1
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Vitali DG, Fonseca D, Carvalho P. The derlin Dfm1 couples retrotranslocation of a folded protein domain to its proteasomal degradation. J Cell Biol 2024; 223:e202308074. [PMID: 38448163 PMCID: PMC11066878 DOI: 10.1083/jcb.202308074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 12/05/2023] [Accepted: 02/14/2024] [Indexed: 03/08/2024] Open
Abstract
Endoplasmic reticulum (ER) proteins are degraded by proteasomes in the cytosol through ER-associated degradation (ERAD). This process involves the retrotranslocation of substrates across the ER membrane, their ubiquitination, and membrane extraction by the Cdc48/Npl4/Ufd1 ATPase complex prior to delivery to proteasomes for degradation. How the presence of a folded luminal domain affects substrate retrotranslocation and this event is coordinated with subsequent ERAD steps remains unknown. Here, using a model substrate with a folded luminal domain, we showed that Cdc48 ATPase activity is sufficient to drive substrate retrotranslocation independently of ERAD membrane components. However, the complete degradation of the folded luminal domain required substrate-tight coupling of retrotranslocation and proteasomal degradation, which was ensured by the derlin Dfm1. Mutations in Dfm1 intramembrane rhomboid-like or cytosolic Cdc48-binding regions resulted in partial degradation of the substrate with accumulation of its folded domain. Our study revealed Dfm1 as a critical regulator of Cdc48-driven retrotranslocation and highlights the importance of coordinating substrate retrotranslocation and degradation during ERAD.
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Affiliation(s)
- Daniela G. Vitali
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Daniel Fonseca
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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2
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Zoltek M, Vázquez Maldonado AL, Zhang X, Dadina N, Lesiak L, Schepartz A. HOPS-Dependent Endosomal Escape Demands Protein Unfolding. ACS CENTRAL SCIENCE 2024; 10:860-870. [PMID: 38680556 PMCID: PMC11046473 DOI: 10.1021/acscentsci.4c00016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/05/2024] [Accepted: 03/05/2024] [Indexed: 05/01/2024]
Abstract
The inefficient translocation of proteins across biological membranes limits their application as potential therapeutics and research tools. In many cases, the translocation of a protein involves two discrete steps: uptake into the endocytic pathway and endosomal escape. Certain charged or amphiphilic molecules can achieve high protein uptake, but few are capable of efficient endosomal escape. One exception to this rule is ZF5.3, a mini-protein that exploits elements of the natural endosomal maturation machinery to translocate across endosomal membranes. Although some ZF5.3-protein conjugates are delivered efficiently to the cytosol or nucleus, overall delivery efficiency varies widely for different cargoes with no obvious design rules. Here we show that delivery efficiency depends on the ability of the cargo to unfold. Using fluorescence correlation spectroscopy, a single-molecule technique that precisely measures intracytosolic protein concentration, we show that regardless of size and pI, low-Tm cargoes of ZF5.3 (including intrinsically disordered domains) bias endosomal escape toward a high-efficiency pathway that requires the homotypic fusion and protein sorting (HOPS) complex. Small protein domains are delivered with moderate efficiency through the same HOPS portal, even if the Tm is high. These findings imply a novel pathway out of endosomes that is exploited by ZF5.3 and provide clear guidance for the selection or design of optimally deliverable therapeutic cargo.
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Affiliation(s)
- Madeline Zoltek
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
| | | | - Xizi Zhang
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Neville Dadina
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Lauren Lesiak
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Alanna Schepartz
- Department
of Molecular and Cell Biology, University
of California, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- California
Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
- Chan
Zuckerberg Biohub, San Francisco, California 94158, United States
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3
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Lingwood C. Is cholesterol both the lock and key to abnormal transmembrane signals in Autism Spectrum Disorder? Lipids Health Dis 2024; 23:114. [PMID: 38643132 PMCID: PMC11032007 DOI: 10.1186/s12944-024-02075-3] [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: 12/12/2023] [Accepted: 03/08/2024] [Indexed: 04/22/2024] Open
Abstract
Disturbances in cholesterol homeostasis have been associated with ASD. Lipid rafts are central in many transmembrane signaling pathways (including mTOR) and changes in raft cholesterol content affect their order function. Cholesterol levels are controlled by several mechanisms, including endoplasmic reticulum associated degradation (ERAD) of the rate limiting HMGCoA reductase. A new approach to increase cholesterol via temporary ERAD blockade using a benign bacterial toxin-derived competitor for the ERAD translocon is suggested.A new lock and key model for cholesterol/lipid raft dependent signaling is proposed in which the rafts provide both the afferent and efferent 'tumblers' across the membrane to allow 'lock and key' receptor transmembrane signals.
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Affiliation(s)
- Clifford Lingwood
- Division of Molecular Medicine, Research Institute, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada.
- Departments of Biochemistry and Laboratory Medicine & Pathobiology, University of Toronto, Ontario, M5S 1A8, Canada.
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4
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Zoltek M, Vázquez A, Zhang X, Dadina N, Lesiak L, Schepartz A. Design rules for efficient endosomal escape. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.03.565388. [PMID: 37961597 PMCID: PMC10635116 DOI: 10.1101/2023.11.03.565388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
The inefficient translocation of proteins across biological membranes limits their application as therapeutic compounds and research tools. In most cases, translocation involves two steps: uptake into the endocytic pathway and endosomal escape. Certain charged or amphiphilic molecules promote protein uptake but few enable efficient endosomal escape. One exception is ZF5.3, a mini-protein that exploits natural endosomal maturation machinery to translocate across endosomal membranes. Although certain ZF5.3-protein conjugates are delivered efficiently into the cytosol or nucleus, overall delivery efficiency varies widely with no obvious design rules. Here we evaluate the role of protein size and thermal stability in the ability to efficiently escape endosomes when attached to ZF5.3. Using fluorescence correlation spectroscopy, a single-molecule technique that provides a precise measure of intra-cytosolic protein concentration, we demonstrate that delivery efficiency depends on both size and the ease with which a protein unfolds. Regardless of size and pI, low-Tm cargos of ZF5.3 (including intrinsically disordered domains) bias its endosomal escape route toward a high-efficiency pathway that requires the homotypic fusion and protein sorting (HOPS) complex. Small protein domains are delivered with moderate efficiency through the same HOPS portal even if the Tm is high. These findings imply a novel protein- and/or lipid-dependent pathway out of endosomes that is exploited by ZF5.3 and provide clear guidance for the selection or design of optimally deliverable therapeutic cargo.
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Affiliation(s)
- Madeline Zoltek
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Angel Vázquez
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Xizi Zhang
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Neville Dadina
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Lauren Lesiak
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Alanna Schepartz
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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5
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Liu YS, Wang Y, Zhou X, Zhang L, Yang G, Gao XD, Murakami Y, Fujita M, Kinoshita T. Accumulated precursors of specific GPI-anchored proteins upregulate GPI biosynthesis with ARV1. J Cell Biol 2023; 222:213904. [PMID: 36828365 PMCID: PMC9997660 DOI: 10.1083/jcb.202208159] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/27/2022] [Accepted: 01/30/2023] [Indexed: 02/26/2023] Open
Abstract
We previously reported that glycosylphosphatidylinositol (GPI) biosynthesis is upregulated when endoplasmic reticulum-associated degradation (ERAD) is defective; however, the underlying mechanistic basis remains unclear. Based on a genome-wide CRISPR-Cas9 screen, we show that a widely expressed GPI-anchored protein CD55 precursor and ER-resident ARV1 are involved in upregulation of GPI biosynthesis under ERAD-deficient conditions. In cells defective in GPI transamidase, GPI-anchored protein precursors fail to obtain GPI, with the remaining uncleaved GPI-attachment signal at the C-termini. We show that ERAD deficiency causes accumulation of the CD55 precursor, which in turn upregulates GPI biosynthesis, where the GPI-attachment signal peptide is the active element. Among the 31 GPI-anchored proteins tested, only the GPI-attachment signal peptides of CD55, CD48, and PLET1 enhance GPI biosynthesis. ARV1 is prerequisite for the GPI upregulation by CD55 precursor. Our data indicate that GPI biosynthesis is balanced to need by ARV1 and precursors of specific GPI-anchored proteins.
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Affiliation(s)
- Yi-Shi Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi, China
| | - Yicheng Wang
- Research Institute for Microbial Diseases, Osaka University , Suita, Japan.,WPI Immunology Frontier Research Center, Osaka University , Suita, Japan
| | - Xiaoman Zhou
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi, China
| | - Linpei Zhang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi, China
| | - Ganglong Yang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi, China
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi, China
| | - Yoshiko Murakami
- Research Institute for Microbial Diseases, Osaka University , Suita, Japan.,WPI Immunology Frontier Research Center, Osaka University , Suita, Japan
| | - Morihisa Fujita
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University , Wuxi, China.,Institute for Glyco-Core Research, Gifu University , Gifu, Japan
| | - Taroh Kinoshita
- Research Institute for Microbial Diseases, Osaka University , Suita, Japan.,WPI Immunology Frontier Research Center, Osaka University , Suita, Japan.,Center for Infectious Disease Education and Research, Osaka University , Suita, Japan
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6
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Wang L, Li J, Wang Q, Ge MX, Ji J, Liu D, Wang Z, Cao Y, Zhang Y, Zhang ZR. TMUB1 is an endoplasmic reticulum-resident escortase that promotes the p97-mediated extraction of membrane proteins for degradation. Mol Cell 2022; 82:3453-3467.e14. [PMID: 35961308 DOI: 10.1016/j.molcel.2022.07.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 05/15/2022] [Accepted: 07/12/2022] [Indexed: 02/06/2023]
Abstract
Membrane protein clients of endoplasmic reticulum (ER)-associated degradation must be retrotranslocated from the ER membrane by the AAA-ATPase p97 for proteasomal degradation. Before direct engagement with p97, client transmembrane domains (TMDs) that have partially or fully crossed the membrane must be constantly shielded to avoid non-native interactions. How client TMDs are seamlessly escorted from the membrane to p97 is unknown. Here, we identified ER-anchored TMUB1 as a TMD-specific escortase. TMUB1 interacts with the TMD of clients within the membrane and holds ∼10-14 residues of a hydrophobic sequence that is exposed out of membrane, using its transmembrane and cytosolic regions, respectively. The ubiquitin-like domain of TMUB1 recruits p97, which can pull client TMDs from bound TMUB1 into the cytosol. The disruption of TMUB1 escortase activity impairs retrotranslocation and stabilizes retrotranslocating intermediates of client proteins within the ER membrane. Thus, TMUB1 promotes TMD segregation by safeguarding the TMD movement from the membrane to p97.
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Affiliation(s)
- Linhan Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jiqiang Li
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Qingchen Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Man-Xi Ge
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Jia Ji
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Di Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Zhiyuan Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Yang Cao
- College of Life Sciences, Sichuan University, Chengdu, China
| | - Yaoyang Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China
| | - Zai-Rong Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Beijing, China.
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7
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Overexpression of MET4 Leads to the Upregulation of Stress-Related Genes and Enhanced Sulfite Tolerance in Saccharomyces uvarum. Cells 2022; 11:cells11040636. [PMID: 35203287 PMCID: PMC8869826 DOI: 10.3390/cells11040636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 12/10/2022] Open
Abstract
Saccharomyces uvarum is one of the few fermentative species that can be used in winemaking, but its weak sulfite tolerance is the main reason for its further use. Previous studies have shown that the expression of the methionine synthase gene (MET4) is upregulated in FZF1 (a gene encoding a putative zinc finger protein, which is a positive regulator of the transcription of the cytosolic sulfotransferase gene SSU1) overexpression transformant strains, but its exact function is unknown. To gain insight into the function of the MET4 gene, in this study, a MET4 overexpression vector was constructed and transformed into S. uvarum strain A9. The MET4 transformants showed a 20 mM increase in sulfite tolerance compared to the starting strain. Ninety-two differential genes were found in the transcriptome of A9-MET4 compared to the A9 strain, of which 90 were upregulated, and two were downregulated. The results of RT-qPCR analyses confirmed that the expression of the HOMoserine requiring gene (HOM3) in the sulfate assimilation pathway and some fermentation-stress-related genes were upregulated in the transformants. The overexpression of the MET4 gene resulted in a significant increase in sulfite tolerance, the upregulation of fermentation-stress-related gene expression, and significant changes in the transcriptome profile of the S. uvarum strain.
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8
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Deng X, Sun X, Yue W, Duan Y, Hu R, Zhang K, Ni J, Cui J, Wang Q, Chen Y, Li A, Fang Y. CHMP2B regulates TDP-43 phosphorylation and cytotoxicity independent of autophagy via CK1. J Cell Biol 2022; 221:212740. [PMID: 34726688 PMCID: PMC8570292 DOI: 10.1083/jcb.202103033] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 09/03/2021] [Accepted: 10/04/2021] [Indexed: 12/26/2022] Open
Abstract
The ESCRT protein CHMP2B and the RNA-binding protein TDP-43 are both associated with ALS and FTD. The pathogenicity of CHMP2B has mainly been considered a consequence of autophagy–endolysosomal dysfunction, whereas protein inclusions containing phosphorylated TDP-43 are a pathological hallmark of ALS and FTD. Intriguingly, TDP-43 pathology has not been associated with the FTD-causing CHMP2BIntron5 mutation. In this study, we identify CHMP2B as a modifier of TDP-43–mediated neurodegeneration in a Drosophila screen. Down-regulation of CHMP2B reduces TDP-43 phosphorylation and toxicity in flies and mammalian cells. Surprisingly, although CHMP2BIntron5 causes dramatic autophagy dysfunction, disturbance of autophagy does not alter TDP-43 phosphorylation levels. Instead, we find that inhibition of CK1, but not TTBK1/2 (all of which are kinases phosphorylating TDP-43), abolishes the modifying effect of CHMP2B on TDP-43 phosphorylation. Finally, we uncover that CHMP2B modulates CK1 protein levels by negatively regulating ubiquitination and the proteasome-mediated turnover of CK1. Together, our findings propose an autophagy-independent role and mechanism of CHMP2B in regulating CK1 abundance and TDP-43 phosphorylation.
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Affiliation(s)
- Xue Deng
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xing Sun
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Wenkai Yue
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yongjia Duan
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Rirong Hu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Kai Zhang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jiangxia Ni
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jihong Cui
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Qiangqiang Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Yelin Chen
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ang Li
- Guangdong Key Laboratory of Non-human Primate Research, Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, China.,Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China.,Key Laboratory of CNS Regeneration (Jinan University), Ministry of Education, Guangzhou, China.,Department of Neurology, Guangdong Neuroscience Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China
| | - Yanshan Fang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
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9
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Das P, Dudley JP. How Viruses Use the VCP/p97 ATPase Molecular Machine. Viruses 2021; 13:1881. [PMID: 34578461 PMCID: PMC8473244 DOI: 10.3390/v13091881] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 12/22/2022] Open
Abstract
Viruses are obligate intracellular parasites that are dependent on host factors for their replication. One such host protein, p97 or the valosin-containing protein (VCP), is a highly conserved AAA ATPase that facilitates replication of diverse RNA- and DNA-containing viruses. The wide range of cellular functions attributed to this ATPase is consistent with its participation in multiple steps of the virus life cycle from entry and uncoating to viral egress. Studies of VCP/p97 interactions with viruses will provide important information about host processes and cell biology, but also viral strategies that take advantage of these host functions. The critical role of p97 in viral replication might be exploited as a target for development of pan-antiviral drugs that exceed the capability of virus-specific vaccines or therapeutics.
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Affiliation(s)
- Poulami Das
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA;
| | - Jaquelin P. Dudley
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA;
- LaMontagne Center for Infectious Disease, The University of Texas at Austin, Austin, TX 78712, USA
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10
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Lingwood C. Therapeutic Uses of Bacterial Subunit Toxins. Toxins (Basel) 2021; 13:toxins13060378. [PMID: 34073185 PMCID: PMC8226680 DOI: 10.3390/toxins13060378] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/17/2021] [Accepted: 05/18/2021] [Indexed: 02/07/2023] Open
Abstract
The B subunit pentamer verotoxin (VT aka Shiga toxin-Stx) binding to its cellular glycosphingolipid (GSL) receptor, globotriaosyl ceramide (Gb3) mediates internalization and the subsequent receptor mediated retrograde intracellular traffic of the AB5 subunit holotoxin to the endoplasmic reticulum. Subunit separation and cytosolic A subunit transit via the ER retrotranslocon as a misfolded protein mimic, then inhibits protein synthesis to kill cells, which can cause hemolytic uremic syndrome clinically. This represents one of the most studied systems of prokaryotic hijacking of eukaryotic biology. Similarly, the interaction of cholera AB5 toxin with its GSL receptor, GM1 ganglioside, is the key component of the gastrointestinal pathogenesis of cholera and follows the same retrograde transport pathway for A subunit cytosol access. Although both VT and CT are the cause of major pathology worldwide, the toxin–receptor interaction is itself being manipulated to generate new approaches to control, rather than cause, disease. This arena comprises two areas: anti neoplasia, and protein misfolding diseases. CT/CTB subunit immunomodulatory function and anti-cancer toxin immunoconjugates will not be considered here. In the verotoxin case, it is clear that Gb3 (and VT targeting) is upregulated in many human cancers and that there is a relationship between GSL expression and cancer drug resistance. While both verotoxin and cholera toxin similarly hijack the intracellular ERAD quality control system of nascent protein folding, the more widespread cell expression of GM1 makes cholera the toxin of choice as the means to more widely utilise ERAD targeting to ameliorate genetic diseases of protein misfolding. Gb3 is primarily expressed in human renal tissue. Glomerular endothelial cells are the primary VT target but Gb3 is expressed in other endothelial beds, notably brain endothelial cells which can mediate the encephalopathy primarily associated with VT2-producing E. coli infection. The Gb3 levels can be regulated by cytokines released during EHEC infection, which complicate pathogenesis. Significantly Gb3 is upregulated in the neovasculature of many tumours, irrespective of tumour Gb3 status. Gb3 is markedly increased in pancreatic, ovarian, breast, testicular, renal, astrocytic, gastric, colorectal, cervical, sarcoma and meningeal cancer relative to the normal tissue. VT has been shown to be effective in mouse xenograft models of renal, astrocytoma, ovarian, colorectal, meningioma, and breast cancer. These studies are herein reviewed. Both CT and VT (and several other bacterial toxins) access the cell cytosol via cell surface ->ER transport. Once in the ER they interface with the protein folding homeostatic quality control pathway of the cell -ERAD, (ER associated degradation), which ensures that only correctly folded nascent proteins are allowed to progress to their cellular destinations. Misfolded proteins are translocated through the ER membrane and degraded by cytosolic proteosome. VT and CT A subunits have a C terminal misfolded protein mimic sequence to hijack this transporter to enter the cytosol. This interface between exogenous toxin and genetically encoded endogenous mutant misfolded proteins, provides a new therapeutic basis for the treatment of such genetic diseases, e.g., Cystic fibrosis, Gaucher disease, Krabbe disease, Fabry disease, Tay-Sachs disease and many more. Studies showing the efficacy of this approach in animal models of such diseases are presented.
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Affiliation(s)
- Clifford Lingwood
- Division of Molecular Medicine, Research Institute, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada;
- Departments of Laboratory Medicine & Pathobiology, and Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
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11
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Jin Y, Cheng X, Huang X, Ding F, Lee SR, Wang F, Lu X, Su D, Chen B. The role of Hrd1 in ultraviolet (UV) radiation induced photoaging. Aging (Albany NY) 2020; 12:21273-21289. [PMID: 33168784 PMCID: PMC7695362 DOI: 10.18632/aging.103851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 07/20/2020] [Indexed: 01/20/2023]
Abstract
The purpose of the present study was to evaluate the role of Hrd1 in the ultraviolet (UV) radiation induced photoaging and explore its potential mechanism. The nude mice were exposed to the UVA/UVB irradiation for 10 weeks. The animals were subcutaneously injected with AAV5-NC, Hrd1-shRNA-AAV5, or Hrd1-overexpression-AAV5. The HSF cells were also transfected with Ad-NC, Ad-shRNA-Hrd1, or Ad-Hrd1, and irradiated by UVA/UVB stimulation. The clinical skin samples were harvested for detecting Hrd1 and IGF-1R expressions. As a result, the knockdown of Hrd1 attenuated the histopathological alteration and collagen degradation in UV-induced nude mice. The inhibition of Hrd1 by Hrd1-shRNA-AAV5 and Ad-shRNA-Hrd1 inhibited the Hrd1 expression and promoted IGF-1R, Type I collagen and type III collagen in mice and HSF cells. The overexpression of Hrd1 exerted the reverse effect. The Co-IP assay also indicated the interaction between Hrd1 and IGF-1R. Hrd1-mediated IGF-1R downregulation and collagen degradation were also observed in clinical skin samples. In conclusion, the present results demonstrated that Hrd1 degraded IGF-1R and collagen formation in UV-induced photoaging.
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Affiliation(s)
- Yi Jin
- Department of Dermatology and Venereology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
| | - Xianye Cheng
- Department of Dermatology and Venereology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
| | - Xin Huang
- Department of Pediatric and Preventive Dentistry, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210029, China
| | - Fan Ding
- Department of Dermatology and Venereology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
| | - Sae Rom Lee
- Department of Dermatology and Venereology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
| | - Fengdi Wang
- Department of Dermatology and Venereology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
| | - Xiaoyi Lu
- Department of Dermatology and Venereology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
| | - Dongming Su
- Center of Metabolic Disease Research, Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
| | - Bin Chen
- Department of Dermatology and Venereology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, Jiangsu Province, China
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Hu X, Wang L, Wang Y, Ji J, Li J, Wang Z, Li C, Zhang Y, Zhang ZR. RNF126-Mediated Reubiquitination Is Required for Proteasomal Degradation of p97-Extracted Membrane Proteins. Mol Cell 2020; 79:320-331.e9. [DOI: 10.1016/j.molcel.2020.06.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 04/21/2020] [Accepted: 06/12/2020] [Indexed: 12/13/2022]
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Schmidt CC, Vasic V, Stein A. Doa10 is a membrane protein retrotranslocase in ER-associated protein degradation. eLife 2020; 9:56945. [PMID: 32588820 PMCID: PMC7319771 DOI: 10.7554/elife.56945] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 05/28/2020] [Indexed: 12/17/2022] Open
Abstract
In endoplasmic reticulum-associated protein degradation (ERAD), membrane proteins are ubiquitinated, extracted from the membrane, and degraded by the proteasome. The cytosolic ATPase Cdc48 drives extraction by pulling on polyubiquitinated substrates. How hydrophobic transmembrane (TM) segments are moved from the phospholipid bilayer into cytosol, often together with hydrophilic and folded ER luminal protein parts, is not known. Using a reconstituted system with purified proteins from Saccharomyces cerevisiae, we show that the ubiquitin ligase Doa10 (Teb-4/MARCH6 in animals) is a retrotranslocase that facilitates membrane protein extraction. A substrate’s TM segment interacts with the membrane-embedded domain of Doa10 and then passively moves into the aqueous phase. Luminal substrate segments cross the membrane in an unfolded state. Their unfolding occurs on the luminal side of the membrane by cytoplasmic Cdc48 action. Our results reveal how a membrane-bound retrotranslocase cooperates with the Cdc48 ATPase in membrane protein extraction. The inside of a cell contains many different compartments called organelles, which are separated by membranes. Each organelle is composed of a unique set of proteins and performs specific roles in the cell. The endoplasmic reticulum, or ER for short, is an organelle where many proteins are produced. Most of these proteins are then released from the cell or sorted to other organelles. The ER has a strict quality control system that ensures any faulty proteins are quickly marked for the cell to destroy. However, the destruction process itself does not happen in the ER, so faulty proteins first need to leave this organelle. This is achieved by a group of proteins known as endoplasmic reticulum-associated protein degradation machinery (or ERAD for short). To extract a faulty protein from the ER, proteins of the ER and outside the ER cooperate. First, an ERAD protein called Doa10 attaches a small protein tag called ubiquitin to the faulty proteins to mark them for destruction. Then, outside of the ER, a protein called Cdc48 ‘grabs’ the ubiquitin tag and pulls. But that is only part of the story. Many of the proteins made by the ER have tethers that anchor them firmly to the membrane, making them much harder to remove. To get a better idea of how the extraction works, Schmidt et al. rebuilt the ERAD machinery in a test tube. This involved purifying proteins from yeast and inserting them into artificial membranes, allowing closer study of each part of the process. This revealed that attaching ubiquitin tags to faulty proteins is only one part of Doa10's role; it also participates in the extraction itself. Part of Doa10 resides within the membrane, and this ‘membrane-spanning domain’ can interact with faulty proteins, loosening their membrane anchors. At the same time, Cdc48 pulls from the outside. This pulling force causes the faulty proteins to unfold, allowing them to pass through the membrane. Given these findings, the next step is to find out exactly how Doa10 works by looking at its three-dimensional structure. This could have implications not only for the study of ERAD, but of similar quality control processes in other organelles too. A build-up of faulty proteins can cause diseases like neurodegeneration, so understanding how cells remove faulty proteins could help future medical research.
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Affiliation(s)
- Claudia C Schmidt
- Research Group Membrane Protein Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Vedran Vasic
- Research Group Membrane Protein Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Alexander Stein
- Research Group Membrane Protein Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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