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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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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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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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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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Woo TT, Williams JM, Tsai B. How host ER membrane chaperones and morphogenic proteins support virus infection. J Cell Sci 2023; 136:jcs261121. [PMID: 37401530 PMCID: PMC10357032 DOI: 10.1242/jcs.261121] [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] [Indexed: 07/05/2023] Open
Abstract
The multi-functional endoplasmic reticulum (ER) is exploited by viruses to cause infection. Morphologically, this organelle is a highly interconnected membranous network consisting of sheets and tubules whose levels are dynamic, changing in response to cellular conditions. Functionally, the ER is responsible for protein synthesis, folding, secretion and degradation, as well as Ca2+ homeostasis and lipid biosynthesis, with each event catalyzed by defined ER factors. Strikingly, these ER host factors are hijacked by viruses to support different infection steps, including entry, translation, replication, assembly and egress. Although the full repertoire of these ER factors that are hijacked is unknown, recent studies have uncovered several ER membrane machineries that are exploited by viruses - ranging from polyomavirus to flavivirus and coronavirus - to facilitate different steps of their life cycle. These discoveries should provide better understanding of virus infection mechanisms, potentially leading to the development of more effective anti-viral therapies.
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Affiliation(s)
- Tai-Ting Woo
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, BSRB 3043, Ann Arbor, MI 48109,USA
| | - Jeffrey M. Williams
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, BSRB 3043, Ann Arbor, MI 48109,USA
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, BSRB 3043, Ann Arbor, MI 48109,USA
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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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Moreira-Ramos S, Arias L, Flores R, Katz A, Levicán G, Orellana O. Synonymous mutations in the phosphoglycerate kinase 1 gene induce an altered response to protein misfolding in Schizosaccharomyces pombe. Front Microbiol 2023; 13:1074741. [PMID: 36713198 PMCID: PMC9875302 DOI: 10.3389/fmicb.2022.1074741] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 12/20/2022] [Indexed: 01/13/2023] Open
Abstract
Background Proteostasis refers to the processes that regulate the biogenesis, folding, trafficking, and degradation of proteins. Any alteration in these processes can lead to cell malfunction. Protein synthesis, a key proteostatic process, is highly-regulated at multiple levels to ensure adequate adaptation to environmental and physiological challenges such as different stressors, proteotoxic conditions and aging, among other factors. Because alterations in protein translation can lead to protein misfolding, examining how protein translation is regulated may also help to elucidate in part how proteostasis is controlled. Codon usage bias has been implicated in the fine-tuning of translation rate, as more-frequent codons might be read faster than their less-frequent counterparts. Thus, alterations in codon usage due to synonymous mutations may alter translation kinetics and thereby affect the folding of the nascent polypeptide, without altering its primary structure. To date, it has been difficult to predict the effect of synonymous mutations on protein folding and cellular fitness due to a scarcity of relevant data. Thus, the purpose of this work was to assess the effect of synonymous mutations in discrete regions of the gene that encodes the highly-expressed enzyme 3-phosphoglycerate kinase 1 (pgk1) in the fission yeast Schizosaccharomyces pombe. Results By means of systematic replacement of synonymous codons along pgk1, we found slightly-altered protein folding and activity in a region-specific manner. However, alterations in protein aggregation, heat stress as well as changes in proteasome activity occurred independently of the mutated region. Concomitantly, reduced mRNA levels of the chaperones Hsp9 and Hsp16 were observed. Conclusion Taken together, these data suggest that codon usage bias of the gene encoding this highly-expressed protein is an important regulator of protein function and proteostasis.
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Affiliation(s)
- Sandra Moreira-Ramos
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Loreto Arias
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Rodrigo Flores
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Assaf Katz
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Gloria Levicán
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile (USACH), Santiago, Chile
| | - Omar Orellana
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile,*Correspondence: Omar Orellana,
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8
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Tang X, Wei W, Snowball JM, Nakayasu ES, Bell SM, Ansong C, Lin X, Whitsett JA. EMC3 regulates mesenchymal cell survival via control of the mitotic spindle assembly. iScience 2022; 26:105667. [PMID: 36624844 PMCID: PMC9823123 DOI: 10.1016/j.isci.2022.105667] [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: 12/29/2021] [Revised: 08/15/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
Eukaryotic cells transit through the cell cycle to produce two daughter cells. Dysregulation of the cell cycle leads to cell death or tumorigenesis. Herein, we found a subunit of the ER membrane complex, EMC3, as a key regulator of cell cycle. Conditional deletion of Emc3 in mouse embryonic mesoderm led to reduced size and patterning defects of multiple organs. Emc3 deficiency impaired cell proliferation, causing spindle assembly defects, chromosome mis-segregation, cell cycle arrest at G2/M, and apoptosis. Upon entry into mitosis, mesenchymal cells upregulate EMC3 protein levels and localize EMC3 to the mitotic centrosomes. Further analysis indicated that EMC3 works together with VCP to tightly regulate the levels and activity of Aurora A, an essential factor for centrosome function and mitotic spindle assembly: while overexpression of EMC3 or VCP degraded Aurora A, their loss led to increased Aurora A stability but reduced Aurora A phosphorylation in mitosis.
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Affiliation(s)
- Xiaofang Tang
- Perinatal Institute, Divisions of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7029, Cincinnati, OH 45229, USA,Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, 2nd Nanjiang Rd, Nansha District, Guangzhou 511458, China
| | - Wei Wei
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, No. 2005 Songhu Rd, Shanghai 200438, China
| | - John M. Snowball
- Perinatal Institute, Divisions of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7029, Cincinnati, OH 45229, USA
| | - Ernesto S. Nakayasu
- Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99354, USA
| | - Sheila M. Bell
- Perinatal Institute, Divisions of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7029, Cincinnati, OH 45229, USA
| | - Charles Ansong
- Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99354, USA
| | - Xinhua Lin
- Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, 2nd Nanjiang Rd, Nansha District, Guangzhou 511458, China,State Key Laboratory of Genetic Engineering, School of Life Sciences, Zhongshan Hospital, Fudan University, No. 2005 Songhu Rd, Shanghai 200438, China,Corresponding author
| | - Jeffrey A. Whitsett
- Perinatal Institute, Divisions of Neonatology, Perinatal and Pulmonary Biology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 7029, Cincinnati, OH 45229, USA,Corresponding author
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9
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He MF, Liang JH, Shen YN, Zhang JW, Liu Y, Yang KY, Liu LC, Wang J, Xie Q, Hu C, Song X, Wang Y. Glycyrrhizin Inhibits SARS-CoV-2 Entry into Cells by Targeting ACE2. Life (Basel) 2022; 12:1706. [PMID: 36362861 PMCID: PMC9697465 DOI: 10.3390/life12111706] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 10/22/2022] [Accepted: 10/25/2022] [Indexed: 10/29/2023] Open
Abstract
Coronavirus Disease 2019 (COVID-19) is a highly infectious and pathogenic disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Early in this epidemic, the herbal formulas used in traditional Chinese medicine (TCM) were widely used for the treatment of COVID-19 in China. According to Venn diagram analysis, we found that Glycyrrhizae Radix et Rhizoma is a frequent herb in TCM formulas against COVID-19. The extract of Glycyrrhizae Radix et Rhizoma exhibits an anti-SARS-CoV-2 replication activity in vitro, but its pharmacological mechanism remains unclear. We here demonstrate that glycyrrhizin, the main active ingredient of Glycyrrhizae Radix et Rhizoma, prevents the coronavirus from entering cells by targeting angiotensin-converting enzyme 2 (ACE2). Glycyrrhizin inhibited the binding of the spike protein of the SARS-CoV-2 to ACE2 in our Western blot-based assay. The following bulk RNA-seq analysis showed that glycyrrhizin down-regulated ACE2 expression in vitro which was further confirmed by Western blot and quantitative PCR. Together, we believe that glycyrrhizin inhibits SARS-CoV-2 entry into cells by targeting ACE2.
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Affiliation(s)
- Ming-Feng He
- Foshan Hospital of Traditional Chinese Medicine, Foshan 528000, China
| | - Jian-Hui Liang
- Center for Translation Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Yan-Ni Shen
- Center for Translation Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Jin-Wen Zhang
- Center for Translation Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Ying Liu
- College of Pharmacy, Shenzhen Technology University, Shenzhen 518118, China
| | - Kuang-Yang Yang
- Foshan Hospital of Traditional Chinese Medicine, Foshan 528000, China
| | - Li-Chu Liu
- Foshan Hospital of Traditional Chinese Medicine, Foshan 528000, China
| | - Junyi Wang
- Bluewood Associates Co., Ltd., Suzhou 215134, China
| | - Qian Xie
- Center for Translation Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Chun Hu
- Key Laboratory of Structure-Based Drug Design & Discovery, Ministry of Education, School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Xun Song
- College of Pharmacy, Shenzhen Technology University, Shenzhen 518118, China
| | - Yan Wang
- Center for Translation Medicine Research and Development, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
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10
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Prognostic Signature Development on the Basis of Macrophage Phagocytosis-Mediated Oxidative Phosphorylation in Bladder Cancer. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:4754935. [PMID: 36211821 PMCID: PMC9537622 DOI: 10.1155/2022/4754935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 09/03/2022] [Accepted: 09/13/2022] [Indexed: 12/24/2022]
Abstract
Background Macrophages are correlated with the occurrence and progression of bladder cancer (BCa). However, few research has focused on the predictive relevance of macrophage phagocytosis-mediated oxidative phosphorylation (MPOP) with BCa overall survival. Herein, we aimed to propose the targeted macrophage control based on MPOP as a treatment method for BCa immunotherapy. Methods The mRNA expression data sets and clinical data of bladder cancer originated from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) data set. A systematic study of several GEO data sets found differentially expressed macrophage phagocytosis regulators (DE-MPR) between BCa and normal tissues. To discover overall survival-associated DE-MPR and develop prognostic gene signature with performance validated based on receiver operating curves and Kaplan-Meier curves, researchers used univariate and Lasso Cox regression analysis (ROC). External validation was done with GSE13057 and GSE69795. To clarify its molecular mechanism and immune relevance, GO/KEGG enrichment analysis and tumor immune analysis were used. To find independent bladder cancer prognostic variables, researchers employed multivariate Cox regression analysis. Finally, using TCGA data set, a predictive nomogram was built. Results In BCa, a four-gene signature of oxidative phosphorylation composed of PTPN6, IKZF3, HDLBP, and EMC1 was found to predict overall survival. With the MPOP feature, the ROC curve showed that TCGA data set and the external validation data set performed better in predicting overall survival than the traditional AJCC stage. The four-gene signature can identify cancers from normal tissue and separate patients into the high-risk and low-risk groups with different overall survival rates. The four MPOP-gene signature was an independent predictive factor for BCa. In predicting overall survival, a nomogram integrating genetic and clinical prognostic variables outperformed AJCC staging. Multiple oncological features and invasion-associated pathways were identified in the high-risk group, which were also correlated with significantly lower levels of immune cell infiltration. Conclusion This paper found the MPOP-feature gene and developed a predictive nomogram capable of accurately predicting bladder cancer overall survival. The above discoveries can contribute to the development of personalized treatments and medical decisions.
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11
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Bagchi P, Speckhart K, Kennedy A, Tai AW, Tsai B. A specific EMC subunit supports Dengue virus infection by promoting virus membrane fusion essential for cytosolic genome delivery. PLoS Pathog 2022; 18:e1010717. [PMID: 35834589 PMCID: PMC9321775 DOI: 10.1371/journal.ppat.1010717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Revised: 07/26/2022] [Accepted: 06/30/2022] [Indexed: 11/18/2022] Open
Abstract
Dengue virus (DENV) represents the most common human arboviral infection, yet its cellular entry mechanism remains unclear. The multi-subunit endoplasmic reticulum membrane complex (EMC) supports DENV infection, in part, by assisting the biosynthesis of viral proteins critical for downstream replication steps. Intriguingly, the EMC has also been shown to act at an earlier step prior to viral protein biogenesis, although this event is not well-defined. Here we demonstrate that the EMC subunit EMC4 promotes fusion of the DENV and endosomal membranes during entry, enabling delivery of the viral genome into the cytosol which is then targeted to the ER for viral protein biosynthesis. We also found that EMC4 mediates ER-to-endosome transfer of phosphatidylserine, a phospholipid whose presence in the endosome facilitates DENV-endosomal membrane fusion. These findings clarify the EMC-dependent DENV early entry step, suggesting a mechanism by which an ER-localized host factor can regulate viral fusion at the endosome.
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Affiliation(s)
- Parikshit Bagchi
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Kaitlyn Speckhart
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Andrew Kennedy
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Andrew W. Tai
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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12
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Pei D, Dalbey RE. Membrane Translocation of Folded Proteins. J Biol Chem 2022; 298:102107. [PMID: 35671825 PMCID: PMC9251779 DOI: 10.1016/j.jbc.2022.102107] [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: 02/05/2022] [Revised: 05/31/2022] [Accepted: 06/01/2022] [Indexed: 12/01/2022] Open
Abstract
An ever-increasing number of proteins have been shown to translocate across various membranes of bacterial as well as eukaryotic cells in their folded states as a part of physiological and/or pathophysiological processes. Herein we provide an overview of the systems/processes that are established or likely to involve the membrane translocation of folded proteins, such as protein export by the twin-arginine translocation (TAT) system in bacteria and chloroplasts, unconventional protein secretion (UPS) and protein import into the peroxisome in eukaryotes, and the cytosolic entry of proteins (e.g., bacterial toxins) and viruses into eukaryotes. We also discuss the various mechanistic models that have previously been proposed for the membrane translocation of folded proteins including pore/channel formation, local membrane disruption, membrane thinning, and transport by membrane vesicles. Finally, we introduce a newly discovered vesicular transport mechanism, vesicle budding and collapse (VBC), and present evidence that VBC may represent a unifying mechanism that drives some (and potentially all) of folded protein translocation processes.
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Affiliation(s)
- Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
| | - Ross E Dalbey
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12(th) Avenue, Columbus, OH 43210.
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13
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Gaspar CJ, Vieira LC, Santos CC, Christianson JC, Jakubec D, Strisovsky K, Adrain C, Domingos PM. EMC is required for biogenesis of Xport-A, an essential chaperone of Rhodopsin-1 and the TRP channel. EMBO Rep 2022; 23:e53210. [PMID: 34918864 PMCID: PMC8728618 DOI: 10.15252/embr.202153210] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 10/26/2021] [Accepted: 11/10/2021] [Indexed: 01/07/2023] Open
Abstract
The ER membrane protein complex (EMC) is required for the biogenesis of a subset of tail anchored (TA) and polytopic membrane proteins, including Rhodopsin-1 (Rh1) and the TRP channel. To understand the physiological implications of EMC-dependent membrane protein biogenesis, we perform a bioinformatic identification of Drosophila TA proteins. From 254 predicted TA proteins, screening in larval eye discs identified two proteins that require EMC for their biogenesis: fan and Xport-A. Fan is required for male fertility in Drosophila and we show that EMC is also required for this process. Xport-A is essential for the biogenesis of both Rh1 and TRP, raising the possibility that disruption of Rh1 and TRP biogenesis in EMC mutants is secondary to the Xport-A defect. We show that EMC is required for Xport-A TMD membrane insertion and that EMC-independent Xport-A mutants rescue Rh1 and TRP biogenesis in EMC mutants. Finally, our work also reveals a role for Xport-A in a glycosylation-dependent triage mechanism during Rh1 biogenesis in the endoplasmic reticulum.
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Affiliation(s)
- Catarina J Gaspar
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB‐NOVA)OeirasPortugal
- Membrane Traffic LabInstituto Gulbenkian de Ciência (IGC)OeirasPortugal
| | - Lígia C Vieira
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB‐NOVA)OeirasPortugal
- Present address:
Center for Genomics and Systems BiologyNew York University Abu DhabiAbu DhabiUnited Arab Emirates
| | - Cristiana C Santos
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB‐NOVA)OeirasPortugal
| | - John C Christianson
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal SciencesBotnar Research CentreUniversity of OxfordOxfordUK
| | - David Jakubec
- Institute of Organic Chemistry and BiochemistryCzech Academy of SciencesPragueCzech Republic
| | - Kvido Strisovsky
- Institute of Organic Chemistry and BiochemistryCzech Academy of SciencesPragueCzech Republic
| | - Colin Adrain
- Membrane Traffic LabInstituto Gulbenkian de Ciência (IGC)OeirasPortugal
- Patrick G Johnston Centre for Cancer ResearchQueen’s UniversityBelfastUK
| | - Pedro M Domingos
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB‐NOVA)OeirasPortugal
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14
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Cellular host factors for SARS-CoV-2 infection. Nat Microbiol 2021; 6:1219-1232. [PMID: 34471255 DOI: 10.1038/s41564-021-00958-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/03/2021] [Indexed: 02/07/2023]
Abstract
The coronavirus disease 2019 (COVID-19) pandemic has claimed millions of lives and caused a global economic crisis. No effective antiviral drugs are currently available to treat infections of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The medical need imposed by the pandemic has spurred unprecedented research efforts to study coronavirus biology. Every virus depends on cellular host factors and pathways for successful replication. These proviral host factors represent attractive targets for antiviral therapy as they are genetically more stable than viral targets and may be shared among related viruses. The application of various 'omics' technologies has led to the rapid discovery of proviral host factors that are required for the completion of the SARS-CoV-2 life cycle. In this Review, we summarize insights into the proviral host factors that are required for SARS-CoV-2 infection that were mainly obtained using functional genetic and interactome screens. We discuss cellular processes that are important for the SARS-CoV-2 life cycle, as well as parallels with non-coronaviruses. Finally, we highlight host factors that could be targeted by clinically approved molecules and molecules in clinical trials as potential antiviral therapies for COVID-19.
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15
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The ER membrane protein complex subunit Emc3 controls angiogenesis via the FZD4/WNT signaling axis. SCIENCE CHINA-LIFE SCIENCES 2021; 64:1868-1883. [PMID: 34128175 DOI: 10.1007/s11427-021-1941-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/29/2021] [Indexed: 02/08/2023]
Abstract
The endoplasmic reticulum (ER) membrane protein complex (EMC) regulates the synthesis and quality control of membrane proteins with multiple transmembrane domains. One of the membrane spanning subunits, EMC3, is a core member of the EMC complex that provides essential hydrophilic vestibule for substrate insertion. Here, we show that the EMC subunit Emc3 plays critical roles in the retinal vascular angiogenesis by regulating Norrin/Wnt signaling. Postnatal endothelial cell (EC)-specific deletion of Emc3 led to retarded retinal vascular development with a hyperpruned vascular network, the appearance of blunt-ended, aneurysm-like tip endothelial cells (ECs) with reduced numbers of filopodia and leakage of erythrocytes at the vascular front. Diminished tube formation and cell proliferation were also observed in EMC3 depleted human retinal endothelial cells (HRECs). We then discovered a critical role for EMC3 in expression of FZD4 receptor of β-catenin signaling using RNA sequencing, real-time quantitative PCR (RT-qPCR) and luciferase reporter assay. Moreover, augmentation of Wnt activity via lithium chloride (LiCl) treatment remarkably enhanced β-catenin signaling and cell proliferation of HRECs. Additionally, LiCl partially reversed the angiogenesis defects in Emc3-cKO mice. Our data reveal that Emc3 plays essential roles in angiogenesis through direct control of FZD4 expression and Norrin/β-catenin signaling.
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16
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How DNA and RNA Viruses Exploit Host Chaperones to Promote Infection. Viruses 2021; 13:v13060958. [PMID: 34064125 PMCID: PMC8224278 DOI: 10.3390/v13060958] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 12/18/2022] Open
Abstract
To initiate infection, a virus enters a host cell typically via receptor-dependent endocytosis. It then penetrates a subcellular membrane, reaching a destination that supports transcription, translation, and replication of the viral genome. These steps lead to assembly and morphogenesis of the new viral progeny. The mature virus finally exits the host cell to begin the next infection cycle. Strikingly, viruses hijack host molecular chaperones to accomplish these distinct entry steps. Here we highlight how DNA viruses, including polyomavirus and the human papillomavirus, exploit soluble and membrane-associated chaperones to enter a cell, penetrating and escaping an intracellular membrane en route for infection. We also describe the mechanism by which RNA viruses—including flavivirus and coronavirus—co-opt cytosolic and organelle-selective chaperones to promote viral endocytosis, protein biosynthesis, replication, and assembly. These examples underscore the importance of host chaperones during virus infection, potentially revealing novel antiviral strategies to combat virus-induced diseases.
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17
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Mayberry CL, Bond AC, Wilczek MP, Mehmood K, Maginnis MS. Sending mixed signals: polyomavirus entry and trafficking. Curr Opin Virol 2021; 47:95-105. [PMID: 33690104 DOI: 10.1016/j.coviro.2021.02.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/14/2021] [Accepted: 02/15/2021] [Indexed: 12/31/2022]
Abstract
Polyomaviruses are mostly non-pathogenic, yet some can cause human disease especially under conditions of immunosuppression, including JC, BK, and Merkel cell polyomaviruses. Direct interactions between viruses and the host early during infection dictate the outcome of disease, many of which remain enigmatic. However, significant work in recent years has contributed to our understanding of how this virus family establishes an infection, largely due to advances made for animal polyomaviruses murine and SV40. Here we summarize the major findings that have contributed to our understanding of polyomavirus entry, trafficking, disassembly, signaling, and immune evasion during the infectious process and highlight major unknowns in these processes that are open areas of study.
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Affiliation(s)
- Colleen L Mayberry
- Department of Molecular and Biomedical Sciences, The University of Maine, Orono, ME, USA
| | - Avery Cs Bond
- Department of Molecular and Biomedical Sciences, The University of Maine, Orono, ME, USA
| | - Michael P Wilczek
- Department of Molecular and Biomedical Sciences, The University of Maine, Orono, ME, USA
| | - Kashif Mehmood
- Department of Molecular and Biomedical Sciences, The University of Maine, Orono, ME, USA
| | - Melissa S Maginnis
- Department of Molecular and Biomedical Sciences, The University of Maine, Orono, ME, USA; Graduate School in Biomedical Sciences and Engineering, The University of Maine, Orono, ME, USA.
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18
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Phillips BP, Miller EA. Ribosome-associated quality control of membrane proteins at the endoplasmic reticulum. J Cell Sci 2020; 133:133/22/jcs251983. [PMID: 33247003 PMCID: PMC7116877 DOI: 10.1242/jcs.251983] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Protein synthesis is an energetically costly, complex and risky process. Aberrant protein biogenesis can result in cellular toxicity and disease, with membrane-embedded proteins being particularly challenging for the cell. In order to protect the cell from consequences of defects in membrane proteins, quality control systems act to maintain protein homeostasis. The majority of these pathways act post-translationally; however, recent evidence reveals that membrane proteins are also subject to co-translational quality control during their synthesis in the endoplasmic reticulum (ER). This newly identified quality control pathway employs components of the cytosolic ribosome-associated quality control (RQC) machinery but differs from canonical RQC in that it responds to biogenesis state of the substrate rather than mRNA aberrations. This ER-associated RQC (ER-RQC) is sensitive to membrane protein misfolding and malfunctions in the ER insertion machinery. In this Review, we discuss the advantages of co-translational quality control of membrane proteins, as well as potential mechanisms of substrate recognition and degradation. Finally, we discuss some outstanding questions concerning future studies of ER-RQC of membrane proteins.
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Affiliation(s)
- Ben P Phillips
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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19
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Miller-Vedam LE, Bräuning B, Popova KD, Schirle Oakdale NT, Bonnar JL, Prabu JR, Boydston EA, Sevillano N, Shurtleff MJ, Stroud RM, Craik CS, Schulman BA, Frost A, Weissman JS. Structural and mechanistic basis of the EMC-dependent biogenesis of distinct transmembrane clients. eLife 2020; 9:e62611. [PMID: 33236988 PMCID: PMC7785296 DOI: 10.7554/elife.62611] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022] Open
Abstract
Membrane protein biogenesis in the endoplasmic reticulum (ER) is complex and failure-prone. The ER membrane protein complex (EMC), comprising eight conserved subunits, has emerged as a central player in this process. Yet, we have limited understanding of how EMC enables insertion and integrity of diverse clients, from tail-anchored to polytopic transmembrane proteins. Here, yeast and human EMC cryo-EM structures reveal conserved intricate assemblies and human-specific features associated with pathologies. Structure-based functional studies distinguish between two separable EMC activities, as an insertase regulating tail-anchored protein levels and a broader role in polytopic membrane protein biogenesis. These depend on mechanistically coupled yet spatially distinct regions including two lipid-accessible membrane cavities which confer client-specific regulation, and a non-insertase EMC function mediated by the EMC lumenal domain. Our studies illuminate the structural and mechanistic basis of EMC's multifunctionality and point to its role in differentially regulating the biogenesis of distinct client protein classes.
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Affiliation(s)
- Lakshmi E Miller-Vedam
- Molecular, Cellular, and Computational Biophysics Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Bastian Bräuning
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Katerina D Popova
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Biomedical Sciences Graduate Program, University of California, San FranciscoSan FranciscoUnited States
| | - Nicole T Schirle Oakdale
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Jessica L Bonnar
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Jesuraj R Prabu
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Elizabeth A Boydston
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Natalia Sevillano
- Department of Pharmaceutical Chemistry, University of California, San FranciscoSan FranciscoUnited States
| | - Matthew J Shurtleff
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
| | - Robert M Stroud
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Charles S Craik
- Department of Pharmaceutical Chemistry, University of California, San FranciscoSan FranciscoUnited States
| | - Brenda A Schulman
- Department of Molecular Machines and Signaling, Max Planck Institute of BiochemistryMartinsriedGermany
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Jonathan S Weissman
- Department of Biology, Whitehead Institute, MITCambridgeUnited States
- Department of Cellular and Molecular Pharmacology, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical InstituteChevy ChaseUnited States
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20
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ER functions are exploited by viruses to support distinct stages of their life cycle. Biochem Soc Trans 2020; 48:2173-2184. [PMID: 33119046 DOI: 10.1042/bst20200395] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 09/29/2020] [Accepted: 10/05/2020] [Indexed: 02/07/2023]
Abstract
The endoplasmic reticulum (ER), with its expansive membranous system and a vast network of chaperones, enzymes, sensors, and ion channels, orchestrates diverse cellular functions, ranging from protein synthesis, folding, secretion, and degradation to lipid biogenesis and calcium homeostasis. Strikingly, some of the functions of the ER are exploited by viruses to promote their life cycles. During entry, viruses must penetrate a host membrane and reach an intracellular destination to express and replicate their genomes. These events lead to the assembly of new viral progenies that exit the host cell, thereby initiating further rounds of infection. In this review, we highlight how three distinct viruses - polyomavirus, flavivirus, and coronavirus - co-opt key functions of the ER to cause infection. We anticipate that illuminating this virus-ER interplay will provide rational therapeutic approaches to combat the virus-induced diseases.
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21
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Mayberry CL, Maginnis MS. Taking the Scenic Route: Polyomaviruses Utilize Multiple Pathways to Reach the Same Destination. Viruses 2020; 12:v12101168. [PMID: 33076363 PMCID: PMC7602598 DOI: 10.3390/v12101168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 10/08/2020] [Accepted: 10/09/2020] [Indexed: 01/02/2023] Open
Abstract
Members of the Polyomaviridae family differ in their host range, pathogenesis, and disease severity. To date, some of the most studied polyomaviruses include human JC, BK, and Merkel cell polyomavirus and non-human subspecies murine and simian virus 40 (SV40) polyomavirus. Although dichotomies in host range and pathogenesis exist, overlapping features of the infectious cycle illuminate the similarities within this virus family. Of particular interest to human health, JC, BK, and Merkel cell polyomavirus have all been linked to critical, often fatal, illnesses, emphasizing the importance of understanding the underlying viral infections that result in the onset of these diseases. As there are significant overlaps in the capacity of polyomaviruses to cause disease in their respective hosts, recent advancements in characterizing the infectious life cycle of non-human murine and SV40 polyomaviruses are key to understanding diseases caused by their human counterparts. This review focuses on the molecular mechanisms by which different polyomaviruses hijack cellular processes to attach to host cells, internalize, traffic within the cytoplasm, and disassemble within the endoplasmic reticulum (ER), prior to delivery to the nucleus for viral replication. Unraveling the fundamental processes that facilitate polyomavirus infection provides deeper insight into the conserved mechanisms of the infectious process shared within this virus family, while also highlighting critical unique viral features.
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Affiliation(s)
- Colleen L. Mayberry
- Department of Molecular and Biomedical Sciences, The University of Maine, Orono, ME 04469, USA;
| | - Melissa S. Maginnis
- Department of Molecular and Biomedical Sciences, The University of Maine, Orono, ME 04469, USA;
- Graduate School in Biomedical Sciences and Engineering, The University of Maine, Orono, ME 04469, USA
- Correspondence:
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22
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Tian S, Wu Q, Zhou B, Choi MY, Ding B, Yang W, Dong M. Proteomic Analysis Identifies Membrane Proteins Dependent on the ER Membrane Protein Complex. Cell Rep 2020; 28:2517-2526.e5. [PMID: 31484065 PMCID: PMC6749609 DOI: 10.1016/j.celrep.2019.08.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/18/2019] [Accepted: 07/30/2019] [Indexed: 02/04/2023] Open
Abstract
The endoplasmic reticulum (ER) membrane protein complex (EMC) is a key contributor to biogenesis and membrane integration of transmembrane proteins, but our understanding of its mechanisms and the range of EMC-dependent proteins remains incomplete. Here, we carried out an unbiased mass spectrometry (MS)-based quantitative proteomic analysis comparing membrane proteins in EMC-deficient cells to wild-type (WT) cells and identified 36 EMC-dependent membrane proteins and 171 EMC-independent membrane proteins. Of these, six EMC-dependent and six EMC-independent proteins were further independently validated. We found that a common feature among EMC-dependent proteins is that they contain transmembrane domains (TMDs) with polar and/or charged residues. Mutagenesis studies demonstrate that EMC dependency can be converted in cells by removing or introducing polar and/or charged residues within TMDs. Our studies expand the list of validated EMC-dependent and EMC-independent proteins and suggest that the EMC is involved in handling TMDs with residues challenging for membrane integration. The endoplasmic reticulum membrane protein complex (EMC) contributes to the biogenesis of transmembrane proteins. Using mass spectrometry-based quantitative proteomic analysis, Tian et al. identify EMC-dependent and EMC-independent proteins. The authors find evidence that the EMC is involved in handling transmembrane domains with polar and/or charged residues that are challenging for membrane integration.
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Affiliation(s)
- Songhai Tian
- Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Quan Wu
- Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Central Laboratory of Medical Research Centre, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, People's Republic of China
| | - Bo Zhou
- Division of Cancer Biology and Therapeutics, Departments of Surgery and Biomedical Sciences, Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Mei Yuk Choi
- Division of Genetics, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Bo Ding
- Bonacept LLC, San Diego, CA 92122, USA
| | - Wei Yang
- Division of Cancer Biology and Therapeutics, Departments of Surgery and Biomedical Sciences, Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Min Dong
- Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA.
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23
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Chen YJ, Williams JM, Arvan P, Tsai B. Reticulon protects the integrity of the ER membrane during ER escape of large macromolecular protein complexes. J Cell Biol 2020; 219:133556. [PMID: 31895406 PMCID: PMC7041682 DOI: 10.1083/jcb.201908182] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/28/2019] [Accepted: 11/24/2019] [Indexed: 02/08/2023] Open
Abstract
Escape of large macromolecular complexes from the endoplasmic reticulum (ER), such as a viral particle or cellular aggregate, likely induces mechanical stress initiated on the luminal side of the ER membrane, which may threaten its integrity. How the ER responds to this threat remains unknown. Here we demonstrate that the cytosolic leaflet ER morphogenic protein reticulon (RTN) protects ER membrane integrity when polyomavirus SV40 escapes the ER to reach the cytosol en route to infection. SV40 coopts an intrinsic RTN function, as we also found that RTN prevents membrane damage during ER escape of a misfolded proinsulin aggregate destined for lysosomal degradation via ER-phagy. Our studies reveal that although ER membrane integrity may be threatened during ER escape of large macromolecular protein complexes, the action of RTN counters this, presumably by deploying its curvature-inducing activity to provide membrane flexibility and stability to limit mechanical stress imposed on the ER membrane.
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Affiliation(s)
- Yu-Jie Chen
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Jeffrey M Williams
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Peter Arvan
- Division of Metabolism Endocrinology and Diabetes, Comprehensive Diabetes Center, University of Michigan Medical School, Ann Arbor, MI
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
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24
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The ER Membrane Protein Complex Promotes Biogenesis of Dengue and Zika Virus Non-structural Multi-pass Transmembrane Proteins to Support Infection. Cell Rep 2020; 27:1666-1674.e4. [PMID: 31067454 PMCID: PMC6521869 DOI: 10.1016/j.celrep.2019.04.051] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 03/05/2019] [Accepted: 04/09/2019] [Indexed: 01/01/2023] Open
Abstract
Although flaviviruses co-opt the function of the host endoplasmic reticulum (ER) membrane protein complex (EMC) during infection, a mechanistic explanation for this observation remains unclear. Here, we show that the EMC promotes biogenesis of dengue virus (DENV) and Zika virus (ZIKV) non-structural multi-pass transmembrane proteins NS4A and NS4B, which are necessary for viral replication. The EMC binds to NS4B and colocalizes with the DENV replication organelle. Mapping analysis reveals that the two N-terminal marginally hydrophobic domains of NS4B confer EMC dependency. Furthermore, altering the hydrophobicity of these two marginally hydrophobic domains relieves NS4B’s EMC dependency. We demonstrate that NS4B biogenesis, but not its stability, is reduced in EMC-depleted cells. Our data suggest that the EMC acts as a multi-pass transmembrane chaperone required for expression of at least two virally encoded proteins essential for flavivirus infection and point to a shared vulnerability during the viral life cycle that could be exploited for antiviral therapy. Multiple genetic screens have identified the ER membrane protein complex (EMC) as essential for infection by dengue and Zika flaviviruses. Lin et al. demonstrate that efficient biogenesis of the viral non-structural proteins NS4A and NS4B requires the EMC.
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25
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Bai L, You Q, Feng X, Kovach A, Li H. Structure of the ER membrane complex, a transmembrane-domain insertase. Nature 2020; 584:475-478. [PMID: 32494008 PMCID: PMC7442705 DOI: 10.1038/s41586-020-2389-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 04/07/2020] [Indexed: 11/24/2022]
Abstract
The ER membrane complex (EMC) cooperates with the Sec61 translocon to co-translationally insert a transmembrane helix (TMH) of many multi-pass integral membrane proteins into the ER membrane, and it is also responsible for inserting the TMH of some tail-anchored proteins 1–3. How EMC accomplishes this feat has been unclear. Here we report the first cryo-EM structure of the eukaryotic EMC. We found that the Saccharomyces cerevisiae EMC contains eight subunits (Emc1–6, 7, and 10); has a large lumenal region and a smaller cytosolic region; and has a transmembrane region formed by Emc4, 5, and 6 plus the transmembrane domains (TMDs) of Emc1 and 3. We identified a 5-TMH fold centered around Emc3 that resembles the prokaryotic insertase YidC and that delineates a largely hydrophilic client pocket. The TMD of Emc4 tilts away from the main transmembrane region of EMC and is partially mobile. Mutational studies demonstrated that Emc4 flexibility and the hydrophilicity of the client pocket are required for EMC function. The EMC structure reveals a remarkable evolutionary conservation with the prokaryotic insertases 4,5; suggests a similar mechanism of TMH insertion; and provides a framework for detailed understanding of membrane insertion for numerous eukaryotic integral membrane proteins and tail-anchored proteins.
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Affiliation(s)
- Lin Bai
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA.
| | - Qinglong You
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Xiang Feng
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Amanda Kovach
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA
| | - Huilin Li
- Structural Biology Program, Van Andel Institute, Grand Rapids, MI, USA.
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26
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Ubqln4 Facilitates Endoplasmic Reticulum-to-Cytosol Escape of a Nonenveloped Virus during Infection. J Virol 2020; 94:JVI.00103-20. [PMID: 32161173 DOI: 10.1128/jvi.00103-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 03/09/2020] [Indexed: 12/14/2022] Open
Abstract
The nonenveloped polyomavirus simian virus 40 (SV40) must penetrate the host endoplasmic reticulum (ER) membrane to enter the cytosol in order to promote infection. How this is accomplished is not entirely clear. Here, we demonstrate that the cytosolic chaperone Ubiquilin4 (Ubqln4) binds directly to the ER membrane J proteins B12 and B14. Strategically localized at the ER-cytosol interface, Ubqln4 captures SV40 emerging from the ER, thereby facilitating escape of the virus from the ER into the cytosol, which leads to infection. Strikingly, Ubqln4 engages the J proteins in a J-domain-independent manner, in contrast to the previously reported Hsc70-Hsp105-SGTA-Bag2 cytosolic complex that also mediates SV40 ER-to-cytosol transport. Our results also reveal that the H domain and STI1 motif (1-2) of Ubqln4 support J protein binding, essential for SV40 infection. Together, these data further clarify the molecular basis by which a nonenveloped virus escapes a host membrane during infectious entry.IMPORTANCE How a nonenveloped virus escapes from a host membrane to promote infection remains enigmatic. In the case of the nonenveloped polyomavirus SV40, penetration of the ER membrane to reach the cytosol is a decisive virus infection step. In this study, we found a new host factor called Ubqln4 that facilitates escape of SV40 from the ER into the cytosol, thereby providing a path for the virus to enter the nucleus to cause infection.
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27
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Volkmar N, Christianson JC. Squaring the EMC - how promoting membrane protein biogenesis impacts cellular functions and organismal homeostasis. J Cell Sci 2020; 133:133/8/jcs243519. [PMID: 32332093 PMCID: PMC7188443 DOI: 10.1242/jcs.243519] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Integral membrane proteins play key functional roles at organelles and the plasma membrane, necessitating their efficient and accurate biogenesis to ensure appropriate targeting and activity. The endoplasmic reticulum membrane protein complex (EMC) has recently emerged as an important eukaryotic complex for biogenesis of integral membrane proteins by promoting insertion and stability of atypical and sub-optimal transmembrane domains (TMDs). Although confirmed as a bona fide complex almost a decade ago, light is just now being shed on the mechanism and selectivity underlying the cellular responsibilities of the EMC. In this Review, we revisit the myriad of functions attributed the EMC through the lens of these new mechanistic insights, to address questions of the cellular and organismal roles the EMC has evolved to undertake. Summary: The EMC is an important factor facilitating membrane protein biogenesis. Here we discuss the broad cellular and organismal responsibilities overseen by client proteins requiring the EMC for maturation.
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Affiliation(s)
- Norbert Volkmar
- Jeffrey Cheah Biomedical Centre, Department of Medicine, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0XY, UK
| | - John C Christianson
- Oxford Centre for Translational Myeloma Research, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Botnar Research Centre, Headington, Oxford OX3 7LD, UK
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28
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Aviner R, Frydman J. Proteostasis in Viral Infection: Unfolding the Complex Virus-Chaperone Interplay. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a034090. [PMID: 30858229 DOI: 10.1101/cshperspect.a034090] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Viruses are obligate intracellular parasites that rely on their hosts for protein synthesis, genome replication, and viral particle production. As such, they have evolved mechanisms to divert host resources, including molecular chaperones, facilitate folding and assembly of viral proteins, stabilize complex structures under constant mutational pressure, and modulate signaling pathways to dampen antiviral responses and prevent premature host death. Biogenesis of viral proteins often presents unique challenges to the proteostasis network, as it requires the rapid and orchestrated production of high levels of a limited number of multifunctional, multidomain, and aggregation-prone proteins. To overcome such challenges, viruses interact with the folding machinery not only as clients but also as regulators of chaperone expression, function, and subcellular localization. In this review, we summarize the main types of interactions between viral proteins and chaperones during infection, examine evolutionary aspects of this relationship, and discuss the potential of using chaperone inhibitors as broad-spectrum antivirals.
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Affiliation(s)
- Ranen Aviner
- Department of Biology, Stanford University, Stanford, California 94305
| | - Judith Frydman
- Department of Biology, Stanford University, Stanford, California 94305.,Department of Genetics, Stanford University, Stanford, California 94305
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29
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Selective EMC subunits act as molecular tethers of intracellular organelles exploited during viral entry. Nat Commun 2020; 11:1127. [PMID: 32111841 PMCID: PMC7048770 DOI: 10.1038/s41467-020-14967-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 02/10/2020] [Indexed: 12/22/2022] Open
Abstract
Although viruses must navigate the complex host endomembrane system to infect cells, the strategies used to achieve this is unclear. During entry, polyomavirus SV40 is sorted from the late endosome (LE) to the endoplasmic reticulum (ER) to cause infection, yet how this is accomplished remains enigmatic. Here we find that EMC4 and EMC7, two ER membrane protein complex (EMC) subunits, support SV40 infection by promoting LE-to-ER targeting of the virus. They do this by engaging LE-associated Rab7, presumably to stabilize contact between the LE and ER. These EMC subunits also bind to the ER-resident fusion machinery component syntaxin18, which is required for SV40-arrival to the ER. Our data suggest that EMC4 and EMC7 act as molecular tethers, inter-connecting two intracellular compartments to enable efficient transport of a virus between these compartments. As LE-to-ER transport of cellular cargos is unclear, our results have broad implications for illuminating inter-organelle cargo transport. The endoplasmic reticulum membrane protein complex (EMC) is known to play a role in SV40 viral infection but precise mechanisms are unclear. Here, the authors report that the EMC acts as tether of late endosome–endoplasmic reticulum interorganellar membrane contact sites to promote SV40 viral infection.
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30
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Nasr ML. Large nanodiscs going viral. Curr Opin Struct Biol 2020; 60:150-156. [PMID: 32066086 PMCID: PMC10712563 DOI: 10.1016/j.sbi.2020.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 12/29/2022]
Abstract
Covalently circularized and DNA-corralled nanodisc technologies have enabled engineering of large-sized bilayer nanodiscs up to 90nm. These large nanodiscs have the potential to extend the applicability of nanodisc technology from studying small and medium-sized membrane proteins to acting as surrogate membranes to investigate functional and structural aspects of viral entry. Here, we discuss the recent technical developments leading to construction of large circularized and DNA-corralled nanodiscs and examine their application in viral entry.
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Affiliation(s)
- Mahmoud L Nasr
- Division of Renal Medicine, Division of Engineering in Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
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31
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Kane JR, Fong S, Shaul J, Frommlet A, Frank AO, Knapp M, Bussiere DE, Kim P, Ornelas E, Cuellar C, Hyrina A, Abend JR, Wartchow CA. A polyomavirus peptide binds to the capsid VP1 pore and has potent antiviral activity against BK and JC polyomaviruses. eLife 2020; 9:50722. [PMID: 31960795 PMCID: PMC6974358 DOI: 10.7554/elife.50722] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/30/2019] [Indexed: 12/18/2022] Open
Abstract
In pursuit of therapeutics for human polyomaviruses, we identified a peptide derived from the BK polyomavirus (BKV) minor structural proteins VP2/3 that is a potent inhibitor of BKV infection with no observable cellular toxicity. The thirteen-residue peptide binds to major structural protein VP1 with single-digit nanomolar affinity. Alanine-scanning of the peptide identified three key residues, substitution of each of which results in ~1000 fold loss of binding affinity with a concomitant reduction in antiviral activity. Structural studies demonstrate specific binding of the peptide to the pore of pentameric VP1. Cell-based assays demonstrate nanomolar inhibition (EC50) of BKV infection and suggest that the peptide acts early in the viral entry pathway. Homologous peptide exhibits similar binding to JC polyomavirus VP1 and inhibits infection with similar potency to BKV in a model cell line. Lastly, these studies validate targeting the VP1 pore as a novel strategy for the development of anti-polyomavirus agents.
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Affiliation(s)
- Joshua R Kane
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, United States.,Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Susan Fong
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Jacob Shaul
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Alexandra Frommlet
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Andreas O Frank
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Mark Knapp
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Dirksen E Bussiere
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Peter Kim
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Elizabeth Ornelas
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Carlos Cuellar
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Anastasia Hyrina
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Johanna R Abend
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, United States
| | - Charles A Wartchow
- Global Discovery Chemistry, Novartis Institutes for BioMedical Research, Emeryville, United States
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32
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Horníková L, Bruštíková K, Forstová J. Microtubules in Polyomavirus Infection. Viruses 2020; 12:E121. [PMID: 31963741 PMCID: PMC7019765 DOI: 10.3390/v12010121] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 12/12/2022] Open
Abstract
Microtubules, part of the cytoskeleton, are indispensable for intracellular movement, cell division, and maintaining cell shape and polarity. In addition, microtubules play an important role in viral infection. In this review, we summarize the role of the microtubules' network during polyomavirus infection. Polyomaviruses usurp microtubules and their motors to travel via early and late acidic endosomes to the endoplasmic reticulum. As shown for SV40, kinesin-1 and microtubules are engaged in the release of partially disassembled virus from the endoplasmic reticulum to the cytosol, and dynein apparently assists in the further disassembly of virions prior to their translocation to the cell nucleus-the place of their replication. Polyomavirus gene products affect the regulation of microtubule dynamics. Early T antigens destabilize microtubules and cause aberrant mitosis. The role of these activities in tumorigenesis has been documented. However, its importance for productive infection remains elusive. On the other hand, in the late phase of infection, the major capsid protein, VP1, of the mouse polyomavirus, counteracts T-antigen-induced destabilization. It physically binds microtubules and stabilizes them. The interaction results in the G2/M block of the cell cycle and prolonged S phase, which is apparently required for successful completion of the viral replication cycle.
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Affiliation(s)
| | | | - Jitka Forstová
- Department of Genetics and Microbiology, Faculty of Science, Charles University, BIOCEV, 25250 Vestec, Czech Republic; (L.H.); (K.B.)
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33
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Lakshminarayan R, Phillips BP, Binnian IL, Gomez-Navarro N, Escudero-Urquijo N, Warren AJ, Miller EA. Pre-emptive Quality Control of a Misfolded Membrane Protein by Ribosome-Driven Effects. Curr Biol 2020; 30:854-864.e5. [PMID: 31956032 PMCID: PMC7063571 DOI: 10.1016/j.cub.2019.12.060] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 12/02/2019] [Accepted: 12/19/2019] [Indexed: 12/13/2022]
Abstract
Cells possess multiple mechanisms that protect against the accumulation of toxic aggregation-prone proteins. Here, we identify a pre-emptive pathway that reduces synthesis of membrane proteins that have failed to properly assemble in the endoplasmic reticulum (ER). We show that loss of the ER membrane complex (EMC) or mutation of the Sec61 translocon causes reduced synthesis of misfolded forms of the yeast ABC transporter Yor1. Synthesis defects are rescued by various ribosomal mutations, as well as by reducing cellular ribosome abundance. Genetic and biochemical evidence point to a ribosome-associated quality-control pathway triggered by ribosome collisions when membrane domain insertion and/or folding fails. In support of this model, translation initiation also contributes to synthesis defects, likely by modulating ribosome abundance on the message. Examination of translation efficiency across the yeast membrane proteome revealed that polytopic membrane proteins have relatively low ribosome abundance, providing evidence for translational tuning to balance protein synthesis and folding. We propose that by modulating translation rates of poorly folded proteins, cells can pre-emptively protect themselves from potentially toxic aberrant transmembrane proteins. Yor1-ΔF shows synthesis defects when Sec61 or EMC function is compromised Synthesis defects are suppressed by ribosomal and RQC mutants Translation initiation is a second point of potential regulation Pre-emptive quality control on the ER might protect the cell from aberrant proteins
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Affiliation(s)
- Ramya Lakshminarayan
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Ave., New York, NY 10027, USA
| | - Ben P Phillips
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave., Cambridge CB2 0QH, UK
| | - Imogen L Binnian
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave., Cambridge CB2 0QH, UK
| | - Natalia Gomez-Navarro
- Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave., Cambridge CB2 0QH, UK
| | - Norberto Escudero-Urquijo
- Cambridge Institute for Medical Research, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Haematology, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Puddicomb Way, Cambridge CB2 0AW, UK
| | - Alan J Warren
- Cambridge Institute for Medical Research, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Department of Haematology, The Keith Peters Building, University of Cambridge, Hills Road, Cambridge CB2 0XY, UK; Wellcome Trust - Medical Research Council Stem Cell Institute, University of Cambridge, Puddicomb Way, Cambridge CB2 0AW, UK
| | - Elizabeth A Miller
- Department of Biological Sciences, Columbia University, 1212 Amsterdam Ave., New York, NY 10027, USA; Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Ave., Cambridge CB2 0QH, UK.
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34
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Chen YJ, Liu X, Tsai B. SV40 Hijacks Cellular Transport, Membrane Penetration, and Disassembly Machineries to Promote Infection. Viruses 2019; 11:v11100917. [PMID: 31590347 PMCID: PMC6832212 DOI: 10.3390/v11100917] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/23/2019] [Accepted: 09/23/2019] [Indexed: 12/22/2022] Open
Abstract
During entry, a virus must be transported through the endomembrane system of the host cell, penetrate a cellular membrane, and undergo capsid disassembly, to reach the cytosol and often the nucleus in order to cause infection. To do so requires the virus to coordinately exploit the action of cellular membrane transport, penetration, and disassembly machineries. How this is accomplished remains enigmatic for many viruses, especially for viruses belonging to the nonenveloped virus family. In this review, we present the current model describing infectious entry of the nonenveloped polyomavirus (PyV) SV40. Insights from SV40 entry are likely to provide strategies to combat PyV-induced diseases, and to illuminate cellular trafficking, membrane transport, and disassembly mechanisms.
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Affiliation(s)
- Yu-Jie Chen
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, BSRB 3043, Ann Arbor, MI 48109, USA.
| | - Xiaofang Liu
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, BSRB 3043, Ann Arbor, MI 48109, USA.
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, BSRB 3043, Ann Arbor, MI 48109, USA.
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35
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Hiramatsu N, Tago T, Satoh T, Satoh AK. ER membrane protein complex is required for the insertions of late-synthesized transmembrane helices of Rh1 in Drosophila photoreceptors. Mol Biol Cell 2019; 30:2890-2900. [PMID: 31553680 PMCID: PMC6822582 DOI: 10.1091/mbc.e19-08-0434] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Most membrane proteins are synthesized on and inserted into the membrane of the endoplasmic reticulum (ER), in eukaryote. The widely conserved ER membrane protein complex (EMC) facilitates the biogenesis of a wide range of membrane proteins. In this study, we investigated the EMC function using Drosophila photoreceptor as a model system. We found that the EMC was necessary only for the biogenesis of a subset of multipass membrane proteins such as rhodopsin (Rh1), TRP, TRPL, Csat, Cni, SERCA, and Na+K+ATPase α, but not for that of secretory or single-pass membrane proteins. Additionally, in EMC-deficient cells, Rh1 was translated to its C terminus but degraded independently from ER-associated degradation. Thus, EMC exerted its effect after translation but before or during the membrane integration of transmembrane domains (TMDs). Finally, we found that EMC was not required for the stable expression of the first three TMDs of Rh1 but was required for that of the fourth and fifth TMDs. Our results suggested that EMC is required for the ER membrane insertion of succeeding TMDs of multipass membrane proteins.
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Affiliation(s)
- Naoki Hiramatsu
- Program of Life and Environmental Sciences, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Tatsuya Tago
- Program of Life and Environmental Sciences, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Takunori Satoh
- Program of Life and Environmental Sciences, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Akiko K Satoh
- Program of Life and Environmental Sciences, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
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36
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Aiewsakun P, Simmonds P, Katzourakis A. The First Co-Opted Endogenous Foamy Viruses and the Evolutionary History of Reptilian Foamy Viruses. Viruses 2019; 11:v11070641. [PMID: 31336856 PMCID: PMC6669660 DOI: 10.3390/v11070641] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 12/17/2022] Open
Abstract
A recent study reported the discovery of an endogenous reptilian foamy virus (FV), termed ERV-Spuma-Spu, found in the genome of tuatara. Here, we report two novel reptilian foamy viruses also identified as endogenous FVs (EFVs) in the genomes of panther gecko (ERV-Spuma-Ppi) and Schlegel’s Japanese gecko (ERV-Spuma-Gja). Their presence indicates that FVs are capable of infecting reptiles in addition to mammals, amphibians, and fish. Numerous copies of full length ERV-Spuma-Spu elements were found in the tuatara genome littered with in-frame stop codons and transposable elements, suggesting that they are indeed endogenous and are not functional. ERV-Spuma-Ppi and ERV-Spuma-Gja, on the other hand, consist solely of a foamy virus-like env gene. Examination of host flanking sequences revealed that they are orthologous, and despite being more than 96 million years old, their env reading frames are fully coding competent with evidence for strong purifying selection to maintain expression and for them likely being transcriptionally active. These make them the oldest EFVs discovered thus far and the first documented EFVs that may have been co-opted for potential cellular functions. Phylogenetic analyses revealed a complex virus–host co-evolutionary history and cross-species transmission routes of ancient FVs.
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Affiliation(s)
- Pakorn Aiewsakun
- Department of Microbiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
| | - Peter Simmonds
- Nuffield Department of Medicine, University of Oxford, South Parks Road, Oxford OX1 3SY, UK
| | - Aris Katzourakis
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3SY, UK.
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37
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Abstract
Viruses must navigate the complex endomembranous network of the host cell to cause infection. In the case of a non-enveloped virus that lacks a surrounding lipid bilayer, endocytic uptake from the plasma membrane is not sufficient to cause infection. Instead, the virus must travel within organelle membranes to reach a specific cellular destination that supports exposure or arrival of the virus to the cytosol. This is achieved by viral penetration across a host endomembrane, ultimately enabling entry of the virus into the nucleus to initiate infection. In this review, we discuss the entry mechanisms of three distinct non-enveloped DNA viruses-adenovirus (AdV), human papillomavirus (HPV), and polyomavirus (PyV)-highlighting how each exploit different intracellular transport machineries and membrane penetration apparatus associated with the endosome, Golgi, and endoplasmic reticulum (ER) membrane systems to infect a host cell. These processes not only illuminate a highly-coordinated interplay between non-enveloped viruses and their host, but may provide new strategies to combat non-enveloped virus-induced diseases.
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Affiliation(s)
- Chelsey C Spriggs
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Mara C Harwood
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, United States; Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Billy Tsai
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, United States; Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, United States.
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38
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Xiong L, Zhang L, Yang Y, Li N, Lai W, Wang F, Zhu X, Wang T. ER complex proteins are required for rhodopsin biosynthesis and photoreceptor survival in Drosophila and mice. Cell Death Differ 2019; 27:646-661. [PMID: 31263175 PMCID: PMC7206144 DOI: 10.1038/s41418-019-0378-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 06/11/2019] [Accepted: 06/13/2019] [Indexed: 12/17/2022] Open
Abstract
Defective rhodopsin homeostasis is one of the major causes of retinal degeneration, including the disease Retinitis pigmentosa. To identify cellular factors required for the biosynthesis of rhodopsin, we performed a genome-wide genetic screen in Drosophila for mutants with reduced levels of rhodopsin. We isolated loss-of-function alleles in endoplasmic reticulum membrane protein complex 3 (emc3), emc5, and emc6, each of which exhibited defective phototransduction and photoreceptor cell degeneration. EMC3, EMC5, and EMC6 were essential for rhodopsin synthesis independent of the ER associated degradation (ERAD) pathway, which eliminates misfolded proteins. We generated null mutations for all EMC subunits, and further demonstrated that different EMC subunits play roles in different cellular functions. Conditional knockout of the Emc3 gene in mice led to mislocalization of rhodopsin protein and death of cone and rod photoreceptor cells. These data indicate conserved roles for EMC subunits in maintaining rhodopsin homeostasis and photoreceptor function, and suggest that retinal degeneration may also be caused by defects in early biosynthesis of rhodopsin.
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Affiliation(s)
- Liangyao Xiong
- Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, School of Life Sciences, Peking University, Beijing, 100871, China.,National Institute of Biological Sciences, Beijing, 102206, China
| | - Lin Zhang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610072, China
| | - Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610072, China
| | - Na Li
- Southwest Jiaotong University, Chengdu, Sichuan, China
| | - Wenjia Lai
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Fengchao Wang
- National Institute of Biological Sciences, Beijing, 102206, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, 100871, China
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610072, China. .,Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China. .,Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, China. .,Department of Ophthalmology, First People's Hospital of Shangqiu, Shangqiu, Henan, China.
| | - Tao Wang
- National Institute of Biological Sciences, Beijing, 102206, China. .,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, 100871, China.
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39
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Chitwood PJ, Hegde RS. The Role of EMC during Membrane Protein Biogenesis. Trends Cell Biol 2019; 29:371-384. [PMID: 30826214 DOI: 10.1016/j.tcb.2019.01.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 01/27/2019] [Accepted: 01/28/2019] [Indexed: 12/11/2022]
Abstract
Ten years ago, high-throughput genetic interaction analyses revealed an abundant and widely conserved protein complex residing in the endoplasmic reticulum (ER) membrane. Dubbed the ER membrane protein complex (EMC), its disruption has since been found to affect wide-ranging processes, including protein trafficking, organelle communication, ER stress, viral maturation, lipid homeostasis, and others. However, its molecular function has remained enigmatic. Recent studies suggest a role for EMC during membrane protein biogenesis. Biochemical reconstitution experiments show that EMC can directly mediate the insertion of transmembrane domains (TMDs) into the lipid bilayer. Given the large proportion of genes encoding membrane proteins, a central role for EMC as a TMD insertion factor can explain its high abundance, wide conservation, and pleiotropic phenotypes.
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Affiliation(s)
- Patrick J Chitwood
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB20QH, UK
| | - Ramanujan S Hegde
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB20QH, UK.
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40
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Coelho JPL, Stahl M, Bloemeke N, Meighen-Berger K, Alvira CP, Zhang ZR, Sieber SA, Feige MJ. A network of chaperones prevents and detects failures in membrane protein lipid bilayer integration. Nat Commun 2019; 10:672. [PMID: 30737405 PMCID: PMC6368539 DOI: 10.1038/s41467-019-08632-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/22/2019] [Indexed: 12/20/2022] Open
Abstract
A fundamental step in membrane protein biogenesis is their integration into the lipid bilayer with a defined orientation of each transmembrane segment. Despite this, it remains unclear how cells detect and handle failures in this process. Here we show that single point mutations in the membrane protein connexin 32 (Cx32), which cause Charcot-Marie-Tooth disease, can cause failures in membrane integration. This leads to Cx32 transport defects and rapid degradation. Our data show that multiple chaperones detect and remedy this aberrant behavior: the ER-membrane complex (EMC) aids in membrane integration of low-hydrophobicity transmembrane segments. If they fail to integrate, these are recognized by the ER-lumenal chaperone BiP. Ultimately, the E3 ligase gp78 ubiquitinates Cx32 proteins, targeting them for degradation. Thus, cells use a coordinated system of chaperones for the complex task of membrane protein biogenesis, which can be compromised by single point mutations, causing human disease.
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Affiliation(s)
- João P L Coelho
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Matthias Stahl
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
- SciLifeLab, Department of Oncology-Pathology, Karolinska Institutet, Box 1031, 171 21 Solna, Stockholm, Sweden
| | - Nicolas Bloemeke
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Kevin Meighen-Berger
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Carlos Piedrafita Alvira
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Zai-Rong Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 201210, China
| | - Stephan A Sieber
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany
| | - Matthias J Feige
- Center for Integrated Protein Science at the Department of Chemistry, Technical University of Munich, Lichtenbergstr. 4, 85748, Garching, Germany.
- Institute for Advanced Study, Technical University of Munich, Lichtenbergstr. 2a, 85748, Garching, Germany.
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41
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Volkmar N, Thezenas ML, Louie SM, Juszkiewicz S, Nomura DK, Hegde RS, Kessler BM, Christianson JC. The ER membrane protein complex promotes biogenesis of sterol-related enzymes maintaining cholesterol homeostasis. J Cell Sci 2019; 132:jcs.223453. [PMID: 30578317 PMCID: PMC6362398 DOI: 10.1242/jcs.223453] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 12/03/2018] [Indexed: 12/24/2022] Open
Abstract
The eukaryotic endoplasmic reticulum (ER) membrane contains essential complexes that oversee protein biogenesis and lipid metabolism, impacting nearly all aspects of cell physiology. The ER membrane protein complex (EMC) is a newly described transmembrane domain (TMD) insertase linked with various phenotypes, but whose clients and cellular responsibilities remain incompletely understood. We report that EMC deficiency limits the cellular boundaries defining cholesterol tolerance, reflected by diminished viability with limiting or excessive extracellular cholesterol. Lipidomic and proteomic analyses revealed defective biogenesis and concomitant loss of the TMD-containing ER-resident enzymes sterol-O-acyltransferase 1 (SOAT1) and squalene synthase (SQS, also known as FDFT1), which serve strategic roles in the adaptation of cells to changes in cholesterol availability. Insertion of the weakly hydrophobic tail-anchor (TA) of SQS into the ER membrane by the EMC ensures sufficient flux through the sterol biosynthetic pathway while biogenesis of polytopic SOAT1 promoted by the EMC provides cells with the ability to store free cholesterol as inert cholesteryl esters. By facilitating insertion of TMDs that permit essential mammalian sterol-regulating enzymes to mature accurately, the EMC is an important biogenic determinant of cellular robustness to fluctuations in cholesterol availability. This article has an associated First Person interview with the first author of the paper. Highlighted Article: The ER membrane protein complex promotes biogenesis of key membrane-bound enzymes responsible for regulation of cholesterol biosynthesis and storage, an important determinant of mammalian cell viability.
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Affiliation(s)
- Norbert Volkmar
- Ludwig Institute for Cancer Research, University of Oxford, ORCRB, Headington, Oxford, OX3 7DQ, UK
| | - Maria-Laetitia Thezenas
- Target Discovery Institute (TDI) Mass Spectrometry Laboratory, Nuffield Department of Medicine, University of Oxford, Headington, Oxford, OX3 7DQ, UK
| | - Sharon M Louie
- Dept. of Chemistry, Molecular and Cell Biology, and Nutritional Sciences and Toxicology, University of California-Berkeley, Berkeley, CA, 94720, USA
| | - Szymon Juszkiewicz
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Daniel K Nomura
- Dept. of Chemistry, Molecular and Cell Biology, and Nutritional Sciences and Toxicology, University of California-Berkeley, Berkeley, CA, 94720, USA
| | - Ramanujan S Hegde
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Benedikt M Kessler
- Target Discovery Institute (TDI) Mass Spectrometry Laboratory, Nuffield Department of Medicine, University of Oxford, Headington, Oxford, OX3 7DQ, UK
| | - John C Christianson
- Ludwig Institute for Cancer Research, University of Oxford, ORCRB, Headington, Oxford, OX3 7DQ, UK .,Oxford Centre for Translational Myeloma Research, NDORMS, University of Oxford, Botnar Research Centre, Headington, Oxford, OX3 7LD, UK
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42
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Shurtleff MJ, Itzhak DN, Hussmann JA, Schirle Oakdale NT, Costa EA, Jonikas M, Weibezahn J, Popova KD, Jan CH, Sinitcyn P, Vembar SS, Hernandez H, Cox J, Burlingame AL, Brodsky JL, Frost A, Borner GH, Weissman JS. The ER membrane protein complex interacts cotranslationally to enable biogenesis of multipass membrane proteins. eLife 2018; 7:37018. [PMID: 29809151 PMCID: PMC5995541 DOI: 10.7554/elife.37018] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 05/26/2018] [Indexed: 12/20/2022] Open
Abstract
The endoplasmic reticulum (ER) supports biosynthesis of proteins with diverse transmembrane domain (TMD) lengths and hydrophobicity. Features in transmembrane domains such as charged residues in ion channels are often functionally important, but could pose a challenge during cotranslational membrane insertion and folding. Our systematic proteomic approaches in both yeast and human cells revealed that the ER membrane protein complex (EMC) binds to and promotes the biogenesis of a range of multipass transmembrane proteins, with a particular enrichment for transporters. Proximity-specific ribosome profiling demonstrates that the EMC engages clients cotranslationally and immediately following clusters of TMDs enriched for charged residues. The EMC can remain associated after completion of translation, which both protects clients from premature degradation and allows recruitment of substrate-specific and general chaperones. Thus, the EMC broadly enables the biogenesis of multipass transmembrane proteins containing destabilizing features, thereby mitigating the trade-off between function and stability.
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Affiliation(s)
- Matthew J Shurtleff
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Daniel N Itzhak
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jeffrey A Hussmann
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Nicole T Schirle Oakdale
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Elizabeth A Costa
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Martin Jonikas
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Jimena Weibezahn
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Katerina D Popova
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Calvin H Jan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Pavel Sinitcyn
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Shruthi S Vembar
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Hilda Hernandez
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States
| | - Jürgen Cox
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States.,Chan Zuckerberg Biohub, San Francisco, United States
| | - Georg Hh Borner
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States.,Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
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43
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Wang X, Xia Y, Xu C, Lin X, Xue P, Zhu S, Bai Y, Chen Y. ER membrane protein complex subunit 6 (EMC6) is a novel tumor suppressor in gastric cancer. BMB Rep 2018. [PMID: 28648145 PMCID: PMC5595170 DOI: 10.5483/bmbrep.2017.50.8.065] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The endoplasmic reticulum (ER) membrane protein complex subunit 6 (EMC6) is a novel human autophagy-related molecule. Here, using tissue microarray and immunohistochemistry, we report that EMC6 protein is lost or reduced in glandular cells of patients with gastric adenocarcinoma, compared to normal stomach mucosa. Overexpression of EMC6 in gastric cancer cells inhibited cell growth, migration, invasion, and induced apoptosis and cell cycle arrest at S-phase. Further investigation suggested that EMC6 overexpression in BGC823 human adenocarcinoma gastric cancer cells reduced tumorigenicity in a xenograft model, demonstrating that EMC6 has the characteristics of a tumor suppressor. This is the first study to show that EMC6 induces cell death in gastric cancer cells. The molecular mechanism of how EMC6 functions as a tumor suppressor needs to be further explored. [BMB Reports 2017; 50(8): 411-416].
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Affiliation(s)
- Xiaokun Wang
- Departments of Cell Biology and Immunology, School of Basic Medical Science, Peking University, Beijing 100191, China
| | - Yan Xia
- Departments of Immunology, School of Basic Medical Science, Peking University, Beijing 100191, China
| | - Chentong Xu
- Departments of Immunology, School of Basic Medical Science, Peking University, Beijing 100191, China
| | - Xin Lin
- Departments of Immunology, School of Basic Medical Science, Peking University, Beijing 100191, China
| | - Peng Xue
- College of China-Japan Friendship Hospital, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Shijie Zhu
- Department of Oncology, Wangjing Hospital, China Academy of Chinese Medical Sciences, Beijing 100102, China
| | - Yun Bai
- Departments of Cell Biology, School of Basic Medical Science, Peking University, Beijing 100191, China
| | - Yingyu Chen
- Departments of Immunology, School of Basic Medical Science, Peking University, Beijing 100191, China
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44
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Breach: Host Membrane Penetration and Entry by Nonenveloped Viruses. Trends Microbiol 2017; 26:525-537. [PMID: 29079499 DOI: 10.1016/j.tim.2017.09.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 09/06/2017] [Accepted: 09/26/2017] [Indexed: 11/22/2022]
Abstract
Disruption of host membranes by nonenveloped viruses, which allows the nucleocapsid or genome to enter the cytosol, is a mechanistically diverse process. Although the membrane-penetrating agents are usually small, hydrophobic or amphipathic peptides deployed from the capsid interior during entry, their manner of membrane interaction varies substantially. In this review, we discuss recent data about the molecular pathways for externalization of viral peptides amidst conformational alterations in the capsid, as well as mechanisms of membrane penetration, which is influenced by structural features of the peptides themselves as well as physicochemical properties of membranes, and other host factors. The membrane-penetrating components of nonenveloped viruses constitute an interesting class of cell-penetrating peptides, and may have potential therapeutic value for gene transfer.
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45
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Dengue Virus Hijacks a Noncanonical Oxidoreductase Function of a Cellular Oligosaccharyltransferase Complex. mBio 2017; 8:mBio.00939-17. [PMID: 28720733 PMCID: PMC5516256 DOI: 10.1128/mbio.00939-17] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Dengue virus (DENV) is the most common arboviral infection globally, infecting an estimated 390 million people each year. We employed a genome-wide clustered regularly interspaced short palindromic repeat (CRISPR) screen to identify host dependency factors required for DENV propagation and identified the oligosaccharyltransferase (OST) complex as an essential host factor for DENV infection. Mammalian cells express two OSTs containing either STT3A or STT3B. We found that the canonical catalytic function of the OSTs as oligosaccharyltransferases is not necessary for DENV infection, as cells expressing catalytically inactive STT3A or STT3B are able to support DENV propagation. However, the OST subunit MAGT1, which associates with STT3B, is also required for DENV propagation. MAGT1 expression requires STT3B, and a catalytically inactive STT3B also rescues MAGT1 expression, supporting the hypothesis that STT3B serves to stabilize MAGT1 in the context of DENV infection. We found that the oxidoreductase CXXC active site motif of MAGT1 was necessary for DENV propagation, as cells expressing an AXXA MAGT1 mutant were unable to support DENV infection. Interestingly, cells expressing single-cysteine CXXA or AXXC mutants of MAGT1 were able to support DENV propagation. Utilizing the engineered peroxidase APEX2, we demonstrate the close proximity between MAGT1 and NS1 or NS4B during DENV infection. These results reveal that the oxidoreductase activity of the STT3B-containing OST is necessary for DENV infection, which may guide the development of antiviral agents targeting DENV. The host oligosaccharyltransferase (OST) complexes have been identified as essential host factors for dengue virus (DENV) replication; however, their functions during DENV infection are unclear. A previous study showed that the canonical OST activity was dispensable for DENV replication, suggesting that the OST complexes serve as scaffolds for DENV replication. However, our work demonstrates that one function of the OST complex during DENV infection is to provide oxidoreductase activity via the OST subunit MAGT1. We also show that MAGT1 associates with DENV NS1 and NS4B during viral infection, suggesting that these nonstructural proteins may be targets of MAGT1 oxidoreductase activity. These results provide insight into the cell biology of DENV infection, which may guide the development of antivirals against DENV.
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46
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Regulated Erlin-dependent release of the B12 transmembrane J-protein promotes ER membrane penetration of a non-enveloped virus. PLoS Pathog 2017; 13:e1006439. [PMID: 28614383 PMCID: PMC5484543 DOI: 10.1371/journal.ppat.1006439] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/26/2017] [Accepted: 05/30/2017] [Indexed: 12/16/2022] Open
Abstract
The molecular mechanism by which non-enveloped viruses penetrate biological membranes remains enigmatic. The non-enveloped polyomavirus SV40 penetrates the endoplasmic reticulum (ER) membrane to reach the cytosol and cause infection. We previously demonstrated that SV40 creates its own membrane penetration structure by mobilizing select transmembrane proteins to distinct puncta in the ER membrane called foci that likely function as the cytosol entry sites. How these ER membrane proteins reorganize into the foci is unknown. B12 is a transmembrane J-protein that mobilizes into the foci to promote cytosol entry of SV40. Here we identify two closely related ER membrane proteins Erlin1 and Erlin2 (Erlin1/2) as B12-interaction partners. Strikingly, SV40 recruits B12 to the foci by inducing release of this J-protein from Erlin1/2. Our data thus reveal how a non-enveloped virus promotes its own membrane translocation by triggering the release and recruitment of a critical transport factor to the membrane penetration site. Polyomavirus (PyV) is a non-enveloped DNA tumor virus that causes debilitating human diseases especially in immunocompromised individuals. At the cellular level, PyVs such as the simian PyV SV40 must enter a host cell and penetrate the ER membrane to reach the cytosol in order to cause infection. Prior to ER membrane transport, SV40 reorganizes select ER membrane proteins including the J-protein B12 to potential membrane penetration sites on the ER membrane called foci where B12 facilitates virus extraction into the cytosol. How B12 reorganizes into the foci is unclear. Here we find that two closely related ER membrane proteins Erlin1 and Erlin2 (Erlin1/2) bind to B12. During infection, SV40 induces release of this J-protein from Erlin1/2 to enable B12 to reorganize into the foci. Our data reveal how a non-enveloped virus mobilizes a specific ER membrane component to a membrane penetration structure to promote its own membrane transport.
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47
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[How polyomavirus crosses the endoplasmic reticulum membrane to gain entry into the cytosol]. Uirusu 2017; 67:121-132. [PMID: 30369536 DOI: 10.2222/jsv.67.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Polyomavirus (Py) is a non-enveloped, double stranded DNA virus that causes a myriad of devastating human diseases for immunocompromised individuals. To cause infection, Py binds to its receptors on the plasma membrane, is endocytosed, and sorts to the endoplasmic reticulum (ER). From here, Py penetrates the ER membrane to reach the cytosol. Ensuing nuclear entry enables the virus to cause infection. How Py penetrates the ER membrane to access the cytosol is a decisive infection step that is enigmatic. In this review, I highlight the mechanisms by which host cell functions facilitate Py translocation across the ER membrane into the cytosol.
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