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Adhikari B, Gayral M, Herath V, Bedsole CO, Kumar S, Ball H, Atallah O, Shaw B, Pajerowska-Mukhtar KM, Verchot J. bZIP60 and Bax inhibitor 1 contribute IRE1-dependent and independent roles to potexvirus infection. THE NEW PHYTOLOGIST 2024; 243:1172-1189. [PMID: 38853429 DOI: 10.1111/nph.19882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 05/14/2024] [Indexed: 06/11/2024]
Abstract
IRE1, BI-1, and bZIP60 monitor compatible plant-potexvirus interactions though recognition of the viral TGB3 protein. This study was undertaken to elucidate the roles of three IRE1 isoforms, the bZIP60U and bZIP60S, and BI-1 roles in genetic reprogramming of cells during potexvirus infection. Experiments were performed using Arabidopsis thaliana knockout lines and Plantago asiatica mosaic virus infectious clone tagged with the green fluorescent protein gene (PlAMV-GFP). There were more PlAMV-GFP infection foci in ire1a/b, ire1c, bzip60, and bi-1 knockout than wild-type (WT) plants. Cell-to-cell movement and systemic RNA levels were greater bzip60 and bi-1 than in WT plants. Overall, these data indicate an increased susceptibility to virus infection. Transgenic overexpression of AtIRE1b or StbZIP60 in ire1a/b or bzip60 mutant background reduced virus infection foci, while StbZIP60 expression influences virus movement. Transgenic overexpression of StbZIP60 also confers endoplasmic reticulum (ER) stress resistance following tunicamycin treatment. We also show bZIP60U and TGB3 interact at the ER. This is the first demonstration of a potato bZIP transcription factor complementing genetic defects in Arabidopsis. Evidence indicates that the three IRE1 isoforms regulate the initial stages of virus replication and gene expression, while bZIP60 and BI-1 contribute separately to virus cell-to-cell and systemic movement.
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Affiliation(s)
- Binita Adhikari
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | - Mathieu Gayral
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
- Agroécologie, INRAE, Institut Agro Dijon, Université de Bourgogne, 26, bd Docteur Petitjean-BP 87999, Dijon, Cedex, 21079, France
| | - Venura Herath
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
- Department of Agricultural Biology, Faculty of Agriculture, University of Peradeniya, Peradeniya, 20400, Sri Lanka
| | - Caleb Oliver Bedsole
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | - Sandeep Kumar
- Department of Plant Pathology, College of Agriculture, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, 751003, India
| | - Haden Ball
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | - Osama Atallah
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | - Brian Shaw
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
| | | | - Jeanmarie Verchot
- Department of Plant Pathology and Microbiology, Texas A&M University, 496 Olsen Blvd, College Station, TX, 77845, USA
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2
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Das A, Cheng H, Wang Y, Kinch LN, Liang G, Hong S, Hobbs HH, Cohen JC. The ubiquitin E3 ligase BFAR promotes degradation of PNPLA3. Proc Natl Acad Sci U S A 2024; 121:e2312291121. [PMID: 38294943 PMCID: PMC10861911 DOI: 10.1073/pnas.2312291121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 12/26/2023] [Indexed: 02/02/2024] Open
Abstract
A missense variant in patatin-like phospholipase domain-containing protein 3 [PNPLA3(I148M)] is the most impactful genetic risk factor for fatty liver disease (FLD). We previously showed that PNPLA3 is ubiquitylated and subsequently degraded by proteasomes and autophagosomes and that the PNPLA3(148M) variant interferes with this process. To define the machinery responsible for PNPLA3 turnover, we used small interfering (si)RNAs to inactivate components of the ubiquitin proteasome system. Inactivation of bifunctional apoptosis regulator (BFAR), a membrane-bound E3 ubiquitin ligase, reproducibly increased PNPLA3 levels in two lines of cultured hepatocytes. Conversely, overexpression of BFAR decreased levels of endogenous PNPLA3 in HuH7 cells. BFAR and PNPLA3 co-immunoprecipitated when co-expressed in cells. BFAR promoted ubiquitylation of PNPLA3 in vitro in a reconstitution assay using purified, epitope-tagged recombinant proteins. To confirm that BFAR targets PNPLA3, we inactivated Bfar in mice. Levels of PNPLA3 protein were increased twofold in hepatic lipid droplets of Bfar-/- mice with no associated increase in PNPLA3 mRNA levels. Taken together these data are consistent with a model in which BFAR plays a role in the post-translational degradation of PNPLA3. The identification of BFAR provides a potential target to enhance PNPLA3 turnover and prevent FLD.
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Affiliation(s)
- Avash Das
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Haili Cheng
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Yang Wang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Lisa N. Kinch
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Guosheng Liang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Sen Hong
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Helen H. Hobbs
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX75390
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Jonathan C. Cohen
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX75390
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX75390
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3
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Christianson JC, Jarosch E, Sommer T. Mechanisms of substrate processing during ER-associated protein degradation. Nat Rev Mol Cell Biol 2023; 24:777-796. [PMID: 37528230 DOI: 10.1038/s41580-023-00633-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2023] [Indexed: 08/03/2023]
Abstract
Maintaining proteome integrity is essential for long-term viability of all organisms and is overseen by intrinsic quality control mechanisms. The secretory pathway of eukaryotes poses a challenge for such quality assurance as proteins destined for secretion enter the endoplasmic reticulum (ER) and become spatially segregated from the cytosolic machinery responsible for disposal of aberrant (misfolded or otherwise damaged) or superfluous polypeptides. The elegant solution provided by evolution is ER-membrane-bound ubiquitylation machinery that recognizes misfolded or surplus proteins or by-products of protein biosynthesis in the ER and delivers them to 26S proteasomes for degradation. ER-associated protein degradation (ERAD) collectively describes this specialized arm of protein quality control via the ubiquitin-proteasome system. But, instead of providing a single strategy to remove defective or unwanted proteins, ERAD represents a collection of independent processes that exhibit distinct yet overlapping selectivity for a wide range of substrates. Not surprisingly, ER-membrane-embedded ubiquitin ligases (ER-E3s) act as central hubs for each of these separate ERAD disposal routes. In these processes, ER-E3s cooperate with a plethora of specialized factors, coordinating recognition, transport and ubiquitylation of undesirable secretory, membrane and cytoplasmic proteins. In this Review, we focus on substrate processing during ERAD, highlighting common threads as well as differences between the many routes via ERAD.
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Affiliation(s)
- John C Christianson
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK.
| | - Ernst Jarosch
- Max-Delbrück-Centrer for Molecular Medicine in Helmholtz Association, Berlin-Buch, Germany
| | - Thomas Sommer
- Max-Delbrück-Centrer for Molecular Medicine in Helmholtz Association, Berlin-Buch, Germany.
- Institute for Biology, Humboldt Universität zu Berlin, Berlin, Germany.
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4
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Xie H, Shi Y, Zhou Y, Liu H. TMBIM6 promotes diabetic tubular epithelial cell survival and albumin endocytosis by inhibiting the endoplasmic reticulum stress sensor, IRE1α. Mol Biol Rep 2022; 49:9181-9194. [PMID: 35857174 DOI: 10.1007/s11033-022-07744-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 11/25/2022]
Abstract
AIM Reduced albumin reabsorption in proximal tubular epithelial cells (PTECs), resulting from decreased megalin plasma membrane (PM) localization due to prolonged endoplasmic reticulum (ER) stress, potentially contributes to albuminuria in early diabetic kidney disease (DKD). To examine this possibility, we investigated the cytoprotective effect of TMBIM6 in promoting diabetic PTEC survival and albumin endocytosis by attenuating ER stress with an IRE1α inhibitor, KIRA6. METHODS AND RESULTS Renal TMBIM6 distribution and expression were determined by immunohistochemistry, western blotting, and qPCR, whereas tubular injury was evaluated in db/db mice. High-glucose (HG)-treated HK-2 cells were either treated with KIRA6 or transduced with a lentiviral vector for TMBIM6 overexpression. ER stress was measured by western blotting and ER-Tracker Red staining, whereas apoptosis was determined by performing TUNEL assays. Megalin expression was measured by immunofluorescence, and albumin endocytosis was evaluated after incubating cells with FITC-labeled albumin. Tubular injury and TMBIM6 downregulation occurred in db/db mouse renal cortical tissues. Both KIRA6 treatment and TMBIM6 overexpression inhibited ER stress by decreasing the levels of phosphorylated IRE1α, XBP1s, GRP78, and CHOP, and stabilizing ER expansion in HG-treated HK-2 cells. TUNEL assays performed with KIRA6-treated or TMBIM6-overexpressing cells showed a significant decrease in apoptosis, consistent with the significant downregulation of BAX and upregulation of BCL-2, as measured by immunoblotting. Both KIRA6 and TMBIM6 overexpression promoted megalin PM localization and restored albumin endocytosis in HG-treated HK-2 cells. CONCLUSION TMBIM6 promoted diabetic PTEC survival and albumin endocytosis by negatively regulating the IRE1α branch of ER stress.
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Affiliation(s)
- Huidi Xie
- Department of Nephrology and Endocrinology (A), Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Yang Shi
- Department of Nephrology and Endocrinology (A), Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Ying Zhou
- Department of Nephrology and Endocrinology (A), Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Hongfang Liu
- Department of Nephrology and Endocrinology (A), Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing, China.
- Dongzhimen Hospital, Renal Research Institute of Beijing University of Chinese Medicine, Beijing University of Chinese Medicine, No. 5, Haiyuncang Alley, Dongcheng District, 100700, Beijing, China.
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5
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Quistgaard EM. BAP31: Physiological functions and roles in disease. Biochimie 2021; 186:105-129. [PMID: 33930507 DOI: 10.1016/j.biochi.2021.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/22/2022]
Abstract
B-cell receptor-associated protein 31 (BAP31 or BCAP31) is a ubiquitously expressed transmembrane protein found mainly in the endoplasmic reticulum (ER), including in mitochondria-associated membranes (MAMs). It acts as a broad-specificity membrane protein chaperone and quality control factor, which can promote different fates for its clients, including ER retention, ER export, ER-associated degradation (ERAD), or evasion of degradation, and it also acts as a MAM tetherer and regulatory protein. It is involved in several cellular processes - it supports ER and mitochondrial homeostasis, promotes proliferation and migration, plays several roles in metabolism and the immune system, and regulates autophagy and apoptosis. Full-length BAP31 can be anti-apoptotic, but can also mediate activation of caspase-8, and itself be cleaved by caspase-8 into p20-BAP31, which promotes apoptosis by mobilizing ER calcium stores at MAMs. BAP31 loss-of-function mutations is the cause of 'deafness, dystonia, and central hypomyelination' (DDCH) syndrome, characterized by severe neurological symptoms and early death. BAP31 is furthermore implicated in a growing number of cancers and other diseases, and several viruses have been found to target it to promote their survival or life cycle progression. The purpose of this review is to provide an overview and examination of the basic properties, functions, mechanisms, and roles in disease of BAP31.
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Affiliation(s)
- Esben M Quistgaard
- Department of Molecular Biology and Genetics - DANDRITE, Aarhus University, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark.
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6
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Qu J, Zou T, Lin Z. The Roles of the Ubiquitin-Proteasome System in the Endoplasmic Reticulum Stress Pathway. Int J Mol Sci 2021; 22:1526. [PMID: 33546413 PMCID: PMC7913544 DOI: 10.3390/ijms22041526] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 02/07/2023] Open
Abstract
The endoplasmic reticulum (ER) is a highly dynamic organelle in eukaryotic cells, which is essential for synthesis, processing, sorting of protein and lipid metabolism. However, the cells activate a defense mechanism called endoplasmic reticulum stress (ER stress) response and initiate unfolded protein response (UPR) as the unfolded proteins exceed the folding capacity of the ER due to the environmental influences or increased protein synthesis. ER stress can mediate many cellular processes, including autophagy, apoptosis and senescence. The ubiquitin-proteasome system (UPS) is involved in the degradation of more than 80% of proteins in the cells. Today, increasing numbers of studies have shown that the two important components of UPS, E3 ubiquitin ligases and deubiquitinases (DUBs), are tightly related to ER stress. In this review, we summarized the regulation of the E3 ubiquitin ligases and DUBs in ER stress.
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Affiliation(s)
| | | | - Zhenghong Lin
- School of Life Sciences, Chongqing University, Chongqing 401331, China; (J.Q.); (T.Z.)
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7
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Ma RH, Ni ZJ, Thakur K, Zhang F, Zhang YY, Zhang JG, Wei ZJ. Natural Compounds Play Therapeutic Roles in Various Human Pathologies via Regulating Endoplasmic Reticulum Pathway. MEDICINE IN DRUG DISCOVERY 2020. [DOI: 10.1016/j.medidd.2020.100065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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8
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Lebeaupin C, Blanc M, Vallée D, Keller H, Bailly-Maitre B. BAX inhibitor-1: between stress and survival. FEBS J 2020; 287:1722-1736. [PMID: 31841271 DOI: 10.1111/febs.15179] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/18/2019] [Accepted: 12/13/2019] [Indexed: 12/13/2022]
Abstract
Cellular gatekeepers are essential to maintain order within a cell and anticipate signals of stress to promote survival. BCL2 associated X, apoptosis regulator (BAX) inhibitor-1 (BI-1), also named transmembrane BAX inhibitor motif containing-6, is a highly conserved endoplasmic reticulum (ER) transmembrane protein. Originally identified as an inhibitor of BAX-induced apoptosis, its pro-survival properties have been expanded to include functions targeted against ER stress, calcium imbalance, reactive oxygen species accumulation, and metabolic dysregulation. Nevertheless, the structural biology and biochemical mechanism of action of BI-1 are still under debate. BI-1 has been implicated in several diseases, including chronic liver disease, diabetes, ischemia/reperfusion injury, neurodegeneration, and cancer. While most studies have demonstrated a beneficial role for BI-1 in the ubiquitous maintenance of cellular homeostasis, its expression in cancer cells seems most often to contribute to tumorigenesis and metastasis. Here, we summarize what is known about BI-1 and encourage future studies on BI-1's contribution to cellular life and death decisions to advocate its potential as a target for drug development and other therapeutic strategies.
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Affiliation(s)
- Cynthia Lebeaupin
- INSERM U1065, C3M, Université Côte d'Azur, Nice, France.,Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.,Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Marina Blanc
- INSERM U1065, C3M, Université Côte d'Azur, Nice, France
| | | | - Harald Keller
- INRA1355-CNRS7254, Université Côte d'Azur, Sophia Antipolis, France
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9
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Sharma A, Trivedi AK. Regulation of apoptosis by E3 ubiquitin ligases in ubiquitin proteasome system. Cell Biol Int 2019; 44:721-734. [PMID: 31814188 DOI: 10.1002/cbin.11277] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 12/06/2019] [Indexed: 11/10/2022]
Abstract
Apoptosis is an organised ATP-dependent programmed cell death that organisms have evolved to maintain homoeostatic cell numbers and eliminate unnecessary or unhealthy cells from the system. Dysregulation of apoptosis can have serious manifestations culminating into various diseases, especially cancer. Accurate control of apoptosis requires regulation of a wide range of growth enhancing as well as anti-oncogenic factors. Appropriate regulation of magnitude and temporal expression of key proteins is vital to maintain functional apoptotic signalling. Controlled protein turnover is thus critical to the unhindered operation of the apoptotic machinery, disruption of which can have severe consequences, foremost being oncogenic transformation of cells. The ubiquitin proteasome system (UPS) is one such major cellular pathway that maintains homoeostatic protein levels. Recent studies have found interesting links between these two fundamental cellular processes, wherein UPS depending on the cue can either inhibit or promote apoptosis. A diverse range of E3 ligases are involved in regulating the turnover of key proteins of the apoptotic pathway. This review summarises an overview of key E3 ubiquitin ligases involved in the regulation of the fundamental proteins involved in apoptosis, linking UPS to apoptosis and attempts to emphasize the significance of this relationship in context of cancer.
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Affiliation(s)
- Akshay Sharma
- LSS008, Division of Cancer Biology, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, 226031, India
| | - Arun K Trivedi
- LSS008, Division of Cancer Biology, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, 226031, India
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10
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Doycheva D, Xu N, Kaur H, Malaguit J, McBride DW, Tang J, Zhang JH. Adenoviral TMBIM6 vector attenuates ER-stress-induced apoptosis in a neonatal hypoxic-ischemic rat model. Dis Model Mech 2019; 12:dmm040352. [PMID: 31636086 PMCID: PMC6898997 DOI: 10.1242/dmm.040352] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 10/14/2019] [Indexed: 12/31/2022] Open
Abstract
Endoplasmic reticulum (ER) stress is a major pathology encountered after hypoxic-ischemic (HI) injury. Accumulation of unfolded proteins triggers the unfolded protein response (UPR), resulting in the activation of pro-apoptotic cascades that lead to cell death. Here, we identified Bax inhibitor 1 (BI-1), an evolutionarily conserved protein encoded by the transmembrane BAX inhibitor motif-containing 6 (TMBIM6) gene, as a novel modulator of ER-stress-induced apoptosis after HI brain injury in a neonatal rat pup. The main objective of our study was to overexpress BI-1, via viral-mediated gene delivery of human adenoviral-TMBIM6 (Ad-TMBIM6) vector, to investigate its anti-apoptotic effects as well as to elucidate its signaling pathways in an in vivo neonatal HI rat model and in vitro oxygen-glucose deprivation (OGD) model. Ten-day-old unsexed Sprague Dawley rat pups underwent right common carotid artery ligation followed by 1.5 h of hypoxia. Rat pups injected with Ad-TMBIM6 vector, 48 h pre-HI, showed a reduction in relative infarcted area size, attenuated neuronal degeneration and improved long-term neurological outcomes. Furthermore, silencing of BI-1 or further activating the IRE1α branch of the UPR, using a CRISPR activation plasmid, was shown to reverse the protective effects of BI-1. Based on our in vivo and in vitro data, the protective effects of BI-1 are mediated via inhibition of IRE1α signaling and in part via inhibition of the second stress sensor receptor, PERK. Overall, this study showed a novel role for BI-1 and ER stress in the pathophysiology of HI and could provide a basis for BI-1 as a potential therapeutic target.
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Affiliation(s)
- Desislava Doycheva
- Center for Neuroscience Research, Department of Physiology and Pharmacology, Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
| | - Ningbo Xu
- Center for Neuroscience Research, Department of Physiology and Pharmacology, Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
- Department of Interventional Radiology, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Harpreet Kaur
- Center for Neuroscience Research, Department of Physiology and Pharmacology, Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
| | - Jay Malaguit
- Center for Neuroscience Research, Department of Physiology and Pharmacology, Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
| | - Devin William McBride
- The Vivian L. Smith Department of Neurosurgery, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Jiping Tang
- Center for Neuroscience Research, Department of Physiology and Pharmacology, Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
| | - John H Zhang
- Center for Neuroscience Research, Department of Physiology and Pharmacology, Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
- Departments of Anesthesiology, Neurosurgery and Neurology, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
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11
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Nam SM, Jeon YJ. Proteostasis In The Endoplasmic Reticulum: Road to Cure. Cancers (Basel) 2019; 11:E1793. [PMID: 31739582 PMCID: PMC6895847 DOI: 10.3390/cancers11111793] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/04/2019] [Accepted: 11/12/2019] [Indexed: 12/14/2022] Open
Abstract
The endoplasmic reticulum (ER) is an interconnected organelle that is responsible for the biosynthesis, folding, maturation, stabilization, and trafficking of transmembrane and secretory proteins. Therefore, cells evolve protein quality-control equipment of the ER to ensure protein homeostasis, also termed proteostasis. However, disruption in the folding capacity of the ER caused by a large variety of pathophysiological insults leads to the accumulation of unfolded or misfolded proteins in this organelle, known as ER stress. Upon ER stress, unfolded protein response (UPR) of the ER is activated, integrates ER stress signals, and transduces the integrated signals to relive ER stress, thereby leading to the re-establishment of proteostasis. Intriguingly, severe and persistent ER stress and the subsequently sustained unfolded protein response (UPR) are closely associated with tumor development, angiogenesis, aggressiveness, immunosuppression, and therapeutic response of cancer. Additionally, the UPR interconnects various processes in and around the tumor microenvironment. Therefore, it has begun to be delineated that pharmacologically and genetically manipulating strategies directed to target the UPR of the ER might exhibit positive clinical outcome in cancer. In the present review, we summarize recent advances in our understanding of the UPR of the ER and the UPR of the ER-mitochondria interconnection. We also highlight new insights into how the UPR of the ER in response to pathophysiological perturbations is implicated in the pathogenesis of cancer. We provide the concept to target the UPR of the ER, eventually discussing the potential of therapeutic interventions for targeting the UPR of the ER for cancer treatment.
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Affiliation(s)
- Su Min Nam
- Department of Biochemistry, Chungnam National University College of Medicine, Daejeon 35015, Korea;
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon 35015, Korea
| | - Young Joo Jeon
- Department of Biochemistry, Chungnam National University College of Medicine, Daejeon 35015, Korea;
- Department of Medical Science, Chungnam National University College of Medicine, Daejeon 35015, Korea
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12
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Boddicker RL, Koltes JE, Fritz‐Waters ER, Koesterke L, Weeks N, Yin T, Mani V, Nettleton D, Reecy JM, Baumgard LH, Spencer JD, Gabler NK, Ross JW. Genome‐wide methylation profile following prenatal and postnatal dietary omega‐3 fatty acid supplementation in pigs. Anim Genet 2016; 47:658-671. [DOI: 10.1111/age.12468] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2016] [Indexed: 02/06/2023]
Affiliation(s)
- R. L. Boddicker
- Department of Animal Science Iowa State University Ames IA 50011 USA
| | - J. E. Koltes
- Department of Animal Science Iowa State University Ames IA 50011 USA
| | | | - L. Koesterke
- Texas Advanced Computing Center University of Texas Austin TX 78758‐4497 USA
| | - N. Weeks
- Department of Mathematics Iowa State University Ames IA 50011 USA
| | - T. Yin
- Department of Statistics Iowa State University Ames IA 50011 USA
| | - V. Mani
- Department of Animal Science Iowa State University Ames IA 50011 USA
| | - D. Nettleton
- Department of Statistics Iowa State University Ames IA 50011 USA
| | - J. M. Reecy
- Department of Animal Science Iowa State University Ames IA 50011 USA
| | - L. H. Baumgard
- Department of Animal Science Iowa State University Ames IA 50011 USA
| | | | - N. K. Gabler
- Department of Animal Science Iowa State University Ames IA 50011 USA
| | - J. W. Ross
- Department of Animal Science Iowa State University Ames IA 50011 USA
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13
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Rong J, Pass I, Diaz PW, Ngo TA, Sauer M, Magnuson G, Zeng FY, Hassig CA, Jackson MR, Cosford NDP, Matsuzawa SI, Reed JC. Cell-Based High-Throughput Luciferase Reporter Gene Assays for Identifying and Profiling Chemical Modulators of Endoplasmic Reticulum Signaling Protein, IRE1. ACTA ACUST UNITED AC 2015; 20:1232-45. [DOI: 10.1177/1087057115600414] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 07/22/2015] [Indexed: 01/23/2023]
Abstract
Endoplasmic reticulum (ER) stress activates three distinct signal transducers on the ER membrane. Inositol-requiring protein 1 (IRE1), the most conserved signal transducer, plays a key role in ER stress-mediated signaling. During ER stress, IRE1 initiates two discrete signaling cascades: the “adaptive” signaling cascade mediated by the XBP1 pathway and the “alarm” signaling cascade mediated by stress-activated protein kinase pathways. Fine-tuning of the balance between the adaptive and alarm signals contributes significantly to cellular fate under ER stress. Thus, we propose that the design of high-throughput screening (HTS) assays to selectively monitor IRE1 mediated-signaling would be desirable for drug discovery. To this end, we report the generation of stable human neural cell lines and development of cell-based HTS luciferase (Luc) reporter gene assays for the identification of pathway-specific chemical modulators of IRE1. We implemented a cell-based Luc assay using a chimeric CHOP-Gal4 transcription factor in 384-well format for monitoring IRE1 kinase-mediated p38MAPK activation and an unfolded response pathway element (URPE)–Luc cell-based assay in 1536-well format for monitoring IRE1’s RNase-mediated activation of XBP1. Chemical library screening was successfully conducted with both the CHOP/Gal4-Luc cells and UPRE-Luc engineered cells. The studies demonstrate the feasibility of using these HTS assays for discovery of pathway-selective modulators of IRE1.
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Affiliation(s)
- Juan Rong
- Cell Death and Survival Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Ian Pass
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Paul W. Diaz
- Cell Death and Survival Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Tram A. Ngo
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Michelle Sauer
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Gavin Magnuson
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Fu-Yue Zeng
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Christian A. Hassig
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Michael R. Jackson
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Nicholas D. P. Cosford
- Cell Death and Survival Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Shu-ichi Matsuzawa
- Cell Death and Survival Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - John C. Reed
- Cell Death and Survival Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
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14
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Dufey E, Sepúlveda D, Rojas-Rivera D, Hetz C. Cellular Mechanisms of Endoplasmic Reticulum Stress Signaling in Health and Disease. 1. An overview. Am J Physiol Cell Physiol 2014; 307:C582-94. [DOI: 10.1152/ajpcell.00258.2014] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Increased demand on the protein folding capacity of the endoplasmic reticulum (ER) engages an adaptive reaction known as the unfolded protein response (UPR). The UPR regulates protein translation and the expression of numerous target genes that contribute to restore ER homeostasis or induce apoptosis of irreversibly damaged cells. UPR signaling is highly regulated and dynamic and integrates information about the type, intensity, and duration of the stress stimuli, thereby determining cell fate. Recent advances highlight novel physiological outcomes of the UPR beyond specialized secretory cells, particularly in innate immunity, metabolism, and cell differentiation. Here we discuss studies on the fine-tuning of the UPR and its physiological role in diverse organs and diseases.
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Affiliation(s)
- Estefanie Dufey
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
| | - Denisse Sepúlveda
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
| | - Diego Rojas-Rivera
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
| | - Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile
- Program of Cellular and Molecular Biology, Institute of Biomedical Sciences, Center for Molecular Studies of the Cell, University of Chile, Santiago, Chile
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts; and
- Neurounion Biomedical Foundation, CENPAR, Santiago, Chile
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15
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Brewer JW. Regulatory crosstalk within the mammalian unfolded protein response. Cell Mol Life Sci 2014; 71:1067-79. [PMID: 24135849 PMCID: PMC11113126 DOI: 10.1007/s00018-013-1490-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 09/05/2013] [Accepted: 10/04/2013] [Indexed: 02/07/2023]
Abstract
Increased demands on the protein folding capacity of the endoplasmic reticulum (ER) trigger the unfolded protein response (UPR). Comprised of a tripartite signaling system, the UPR regulates translation and gene transcription to manifest pro-adaptive and, if necessary, pro-apoptotic outcomes. The three UPR pathways, initiated by activating transcription factor 6, inositol requiring enzyme 1, and protein kinase RNA-activated-like ER kinase (PERK), direct distinct downstream signaling events. However, it is becoming increasingly clear that interplay between the cascades is vital in shaping the UPR. In particular, recent discoveries have revealed that PERK-dependent signals mediate both inter- and intra-pathway regulation within the UPR, underscoring the critical role of the PERK pathway in the cellular response to ER stress.
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Affiliation(s)
- Joseph W Brewer
- Department of Molecular and Cellular Sciences, College of Osteopathic Medicine, Liberty University, 1971 University Boulevard, Lynchburg, VA, 24515, USA,
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16
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TMBIM protein family: ancestral regulators of cell death. Oncogene 2014; 34:269-80. [DOI: 10.1038/onc.2014.6] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/27/2013] [Accepted: 01/02/2014] [Indexed: 12/13/2022]
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17
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Abstract
Endoplasmic reticulum (ER) stress has been implicated in the pathophysiology of many diseases including heart disease, cancer and neurodegenerative diseases such as Alzheimer's and Huntington's. Prolonged or excessive ER stress results in the initiation of signaling pathways resulting in cell death. Over the past decade much research investigating the onset and progression of ER stress-induced cell death has been carried out. Owing to this we now have a better understanding of the signaling pathways leading to ER stress-mediated cell death and have begun to appreciate the importance of ER localized stress sensors, IRE1α, ATF6 and PERK in this process. In this article we provide an overview of the current thinking and concepts concerning the various stages of ER stress-induced cell death, focusing on the role of ER localized proteins in sensing and triggering ER stress-induced death signals with particular emphasis on the contribution of calcium signaling and Bcl-2 family members to the execution phase of this process. We also highlight new and emerging directions in ER stress-induced cell death research particularly the role of microRNAs, ER-mitochondria cross talk and the prospect of mitochondria-independent death signals in ER stress-induced cell death.
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Affiliation(s)
- Susan E Logue
- Apoptosis Research Centre, NUI Galway, Galway, Ireland
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18
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A novel RING finger E3 ligase RNF186 regulate ER stress-mediated apoptosis through interaction with BNip1. Cell Signal 2013; 25:2320-33. [PMID: 23896122 DOI: 10.1016/j.cellsig.2013.07.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/04/2013] [Accepted: 07/22/2013] [Indexed: 01/08/2023]
Abstract
Disturbances in the normal functions of the endoplasmic reticulum (ER) can lead to the accumulation of unfolded proteins and disturbance of Ca(2+) regulation within the lumen of ER, and arouse a series of complicated response termed unfolded protein response (UPR), which is aimed initially at reestablishing homeostasis and normal physiology but can ultimately trigger cell death if the UPR fails to compensate for damage. Here we show that ER locating human RING finger E3 ligase RNF186 participates in the process of ER stress-mediated apoptosis. Overexpression of RNF186 stimulates upregulation of ER sensor proteins and rapid transmission of ER Ca(2+) in Hela cells, while RNF186 knockdown exhibits a moderate degree of resistance to ER stress, indicating RNF186 can arouse stress signaling at ER. We further identified the Bcl-2 family protein BNip1 as one of the substrates of RNF186. BNip1 co-localizes with RNF186 at ER and is poly-ubiquitinated by RNF186 through K29 and K63 linkage in vivo. This modification promotes BNip1 transportation to mitochondria but has no influence on its protein level. The half-life of RNF186 is prolonged under ER stress, probably because of the inhibition on its self-ubiquitination and subsequent degradation by proteasomes. In addition, the ubiquitination of BNip1 is greatly enhanced when ER stress occurred, possibly due to RNF186 accumulation. More importantly, knockdown of BNip1 attenuates the stress signals at ER induced by RNF186. These results collectively indicate that BNip1 functions as a downstream modulator of RNF186 to direct ER stress-associated apoptotic signaling. Our study might reveal a novel E3 ligase-mediated mechanism for modulating ER stress.
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19
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Sano R, Reed JC. ER stress-induced cell death mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:3460-3470. [PMID: 23850759 DOI: 10.1016/j.bbamcr.2013.06.028] [Citation(s) in RCA: 1426] [Impact Index Per Article: 129.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 06/24/2013] [Accepted: 06/26/2013] [Indexed: 02/07/2023]
Abstract
The endoplasmic-reticulum (ER) stress response constitutes a cellular process that is triggered by a variety of conditions that disturb folding of proteins in the ER. Eukaryotic cells have developed an evolutionarily conserved adaptive mechanism, the unfolded protein response (UPR), which aims to clear unfolded proteins and restore ER homeostasis. In cases where ER stress cannot be reversed, cellular functions deteriorate, often leading to cell death. Accumulating evidence implicates ER stress-induced cellular dysfunction and cell death as major contributors to many diseases, making modulators of ER stress pathways potentially attractive targets for therapeutics discovery. Here, we summarize recent advances in understanding the diversity of molecular mechanisms that govern ER stress signaling in health and disease. This article is part of a Special Section entitled: Cell Death Pathways.
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Affiliation(s)
- Renata Sano
- Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA
| | - John C Reed
- Sanford-Burnham Medical Research Institute, La Jolla, CA, 92037, USA.
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20
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Vincenz L, Jäger R, O'Dwyer M, Samali A. Endoplasmic reticulum stress and the unfolded protein response: targeting the Achilles heel of multiple myeloma. Mol Cancer Ther 2013; 12:831-43. [PMID: 23729400 DOI: 10.1158/1535-7163.mct-12-0782] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Multiple myeloma is characterized by the malignant proliferating antibody-producing plasma cells in the bone marrow. Despite recent advances in therapy that improve the survival of patients, multiple myeloma remains incurable and therapy resistance is the major factor causing lethality. Clearly, more effective treatments are necessary. In recent years it has become apparent that, as highly secretory antibody-producing cells, multiple myeloma cells require an increased capacity to cope with unfolded proteins and are particularly sensitive to compounds targeting proteostasis such as proteasome inhibitors, which represent one of the most prominent new therapeutic strategies. Because of the increased requirement for dealing with secretory proteins within the endoplasmic reticulum, multiple myeloma cells are heavily reliant for survival on a set of signaling pathways, known as the unfolded protein response (UPR). Thus, directly targeting the UPR emerges as a new promising therapeutic strategy. Here, we provide an overview of the current understanding of the UPR signaling in cancer, and outline its important role in myeloma pathogenesis and treatment. We discuss new therapeutic approaches based on targeting the protein quality control machinery and particularly the IRE1α/XBP1 axis of the UPR.
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Affiliation(s)
- Lisa Vincenz
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland
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21
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Sancho-Martínez SM, Prieto-García L, Prieto M, López-Novoa JM, López-Hernández FJ. Subcellular targets of cisplatin cytotoxicity: An integrated view. Pharmacol Ther 2012; 136:35-55. [DOI: 10.1016/j.pharmthera.2012.07.003] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 06/28/2012] [Indexed: 12/29/2022]
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22
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Antiviral activity of a small molecule deubiquitinase inhibitor occurs via induction of the unfolded protein response. PLoS Pathog 2012; 8:e1002783. [PMID: 22792064 PMCID: PMC3390402 DOI: 10.1371/journal.ppat.1002783] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 05/16/2012] [Indexed: 12/11/2022] Open
Abstract
Ubiquitin (Ub) is a vital regulatory component in various cellular processes, including cellular responses to viral infection. As obligate intracellular pathogens, viruses have the capacity to manipulate the ubiquitin (Ub) cycle to their advantage by encoding Ub-modifying proteins including deubiquitinases (DUBs). However, how cellular DUBs modulate specific viral infections, such as norovirus, is poorly understood. To examine the role of DUBs during norovirus infection, we used WP1130, a small molecule inhibitor of a subset of cellular DUBs. Replication of murine norovirus in murine macrophages and the human norovirus Norwalk virus in a replicon system were significantly inhibited by WP1130. Chemical proteomics identified the cellular DUB USP14 as a target of WP1130 in murine macrophages, and pharmacologic inhibition or siRNA-mediated knockdown of USP14 inhibited murine norovirus infection. USP14 is a proteasome-associated DUB that also binds to inositol-requiring enzyme 1 (IRE1), a critical mediator of the unfolded protein response (UPR). WP1130 treatment of murine macrophages did not alter proteasome activity but activated the X-box binding protein-1 (XBP-1) through an IRE1-dependent mechanism. In addition, WP1130 treatment or induction of the UPR also reduced infection of other RNA viruses including encephalomyocarditis virus, Sindbis virus, and La Crosse virus but not vesicular stomatitis virus. Pharmacologic inhibition of the IRE1 endonuclease activity partially rescued the antiviral effect of WP1130. Taken together, our studies support a model whereby induction of the UPR through cellular DUB inhibition blocks specific viral infections, and suggest that cellular DUBs and the UPR represent novel targets for future development of broad spectrum antiviral therapies. Deubiquitinases (DUBs) are enzymes, which are implicated in many cellular processes but their functions during virus infection are not well understood. We used WP1130, a small molecule inhibitor of a subset of DUBs, as a probe to unravel the functions of DUBs during norovirus infections. We identified USP14 as a cellular DUB target of WP1130 that is required for optimal norovirus infection. Furthermore, we demonstrated that chemical induction of the unfolded protein response can significantly inhibit viral progeny production of several RNA viruses, including noroviruses. These results suggest that chemical inhibition of cellular DUBs and/or modulation of the unfolded protein response could represent novel targets for therapy against a variety of viral pathogens.
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23
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Chhangani D, Joshi AP, Mishra A. E3 ubiquitin ligases in protein quality control mechanism. Mol Neurobiol 2012; 45:571-85. [PMID: 22610945 DOI: 10.1007/s12035-012-8273-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 04/26/2012] [Indexed: 12/11/2022]
Abstract
In living cells, polypeptide chains emerging from ribosomes and preexisting polypeptide chains face constant threat of misfolding and aggregation. To prevent protein aggregation and to fulfill their biological activity, generally, protein must fold into its proper three-dimensional structure throughout their lifetimes. Eukaryotic cell possesses a quality control (QC) system to contend the problem of protein misfolding and aggregation. Cells achieve this functional QC system with the help of molecular chaperones and ubiquitin-proteasome system (UPS). The well-conserved UPS regulates the stability of various proteins and maintains all essential cellular function through intracellular protein degradation. E3 ubiquitin ligase enzyme determines specificity for degradation of certain substrates via UPS. New emerging evidences have provided considerable information that various E3 ubiquitin ligases play a major role in cellular QC mechanism and principally designated as QC E3 ubiquitin ligases. Nevertheless, very little is known about how E3 ubiquitin ligase maintains QC mechanism against abnormal proteins under various stress conditions. Here in this review, we highlight and discuss the functions of various E3 ubiquitin ligases implicated in protein QC mechanism. Improving our knowledge about such processes may provide opportunities to modulate protein QC mechanism in age-of-onset diseases that are caused by protein aggregation.
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Affiliation(s)
- Deepak Chhangani
- Biology Laboratory, Indian Institute of Technology Rajasthan, Jodhpur, 342011, India
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24
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Li H, Shi H, Huo K. p75NTR signal transduction suppressed by BFAR and p75NTR interactions. SCIENCE CHINA-LIFE SCIENCES 2012; 55:367-74. [PMID: 22566094 DOI: 10.1007/s11427-012-4306-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 03/02/2012] [Indexed: 11/26/2022]
Abstract
p75NTR is a low-affinity nerve growth factor receptor, which promotes cell proliferation as a positive modulator of high-affinity receptor TrkA, as well as binds with cell ligands to induce apoptosis and mediate death signals. To analyze the regulatory mechanisms of p75NTR, the present study utilized a new membrane yeast two-hybrid system to screen a human fetal brain cDNA library. Results identified BFAR, a novel protein that interacts with p75NTR. Interaction specificity was verified by membrane yeast two-hybrid co-transformation assays, in vitro GST pull-down assays, and in vitro co-immunoprecipitation assays. The fluorescent subcellular localization assay revealed that the two proteins co-localized within the cytoplasm. BFAR overexpression in PC-12 and HEK293T cells inhibited the NFκB and JNK signaling pathway, as determined with the luciferase test. Co-transfected p75NTR and BFAR in HEK293T or PC-12 cells, respectively, increased the percentage of cells in the G2/M phase, decreased the number of S-phase cells, and did not change the number of G0/G1-phase cells.
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Affiliation(s)
- Hongmei Li
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China
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25
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Jäger R, Bertrand MJM, Gorman AM, Vandenabeele P, Samali A. The unfolded protein response at the crossroads of cellular life and death during endoplasmic reticulum stress. Biol Cell 2012; 104:259-70. [PMID: 22268789 DOI: 10.1111/boc.201100055] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Accepted: 01/18/2012] [Indexed: 12/14/2022]
Abstract
One of the early cellular responses to endoplasmic reticulum (ER) stress is the activation of the unfolded protein response (UPR). ER stress and the UPR are both implicated in numerous human diseases and pathologies. In spite of this, our knowledge of the molecular mechanisms that regulate cell fate following ER stress is limited. The UPR is initiated by three ER transmembrane receptors: PKR-like ER kinase (PERK), activating transcription factor (ATF) 6 and inositol-requiring enzyme 1 (IRE1). These proteins sense the accumulation of unfolded proteins and their activation triggers specific adaptive responses to resolve the stress. Intriguingly, the very same receptors can initiate signalling pathways that lead to apoptosis when the attempts to resolve the ER stress fail. In this review, we describe the known pro-apoptotic signalling pathways emanating from activated PERK, ATF6 and IRE1 and discuss how their signalling switches from an adaptive to a pro-apoptotic response.
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Affiliation(s)
- Richard Jäger
- Apoptosis Research Centre, National University of Ireland Galway, Galway, Ireland
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26
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Gorman AM, Healy SJM, Jäger R, Samali A. Stress management at the ER: regulators of ER stress-induced apoptosis. Pharmacol Ther 2012; 134:306-16. [PMID: 22387231 DOI: 10.1016/j.pharmthera.2012.02.003] [Citation(s) in RCA: 290] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 02/01/2012] [Indexed: 12/18/2022]
Abstract
The endoplasmic reticulum (ER) is an elaborate cellular organelle essential for cell function and survival. Conditions that interfere with ER function lead to the accumulation and aggregation of unfolded proteins which are detected by ER transmembrane receptors that initiate the unfolded protein response (UPR) to restore normal ER function. If the ER stress is prolonged, or the adaptive response fails, apoptotic cell death ensues. Many studies have focused on how this failure initiates apoptosis, particularly because ER stress-induced apoptosis is implicated in the pathophysiology of several neurodegenerative and cardiovascular diseases. In this review we aim to shed light on the proteins that are not core components of the UPR signaling pathway but which can influence the course of the ER stress response by regulating the switch from the adaptive phase to apoptosis.
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Affiliation(s)
- Adrienne M Gorman
- Apoptosis Research Centre, School of Natural Sciences, National University of Ireland, Galway, University Road., Galway, Ireland
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27
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Hetz C. The unfolded protein response: controlling cell fate decisions under ER stress and beyond. Nat Rev Mol Cell Biol 2012; 13:89-102. [PMID: 22251901 DOI: 10.1038/nrm3270] [Citation(s) in RCA: 2769] [Impact Index Per Article: 230.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Protein-folding stress at the endoplasmic reticulum (ER) is a salient feature of specialized secretory cells and is also involved in the pathogenesis of many human diseases. ER stress is buffered by the activation of the unfolded protein response (UPR), a homeostatic signalling network that orchestrates the recovery of ER function, and failure to adapt to ER stress results in apoptosis. Progress in the field has provided insight into the regulatory mechanisms and signalling crosstalk of the three branches of the UPR, which are initiated by the stress sensors protein kinase RNA-like ER kinase (PERK), inositol-requiring protein 1α (IRE1α) and activating transcription factor 6 (ATF6). In addition, novel physiological outcomes of the UPR that are not directly related to protein-folding stress, such as innate immunity, metabolism and cell differentiation, have been revealed.
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Affiliation(s)
- Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, P.O. BOX 70086, Chile.
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28
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Sharma PL, Chunduri H, Wise J, Mindley R, Rimland D. Replication-independent expression of anti-apoptosis marker genes in human peripheral blood mononuclear cells infected with the wild-type HIV-1 and reverse transcriptase variants. Viral Immunol 2012; 25:12-20. [PMID: 22239233 DOI: 10.1089/vim.2011.0057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Clinical trials with highly-active antiretroviral therapy (HAART) have shown that a substantial number of patients continue to show a decrease in viral load and/or increase or stable CD4(+) T-cell numbers even in the presence of multidrug resistant (MDR) viruses. We compared replication capacity (RC) and expression of anti-apoptosis marker genes (AAMGs) in human peripheral blood mononuclear (PBM) cells infected with NL4-3 (wild-type; WT) and mutant viruses. Replication kinetics assays showed a significant decrease in RC of all mutant viruses in comparison to the WT virus. The viruses containing patient-derived MDR RT without the K65R mutation (PSD5.2) replicated efficiently in comparison to the viruses with MDR RT containing the K65R mutation (PSD5.1), or the single mutations K65R and M184V. Compared with WT, a significant decrease in RCs of viruses: K65R (RC=0.39±0.02; p≤0.0001), M184V (RC=0.72±0.04; p≤0.0001), PSD5.1 (RC=0.32±0.04; p≤0.0001), and PSD5.2 (RC=0.90±0.04; p=0.002) was observed on day 10. RT-PCR-based apoptosis array was performed on total cellular RNA. Recombinant virus PSD5.2 showed a 1.5- to 6-fold upregulation in 8 AAMGs (AKT1, BAG3, BCL2A1, BFAR, BIRC2, BNIP1, BNIP3, and CFLAR) on day 1 and day 7 post-infection with respect to WT virus. PSD5.1 showed upregulation of only one gene (BAG1) on day 1 (1.75-fold) and day 7 (1.97-fold). Point mutant K65R showed a 1.5- to 4-fold upregulation of six AAMGs on day 7. Viruses with the M184V mutation showed upregulation of only one gene (BAG1). These observations indicate that the upregulation of specific AAMGs may not be dependent on the RCs of HIV-I variants, and that the possible interaction among mutated RT residues and viral and/or host proteins may induce CD4(+) T-cell-protective anti-apoptosis proteins.
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Affiliation(s)
- Prem L Sharma
- Medical Research 151MV, Veterans Affairs Medical Center, Decatur, Georgia 30033, USA.
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29
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Kiviluoto S, Akl H, Vervliet T, Bultynck G, Parys JB, Missiaen L, De Smedt H. IP3 receptor-binding partners in cell-death mechanisms. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/wmts.5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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30
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Hetz C, Martinon F, Rodriguez D, Glimcher LH. The unfolded protein response: integrating stress signals through the stress sensor IRE1α. Physiol Rev 2011; 91:1219-43. [PMID: 22013210 DOI: 10.1152/physrev.00001.2011] [Citation(s) in RCA: 443] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Stress induced by accumulation of unfolded proteins at the endoplasmic reticulum (ER) is a classic feature of secretory cells and is observed in many tissues in human diseases including cancer, diabetes, obesity, and neurodegeneration. Cellular adaptation to ER stress is achieved by the activation of the unfolded protein response (UPR), an integrated signal transduction pathway that transmits information about the protein folding status at the ER to the nucleus and cytosol to restore ER homeostasis. Inositol-requiring transmembrane kinase/endonuclease-1 (IRE1α), the most conserved UPR stress sensor, functions as an endoribonuclease that processes the mRNA of the transcription factor X-box binding protein-1 (XBP1). IRE1α signaling is a highly regulated process, controlled by the formation of a dynamic scaffold onto which many regulatory components assemble, here referred to as the UPRosome. Here we provide an overview of the signaling and regulatory mechanisms underlying IRE1α function and discuss the emerging role of the UPR in adaptation to protein folding stress in specialized secretory cells and in pathological conditions associated with alterations in ER homeostasis.
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Affiliation(s)
- Claudio Hetz
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA.
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31
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Nakamura N. The Role of the Transmembrane RING Finger Proteins in Cellular and Organelle Function. MEMBRANES 2011; 1:354-93. [PMID: 24957874 PMCID: PMC4021871 DOI: 10.3390/membranes1040354] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 11/24/2011] [Accepted: 12/05/2011] [Indexed: 01/08/2023]
Abstract
A large number of RING finger (RNF) proteins are present in eukaryotic cells and the majority of them are believed to act as E3 ubiquitin ligases. In humans, 49 RNF proteins are predicted to contain transmembrane domains, several of which are specifically localized to membrane compartments in the secretory and endocytic pathways, as well as to mitochondria and peroxisomes. They are thought to be molecular regulators of the organization and integrity of the functions and dynamic architecture of cellular membrane and membranous organelles. Emerging evidence has suggested that transmembrane RNF proteins control the stability, trafficking and activity of proteins that are involved in many aspects of cellular and physiological processes. This review summarizes the current knowledge of mammalian transmembrane RNF proteins, focusing on their roles and significance.
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Affiliation(s)
- Nobuhiro Nakamura
- Department of Biological Sciences, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
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32
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Henke N, Lisak DA, Schneider L, Habicht J, Pergande M, Methner A. The ancient cell death suppressor BAX inhibitor-1. Cell Calcium 2011; 50:251-60. [PMID: 21663964 DOI: 10.1016/j.ceca.2011.05.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 05/03/2011] [Accepted: 05/05/2011] [Indexed: 10/18/2022]
Abstract
Bax inhibitor-1 (BI-1) was initially identified for its ability to inhibit BAX-induced apoptosis in yeast cells and is the founding member of a family of highly hydrophobic proteins localized in diverse cellular membranes. It is evolutionarily conserved and orthologues from plants can substitute for mammalian BI-1 in regard to its anti-apoptotic function suggesting a high degree of functional conservation. BI-1 interacts with BCL-2 and BCL-XL and, similar to these two anti-apoptotic proteins, the effect of BI-1 on cell death involves changes in the amount of Ca(2+) releasable from intracellular stores. However, BI-1 is also a negative regulator of the endoplasmic reticulum stress sensor IRE1 α, it interacts with G-actin and increases actin polymerization, enhances cancer metastasis by altering glucose metabolism and activating the sodium-hydrogen exchanger, and reduces the production of reactive oxygen species through direct interaction with NADPH-P450 reductase. In this contribution, we summarize what is known about the expression, intracellular localization and structure of BI-1 and specifically illuminate its effects on the intracellular Ca(2+) homeostasis and how this might relate to its other functions. We also present a thorough phylogenetic analysis of BI-1 proteins from major phyla together with paralogues from all BI-1 family members.
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Affiliation(s)
- Nadine Henke
- Neurologische Klinik, Universitätsklinikum Düsseldorf, Moorenstr. 5, D-40225 Düsseldorf, Germany
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Modulating stress responses by the UPRosome: a matter of life and death. Trends Biochem Sci 2011; 36:329-37. [PMID: 21482118 DOI: 10.1016/j.tibs.2011.03.001] [Citation(s) in RCA: 186] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Revised: 03/09/2011] [Accepted: 03/10/2011] [Indexed: 12/11/2022]
Abstract
The accumulation of unfolded proteins in the endoplasmic reticulum (ER) triggers the unfolded protein response (UPR) through the activation of specialized sensors including inositol-requiring enzyme-1α (IRE1α). IRE1α signals by assembling a dynamic protein platform referred to as the UPRosome, where different modulator and adaptor proteins assemble to regulate the kinetics and amplitude of UPR effector responses. Conversely, chronic ER stress can cause apoptosis. Recent evidence indicates that several apoptosis-related proteins interact with IRE1α, regulating its prosurvival activities and performing a dual function in the regulation of cell death and adaptation to stress. Based on the increasing relevance of ER stress to the occurrence of diverse pathological conditions, strategies to target and modulate the assembly and composition of the UPRosome could have therapeutic benefits for disease intervention.
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Robinson KS, Clements A, Williams AC, Berger CN, Frankel G. Bax Inhibitor 1 in apoptosis and disease. Oncogene 2011; 30:2391-400. [DOI: 10.1038/onc.2010.636] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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