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DiGuilio A, Cheng B, Zhong F, Jha R, Wan Y, Anghel SA, Hu H, Shishkova E, Ji Z, Coon JJ, Keenan RJ. The prolyl isomerase FKBP11 is a secretory translocon accessory factor. Mol Biol Cell 2024; 35:ar135. [PMID: 39259761 DOI: 10.1091/mbc.e24-07-0305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2024] Open
Abstract
Eukaryotic cells encode thousands of secretory and membrane proteins, many of which are cotranslationally translocated into the endoplasmic reticulum (ER). Nascent polypeptides entering the ER encounter a network of molecular chaperones and enzymes that facilitate their folding. A rate-limiting step for some proteins is the trans-to-cis isomerization of the peptide bond between proline and the residue preceding it. The human ER contains six prolyl isomerases, but the function, organization, and substrate range of these proteins is not clear. Here we show that the metazoan-specific, prolyl isomerase FKBP11 binds to ribosome-translocon complexes (RTCs) in the ER membrane, dependent on its single transmembrane domain and a conserved, positively charged region at its cytosolic C-terminus. High-throughput mRNA sequencing shows selective engagement with ribosomes synthesizing secretory and membrane proteins with long translocated segments, and functional analysis shows reduced stability of two such proteins, EpCAM and PTTG1IP, in cells depleted of FKBP11. We propose that FKBP11 is a translocon accessory factor that acts on a broad range of soluble secretory and transmembrane proteins during their synthesis at the ER.
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Affiliation(s)
- Amanda DiGuilio
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Ben Cheng
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Frank Zhong
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
| | - Roshan Jha
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Yu Wan
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60628
| | - S Andrei Anghel
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637
| | - Hong Hu
- Center for Research Informatics, The University of Chicago, Chicago, IL 60637
| | - Evgenia Shishkova
- National Center for Quantitative Biology of Complex Systems, Madison, WI 53706
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706
| | - Zhe Ji
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60628
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Joshua J Coon
- National Center for Quantitative Biology of Complex Systems, Madison, WI 53706
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706
- Morgridge Institute for Research, Madison, WI 53515
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53506
| | - Robert J Keenan
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637
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Page KR, Nguyen VN, Pleiner T, Tomaleri GP, Wang ML, Guna A, Hazu M, Wang TY, Chou TF, Voorhees RM. Role of a holo-insertase complex in the biogenesis of biophysically diverse ER membrane proteins. Mol Cell 2024; 84:3302-3319.e11. [PMID: 39173640 DOI: 10.1016/j.molcel.2024.08.005] [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: 08/30/2023] [Revised: 04/19/2024] [Accepted: 08/02/2024] [Indexed: 08/24/2024]
Abstract
Mammalian membrane proteins perform essential physiologic functions that rely on their accurate insertion and folding at the endoplasmic reticulum (ER). Using forward and arrayed genetic screens, we systematically studied the biogenesis of a panel of membrane proteins, including several G-protein-coupled receptors (GPCRs). We observed a central role for the insertase, the ER membrane protein complex (EMC), and developed a dual-guide approach to identify genetic modifiers of the EMC. We found that the back of Sec61 (BOS) complex, a component of the multipass translocon, was a physical and genetic interactor of the EMC. Functional and structural analysis of the EMC⋅BOS holocomplex showed that characteristics of a GPCR's soluble domain determine its biogenesis pathway. In contrast to prevailing models, no single insertase handles all substrates. We instead propose a unifying model for coordination between the EMC, the multipass translocon, and Sec61 for the biogenesis of diverse membrane proteins in human cells.
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Affiliation(s)
- Katharine R Page
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Vy N Nguyen
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Tino Pleiner
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Giovani Pinton Tomaleri
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Maxine L Wang
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Alina Guna
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Masami Hazu
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Ting-Yu Wang
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.
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3
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Chen K, Wang Y, Yang J, Klöting N, Liu C, Dai J, Jin S, Chen L, Liu S, Liu Y, Yu Y, Liu X, Miao Q, Liew CW, Wang Y, Dietrich A, Blüher M, Wang X. EMC10 modulates hepatic ER stress and steatosis in an isoform-specific manner. J Hepatol 2024; 81:479-491. [PMID: 38599383 DOI: 10.1016/j.jhep.2024.03.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 04/12/2024]
Abstract
BACKGROUND & AIMS Endoplasmic reticulum (ER) membrane protein complex subunit 10 (EMC10) has been implicated in obesity. Here we investigated the roles of the two isoforms of EMC10, including a secreted isoform (scEMC10) and an ER membrane-bound isoform (mEMC10), in metabolic dysfunction-associated steatotic liver disease (MASLD). METHODS Manifold steatotic mouse models and HepG2 cells were employed to investigate the role of EMC10 in the regulation of hepatic PERK-eIF2α-ATF4 signaling and hepatosteatosis. The therapeutic effect of scEMC10-neutralizing antibody on mouse hepatosteatosis was explored. Associations of MASLD with serum scEMC10 and hepatic mEMC10 were determined in two cohorts of participants with MASLD. RESULTS scEMC10 promoted, while mEMC10 suppressed, the activation of hepatic PERK-eIF2α-ATF4 signaling. Emc10 gene knockout exacerbated, while hepatic overexpression of mEMC10 ameliorated, hepatic ER stress and steatosis in mice challenged with either a methionine- and choline-deficient diet or tunicamycin, highlighting a direct, suppressive role of mEMC10 in MASLD via modulation of hepatic ER stress. Overexpression of scEMC10 promoted, whereas neutralization of circulating scEMC10 prevented, hepatosteatosis in mice with fatty liver, suggesting a role of scEMC10 in MASLD development. Clinically, serum scEMC10 was increased, while hepatic mEMC10 was decreased, in participants with MASLD. Correlative analysis indicated that serum scEMC10 positively, whereas hepatic mEMC10 negatively, correlated with liver fat content and serum ALT, AST, and GGT. CONCLUSIONS These findings demonstrate a novel isoform-specific role for EMC10 in the pathogenesis of MASLD and identify the secreted isoform as a tractable therapeutic target for MASLD via antibody-based neutralization. IMPACT AND IMPLICATIONS We have shown the role of EMC10 in the regulation of energy homeostasis and obesity. In this study, we determine the distinct roles of the two isoforms of EMC10 in the regulation of hepatic endoplasmic reticulum stress and steatosis in mice, and report on the associations of the different EMC10 isoforms with metabolic dysfunction-associated steatotic liver disease in humans. Our findings delineate a novel regulatory axis for hepatosteatosis and identify EMC10 as a modulator of the PERK-eIF2α-ATF4 signaling cascade that may be of broad physiological significance. Moreover, our pre-clinical and clinical studies provide evidence of the therapeutic potential of targeting scEMC10 in MASLD.
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Affiliation(s)
- Kuangyang Chen
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China; Department of Endocrinology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yahao Wang
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jia Yang
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Nora Klöting
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany; Medical Department III - Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
| | - Chuanfeng Liu
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Jiarong Dai
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Shuoshuo Jin
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Lijiao Chen
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Shan Liu
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yuzhao Liu
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yongzhuo Yu
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Xiaoxia Liu
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Qing Miao
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Chong Wee Liew
- Department of Physiology & Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Yangang Wang
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Arne Dietrich
- Department of Visceral, Transplant, Thoracic and Vascular Surgery, University Hospital Leipzig, Leipzig, Germany
| | - Matthias Blüher
- Helmholtz Institute for Metabolic, Obesity and Vascular Research (HI-MAG) of the Helmholtz Zentrum München at the University of Leipzig and University Hospital Leipzig, Leipzig, Germany; Medical Department III - Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, Leipzig, Germany
| | - Xuanchun Wang
- Department of Endocrinology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China.
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Uemura S, Mochizuki T, Kato Y, Mioka T, Watanabe R, Fuchita M, Yamada M, Noda Y, Moriguchi T, Abe F. Mtc6/Ehg2 is a novel endoplasmic reticulum-resident glycoprotein essential for high-pressure tolerance. J Biochem 2024; 176:155-166. [PMID: 38621657 DOI: 10.1093/jb/mvae035] [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: 01/28/2024] [Revised: 04/01/2024] [Accepted: 04/03/2024] [Indexed: 04/17/2024] Open
Abstract
Hydrostatic pressure is a common mechanical stressor that modulates metabolism and reduces cell viability. Eukaryotic cells have genetic programs to cope with hydrostatic pressure stress and maintain intracellular homeostasis. However, the mechanism underlying hydrostatic pressure tolerance remains largely unknown. We have recently demonstrated that maintenance of telomere capping protein 6 (Mtc6) plays a protective role in the survival of the budding yeast Saccharomyces cerevisiae under hydrostatic pressure stress by supporting the integrity of nutrient permeases. The current study demonstrates that Mtc6 acts as an endoplasmic reticulum (ER) membrane protein. Mtc6 comprises two transmembrane domains, a C-terminal cytoplasmic domain and a luminal region with 12 Asn (N)-linked glycans attached to it. Serial mutational analyses showed that the cytoplasmic C-terminal amino acid residues GVPS Mtc6 activity. Multiple N-linked glycans in the luminal region are involved in the structural conformation of Mtc6. Moreover, deletion of MTC6 led to increased degradation of the leucine permease Bap2 under hydrostatic pressure, suggesting that Mtc6 facilitates the proper folding of nutrient permeases in the ER under stress conditions. We propose a novel model of molecular function in which the glycosylated luminal domain and cytoplasmic GVPS sequences of Mtc6 cooperatively support the nutrient permease activity.
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Affiliation(s)
- Satoshi Uemura
- Division of Medical Biochemistry, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai, 983-8536, Japan
| | - Takahiro Mochizuki
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
| | - Yusuke Kato
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
| | - Tetsuo Mioka
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
| | - Riseko Watanabe
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
| | - Mai Fuchita
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
| | - Mao Yamada
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
| | - Yoichi Noda
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo,113-8657, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo,113-8657, Japan
| | - Takashi Moriguchi
- Division of Medical Biochemistry, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1 Fukumuro, Miyagino-ku, Sendai, 983-8536, Japan
| | - Fumiyoshi Abe
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, 252-5258, Japan
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5
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Davies JP, Plate L. The glycoprotein quality control factor Malectin promotes coronavirus replication and viral protein biogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.02.597051. [PMID: 38895409 PMCID: PMC11185542 DOI: 10.1101/2024.06.02.597051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Coronaviruses (CoV) rewire host protein homeostasis (proteostasis) networks through interactions between viral nonstructural proteins (nsps) and host factors to promote infection. With the emergence of SARS-CoV-2, it is imperative to characterize host interactors shared across nsp homologs. Using quantitative proteomics and functional genetic screening, we identify conserved proteostasis interactors of nsp2 and nsp4 that serve pro-viral roles during infection of murine hepatitis virus - a model betacoronavirus. We uncover a glycoprotein quality control factor, Malectin (MLEC), which significantly reduces infectious titers when knocked down. During infection, nsp2 interacts with MLEC-associated proteins and the MLEC-interactome is drastically altered, stabilizing association with the Oligosaccheryltransferase (OST) complex, a crucial component of viral glycoprotein production. MLEC promotes viral protein levels and genome replication through its quality control activity. Lastly, we show MLEC promotes SARS-CoV-2 replication. Our results reveal a role for MLEC in mediating CoV infection and identify a potential target for pan-CoV antivirals.
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Affiliation(s)
- Jonathan P. Davies
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, 37235
- Vanderbilt Institute of Infection, Immunology and Inflammation, Nashville, TN, 37235
| | - Lars Plate
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, 37235
- Vanderbilt Institute of Infection, Immunology and Inflammation, Nashville, TN, 37235
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, 37235
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Hegde RS, Keenan RJ. A unifying model for membrane protein biogenesis. Nat Struct Mol Biol 2024; 31:1009-1017. [PMID: 38811793 PMCID: PMC7616256 DOI: 10.1038/s41594-024-01296-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 03/25/2024] [Indexed: 05/31/2024]
Abstract
α-Helical integral membrane proteins comprise approximately 25% of the proteome in all organisms. The membrane proteome is highly diverse, varying in the number, topology, spacing and properties of transmembrane domains. This diversity imposes different constraints on the insertion of different regions of a membrane protein into the lipid bilayer. Here, we present a cohesive framework to explain membrane protein biogenesis, in which different parts of a nascent substrate are triaged between Oxa1 and SecY family members for insertion. In this model, Oxa1 family proteins insert transmembrane domains flanked by short translocated segments, whereas the SecY channel is required for insertion of transmembrane domains flanked by long translocated segments. Our unifying model rationalizes evolutionary, genetic, biochemical and structural data across organisms and provides a foundation for future mechanistic studies of membrane protein biogenesis.
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Affiliation(s)
- Ramanujan S Hegde
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
| | - Robert J Keenan
- Gordon Center for Integrative Science, The University of Chicago, Chicago, IL, USA.
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Lewis AJO, Zhong F, Keenan RJ, Hegde RS. Structural analysis of the dynamic ribosome-translocon complex. eLife 2024; 13:RP95814. [PMID: 38896445 PMCID: PMC11186639 DOI: 10.7554/elife.95814] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024] Open
Abstract
The protein translocon at the endoplasmic reticulum comprises the Sec61 translocation channel and numerous accessory factors that collectively facilitate the biogenesis of secretory and membrane proteins. Here, we leveraged recent advances in cryo-electron microscopy (cryo-EM) and structure prediction to derive insights into several novel configurations of the ribosome-translocon complex. We show how a transmembrane domain (TMD) in a looped configuration passes through the Sec61 lateral gate during membrane insertion; how a nascent chain can bind and constrain the conformation of ribosomal protein uL22; and how the translocon-associated protein (TRAP) complex can adjust its position during different stages of protein biogenesis. Most unexpectedly, we find that a large proportion of translocon complexes contains RAMP4 intercalated into Sec61's lateral gate, widening Sec61's central pore and contributing to its hydrophilic interior. These structures lead to mechanistic hypotheses for translocon function and highlight a remarkably plastic machinery whose conformations and composition adjust dynamically to its diverse range of substrates.
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Affiliation(s)
- Aaron JO Lewis
- MRC Laboratory of Molecular BiologyCambridgeUnited Kingdom
| | - Frank Zhong
- Department of Molecular Genetics and Cell Biology, The University of ChicagoChicagoUnited States
| | - Robert J Keenan
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
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8
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Mei N, Gong S, Wang L, Wang L, Wang J, Li J, Bao Y, Zhang H, Wang H. Identification of a Prognostic Model Based on NK Cell-Related Genes in Multiple Myeloma Using Single-Cell and Transcriptomic Data Analysis. Blood Lymphat Cancer 2024; 14:31-48. [PMID: 38854627 PMCID: PMC11162243 DOI: 10.2147/blctt.s461529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 05/21/2024] [Indexed: 06/11/2024]
Abstract
Background Multiple myeloma (MM), an incurable plasma cell malignancy. The significance of the relationship between natural killer (NK) cell-related genes and clinical factors in MM remains unclear. Methods Initially, we extracted NK cell-related genes from peripheral blood mononuclear cells (PBMC) of healthy donors and MM samples by employing single-cell transcriptome data analysis in TISCH2. Subsequently, we screened NK cell-related genes with prognostic significance through univariate Cox regression analysis and protein-protein interaction (PPI) network analysis. Following the initial analyses, we developed potential subtypes and prognostic models for MM using consensus clustering and lasso regression analysis. Additionally, we conducted a correlation analysis to explore the relationship between clinical features and risk scores. Finally, we constructed a weighted gene co-expression network analysis (WGCNA) and identified differentially expressed genes (DEGs) within the MM cohort. Results We discovered that 153 NK cell-related genes were significantly associated with the prognosisof MM patients (P <0.05). Patients in NK cluster A exhibited poorer survival outcomes compared to those in cluster B. Furthermore, our NK cell-related genes risk model revealed that patients with a high risk score had significantly worse prognoses (P <0.05). Patients with a high risk score were more likely to exhibit adverse clinical markers. Additionally, the nomogram based on NK cell-related genes demonstrated strong prognostic performance. The enrichment analysis indicated that immune-related pathways were significantly correlated with both the NK subtypes and the NK cell-related genes risk model. Ultimately, through the combined use of WGCNA and DEGs analysis, and by employing Venn diagrams, we determined that ITM2C is an independent prognostic marker for MM patients. Conclusion In this study, we developed a novel model based on NK cell-related genes to stratify the prognosis of MM patients. Notably, higher expression levels of ITM2C were associated with more favorable survival outcomes in these patients.
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Affiliation(s)
- Nan Mei
- Department of Hematology, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
| | - Sha Gong
- Department of Hematology, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
| | - Lizhao Wang
- Department of Breast Surgery, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
| | - Lu Wang
- Department of Hematology, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
| | - Jincheng Wang
- Department of Hematology, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
| | - Jianpeng Li
- Department of Urology, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
| | - Yingying Bao
- Institute of Gene and Cell Therapy, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
| | - Huanming Zhang
- Department of Hematology, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
| | - Huaiyu Wang
- Department of Hematology, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi Province, People’s Republic of China
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9
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Li D, Rocha-Roa C, Schilling MA, Reinisch KM, Vanni S. Lipid scrambling is a general feature of protein insertases. Proc Natl Acad Sci U S A 2024; 121:e2319476121. [PMID: 38621120 PMCID: PMC11047089 DOI: 10.1073/pnas.2319476121] [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: 11/07/2023] [Accepted: 03/13/2024] [Indexed: 04/17/2024] Open
Abstract
Glycerophospholipids are synthesized primarily in the cytosolic leaflet of the endoplasmic reticulum (ER) membrane and must be equilibrated between bilayer leaflets to allow the ER and membranes derived from it to grow. Lipid equilibration is facilitated by integral membrane proteins called "scramblases." These proteins feature a hydrophilic groove allowing the polar heads of lipids to traverse the hydrophobic membrane interior, similar to a credit card moving through a reader. Nevertheless, despite their fundamental role in membrane expansion and dynamics, the identity of most scramblases has remained elusive. Here, combining biochemical reconstitution and molecular dynamics simulations, we show that lipid scrambling is a general feature of protein insertases, integral membrane proteins which insert polypeptide chains into membranes of the ER and organelles disconnected from vesicle trafficking. Our data indicate that lipid scrambling occurs in the same hydrophilic channel through which protein insertion takes place and that scrambling is abolished in the presence of nascent polypeptide chains. We propose that protein insertases could have a so-far-overlooked role in membrane dynamics as scramblases.
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Affiliation(s)
- Dazhi Li
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
| | - Cristian Rocha-Roa
- Department of Biology, University of Fribourg, FribourgCH-1700, Switzerland
| | - Matthew A. Schilling
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
| | - Karin M. Reinisch
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT06520
| | - Stefano Vanni
- Department of Biology, University of Fribourg, FribourgCH-1700, Switzerland
- Swiss National Center for Competence in Research Bio-Inspired Materials, University of Fribourg, FribourgCH-1700, Switzerland
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10
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Zhu Q, Zhu X, Zhang L. ER membrane complex (EMC): Structure, functions, and roles in diseases. FASEB J 2024; 38:e23539. [PMID: 38498340 DOI: 10.1096/fj.202302266r] [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: 11/02/2023] [Revised: 01/22/2024] [Accepted: 02/21/2024] [Indexed: 03/20/2024]
Abstract
The endoplasmic reticulum (ER) is the largest membrane system in eukaryotic cells and is the primary site for the biosynthesis of lipids and carbohydrates, as well as for the folding, assembly, modification, and transport of secreted and integrated membrane proteins. The ER membrane complex (EMC) on the ER membrane is an ER multiprotein complex that affects the quality control of membrane proteins, which is abundant and widely preserved. Its disruption has been found to affect a wide range of processes, including protein and lipid synthesis, organelle communication, endoplasmic reticulum stress, and viral maturation, and may lead to neurodevelopmental disorders and cancer. Therefore, EMC has attracted the attention of many scholars and become a hot field. In this paper, we summarized the main contributions of the research of EMC in the past nearly 15 years, and reviewed the structure and function of EMC as well as its related diseases. We hope this review will promote further progress of research on EMC.
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Affiliation(s)
- Qi Zhu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Xianjun Zhu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
| | - Lin Zhang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan, China
- Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai, China
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11
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Qian ZY, Pan YQ, Li XX, Chen YX, Wu HX, Liu ZX, Kosar M, Bartek J, Wang ZX, Xu RH. Modulator of TMB-associated immune infiltration (MOTIF) predicts immunotherapy response and guides combination therapy. Sci Bull (Beijing) 2024; 69:803-822. [PMID: 38320897 DOI: 10.1016/j.scib.2024.01.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 11/04/2023] [Accepted: 12/07/2023] [Indexed: 02/08/2024]
Abstract
Patients with high tumor mutational burden (TMB) levels do not consistently respond to immune checkpoint inhibitors (ICIs), possibly because a high TMB level does not necessarily result in adequate infiltration of CD8+ T cells. Using bulk ribonucleic acid sequencing (RNA-seq) data from 9311 tumor samples across 30 cancer types, we developed a novel tool called the modulator of TMB-associated immune infiltration (MOTIF), which comprises genes that can determine the extent of CD8+ T cell infiltration prompted by a certain TMB level. We confirmed that MOTIF can accurately reflect the integrity and defects of the cancer-immunity cycle. By analyzing 84 human single-cell RNA-seq datasets from 32 types of solid tumors, we revealed that MOTIF can provide insights into the diverse roles of various cell types in the modulation of CD8+ T cell infiltration. Using pretreatment RNA-seq data from 13 ICI-treated cohorts, we validated the use of MOTIF in predicting CD8+ T cell infiltration and ICI efficacy. Among the components of MOTIF, we identified EMC3 as a negative regulator of CD8+ T cell infiltration, which was validated via in vivo studies. Additionally, MOTIF provided guidance for the potential combinations of programmed death 1 blockade with certain immunostimulatory drugs to facilitate CD8+ T cell infiltration and improve ICI efficacy.
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Affiliation(s)
- Zheng-Yu Qian
- Department of Medical Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Provincial Clinical Research Center for Cancer, Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, China
| | - Yi-Qian Pan
- Department of Medical Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Provincial Clinical Research Center for Cancer, Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, China
| | - Xue-Xin Li
- Science for Life Laboratory, Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm S-171 21, Sweden; Department of General Surgery, The Fourth Affiliated Hospital, China Medical University, Shenyang 110032, China
| | - Yan-Xing Chen
- Department of Medical Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Provincial Clinical Research Center for Cancer, Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, China
| | - Hao-Xiang Wu
- Department of Medical Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Provincial Clinical Research Center for Cancer, Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, China
| | - Ze-Xian Liu
- Department of Medical Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Provincial Clinical Research Center for Cancer, Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, China; Bioinformatics Platform, Sun Yat-sen University Cancer Center, Guangzhou 510060, China; Laboratory of Artificial Intelligence and Data Science, Sun Yat-sen University Cancer Center, Guangzhou 510060, China
| | - Martin Kosar
- Science for Life Laboratory, Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm S-171 21, Sweden; Zhejiang University-University of Edinburgh Institute, Zhejiang University School of Medicine, Haining 314400, China; Edinburgh Medical School, Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh EH1 1LT, UK
| | - Jiri Bartek
- Science for Life Laboratory, Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm S-171 21, Sweden; Danish Cancer Society Research Center, Copenhagen DK-2100, Denmark.
| | - Zi-Xian Wang
- Department of Medical Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Provincial Clinical Research Center for Cancer, Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, China; Laboratory of Artificial Intelligence and Data Science, Sun Yat-sen University Cancer Center, Guangzhou 510060, China.
| | - Rui-Hua Xu
- Department of Medical Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Provincial Clinical Research Center for Cancer, Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, China; Laboratory of Artificial Intelligence and Data Science, Sun Yat-sen University Cancer Center, Guangzhou 510060, China.
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12
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Li M, Zhang C, Xu Y, Li S, Huang C, Wu J, Lei M. Structural insights into human EMC and its interaction with VDAC. Aging (Albany NY) 2024; 16:5501-5525. [PMID: 38517390 PMCID: PMC11006472 DOI: 10.18632/aging.205660] [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: 11/06/2023] [Accepted: 02/08/2024] [Indexed: 03/23/2024]
Abstract
The endoplasmic reticulum (ER) membrane protein complex (EMC) is a conserved, multi-subunit complex acting as an insertase at the ER membrane. Growing evidence shows that the EMC is also involved in stabilizing and trafficking membrane proteins. However, the structural basis and regulation of its multifunctionality remain elusive. Here, we report cryo-electron microscopy structures of human EMC in apo- and voltage-dependent anion channel (VDAC)-bound states at resolutions of 3.47 Å and 3.32 Å, respectively. We discovered a specific interaction between VDAC proteins and the EMC at mitochondria-ER contact sites, which is conserved from yeast to humans. Moreover, we identified a gating plug located inside the EMC hydrophilic vestibule, the substrate-binding pocket for client insertion. Conformation changes of this gating plug during the apo-to-VDAC-bound transition reveal that the EMC unlikely acts as an insertase in the VDAC1-bound state. Based on the data analysis, the gating plug may regulate EMC functions by modifying the hydrophilic vestibule in different states. Our discovery offers valuable insights into the structural basis of EMC's multifunctionality.
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Affiliation(s)
- Mingyue Li
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
| | - Chunli Zhang
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
| | - Yuntao Xu
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
| | - Shaobai Li
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
| | - Chenhui Huang
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
| | - Jian Wu
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
| | - Ming Lei
- Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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13
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Sun K, Liu L, Jiang X, Wang H, Wang L, Yang Y, Liu W, Zhang L, Zhao X, Zhu X. The endoplasmic reticulum membrane protein complex subunit Emc6 is essential for rhodopsin localization and photoreceptor cell survival. Genes Dis 2024; 11:1035-1049. [PMID: 37692493 PMCID: PMC10492031 DOI: 10.1016/j.gendis.2023.03.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 02/17/2023] [Accepted: 03/29/2023] [Indexed: 09/12/2023] Open
Abstract
The endoplasmic reticulum (ER) membrane protein complex (EMC) is responsible for monitoring the biogenesis and synthetic quality of membrane proteins with tail-anchored or multiple transmembrane domains. The EMC subunit EMC6 is one of the core members of EMC and forms an enclosed hydrophilic vestibule in cooperation with EMC3. Despite studies demonstrating that deletion of EMC3 led to rhodopsin mislocalization in rod photoreceptors of mice, the precise mechanism leading to the failure of rhodopsin trafficking remains unclear. Here, we generated the first rod photoreceptor-specific knockout of Emc6 (RKO) and cone photoreceptor-specific knockout of Emc6 (CKO) mouse models. Deficiency of Emc6 in rod photoreceptors led to progressive shortening of outer segments (OS), impaired visual function, mislocalization and reduced expression of rhodopsin, and increased gliosis in rod photoreceptors. In addition, CKO mice displayed the progressive death of cone photoreceptors and abnormal localization of cone opsin protein. Subsequently, proteomics analysis of the RKO mouse retina illustrated that several cilium-related proteins, particularly anoctamin-2 (ANO2) and transmembrane protein 67 (TMEM67), were significantly down-regulated prior to OS degeneration. Detrimental rod photoreceptor cilia and mislocalized membrane disc proteins were evident in RKO mice. Our data revealed that in addition to monitoring the synthesis of rhodopsin-dominated membrane disc proteins, EMC6 also impacted rod photoreceptors' ciliogenesis by regulating the synthesis of membrane proteins associated with cilia, contributing to the mislocalization of membrane disc proteins.
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Affiliation(s)
- Kuanxiang Sun
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
- Key Laboratory of Tibetan Medicine Research, Chinese Academy of Sciences and Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Xining, Qinghai 810008, China
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan 610072, China
| | - Lu Liu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
| | - Xiaoyan Jiang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
| | - Heting Wang
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
| | - Lin Wang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
| | - Yeming Yang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
| | - Wenjing Liu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
| | - Lin Zhang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
| | - Xiaohui Zhao
- Key Laboratory of Tibetan Medicine Research, Chinese Academy of Sciences and Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Xining, Qinghai 810008, China
| | - Xianjun Zhu
- Health Management Center, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
- Key Laboratory of Tibetan Medicine Research, Chinese Academy of Sciences and Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Xining, Qinghai 810008, China
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan 610072, China
- Department of Ophthalmology, The First People's Hospital of Shangqiu, Shangqiu, Henan 476000, China
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14
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Gamerdinger M, Deuerling E. Cotranslational sorting and processing of newly synthesized proteins in eukaryotes. Trends Biochem Sci 2024; 49:105-118. [PMID: 37919225 DOI: 10.1016/j.tibs.2023.10.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/28/2023] [Accepted: 10/06/2023] [Indexed: 11/04/2023]
Abstract
Ribosomes interact with a variety of different protein biogenesis factors that guide newly synthesized proteins to their native 3D shapes and cellular localization. Depending on the type of translated substrate, a distinct set of cotranslational factors must interact with the ribosome in a timely and coordinated manner to ensure proper protein biogenesis. While cytonuclear proteins require cotranslational maturation and folding factors, secretory proteins must be maintained in an unfolded state and processed cotranslationally by transport and membrane translocation factors. Here we explore the specific cotranslational processing steps for cytonuclear, secretory, and membrane proteins in eukaryotes and then discuss how the nascent polypeptide-associated complex (NAC) cotranslationally sorts these proteins into the correct protein biogenesis pathway.
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Affiliation(s)
- Martin Gamerdinger
- Department of Biology, Molecular Microbiology, University of Konstanz, 78457 Konstanz, Germany.
| | - Elke Deuerling
- Department of Biology, Molecular Microbiology, University of Konstanz, 78457 Konstanz, Germany.
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15
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Zhou X, Xiao B, Jiang M, Rui J. Pan-cancer analysis identifies EMC6 as a potential target for lung adenocarcinoma. iScience 2024; 27:108648. [PMID: 38155776 PMCID: PMC10753071 DOI: 10.1016/j.isci.2023.108648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/14/2023] [Accepted: 12/04/2023] [Indexed: 12/30/2023] Open
Abstract
Endoplasmic reticulum membrane protein complex subunit 6 (EMC6) plays an important function in both physiological and pathological states of cells. Nevertheless, there are few studies focused on the role of EMC6 in tumors. At first, we performed a series of bioinformatics analyses on 33 kinds of cancers, including differential expression analysis, tumor mutational burden analysis, prognostic analysis, and clinicopathological staging analysis. Then, we corroborated the important role of EMC6 in lung cancer by cytological and in vivo experiments. We found that the reduction of EMC6 expression did effectively inhibit the proliferation, invasion, and metastasis of A549. Finally, EMC6 is indeed involved in the regulation of ferroptosis, cuproptosis, and immune response in LUAD. In a word, our study not only comprehensively analyzed the functional mechanisms of EMC6 in all cancers but also validated the regulatory role of EMC6 in lung cancer for the first time.
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Affiliation(s)
- Xin Zhou
- Department of Urology, The Wuxi No.2 People’s Hospital, Wuxi, China
| | - Bowen Xiao
- Department of Interventional Vascular Department, The Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China, Changsha, China
| | - Manman Jiang
- Suzhou Center for Disease Control, Suzhou, China
| | - Jun Rui
- Department of Chest, The Wuxi No.2 People’s Hospital, Wuxi, China
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16
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Wu H, Smalinskaitė L, Hegde RS. EMC rectifies the topology of multipass membrane proteins. Nat Struct Mol Biol 2024; 31:32-41. [PMID: 37957425 PMCID: PMC10803268 DOI: 10.1038/s41594-023-01120-6] [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: 04/25/2023] [Accepted: 09/08/2023] [Indexed: 11/15/2023]
Abstract
Most eukaryotic multipass membrane proteins are inserted into the membrane of the endoplasmic reticulum. Their transmembrane domains (TMDs) are thought to be inserted co-translationally as they emerge from a membrane-bound ribosome. Here we find that TMDs near the carboxyl terminus of mammalian multipass proteins are inserted post-translationally by the endoplasmic reticulum membrane protein complex (EMC). Site-specific crosslinking shows that the EMC's cytosol-facing hydrophilic vestibule is adjacent to a pre-translocated C-terminal tail. EMC-mediated insertion is mostly agnostic to TMD hydrophobicity, favored for short uncharged C-tails and stimulated by a preceding unassembled TMD bundle. Thus, multipass membrane proteins can be released by the ribosome-translocon complex in an incompletely inserted state, requiring a separate EMC-mediated post-translational insertion step to rectify their topology, complete biogenesis and evade quality control. This sequential co-translational and post-translational mechanism may apply to ~250 diverse multipass proteins, including subunits of the pentameric ion channel family that are crucial for neurotransmission.
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Affiliation(s)
- Haoxi Wu
- MRC Laboratory of Molecular Biology, Cambridge, UK
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17
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Shi L, Ma H, Wang J, Ma M, Zhao H, Li Z, Wang JH, Wu S, Zhou Z, Dong MQ, Li Z. An EMC-Hpo-Yki axis maintains intestinal homeostasis under physiological and pathological conditions. Development 2023; 150:dev201958. [PMID: 38031990 DOI: 10.1242/dev.201958] [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: 05/07/2023] [Accepted: 11/08/2023] [Indexed: 12/01/2023]
Abstract
Balanced control of stem cell proliferation and differentiation underlines tissue homeostasis. Disruption of tissue homeostasis often results in many diseases. However, how endogenous factors influence the proliferation and differentiation of intestinal stem cells (ISCs) under physiological and pathological conditions remains poorly understood. Here, we find that the evolutionarily conserved endoplasmic reticulum membrane protein complex (EMC) negatively regulates ISC proliferation and intestinal homeostasis. Compromising EMC function in progenitors leads to excessive ISC proliferation and intestinal homeostasis disruption. Mechanistically, the EMC associates with and stabilizes Hippo (Hpo) protein, the key component of the Hpo signaling pathway. In the absence of EMC, Yorkie (Yki) is activated to promote ISC proliferation due to Hpo destruction. The EMC-Hpo-Yki axis also functions in enterocytes to maintain intestinal homeostasis. Importantly, the levels of the EMC are dramatically diminished in tunicamycin-treated animals, leading to Hpo destruction, thereby resulting in intestinal homeostasis disruption due to Yki activation. Thus, our study uncovers the molecular mechanism underlying the action of the EMC in intestinal homeostasis maintenance under physiological and pathological conditions and provides new insight into the pathogenesis of tunicamycin-induced tumorigenesis.
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Affiliation(s)
- Lin Shi
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hubing Ma
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Jinjun Wang
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Meifang Ma
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hang Zhao
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhengran Li
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Jian-Hua Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Shian Wu
- College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zizhang Zhou
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing 102206, China
| | - Zhouhua Li
- Laboratory of Stem Cell Biology, College of Life Sciences, Capital Normal University, Beijing 100048, China
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18
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Zhou X, Yang Y, Wang G, Wang S, Sun D, Ou X, Lian Y, Li L. Molecular pathway of mitochondrial preprotein import through the TOM-TIM23 supercomplex. Nat Struct Mol Biol 2023; 30:1996-2008. [PMID: 37696957 DOI: 10.1038/s41594-023-01103-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 08/18/2023] [Indexed: 09/13/2023]
Abstract
Over half of mitochondrial proteins are imported from the cytosol via the pre-sequence pathway, controlled by the TOM complex in the outer membrane and the TIM23 complex in the inner membrane. The mechanisms through which proteins are translocated via the TOM and TIM23 complexes remain unclear. Here we report the assembly of the active TOM-TIM23 supercomplex of Saccharomyces cerevisiae with translocating polypeptide substrates. Electron cryo-microscopy analyses reveal that the polypeptide substrates pass the TOM complex through the center of a Tom40 subunit, interacting with a glutamine-rich region. Structural and biochemical analyses show that the TIM23 complex contains a heterotrimer of the subunits Tim23, Tim17 and Mgr2. The polypeptide substrates are shielded from lipids by Mgr2 and Tim17, which creates a translocation pathway characterized by a negatively charged entrance and a central hydrophobic region. These findings reveal an unexpected pre-sequence pathway through the TOM-TIM23 supercomplex spanning the double membranes of mitochondria.
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Affiliation(s)
- Xueyin Zhou
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Yuqi Yang
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Guopeng Wang
- School of Life Sciences, Peking University, Beijing, China
| | - Shanshan Wang
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Dongjie Sun
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Xiaomin Ou
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Yuke Lian
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Long Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
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19
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Page KR, Nguyen VN, Pleiner T, Tomaleri GP, Wang ML, Guna A, Wang TY, Chou TF, Voorhees RM. Role of a holo-insertase complex in the biogenesis of biophysically diverse ER membrane proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.28.569054. [PMID: 38076791 PMCID: PMC10705394 DOI: 10.1101/2023.11.28.569054] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
Mammalian membrane proteins perform essential physiologic functions that rely on their accurate insertion and folding at the endoplasmic reticulum (ER). Using forward and arrayed genetic screens, we systematically studied the biogenesis of a panel of membrane proteins, including several G-protein coupled receptors (GPCRs). We observed a central role for the insertase, the ER membrane protein complex (EMC), and developed a dual-guide approach to identify genetic modifiers of the EMC. We found that the back of sec61 (BOS) complex, a component of the 'multipass translocon', was a physical and genetic interactor of the EMC. Functional and structural analysis of the EMC•BOS holocomplex showed that characteristics of a GPCR's soluble domain determine its biogenesis pathway. In contrast to prevailing models, no single insertase handles all substrates. We instead propose a unifying model for coordination between the EMC, multipass translocon, and Sec61 for biogenesis of diverse membrane proteins in human cells.
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20
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Jung M, Zimmermann R. Quantitative Mass Spectrometry Characterizes Client Spectra of Components for Targeting of Membrane Proteins to and Their Insertion into the Membrane of the Human ER. Int J Mol Sci 2023; 24:14166. [PMID: 37762469 PMCID: PMC10532041 DOI: 10.3390/ijms241814166] [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: 08/09/2023] [Revised: 09/07/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
To elucidate the redundancy in the components for the targeting of membrane proteins to the endoplasmic reticulum (ER) and/or their insertion into the ER membrane under physiological conditions, we previously analyzed different human cells by label-free quantitative mass spectrometry. The HeLa and HEK293 cells had been depleted of a certain component by siRNA or CRISPR/Cas9 treatment or were deficient patient fibroblasts and compared to the respective control cells by differential protein abundance analysis. In addition to clients of the SRP and Sec61 complex, we identified membrane protein clients of components of the TRC/GET, SND, and PEX3 pathways for ER targeting, and Sec62, Sec63, TRAM1, and TRAP as putative auxiliary components of the Sec61 complex. Here, a comprehensive evaluation of these previously described differential protein abundance analyses, as well as similar analyses on the Sec61-co-operating EMC and the characteristics of the topogenic sequences of the various membrane protein clients, i.e., the client spectra of the components, are reported. As expected, the analysis characterized membrane protein precursors with cleavable amino-terminal signal peptides or amino-terminal transmembrane helices as predominant clients of SRP, as well as the Sec61 complex, while precursors with more central or even carboxy-terminal ones were found to dominate the client spectra of the SND and TRC/GET pathways for membrane targeting. For membrane protein insertion, the auxiliary Sec61 channel components indeed share the client spectra of the Sec61 complex to a large extent. However, we also detected some unexpected differences, particularly related to EMC, TRAP, and TRAM1. The possible mechanistic implications for membrane protein biogenesis at the human ER are discussed and can be expected to eventually advance our understanding of the mechanisms that are involved in the so-called Sec61-channelopathies, resulting from deficient ER protein import.
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Affiliation(s)
| | - Richard Zimmermann
- Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany;
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21
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Myronidi I, Ring A, Wu F, Ljungdahl PO. ER-localized Shr3 is a selective co-translational folding chaperone necessary for amino acid permease biogenesis. J Cell Biol 2023; 222:e202208060. [PMID: 37477900 PMCID: PMC10359922 DOI: 10.1083/jcb.202208060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 04/16/2023] [Accepted: 06/26/2023] [Indexed: 07/22/2023] Open
Abstract
Proteins with multiple membrane-spanning segments (MS) co-translationally insert into the endoplasmic reticulum (ER) membrane of eukaryotic cells. Shr3, an ER membrane-localized chaperone in Saccharomyces cerevisiae, is required for the functional expression of a family of 18 amino acid permeases (AAP) comprised of 12 MS. We have used comprehensive scanning mutagenesis and deletion analysis of Shr3 combined with a modified split-ubiquitin approach to probe chaperone-substrate interactions in vivo. Shr3 selectively interacts with nested C-terminal AAP truncations in marked contrast to similar truncations of non-Shr3 substrate sugar transporters. Shr3-AAP interactions initiate with the first four MS of AAP and successively strengthen but weaken abruptly when all 12 MS are present. Shr3-AAP interactions are based on structural rather than sequence-specific interactions involving membrane and luminal domains of Shr3. The data align with Shr3 engaging nascent N-terminal chains of AAP, functioning as a scaffold to facilitate folding as translation completes.
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Affiliation(s)
- Ioanna Myronidi
- Department of Molecular Biosciences, The Wenner-Gren Institute, SciLifeLab, Stockholm University, Stockholm, Sweden
| | - Andreas Ring
- Department of Molecular Biosciences, The Wenner-Gren Institute, SciLifeLab, Stockholm University, Stockholm, Sweden
| | - Fei Wu
- Department of Biochemistry and Biophysics, SciLifeLab, Stockholm University, Stockholm, Sweden
| | - Per O. Ljungdahl
- Department of Molecular Biosciences, The Wenner-Gren Institute, SciLifeLab, Stockholm University, Stockholm, Sweden
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22
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Li X, Jiang Z, Su Y, Wang K, Jiang X, Sun K, Yang Y, Zhou Y, Zhu X, Zhang L. Deletion of Emc1 in photoreceptor cells causes retinal degeneration in mice. FEBS J 2023; 290:4356-4370. [PMID: 37098815 DOI: 10.1111/febs.16807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/30/2023] [Accepted: 04/25/2023] [Indexed: 04/27/2023]
Abstract
The endoplasmic reticulum membrane protein complex (EMC) plays a critical role in the synthesis of multipass membrane proteins. Genetic studies indicated that mutations in EMC1 gene were associated with retinal degeneration diseases; however, the role of EMC1 in photoreceptor has not been confirmed. Here, we show that Emc1 ablation in the photoreceptor cells of mice recapitulated the retinitis pigmentosa phenotypes, including an attenuated scotopic electroretinogram response and the progressive degeneration of rod cells and cone cells. Histopathological examination of tissues from rod-specific Emc1 knockout mice revealed mislocalized rhodopsin and irregularly arranged cone cells at the age of 2 months. Further immunoblotting analysis revealed decreased levels of membrane proteins and endoplasmic reticulum chaperones in 1-month-old rod-specific Emc1 knockout mice retinae, and this led us to speculate that the loss of membrane proteins is the main cause of the degeneration of photoreceptors. EMC1 most likely regulated the membrane protein levels at an earlier step in the biosynthetic process before the proteins translocated into the endoplasmic reticulum. The present study demonstrates the essential roles of Emc1 in photoreceptor cells, and reveals the mechanism through which EMC1 mutations are linked to retinitis pigmentosa.
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Affiliation(s)
- Xiao Li
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Zhilin Jiang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Yujing Su
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Kaifang Wang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Xiaoyan Jiang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Kuanxiang Sun
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Yeming Yang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Yu Zhou
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Xianjun Zhu
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
- Key Laboratory of Tibetan Medicine Research, Chinese Academy of Sciences and Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Xining, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China
| | - Lin Zhang
- The Sichuan Provincial Key Laboratory for Human Disease Gene Study and Department of Laboratory Medicine, Center for Medical Genetics, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
- Key Laboratory of Tibetan Medicine Research, Chinese Academy of Sciences and Qinghai Provincial Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Xining, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, China
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23
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Marquez J, Aslam F, Khokha MK. Expanding EMC foldopathies: Topogenesis deficits alter the neural crest. Genesis 2023; 61:e23520. [PMID: 37318954 PMCID: PMC10524326 DOI: 10.1002/dvg.23520] [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: 06/23/2022] [Revised: 04/13/2023] [Accepted: 05/02/2023] [Indexed: 06/17/2023]
Abstract
The endoplasmic reticulum (ER) membrane protein complex (EMC) is essential for the insertion of a wide variety of transmembrane proteins into the plasma membrane across cell types. Each EMC is composed of Emc1-7, Emc10, and either Emc8 or Emc9. Recent human genetics studies have implicated variants in EMC genes as the basis for a group of human congenital diseases. The patient phenotypes are varied but appear to affect a subset of tissues more prominently than others. Namely, craniofacial development seems to be commonly affected. We previously developed an array of assays in Xenopus tropicalis to assess the effects of emc1 depletion on the neural crest, craniofacial cartilage, and neuromuscular function. We sought to extend this approach to additional EMC components identified in patients with congenital malformations. Through this approach, we determine that EMC9 and EMC10 are important for neural crest development and the development of craniofacial structures. The phenotypes observed in patients and our Xenopus model phenotypes similar to EMC1 loss of function likely due to a similar mechanism of dysfunction in transmembrane protein topogenesis.
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Affiliation(s)
- Jonathan Marquez
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Faiza Aslam
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Mustafa K. Khokha
- Pediatric Genomics Discovery Program, Department of Pediatrics and Genetics, Yale University School of Medicine, New Haven, CT, USA
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24
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Li D, Rocha-Roa C, Schilling MA, Reinisch KM, Vanni S. Lipid scrambling is a general feature of protein insertases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555937. [PMID: 37693532 PMCID: PMC10491306 DOI: 10.1101/2023.09.01.555937] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Glycerophospholipids are synthesized primarily in the cytosolic leaflet of the endoplasmic reticulum (ER) membrane and must be equilibrated between bilayer leaflets to allow the ER and membranes derived from it to grow. Lipid equilibration is facilitated by integral membrane proteins called "scramblases". These proteins feature a hydrophilic groove allowing the polar heads of lipids to traverse the hydrophobic membrane interior, similar to a credit-card moving through a reader. Nevertheless, despite their fundamental role in membrane expansion and dynamics, the identity of most scramblases has remained elusive. Here, combining biochemical reconstitution and molecular dynamics simulations, we show that lipid scrambling is a general feature of protein insertases, integral membrane proteins which insert polypeptide chains into membranes of the ER and organelles disconnected from vesicle trafficking. Our data indicate that lipid scrambling occurs in the same hydrophilic channel through which protein insertion takes place, and that scrambling is abolished in the presence of nascent polypeptide chains. We propose that protein insertases could have a so-far overlooked role in membrane dynamics as scramblases.
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Affiliation(s)
- Dazhi Li
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | | | - Matthew A. Schilling
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Karin M. Reinisch
- Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - Stefano Vanni
- Department of Biology, University of Fribourg, Switzerland
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25
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Li YP, Shen RJ, Cheng YM, Zhao Q, Jin K, Jin ZB, Zhang S. Exome sequencing in retinal dystrophy patients reveals a novel candidate gene ER membrane protein complex subunit 3. Heliyon 2023; 9:e20146. [PMID: 37809982 PMCID: PMC10559921 DOI: 10.1016/j.heliyon.2023.e20146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 09/05/2023] [Accepted: 09/13/2023] [Indexed: 10/10/2023] Open
Abstract
Inherited retinal dystrophies (IRDs) are a heterogeneous group of visual disorders caused by different pathogenic mutations in genes and regulatory sequences. The endoplasmic reticulum (ER) membrane protein complex (EMC) subunit 3 (EMC3) is the core unit of the EMC insertase that integrates the transmembrane peptides into lipid bilayers, and the function of its cytoplasmic carboxyl terminus remains to be elucidated. In this study, an insertional mutation c.768insT in the C-terminal coding region of EMC3 was identified and associated with dominant IRDs in a five-generation family. This mutation caused a frameshift in the coding sequence and a gain of an additional 16 amino acid residues (p.L256F-fs-ext21) to form a helix structure in the C-terminus of the EMC3 protein. The mutation is heterozygous with an incomplete penetrance, and cosegregates in all patients examined. This finding indicates that the C-terminus of EMC3 is essential for EMC functions and that EMC3 may be a novel candidate gene for retinal degenerative diseases.
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Affiliation(s)
- Yan-Ping Li
- Laboratory for Stem Cell & Retinal Regeneration, The Eye Hospital, Basic Medical College, Wenzhou Medical University, Wenzhou, 325027, China
| | - Ren-Juan Shen
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
| | - You-Min Cheng
- Laboratory for Stem Cell & Retinal Regeneration, The Eye Hospital, Basic Medical College, Wenzhou Medical University, Wenzhou, 325027, China
| | - Qingqing Zhao
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310030, China
| | - Kangxin Jin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Zi-Bing Jin
- Laboratory for Stem Cell & Retinal Regeneration, The Eye Hospital, Basic Medical College, Wenzhou Medical University, Wenzhou, 325027, China
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, 100730, China
| | - Shaodan Zhang
- The Eye Hospital of Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Glaucoma Research Institute of Wenzhou Medical University, Wenzhou, 325027, China
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26
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Pleiner T, Hazu M, Pinton Tomaleri G, Nguyen VN, Januszyk K, Voorhees RM. A selectivity filter in the ER membrane protein complex limits protein misinsertion at the ER. J Cell Biol 2023; 222:e202212007. [PMID: 37199759 PMCID: PMC10200711 DOI: 10.1083/jcb.202212007] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 03/31/2023] [Accepted: 04/20/2023] [Indexed: 05/19/2023] Open
Abstract
Tail-anchored (TA) proteins play essential roles in mammalian cells, and their accurate localization is critical for proteostasis. Biophysical similarities lead to mistargeting of mitochondrial TA proteins to the ER, where they are delivered to the insertase, the ER membrane protein complex (EMC). Leveraging an improved structural model of the human EMC, we used mutagenesis and site-specific crosslinking to map the path of a TA protein from its cytosolic capture by methionine-rich loops to its membrane insertion through a hydrophilic vestibule. Positively charged residues at the entrance to the vestibule function as a selectivity filter that uses charge-repulsion to reject mitochondrial TA proteins. Similarly, this selectivity filter retains the positively charged soluble domains of multipass substrates in the cytosol, thereby ensuring they adopt the correct topology and enforcing the "positive-inside" rule. Substrate discrimination by the EMC provides a biochemical explanation for one role of charge in TA protein sorting and protects compartment integrity by limiting protein misinsertion.
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Affiliation(s)
- Tino Pleiner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Masami Hazu
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Giovani Pinton Tomaleri
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Vy N. Nguyen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Kurt Januszyk
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Rebecca M. Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
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27
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Thangaratnarajah C, Nijland M, Borges-Araújo L, Jeucken A, Rheinberger J, Marrink SJ, Souza PCT, Paulino C, Slotboom DJ. Expulsion mechanism of the substrate-translocating subunit in ECF transporters. Nat Commun 2023; 14:4484. [PMID: 37491368 PMCID: PMC10368641 DOI: 10.1038/s41467-023-40266-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 07/20/2023] [Indexed: 07/27/2023] Open
Abstract
Energy-coupling factor (ECF)-type transporters mediate the uptake of micronutrients in many bacteria. They consist of a substrate-translocating subunit (S-component) and an ATP-hydrolysing motor (ECF module) Previous data indicate that the S-component topples within the membrane to alternately expose the binding site to either side of the membrane. In many ECF transporters, the substrate-free S-component can be expelled from the ECF module. Here we study this enigmatic expulsion step by cryogenic electron microscopy and reveal that ATP induces a concave-to-convex shape change of two long helices in the motor, thereby destroying the S-component's docking site and allowing for its dissociation. We show that adaptation of the membrane morphology to the conformational state of the motor may favour expulsion of the substrate-free S-component when ATP is bound and docking of the substrate-loaded S-component after hydrolysis. Our work provides a picture of bilayer-assisted chemo-mechanical coupling in the transport cycle of ECF transporters.
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Affiliation(s)
- Chancievan Thangaratnarajah
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Mark Nijland
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Luís Borges-Araújo
- Molecular Microbiology and Structural Biochemistry, CNRS and University of Lyon, 69367, Lyon, France
| | - Aike Jeucken
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Jan Rheinberger
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy Group, University of Groningen, 9747 AG, Groningen, The Netherlands
- Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany
| | - Siewert J Marrink
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Molecular Dynamics Group, University of Groningen, 9747 AG, Groningen, The Netherlands
| | - Paulo C T Souza
- Molecular Microbiology and Structural Biochemistry, CNRS and University of Lyon, 69367, Lyon, France
| | - Cristina Paulino
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands.
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy Group, University of Groningen, 9747 AG, Groningen, The Netherlands.
- Biochemistry Center, University of Heidelberg, Im Neuenheimer Feld 328, 69120, Heidelberg, Germany.
| | - Dirk J Slotboom
- Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Membrane Enzymology Group, University of Groningen, 9747 AG, Groningen, The Netherlands.
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28
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Abstract
Protein translocases, such as the bacterial SecY complex, the Sec61 complex of the endoplasmic reticulum (ER) and the mitochondrial translocases, facilitate the transport of proteins across membranes. In addition, they catalyze the insertion of integral membrane proteins into the lipid bilayer. Several membrane insertases cooperate with these translocases, thereby promoting the topogenesis, folding and assembly of membrane proteins. Oxa1 and BamA family members serve as core components in the two major classes of membrane insertases. They facilitate the integration of proteins with α-helical transmembrane domains and of β-barrel proteins into lipid bilayers, respectively. Members of the Oxa1 family were initially found in the internal membranes of bacteria, mitochondria and chloroplasts. Recent studies, however, also identified several Oxa1-type insertases in the ER, where they serve as catalytically active core subunits in the ER membrane protein complex (EMC), the guided entry of tail-anchored (GET) and the GET- and EMC-like (GEL) complex. The outer membrane of bacteria, mitochondria and chloroplasts contain β-barrel proteins, which are inserted by members of the BamA family. In this Cell Science at a Glance article and the accompanying poster, we provide an overview of these different types of membrane insertases and discuss their function.
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Affiliation(s)
- Büsra Kizmaz
- Cell Biology, University of Kaiserslautern, Kaiserslautern 67663, Germany
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29
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Chen Z, Mondal A, Abderemane-Ali F, Jang S, Niranjan S, Montaño JL, Zaro BW, Minor DL. EMC chaperone-Ca V structure reveals an ion channel assembly intermediate. Nature 2023; 619:410-419. [PMID: 37196677 PMCID: PMC10896479 DOI: 10.1038/s41586-023-06175-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 05/05/2023] [Indexed: 05/19/2023]
Abstract
Voltage-gated ion channels (VGICs) comprise multiple structural units, the assembly of which is required for function1,2. Structural understanding of how VGIC subunits assemble and whether chaperone proteins are required is lacking. High-voltage-activated calcium channels (CaVs)3,4 are paradigmatic multisubunit VGICs whose function and trafficking are powerfully shaped by interactions between pore-forming CaV1 or CaV2 CaVα1 (ref. 3), and the auxiliary CaVβ5 and CaVα2δ subunits6,7. Here we present cryo-electron microscopy structures of human brain and cardiac CaV1.2 bound with CaVβ3 to a chaperone-the endoplasmic reticulum membrane protein complex (EMC)8,9-and of the assembled CaV1.2-CaVβ3-CaVα2δ-1 channel. These structures provide a view of an EMC-client complex and define EMC sites-the transmembrane (TM) and cytoplasmic (Cyto) docks; interaction between these sites and the client channel causes partial extraction of a pore subunit and splays open the CaVα2δ-interaction site. The structures identify the CaVα2δ-binding site for gabapentinoid anti-pain and anti-anxiety drugs6, show that EMC and CaVα2δ interactions with the channel are mutually exclusive, and indicate that EMC-to-CaVα2δ hand-off involves a divalent ion-dependent step and CaV1.2 element ordering. Disruption of the EMC-CaV complex compromises CaV function, suggesting that the EMC functions as a channel holdase that facilitates channel assembly. Together, the structures reveal a CaV assembly intermediate and EMC client-binding sites that could have wide-ranging implications for the biogenesis of VGICs and other membrane proteins.
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Affiliation(s)
- Zhou Chen
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Abhisek Mondal
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Fayal Abderemane-Ali
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Seil Jang
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - Sangeeta Niranjan
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
| | - José L Montaño
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Balyn W Zaro
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Daniel L Minor
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA.
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA.
- California Institute for Quantitative Biomedical Research, University of California, San Francisco, CA, USA.
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA, USA.
- Molecular Biophysics and Integrated Bio-imaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA.
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30
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Chawla J, Goldowitz I, Oberstaller J, Zhang M, Pires CV, Navarro F, Sollelis L, Wang CCQ, Seyfang A, Dvorin J, Otto TD, Rayner JC, Marti M, Adams JH. Phenotypic Screens Identify Genetic Factors Associated with Gametocyte Development in the Human Malaria Parasite Plasmodium falciparum. Microbiol Spectr 2023; 11:e0416422. [PMID: 37154686 PMCID: PMC10269797 DOI: 10.1128/spectrum.04164-22] [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: 10/13/2022] [Accepted: 03/23/2023] [Indexed: 05/10/2023] Open
Abstract
Transmission of the deadly malaria parasite Plasmodium falciparum from humans to mosquitoes is achieved by specialized intraerythrocytic sexual forms called gametocytes. Though the crucial regulatory mechanisms leading to gametocyte commitment have recently come to light, networks of genes that control sexual development remain to be elucidated. Here, we report a pooled-mutant screen to identify genes associated with gametocyte development in P. falciparum. Our results categorized genes that modulate gametocyte progression as hypoproducers or hyperproducers of gametocytes, and the in-depth analysis of individual clones confirmed phenotypes in sexual commitment rates and putative functions in gametocyte development. We present a new set of genes that have not been implicated in gametocytogenesis before and demonstrate the potential of forward genetic screens in isolating genes impacting parasite sexual biology, an exciting step toward the discovery of new antimalarials for a globally significant pathogen. IMPORTANCE Blocking human-to-vector transmission is an essential step toward malaria elimination. Gametocytes are solely responsible for achieving this transmission and represent an opportunity for therapeutic intervention. While these falciform-shaped parasite stages were first discovered in the 1880s, our understanding of the genetic determinants responsible for their formation and molecular mechanisms that drive their development is limited. In this work, we developed a scalable screening methodology with piggyBac mutants to identify genes that influence the development of gametocytes in the most lethal human malaria parasite, P. falciparum. By doing so, we lay the foundation for large-scale functional genomic studies specifically designed to address remaining questions about sexual commitment, maturation, and mosquito infection in P. falciparum. Such functional genetic screens will serve to expedite the identification of essential pathways and processes for the development of novel transmission-blocking agents.
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Affiliation(s)
- Jyotsna Chawla
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Ilana Goldowitz
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, USA
| | - Jenna Oberstaller
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Min Zhang
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Camilla Valente Pires
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Francesca Navarro
- Boston Children’s Hospital and Harvard Medical School, Harvard Medical School, Boston, Massachusetts, USA
| | - Lauriane Sollelis
- Institute of Infection, Immunity, and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- Institute of Parasitology Zurich, VetSuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Chengqi C. Q. Wang
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Andreas Seyfang
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, USA
| | - Jeffrey Dvorin
- Boston Children’s Hospital and Harvard Medical School, Harvard Medical School, Boston, Massachusetts, USA
| | - Thomas D. Otto
- Institute of Infection, Immunity, and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Julian C. Rayner
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Matthias Marti
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, USA
- Institute of Infection, Immunity, and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- Institute of Parasitology Zurich, VetSuisse Faculty, University of Zurich, Zurich, Switzerland
| | - John H. Adams
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, Florida, USA
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31
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Shiota N, Shimokawa-Chiba N, Fujiwara K, Chiba S. Identification of Bacillus subtilis YidC substrates using a MifM-instructed translation arrest-based reporter. J Mol Biol 2023:168172. [PMID: 37290739 DOI: 10.1016/j.jmb.2023.168172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/26/2023] [Accepted: 05/31/2023] [Indexed: 06/10/2023]
Abstract
YidC is a member of the YidC/Oxa1/Alb3 protein family that is crucial for membrane protein biogenesis in the bacterial plasma membrane. While YidC facilitates the folding and complex assembly of membrane proteins along with the Sec translocon, it also functions as a Sec-independent membrane protein insertase in the YidC-only pathway. However, little is known about how membrane proteins are recognized and sorted by these pathways, especially in Gram-positive bacteria, for which only a small number of YidC substrates have been identified to date. In this study, we aimed to identify Bacillus subtilis membrane proteins whose membrane insertion depends on SpoIIIJ, the primary YidC homolog in B. subtilis. We took advantage of the translation arrest sequence of MifM, which can monitor YidC-dependent membrane insertion. Our systematic screening identified eight membrane proteins as candidate SpoIIIJ substrates. Results of our genetic study also suggest that the conserved arginine in the hydrophilic groove of SpoIIIJ is crucial for the membrane insertion of the substrates identified here. However, in contrast to MifM, a previously identified YidC substrate, the importance of the negatively charged residue on the substrates for membrane insertion varied depending on the substrate. These results suggest that B. subtilis YidC uses substrate-specific interactions to facilitate membrane insertion.
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Affiliation(s)
- Narumi Shiota
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555, Japan
| | - Naomi Shimokawa-Chiba
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555, Japan; Institute for Protein Dynamics, Kyoto Sangyo University, Japan
| | - Keigo Fujiwara
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555, Japan; Institute for Protein Dynamics, Kyoto Sangyo University, Japan
| | - Shinobu Chiba
- Faculty of Life Sciences, Kyoto Sangyo University, Motoyama, Kamigamo, Kita-Ku, Kyoto 603-8555, Japan; Institute for Protein Dynamics, Kyoto Sangyo University, Japan.
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32
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Liu N, Huang M, Liang X, Cao M, Lun Z, Zhang Y, Yang J, Bhadauria V, Zhao W, Yan J, Peng YL, Lu X. Magnaporthe oryzae endoplasmic reticulum membrane complex regulates the biogenesis of membrane proteins for pathogenicity. THE NEW PHYTOLOGIST 2023; 238:1163-1181. [PMID: 36772852 DOI: 10.1111/nph.18810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
In eukaryotes, the majority of newly synthesized integral membrane proteins are inserted into the endoplasmic reticulum (ER) membrane before transferred to their functional sites. The conserved ER membrane complex (EMC) takes part in the insertion process for tail-anchored membrane proteins. However, the function of EMC in phytopathogenic fungi has not been characterized. Here, we report the identification and functional characterization of two EMC subunits MoEmc5 and MoEmc2 in Magnaporthe oryzae. The knockout mutants ΔMoemc5 and ΔMoemc2 exhibit substantial defect in autophagy, pathogenicity, cell wall integrity, and magnesium ion sensitivity. We demonstrate that the autophagy process was severely impaired in the ΔMoemc5 and ΔMoemc2 mutants because of the low-protein steady-state level of Atg9, the sole membrane-associated autophagy protein. Furthermore, the protein level of membrane proteins Chs4, Fks1, and MoMnr2 is also significantly reduced in the ΔMoemc5 and ΔMoemc2 strains, leading to their supersensitivity to Calcofluor white, Congo red, and magnesium. In addition, MoEmc5, but not MoEmc2, acts as a magnesium transporter independent of its EMC function. Magnaporthe oryzae EMC regulates the biogenesis of membrane proteins for autophagy and virulence; therefore, EMC subunits could be potential targets for fungicide design in the future.
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Affiliation(s)
- Ning Liu
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
- Beijing Key Laboratory of Environment Friendly Management on Fruit Diseases and Pests in North China, Institute of Plant Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China
| | - Manna Huang
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Xinyuan Liang
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Miao Cao
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Zhiqin Lun
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Yan Zhang
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Jun Yang
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Vijai Bhadauria
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Wensheng Zhao
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Jiye Yan
- Beijing Key Laboratory of Environment Friendly Management on Fruit Diseases and Pests in North China, Institute of Plant Protection, Beijing Academy of Agriculture and Forestry Sciences, Beijing, 100097, China
| | - You-Liang Peng
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
| | - Xunli Lu
- State Key Laboratory of Agrobiotechnology and MOA Key Laboratory of Pest Monitoring and Green Management, China Agricultural University, Beijing, 100193, China
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33
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Bai L, Li H. Structural insights into the membrane chaperones for multi-pass membrane protein biogenesis. Curr Opin Struct Biol 2023; 79:102563. [PMID: 36863267 DOI: 10.1016/j.sbi.2023.102563] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 01/22/2023] [Accepted: 01/28/2023] [Indexed: 03/04/2023]
Abstract
Certain transmembrane α-helices of multi-pass membrane proteins line substrate transport paths or catalytic pockets and, therefore, are partially hydrophilic. Sec61 alone is insufficient to insert these less hydrophobic segments into the membrane and needs to work with dedicated membrane chaperones. Three such membrane chaperones have been described in the literature-the endoplasmic reticulum membrane protein complex (EMC), the TMCO1 complex, and the PAT complex. Recent structural studies on these membrane chaperones have revealed their overall architecture, multi-subunit assembly, putative substrate transmembrane helix-binding pockets, and cooperative mechanisms with the ribosome and Sec61 translocon. These structures are providing initial insights into the poorly understood processes of multi-pass membrane protein biogenesis.
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Affiliation(s)
- Lin Bai
- Department of Biochemistry and Biophysics, School of Basic Medical Sciences, Peking University, Beijing, 100083, China.
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, 49503, United States.
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34
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Wu H, Hegde RS. Mechanism of signal-anchor triage during early steps of membrane protein insertion. Mol Cell 2023; 83:961-973.e7. [PMID: 36764302 PMCID: PMC10155758 DOI: 10.1016/j.molcel.2023.01.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 12/08/2022] [Accepted: 01/18/2023] [Indexed: 02/11/2023]
Abstract
Most membrane proteins use their first transmembrane domain, known as a signal anchor (SA), for co-translational targeting to the endoplasmic reticulum (ER) via the signal recognition particle (SRP). The SA then inserts into the membrane using either the Sec61 translocation channel or the ER membrane protein complex (EMC) insertase. How EMC and Sec61 collaborate to ensure SA insertion in the correct topology is not understood. Using site-specific crosslinking, we detect a pre-insertion SA intermediate adjacent to EMC. This intermediate forms after SA release from SRP but before ribosome transfer to Sec61. The polypeptide's N-terminal tail samples a cytosolic vestibule bordered by EMC3, from where it can translocate across the membrane concomitant with SA insertion. The ribosome then docks on Sec61, which has an opportunity to insert those SAs skipped by EMC. These results suggest that EMC acts between SRP and Sec61 to triage SAs for insertion during membrane protein biogenesis.
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Affiliation(s)
- Haoxi Wu
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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35
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Fenech EJ, Cohen N, Kupervaser M, Gazi Z, Schuldiner M. A toolbox for systematic discovery of stable and transient protein interactors in baker's yeast. Mol Syst Biol 2023; 19:e11084. [PMID: 36651308 PMCID: PMC9912024 DOI: 10.15252/msb.202211084] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 01/19/2023] Open
Abstract
Identification of both stable and transient interactions is essential for understanding protein function and regulation. While assessing stable interactions is more straightforward, capturing transient ones is challenging. In recent years, sophisticated tools have emerged to improve transient interactor discovery, with many harnessing the power of evolved biotin ligases for proximity labelling. However, biotinylation-based methods have lagged behind in the model eukaryote, Saccharomyces cerevisiae, possibly due to the presence of several abundant, endogenously biotinylated proteins. In this study, we optimised robust biotin-ligation methodologies in yeast and increased their sensitivity by creating a bespoke technique for downregulating endogenous biotinylation, which we term ABOLISH (Auxin-induced BiOtin LIgase diminiSHing). We used the endoplasmic reticulum insertase complex (EMC) to demonstrate our approaches and uncover new substrates. To make these tools available for systematic probing of both stable and transient interactions, we generated five full-genome collections of strains in which every yeast protein is tagged with each of the tested biotinylation machineries, some on the background of the ABOLISH system. This comprehensive toolkit enables functional interactomics of the entire yeast proteome.
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Affiliation(s)
- Emma J Fenech
- Department of Molecular GeneticsWeizmann Institute of ScienceRehovotIsrael
| | - Nir Cohen
- Department of Molecular GeneticsWeizmann Institute of ScienceRehovotIsrael
| | - Meital Kupervaser
- The de Botton Protein Profiling Institute of the Nancy and Stephen Grand Israel National Centre for Personalized MedicineWeizmann Institute of ScienceRehovotIsrael
| | - Zohar Gazi
- Department of Molecular GeneticsWeizmann Institute of ScienceRehovotIsrael
| | - Maya Schuldiner
- Department of Molecular GeneticsWeizmann Institute of ScienceRehovotIsrael
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36
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Dalbey RE, Kaushik S, Kuhn A. YidC as a potential antibiotic target. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119403. [PMID: 36427551 DOI: 10.1016/j.bbamcr.2022.119403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 11/16/2022] [Accepted: 11/18/2022] [Indexed: 11/24/2022]
Abstract
The membrane insertase YidC, is an essential bacterial component and functions in the folding and insertion of many membrane proteins during their biogenesis. It is a multispanning protein in the inner (cytoplasmic) membrane of Escherichia coli that binds its substrates in the "greasy slide" through hydrophobic interaction. The hydrophilic part of the substrate transiently localizes in the groove of YidC before it is translocated into the periplasm. The groove, which is flanked by the greasy slide, is within the center of the membrane, and provides a promising target for inhibitors that would block the insertase function of YidC. In addition, since the greasy slide is available for the binding of various substrates, it could also provide a binding site for inhibitory molecules. In this review we discuss in detail the structure and the mechanism of how YidC interacts not only with its substrates, but also with its partner proteins, the SecYEG translocase and the SRP signal recognition particle. Insight into the substrate binding to the YidC catalytic groove is presented. We wind up the review with the idea that the hydrophilic groove would be a potential site for drug binding and the feasibility of YidC-targeted drug development.
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Affiliation(s)
- Ross E Dalbey
- Dept. of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, United States of America.
| | - Sharbani Kaushik
- Dept. of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, United States of America
| | - Andreas Kuhn
- Institute of Biology, University of Hohenheim, Stuttgart 70599, Germany.
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37
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Reconstitution of an N-AChR from Brugia malayi an evolved change in acetylcholine receptor accessory protein requirements in filarial parasites. PLoS Pathog 2022; 18:e1010962. [DOI: 10.1371/journal.ppat.1010962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 12/01/2022] [Accepted: 10/29/2022] [Indexed: 11/15/2022] Open
Abstract
Neurotransmission is an important target for anthelmintic drugs, where receptor characteristics and response can be examined through reconstitution ex vivo in Xenopus laevis oocytes. The homomeric ACR-16 nicotine sensitive acetylcholine receptors (N-AChRs) of several helminth species have been characterized in this way. Our efforts to reconstitute the N-AChR from the clade III filarial parasite, Brugia malayi using similar conditions, initially produced no detectable response. A robust response to acetylcholine is obtained from the closely related clade III parasite Ascaris suum, suggesting that specific changes have occurred between Ascaris and Brugia. N-AChRs from three species intermediate between A. suum and B. malayi were characterized to provide information on the cause. Maximal response to acetylcholine did not change abruptly, consistent with a discrete event, but rather decreased progressively from A. suum through Dracunculus medinensis, Gonglylonema pulchrum and Thelazia callipaeda. Receptor responses to the characteristic nicotine, and other agonists were generally similar. The decrease in maximal current did correlate with a delayed time to reach larger response. Together, this suggested that the failure to reconstitute the B. malayi N-AChR was one extreme of a progressive decrease and that an issue with synthesis of the receptor in oocytes was responsible. Addition of accessory proteins EMC-6, NRA-2 and NRA-4, in addition to RIC-3, produced a small, but measurable B. malayi N-AChR response. Pharmacological properties of a chimeric B. malayi N-AChR were equivalent to the other species, confirming the receptor response remains unchanged while its production is increasingly dependent on accessory proteins. One possibility is that loss of many subunits for acetylcholine receptors from the filarial nematode genome is linked to new subunit combinations that lead to such a dependence. This novel phylogenetic approach allowed the first characterization of a B. malayi AChR ex vivo and in doing so, provides a framework for the successful characterization of other receptors that have yet to be reconstituted.
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38
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O'Keefe S, Pool MR, High S. Membrane protein biogenesis at the ER: the highways and byways. FEBS J 2022; 289:6835-6862. [PMID: 33960686 DOI: 10.1111/febs.15905] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/19/2021] [Accepted: 04/28/2021] [Indexed: 01/13/2023]
Abstract
The Sec61 complex is the major protein translocation channel of the endoplasmic reticulum (ER), where it plays a central role in the biogenesis of membrane and secretory proteins. Whilst Sec61-mediated protein translocation is typically coupled to polypeptide synthesis, suggestive of significant complexity, an obvious characteristic of this core translocation machinery is its surprising simplicity. Over thirty years after its initial discovery, we now understand that the Sec61 complex is in fact the central piece of an elaborate jigsaw puzzle, which can be partly solved using new research findings. We propose that the Sec61 complex acts as a dynamic hub for co-translational protein translocation at the ER, proactively recruiting a range of accessory complexes that enhance and regulate its function in response to different protein clients. It is now clear that the Sec61 complex does not have a monopoly on co-translational insertion, with some transmembrane proteins preferentially utilising the ER membrane complex instead. We also have a better understanding of post-insertion events, where at least one membrane-embedded chaperone complex can capture the newly inserted transmembrane domains of multi-span proteins and co-ordinate their assembly into a native structure. Having discovered this array of Sec61-associated components and competitors, our next challenge is to understand how they act together in order to expand the range and complexity of the membrane proteins that can be synthesised at the ER. Furthermore, this diversity of components and pathways may open up new opportunities for targeted therapeutic interventions designed to selectively modulate protein biogenesis at the ER.
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Affiliation(s)
- Sarah O'Keefe
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK
| | - Martin R Pool
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK
| | - Stephen High
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK
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39
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Guna A, Stevens TA, Inglis AJ, Replogle JM, Esantsi TK, Muthukumar G, Shaffer KCL, Wang ML, Pogson AN, Jones JJ, Lomenick B, Chou TF, Weissman JS, Voorhees RM. MTCH2 is a mitochondrial outer membrane protein insertase. Science 2022; 378:317-322. [PMID: 36264797 PMCID: PMC9674023 DOI: 10.1126/science.add1856] [Citation(s) in RCA: 60] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the mitochondrial outer membrane, α-helical transmembrane proteins play critical roles in cytoplasmic-mitochondrial communication. Using genome-wide CRISPR screens, we identified MTCH2, and its paralog MTCH1, and showed that it is required for insertion of biophysically diverse tail-anchored (TA), signal-anchored, and multipass proteins, but not outer membrane β-barrel proteins. Purified MTCH2 was sufficient to mediate insertion into reconstituted proteoliposomes. Functional and mutational studies suggested that MTCH2 has evolved from a solute carrier transporter. MTCH2 uses membrane-embedded hydrophilic residues to function as a gatekeeper for the outer membrane, controlling mislocalization of TAs into the endoplasmic reticulum and modulating the sensitivity of leukemia cells to apoptosis. Our identification of MTCH2 as an insertase provided a mechanistic explanation for the diverse phenotypes and disease states associated with MTCH2 dysfunction. We showed that MTCH2 was both necessary and sufficient for insertion of diverse α-helical proteins into the mitochondrial outer membrane, and was the defining member of a family of insertases that have co-opted the SLC25 transporter fold.
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Affiliation(s)
- Alina Guna
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Taylor A Stevens
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Alison J Inglis
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Joseph M Replogle
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Medical Scientist Training Program, University of California, San Francisco, San Francisco, CA 94158, USA.,Tetrad Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Theodore K Esantsi
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Gayathri Muthukumar
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Kelly C L Shaffer
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Maxine L Wang
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Angela N Pogson
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Jeff J Jones
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Brett Lomenick
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Tsui-Fen Chou
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
| | - Jonathan S Weissman
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.,David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Rebecca M Voorhees
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Avenue, Pasadena, CA 91125, USA
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40
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Substrate-driven assembly of a translocon for multipass membrane proteins. Nature 2022; 611:167-172. [PMID: 36261522 PMCID: PMC9630114 DOI: 10.1038/s41586-022-05330-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 09/07/2022] [Indexed: 11/19/2022]
Abstract
Most membrane proteins are synthesized on endoplasmic reticulum (ER)-bound ribosomes docked at the translocon, a heterogeneous ensemble of transmembrane factors operating on the nascent chain1,2. How the translocon coordinates the actions of these factors to accommodate its different substrates is not well understood. Here we define the composition, function and assembly of a translocon specialized for multipass membrane protein biogenesis3. This ‘multipass translocon’ is distinguished by three components that selectively bind the ribosome–Sec61 complex during multipass protein synthesis: the GET- and EMC-like (GEL), protein associated with translocon (PAT) and back of Sec61 (BOS) complexes. Analysis of insertion intermediates reveals how features of the nascent chain trigger multipass translocon assembly. Reconstitution studies demonstrate a role for multipass translocon components in protein topogenesis, and cells lacking these components show reduced multipass protein stability. These results establish the mechanism by which nascent multipass proteins selectively recruit the multipass translocon to facilitate their biogenesis. More broadly, they define the ER translocon as a dynamic assembly whose subunit composition adjusts co-translationally to accommodate the biosynthetic needs of its diverse range of substrates. Biochemical reconstitution and functional analysis reveal how newly synthesized multipass membrane proteins dynamically remodel the translocon to facilitate their successful biogenesis.
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41
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Liu L, Mao S, Chen K, Dai J, Jin S, Chen L, Wang Y, Guo L, Yang Y, Zhan C, Xiong Z, Diao H, Zhou Y, Ding Q, Wang X. Membrane-Bound EMC10 Is Required for Sperm Motility via Maintaining the Homeostasis of Cytoplasm Sodium in Sperm. Int J Mol Sci 2022; 23:ijms231710069. [PMID: 36077468 PMCID: PMC9456234 DOI: 10.3390/ijms231710069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022] Open
Abstract
Endoplasmic reticulum membrane protein complex subunit 10 (EMC10) is an evolutionarily conserved and multifunctional factor across species. We previously reported that Emc10 knockout (KO) leads to mouse male infertility. Emc10-null spermatozoa exhibit multiple aspects of dysfunction, including reduced sperm motility. Two subunits of a Na/K-ATPase, ATP1A4 and ATP1B3, are nearly absent in Emc10 KO spermatozoa. Here, two isoforms of EMC10 were characterized in the mouse testis and epididymis: the membrane-bound (mEMC10) and secreted (scEMC10) isoforms. We present evidence that mEMC10, rather than scEMC10, is required for cytoplasm sodium homeostasis by positively regulating ATP1B3 expression in germ cells. Intra-testis mEMC10 overexpression rescued the sperm motility defect caused by Emc10 KO, while exogenous recombinant scEMC10 protein could not improve the motility of spermatozoa from either Emc10 KO mouse or asthenospermic subjects. Clinically, there is a positive association between ATP1B3 and EMC10 protein levels in human spermatozoa, whereas no correlation was proven between seminal plasma scEMC10 levels and sperm motility. These results highlight the important role of the membrane-bound EMC10 isoform in maintaining cytoplasm sodium homeostasis and sperm motility. Based on the present results, the mEMC10-Na, K/ATPase α4β3 axis is proposed as a novel mechanism underlying the regulation of cytoplasmic sodium and sperm motility, and its components seem to have therapeutic potential for asthenospermia.
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Affiliation(s)
- Lijie Liu
- Department of Urology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Shanhua Mao
- Department of Urology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Kuangyang Chen
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Jiarong Dai
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Shuoshuo Jin
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Lijiao Chen
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Yahao Wang
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Lina Guo
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute for Biomedical and Pharmaceutical Technologies), School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Yiting Yang
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute for Biomedical and Pharmaceutical Technologies), School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Chongwen Zhan
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Zuquan Xiong
- Department of Urology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Hua Diao
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute for Biomedical and Pharmaceutical Technologies), School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Yuchuan Zhou
- Shanghai Key Laboratory of Embryo Original Diseases, The International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200030, China
| | - Qiang Ding
- Department of Urology, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Xuanchun Wang
- Department of Endocrinology, Huashan Hospital, Fudan University, Shanghai 200040, China
- Correspondence: ; Tel.: +86-21-5288-8286
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42
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Whittsette AL, Wang YJ, Mu TW. The endoplasmic reticulum membrane complex promotes proteostasis of GABA A receptors. iScience 2022; 25:104754. [PMID: 35938049 PMCID: PMC9352529 DOI: 10.1016/j.isci.2022.104754] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 06/30/2022] [Accepted: 07/07/2022] [Indexed: 11/29/2022] Open
Abstract
The endoplasmic reticulum membrane complex (EMC) plays a critical role in the biogenesis of tail-anchored proteins and a subset of multi-pass membrane proteins in the endoplasmic reticulum (ER). However, because of nearly exclusive expression of neurotransmitter-gated ion channels in the central nervous system (CNS), the role of the EMC in their biogenesis is not well understood. In this study, we demonstrated that the EMC positively regulates the surface trafficking and thus function of endogenous γ-aminobutyric acid type A (GABAA) receptors, the primary inhibitory ion channels in the mammalian brain. Moreover, among ten EMC subunits, EMC3 and EMC6 have the most prominent effect, and overexpression of EMC3 or EMC6 is sufficient to restore the function of epilepsy-associated GABAA receptor variants. In addition, EMC3 and EMC6 demonstrate endogenous interactions with major neuroreceptors, which depends on their transmembrane domains, suggesting a general role of the EMC in the biogenesis of neuroreceptors.
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Affiliation(s)
- Angela L. Whittsette
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Ya-Juan Wang
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Ting-Wei Mu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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Sinning I, McDowell MA. Cryo-EM insights into tail-anchored membrane protein biogenesis in eukaryotes. Curr Opin Struct Biol 2022; 75:102428. [PMID: 35850079 DOI: 10.1016/j.sbi.2022.102428] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/10/2022] [Accepted: 06/16/2022] [Indexed: 11/03/2022]
Abstract
Tail-anchored (TA) proteins are a biologically significant class of membrane proteins, which require specialised cellular pathways to insert their single C-terminal transmembrane domain into the correct membrane. Cryo-electron microscopy has recently provided new insights into the organelle-specific machineries for TA protein biogenesis. Structures of targeting and insertase complexes within the canonical guided entry of TA proteins (GET) pathway indicate how substrates are faithfully chaperoned into the endoplasmic reticulum (ER) membrane in metazoans. The core of the GET insertase is conserved within structures of the ER membrane protein complex (EMC), which acts in parallel to insert a different subset of TA proteins. Furthermore, structures of the dislocases Spf1 and Msp1 show how they remove mislocalised TA proteins from the ER and outer mitochondrial membranes respectively.
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Affiliation(s)
- Irmgard Sinning
- Heidelberg University Biochemistry Center (BZH), Im Neuenheimer Feld 328, 69120 Heidelberg, Germany.
| | - Melanie A McDowell
- Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt Am Main, Germany.
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Lang S, Nguyen D, Bhadra P, Jung M, Helms V, Zimmermann R. Signal Peptide Features Determining the Substrate Specificities of Targeting and Translocation Components in Human ER Protein Import. Front Physiol 2022; 13:833540. [PMID: 35899032 PMCID: PMC9309488 DOI: 10.3389/fphys.2022.833540] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 05/17/2022] [Indexed: 12/11/2022] Open
Abstract
In human cells, approximately 30% of all polypeptides enter the secretory pathway at the level of the endoplasmic reticulum (ER). This process involves cleavable amino-terminal signal peptides (SPs) or more or less amino-terminal transmembrane helices (TMHs), which serve as targeting determinants, at the level of the precursor polypeptides and a multitude of cytosolic and ER proteins, which facilitate their ER import. Alone or in combination SPs and TMHs guarantee the initial ER targeting as well as the subsequent membrane integration or translocation. Cytosolic SRP and SR, its receptor in the ER membrane, mediate cotranslational targeting of most nascent precursor polypeptide chains to the polypeptide-conducting Sec61 complex in the ER membrane. Alternatively, fully-synthesized precursor polypeptides and certain nascent precursor polypeptides are targeted to the ER membrane by either the PEX-, SND-, or TRC-pathway. Although these targeting pathways may have overlapping functions, the question arises how relevant this is under cellular conditions and which features of SPs and precursor polypeptides determine preference for a certain pathway. Irrespective of their targeting pathway(s), most precursor polypeptides are integrated into or translocated across the ER membrane via the Sec61 channel. For some precursor polypeptides specific Sec61 interaction partners have to support the gating of the channel to the open state, again raising the question why and when this is the case. Recent progress shed light on the client spectrum and specificities of some auxiliary components, including Sec62/Sec63, TRAM1 protein, and TRAP. To address the question which precursors use a certain pathway or component in intact human cells, i.e., under conditions of fast translation rates and molecular crowding, in the presence of competing precursors, different targeting organelles, and relevant stoichiometries of the involved components, siRNA-mediated depletion of single targeting or transport components in HeLa cells was combined with label-free quantitative proteomics and differential protein abundance analysis. Here, we present a summary of the experimental approach as well as the resulting differential protein abundance analyses and discuss their mechanistic implications in light of the available structural data.
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Affiliation(s)
- Sven Lang
- Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Duy Nguyen
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Pratiti Bhadra
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Martin Jung
- Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Richard Zimmermann
- Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
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Khan S. Endoplasmic Reticulum in Metaplasticity: From Information Processing to Synaptic Proteostasis. Mol Neurobiol 2022; 59:5630-5655. [PMID: 35739409 DOI: 10.1007/s12035-022-02916-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 06/05/2022] [Indexed: 11/29/2022]
Abstract
The ER (endoplasmic reticulum) is a Ca2+ reservoir and the unique protein-synthesizing machinery which is distributed throughout the neuron and composed of multiple different structural domains. One such domain is called EMC (endoplasmic reticulum membrane protein complex), pleiotropic nature in cellular functions. The ER/EMC position inside the neurons unmasks its contribution to synaptic plasticity via regulating various cellular processes from protein synthesis to Ca2+ signaling. Since presynaptic Ca2+ channels and postsynaptic ionotropic receptors are organized into the nanodomains, thus ER can be a crucial player in establishing TMNCs (transsynaptic molecular nanocolumns) to shape efficient neural communications. This review hypothesized that ER is not only involved in stress-mediated neurodegeneration but also axon regrowth, remyelination, neurotransmitter switching, information processing, and regulation of pre- and post-synaptic functions. Thus ER might not only be a protein-synthesizing and quality control machinery but also orchestrates plasticity of plasticity (metaplasticity) within the neuron to execute higher-order brain functions and neural repair.
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Affiliation(s)
- Shumsuzzaman Khan
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH, USA.
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Vrijsen S, Vrancx C, Del Vecchio M, Swinnen JV, Agostinis P, Winderickx J, Vangheluwe P, Annaert W. Inter-organellar Communication in Parkinson's and Alzheimer's Disease: Looking Beyond Endoplasmic Reticulum-Mitochondria Contact Sites. Front Neurosci 2022; 16:900338. [PMID: 35801175 PMCID: PMC9253489 DOI: 10.3389/fnins.2022.900338] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 05/05/2022] [Indexed: 01/13/2023] Open
Abstract
Neurodegenerative diseases (NDs) are generally considered proteinopathies but whereas this may initiate disease in familial cases, onset in sporadic diseases may originate from a gradually disrupted organellar homeostasis. Herein, endolysosomal abnormalities, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and altered lipid metabolism are commonly observed in early preclinical stages of major NDs, including Parkinson's disease (PD) and Alzheimer's disease (AD). Among the multitude of underlying defective molecular mechanisms that have been suggested in the past decades, dysregulation of inter-organellar communication through the so-called membrane contact sites (MCSs) is becoming increasingly apparent. Although MCSs exist between almost every other type of subcellular organelle, to date, most focus has been put on defective communication between the ER and mitochondria in NDs, given these compartments are critical in neuronal survival. Contributions of other MCSs, notably those with endolysosomes and lipid droplets are emerging, supported as well by genetic studies, identifying genes functionally involved in lysosomal homeostasis. In this review, we summarize the molecular identity of the organelle interactome in yeast and mammalian cells, and critically evaluate the evidence supporting the contribution of disturbed MCSs to the general disrupted inter-organellar homeostasis in NDs, taking PD and AD as major examples.
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Affiliation(s)
- Stephanie Vrijsen
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, KU Leuven, Leuven, Belgium
| | - Céline Vrancx
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Mara Del Vecchio
- Laboratory of Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
| | - Johannes V. Swinnen
- Laboratory of Lipid Metabolism and Cancer, Department of Oncology, Leuven Cancer Institute (LKI), KU Leuven, Leuven, Belgium
| | - Patrizia Agostinis
- Laboratory of Cell Death Research and Therapy, VIB-Center for Cancer Research, KU Leuven, Leuven, Belgium
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Joris Winderickx
- Laboratory of Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, KU Leuven, Leuven, Belgium
| | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
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Zika virus infection accelerates Alzheimer’s disease phenotypes in brain organoids. Cell Death Dis 2022; 8:153. [PMID: 35368019 PMCID: PMC8976422 DOI: 10.1038/s41420-022-00958-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 02/23/2022] [Accepted: 03/16/2022] [Indexed: 12/17/2022]
Abstract
Alzheimer’s disease (AD) is one of the progressive neurodegenerative diseases characterized by β-amyloid (Aβ) production and Phosphorylated-Tau (p-Tau) protein in the cerebral cortex. The precise mechanisms of the cause, responsible for disease pathology and progression, are not well understood because there are multiple risk factors associated with the disease. Viral infection is one of the risk factors for AD, and we demonstrated that Zika virus (ZIKV) infection in brain organoids could trigger AD pathological features, including Aβ and p-Tau expression. AD-related phenotypes in brain organoids were upregulated via endoplasmic reticulum (ER) stress and unfolded protein response (UPR) after ZIKV infection in brain organoids. Under persistent ER stress, activated-double stranded RNA-dependent protein kinase-like ER-resident (PERK) triggered the phosphorylation of Eukaryotic initiation factor 2 (eIF2α) and then BACE, and GSK3α/β related to AD. Furthermore, we demonstrated that pharmacological inhibitors of PERK attenuated Aβ and p-Tau in brain organoids after ZIKV infection.
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Vögtle FN, Koch HG, Meisinger C. A common evolutionary origin reveals fundamental principles of protein insertases. PLoS Biol 2022; 20:e3001558. [PMID: 35235553 PMCID: PMC8890630 DOI: 10.1371/journal.pbio.3001558] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- F.-Nora Vögtle
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Network Aging Research, Heidelberg University, Heidelberg, Germany
- CIBSS—Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
- * E-mail: (F-NV); (H-GK); (CM)
| | - Hans-Georg Koch
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- * E-mail: (F-NV); (H-GK); (CM)
| | - Chris Meisinger
- CIBSS—Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
- * E-mail: (F-NV); (H-GK); (CM)
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Chung HL, Rump P, Lu D, Glassford MR, Mok JW, Fatih J, Basal A, Marcogliese PC, Kanca O, Rapp M, Fock JM, Kamsteeg EJ, Lupski JR, Larson A, Haninbal MC, Bellen H, Harel T. De novo variants in EMC1 lead to neurodevelopmental delay and cerebellar degeneration and affect glial function in Drosophila. Hum Mol Genet 2022; 31:3231-3244. [PMID: 35234901 PMCID: PMC9523557 DOI: 10.1093/hmg/ddac053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 02/22/2022] [Accepted: 02/23/2022] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The endoplasmic reticulum (ER)-membrane protein complex (EMC) is a multi-protein transmembrane complex composed of 10 subunits that functions as a membrane-protein chaperone. Variants in EMC1 lead to neurodevelopmental delay and cerebellar degeneration. Multiple families with biallelic variants have been published, yet to date, only a single report of a monoallelic variant has been described, and functional evidence is sparse. METHODS Exome sequencing was used to investigate the genetic cause underlying severe developmental delay in three unrelated children. EMC1 variants were modeled in Drosophila, using loss-of-function (LoF) and overexpression studies. Glial-specific and neuronal-specific assays were used to determine whether the dysfunction was specific to one cell type. RESULTS Exome sequencing identified de novo variants in EMC1 in three individuals affected by global developmental delay, hypotonia, seizures, visual impairment and cerebellar atrophy. All variants were located at Pro582 or Pro584. Drosophila studies indicated that imbalance of EMC1-either overexpression or knockdown-results in pupal lethality and suggest that the tested homologous variants are LoF alleles. In addition, glia-specific gene dosage, overexpression or knockdown, of EMC1 led to lethality, whereas neuron-specific alterations were tolerated. DISCUSSION We establish de novo monoallelic EMC1 variants as causative of a neurological disease trait by providing functional evidence in a Drosophila model. The identified variants failed to rescue the lethality of a null allele. Variations in dosage of the wild-type EMC1, specifically in glia, lead to pupal lethality, which we hypothesize results from the altered stoichiometry of the multi-subunit protein complex EMC.
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Affiliation(s)
- Hyung-Lok Chung
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Patrick Rump
- University of Groningen, University Medical Centre Groningen, Department of Genetics, Groningen 9700 RB, The Netherlands
| | - Di Lu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Megan R Glassford
- Division of Pediatric Genetics, Metabolism & Genomic Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Jung-Wan Mok
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Jawid Fatih
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Adily Basal
- Department of Genetics, Hadassah Medical Organization, Jerusalem 9112001, Israel
| | - Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Michele Rapp
- University of Colorado Anschutz Medical Campus, Aurora, CO 60045, USA
| | - Johanna M Fock
- University of Groningen, University Medical Centre Groningen, Department of Neurology, Groningen 9700 RB, The Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Centre, Nijmegen 6500 HB, The Netherlands
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA,Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA,Department of Pediatrics, Texas Children's Hospital, Houston, TX 77030, USA
| | - Austin Larson
- University of Colorado School of Medicine and Children's Hospital Colorado, Aurora, CO 60045, United States
| | - Mark C Haninbal
- Division of Pediatric Genetics, Metabolism & Genomic Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Hugo Bellen
- To whom correspondence should be addressed at: Department of Genetics, Hadassah-Hebrew University Medical Center, POB 12000, Jerusalem 9112001, Israel. Tel: +(972)-2-6776329; Fax: +(972)-2-6777618; ; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA. Tel: +1 832824-8750; Fax: +1832825-1240;
| | - Tamar Harel
- To whom correspondence should be addressed at: Department of Genetics, Hadassah-Hebrew University Medical Center, POB 12000, Jerusalem 9112001, Israel. Tel: +(972)-2-6776329; Fax: +(972)-2-6777618; ; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA. Tel: +1 832824-8750; Fax: +1832825-1240;
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Leznicki P, Schneider HO, Harvey JV, Shi WQ, High S. Co-translational biogenesis of lipid droplet integral membrane proteins. J Cell Sci 2022; 135:272279. [PMID: 34558621 PMCID: PMC8627552 DOI: 10.1242/jcs.259220] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 09/16/2021] [Indexed: 12/18/2022] Open
Abstract
Membrane proteins destined for lipid droplets (LDs), a major intracellular storage site for neutral lipids, are inserted into the endoplasmic reticulum (ER) and then trafficked to LDs where they reside in a hairpin loop conformation. Here, we show that LD membrane proteins can be delivered to the ER either co- or post-translationally and that their membrane-embedded region specifies pathway selection. The co-translational route for LD membrane protein biogenesis is insensitive to a small molecule inhibitor of the Sec61 translocon, Ipomoeassin F, and instead relies on the ER membrane protein complex (EMC) for membrane insertion. This route may even result in a transient exposure of the short N termini of some LD membrane proteins to the ER lumen, followed by putative topological rearrangements that would enable their transmembrane segment to form a hairpin loop and N termini to face the cytosol. Our study reveals an unexpected complexity to LD membrane protein biogenesis and identifies a role for the EMC during their co-translational insertion into the ER. Summary: Insertion of many lipid droplet membrane proteins into the ER is co-translational, mediated by the ER membrane protein complex and may involve topology reorientation.
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Affiliation(s)
- Pawel Leznicki
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
| | | | - Jada V Harvey
- Department of Chemistry, Ball State University, Muncie, IN 47306, USA
| | - Wei Q Shi
- Department of Chemistry, Ball State University, Muncie, IN 47306, USA
| | - Stephen High
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, M13 9PT, UK
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