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Yang E, Fan X, Ye H, Sun X, Ji Q, Ding Q, Zhong S, Zhao S, Xuan C, Fang M, Ding X, Cao J. Exploring the role of ubiquitin regulatory X domain family proteins in cancers: bioinformatics insights, mechanisms, and implications for therapy. J Transl Med 2024; 22:157. [PMID: 38365777 PMCID: PMC10870615 DOI: 10.1186/s12967-024-04890-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 01/13/2024] [Indexed: 02/18/2024] Open
Abstract
UBXD family (UBXDF), a group of proteins containing ubiquitin regulatory X (UBX) domains, play a crucial role in the imbalance of proliferation and apoptotic in cancer. In this study, we summarised bioinformatics proof on multi-omics databases and literature on UBXDF's effects on cancer. Bioinformatics analysis revealed that Fas-associated factor 1 (FAF1) has the largest number of gene alterations in the UBXD family and has been linked to survival and cancer progression in many cancers. UBXDF may affect tumour microenvironment (TME) and drugtherapy and should be investigated in the future. We also summarised the experimental evidence of the mechanism of UBXDF in cancer, both in vitro and in vivo, as well as its application in clinical and targeted drugs. We compared bioinformatics and literature to provide a multi-omics insight into UBXDF in cancers, review proof and mechanism of UBXDF effects on cancers, and prospect future research directions in-depth. We hope that this paper will be helpful for direct cancer-related UBXDF studies.
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Affiliation(s)
- Enyu Yang
- School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Xiaowei Fan
- School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Haihan Ye
- School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Xiaoyang Sun
- School of Biological Sciences, The University of Hong Kong, Hong Kong , 999077, Special Administrative Region, China
| | - Qing Ji
- Key Laboratory of Head & Neck Cancer Translational Research of Zhejiang Province, Department of Head and Neck and Rare Oncology, Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, 310022, China
| | - Qianyun Ding
- Department of 'A', The Children's Hospital, National Clinical Research Center for Child Health, Zhejiang University School of Medicine, Hangzhou, 310003, China
| | - Shulian Zhong
- Zhejiang Sci-Tech University Hospital, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Shuo Zhao
- School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Cheng Xuan
- School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China
| | - Meiyu Fang
- Key Laboratory of Head & Neck Cancer Translational Research of Zhejiang Province, Department of Head and Neck and Rare Oncology, Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, 310022, China.
| | - Xianfeng Ding
- School of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
| | - Jun Cao
- Key Laboratory of Head & Neck Cancer Translational Research of Zhejiang Province, Department of Head and Neck and Rare Oncology, Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, 310022, China.
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Zheng J, Cao Y, Yang J, Jiang H. UBXD8 mediates mitochondria-associated degradation to restrain apoptosis and mitophagy. EMBO Rep 2022; 23:e54859. [PMID: 35979733 PMCID: PMC9535754 DOI: 10.15252/embr.202254859] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 07/20/2022] [Accepted: 08/04/2022] [Indexed: 08/08/2023] Open
Abstract
The hexameric AAA-ATPase valosin-containing protein (VCP) is essential for mitochondrial protein quality control. How VCP is recruited to mammalian mitochondria remains obscure. Here we report that UBXD8, an ER- and lipid droplet-localized VCP adaptor, also localizes to mitochondria and locally recruits VCP. UBXD8 associates with mitochondrial and ER ubiquitin E3 ligases and targets their substrates for degradation. Remarkably, both mitochondria- and ER-localized UBXD8 can degrade mitochondrial and ER substrates in cis and in trans. UBXD8 also associates with the TOM complex but is dispensable for translocation-associated degradation. UBXD8 knockout impairs the degradation of the pro-survival protein Mcl1 but surprisingly sensitizes cells to apoptosis and mitochondrial stresses. UBXD8 knockout also hyperactivates mitophagy. We identify pro-apoptotic BH3-only proteins Noxa, Bik, and Bnip3 as novel UBXD8 substrates and determine that UBXD8 inhibits apoptosis via degrading Noxa and restrains mitophagy via degrading Bnip3. Collectively, our characterizations reveal UBXD8 as the major mitochondrial adaptor of VCP and unveil its role in apoptosis and mitophagy regulation.
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Affiliation(s)
- Jing Zheng
- School of Life SciencesPeking UniversityBeijingChina
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
| | - Yu Cao
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
- College of Life SciencesBeijing Normal UniversityBeijingChina
| | - Jun Yang
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
- School of Life SciencesTsinghua UniversityBeijingChina
| | - Hui Jiang
- School of Life SciencesPeking UniversityBeijingChina
- National Institute of Biological SciencesBeijingChina
- Beijing Key Laboratory of Cell Biology for Animal AgingBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical ResearchTsinghua UniversityBeijingChina
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Epigenetic silencing of UBXN8 contributes to leukemogenesis in t(8;21) acute myeloid leukemia. Exp Mol Med 2021; 53:1902-1910. [PMID: 34921223 PMCID: PMC8741982 DOI: 10.1038/s12276-021-00695-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 07/01/2021] [Accepted: 07/02/2021] [Indexed: 11/21/2022] Open
Abstract
The formation of the RUNX1-RUNX1T1 fusion protein, resulting from the t(8;21) translocation, is considered to be one of the initiating events of t(8;21) acute myeloid leukemia (AML). However, the mechanisms of the oncogenic mechanism of RUNX1-RUNX1T1 remain unclear. In this study, we found that RUNX1-RUNX1T1 triggers the heterochromatic silencing of UBXN8 by recognizing the RUNX1-binding sites and recruiting chromatin-remodeling enzymes to the UBXN8 promoter region. Decitabine, a specific inhibitor of DNA methylation, upregulated the expression of UBXN8 in RUNX1-RUNX1T1+ AML cell lines. Overexpression of UBXN8 inhibited the proliferation and colony-forming ability of and promoted cell cycle arrest in t(8;21) AML cell lines. Enhancing UBXN8 levels can significantly inhibit tumor proliferation and promote the differentiation of RUNX1-RUNX1T1+ cells in vivo. In conclusion, our results indicated that epigenetic silencing of UBXN8 via methylation of its promoter region mediated by the RUNX1-RUNX1T1 fusion protein contributes to the leukemogenesis of t(8;21) AML and that UBXN8 targeting may be a potential therapeutic strategy for t(8;21) AML. The protein byproduct of a common chromosomal rearrangement in acute myeloid leukemia (AML) promotes cancerous growth by inhibiting a tumor suppressor protein. AML cells that exhibit an abnormal coupling of segments from chromosomes 8 and 21 produce a fusion protein known as RUNX1-RUNX1T1. Erna Yang of Shenzhen University General Hospital, China, and colleagues have identified a mechanism by which this protein promotes AML progression. Experiments with AML cell lines showed that RUNX1-RUNX1T1 recruits DNA-binding proteins that introduce numerous chemical modifications to the UBXN8 gene, which inhibit production of the tumor suppressor protein it codes for. Drugs that block these modifications and stimulate UBXN8 activity also arrest tumor cell division. Experiments in mice confirmed that enhanced UBXN8 expression offers a defense against AML progression, suggesting a promising therapeutic approach.
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Ye Y, Tang WK, Zhang T, Xia D. A Mighty "Protein Extractor" of the Cell: Structure and Function of the p97/CDC48 ATPase. Front Mol Biosci 2017; 4:39. [PMID: 28660197 PMCID: PMC5468458 DOI: 10.3389/fmolb.2017.00039] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 05/22/2017] [Indexed: 12/13/2022] Open
Abstract
p97/VCP (known as Cdc48 in S. cerevisiae or TER94 in Drosophila) is one of the most abundant cytosolic ATPases. It is highly conserved from archaebacteria to eukaryotes. In conjunction with a large number of cofactors and adaptors, it couples ATP hydrolysis to segregation of polypeptides from immobile cellular structures such as protein assemblies, membranes, ribosome, and chromatin. This often results in proteasomal degradation of extracted polypeptides. Given the diversity of p97 substrates, this "segregase" activity has profound influence on cellular physiology ranging from protein homeostasis to DNA lesion sensing, and mutations in p97 have been linked to several human diseases. Here we summarize our current understanding of the structure and function of this important cellular machinery and discuss the relevant clinical implications.
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Affiliation(s)
- Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD, United States
| | - Wai Kwan Tang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of HealthBethesda, MD, United States
| | - Ting Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesda, MD, United States
| | - Di Xia
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of HealthBethesda, MD, United States
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Rezvani K. UBXD Proteins: A Family of Proteins with Diverse Functions in Cancer. Int J Mol Sci 2016; 17:ijms17101724. [PMID: 27754413 PMCID: PMC5085755 DOI: 10.3390/ijms17101724] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 09/24/2016] [Accepted: 10/08/2016] [Indexed: 12/15/2022] Open
Abstract
The UBXD family is a diverse group of UBX (ubiquitin-regulatory X) domain-containing proteins in mammalian cells. Members of this family contain a UBX domain typically located at the carboxyl-terminal of the protein. In contrast to the UBX domain shared by all members of UBXD family, the amino-terminal domains are diverse and appear to carry out different roles in a subcellular localization-dependent manner. UBXD proteins are principally associated with the endoplasmic reticulum (ER), where they positively or negatively regulate the ER-associated degradation machinery (ERAD). The distinct protein interaction networks of UBXD proteins allow them to have specific functions independent of the ERAD pathway in a cell type- and tissue context-dependent manner. Recent reports have illustrated that a number of mammalian members of the UBXD family play critical roles in several proliferation and apoptosis pathways dysregulated in selected types of cancer. This review covers recent advances that elucidate the therapeutic potential of selected members of the UBXD family that can contribute to tumor growth.
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Affiliation(s)
- Khosrow Rezvani
- Division of Basic Biomedical Sciences, Sanford School of Medicine, The University of South Dakota, 414 E. Clark Street, Lee Medical Building, Vermillion, SD 57069, USA.
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Systematic proteomics of the VCP-UBXD adaptor network identifies a role for UBXN10 in regulating ciliogenesis. Nat Cell Biol 2015; 17:1356-69. [PMID: 26389662 PMCID: PMC4610257 DOI: 10.1038/ncb3238] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 08/13/2015] [Indexed: 02/07/2023]
Abstract
The AAA-ATPase VCP (also known as p97 or CDC48) uses ATP hydrolysis to 'segregate' ubiquitylated proteins from their binding partners. VCP acts through UBX-domain-containing adaptors that provide target specificity, but the targets and functions of UBXD proteins remain poorly understood. Through systematic proteomic analysis of UBXD proteins in human cells, we reveal a network of over 195 interacting proteins, implicating VCP in diverse cellular pathways. We have explored one such complex between an unstudied adaptor UBXN10 and the intraflagellar transport B (IFT-B) complex, which regulates anterograde transport into cilia. UBXN10 localizes to cilia in a VCP-dependent manner and both VCP and UBXN10 are required for ciliogenesis. Pharmacological inhibition of VCP destabilized the IFT-B complex and increased trafficking rates. Depletion of UBXN10 in zebrafish embryos causes defects in left-right asymmetry, which depends on functional cilia. This study provides a resource for exploring the landscape of UBXD proteins in biology and identifies an unexpected requirement for VCP-UBXN10 in ciliogenesis.
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Human ASPL/TUG interacts with p97 and complements the proteasome mislocalization of a yeast ubx4 mutant, but not the ER-associated degradation defect. BMC Cell Biol 2014; 15:31. [PMID: 25078495 PMCID: PMC4124494 DOI: 10.1186/1471-2121-15-31] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/23/2014] [Indexed: 11/21/2022] Open
Abstract
Background In mammalian cells, ASPL is involved in insulin-stimulated redistribution of the glucose transporter GLUT4 and assembly of the Golgi apparatus. Its putative yeast orthologue, Ubx4, is important for proteasome localization, endoplasmic reticulum-associated protein degradation (ERAD), and UV-induced degradation of RNA polymerase. Results Here, we show that ASPL is a cofactor of the hexameric ATPase complex, known as p97 or VCP in mammals and Cdc48 in yeast. In addition, ASPL interacts in vitro with NSF, another hexameric ATPase complex. ASPL localizes to the ER membrane. The central area in ASPL, containing both a SHP box and a UBX domain, is required for binding to the p97 N-domain. Knock-down of ASPL does not impair degradation of misfolded secretory proteins via the ERAD pathway. Deletion of UBX4 in yeast causes cycloheximide sensitivity, while ubx4 cdc48-3 double mutations cause proteasome mislocalization. ASPL alleviates these defects, but not the impaired ERAD. Conclusions In conclusion, ASPL and Ubx4 are homologous proteins with only partially overlapping functions. Both interact with p97/Cdc48, but while Ubx4 is important for ERAD, ASPL appears not to share this function.
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Li X, Zhang J, Yang Z, Kang J, Jiang S, Zhang T, Chen T, Li M, Lv Q, Chen X, McCrae MA, Zhuang H, Lu F. The function of targeted host genes determines the oncogenicity of HBV integration in hepatocellular carcinoma. J Hepatol 2014; 60:975-84. [PMID: 24362074 DOI: 10.1016/j.jhep.2013.12.014] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 12/09/2013] [Accepted: 12/10/2013] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Although hepatitis B virus (HBV) integration into the human genome has been considered as one of the major causative factors to hepatocarcinogenesis, the underlying mechanism(s) was still elusive. Here we investigate the essential difference(s) of HBV integration between HCC tumor and adjacent non-tumor tissues and explore the factor(s) that determine the oncogenicity of HBV integration. METHODS 1115 HBV integration sites were collected from four recent studies. Functional annotation analysis of integration targeted host genes (ITGs) was performed using DAVID based on Gene Ontology and KEGG pathway databases. Array-based expression profiles, real-time qPCR and western blot were used to detect the expression of recurrent integration targeted genes (RTGs). The biological consequences of the overexpression of UBXN8 in 8 HCC cell lines were studied in vitro. RESULTS HBV is prone to integrate in genic regions (exons, introns, and promoters) and gene-dense regions. Functional annotation analysis reveals that, compared to those in adjacent non-tumor tissues, ITGs in HCC tumor tissues were significantly enriched in functional terms related to negative regulation of cell death, transcription regulation, development and differentiation, and cancer related pathways. 32% of the 75 RTGs identified in this analysis expressed abnormally in HCC tissues. UBXN8, one of the RTGs, was identified as a new tumor suppressor candidate which functions in a TP53 dependent manner. CONCLUSIONS The oncogenicity of HBV integration was determined, to some extend by the function of HBV integration targeted host genes in HCC.
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Affiliation(s)
- Xiaojun Li
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China
| | - Jiangbo Zhang
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China
| | - Ziwei Yang
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China
| | - Jingting Kang
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China
| | - Suzhen Jiang
- Department of Gastroenterology & Hepatology, Chinese PLA General Hospital, Beijing, PR China
| | - Ting Zhang
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China
| | - Tingting Chen
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China
| | - Meng Li
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China
| | - Quanjun Lv
- Department of Nutrition and Food Hygiene, College of Public Health, Zhengzhou University, Henan, PR China
| | - Xiangmei Chen
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China.
| | | | - Hui Zhuang
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China
| | - Fengmin Lu
- Department of Microbiology & Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, PR China.
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Talakhun W, Khamnamtong B, Nounurai P, Klinbunga S, Menasveta P. Characterization, expression and localization of valosin-containing protein in ovaries of the giant tiger shrimp Penaeus monodon. Gene 2013; 533:188-98. [PMID: 24095778 DOI: 10.1016/j.gene.2013.09.089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 09/23/2013] [Accepted: 09/24/2013] [Indexed: 11/30/2022]
Abstract
Valosin-containing protein (VCP), a member of the ATPase-associated with diverse cellular activity (AAA) family, was identified from the giant tiger shrimp (Penaeus monodon). The full-length cDNA of the PmVCP mRNA consisted of 2,724 bp containing an ORF of 2,367 bp corresponding to a deduced polypeptide of 788 amino acids. The deduced PmVCP protein contained two putative Cdc48 domains (positions 17-103, E-value=2.00e-36 and 120-186, E-value=3.60e-11) and two putative AAA domains (positions 232-368, E-value=3.67e-24 and 505-644, E-value=3.73e-25). PmVCP mRNA expression in ovaries was greater than that in testes in both juveniles and broodstock. PmVCP was significantly up-regulated in stages II and IV ovaries in intact wild broodstock (P<0.05) but it was not differentially expressed during ovarian development in eyestalk-ablated broodstock (P>0.05). The expression level of PmVCP mRNA in ovaries of 14-month-old shrimp was not affected by progesterone injection (0.1μg/g body weight, P>0.05). In contrast, exogenous 5-HT administration (50μg/g body weight) resulted in an increase of PmVCP mRNA in ovaries of 18-month-old shrimp at 6 and 24h post-injection (hpi) (P<0.05). The rPmCdc48-VCP protein and its polyclonal antibody were successfully produced. Cellular localization revealed that PmVCP was localized in the ooplasm of previtellogenic oocytes. Subsequently, it was translocated into the germinal vesicle of vitellogenic oocytes. Interestingly, PmVCP was found in nucleo-cytoplasmic compartments, in the cytoskeletal architecture and in the plasma membrane of mature oocytes in both intact and eyestalk-ablated broodstock.
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Affiliation(s)
- Witchulada Talakhun
- Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
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Liu J, Li F, Rozovsky S. The intrinsically disordered membrane protein selenoprotein S is a reductase in vitro. Biochemistry 2013; 52:3051-61. [PMID: 23566202 DOI: 10.1021/bi4001358] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Selenoprotein S (SelS or VIMP) is an intrinsically disordered membrane enzyme that provides protection against reactive oxidative species. SelS is a member of the endoplasmic reticulum-associated protein degradation pathway, but its precise enzymatic function is unknown. Because it contains the rare amino acid selenocysteine, it belongs to the family of selenoproteins, which are typically oxidoreductases. Its exact enzymatic function is key to understanding how the cell regulates the response to oxidative stress and thus influences human health and aging. To identify its enzymatic function, we have isolated the selenocysteine-containing enzyme by relying on the aggregation of forms that do not have this reactive residue. That allows us to establish that SelS is primarily a thioredoxin-dependent reductase. It is capable of reducing hydrogen peroxide but is not an efficient or broad-spectrum peroxidase. Only the selenocysteine-containing enzyme is active. In addition, the reduction potential of SelS was determined to be -234 mV using electrospray ionization mass spectrometry. This value is consistent with SelS being a partner of thioredoxin. On the basis of this information, SelS can directly combat reactive oxygen species but is also likely to participate in a signaling pathway, via a yet unidentified substrate.
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Affiliation(s)
- Jun Liu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
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Franz A, Ackermann L, Hoppe T. Create and preserve: proteostasis in development and aging is governed by Cdc48/p97/VCP. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:205-15. [PMID: 23583830 DOI: 10.1016/j.bbamcr.2013.03.031] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 03/08/2013] [Accepted: 03/25/2013] [Indexed: 12/24/2022]
Abstract
The AAA-ATPase Cdc48 (also called p97 or VCP) acts as a key regulator in proteolytic pathways, coordinating recruitment and targeting of substrate proteins to the 26S proteasome or lysosomal degradation. However, in contrast to the well-known function in ubiquitin-dependent cellular processes, the physiological relevance of Cdc48 in organismic development and maintenance of protein homeostasis is less understood. Therefore, studies on multicellular model organisms help to decipher how Cdc48-dependent proteolysis is regulated in time and space to meet developmental requirements. Given the importance of developmental regulation and tissue maintenance, defects in Cdc48 activity have been linked to several human pathologies including protein aggregation diseases. Thus, addressing the underlying disease mechanisms not only contributes to our understanding on the organism-wide function of Cdc48 but also facilitates the design of specific medical therapies. In this review, we will portray the role of Cdc48 in the context of multicellular organisms, pointing out its importance for developmental processes, tissue surveillance, and disease prevention. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf.
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Affiliation(s)
- André Franz
- Institute for Genetics and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany
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Distribution of the SELMA translocon in secondary plastids of red algal origin and predicted uncoupling of ubiquitin-dependent translocation from degradation. EUKARYOTIC CELL 2012; 11:1472-81. [PMID: 23042132 DOI: 10.1128/ec.00183-12] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Protein import into complex plastids of red algal origin is a multistep process including translocons of different evolutionary origins. The symbiont-derived ERAD-like machinery (SELMA), shown to be of red algal origin, is proposed to be the transport system for preprotein import across the periplastidal membrane of heterokontophytes, haptophytes, cryptophytes, and apicomplexans. In contrast to the canonical endoplasmic reticulum-associated degradation (ERAD) system, SELMA translocation is suggested to be uncoupled from proteasomal degradation. We investigated the distribution of known and newly identified SELMA components in organisms with complex plastids of red algal origin by intensive data mining, thereby defining a set of core components present in all examined organisms. These include putative pore-forming components, a ubiquitylation machinery, as well as a Cdc48 complex. Furthermore, the set of known 20S proteasomal components in the periplastidal compartment (PPC) of diatoms was expanded. These newly identified putative SELMA components, as well as proteasomal subunits, were in vivo localized as PPC proteins in the diatom Phaeodactylum tricornutum. The presented data allow us to speculate about the specific features of SELMA translocation in contrast to the canonical ERAD system, especially the uncoupling of translocation from degradation.
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