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Liu Y, Zhao Y, Wu J, Liu T, Tang M, Yao Y, Xue P, He M, Xu Y, Zhang P, Gu M, Qu W, Zhang Y. Lithium impacts the function of hematopoietic stem cells via disturbing the endoplasmic reticulum stress and Hsp90 signaling. Food Chem Toxicol 2023; 181:114081. [PMID: 37783420 DOI: 10.1016/j.fct.2023.114081] [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: 07/31/2023] [Revised: 09/18/2023] [Accepted: 09/29/2023] [Indexed: 10/04/2023]
Abstract
Lithium (Li) has been widely used in clinical therapy and new Li-ion battery industry. To date, the impact of Li on the development of immune cells is largely unknown. The aim of this study was to investigate the impact of Li on hematopoiesis. C57BL/6 (B6) mice were treated with 50 ppm LiCl, 200 ppm LiCl, or the control via drinking water for 3 months, and thereafter the hematopoiesis was evaluated. Treatment with Li increased the number of mature lymphoid cells while suppressing the number of mature myeloid cells in mice. In addition, a direct action of Li on hematopoietic stem cells (HSC) suppressed endoplasmic reticulum (ER) stress to reduce the proliferation of HSC in the bone marrow (BM), thus leading to fewer HSC in mice. On the other hand, the suppression of ER stress by Li exposure increased the expression of Hsp90, which promoted the potential of lymphopoiesis but did not impact that for myelopoiesis in HSC in the BM of mice. Moreover, in vitro treatment with Li also likely disturbed the ER stress-Hsp90 signaling, suppressed the proliferation, and increased the potential for lymphopoiesis in human HSC. Our study reveals a previously unrecognized toxicity of Li on HSC and may advance our understanding for the immunotoxicology of Li.
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Affiliation(s)
- Yalin Liu
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - Yifan Zhao
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - Jiaojiao Wu
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - Ting Liu
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - MengKe Tang
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - Ye Yao
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - Peng Xue
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - Miao He
- State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Yanyi Xu
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - Peng Zhang
- Huzhou Center for Disease Control and Prevention, Zhejiang, 313000, China.
| | - Minghua Gu
- Shanghai Municipal Center for Disease Control & Prevention, Shanghai, 200336, China.
| | - Weidong Qu
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China
| | - Yubin Zhang
- School of Public Health and Key Laboratory of Public Health Safety, MOE, Fudan University, Shanghai, 200032, China.
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黄 浩, 乔 妤, 黄 奕, 董 航. [HSP90α exacerbates house dust mite-induced asthmatic airway inflammation by upregulating endoplasmic reticulum stress in bronchial epithelial cells]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2022; 42:347-353. [PMID: 35426797 PMCID: PMC9010984 DOI: 10.12122/j.issn.1673-4254.2022.03.05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Indexed: 06/14/2023]
Abstract
OBJECTIVE To explore the role of heat shock protein 90α (HSP90α) and endoplasmic reticulum (ER) stress pathway in allergic airway inflammation induced by house dust mite (HDM) in bronchial epithelial cells. METHODS A HDM- induced asthmatic cell model was established in human bronchial epithelial (HBE) cells by exposure to a concentration gradient (200, 400 and 800 U/mL) of HDM for 24 h. To test the effect of siHSP90α and HSP90 inhibitor 17-AAG on HDM-induced asthmatic inflammation, HBE cells were transfected with siHSP90α (50 nmol, 12 h) or pretreated with 17-AAG (900 nmol, 6 h) prior to HDM exposure (800 U/mL) for 24 h, and the changes in the expression of HSP90α and ER stress markers were assessed. We also tested the effect of nasal drip of 17-AAG, HDM, or their combination on airway inflammation and ER stress in C57BL/6 mice. RESULTS In HBE cells, HDM exposure significantly up-regulated the expression of HSP90α protein (P=0.011) and ER stress markers XBP-1 (P=0.044), ATF-6α (P=0.030) and GRP-78 (P=0.027). Knocking down HSP90α and treatment with 17-AAG both significantly inhibited HDM-induced upregulation of XBP-1 (P=0.008). In C57BL/6 mice, treatment with 17-AAG obviously improved HDM-induced airway inflammation and significantly reduced the number of inflammatory cells in the airway (P=0.014) and lowered the levels of IL-4 (P=0.030) and IL-5 (P=0.035) in alveolar lavage fluid. Immunohistochemical staining showed that the expressions of XBP-1 and GRP-78 in airway epithelial cells decreased significantly after the treatment of 17-AAG. CONCLUSIONS HSP90α promotes HDM-induced airway allergic inflammation possibly by upregulating ER stress pathway in bronchial epithelial cells.
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Affiliation(s)
- 浩华 黄
- />南方医科大学南方医院呼吸与危重症医学科,广东 广州 510515Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - 妤婕 乔
- />南方医科大学南方医院呼吸与危重症医学科,广东 广州 510515Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - 奕 黄
- />南方医科大学南方医院呼吸与危重症医学科,广东 广州 510515Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - 航明 董
- />南方医科大学南方医院呼吸与危重症医学科,广东 广州 510515Department of Respiratory and Critical Care Medicine, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
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Evers F, Cabrera-Orefice A, Elurbe DM, Kea-Te Lindert M, Boltryk SD, Voss TS, Huynen MA, Brandt U, Kooij TWA. Composition and stage dynamics of mitochondrial complexes in Plasmodium falciparum. Nat Commun 2021; 12:3820. [PMID: 34155201 PMCID: PMC8217502 DOI: 10.1038/s41467-021-23919-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 05/21/2021] [Indexed: 12/19/2022] Open
Abstract
Our current understanding of mitochondrial functioning is largely restricted to traditional model organisms, which only represent a fraction of eukaryotic diversity. The unusual mitochondrion of malaria parasites is a validated drug target but remains poorly understood. Here, we apply complexome profiling to map the inventory of protein complexes across the pathogenic asexual blood stages and the transmissible gametocyte stages of Plasmodium falciparum. We identify remarkably divergent composition and clade-specific additions of all respiratory chain complexes. Furthermore, we show that respiratory chain complex components and linked metabolic pathways are up to 40-fold more prevalent in gametocytes, while glycolytic enzymes are substantially reduced. Underlining this functional switch, we find that cristae are exclusively present in gametocytes. Leveraging these divergent properties and stage dynamics for drug development presents an attractive opportunity to discover novel classes of antimalarials and increase our repertoire of gametocytocidal drugs.
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Affiliation(s)
- Felix Evers
- Department of Medical Microbiology, Radboudumc Center for Infectious Diseases, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Alfredo Cabrera-Orefice
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Dei M Elurbe
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Mariska Kea-Te Lindert
- Electron Microscopy Center, RTC Microscopy, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Cell Biology, Radboud Institute of Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Sylwia D Boltryk
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Martijn A Huynen
- Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Ulrich Brandt
- Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Taco W A Kooij
- Department of Medical Microbiology, Radboudumc Center for Infectious Diseases, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands.
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Zhang H, Ge F, Shui X, Xiang Y, Wang X, Liao C, Wang J. NIX protein enhances antioxidant capacity of and reduces the apoptosis induced by HSP90 inhibitor luminespib/NVP-AUY922 in PC12 cells. Cell Stress Chaperones 2021; 26:495-504. [PMID: 33629253 PMCID: PMC8065087 DOI: 10.1007/s12192-021-01193-6] [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: 07/01/2020] [Revised: 01/20/2021] [Accepted: 01/28/2021] [Indexed: 11/29/2022] Open
Abstract
Pheochromocytomas and paragangliomas (PCPGs) are catecholamine-producing neuroendocrine tumors. Accumulating evidences indicate that the blockade of antioxidative pathways might be a novel therapeutic approach to the treatment of PCPG. NIX has been confirmed to play a key role in maintaining redox homeostasis in tumors, while the function of NIX in PCPG remains unclear. In this study, the analyses of the disease-free survival (DFS) showed that high NIX protein level is related to poor prognosis in patients of PCPG. Consistent with this, high level of NIX protein upregulates the level of p-NF-κB and promotes the migration of PC12 cells. In NIX-over-expressing PC12 cells, the level of reactive oxygen species (ROS) is decreased while trolox-equivalent antioxidant capacity (TEAC) increased. But in NIX-silencing cells, ROS level is increased, while TEAC reversely reduced, consequently antioxidase and phase II enzymes of NRF2 signaling were activated, and elevated endoplasmic reticulum (ER) stress was observed. Additionally, the apoptosis induced by luminespib/NVP-AUY922, an inhibitor of heat shock protein 90 (HSP90, a cellular stress response factor), was enhanced in NIX-silencing cells but reduced in the NIX-over-expressing cells. All of these results indicated that high NIX protein level enhances antioxidant capacity of PC12 cells and reduces the apoptosis caused by cell stress, such as induced by luminespib/NVP-AUY922. Therefore, luminespib/NVP-AUY922 might be effective only for PCPG with low NIX level, while targeting NIX could be a further supplement to the therapeutic treatment strategy for PCPG patients with high NIX protein level.
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Affiliation(s)
- Hong Zhang
- School of Laboratory Medicine/Sichuan Provincial Engineering Laboratory for Prevention and Control Technology of Veterinary Drug Residue in Animal-origin Food, Chengdu Medical College, Chengdu, 610500, Sichuan, China
| | - Fanghui Ge
- School of Laboratory Medicine/Sichuan Provincial Engineering Laboratory for Prevention and Control Technology of Veterinary Drug Residue in Animal-origin Food, Chengdu Medical College, Chengdu, 610500, Sichuan, China
| | - Xindong Shui
- School of Bioscience and Technology, Chengdu Medical College, Chengdu, 610500, Sichuan, China
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China
| | - Yuling Xiang
- School of Bioscience and Technology, Chengdu Medical College, Chengdu, 610500, Sichuan, China
- College of Life Science and Technology, Guangxi University, Nanning, 530004, Guangxi, China
| | - Xinxin Wang
- School of Laboratory Medicine/Sichuan Provincial Engineering Laboratory for Prevention and Control Technology of Veterinary Drug Residue in Animal-origin Food, Chengdu Medical College, Chengdu, 610500, Sichuan, China
| | - Chang Liao
- School of Laboratory Medicine/Sichuan Provincial Engineering Laboratory for Prevention and Control Technology of Veterinary Drug Residue in Animal-origin Food, Chengdu Medical College, Chengdu, 610500, Sichuan, China
| | - Jiandong Wang
- School of Bioscience and Technology, Chengdu Medical College, Chengdu, 610500, Sichuan, China.
- Collaborative Innovation Center of Sichuan for Elderly Care and Health, Chengdu Medical College, Chengdu, 610500, Sichuan, China.
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The Hsp70-Hsp90 go-between Hop/Stip1/Sti1 is a proteostatic switch and may be a drug target in cancer and neurodegeneration. Cell Mol Life Sci 2021; 78:7257-7273. [PMID: 34677645 PMCID: PMC8629791 DOI: 10.1007/s00018-021-03962-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 08/24/2021] [Accepted: 09/24/2021] [Indexed: 01/17/2023]
Abstract
The Hsp70 and Hsp90 molecular chaperone systems are critical regulators of protein homeostasis (proteostasis) in eukaryotes under normal and stressed conditions. The Hsp70 and Hsp90 systems physically and functionally interact to ensure cellular proteostasis. Co-chaperones interact with Hsp70 and Hsp90 to regulate and to promote their molecular chaperone functions. Mammalian Hop, also called Stip1, and its budding yeast ortholog Sti1 are eukaryote-specific co-chaperones, which have been thought to be essential for substrate ("client") transfer from Hsp70 to Hsp90. Substrate transfer is facilitated by the ability of Hop to interact simultaneously with Hsp70 and Hsp90 as part of a ternary complex. Intriguingly, in prokaryotes, which lack a Hop ortholog, the Hsp70 and Hsp90 orthologs interact directly. Recent evidence shows that eukaryotic Hsp70 and Hsp90 can also form a prokaryote-like binary chaperone complex in the absence of Hop, and that this binary complex displays enhanced protein folding and anti-aggregation activities. The canonical Hsp70-Hop-Hsp90 ternary chaperone complex is essential for optimal maturation and stability of a small subset of clients, including the glucocorticoid receptor, the tyrosine kinase v-Src, and the 26S/30S proteasome. Whereas many cancers have increased levels of Hop, the levels of Hop decrease in the aging human brain. Since Hop is not essential in all eukaryotic cells and organisms, tuning Hop levels or activity might be beneficial for the treatment of cancer and neurodegeneration.
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Miller-Vedam LE, Bräuning B, Popova KD, Schirle Oakdale NT, Bonnar JL, Prabu JR, Boydston EA, Sevillano N, Shurtleff MJ, Stroud RM, Craik CS, Schulman BA, Frost A, Weissman JS. Structural and mechanistic basis of the EMC-dependent biogenesis of distinct transmembrane clients. eLife 2020; 9:e62611. [PMID: 33236988 PMCID: PMC7785296 DOI: 10.7554/elife.62611] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022] Open
Abstract
Membrane protein biogenesis in the endoplasmic reticulum (ER) is complex and failure-prone. The ER membrane protein complex (EMC), comprising eight conserved subunits, has emerged as a central player in this process. Yet, we have limited understanding of how EMC enables insertion and integrity of diverse clients, from tail-anchored to polytopic transmembrane proteins. Here, yeast and human EMC cryo-EM structures reveal conserved intricate assemblies and human-specific features associated with pathologies. Structure-based functional studies distinguish between two separable EMC activities, as an insertase regulating tail-anchored protein levels and a broader role in polytopic membrane protein biogenesis. These depend on mechanistically coupled yet spatially distinct regions including two lipid-accessible membrane cavities which confer client-specific regulation, and a non-insertase EMC function mediated by the EMC lumenal domain. Our studies illuminate the structural and mechanistic basis of EMC's multifunctionality and point to its role in differentially regulating the biogenesis of distinct client protein classes.
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Affiliation(s)
- Lakshmi E Miller-Vedam
- Molecular, Cellular, and Computational Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Bastian Bräuning
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Katerina D Popova
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Biomedical Sciences Graduate Program, University of California, San FranciscoSan FranciscoUnited States
| | - Nicole T Schirle Oakdale
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Jessica L Bonnar
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Jesuraj R Prabu
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Elizabeth A Boydston
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Natalia Sevillano
- Department of Pharmaceutical Chemistry, University of California, San FranciscoSan FranciscoUnited States
| | - Matthew J Shurtleff
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Charles S Craik
- Department of Pharmaceutical Chemistry, University of California, San FranciscoSan FranciscoUnited States
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Jonathan S Weissman
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical InstituteChevy ChaseUnited States
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Bai L, You Q, Feng X, Kovach A, Li H. Structure of the ER membrane complex, a transmembrane-domain insertase. Nature 2020; 584:475-478. [PMID: 32494008 PMCID: PMC7442705 DOI: 10.1038/s41586-020-2389-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 04/07/2020] [Indexed: 11/24/2022]
Abstract
The ER membrane complex (EMC) cooperates with the Sec61 translocon to co-translationally insert a transmembrane helix (TMH) of many multi-pass integral membrane proteins into the ER membrane, and it is also responsible for inserting the TMH of some tail-anchored proteins 1–3. How EMC accomplishes this feat has been unclear. Here we report the first cryo-EM structure of the eukaryotic EMC. We found that the Saccharomyces cerevisiae EMC contains eight subunits (Emc1–6, 7, and 10); has a large lumenal region and a smaller cytosolic region; and has a transmembrane region formed by Emc4, 5, and 6 plus the transmembrane domains (TMDs) of Emc1 and 3. We identified a 5-TMH fold centered around Emc3 that resembles the prokaryotic insertase YidC and that delineates a largely hydrophilic client pocket. The TMD of Emc4 tilts away from the main transmembrane region of EMC and is partially mobile. Mutational studies demonstrated that Emc4 flexibility and the hydrophilicity of the client pocket are required for EMC function. The EMC structure reveals a remarkable evolutionary conservation with the prokaryotic insertases 4,5; suggests a similar mechanism of TMH insertion; and provides a framework for detailed understanding of membrane insertion for numerous eukaryotic integral membrane proteins and tail-anchored proteins.
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Affiliation(s)
- Lin Bai
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA.
| | - Qinglong You
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Xiang Feng
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Amanda Kovach
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Huilin Li
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA.
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SNX-2112, an Hsp90 inhibitor, suppresses cervical cancer cells proliferation, migration, and invasion by inhibiting the Akt/mTOR signaling pathway. Med Chem Res 2020. [DOI: 10.1007/s00044-020-02534-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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9
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Volkmar N, Christianson JC. Squaring the EMC - how promoting membrane protein biogenesis impacts cellular functions and organismal homeostasis. J Cell Sci 2020; 133:133/8/jcs243519. [PMID: 32332093 PMCID: PMC7188443 DOI: 10.1242/jcs.243519] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Integral membrane proteins play key functional roles at organelles and the plasma membrane, necessitating their efficient and accurate biogenesis to ensure appropriate targeting and activity. The endoplasmic reticulum membrane protein complex (EMC) has recently emerged as an important eukaryotic complex for biogenesis of integral membrane proteins by promoting insertion and stability of atypical and sub-optimal transmembrane domains (TMDs). Although confirmed as a bona fide complex almost a decade ago, light is just now being shed on the mechanism and selectivity underlying the cellular responsibilities of the EMC. In this Review, we revisit the myriad of functions attributed the EMC through the lens of these new mechanistic insights, to address questions of the cellular and organismal roles the EMC has evolved to undertake. Summary: The EMC is an important factor facilitating membrane protein biogenesis. Here we discuss the broad cellular and organismal responsibilities overseen by client proteins requiring the EMC for maturation.
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Affiliation(s)
- Norbert Volkmar
- Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - John C Christianson
- Oxford Centre for Translational Myeloma Research, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Headington, Oxford OX3 7LD, UK
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