apoptosis, which appear to be aggravated in the brain of AD patients. Concomitantly, mitochondria are closely associated with ER, and the deleterious crosstalk between both organelles has been shown to be involved in neuronal degeneration in AD. Stimuli that enhance expression of normal and/or folding-defective proteins activate an adaptive unfolded protein response (UPR) that, if unresolved, can cause apoptotic cell death. ER stress also induces the generation of ROS that, together with mitochondrial ROS and decreased activity of several antioxidant defenses, promotes chronic oxidative stress. In this paper we discuss the critical role of mitochondrial and ER dysfunction in oxidative injury in AD cellular and animal models, as well as in biological fluids from AD patients. Progress in developing peripheral and cerebrospinal fluid biomarkers related to oxidative stress will also be summarized.
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Affiliation(s)
- E. Ferreiro
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Largo Marquês de Pombal 3004-517, Coimbra, Portugal
| | - I. Baldeiras
- Faculty of Medicine, University of Coimbra, Rua Larga 3004-504, Coimbra, Portugal
- University Coimbra Hospital, 3000-075, Coimbra, Portugal
| | - I. L. Ferreira
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Largo Marquês de Pombal 3004-517, Coimbra, Portugal
| | - R. O. Costa
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Largo Marquês de Pombal 3004-517, Coimbra, Portugal
| | - A. C. Rego
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Largo Marquês de Pombal 3004-517, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Rua Larga 3004-504, Coimbra, Portugal
| | - C. F. Pereira
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Largo Marquês de Pombal 3004-517, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Rua Larga 3004-504, Coimbra, Portugal
| | - C. R. Oliveira
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Largo Marquês de Pombal 3004-517, Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Rua Larga 3004-504, Coimbra, Portugal
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Anelli T, Bergamelli L, Margittai E, Rimessi A, Fagioli C, Malgaroli A, Pinton P, Ripamonti M, Rizzuto R, Sitia R. Ero1α regulates Ca(2+) fluxes at the endoplasmic reticulum-mitochondria interface (MAM). Antioxid Redox Signal 2012; 16:1077-87. [PMID: 21854214 DOI: 10.1089/ars.2011.4004] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
AIMS The endoplasmic reticulum (ER) is involved in many functions, including protein folding, redox homeostasis, and Ca(2+) storage and signaling. To perform these multiple tasks, the ER is composed of distinct, specialized subregions, amongst which mitochondrial-associated ER membranes (MAM) emerge as key signaling hubs. How these multiple functions are integrated with one another in living cells remains unclear. RESULTS Here we show that Ero1α, a key controller of oxidative folding and ER redox homeostasis, is enriched in MAM and regulates Ca(2+) fluxes. Downregulation of Ero1α by RNA interference inhibits mitochondrial Ca(2+) fluxes and modifies the activity of mitochondrial Ca(2+) uniporters. The overexpression of redox active Ero1α increases passive Ca(2+) efflux from the ER, lowering [Ca(2+)](ER) and mitochondrial Ca(2+) fluxes in response to IP3 agonists. INNOVATION The unexpected observation that Ca(2+) fluxes are affected by either increasing or decreasing the levels of Ero1α reveals a pivotal role for this oxidase in the early secretory compartment and implies a strict control of its amounts. CONCLUSIONS Taken together, our results indicate that the levels, subcellular localization, and activity of Ero1α coordinately regulate Ca(2+) and redox homeostasis and signaling in the early secretory compartment.
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47
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Ramming T, Appenzeller-Herzog C. The physiological functions of mammalian endoplasmic oxidoreductin 1: on disulfides and more. Antioxid Redox Signal 2012; 16:1109-18. [PMID: 22220984 DOI: 10.1089/ars.2011.4475] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
SIGNIFICANCE The oxidative process of disulfide-bond formation is essential for the folding of most secretory and membrane proteins in the endoplasmic reticulum (ER). It is driven by electron relay pathways that transfer two electrons derived from the fusion of two adjacent cysteinyl side chains onto various types of chemical oxidants. The conserved, ER-resident endoplasmic oxidoreductin 1 (Ero1) sulfhydryl oxidases that reduce molecular oxygen to generate an active-site disulfide represent one of these pathways. In mammals, two family members exist, Ero1α and Ero1β. RECENT ADVANCES The two mammalian Ero1 enzymes differ in transcriptional and post-translational regulation, tissue distribution, and catalytic turnover. A specific protein-protein interaction between either isoform and protein disulfide isomerase (PDI) facilitates the propagation of disulfides from Ero1 via PDI to nascent polypeptides, and inbuilt oxidative shutdown mechanisms in Ero1α and Ero1β prevent excessive oxidation of PDI. CRITICAL ISSUES Besides disulfide-bond generation, Ero1α also regulates calcium release from the ER and the secretion of disulfide-linked oligomers through its reversible association with the chaperone ERp44. This review explores the functional repertoire and possible redundancy of mammalian Ero1 enzymes. FUTURE DIRECTIONS Systematic analyses of different knockout mouse models will be the most promising strategy to shed new light on unique and tissue-specific roles of Ero1α and Ero1β. Moreover, in-depth characterization of the known physical interactions of Ero1 with peroxidases and PDI family members will help broaden our functional and mechanistic understanding of Ero1 enzymes.
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Affiliation(s)
- Thomas Ramming
- Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, University of Basel, Switzerland
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48
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Kakihana T, Nagata K, Sitia R. Peroxides and peroxidases in the endoplasmic reticulum: integrating redox homeostasis and oxidative folding. Antioxid Redox Signal 2012; 16:763-71. [PMID: 22146055 DOI: 10.1089/ars.2011.4238] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
SIGNIFICANCE The endoplasmic reticulum (ER), the port of entry into the secretory pathway, is a complex organelle that performs many fundamental functions, including protein synthesis and quality control, Ca(2+) storage and signaling. Redox homeostasis is of paramount importance for allowing the efficient folding of secretory proteins, most of which contain essential disulfide bonds. RECENT ADVANCES revealed that an intricate protein network sustains the processes of disulfide bond formation and reshuffling in the ER. Remarkably, H(2)O(2), which is a known by-product of Ero1 flavoproteins in cells, is utilized by peroxiredoxin-4 and glutathione peroxidases-7 and -8, which reside in the mammalian secretory compartment and further fuel oxidative protein folding while limiting oxidative damage. CRITICAL ISSUES that remain to be addressed are the sources, diffusibility and signaling role(s) of H(2)O(2) in and between organelles and cells, how the emerging redundancy in the systems is coupled to precise regulation, and how the distinct pathways operating in the early secretory compartment are integrated with one another. FUTURE DIRECTIONS A further dissection of the pathways that integrate folding, redox homeostasis, and signaling in the early secretory pathway may allow to manipulate protein homeostasis and survival-death decisions in degenerative diseases or cancer.
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Affiliation(s)
- Taichi Kakihana
- Department of Molecular and Cellular Biology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
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49
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Krügel U, He HX, Gier K, Reins J, Chincinska I, Grimm B, Schulze WX, Kühn C. The potato sucrose transporter StSUT1 interacts with a DRM-associated protein disulfide isomerase. MOLECULAR PLANT 2012; 5:43-62. [PMID: 21746698 DOI: 10.1093/mp/ssr048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Organization of proteins into complexes is crucial for many cellular functions. Recently, the SUT1 protein was shown to form homodimeric complexes, to be associated with lipid raft-like microdomains in yeast as well as in plants and to undergo endocytosis in response to brefeldin A. We therefore aimed to identify SUT1-interacting proteins that might be involved in dimerization, endocytosis, or targeting of SUT1 to raft-like microdomains. Therefore, we identified potato membrane proteins, which are associated with the detergent-resistant membrane (DRM) fraction. Among the proteins identified, we clearly confirmed StSUT1 as part of DRM in potato source leaves. We used the yeast two-hybrid split ubiquitin system (SUS) to systematically screen for interaction between the sucrose transporter StSUT1 and other membrane-associated or soluble proteins in vivo. The SUS screen was followed by immunoprecipitation using affinity-purified StSUT1-specific peptide antibodies and mass spectrometric analysis of co-precipitated proteins. A large overlap was observed between the StSUT1-interacting proteins identified in the co-immunoprecipitation and the detergent-resistant membrane fraction. One of the SUT1-interacting proteins, a protein disulfide isomerase (PDI), interacts also with other sucrose transporter proteins. A potential role of the PDI as escort protein is discussed.
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Affiliation(s)
- Undine Krügel
- Institute of Biology, Department of Plant Physiology, Humboldt University, 10115 Berlin, Germany
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ERp44 C160S/C212S mutants regulate IP3R1 channel activity. Protein Cell 2011; 2:990-6. [PMID: 22183808 DOI: 10.1007/s13238-011-1116-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 10/20/2011] [Indexed: 10/14/2022] Open
Abstract
Previous studies have indicated that ERp44 inhibits inositol 1,4,5-trisphosphate (IP(3))-induced Ca(2+) release (IICR) via IP(3)R(1), but the mechanism remains largely unexplored. Using extracellular ATP to induce intracellular calcium transient as an IICR model, Ca(2+) image, pull down assay, and Western blotting experiments were carried out in the present study. We found that extracellular ATP induced calcium transient via IP(3)Rs (IICR) and the IICR were markedly decreased in ERp44 overexpressed Hela cells. The inhibitory effect of C160S/C212S but not C29S/T396A/ΔT(331-377) mutants of ERp44 on IICR were significantly decreased compared with ERp44. However, the binding capacity of ERp44 to L3V domain of IP(3)R(1) (1L3V) was enhanced by ERp44 C160S/C212S mutation. Taken together, these results suggest that the mutants of ERp44, C160/C212, can more tightly bind to IP(3)R(1) but exhibit a weak inhibition of IP(3)R(1) channel activity in Hela cells.
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