51
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Culver JA, Mariappan M. Deubiquitinases USP20/33 promote the biogenesis of tail-anchored membrane proteins. J Cell Biol 2021; 220:211933. [PMID: 33792613 PMCID: PMC8020466 DOI: 10.1083/jcb.202004086] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 12/19/2020] [Accepted: 02/24/2021] [Indexed: 12/12/2022] Open
Abstract
Numerous proteins that have hydrophobic transmembrane domains (TMDs) traverse the cytosol and posttranslationally insert into cellular membranes. It is unclear how these hydrophobic membrane proteins evade recognition by the cytosolic protein quality control (PQC), which typically recognizes exposed hydrophobicity in misfolded proteins and marks them for proteasomal degradation by adding ubiquitin chains. Here, we find that tail-anchored (TA) proteins, a vital class of membrane proteins, are recognized by cytosolic PQC and are ubiquitinated as soon as they are synthesized in cells. Surprisingly, the ubiquitinated TA proteins are not routed for proteasomal degradation but instead are handed over to the targeting factor, TRC40, and delivered to the ER for insertion. The ER-associated deubiquitinases, USP20 and USP33, remove ubiquitin chains from TA proteins after their insertion into the ER. Thus, our data suggest that deubiquitinases rescue posttranslationally targeted membrane proteins that are inappropriately ubiquitinated by PQC in the cytosol.
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Affiliation(s)
- Jacob A Culver
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, CT
| | - Malaiyalam Mariappan
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, West Haven, CT
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52
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Fry MY, Saladi SM, Clemons WM. The STI1-domain is a flexible alpha-helical fold with a hydrophobic groove. Protein Sci 2021; 30:882-898. [PMID: 33620121 PMCID: PMC7980504 DOI: 10.1002/pro.4049] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 01/05/2023]
Abstract
STI1-domains are present in a variety of co-chaperone proteins and are required for the transfer of hydrophobic clients in various cellular processes. The domains were first identified in the yeast Sti1 protein where they were referred to as DP1 and DP2. Based on hidden Markov model searches, this domain had previously been found in other proteins including the mammalian co-chaperone SGTA, the DNA damage response protein Rad23, and the chloroplast import protein Tic40. Here, we refine the domain definition and carry out structure-based sequence alignment of STI1-domains showing conservation of five amphipathic helices. Upon examinations of these identified domains, we identify a preceding helix 0 and unifying sequence properties, determine new molecular models, and recognize that STI1-domains nearly always occur in pairs. The similarity at the sequence, structure, and molecular levels likely supports a unified functional role.
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Affiliation(s)
- Michelle Y. Fry
- Division of Chemistry and Chemical EngineeringCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - Shyam M. Saladi
- Division of Chemistry and Chemical EngineeringCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - William M. Clemons
- Division of Chemistry and Chemical EngineeringCalifornia Institute of TechnologyPasadenaCaliforniaUSA
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53
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Hoefer F, Groettrup M. Silencing of the proteasome and oxidative stress impair endoplasmic reticulum targeting and signal cleavage of a prostate carcinoma antigen. Biochem Biophys Res Commun 2021; 554:56-62. [PMID: 33774280 DOI: 10.1016/j.bbrc.2021.03.023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 03/04/2021] [Indexed: 10/21/2022]
Abstract
The endoplasmic reticulum (ER) is an organelle with high protein density and therefore prone to be damaged by protein aggregates. One proposed preventive measure is a pre-emptive quality control pathway that attenuates ER import during protein folding stress. ER resident proteins are targeted into the ER via signal peptides cleaved rapidly upon ER insertion by the ER signal peptidase. Here we show that the ER insertion and cleavage of the ER-targeting peptide of the prostate carcinoma antigen prostate stem cell antigen (PSCA) is retarded and strongly reduced when the proteasome is inhibited or genetically silenced. Also overexpression of the C-terminally extended ubiquitin variant Ub2-UBB+1 or oxidative stress attenuated signal peptide processing. Proteasome inhibition likewise protracted ER signal processing of the ER targeted hormone leptin and the MHC class I molecule H-2Dd. These findings, which are consistent with a pre-emptive ER quality control pathway, may explain why an immunodominant MHC class I peptide ligand of PSCA spanning its ER signal peptidase cleavage site is efficiently generated in the cytoplasm from PSCA precursors that fail to reach the ER.
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Affiliation(s)
- Franziska Hoefer
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany
| | - Marcus Groettrup
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany; Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland.
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54
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Huang C, Min Y, Liu J, Li J, Yang X. Ring finger protein 126: a potential biomarker for colorectal cancer. Histol Histopathol 2021; 36:559-566. [PMID: 33724438 DOI: 10.14670/hh-18-328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Colorectal cancer (CRC) is the most common cancer of the digestive system. However, effective therapeutic targets against CRC have not been found yet. Further, the relationship between the expression of ring finger protein 126 (RNF126) and CRC is not clear. MATERIAL AND METHODS The expression level of RNF126 in CRC tissues and cell lines was detected by immunohistochemical staining and western blot. Subsequently, endogenous RNF126 expression was inhibited in a CRC cell line using a short hairpin RNA. Next, the effect of RNF126 on the properties of CRC cells was studied through different experimental methods. RESULTS We found that the RNF126 protein was mainly localized in the cytoplasm. High RNF126 expression was observed to be an independent risk factor for poor prognosis in CRC patients. In vitro studies showed that RNF126 was able to promote the proliferation, migration, and invasion ability of CRC cells. CONCLUSION RNF126 acts as an oncogene during CRC development, and may serve as a novel target for CRC treatment.
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Affiliation(s)
- Chaoqun Huang
- Department of Gastrointestinal Surgery, Zhongnan Hospital of Wuhan University, Wuhan, Hubei Province, PR China.,Key Laboratory of Tumor Biological Behavior of Hubei Provence, Wuhan, Hubei Province, PR China.,Clinical Cancer Study Center of Hubei Provence, Wuhan, Hubei Province, PR China
| | - Yao Min
- The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, PR China
| | - Jiuyang Liu
- Key Laboratory of Tumor Biological Behavior of Hubei Provence, Wuhan, Hubei Province, PR China.,Clinical Cancer Study Center of Hubei Provence, Wuhan, Hubei Province, PR China.,Department of Thyroid and Breast Surgery, Zhongnan Hospital of Wuhan University, Wuhan, Hubei Province, PR China
| | - Jing Li
- The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, PR China.
| | - Xiaojun Yang
- Department of Gastrointestinal Surgery, Zhongnan Hospital of Wuhan University, Wuhan, Hubei Province, PR China.,Key Laboratory of Tumor Biological Behavior of Hubei Provence, Wuhan, Hubei Province, PR China.,Clinical Cancer Study Center of Hubei Provence, Wuhan, Hubei Province, PR China.
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55
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Xu H, Ju L, Xiong Y, Yu M, Zhou F, Qian K, Wang G, Xiao Y, Wang X. E3 ubiquitin ligase RNF126 affects bladder cancer progression through regulation of PTEN stability. Cell Death Dis 2021; 12:239. [PMID: 33664240 PMCID: PMC7933351 DOI: 10.1038/s41419-021-03521-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 02/10/2021] [Accepted: 02/12/2021] [Indexed: 01/31/2023]
Abstract
E3 ubiquitin ligase RNF126 (ring finger protein 126) is highly expressed in various cancers and strongly associated with tumorigenesis. However, its specific function in bladder cancer (BCa) is still debatable. Here, we found that RNF126 was significantly upregulated in BCa tissue by TCGA database, and our studies indicated that downregulation of RNF126 significantly inhibited cell proliferation and metastasis through the EGFR/PI3K/AKT signaling pathway in BCa cells. Furthermore, we identified PTEN, an inhibitor of the PI3K/AKT signaling pathway, as a novel substrate for RNF126. By co-immunoprecipitation assays, we proved that RNF126 directly interacts with PTEN. Predominantly, PTEN binds to the C-terminal containing the RING domain of RNF126. The in vivo ubiquitination assay showed that RNF126 specifically regulates PTEN stability through poly-ubiquitination. Furthermore, PTEN knockdown restored cell proliferation, metastasis, and tumor formation of BCa cells inhibited by RNF126 silencing in vitro and in vivo. In conclusion, these results identified RNF126 as an oncogene that functions through ubiquitination and degradation of PTEN in BCa.
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Affiliation(s)
- Huimin Xu
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Lingao Ju
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China.
- Human Genetic Resource Preservation Center of Hubei Province, Wuhan, China.
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China.
- Laboratory of Precision Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China.
| | - Yaoyi Xiong
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Mengxue Yu
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resource Preservation Center of Hubei Province, Wuhan, China
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
| | - Fenfang Zhou
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Kaiyu Qian
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resource Preservation Center of Hubei Province, Wuhan, China
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
- Laboratory of Precision Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Gang Wang
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resource Preservation Center of Hubei Province, Wuhan, China
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
- Laboratory of Precision Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yu Xiao
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Department of Biological Repositories, Zhongnan Hospital of Wuhan University, Wuhan, China
- Human Genetic Resource Preservation Center of Hubei Province, Wuhan, China
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China
- Laboratory of Precision Medicine, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Xinghuan Wang
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, China.
- Wuhan Research Center for Infectious Diseases and Cancer, Chinese Academy of Medical Sciences, Wuhan, China.
- Medical Research Institute, Wuhan University, Wuhan, China.
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56
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Zhang Y, De Laurentiis E, Bohnsack KE, Wahlig M, Ranjan N, Gruseck S, Hackert P, Wölfle T, Rodnina MV, Schwappach B, Rospert S. Ribosome-bound Get4/5 facilitates the capture of tail-anchored proteins by Sgt2 in yeast. Nat Commun 2021; 12:782. [PMID: 33542241 PMCID: PMC7862611 DOI: 10.1038/s41467-021-20981-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 01/05/2021] [Indexed: 02/03/2023] Open
Abstract
The guided entry of tail-anchored proteins (GET) pathway assists in the posttranslational delivery of tail-anchored proteins, containing a single C-terminal transmembrane domain, to the ER. Here we uncover how the yeast GET pathway component Get4/5 facilitates capture of tail-anchored proteins by Sgt2, which interacts with tail-anchors and hands them over to the targeting component Get3. Get4/5 binds directly and with high affinity to ribosomes, positions Sgt2 close to the ribosomal tunnel exit, and facilitates the capture of tail-anchored proteins by Sgt2. The contact sites of Get4/5 on the ribosome overlap with those of SRP, the factor mediating cotranslational ER-targeting. Exposure of internal transmembrane domains at the tunnel exit induces high-affinity ribosome binding of SRP, which in turn prevents ribosome binding of Get4/5. In this way, the position of a transmembrane domain within nascent ER-targeted proteins mediates partitioning into either the GET or SRP pathway directly at the ribosomal tunnel exit. The guided entry of tail-anchored proteins (GET) pathway assists in the delivery of such proteins to the ER. Here, the authors reveal that the pathway components Get4/5 probe a region near the ribosomal exit tunnel. Upon emergence of a client protein, Get4/5 recruits Sgt2 and initiates the targeting phase of the pathway.
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Affiliation(s)
- Ying Zhang
- Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Evelina De Laurentiis
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Göttingen, Germany
| | - Katherine E Bohnsack
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Mascha Wahlig
- Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Namit Ranjan
- Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Simon Gruseck
- Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Philipp Hackert
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Tina Wölfle
- Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany
| | - Marina V Rodnina
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Göttingen, Germany.,Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany. .,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), Göttingen, Germany.
| | - Sabine Rospert
- Institute of Biochemistry and Molecular Biology, University of Freiburg, Freiburg, Germany. .,BIOSS Centre for Biological Signaling Studies, University of Freiburg, Freiburg, Germany.
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57
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Wang L, Ye Y. Clearing Traffic Jams During Protein Translocation Across Membranes. Front Cell Dev Biol 2021; 8:610689. [PMID: 33490075 PMCID: PMC7820333 DOI: 10.3389/fcell.2020.610689] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 11/27/2020] [Indexed: 11/13/2022] Open
Abstract
Protein translocation across membranes is a critical facet of protein biogenesis in compartmentalized cells as proteins synthesized in the cytoplasm often need to traverse across lipid bilayers via proteinaceous channels to reach their final destinations. It is well established that protein biogenesis is tightly linked to various protein quality control processes, which monitor errors in protein folding, modification, and localization. However, little is known about how cells cope with translocation defective polypeptides that clog translocation channels (translocons) during protein translocation. This review summarizes recent studies, which collectively reveal a set of translocon-associated quality control strategies for eliminating polypeptides stuck in protein-conducting channels in the endoplasmic reticulum and mitochondria.
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Affiliation(s)
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
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58
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Lin KF, Fry MY, Saladi SM, Clemons WM. Molecular basis of tail-anchored integral membrane protein recognition by the cochaperone Sgt2. J Biol Chem 2021; 296:100441. [PMID: 33610544 PMCID: PMC8010706 DOI: 10.1016/j.jbc.2021.100441] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/04/2021] [Accepted: 02/17/2021] [Indexed: 02/08/2023] Open
Abstract
The targeting and insertion of tail-anchored (TA) integral membrane proteins (IMPs) into the correct membrane is critical for cellular homeostasis. The fungal protein Sgt2, and its human homolog SGTA, is the entry point for clients to the guided entry of tail-anchored protein (GET) pathway, which targets endoplasmic reticulum-bound TA IMPs. Consisting of three structurally independent domains, the C terminus of Sgt2 binds to the hydrophobic transmembrane domain (TMD) of clients. However, the exact binding interface within Sgt2 and molecular details that underlie its binding mechanism and client preference are not known. Here, we reveal the mechanism of Sgt2 binding to hydrophobic clients, including TA IMPs. Through sequence analysis, biophysical characterization, and a series of capture assays, we establish that the Sgt2 C-terminal domain is flexible but conserved and sufficient for client binding. A molecular model for this domain reveals a helical hand forming a hydrophobic groove approximately 15 Å long that is consistent with our observed higher affinity for client TMDs with a hydrophobic face and a minimal length of 11 residues. This work places Sgt2 into a broader family of TPR-containing cochaperone proteins, demonstrating structural and sequence-based similarities to the DP domains in the yeast Hsp90 and Hsp70 coordinating protein, Sti1.
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Affiliation(s)
- Ku-Feng Lin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - Michelle Y Fry
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - Shyam M Saladi
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA
| | - William M Clemons
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, USA.
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59
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Wang S, Wang T, Wang L, Zhong L, Li K. Overexpression of RNF126 Promotes the Development of Colorectal Cancer via Enhancing p53 Ubiquitination and Degradation. Onco Targets Ther 2020; 13:10917-10929. [PMID: 33149608 PMCID: PMC7604871 DOI: 10.2147/ott.s271855] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 09/27/2020] [Indexed: 12/23/2022] Open
Abstract
Background RING finger protein 126 (RNF126), as a novel E3 ubiquitin ligase, plays an oncogenic role in several solid cancers. But its potential role in colorectal cancer (CRC) that harbored 50% mutant p53, to our knowledge, is rarely reported. Materials and Methods We investigated the clinical significance and relationship of RNF126 and p53 in CRC tissues and cells. Meanwhile, WB, qRT-PCR, co-IP, MTT, and transwell were used to investigate the function and molecular mechanism of RNF126 in regulating malignant biology in vitro. Results RNF126 was overexpressed in human CRC specimens, which was tightly associated with tumor size (P=0.021), T stage (P=0.030), lymph node metastasis (P=0.006), TNM stage (P=0.001), and the poor survival (P=0.003) of CRC patients. RNF126 had no association with p53 mutation in CRC specimens, and in p53 mutant Colo-205 and SW620 cells. However, in p53 wildtype HCT116 and HCT-8 cells, RNF126 silencing upregulated p53 and p21 but inhibited Rb phosphorylation at Serine 780 (pRb), which was inhibited by p53siRNA. Conversely, RNF126 overexpression downregulated p53 and p21 but promoted pRb expression, which was reversed by a classic proteasome inhibitor, MG132. However, the mRNA levels of above target genes were unchanged, implying a ubiquitination dependent post-translational modification involving in above regulation. Meanwhile, RNF126 was co-immunoprecipitated with p53 and p21 to form a triple complex. RNF126 silencing and overexpression inhibited and promoted p53 ubiquitination and degradation in vitro, respectively. In addition, p53siRNA reversed RNF126 silencing-inhibited cell proliferation, drug resistance, and cell mobility in HCT116 cells. Conversely, MG132 inhibited RNF126 overexpression-promoted above cell biology in HCT-8 cells. Conclusion Overexpression of RNF126 was remarkably associated with multiple advanced clinical characters of CRC patients independent of mutant p53. RNF126 promotes cell proliferation, mobility, and drug resistance in CRC via enhancing p53 ubiquitination and degradation.
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Affiliation(s)
- Shiyang Wang
- Department of Geriatric Surgery, The First Hospital, China Medical University, Shenyang 110001, People's Republic of China.,Department of Surgical Oncology, The First Hospital, China Medical University, Shenyang 110001, People's Republic of China
| | - Tianlong Wang
- Department of Geriatric Surgery, The First Hospital, China Medical University, Shenyang 110001, People's Republic of China
| | - Li Wang
- Department of Geriatric Surgery, The First Hospital, China Medical University, Shenyang 110001, People's Republic of China
| | - Liansheng Zhong
- Department of Bioinformatics, College of Life Science, China Medical University, Shenyang 110001, People's Republic of China
| | - Kai Li
- Department of Surgical Oncology, The First Hospital, China Medical University, Shenyang 110001, People's Republic of China
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60
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Itakura E, Chiba M, Murata T, Matsuura A. Heparan sulfate is a clearance receptor for aberrant extracellular proteins. J Cell Biol 2020; 219:133807. [PMID: 32211892 PMCID: PMC7054991 DOI: 10.1083/jcb.201911126] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 01/13/2023] Open
Abstract
The accumulation of aberrant proteins leads to various neurodegenerative disorders. Mammalian cells contain several intracellular protein degradation systems, including autophagy and proteasomal systems, that selectively remove aberrant intracellular proteins. Although mammals contain not only intracellular but also extracellular proteins, the mechanism underlying the quality control of aberrant extracellular proteins is poorly understood. Here, using a novel quantitative fluorescence assay and genome-wide CRISPR screening, we identified the receptor-mediated degradation pathway by which misfolded extracellular proteins are selectively captured by the extracellular chaperone Clusterin and undergo endocytosis via the cell surface heparan sulfate (HS) receptor. Biochemical analyses revealed that positively charged residues on Clusterin electrostatically interact with negatively charged HS. Furthermore, the Clusterin-HS pathway facilitates the degradation of amyloid β peptide and diverse leaked cytosolic proteins in extracellular space. Our results identify a novel protein quality control system for preserving extracellular proteostasis and highlight its role in preventing diseases associated with aberrant extracellular proteins.
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Affiliation(s)
- Eisuke Itakura
- Department of Biology, Graduate School of Science and Engineering, Chiba University, Chiba, Japan
| | - Momoka Chiba
- Department of Biology, Faculty of Science, Chiba University, Chiba, Japan
| | - Takeshi Murata
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Akira Matsuura
- Department of Biology, Graduate School of Science and Engineering, Chiba University, Chiba, Japan
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61
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Off and On Again: De- and Reubiquitination during Membrane Protein Degradation. Mol Cell 2020; 79:203-204. [PMID: 32679074 DOI: 10.1016/j.molcel.2020.06.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In this issue of Molecular Cell, Hu et al. (2020) show that the cytosolic E3 ligase RNF126 reubiquitinates membrane proteins after their extraction from the membrane of the endoplasmic reticulum to target them for proteasomal degradation.
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62
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Tambe MA, Ng BG, Shimada S, Wolfe LA, Adams DR, Gahl WA, Bamshad MJ, Nickerson DA, Malicdan MC, Freeze HH. Mutations in GET4 disrupt the transmembrane domain recognition complex pathway. J Inherit Metab Dis 2020; 43:1037-1045. [PMID: 32395830 PMCID: PMC7508799 DOI: 10.1002/jimd.12249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/21/2020] [Accepted: 05/07/2020] [Indexed: 01/06/2023]
Abstract
The transmembrane domain recognition complex (TRC) targets cytoplasmic C-terminal tail-anchored (TA) proteins to their respective membranes in the endoplasmic reticulum (ER), Golgi, and mitochondria. It is composed of three proteins, GET4, BAG6, and GET5. We identified an individual with compound heterozygous missense variants (p.Arg122His, p.Ile279Met) in GET4 that reduced all three TRC proteins by 70% to 90% in his fibroblasts, suggesting a possible defect in TA protein targeting. He presented with global developmental delay, intellectual disabilities, seizures, facial dysmorphism, and delayed bone age. We found the TA protein, syntaxin 5, is poorly targeted to Golgi membranes compared to normal controls. Since GET4 regulates ER to Golgi transport, we hypothesized that such transport would be disrupted in his fibroblasts, and discovered that retrograde (but not anterograde) transport was significantly reduced. Despite reduction in the three TRC proteins, their mRNA levels were unchanged, suggesting increased degradation in patient fibroblasts. Treating fibroblasts with the FDA-approved proteasome inhibitor, bortezomib (10 nM), restored syntaxin 5 localization and nearly normalized the levels of all three TRC proteins. Our study identifies the first individual with GET4 mutations.
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Affiliation(s)
- Mitali A. Tambe
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Bobby G. Ng
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Shino Shimada
- Undiagnosed Diseases Program, National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), Bethesda, MD 20892, USA; Common Fund, Office of the Director, NIH, Bethesda, MD 20892-1851, USA
| | - Lynne A. Wolfe
- Undiagnosed Diseases Program, National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), Bethesda, MD 20892, USA; Common Fund, Office of the Director, NIH, Bethesda, MD 20892-1851, USA
| | - David R. Adams
- Undiagnosed Diseases Program, National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), Bethesda, MD 20892, USA; Common Fund, Office of the Director, NIH, Bethesda, MD 20892-1851, USA
- Section of Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, 10 Center Drive, Bldg. 10, Rm 10C107, MSC1851, Bethesda, MD 20892-1851, USA
| | | | - William A. Gahl
- Undiagnosed Diseases Program, National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), Bethesda, MD 20892, USA; Common Fund, Office of the Director, NIH, Bethesda, MD 20892-1851, USA
- Section of Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, 10 Center Drive, Bldg. 10, Rm 10C107, MSC1851, Bethesda, MD 20892-1851, USA
| | - Michael J. Bamshad
- Department of Pediatrics, University of Washington Seattle, Washington
- Department of Genome Sciences, University of Washington Seattle, Washington
| | | | | | - May C.V. Malicdan
- Undiagnosed Diseases Program, National Human Genome Research Institute (NHGRI), National Institutes of Health (NIH), Bethesda, MD 20892, USA; Common Fund, Office of the Director, NIH, Bethesda, MD 20892-1851, USA
- Section of Human Biochemical Genetics, Medical Genetics Branch, NHGRI, NIH, 10 Center Drive, Bldg. 10, Rm 10C107, MSC1851, Bethesda, MD 20892-1851, USA
| | - Hudson H. Freeze
- Human Genetics Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037, USA
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Abildgaard AB, Gersing SK, Larsen-Ledet S, Nielsen SV, Stein A, Lindorff-Larsen K, Hartmann-Petersen R. Co-Chaperones in Targeting and Delivery of Misfolded Proteins to the 26S Proteasome. Biomolecules 2020; 10:E1141. [PMID: 32759676 PMCID: PMC7463752 DOI: 10.3390/biom10081141] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/31/2020] [Accepted: 08/02/2020] [Indexed: 12/11/2022] Open
Abstract
Protein homeostasis (proteostasis) is essential for the cell and is maintained by a highly conserved protein quality control (PQC) system, which triages newly synthesized, mislocalized and misfolded proteins. The ubiquitin-proteasome system (UPS), molecular chaperones, and co-chaperones are vital PQC elements that work together to facilitate degradation of misfolded and toxic protein species through the 26S proteasome. However, the underlying mechanisms are complex and remain partly unclear. Here, we provide an overview of the current knowledge on the co-chaperones that directly take part in targeting and delivery of PQC substrates for degradation. While J-domain proteins (JDPs) target substrates for the heat shock protein 70 (HSP70) chaperones, nucleotide-exchange factors (NEFs) deliver HSP70-bound substrates to the proteasome. So far, three NEFs have been established in proteasomal delivery: HSP110 and the ubiquitin-like (UBL) domain proteins BAG-1 and BAG-6, the latter acting as a chaperone itself and carrying its substrates directly to the proteasome. A better understanding of the individual delivery pathways will improve our ability to regulate the triage, and thus regulate the fate of aberrant proteins involved in cell stress and disease, examples of which are given throughout the review.
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Affiliation(s)
- Amanda B. Abildgaard
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sarah K. Gersing
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sven Larsen-Ledet
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Sofie V. Nielsen
- Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (S.V.N.); (A.S.)
| | - Amelie Stein
- Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (S.V.N.); (A.S.)
| | - Kresten Lindorff-Larsen
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
| | - Rasmus Hartmann-Petersen
- Department of Biology, The Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark; (A.B.A.); (S.K.G.); (S.L.-L.); (K.L.-L.)
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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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65
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Zhang R, Liu W, Sun J, Kong Y, Chen C. Roles of RNF126 and BCA2 E3 ubiquitin ligases in DNA damage repair signaling and targeted cancer therapy. Pharmacol Res 2020; 155:104748. [DOI: 10.1016/j.phrs.2020.104748] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 01/16/2023]
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66
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Tim-3: A co-receptor with diverse roles in T cell exhaustion and tolerance. Semin Immunol 2020; 42:101302. [PMID: 31604535 DOI: 10.1016/j.smim.2019.101302] [Citation(s) in RCA: 90] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 08/30/2019] [Indexed: 12/13/2022]
Abstract
T cell inhibitory co-receptors play a crucial role in maintaining the balance between physiologic immune responses and maladaptive ones. T cell immunoglobulin and mucin domain-containing-3 (Tim-3) is a unique inhibitory co-receptor in that its expression is chiefly restricted to interferon (IFN)γ-producing CD4+ and CD8+ T cells. Early reports firmly established its importance in maintaining peripheral tolerance in transplantation and autoimmunity. However, it has become increasingly clear that Tim-3 expression on T cells, together with other check-point molecules, in chronic infections and cancers can hinder productive immune responses. In this review, we outline what is currently known about the regulation of Tim-3 expression, its ligands and signaling. We discuss both its salutary and deleterious function in immune disorders, as well as the T cell-extrinsic and -intrinsic factors that regulate its function.
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67
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Leznicki P, High S. SGTA associates with nascent membrane protein precursors. EMBO Rep 2020; 21:e48835. [PMID: 32216016 PMCID: PMC7202230 DOI: 10.15252/embr.201948835] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 02/25/2020] [Accepted: 02/28/2020] [Indexed: 01/15/2023] Open
Abstract
The endoplasmic reticulum (ER) is a major site for membrane protein synthesis in eukaryotes. The majority of integral membrane proteins are delivered to the ER membrane via the co‐translational, signal recognition particle (SRP)‐dependent route. However, tail‐anchored proteins employ an alternative, post‐translational route(s) that relies on distinct factors such as a cytosolic protein quality control component, SGTA. We now show that SGTA is selectively recruited to ribosomes synthesising a diverse range of membrane proteins, suggesting that its biosynthetic client base also includes precursors on the co‐translational ER delivery pathway. Strikingly, SGTA is recruited to nascent membrane proteins before their transmembrane domain emerges from the ribosome. Hence, SGTA is ideally placed to capture these aggregation prone regions shortly after their synthesis. For nascent membrane proteins on the co‐translational pathway, SGTA complements the role of SRP by reducing the co‐translational ubiquitination of clients with multiple hydrophobic signal sequences. On this basis, we propose that SGTA acts to mask specific transmembrane domains located in complex membrane proteins until they can engage the ER translocon and become membrane inserted.
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Affiliation(s)
- Pawel Leznicki
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Stephen High
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
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Kim SY, Kim HJ, Kim HJ, Kim CH. Non-Thermal Plasma Induces Antileukemic Effect Through mTOR Ubiquitination. Cells 2020; 9:cells9030595. [PMID: 32131492 PMCID: PMC7140413 DOI: 10.3390/cells9030595] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/24/2020] [Accepted: 02/28/2020] [Indexed: 12/20/2022] Open
Abstract
Non-thermal plasma (NTP) has been studied as a novel therapeutic tool for cancer that does not damage healthy cells. In this study, we show that NTP-treated solutions (NTS) can induce death in various leukemia cells through mechanistic target of rapamycin (mTOR) ubiquitination. Previously, we manufactured and demonstrated the efficacy of NTS in solid cancers. NTS did not exhibit any deleterious side effects, such as acute death or weight loss in nude mice. In the present study, NTS induced cell death in myeloid leukemia cells, including acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). We found that mTOR was downregulated in NTS-treated cells via the ubiquitin-proteasome system (UPS). We also identified ‘really interesting new gene’ finger protein 126 (RNF126) as a novel binding protein for mTOR through protein arrays and determined the role of E3 ligase in NTS-induced mTOR ubiquitination. NTS-derived reactive oxygen species (ROS) affected RNF126 expression and lysosomal dysfunction. These findings suggest that NTS has potential antileukemic effects through RNF126-mediated mTOR ubiquitination with no deleterious side effects. Thus, NTS may represent a new therapeutic method for chemotherapy-resistant leukemia.
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Affiliation(s)
- Sun-Yong Kim
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea; (S.-Y.K.); (H.J.K.); (H.J.K.)
- Oncoprotein Modification and Regulation Research Center, Ajou University, Suwon 16499, Korea
| | - Hyo Jeong Kim
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea; (S.-Y.K.); (H.J.K.); (H.J.K.)
- Oncoprotein Modification and Regulation Research Center, Ajou University, Suwon 16499, Korea
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea
| | - Haeng Jun Kim
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea; (S.-Y.K.); (H.J.K.); (H.J.K.)
- Oncoprotein Modification and Regulation Research Center, Ajou University, Suwon 16499, Korea
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea
| | - Chul-Ho Kim
- Department of Otolaryngology, Ajou University School of Medicine, Suwon 16499, Korea; (S.-Y.K.); (H.J.K.); (H.J.K.)
- Oncoprotein Modification and Regulation Research Center, Ajou University, Suwon 16499, Korea
- Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea
- Correspondence: ; Tel.: +82-31-219-5269
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69
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PAQR9 Modulates BAG6-mediated protein quality control of mislocalized membrane proteins. Biochem J 2020; 477:477-489. [PMID: 31904842 DOI: 10.1042/bcj20190620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 12/24/2019] [Accepted: 01/06/2020] [Indexed: 11/17/2022]
Abstract
Protein quality control is crucial for maintaining cellular homeostasis and its dysfunction is closely linked to human diseases. The post-translational protein quality control machinery mainly composed of BCL-2-associated athanogene 6 (BAG6) is responsible for triage of mislocalized membrane proteins (MLPs). However, it is unknown how the BAG6-mediated degradation of MLPs is regulated. We report here that PAQR9, a member of the Progesterone and AdipoQ receptor (PAQR) family, is able to modulate BAG6-mediated triage of MLPs. Analysis with mass spectrometry identified that BAG6 is one of the major proteins interacting with PAQR9 and such interaction is confirmed by co-immunoprecipitation and co-localization assays. The protein degradation rate of representative MLPs is accelerated by PAQR9 knockdown. Consistently, the polyubiquitination of MLPs is enhanced by PAQR9 knockdown. PAQR9 binds to the DUF3538 domain within the proline-rich stretch of BAG6. PAQR9 reduces the binding of MLPs to BAG6 in a DUF3538 domain-dependent manner. Taken together, our results indicate that PAQR9 plays a role in the regulation of protein quality control of MLPs via affecting the interaction of BAG6 with membrane proteins.
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70
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Abstract
Due to their topology tail-anchored (TA) proteins must target to the membrane independently of the co-translational route defined by the signal sequence recognition particle (SRP), its receptor and the translocon Sec61. More than a decade of work has extensively characterized a highly conserved pathway, the yeast GET or mammalian TRC40 pathway, which is capable of countering the biogenetic challenge posed by the C-terminal TA anchor. In this review we briefly summarize current models of this targeting route and focus on emerging aspects such as the intricate interplay with the proteostatic network of cells and with other targeting pathways. Importantly, we consider the lessons provided by the in vivo analysis of the pathway in different model organisms and by the consideration of its full client spectrum in more recent studies. This analysis of the state of the field highlights directions in which the current models may be experimentally probed and conceptually extended.
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Affiliation(s)
- Nica Borgese
- Institute of Neuroscience and BIOMETRA Department, Consiglio Nazionale delle Ricerche and Università degli Studi di Milano, via Vanvitelli 32, 20129, Milan, Italy.
| | - Javier Coy-Vergara
- Department of Molecular Biology, University of Göttingen Medical Centre, Humboldtallee 23, 37073, Göttingen, Germany
| | - Sara Francesca Colombo
- Institute of Neuroscience and BIOMETRA Department, Consiglio Nazionale delle Ricerche and Università degli Studi di Milano, via Vanvitelli 32, 20129, Milan, Italy
| | - Blanche Schwappach
- Department of Molecular Biology, University of Göttingen Medical Centre, Humboldtallee 23, 37073, Göttingen, Germany.
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71
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Hegde RS, Zavodszky E. Recognition and Degradation of Mislocalized Proteins in Health and Disease. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a033902. [PMID: 30833453 DOI: 10.1101/cshperspect.a033902] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A defining feature of eukaryotic cells is the segregation of complex biochemical processes among different intracellular compartments. The protein targeting, translocation, and trafficking pathways that sustain compartmentalization must recognize a diverse range of clients via degenerate signals. This recognition is imperfect, resulting in polypeptides at incorrect cellular locations. Cells have evolved mechanisms to selectively recognize mislocalized proteins and triage them for degradation or rescue. These spatial quality control pathways maintain cellular protein homeostasis, become especially important during organelle stress, and might contribute to disease when they are impaired or overwhelmed.
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Affiliation(s)
- Ramanujan S Hegde
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Eszter Zavodszky
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
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72
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Shcherbakov D, Teo Y, Boukari H, Cortes-Sanchon A, Mantovani M, Osinnii I, Moore J, Juskeviciene R, Brilkova M, Duscha S, Kumar HS, Laczko E, Rehrauer H, Westhof E, Akbergenov R, Böttger EC. Ribosomal mistranslation leads to silencing of the unfolded protein response and increased mitochondrial biogenesis. Commun Biol 2019; 2:381. [PMID: 31637312 PMCID: PMC6797716 DOI: 10.1038/s42003-019-0626-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/20/2019] [Indexed: 12/19/2022] Open
Abstract
Translation fidelity is the limiting factor in the accuracy of gene expression. With an estimated frequency of 10-4, errors in mRNA decoding occur in a mostly stochastic manner. Little is known about the response of higher eukaryotes to chronic loss of ribosomal accuracy as per an increase in the random error rate of mRNA decoding. Here, we present a global and comprehensive picture of the cellular changes in response to translational accuracy in mammalian ribosomes impaired by genetic manipulation. In addition to affecting established protein quality control pathways, such as elevated transcript levels for cytosolic chaperones, activation of the ubiquitin-proteasome system, and translational slowdown, ribosomal mistranslation led to unexpected responses. In particular, we observed increased mitochondrial biogenesis associated with import of misfolded proteins into the mitochondria and silencing of the unfolded protein response in the endoplasmic reticulum.
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Affiliation(s)
- Dmitri Shcherbakov
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Youjin Teo
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Heithem Boukari
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Adrian Cortes-Sanchon
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Matilde Mantovani
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Ivan Osinnii
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - James Moore
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Reda Juskeviciene
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Margarita Brilkova
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Stefan Duscha
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | | | - Endre Laczko
- Functional Genomics Center Zurich, ETH Zürich und Universität Zürich, 8057 Zurich, Switzerland
| | - Hubert Rehrauer
- Functional Genomics Center Zurich, ETH Zürich und Universität Zürich, 8057 Zurich, Switzerland
| | - Eric Westhof
- Institut de Biologie Moléculaire et Cellulaire du CNRS, Université de Strasbourg, 67084 Strasbourg, France
| | - Rashid Akbergenov
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
| | - Erik C. Böttger
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zurich, Switzerland
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Abstract
One-fourth of eukaryotic genes code for integral membrane proteins, nearly all of which are inserted and assembled at the endoplasmic reticulum (ER). The defining feature of membrane proteins is one or more transmembrane domains (TMDs). During membrane protein biogenesis, TMDs are selectively recognized, shielded, and chaperoned into the lipid bilayer, where they often assemble with other TMDs. If maturation fails, exposed TMDs serve as a cue for engagement of degradation pathways. Thus, TMD-recognition factors in the cytosol and ER are essential for membrane protein biogenesis and quality control. Here, we discuss the growing assortment of cytosolic and membrane-embedded TMD-recognition factors, the pathways within which they operate, and mechanistic principles of recognition.
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74
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Kamikubo K, Kato H, Kioka H, Yamazaki S, Tsukamoto O, Nishida Y, Asano Y, Imamura H, Kawahara H, Shintani Y, Takashima S. A molecular triage process mediated by RING finger protein 126 and BCL2-associated athanogene 6 regulates degradation of G 0/G 1 switch gene 2. J Biol Chem 2019; 294:14562-14573. [PMID: 31371451 DOI: 10.1074/jbc.ra119.008544] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/19/2019] [Indexed: 12/29/2022] Open
Abstract
Oxidative phosphorylation generates most of the ATP in respiring cells. ATP is an essential energy source, especially in cardiomyocytes because of their continuous contraction and relaxation. Previously, we reported that G0/G1 switch gene 2 (G0S2) positively regulates mitochondrial ATP production by interacting with FOF1-ATP synthase. G0S2 overexpression mitigates ATP decline in cardiomyocytes and strongly increases their hypoxic tolerance during ischemia. Here, we show that G0S2 protein undergoes proteasomal degradation via a cytosolic molecular triage system and that inhibiting this process increases mitochondrial ATP production in hypoxia. First, we performed screening with a library of siRNAs targeting ubiquitin-related genes and identified RING finger protein 126 (RNF126) as an E3 ligase involved in G0S2 degradation. RNF126-deficient cells exhibited prolonged G0S2 protein turnover and reduced G0S2 ubiquitination. BCL2-associated athanogene 6 (BAG6), involved in the molecular triage of nascent membrane proteins, enhanced RNF126-mediated G0S2 ubiquitination both in vitro and in vivo Next, we found that Glu-44 in the hydrophobic region of G0S2 acts as a degron necessary for G0S2 polyubiquitination and proteasomal degradation. Because this degron was required for an interaction of G0S2 with BAG6, an alanine-replaced G0S2 mutant (E44A) escaped degradation. In primary cultured cardiomyocytes, both overexpression of the G0S2 E44A mutant and RNF126 knockdown effectively attenuated ATP decline under hypoxic conditions. We conclude that the RNF126/BAG6 complex contributes to G0S2 degradation and that interventions to prevent G0S2 degradation may offer a therapeutic strategy for managing ischemic diseases.
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Affiliation(s)
- Kenta Kamikubo
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan
| | - Hisakazu Kato
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan
| | - Hidetaka Kioka
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Satoru Yamazaki
- Department of Cell Biology, National Cerebral and Cardiovascular Center, Suita, Osaka 565-8565, Japan
| | - Osamu Tsukamoto
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan
| | - Yuya Nishida
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan.,Japan Science and Technology Agency-Core Research for Evolutional Science and Technology (CREST), Kawaguchi, Saitama 332-0012, Japan
| | - Yoshihiro Asano
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Hiromi Imamura
- Laboratory of Functional Biology, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan
| | - Hiroyuki Kawahara
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, 192-0397, Japan
| | - Yasunori Shintani
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan
| | - Seiji Takashima
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan .,Japan Science and Technology Agency-Core Research for Evolutional Science and Technology (CREST), Kawaguchi, Saitama 332-0012, Japan
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75
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Hayashishita M, Kawahara H, Yokota N. BAG6 deficiency induces mis-distribution of mitochondrial clusters under depolarization. FEBS Open Bio 2019; 9:1281-1291. [PMID: 31125507 PMCID: PMC6609563 DOI: 10.1002/2211-5463.12677] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 04/16/2019] [Accepted: 05/22/2019] [Indexed: 01/09/2023] Open
Abstract
Accumulation of damaged mitochondria is implicated in a number of neurodegenerative disorders, including Parkinson's disease. Therefore, the machinery for mitochondrial quality control is important for the prevention of such diseases. It has been reported that Parkin‐ and p62/sequestosome 1 (SQSTM1)‐mediated clustering and subsequent elimination of damaged mitochondria (termed mitophagy) are critical for maintaining the quality of mitochondria under stress induced by uncoupling agents such as carbonyl cyanide m‐chlorophenyl hydrazone. However, the molecular mechanisms underlying mitochondrial translocation to the perinuclear region during mitophagy have not been adequately addressed to date. In this study, we found that BCL2‐associated athanogene 6 (BAG6; also known as BAT3 or Scythe) is required for this process. Indeed, RNA interference‐mediated depletion of endogenous BAG6 prevented Parkin‐dependent relocalization of mitochondrial clusters to the perinuclear cytoplasmic region, whereas BAG6 knockdown did not affect the translocation of Parkin and p62/SQSTM1 to the depolarized mitochondria and subsequent aggregation. These results suggest that BAG6 is essential for cytoplasmic redistribution, but not for clustering, of damaged mitochondria.
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Affiliation(s)
- Mizuki Hayashishita
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Japan
| | - Hiroyuki Kawahara
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Japan
| | - Naoto Yokota
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Japan
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76
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Fregno I, Molinari M. Proteasomal and lysosomal clearance of faulty secretory proteins: ER-associated degradation (ERAD) and ER-to-lysosome-associated degradation (ERLAD) pathways. Crit Rev Biochem Mol Biol 2019; 54:153-163. [PMID: 31084437 DOI: 10.1080/10409238.2019.1610351] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
About 40% of the eukaryotic cell's proteins are inserted co- or post-translationally in the endoplasmic reticulum (ER), where they attain the native structure under the assistance of resident molecular chaperones and folding enzymes. Subsequently, these proteins are secreted from cells or are transported to their sites of function at the plasma membrane or in organelles of the secretory and endocytic compartments. Polypeptides that are not delivered within the ER (mis-localized proteins, MLPs) are rapidly destroyed by cytosolic proteasomes, with intervention of the membrane protease ZMPSTE24 if they remained trapped in the SEC61 translocation machinery. Proteins that enter the ER, but fail to attain the native structure are rapidly degraded to prevent toxic accumulation of aberrant gene products. The ER does not contain degradative devices and the majority of misfolded proteins generated in this biosynthetic compartment are dislocated across the membrane for degradation by cytosolic 26S proteasomes by mechanisms and pathways collectively defined as ER-associated degradation (ERAD). Proteins that do not engage ERAD factors, that enter aggregates or polymers, are too large, display chimico/physical features that prevent dislocation across the ER membrane (ERAD-resistant misfolded proteins) are delivered to endo-lysosome for clearance, by mechanisms and pathways collectively defined as ER-to-lysosomes-associated degradation (ERLAD). Emerging evidences lead us to propose ERLAD as an umbrella term that includes the autophagic and non-autophagic pathways activated and engaged by ERAD-resistant misfolded proteins generated in the ER for delivery to degradative endo-lysosomes.
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Affiliation(s)
- Ilaria Fregno
- a Institute for Research in Biomedicine, Faculty of Biomedical Sciences , Università della Svizzera italiana (USI) , Bellinzona , Switzerland
| | - Maurizio Molinari
- a Institute for Research in Biomedicine, Faculty of Biomedical Sciences , Università della Svizzera italiana (USI) , Bellinzona , Switzerland.,b School of Life Sciences , École Polytechnique Fédérale de Lausanne , Lausanne , Switzerland
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77
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Tran A. The N-end rule pathway and Ubr1 enforce protein compartmentalization via P2-encoded cellular location signals. J Cell Sci 2019; 132:jcs.231662. [PMID: 30940687 DOI: 10.1242/jcs.231662] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 03/22/2019] [Indexed: 12/24/2022] Open
Abstract
The Arg/N-end rule pathway and Ubr1, a ubiquitin E3 ligase conserved from yeast to humans, is involved in the degradation of misfolded proteins in the cytosol. However, the root physiological purpose of this activity is not completely understood. Through a systematic examination of single-residue P2-position mutants of misfolded proteins, and global and targeted bioinformatic analyses of the Saccharomyces cerevisiae proteome, it was determined that Ubr1 preferentially targets mistranslocated secretory and mitochondrial proteins in the cytosol. Degradation by Ubr1 is dependent on the recognition of cellular location signals that are naturally embedded into the second amino acid residue of most proteins. This P2-encoded location signaling mechanism may shed light on how Ubr1 and the N-end rule pathway are involved in neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. A corollary to this discovery is that the N-end rule pathway enforces the compartmentalization of secretory and mitochondrial proteins by degrading those that fail to reach their intended subcellular locations. The N-end rule pathway is therefore likely to have been critical to the evolution of endosymbiotic relationships that paved the way for advanced eukaryotic cellular life. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Anthony Tran
- National University of Singapore, Department of Biological Sciences, Singapore 117604
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78
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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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79
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Takahashi T, Minami S, Tsuchiya Y, Tajima K, Sakai N, Suga K, Hisanaga SI, Ohbayashi N, Fukuda M, Kawahara H. Cytoplasmic control of Rab family small GTPases through BAG6. EMBO Rep 2019; 20:embr.201846794. [PMID: 30804014 PMCID: PMC6446207 DOI: 10.15252/embr.201846794] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 01/25/2019] [Accepted: 01/29/2019] [Indexed: 11/18/2022] Open
Abstract
Rab family small GTPases are master regulators of distinct steps of intracellular vesicle trafficking in eukaryotic cells. GDP‐bound cytoplasmic forms of Rab proteins are prone to aggregation due to the exposure of hydrophobic groups but the machinery that determines the fate of Rab species in the cytosol has not been elucidated in detail. In this study, we find that BAG6 (BAT3/Scythe) predominantly recognizes a cryptic portion of GDP‐associated Rab8a, while its major GTP‐bound active form is not recognized. The hydrophobic residues of the Switch I region of Rab8a are essential for its interaction with BAG6 and the degradation of GDP‐Rab8a via the ubiquitin‐proteasome system. BAG6 prevents the excess accumulation of inactive Rab8a, whose accumulation impairs intracellular membrane trafficking. BAG6 binds not only Rab8a but also a functionally distinct set of Rab family proteins, and is also required for the correct distribution of Golgi and endosomal markers. From these observations, we suggest that Rab proteins represent a novel set of substrates for BAG6, and the BAG6‐mediated pathway is associated with the regulation of membrane vesicle trafficking events in mammalian cells.
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Affiliation(s)
- Toshiki Takahashi
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Setsuya Minami
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Yugo Tsuchiya
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Kazu Tajima
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Natsumi Sakai
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Kei Suga
- Department of Cell Physiology, Kyorin University School of Medicine, Mitaka, Japan.,Department of Chemistry, Kyorin University School of Medicine, Mitaka, Japan
| | - Shin-Ichi Hisanaga
- Laboratory of Molecular Neuroscience, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
| | - Norihiko Ohbayashi
- Department of Physiological Chemistry, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Mitsunori Fukuda
- Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Hiroyuki Kawahara
- Laboratory of Cell Biology and Biochemistry, Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
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80
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Kats I, Khmelinskii A, Kschonsak M, Huber F, Knieß RA, Bartosik A, Knop M. Mapping Degradation Signals and Pathways in a Eukaryotic N-terminome. Mol Cell 2019; 70:488-501.e5. [PMID: 29727619 DOI: 10.1016/j.molcel.2018.03.033] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 01/26/2018] [Accepted: 03/27/2018] [Indexed: 01/01/2023]
Abstract
Most eukaryotic proteins are N-terminally acetylated. This modification can be recognized as a signal for selective protein degradation (degron) by the N-end rule pathways. However, the prevalence and specificity of such degrons in the proteome are unclear. Here, by systematically examining how protein turnover is affected by N-terminal sequences, we perform a comprehensive survey of degrons in the yeast N-terminome. We find that approximately 26% of nascent protein N termini encode cryptic degrons. These degrons exhibit high hydrophobicity and are frequently recognized by the E3 ubiquitin ligase Doa10, suggesting a role in protein quality control. In contrast, N-terminal acetylation rarely functions as a degron. Surprisingly, we identify two pathways where N-terminal acetylation has the opposite function and blocks protein degradation through the E3 ubiquitin ligase Ubr1. Our analysis highlights the complexity of N-terminal degrons and argues that hydrophobicity, not N-terminal acetylation, is the predominant feature of N-terminal degrons in nascent proteins.
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Affiliation(s)
- Ilia Kats
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Anton Khmelinskii
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Marc Kschonsak
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Florian Huber
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Robert A Knieß
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Anna Bartosik
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; Deutsches Krebsforschungszentrum (DKFZ), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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81
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Benarroch R, Austin JM, Ahmed F, Isaacson RL. The roles of cytosolic quality control proteins, SGTA and the BAG6 complex, in disease. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2019; 114:265-313. [PMID: 30635083 PMCID: PMC7102839 DOI: 10.1016/bs.apcsb.2018.11.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
SGTA is a co-chaperone that, in collaboration with the complex of BAG6/UBL4A/TRC35, facilitates the biogenesis and quality control of hydrophobic proteins, protecting them from the aqueous cytosolic environment. This work includes targeting tail-anchored proteins to their resident membranes, sorting of membrane and secretory proteins that mislocalize to the cytoplasm and endoplasmic reticulum-associated degradation of misfolded proteins. Since these functions are all vital for the cell's continued proteostasis, their disruption poses a threat to the cell, with a particular risk of protein aggregation, a phenomenon that underpins many diseases. Although the specific disease implications of machinery involved in quality control of hydrophobic substrates are poorly understood, here we summarize much of the available information on this topic.
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Affiliation(s)
- Rashi Benarroch
- Department of Chemistry, King's College London, London, United Kingdom
| | - Jennifer M Austin
- Department of Chemistry, King's College London, London, United Kingdom
| | - Fahmeda Ahmed
- Department of Chemistry, King's College London, London, United Kingdom
| | - Rivka L Isaacson
- Department of Chemistry, King's College London, London, United Kingdom.
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82
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Combet S, Cousin F, Rezaei H, Noinville S. Membrane interaction of off-pathway prion oligomers and lipid-induced on-pathway intermediates during prion conversion: A clue for neurotoxicity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:514-523. [PMID: 30529078 DOI: 10.1016/j.bbamem.2018.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 11/21/2018] [Accepted: 12/04/2018] [Indexed: 12/31/2022]
Abstract
Soluble oligomers of prion proteins (PrP), produced during amyloid aggregation, have emerged as the primary neurotoxic species, instead of the fibrillar end-products, in transmissible spongiform encephalopathies. However, whether the membrane is among their direct targets, that mediate the downstream adverse effects, remains a question of debate. Recently, questions arise from the formation of membrane-active oligomeric species generated during the β-aggregation pathway, either in solution, or in lipid environment. In the present study, we characterized membrane interaction of off-pathway oligomers from recombinant prion protein generated along the amyloid aggregation and compared to lipid-induced intermediates produced during lipid-accelerated fibrillation. Using calcein-leakage assay, we show that the soluble prion oligomers are the most potent in producing leakage with negatively charged vesicles. Binding affinities, conformational states, mode of action of the different PrP assemblies were determined by thioflavin T binding-static light scattering experiments on DOPC/DOPS vesicles, as well as by FTIR-ATR spectroscopy and specular neutron reflectivity onto the corresponding supported lipid bilayers. Our results indicate that the off-pathway PrP oligomers interact with lipid membrane via a distinct mechanism, compared to the inserted lipid-induced intermediates. Thus, separate neurotoxic mechanisms could exist following the puzzling intermediates generated in the different cell compartments. These results not only reveal an important regulation of lipid membrane on PrP behavior but may also provide clues for designing stage-specific and prion-targeted therapy.
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Affiliation(s)
- Sophie Combet
- Laboratoire Léon-Brillouin, UMR 12 CEA-CNRS, Université Paris-Saclay, CEA-Saclay, F-91191 Gif-sur-Yvette CEDEX, France
| | - Fabrice Cousin
- Laboratoire Léon-Brillouin, UMR 12 CEA-CNRS, Université Paris-Saclay, CEA-Saclay, F-91191 Gif-sur-Yvette CEDEX, France
| | - Human Rezaei
- Laboratoire de Virologie et Immunologie Moléculaires, UR892, Institut National de la Recherche Agronomique (INRA), F-78352 Jouy-en-Josas, France
| | - Sylvie Noinville
- Laboratoire MONARIS, UMR 8233, Sorbonne Université, CNRS, F-75005 Paris, France.
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83
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Zhang L, Wang Z, Shi R, Zhu X, Zhou J, Peng B, Xu X. RNF126 Quenches RNF168 Function in the DNA Damage Response. GENOMICS PROTEOMICS & BIOINFORMATICS 2018; 16:428-438. [PMID: 30529286 PMCID: PMC6411902 DOI: 10.1016/j.gpb.2018.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 07/19/2018] [Accepted: 07/24/2018] [Indexed: 01/31/2023]
Abstract
DNA damage response (DDR) is essential for maintaining genome stability and protecting cells from tumorigenesis. Ubiquitin and ubiquitin-like modifications play an important role in DDR, from signaling DNA damage to mediating DNA repair. In this report, we found that the E3 ligase ring finger protein 126 (RNF126) was recruited to UV laser micro-irradiation-induced stripes in a RNF8-dependent manner. RNF126 directly interacted with and ubiquitinated another E3 ligase, RNF168. Overexpression of wild type RNF126, but not catalytically-inactive mutant RNF126 (CC229/232AA), diminished ubiquitination of H2A histone family member X (H2AX), and subsequent bleomycin-induced focus formation of total ubiquitin FK2, TP53-binding protein 1 (53BP1), and receptor-associated protein 80 (RAP80). Interestingly, both RNF126 overexpression and RNF126 downregulation compromised homologous recombination (HR)-mediated repair of DNA double-strand breaks (DSBs). Taken together, our findings demonstrate that RNF126 negatively regulates RNF168 function in DDR and its appropriate cellular expression levels are essential for HR-mediated DSB repair.
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Affiliation(s)
- Lianzhong Zhang
- College of Life Sciences, Capital Normal University, Beijing 100048, China; Faculty of Life Sciences, Tangshan Normal College, Tangshan 063000, China
| | - Zhenzhen Wang
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ruifeng Shi
- College of Life Sciences, Capital Normal University, Beijing 100048, China; Guangdong Key Laboratory for Genome Stability & Disease Prevention, Shenzhen University Health Science Center, Shenzhen 518060, China
| | - Xuefei Zhu
- Guangdong Key Laboratory for Genome Stability & Disease Prevention, Shenzhen University Health Science Center, Shenzhen 518060, China
| | - Jiahui Zhou
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Bin Peng
- Guangdong Key Laboratory for Genome Stability & Disease Prevention, Shenzhen University Health Science Center, Shenzhen 518060, China
| | - Xingzhi Xu
- College of Life Sciences, Capital Normal University, Beijing 100048, China; Guangdong Key Laboratory for Genome Stability & Disease Prevention, Shenzhen University Health Science Center, Shenzhen 518060, China.
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84
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Iruka Eliminates Dysfunctional Argonaute by Selective Ubiquitination of Its Empty State. Mol Cell 2018; 73:119-129.e5. [PMID: 30503771 DOI: 10.1016/j.molcel.2018.10.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 08/31/2018] [Accepted: 10/19/2018] [Indexed: 12/13/2022]
Abstract
MicroRNAs (miRNAs) are loaded into the Argonaute subfamily of proteins (AGO) to form an effector complex that silences target genes. Empty but not miRNA-loaded AGO is selectively degraded across species. However, the mechanism and biological significance of selective AGO degradation remain unclear. We discovered a RING-type E3 ubiquitin ligase we named Iruka (Iru), which selectively ubiquitinates the empty form of Drosophila Ago1 to trigger its degradation. Iru preferentially binds empty Ago1 and ubiquitinates Lys514 in the L2 linker, which is predicted to be inaccessible in the miRNA-loaded state. Depletion of Iru results in global impairment of miRNA-mediated silencing of target genes and in the accumulation of aberrant Ago1 that is dysfunctional for canonical protein-protein interactions and miRNA loading. Our findings reveal a sophisticated mechanism for the selective degradation of empty AGO that underlies a quality control process to ensure AGO function.
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85
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Park JH, Kang CH, Nawkar GM, Lee ES, Paeng SK, Chae HB, Chi YH, Kim WY, Yun DJ, Lee SY. EMR, a cytosolic-abundant ring finger E3 ligase, mediates ER-associated protein degradation in Arabidopsis. THE NEW PHYTOLOGIST 2018; 220:163-177. [PMID: 29932218 DOI: 10.1111/nph.15279] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 05/18/2018] [Indexed: 05/16/2023]
Abstract
Investigation of the endoplasmic reticulum-associated degradation (ERAD) system in plants led to the identification of ERAD-mediating RING finger protein (EMR) as a plant-specific ERAD E3 ligase from Arabidopsis. EMR was significantly up-regulated under endoplasmic reticulum (ER) stress conditions. The EMR protein purified from bacteria displayed high E3 ligase activity, and tobacco leaf-produced EMR mediated mildew resistance locus O-12 (MLO12) degradation in a proteasome-dependent manner. Subcellular localization and coimmunoprecipitation analyses showed that EMR forms a complex with ubiquitin-conjugating enzyme 32 (UBC32) as a cytosolic interaction partner. Mutation of EMR and RNA interference (RNAi) increased the tolerance of plants to ER stress. EMR RNAi in the bri1-5 background led to partial recovery of the brassinosteroid (BR)-insensitive phenotypes as compared with the original mutant plants and increased ER stress tolerance. The presented results suggest that EMR is involved in the plant ERAD system that affects BR signaling under ER stress conditions as a novel Arabidopsis ring finger E3 ligase mainly present in cytosol while the previously identified ERAD E3 components are typically membrane-bound proteins.
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Affiliation(s)
- Joung Hun Park
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Chang Ho Kang
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Ganesh M Nawkar
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Eun Seon Lee
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Seol Ki Paeng
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Ho Byoung Chae
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Yong Hun Chi
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Woe Yeon Kim
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
| | - Dae-Jin Yun
- Department of Biomedical Science and Engineering, Konkuk University, Seoul, 05029, Korea
| | - Sang Yeol Lee
- Division of Applied Life Sciences (BK21+) and Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, 52828, Korea
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86
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Abstract
Ubiquitylation is an essential posttranslational modification that controls cell division, differentiation, and survival in all eukaryotes. By combining multiple E3 ligases (writers), ubiquitin-binding effectors (readers), and de-ubiquitylases (erasers) with functionally distinct ubiquitylation tags, the ubiquitin system constitutes a powerful signaling network that is employed in similar ways from yeast to humans. Here, we discuss conserved principles of ubiquitin-dependent signaling that illustrate how this posttranslational modification shapes intracellular signaling networks to establish robust development and homeostasis throughout the eukaryotic kingdom.
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Affiliation(s)
- Eugene Oh
- Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA; .,Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
| | - David Akopian
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
| | - Michael Rape
- Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA; .,Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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87
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Abstract
The billions of proteins inside a eukaryotic cell are organized among dozens of sub-cellular compartments, within which they are further organized into protein complexes. The maintenance of both levels of organization is crucial for normal cellular function. Newly made proteins that fail to be segregated to the correct compartment or assembled into the appropriate complex are defined as orphans. In this review, we discuss the challenges faced by a cell of minimizing orphaned proteins, the quality control systems that recognize orphans, and the consequences of excess orphans for protein homeostasis and disease.
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88
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Martínez-Lumbreras S, Krysztofinska EM, Thapaliya A, Spilotros A, Matak-Vinkovic D, Salvadori E, Roboti P, Nyathi Y, Muench JH, Roessler MM, Svergun DI, High S, Isaacson RL. Structural complexity of the co-chaperone SGTA: a conserved C-terminal region is implicated in dimerization and substrate quality control. BMC Biol 2018; 16:76. [PMID: 29996828 PMCID: PMC6042327 DOI: 10.1186/s12915-018-0542-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 06/20/2018] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Protein quality control mechanisms are essential for cell health and involve delivery of proteins to specific cellular compartments for recycling or degradation. In particular, stray hydrophobic proteins are captured in the aqueous cytosol by a co-chaperone, the small glutamine-rich, tetratricopeptide repeat-containing protein alpha (SGTA), which facilitates the correct targeting of tail-anchored membrane proteins, as well as the sorting of membrane and secretory proteins that mislocalize to the cytosol and endoplasmic reticulum-associated degradation. Full-length SGTA has an unusual elongated dimeric structure that has, until now, evaded detailed structural analysis. The C-terminal region of SGTA plays a key role in binding a broad range of hydrophobic substrates, yet in contrast to the well-characterized N-terminal and TPR domains, there is a lack of structural information on the C-terminal domain. In this study, we present new insights into the conformation and organization of distinct domains of SGTA and show that the C-terminal domain possesses a conserved region essential for substrate processing in vivo. RESULTS We show that the C-terminal domain region is characterized by α-helical propensity and an intrinsic ability to dimerize independently of the N-terminal domain. Based on the properties of different regions of SGTA that are revealed using cell biology, NMR, SAXS, Native MS, and EPR, we observe that its C-terminal domain can dimerize in the full-length protein and propose that this reflects a closed conformation of the substrate-binding domain. CONCLUSION Our results provide novel insights into the structural complexity of SGTA and provide a new basis for mechanistic studies of substrate binding and release at the C-terminal region.
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Affiliation(s)
| | - Ewelina M Krysztofinska
- Department of Chemistry, King's College London, Britannia House, Trinity Street, London, SE1 1DB, UK
| | - Arjun Thapaliya
- Department of Chemistry, King's College London, Britannia House, Trinity Street, London, SE1 1DB, UK
| | - Alessandro Spilotros
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestrasse 85, 22603, Hamburg, Germany
| | - Dijana Matak-Vinkovic
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Enrico Salvadori
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
- London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK
| | - Peristera Roboti
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Yvonne Nyathi
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
- Present Address: School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, UK
| | - Janina H Muench
- Department of Chemistry, King's College London, Britannia House, Trinity Street, London, SE1 1DB, UK
| | - Maxie M Roessler
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Dmitri I Svergun
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestrasse 85, 22603, Hamburg, Germany
| | - Stephen High
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, The Michael Smith Building, Oxford Road, Manchester, M13 9PT, UK
| | - Rivka L Isaacson
- Department of Chemistry, King's College London, Britannia House, Trinity Street, London, SE1 1DB, UK.
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89
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The VCP-UBXN1 Complex Mediates Triage of Ubiquitylated Cytosolic Proteins Bound to the BAG6 Complex. Mol Cell Biol 2018; 38:MCB.00154-18. [PMID: 29685906 DOI: 10.1128/mcb.00154-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022] Open
Abstract
A balance between protein synthesis and degradation is necessary to maintain cellular homeostasis. Failure to triage aberrant proteins may result in their accumulation and aggregation in the cytosol. The valosin-containing protein (VCP)-BCL2-associated athanogene 6 (BAG6) complex facilitates a wide variety of ubiquitin-mediated quality control events at the endoplasmic reticulum (ER), both prior to ER translocation and during ER-associated degradation (ERAD). However, how ubiquitylated clients associated with BAG6 are recognized by VCP for proteasomal degradation is presently unknown. We have identified UBXN1 as the VCP adaptor in BAG6-dependent processes occurring prior to ER insertion but not during ERAD. The loss of VCP-UBXN1 results in the inappropriate stabilization of ubiquitylated BAG6 clients and their accumulation in insoluble aggregates and sensitizes cells to proteotoxic stress. Our results identify how VCP is specifically targeted to ubiquitylated substrates in the BAG6 triage pathway and suggest that the degradation of ubiquitylated clients by the proteasome is reliant on the association of UBXN1 with ubiquitylated substrates and the catalytic activity of VCP.
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90
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Abstract
Proper localization of membrane proteins is essential for the function of biological membranes and for the establishment of organelle identity within a cell. Molecular machineries that mediate membrane protein biogenesis need to not only achieve a high degree of efficiency and accuracy, but also prevent off-pathway aggregation events that can be detrimental to cells. The posttranslational targeting of tail-anchored proteins (TAs) provides tractable model systems to probe these fundamental issues. Recent advances in understanding TA-targeting pathways reveal sophisticated molecular machineries that drive and regulate these processes. These findings also suggest how an interconnected network of targeting factors, cochaperones, and quality control machineries together ensures robust membrane protein biogenesis.
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Affiliation(s)
- Un Seng Chio
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125; , ,
| | - Hyunju Cho
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125; , ,
| | - Shu-Ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125; , ,
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91
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Molecular mechanism of ER stress-induced pre-emptive quality control involving association of the translocon, Derlin-1, and HRD1. Sci Rep 2018; 8:7317. [PMID: 29743537 PMCID: PMC5943263 DOI: 10.1038/s41598-018-25724-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 04/27/2018] [Indexed: 12/19/2022] Open
Abstract
The maintenance of endoplasmic reticulum (ER) homeostasis is essential for cell function. ER stress-induced pre-emptive quality control (ERpQC) helps alleviate the burden to a stressed ER by limiting further protein loading. We have previously reported the mechanisms of ERpQC, which includes a rerouting step and a degradation step. Under ER stress conditions, Derlin family proteins (Derlins), which are components of ER-associated degradation, reroute specific ER-targeting proteins to the cytosol. Newly synthesized rerouted polypeptides are degraded via the cytosolic chaperone Bag6 and the AAA-ATPase p97 in the ubiquitin-proteasome system. However, the mechanisms by which ER-targeting proteins are rerouted from the ER translocation pathway to the cytosolic degradation pathway and how the E3 ligase ubiquitinates ERpQC substrates remain unclear. Here, we show that ERpQC substrates are captured by the carboxyl-terminus region of Derlin-1 and ubiquitinated by the HRD1 E3 ubiquitin ligase prior to degradation. Moreover, HRD1 forms a large ERpQC-related complex composed of Sec61α and Derlin-1 during ER stress. These findings indicate that the association of the degradation factor HRD1 with the translocon and the rerouting factor Derlin-1 may be necessary for the smooth and effective clearance of ERpQC substrates.
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92
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Stefanovic-Barrett S, Dickson AS, Burr SP, Williamson JC, Lobb IT, van den Boomen DJ, Lehner PJ, Nathan JA. MARCH6 and TRC8 facilitate the quality control of cytosolic and tail-anchored proteins. EMBO Rep 2018; 19:e45603. [PMID: 29519897 PMCID: PMC5934766 DOI: 10.15252/embr.201745603] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 02/14/2018] [Accepted: 02/15/2018] [Indexed: 12/26/2022] Open
Abstract
Misfolded or damaged proteins are typically targeted for destruction by proteasome-mediated degradation, but the mammalian ubiquitin machinery involved is incompletely understood. Here, using forward genetic screens in human cells, we find that the proteasome-mediated degradation of the soluble misfolded reporter, mCherry-CL1, involves two ER-resident E3 ligases, MARCH6 and TRC8. mCherry-CL1 degradation is routed via the ER membrane and dependent on the hydrophobicity of the substrate, with complete stabilisation only observed in double knockout MARCH6/TRC8 cells. To identify a more physiological correlate, we used quantitative mass spectrometry and found that TRC8 and MARCH6 depletion altered the turnover of the tail-anchored protein heme oxygenase-1 (HO-1). These E3 ligases associate with the intramembrane cleaving signal peptide peptidase (SPP) and facilitate the degradation of HO-1 following intramembrane proteolysis. Our results highlight how ER-resident ligases may target the same substrates, but work independently of each other, to optimise the protein quality control of selected soluble and tail-anchored proteins.
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Affiliation(s)
- Sandra Stefanovic-Barrett
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Anna S Dickson
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Stephen P Burr
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - James C Williamson
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Ian T Lobb
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Dick Jh van den Boomen
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - Paul J Lehner
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - James A Nathan
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
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93
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Feng Q, Shao S. In vitro reconstitution of translational arrest pathways. Methods 2018; 137:20-36. [DOI: 10.1016/j.ymeth.2017.12.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 12/18/2017] [Accepted: 12/19/2017] [Indexed: 01/17/2023] Open
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94
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Bragoszewski P, Turek M, Chacinska A. Control of mitochondrial biogenesis and function by the ubiquitin-proteasome system. Open Biol 2018; 7:rsob.170007. [PMID: 28446709 PMCID: PMC5413908 DOI: 10.1098/rsob.170007] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/31/2017] [Indexed: 12/17/2022] Open
Abstract
Mitochondria are pivotal organelles in eukaryotic cells. The complex proteome of mitochondria comprises proteins that are encoded by nuclear and mitochondrial genomes. The biogenesis of mitochondrial proteins requires their transport in an unfolded state with a high risk of misfolding. The mislocalization of mitochondrial proteins is deleterious to the cell. The electron transport chain in mitochondria is a source of reactive oxygen species that damage proteins. Mitochondrial dysfunction is linked to many pathological conditions and, together with the loss of cellular protein homeostasis (proteostasis), are hallmarks of ageing and ageing-related degeneration diseases. The pathogenesis of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, has been associated with mitochondrial and proteostasis failure. Thus, mitochondrial proteins require sophisticated surveillance mechanisms. Although mitochondria form a proteasome-exclusive compartment, multiple lines of evidence indicate a crucial role for the cytosolic ubiquitin-proteasome system (UPS) in the quality control of mitochondrial proteins. The proteasome affects mitochondrial proteins at stages of their biogenesis and maturity. The effects of the UPS go beyond the removal of damaged proteins and include the adjustment of mitochondrial proteome composition, the regulation of organelle dynamics and the protection of cellular homeostasis against mitochondrial failure. In turn, mitochondrial activity and mitochondrial dysfunction adjust the activity of the UPS, with implications at the cellular level.
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Affiliation(s)
- Piotr Bragoszewski
- Laboratory of Mitochondrial Biogenesis, International Institute of Molecular and Cell Biology, Ks. Trojdena 4, 02-109 Warsaw, Poland
| | - Michal Turek
- Laboratory of Mitochondrial Biogenesis, International Institute of Molecular and Cell Biology, Ks. Trojdena 4, 02-109 Warsaw, Poland
| | - Agnieszka Chacinska
- Laboratory of Mitochondrial Biogenesis, International Institute of Molecular and Cell Biology, Ks. Trojdena 4, 02-109 Warsaw, Poland .,Centre of New Technologies, Warsaw University, Banacha 2c, 02-097 Warsaw, Poland
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95
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Yang X, Pan Y, Qiu Z, Du Z, Zhang Y, Fa P, Gorityala S, Ma S, Li S, Chen C, Wang H, Xu Y, Yan C, Ruth K, Ma Z, Zhang J. RNF126 as a Biomarker of a Poor Prognosis in Invasive Breast Cancer and CHEK1 Inhibitor Efficacy in Breast Cancer Cells. Clin Cancer Res 2018; 24:1629-1643. [PMID: 29326282 DOI: 10.1158/1078-0432.ccr-17-2242] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/10/2017] [Accepted: 01/05/2018] [Indexed: 01/20/2023]
Abstract
Purpose: (i) To investigate the expression of the E3 ligase, RNF126, in human invasive breast cancer and its links with breast cancer outcomes; and (ii) to test the hypothesis that RNF126 determines the efficacy of inhibitors targeting the cell-cycle checkpoint kinase, CHEK1.Experimental Design: A retrospective analysis by immunohistochemistry (IHC) compared RNF126 staining in 110 invasive breast cancer and 78 paired adjacent normal tissues with clinicopathologic data. Whether RNF126 controls CHEK1 expression was determined by chromatin immunoprecipitation and a CHEK1 promoter driven luciferase reporter. Staining for these two proteins by IHC using tissue microarrays was also conducted. Cell killing/replication stress induced by CHEK1 inhibition was evaluated in cells, with or without RNF126 knockdown, by MTT/colony formation, replication stress biomarker immunostaining and DNA fiber assays.Results: RNF126 protein expression was elevated in breast cancer tissue samples. RNF126 was associated with a poor clinical outcome after multivariate analysis and was an independent predictor. RNF126 promotes CHEK1 transcript expression. Critically, a strong correlation between RNF126 and CHEK1 proteins was identified in breast cancer tissue and cell lines. The inhibition of CHEK1 induced a greater cell killing and a higher level of replication stress in breast cancer cells expressing RNF126 compared to RNF126 depleted cells.Conclusions: RNF126 protein is highly expressed in invasive breast cancer tissue. The high expression of RNF126 is an independent predictor of a poor prognosis in invasive breast cancer and is considered a potential biomarker of a cancer's responsiveness to CHEK1 inhibitors. CHEK1 inhibition targets breast cancer cells expressing higher levels of RNF126 by enhancing replication stress. Clin Cancer Res; 24(7); 1629-43. ©2018 AACR.
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Affiliation(s)
- Xiaosong Yang
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Department of Breast Surgery, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - You Pan
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Department of Breast Surgery, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Zhaojun Qiu
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Zhanwen Du
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Yao Zhang
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Pengyan Fa
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | | | - Shanhuai Ma
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Shunqiang Li
- Division of Oncology Breast Oncology Section, Washington University Medical School, St. Louis, Missouri
| | - Ceshi Chen
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Kunming, Yunnan, China
| | - Hongbing Wang
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland
| | - Yan Xu
- Department of Chemistry, Cleveland State University, Cleveland, Ohio.,Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Chunhong Yan
- Georgia Cancer Center, Augusta University, Augusta, Georgia
| | - Keri Ruth
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Zhefu Ma
- Department of Breast Surgery, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China. .,Department of Breast Surgery & Plastic Surgery, Cancer Hospital of China Medical University, Shenyang, China
| | - Junran Zhang
- Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, Ohio. .,Department of Radiation Oncology, The Ohio State University, Columbus, Ohio
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96
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Yanagitani K, Juszkiewicz S, Hegde RS. UBE2O is a quality control factor for orphans of multiprotein complexes. Science 2018; 357:472-475. [PMID: 28774922 DOI: 10.1126/science.aan0178] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 06/08/2017] [Indexed: 01/02/2023]
Abstract
Many nascent proteins are assembled into multiprotein complexes of defined stoichiometry. Imbalances in the synthesis of individual subunits result in orphans. How orphans are selectively eliminated to maintain protein homeostasis is poorly understood. Here, we found that the conserved ubiquitin-conjugating enzyme UBE2O directly recognized juxtaposed basic and hydrophobic patches on unassembled proteins to mediate ubiquitination without a separate ubiquitin ligase. In reticulocytes, where UBE2O is highly up-regulated, unassembled α-globin molecules that failed to assemble with β-globin were selectively ubiquitinated by UBE2O. In nonreticulocytes, ribosomal proteins that did not engage nuclear import factors were targets for UBE2O. Thus, UBE2O is a self-contained quality control factor that comprises substrate recognition and ubiquitin transfer activities within a single protein to efficiently target orphans of multiprotein complexes for degradation.
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Affiliation(s)
- Kota Yanagitani
- Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Szymon Juszkiewicz
- Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Ramanujan S Hegde
- Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK.
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97
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Elimination of a signal sequence-uncleaved form of defective HLA protein through BAG6. Sci Rep 2017; 7:14545. [PMID: 29109525 PMCID: PMC5674028 DOI: 10.1038/s41598-017-14975-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 10/16/2017] [Indexed: 12/15/2022] Open
Abstract
A portion of newly synthesized transmembrane domain proteins tend to fail to assemble correctly in the lumen of the endoplasmic reticulum, thus resulting in the production of a signal sequence-uncleaved form of the defective species. Although the efficient degradation of these mistargeted polypeptides is crucial, the molecular mechanism of their elimination pathway has not been adequately characterized. In this study, we focused on one such cryptic portion of a defective transmembrane domain protein, HLA-A, and show that a part of HLA-A is produced as a signal sequence-uncleaved labile species that is immediately targeted to the degradation pathway. We found that both BAG6 and proteasomes are indispensable for elimination of mislocalized HLA-A species. Furthermore, defective HLA-A is subjected to BAG6-dependent solubilization in the cytoplasm. These observations suggest that BAG6 acts as a critical factor for proteasome-mediated degradation of mislocalized HLA-A with a non-cleaved signal sequence at its N-terminus.
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98
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Gonsberg A, Jung S, Ulbrich S, Origi A, Ziska A, Baier M, Koch HG, Zimmermann R, Winklhofer KF, Tatzelt J. The Sec61/SecY complex is inherently deficient in translocating intrinsically disordered proteins. J Biol Chem 2017; 292:21383-21396. [PMID: 29084847 DOI: 10.1074/jbc.m117.788067] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 10/26/2017] [Indexed: 11/06/2022] Open
Abstract
About one-quarter to nearly one-third of the proteins synthesized in the cytosol of eukaryotic cells are integrated into the plasma membrane or are secreted. Translocation of secretory proteins into the lumen of the endoplasmic reticulum or the periplasm of bacteria is mediated by a highly conserved heterotrimeric membrane protein complex denoted Sec61 in eukaryotes and SecYEG in bacteria. To evaluate a possible modulation of the translocation efficiency by secondary structures of the nascent peptide chain, we performed a comparative analysis in bacteria, yeast, and mammalian cells. Strikingly, neither the bacterial SecY nor the eukaryotic Sec61 translocon was able to efficiently transport proteins entirely composed of intrinsically disordered domains (IDDs) or β-strands. However, translocation could be restored by α-helical domains in a position- and organism-dependent manner. In bacteria, we found that the α-helical domains have to precede the IDD or β-strands, whereas in mammalian cells, C-terminally located α-helical domains are sufficient to promote translocation. Our study reveals an evolutionarily conserved deficiency of the Sec61/SecY complex to translocate IDDs and β-strands in the absence of α-helical domains. Moreover, our results may suggest that adaptive pathways co-evolved with the expansion of IDDs in the proteome of eukaryotic cells to increase the transport capacity of the Sec61 translocon.
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Affiliation(s)
- Anika Gonsberg
- From the Departments of Biochemistry of Neurodegenerative Diseases and
| | - Sebastian Jung
- From the Departments of Biochemistry of Neurodegenerative Diseases and
| | - Sarah Ulbrich
- From the Departments of Biochemistry of Neurodegenerative Diseases and
| | - Andrea Origi
- the Institute of Biochemistry and Molecular Biology, Faculty of Medicine, Albert-Ludwigs-University Freiburg, D-79104 Freiburg im Breisgau, Germany
| | - Anke Ziska
- the Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66421 Homburg, Germany, and
| | - Michael Baier
- the Research Group Proteinopathies/Neurodegenerative Diseases, Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, D-13353 Berlin, Germany
| | - Hans-Georg Koch
- the Institute of Biochemistry and Molecular Biology, Faculty of Medicine, Albert-Ludwigs-University Freiburg, D-79104 Freiburg im Breisgau, Germany
| | - Richard Zimmermann
- the Department of Medical Biochemistry and Molecular Biology, Saarland University, D-66421 Homburg, Germany, and
| | - Konstanze F Winklhofer
- Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, D-44801 Bochum, Germany
| | - Jörg Tatzelt
- From the Departments of Biochemistry of Neurodegenerative Diseases and
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99
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Shao S, Rodrigo-Brenni MC, Kivlen MH, Hegde RS. Mechanistic basis for a molecular triage reaction. Science 2017; 355:298-302. [PMID: 28104892 DOI: 10.1126/science.aah6130] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 12/22/2016] [Indexed: 01/24/2023]
Abstract
Newly synthesized proteins are triaged between biosynthesis and degradation to maintain cellular homeostasis, but the decision-making mechanisms are unclear. We reconstituted the core reactions for membrane targeting and ubiquitination of nascent tail-anchored membrane proteins to understand how their fate is determined. The central six-component triage system is divided into an uncommitted client-SGTA complex, a self-sufficient targeting module, and an embedded but self-sufficient quality control module. Client-SGTA engagement of the targeting module induces rapid, private, and committed client transfer to TRC40 for successful biosynthesis. Commitment to ubiquitination is dictated primarily by comparatively slower client dissociation from SGTA and nonprivate capture by the BAG6 subunit of the quality control module. Our results provide a paradigm for how priority and time are encoded within a multichaperone triage system.
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Affiliation(s)
- Sichen Shao
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Monica C Rodrigo-Brenni
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Maryann H Kivlen
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Ramanujan S Hegde
- Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
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100
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Structural basis for regulation of the nucleo-cytoplasmic distribution of Bag6 by TRC35. Proc Natl Acad Sci U S A 2017; 114:11679-11684. [PMID: 29042515 DOI: 10.1073/pnas.1702940114] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The metazoan protein BCL2-associated athanogene cochaperone 6 (Bag6) forms a hetero-trimeric complex with ubiquitin-like 4A and transmembrane domain recognition complex 35 (TRC35). This Bag6 complex is involved in tail-anchored protein targeting and various protein quality-control pathways in the cytosol as well as regulating transcription and histone methylation in the nucleus. Here we present a crystal structure of Bag6 and its cytoplasmic retention factor TRC35, revealing that TRC35 is remarkably conserved throughout the opisthokont lineage except at the C-terminal Bag6-binding groove, which evolved to accommodate Bag6, a unique metazoan factor. While TRC35 and its fungal homolog, guided entry of tail-anchored protein 4 (Get4), utilize a conserved hydrophobic patch to bind their respective partners, Bag6 wraps around TRC35 on the opposite face relative to the Get4-5 interface. We further demonstrate that TRC35 binding is critical not only for occluding the Bag6 nuclear localization sequence from karyopherin α to retain Bag6 in the cytosol but also for preventing TRC35 from succumbing to RNF126-mediated ubiquitylation and degradation. The results provide a mechanism for regulation of Bag6 nuclear localization and the functional integrity of the Bag6 complex in the cytosol.
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