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Meng X, Wu Q, Cao C, Yang W, Chu S, Guo H, Qi S, Bai J. A novel peptide encoded by circSRCAP confers resistance to enzalutamide by inhibiting the ubiquitin-dependent degradation of AR-V7 in castration-resistant prostate cancer. J Transl Med 2025; 23:108. [PMID: 39844192 PMCID: PMC11755828 DOI: 10.1186/s12967-025-06115-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2024] [Accepted: 01/08/2025] [Indexed: 01/30/2025] Open
Abstract
BACKGROUND The sustained activation of androgen receptor splice variant-7 (AR-V7) is a key factor in the resistance of castration-resistant prostate cancer (CRPC) to second-generation anti-androgens such as enzalutamide (ENZ). The AR/AR-V7 protein is regulated by the E3 ubiquitin ligase STUB1 and a complex involving HSP70, but the precise mechanism remains unclear. METHODS High-throughput RNA sequencing was used to identify differentially expressed circular RNAs (circRNAs) in ENZ-resistant and control CRPC cells. The coding potential of circSRCAP was confirmed by polysome profiling and LC-MS. The function of circSRCAP was validated in vitro and in vivo using gain- and loss-of-function assays. Mechanistic insights were obtained through immunoprecipitation analyses. RESULTS A novel ENZ-resistant circRNA, circSRCAP, was identified and shown to be upregulated in ENZ-resistant C4-2B (ENZR-C4-2B) cells, correlating with increased AR-V7 protein levels. circSRCAP is generated via splicing by eIF4A3, forming a loop structure and is exported from the nucleus by the RNA helicase DDX39A. Mechanistically, circSRCAP encodes a 75-amino acid peptide (circSRCAP-75aa) that inhibits the ubiquitination of AR/AR-V7's co-chaperone protein HSP70 by disrupting the interaction with the E3 ligase STUB1. This process results in the upregulation of AR-V7 expression and promotes ENZ resistance in CRPC cells. Xenograft tumor models further confirmed the role of circSRCAP in CRPC progression and its potential as a therapeutic target for ENZ-resistant CRPC. CONCLUSIONS circSRCAP provides an epigenetic mechanism influencing AR-V7 stability and offers a promising therapeutic target for treating ENZ-resistant CRPC.
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MESH Headings
- Male
- Prostatic Neoplasms, Castration-Resistant/genetics
- Prostatic Neoplasms, Castration-Resistant/drug therapy
- Prostatic Neoplasms, Castration-Resistant/pathology
- Humans
- Phenylthiohydantoin/pharmacology
- Phenylthiohydantoin/analogs & derivatives
- Phenylthiohydantoin/therapeutic use
- RNA, Circular/metabolism
- RNA, Circular/genetics
- Benzamides
- Drug Resistance, Neoplasm/genetics
- Drug Resistance, Neoplasm/drug effects
- Receptors, Androgen/metabolism
- Receptors, Androgen/genetics
- Proteolysis/drug effects
- Cell Line, Tumor
- Animals
- Nitriles
- Ubiquitin/metabolism
- Peptides/chemistry
- Peptides/pharmacology
- Peptides/metabolism
- Peptides/genetics
- Ubiquitin-Protein Ligases/metabolism
- Mice, Nude
- Protein Isoforms/metabolism
- Mice
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Affiliation(s)
- Xiannan Meng
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Qingxuan Wu
- School of Medical Technology, Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Chengsong Cao
- Department of Oncology, Xuzhou Central Hospital, Xuzhou, Jiangsu, China
- Department of Oncology, Xuzhou Institute of Medical Science, Xuzhou, Jiangsu, China
| | - Wendong Yang
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Sufang Chu
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China
| | - Hongjun Guo
- Department of General Surgery, Xi'an Central Hospital, Xi'an, 710004, Shaanxi, China.
| | - Suhua Qi
- School of Medical Technology, Xuzhou Key Laboratory of Laboratory Diagnostics, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
| | - Jin Bai
- Cancer Institute, Xuzhou Medical University, 209 Tongshan Road, Xuzhou, 221004, Jiangsu, China.
- Center of Clinical Oncology, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.
- Jiangsu Center for the Collaboration and Innovation of Cancer Biotherapy, Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu, China.
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2
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Hua Z. Deciphering the protein ubiquitylation system in plants. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:6487-6504. [PMID: 37688404 DOI: 10.1093/jxb/erad354] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 09/07/2023] [Indexed: 09/10/2023]
Abstract
Protein ubiquitylation is a post-translational modification (PTM) process that covalently modifies a protein substrate with either mono-ubiquitin moieties or poly-ubiquitin chains often at the lysine residues. In Arabidopsis, bioinformatic predictions have suggested that over 5% of its proteome constitutes the protein ubiquitylation system. Despite advancements in functional genomic studies in plants, only a small fraction of this bioinformatically predicted system has been functionally characterized. To expand our understanding about the regulatory function of protein ubiquitylation to that rivalling several other major systems, such as transcription regulation and epigenetics, I describe the status, issues, and new approaches of protein ubiquitylation studies in plant biology. I summarize the methods utilized in defining the ubiquitylation machinery by bioinformatics, identifying ubiquitylation substrates by proteomics, and characterizing the ubiquitin E3 ligase-substrate pathways by functional genomics. Based on the functional and evolutionary analyses of the F-box gene superfamily, I propose a deleterious duplication model for the large expansion of this family in plant genomes. Given this model, I present new perspectives of future functional genomic studies on the plant ubiquitylation system to focus on core and active groups of ubiquitin E3 ligase genes.
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Affiliation(s)
- Zhihua Hua
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
- Interdisciplinary Program in Molecular and Cellular Biology, Ohio University, Athens, OH 45701, USA
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3
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Sinha N, Zahra T, Gahane AY, Rout B, Bhattacharya A, Basu S, Chakrabarti A, Thakur AK. Protein reservoirs of seeds are amyloid composites employed differentially for germination and seedling emergence. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:329-346. [PMID: 37675599 DOI: 10.1111/tpj.16429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/15/2023] [Accepted: 08/07/2023] [Indexed: 09/08/2023]
Abstract
Seed protein localization in seed storage protein bodies (SSPB) and their significance in germination are well recognized. SSPB are spherical and contain an assembly of water-soluble and salt-soluble proteins. Although the native structures of some SSPB proteins are explored, their structural arrangement to the functional correlation in SSPB remains unknown. SSPB are morphologically analogous to electron-dense amyloid-containing structures reported in other organisms. Here, we show that wheat, mungbean, barley, and chickpea SSPB exhibit a speckled pattern of amyloids interspersed in an amyloid-like matrix along with native structures, suggesting the composite nature of SSPB. This is confirmed by multispectral imaging methods, electron microscopy, infrared, and X-ray diffraction analysis, using in situ tissue sections, ex vivo protoplasts, and in vitro SSPB. Laser capture microdissection coupled with peptide fingerprinting has shown that globulin 1 and 3 in wheat, and 8S globulin and conglycinin in mungbean are the major amyloidogenic proteins. The amyloid composites undergo a sustained degradation during germination and seedling growth, facilitated by an intricate interplay of plant hormones and proteases. These results would lay down the foundation for understanding the amyloid composite structure during SSPB biogenesis and its evolution across the plant kingdom and have implications in both basic and applied plant biology.
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Affiliation(s)
- Nabodita Sinha
- Department of Biological Sciences and Bioengineering, The Mehta Family Centre For Engineering in Medicine, Indian Institute of Technology, Kanpur, Uttar Pradesh, 208016, India
| | - Talat Zahra
- Department of Biological Sciences and Bioengineering, The Mehta Family Centre For Engineering in Medicine, Indian Institute of Technology, Kanpur, Uttar Pradesh, 208016, India
| | - Avinash Yashwant Gahane
- Department of Biological Sciences and Bioengineering, The Mehta Family Centre For Engineering in Medicine, Indian Institute of Technology, Kanpur, Uttar Pradesh, 208016, India
| | - Bandita Rout
- Department of Biological Sciences and Bioengineering, The Mehta Family Centre For Engineering in Medicine, Indian Institute of Technology, Kanpur, Uttar Pradesh, 208016, India
| | | | | | | | - Ashwani Kumar Thakur
- Department of Biological Sciences and Bioengineering, The Mehta Family Centre For Engineering in Medicine, Indian Institute of Technology, Kanpur, Uttar Pradesh, 208016, India
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4
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Yu P, Hua Z. To Kill or to Be Killed: How Does the Battle between the UPS and Autophagy Maintain the Intracellular Homeostasis in Eukaryotes? Int J Mol Sci 2023; 24:ijms24032221. [PMID: 36768543 PMCID: PMC9917186 DOI: 10.3390/ijms24032221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/18/2023] [Accepted: 01/19/2023] [Indexed: 01/27/2023] Open
Abstract
The ubiquitin-26S proteasome system and autophagy are two major protein degradation machineries encoded in all eukaryotic organisms. While the UPS is responsible for the turnover of short-lived and/or soluble misfolded proteins under normal growth conditions, the autophagy-lysosomal/vacuolar protein degradation machinery is activated under stress conditions to remove long-lived proteins in the forms of aggregates, either soluble or insoluble, in the cytoplasm and damaged organelles. Recent discoveries suggested an integrative function of these two seemly independent systems for maintaining the proteome homeostasis. One such integration is represented by their reciprocal degradation, in which the small 76-amino acid peptide, ubiquitin, plays an important role as the central signaling hub. In this review, we summarized the current knowledge about the activity control of proteasome and autophagosome at their structural organization, biophysical states, and turnover levels from yeast and mammals to plants. Through comprehensive literature studies, we presented puzzling questions that are awaiting to be solved and proposed exciting new research directions that may shed light on the molecular mechanisms underlying the biological function of protein degradation.
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Affiliation(s)
- Peifeng Yu
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
- Interdisciplinary Program in Molecular and Cellular Biology, Ohio University, Athens, OH 45701, USA
| | - Zhihua Hua
- Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA
- Interdisciplinary Program in Molecular and Cellular Biology, Ohio University, Athens, OH 45701, USA
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5
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Jawed A, Ho CT, Grousl T, Shrivastava A, Ruppert T, Bukau B, Mogk A. Balanced activities of Hsp70 and the ubiquitin proteasome system underlie cellular protein homeostasis. Front Mol Biosci 2023; 9:1106477. [PMID: 36660429 PMCID: PMC9845930 DOI: 10.3389/fmolb.2022.1106477] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/15/2022] [Indexed: 01/05/2023] Open
Abstract
To counteract proteotoxic stress and cellular aging, protein quality control (PQC) systems rely on the refolding, degradation and sequestration of misfolded proteins. In Saccharomyces cerevisiae the Hsp70 chaperone system plays a central role in protein refolding, while degradation is predominantly executed by the ubiquitin proteasome system (UPS). The sequestrases Hsp42 and Btn2 deposit misfolded proteins in cytosolic and nuclear inclusions, thereby restricting the accessibility of misfolded proteins to Hsp70 and preventing the exhaustion of limited Hsp70 resources. Therefore, in yeast, sequestrase mutants show negative genetic interactions with double mutants lacking the Hsp70 co-chaperone Fes1 and the Hsp104 disaggregase (fes1Δ hsp104Δ, ΔΔ) and suffering from low Hsp70 capacity. Growth of ΔΔbtn2Δ mutants is highly temperature-sensitive and results in proteostasis breakdown at non-permissive temperatures. Here, we probed for the role of the ubiquitin proteasome system in maintaining protein homeostasis in ΔΔbtn2Δ cells, which are affected in two major protein quality control branches. We show that ΔΔbtn2Δ cells induce expression of diverse stress-related pathways including the ubiquitin proteasome system to counteract the proteostasis defects. Ubiquitin proteasome system dependent degradation of the stringent Hsp70 substrate firefly Luciferase in the mutant cells mirrors such compensatory activities of the protein quality control system. Surprisingly however, the enhanced ubiquitin proteasome system activity does not improve but aggravates the growth defects of ΔΔbtn2Δ cells. Reducing ubiquitin proteasome system activity in the mutant by lowering the levels of functional 26S proteasomes improved growth, increased refolding yield of the Luciferase reporter and attenuated global stress responses. Our findings indicate that an imbalance between Hsp70-dependent refolding, sequestration and ubiquitin proteasome system-mediated degradation activities strongly affects protein homeostasis of Hsp70 capacity mutants and contributes to their severe growth phenotypes.
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Affiliation(s)
- Areeb Jawed
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Chi-Ting Ho
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Tomas Grousl
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Aseem Shrivastava
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Thomas Ruppert
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany,*Correspondence: Axel Mogk, ; Bernd Bukau,
| | - Axel Mogk
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany,*Correspondence: Axel Mogk, ; Bernd Bukau,
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6
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Inactive Proteasomes Routed to Autophagic Turnover Are Confined within the Soluble Fraction of the Cell. Biomolecules 2022; 13:biom13010077. [PMID: 36671462 PMCID: PMC9855985 DOI: 10.3390/biom13010077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 01/01/2023] Open
Abstract
Previous studies demonstrated that dysfunctional yeast proteasomes accumulate in the insoluble protein deposit (IPOD), described as the final deposition site for amyloidogenic insoluble proteins and that this compartment also mediates proteasome ubiquitination, a prerequisite for their targeted autophagy (proteaphagy). Here, we examined the solubility state of proteasomes subjected to autophagy as a result of their inactivation, or under nutrient starvation. In both cases, only soluble proteasomes could serve as a substrate to autophagy, suggesting a modified model whereby substrates for proteaphagy are dysfunctional proteasomes in their near-native soluble state, and not as previously believed, those sequestered at the IPOD. Furthermore, the insoluble fraction accumulating in the IPOD represents an alternative pathway, enabling the removal of inactive proteasomes that escaped proteaphagy when the system became saturated. Altogether, we suggest that the relocalization of proteasomes to soluble aggregates represents a general stage of proteasome recycling through autophagy.
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7
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Marshall RS, Vierstra RD. A trio of ubiquitin ligases sequentially drives ubiquitylation and autophagic degradation of dysfunctional yeast proteasomes. Cell Rep 2022; 38:110535. [PMID: 35294869 DOI: 10.1016/j.celrep.2022.110535] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 12/08/2021] [Accepted: 02/25/2022] [Indexed: 12/22/2022] Open
Abstract
As central effectors of ubiquitin (Ub)-mediated proteolysis, proteasomes are regulated at multiple levels, including degradation of unwanted or dysfunctional particles via autophagy (termed proteaphagy). In yeast, inactive proteasomes are exported from the nucleus, sequestered into cytoplasmic aggresomes via the Hsp42 chaperone, extensively ubiquitylated, and then tethered to the expanding phagophore by the autophagy receptor Cue5. Here, we demonstrate the need for ubiquitylation driven by the trio of Ub ligases (E3s), San1, Rsp5, and Hul5, which together with their corresponding E2s work sequentially to promote nuclear export and Cue5 recognition. Whereas San1 functions prior to nuclear export, Rsp5 and Hul5 likely decorate aggresome-localized proteasomes in concert. Ultimately, topologically complex Ub chain(s) containing both K48 and K63 Ub-Ub linkages are assembled, mainly on the regulatory particle, to generate autophagy-competent substrates. Because San1, Rsp5, Hul5, Hsp42, and Cue5 also participate in general proteostasis, proteaphagy likely engages a fundamental mechanism for eliminating inactive/misfolded proteins.
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Affiliation(s)
- Richard S Marshall
- Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63130, USA.
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63130, USA.
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8
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Singh Gautam AK, Yu H, Yellman C, Elcock AH, Matouschek A. Design principles that protect the proteasome from self-destruction. Protein Sci 2022; 31:556-567. [PMID: 34878680 PMCID: PMC8862440 DOI: 10.1002/pro.4251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 12/07/2021] [Accepted: 12/07/2021] [Indexed: 11/07/2022]
Abstract
The proteasome is a powerful intracellular protease that can degrade effectively any protein, self or foreign, for regulation, quality control, or immune response. Proteins are targeted for degradation by localizing them to the proteasome, typically by ubiquitin tags. At the same time, the proteasome is built from ~33 subunits, and their assembly into the complex and activity are tuned by post-translational modifications on long disordered regions on the subunits. Molecular modeling and biochemical experiments show that some of the disordered regions of proteasomal subunits can access the substrate recognition sites. All disordered regions tested, independent of location, are constructed from amino acid sequences that escape recognition. Replacing a disordered region with a sequence that is recognized by the proteasome leads to self-degradation and, in the case of an essential subunit, cell death.
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Affiliation(s)
| | - Houqing Yu
- Department of Molecular BiosciencesThe University of Texas at AustinAustinTexasUSA
| | - Christopher Yellman
- Department of Molecular BiosciencesThe University of Texas at AustinAustinTexasUSA
| | - Adrian H. Elcock
- Department of Biochemistry, Carver College of MedicineUniversity of IowaIowa CityIowaUSA
| | - Andreas Matouschek
- Department of Molecular BiosciencesThe University of Texas at AustinAustinTexasUSA
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9
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Hommen F, Bilican S, Vilchez D. Protein clearance strategies for disease intervention. J Neural Transm (Vienna) 2021; 129:141-172. [PMID: 34689261 PMCID: PMC8541819 DOI: 10.1007/s00702-021-02431-y] [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: 06/18/2021] [Accepted: 10/10/2021] [Indexed: 02/06/2023]
Abstract
Protein homeostasis, or proteostasis, is essential for cell function and viability. Unwanted, damaged, misfolded and aggregated proteins are degraded by the ubiquitin–proteasome system (UPS) and the autophagy-lysosome pathway. Growing evidence indicates that alterations in these major proteolytic mechanisms lead to a demise in proteostasis, contributing to the onset and development of distinct diseases. Indeed, dysregulation of the UPS or autophagy is linked to several neurodegenerative, infectious and inflammatory disorders as well as cancer. Thus, modulation of protein clearance pathways is a promising approach for therapeutics. In this review, we discuss recent findings and open questions on how targeting proteolytic mechanisms could be applied for disease intervention.
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Affiliation(s)
- Franziska Hommen
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - Saygın Bilican
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany
| | - David Vilchez
- Cologne Excellence Cluster for Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Joseph Stelzmann Strasse 26, 50931, Cologne, Germany. .,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany. .,Faculty of Medicine, University Hospital Cologne, Cologne, Germany.
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10
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Popova B, Galka D, Häffner N, Wang D, Schmitt K, Valerius O, Knop M, Braus GH. α-Synuclein Decreases the Abundance of Proteasome Subunits and Alters Ubiquitin Conjugates in Yeast. Cells 2021; 10:cells10092229. [PMID: 34571878 PMCID: PMC8468666 DOI: 10.3390/cells10092229] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 01/18/2023] Open
Abstract
Parkinson’s disease (PD) is the most prevalent movement disorder characterized with loss of dopaminergic neurons in the brain. One of the pathological hallmarks of the disease is accumulation of aggregated α-synuclein (αSyn) in cytoplasmic Lewy body inclusions that indicates significant dysfunction of protein homeostasis in PD. Accumulation is accompanied with highly elevated S129 phosphorylation, suggesting that this posttranslational modification is linked to pathogenicity and altered αSyn inclusion dynamics. To address the role of S129 phosphorylation on protein dynamics further we investigated the wild type and S129A variants using yeast and a tandem fluorescent timer protein reporter approach to monitor protein turnover and stability. Overexpression of both variants leads to inhibited yeast growth. Soluble S129A is more stable and additional Y133F substitution permits αSyn degradation in a phosphorylation-independent manner. Quantitative cellular proteomics revealed significant αSyn-dependent disturbances of the cellular protein homeostasis, which are increased upon S129 phosphorylation. Disturbances are characterized by decreased abundance of the ubiquitin-dependent protein degradation machinery. Biotin proximity labelling revealed that αSyn interacts with the Rpt2 base subunit. Proteasome subunit depletion by reducing the expression of the corresponding genes enhances αSyn toxicity. Our studies demonstrate that turnover of αSyn and depletion of the proteasome pool correlate in a complex relationship between altered proteasome composition and increased αSyn toxicity.
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Affiliation(s)
- Blagovesta Popova
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
- Correspondence: (B.P.); (G.H.B.)
| | - Dajana Galka
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Nicola Häffner
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Dan Wang
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, 69120 Heidelberg, Germany;
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
- Correspondence: (B.P.); (G.H.B.)
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11
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p62-containing, proteolytically active nuclear condensates, increase the efficiency of the ubiquitin-proteasome system. Proc Natl Acad Sci U S A 2021; 118:2107321118. [PMID: 34385323 DOI: 10.1073/pnas.2107321118] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Degradation of a protein by the ubiquitin-proteasome system (UPS) is a multistep process catalyzed by sequential reactions. Initially, ubiquitin is conjugated to the substrate in a process mediated by concerted activity of three enzymes; the last of them-a ubiquitin ligase (E3)-belongs to a family of several hundred members, each recognizing a few specific substrates. This is followed by repeated addition of ubiquitin moieties to the previously conjugated one to generate a ubiquitin chain that serves as a recognition element for the proteasome, which then degrades the substrate. Ubiquitin is recycled via the activity of deubiquitinating enzymes (DUBs). It stands to reason that efficiency of such a complex process would depend on colocalization of the different components in an assembly that allows the reactions to be carried out sequentially and processively. Here we describe nuclear condensates that are dynamic in their composition. They contain p62 as an essential component. These assemblies are generated by liquid-liquid phase separation (LLPS) and also contain ubiquitinated targets, 26S proteasome, the three conjugating enzymes, and DUBs. Under basal conditions, they serve as efficient centers for proteolysis of nuclear proteins (e.g., c-Myc) and unassembled subunits of the proteasome, suggesting they are involved in cellular protein quality control. Supporting this notion is the finding that such foci are also involved in degradation of misfolded proteins induced by heat and oxidative stresses, following recruitment of heat shock proteins and their associated ubiquitin ligase CHIP.
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12
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Reinle K, Mogk A, Bukau B. The Diverse Functions of Small Heat Shock Proteins in the Proteostasis Network. J Mol Biol 2021; 434:167157. [PMID: 34271010 DOI: 10.1016/j.jmb.2021.167157] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 01/21/2023]
Abstract
The protein quality control (PQC) system maintains protein homeostasis by counteracting the accumulation of misfolded protein conformers. Substrate degradation and refolding activities executed by ATP-dependent proteases and chaperones constitute major strategies of the proteostasis network. Small heat shock proteins represent ATP-independent chaperones that bind to misfolded proteins, preventing their uncontrolled aggregation. sHsps share the conserved α-crystallin domain (ACD) and gain functional specificity through variable and largely disordered N- and C-terminal extensions (NTE, CTE). They form large, polydisperse oligomers through multiple, weak interactions between NTE/CTEs and ACD dimers. Sequence variations of sHsps and the large variability of sHsp oligomers enable sHsps to fulfill diverse tasks in the PQC network. sHsp oligomers represent inactive yet dynamic resting states that are rapidly deoligomerized and activated upon stress conditions, releasing substrate binding sites in NTEs and ACDs Bound substrates are usually isolated in large sHsp/substrate complexes. This sequestration activity of sHsps represents a third strategy of the proteostasis network. Substrate sequestration reduces the burden for other PQC components during immediate and persistent stress conditions. Sequestered substrates can be released and directed towards refolding pathways by ATP-dependent Hsp70/Hsp100 chaperones or sorted for degradation by autophagic pathways. sHsps can also maintain the dynamic state of phase-separated stress granules (SGs), which store mRNA and translation factors, by reducing the accumulation of misfolded proteins inside SGs and preventing unfolding of SG components. This ensures SG disassembly and regain of translational capacity during recovery periods.
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Affiliation(s)
- Kevin Reinle
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Axel Mogk
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
| | - Bernd Bukau
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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13
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Kong KYE, Coelho JPL, Feige MJ, Khmelinskii A. Quality control of mislocalized and orphan proteins. Exp Cell Res 2021; 403:112617. [PMID: 33930402 DOI: 10.1016/j.yexcr.2021.112617] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 04/10/2021] [Accepted: 04/18/2021] [Indexed: 12/16/2022]
Abstract
A healthy and functional proteome is essential to cell physiology. However, this is constantly being challenged as most steps of protein metabolism are error-prone and changes in the physico-chemical environment can affect protein structure and function, thereby disrupting proteome homeostasis. Among a variety of potential mistakes, proteins can be targeted to incorrect compartments or subunits of protein complexes may fail to assemble properly with their partners, resulting in the formation of mislocalized and orphan proteins, respectively. Quality control systems are in place to handle these aberrant proteins, and to minimize their detrimental impact on cellular functions. Here, we discuss recent findings on quality control mechanisms handling mislocalized and orphan proteins. We highlight common principles involved in their recognition and summarize how accumulation of these aberrant molecules is associated with aging and disease.
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Affiliation(s)
| | - João P L Coelho
- Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Garching, Germany
| | - Matthias J Feige
- Department of Chemistry and Institute for Advanced Study, Technical University of Munich, Garching, Germany
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14
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Klickstein JA, Mukkavalli S, Raman M. AggreCount: an unbiased image analysis tool for identifying and quantifying cellular aggregates in a spatially defined manner. J Biol Chem 2021; 295:17672-17683. [PMID: 33454006 PMCID: PMC7762942 DOI: 10.1074/jbc.ra120.015398] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 10/13/2020] [Indexed: 01/17/2023] Open
Abstract
Protein quality control is maintained by a number of integrated cellular pathways that monitor the folding and functionality of the cellular proteome. Defects in these pathways lead to the accumulation of misfolded or faulty proteins that may become insoluble and aggregate over time. Protein aggregates significantly contribute to the development of a number of human diseases such as amyotrophic lateral sclerosis, Huntington's disease, and Alzheimer's disease. In vitro, imaging-based, cellular studies have defined key biomolecular components that recognize and clear aggregates; however, no unifying method is available to quantify cellular aggregates, limiting our ability to reproducibly and accurately quantify these structures. Here we describe an ImageJ macro called AggreCount to identify and measure protein aggregates in cells. AggreCount is designed to be intuitive, easy to use, and customizable for different types of aggregates observed in cells. Minimal experience in coding is required to utilize the script. Based on a user-defined image, AggreCount will report a number of metrics: (i) total number of cellular aggregates, (ii) percentage of cells with aggregates, (iii) aggregates per cell, (iv) area of aggregates, and (v) localization of aggregates (cytosol, perinuclear, or nuclear). A data table of aggregate information on a per cell basis, as well as a summary table, is provided for further data analysis. We demonstrate the versatility of AggreCount by analyzing a number of different cellular aggregates including aggresomes, stress granules, and inclusion bodies caused by huntingtin polyglutamine expansion.
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Affiliation(s)
- Jacob Aaron Klickstein
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Sirisha Mukkavalli
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Malavika Raman
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, Massachusetts, USA.
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15
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Abstract
The 26S proteasome is the most complex ATP-dependent protease machinery, of ~2.5 MDa mass, ubiquitously found in all eukaryotes. It selectively degrades ubiquitin-conjugated proteins and plays fundamentally indispensable roles in regulating almost all major aspects of cellular activities. To serve as the sole terminal "processor" for myriad ubiquitylation pathways, the proteasome evolved exceptional adaptability in dynamically organizing a large network of proteins, including ubiquitin receptors, shuttle factors, deubiquitinases, AAA-ATPase unfoldases, and ubiquitin ligases, to enable substrate selectivity and processing efficiency and to achieve regulation precision of a vast diversity of substrates. The inner working of the 26S proteasome is among the most sophisticated, enigmatic mechanisms of enzyme machinery in eukaryotic cells. Recent breakthroughs in three-dimensional atomic-level visualization of the 26S proteasome dynamics during polyubiquitylated substrate degradation elucidated an extensively detailed picture of its functional mechanisms, owing to progressive methodological advances associated with cryogenic electron microscopy (cryo-EM). Multiple sites of ubiquitin binding in the proteasome revealed a canonical mode of ubiquitin-dependent substrate engagement. The proteasome conformation in the act of substrate deubiquitylation provided insights into how the deubiquitylating activity of RPN11 is enhanced in the holoenzyme and is coupled to substrate translocation. Intriguingly, three principal modes of coordinated ATP hydrolysis in the heterohexameric AAA-ATPase motor were discovered to regulate intermediate functional steps of the proteasome, including ubiquitin-substrate engagement, deubiquitylation, initiation of substrate translocation and processive substrate degradation. The atomic dissection of the innermost working of the 26S proteasome opens up a new era in our understanding of the ubiquitin-proteasome system and has far-reaching implications in health and disease.
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Affiliation(s)
- Youdong Mao
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, 02215, Massachusetts, USA. .,School of Physics, Center for Quantitative Biology, Peking University, Beijing, 100871, China.
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16
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Devi S, Kim JJ, Singh AP, Kumar S, Dubey AK, Singh SK, Singh RS, Kumar V. Proteotoxicity: A Fatal Consequence of Environmental Pollutants-Induced Impairments in Protein Clearance Machinery. J Pers Med 2021; 11:69. [PMID: 33503824 PMCID: PMC7912547 DOI: 10.3390/jpm11020069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 02/08/2023] Open
Abstract
A tightly regulated protein quality control (PQC) system maintains a healthy balance between correctly folded and misfolded protein species. This PQC system work with the help of a complex network comprised of molecular chaperones and proteostasis. Any intruder, especially environmental pollutants, disrupt the PQC network and lead to PQCs disruption, thus generating damaged and infectious protein. These misfolded/unfolded proteins are linked to several diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, and cataracts. Numerous studies on proteins misfolding and disruption of PQCs by environmental pollutants highlight the necessity of detailed knowledge. This review represents the PQCs network and environmental pollutants' impact on the PQC network, especially through the protein clearance system.
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Affiliation(s)
- Shweta Devi
- Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, Lucknow 226001, India;
| | - Jong-Joo Kim
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Korea;
| | - Anand Prakash Singh
- Division of Cardiovascular Disease, The University of Alabama at Birmingham (UAB), 1720 2nd Ave South, Birmingham, AL 35294-1913, USA;
| | - Surendra Kumar
- Cytogenetics Lab, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India;
| | | | | | - Ravi Shankar Singh
- Department of Biochemistry, Microbiology & Immunology, University of Saskatchewan, Room 4D40, Health Sciences Building, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada
| | - Vijay Kumar
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Korea;
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17
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Cheng CL, Wong MK, Li Y, Hochstrasser M. Conserved proline residues in the coiled coil-OB domain linkers of Rpt proteins facilitate eukaryotic proteasome base assembly. J Biol Chem 2021; 296:100660. [PMID: 33862083 PMCID: PMC8134078 DOI: 10.1016/j.jbc.2021.100660] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 04/02/2021] [Accepted: 04/12/2021] [Indexed: 12/05/2022] Open
Abstract
The proteasome is a large protease complex that degrades many different cellular proteins. In eukaryotes, the 26S proteasome contains six different subunits of the ATPases associated with diverse cellular activities family, Rpt1-Rpt6, which form a hexameric ring as part of the base subcomplex that drives unfolding and translocation of substrates into the proteasome core. Archaeal proteasomes contain only a single Rpt-like ATPases associated with diverse cellular activities ATPase, the proteasome-activating nucleotidase, which forms a trimer of dimers. A key proteasome-activating nucleotidase proline residue (P91) forms cis- and trans-peptide bonds in successive subunits around the ring, allowing efficient dimerization through upstream coiled coils. However, the importance of the equivalent Rpt prolines for eukaryotic proteasome assembly was unknown. Here we showed that the equivalent proline is highly conserved in Rpt2, Rpt3, and Rpt5, and loosely conserved in Rpt1, in deeply divergent eukaryotes. Although in no case was a single Pro-to-Ala substitution in budding yeast strongly deleterious to growth, the rpt5-P76A mutation decreased levels of the protein and induced a mild proteasome assembly defect. Moreover, the rpt2-P103A, rpt3-P93A, and rpt5-P76A mutations all caused synthetic defects when combined with deletions of specific proteasome base assembly chaperones. The rpt2-P103A rpt5-P76A double mutant had uniquely strong growth defects attributable to defects in proteasome base formation. Several Rpt subunits in this mutant formed aggregates that were cleared, at least in part, by Hsp42 chaperone-mediated protein quality control. We propose that the conserved Rpt linker prolines promote efficient 26S proteasome base assembly by facilitating specific ATPase heterodimerization.
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Affiliation(s)
- Chin Leng Cheng
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Michael K Wong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Yanjie Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Mark Hochstrasser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA.
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18
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Peck Justice SA, Barron MP, Qi GD, Wijeratne HRS, Victorino JF, Simpson ER, Vilseck JZ, Wijeratne AB, Mosley AL. Mutant thermal proteome profiling for characterization of missense protein variants and their associated phenotypes within the proteome. J Biol Chem 2020; 295:16219-16238. [PMID: 32878984 PMCID: PMC7705321 DOI: 10.1074/jbc.ra120.014576] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/17/2020] [Indexed: 12/20/2022] Open
Abstract
Temperature-sensitive (TS) missense mutants have been foundational for characterization of essential gene function. However, an unbiased approach for analysis of biochemical and biophysical changes in TS missense mutants within the context of their functional proteomes is lacking. We applied MS-based thermal proteome profiling (TPP) to investigate the proteome-wide effects of missense mutations in an application that we refer to as mutant thermal proteome profiling (mTPP). This study characterized global impacts of temperature sensitivity-inducing missense mutations in two different subunits of the 26S proteasome. The majority of alterations identified by RNA-Seq and global proteomics were similar between the mutants, which could suggest that a similar functional disruption is occurring in both missense variants. Results from mTPP, however, provide unique insights into the mechanisms that contribute to the TS phenotype in each mutant, revealing distinct changes that were not obtained using only steady-state transcriptome and proteome analyses. Computationally, multisite λ-dynamics simulations add clear support for mTPP experimental findings. This work shows that mTPP is a precise approach to measure changes in missense mutant-containing proteomes without the requirement for large amounts of starting material, specific antibodies against proteins of interest, and/or genetic manipulation of the biological system. Although experiments were performed under permissive conditions, mTPP provided insights into the underlying protein stability changes that cause dramatic cellular phenotypes observed at nonpermissive temperatures. Overall, mTPP provides unique mechanistic insights into missense mutation dysfunction and connection of genotype to phenotype in a rapid, nonbiased fashion.
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Affiliation(s)
- Sarah A Peck Justice
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Monica P Barron
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Guihong D Qi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - H R Sagara Wijeratne
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - José F Victorino
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ed R Simpson
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, USA; Department of BioHealth Informatics, School of Informatics and Computing, Indiana University-Purdue University, Indianapolis, Indiana, USA; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Jonah Z Vilseck
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Aruna B Wijeratne
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| | - Amber L Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, Indiana, USA.
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19
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Yu F, Cao X, Liu G, Wang Q, Xia R, Zhang X, Xie Q. ESCRT-I Component VPS23A Is Targeted by E3 Ubiquitin Ligase XBAT35 for Proteasome-Mediated Degradation in Modulating ABA Signaling. MOLECULAR PLANT 2020; 13:1556-1569. [PMID: 32919085 DOI: 10.1016/j.molp.2020.09.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/10/2020] [Accepted: 09/08/2020] [Indexed: 05/28/2023]
Abstract
A myriad of abiotic stress responses in plants are controlled by abscisic acid (ABA) signaling. ABA receptors can be degraded by both the 26S proteasome pathway and vacuolar degradation pathway after processing via the endosomal sorting complex required for transport (ESCRT) proteins. Despite being essential for ABA signaling, the upstream regulators of ESCRTs remain unknown. Here, we report that the ESCRT-I component VPS23A is an unstable protein that is degraded via the ubiquitin-proteasome system (UPS). The UEV domain of VPS23A physically interacts with the two PSAP motifs of XBAT35, an E3 ubiquitin ligase, and this interaction results in the deposition of K48 polyubiquitin chains on VPS23A, marking it for degradation by 26S proteasomes. We showed that XBAT35 in plants is a positive regulator of ABA responses that acts via the VPS23A/PYL4 complex, specifically by accelerating VPS23A turnover and thereby increasing accumulation of the ABA receptor PYL4. This work deciphers how an ESCRT component is regulated in plants and deepens our understanding of plant stress responses by illustrating a mechanism whereby crosstalk between the UPS and endosome-vacuole-mediated degradation pathways controls ABA signaling.
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Affiliation(s)
- Feifei Yu
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China.
| | - Xiaoqiang Cao
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; University of the Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guangchao Liu
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; University of the Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Qian Wang
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; University of the Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Ran Xia
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Xiangyun Zhang
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; University of the Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Qi Xie
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; University of the Chinese Academy of Sciences, Beijing 100049, P. R. China.
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20
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Goebel T, Mausbach S, Tuermer A, Eltahir H, Winter D, Gieselmann V, Thelen M. Proteaphagy in Mammalian Cells Can Function Independent of ATG5/ATG7. Mol Cell Proteomics 2020; 19:1120-1131. [PMID: 32299840 PMCID: PMC7338089 DOI: 10.1074/mcp.ra120.001983] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/04/2020] [Indexed: 01/31/2023] Open
Abstract
The degradation of intra- and extracellular proteins is essential in all cell types and mediated by two systems, the ubiquitin-proteasome system (UPS) and the autophagy-lysosome pathway. This study investigates the changes in autophagosomal and lysosomal proteomes upon inhibition of proteasomes by bortezomib (BTZ) or MG132. We find an increased abundance of more than 50 proteins in lysosomes of cells in which the proteasome is inhibited. Among those are dihydrofolate reductase (DHFR), β-Catenin and 3-hydroxy-3-methylglutaryl-coenzym-A (HMGCoA)-reductase. Because these proteins are known to be degraded by the proteasome they seem to be compensatorily delivered to the autophagosomal pathway when the proteasome is inactivated. Surprisingly, most of the proteins which show increased amounts in the lysosomes of BTZ or MG132 treated cells are proteasomal subunits. Thus an inactivated, non-functional proteasome is delivered to the autophagic pathway. Native gel electrophoresis shows that the proteasome reaches the lysosome intact and not disassembled. Adaptor proteins, which target proteasomes to autophagy, have been described in Arabidopsis, Saccharomyces and upon starvation in mammalians. However, in cell lines deficient of these proteins or their mammalian orthologues, respectively, the transfer of proteasomes to the lysosome is not impaired. Obviously, these proteins do not play a role as autophagy adaptor proteins in mammalian cells. We can also show that chaperone-mediated autophagy (CMA) does not participate in the proteasome delivery to the lysosomes. In autophagy-related (ATG)-5 and ATG7 deficient cells the delivery of inactivated proteasomes to the autophagic pathway was only partially blocked, indicating the existence of at least two different pathways by which inactivated proteasomes can be delivered to the lysosome in mammalian cells.
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Affiliation(s)
- Tatjana Goebel
- Institute for Biochemistry and Molecular Biology, Medical Faculty, University of Bonn
| | - Simone Mausbach
- Institute for Biochemistry and Molecular Biology, Medical Faculty, University of Bonn
| | - Andreas Tuermer
- Institute for Biochemistry and Molecular Biology, Medical Faculty, University of Bonn
| | - Heba Eltahir
- Institute for Biochemistry and Molecular Biology, Medical Faculty, University of Bonn
| | - Dominic Winter
- Institute for Biochemistry and Molecular Biology, Medical Faculty, University of Bonn
| | - Volkmar Gieselmann
- Institute for Biochemistry and Molecular Biology, Medical Faculty, University of Bonn
| | - Melanie Thelen
- Institute for Biochemistry and Molecular Biology, Medical Faculty, University of Bonn.
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21
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Karmon O, Ben Aroya S. Spatial Organization of Proteasome Aggregates in the Regulation of Proteasome Homeostasis. Front Mol Biosci 2020; 6:150. [PMID: 31998748 PMCID: PMC6962763 DOI: 10.3389/fmolb.2019.00150] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 12/06/2019] [Indexed: 12/23/2022] Open
Abstract
Misfolded proteins and insoluble aggregates are continuously produced in the cell and can result in severe stress that threatens cellular fitness and viability if not managed effectively. Accordingly, organisms have evolved several protective protein quality control (PQC) machineries to address these threats. In eukaryotes, the ubiquitin–proteasome system (UPS) plays a vital role in the disposal of intracellular misfolded, damaged, or unneeded proteins. Although ubiquitin-mediated proteasomal degradation of many proteins plays a key role in the PQC system, cells must also dispose of the proteasomes themselves when their subunits are assembled improperly, or when they dysfunction under various conditions, e.g., as a result of genomic mutations, diverse stresses, or treatment with proteasome inhibitors. Here, we review recent studies that identified the regulatory pathways that mediate proteasomes sorting under various stress conditions, and the elimination of its dysfunctional subunits. Following inactivation of the 26S proteasome, UPS-mediated degradation of its own misassembled subunits is the favored disposal pathway. However, the cytosolic cell-compartment-specific aggregase, Hsp42 mediates an alternative pathway, the accumulation of these subunits in cytoprotective compartments, where they become extensively modified with ubiquitin, and are directed by ubiquitin receptors for autophagic clearance (proteaphagy). We also discuss the sorting mechanisms that the cell uses under nitrogen stress, and to distinguish between dysfunctional proteasome aggregates and proteasome storage granules (PSGs), reversible assemblies of membrane-free cytoplasmic condensates that form in yeast upon carbon starvation and help protect proteasomes from autophagic degradation. Regulated proteasome subunit homeostasis is thus controlled through cellular probing of the level of proteasome assembly, and the interplay between UPS-mediated degradation or sorting of misfolded proteins into distinct cellular compartments.
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Affiliation(s)
- Ofri Karmon
- The Mina and Everard Goodman, Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Shay Ben Aroya
- The Mina and Everard Goodman, Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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22
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Li J, Breker M, Graham M, Schuldiner M, Hochstrasser M. AMPK regulates ESCRT-dependent microautophagy of proteasomes concomitant with proteasome storage granule assembly during glucose starvation. PLoS Genet 2019; 15:e1008387. [PMID: 31738769 PMCID: PMC6886873 DOI: 10.1371/journal.pgen.1008387] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 12/02/2019] [Accepted: 11/07/2019] [Indexed: 12/14/2022] Open
Abstract
The ubiquitin-proteasome system regulates numerous cellular processes and is central to protein homeostasis. In proliferating yeast and many mammalian cells, proteasomes are highly enriched in the nucleus. In carbon-starved yeast, proteasomes migrate to the cytoplasm and collect in proteasome storage granules (PSGs). PSGs dissolve and proteasomes return to the nucleus within minutes of glucose refeeding. The mechanisms by which cells regulate proteasome homeostasis under these conditions remain largely unknown. Here we show that AMP-activated protein kinase (AMPK) together with endosomal sorting complexes required for transport (ESCRTs) drive a glucose starvation-dependent microautophagy pathway that preferentially sorts aberrant proteasomes into the vacuole, thereby biasing accumulation of functional proteasomes in PSGs. The proteasome core particle (CP) and regulatory particle (RP) are regulated differently. Without AMPK, the insoluble protein deposit (IPOD) serves as an alternative site that specifically sequesters CP aggregates. Our findings reveal a novel AMPK-controlled ESCRT-mediated microautophagy mechanism in the regulation of proteasome trafficking and homeostasis under carbon starvation.
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Affiliation(s)
- Jianhui Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Michal Breker
- Department of Molecular Genetics, Weizmann Institute of Sciences, Rehovot, Israel
| | - Morven Graham
- Center for Cellular and Molecular Imaging, School of Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Sciences, Rehovot, Israel
| | - Mark Hochstrasser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
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23
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The Proteasome Lid Triggers COP9 Signalosome Activity during the Transition of Saccharomyces cerevisiae Cells into Quiescence. Biomolecules 2019; 9:biom9090449. [PMID: 31487956 PMCID: PMC6770237 DOI: 10.3390/biom9090449] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 08/28/2019] [Accepted: 09/02/2019] [Indexed: 12/21/2022] Open
Abstract
The class of Cullin-RING E3 ligases (CRLs) selectively ubiquitinate a large portion of proteins targeted for proteolysis by the 26S proteasome. Before degradation, ubiquitin molecules are removed from their conjugated proteins by deubiquitinating enzymes, a handful of which are associated with the proteasome. The CRL activity is triggered by modification of the Cullin subunit with the ubiquitin-like protein, NEDD8 (also known as Rub1 in Saccharomyces cerevisiae). Cullin modification is then reversed by hydrolytic action of the COP9 signalosome (CSN). As the NEDD8-Rub1 catalytic cycle is not essential for the viability of S. cerevisiae, this organism is a useful model system to study the alteration of Rub1-CRL conjugation patterns. In this study, we describe two distinct mutants of Rpn11, a proteasome-associated deubiquitinating enzyme, both of which exhibit a biochemical phenotype characterized by high accumulation of Rub1-modified Cdc53-Cullin1 (yCul1) upon entry into quiescence in S. cerevisiae. Further characterization revealed proteasome 19S-lid-associated deubiquitination activity that authorizes the hydrolysis of Rub1 from yCul1 by the CSN complex. Thus, our results suggest a negative feedback mechanism via proteasome capacity on upstream ubiquitinating enzymes.
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24
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Morozov AV, Burov AV, Astakhova TM, Spasskaya DS, Margulis BA, Karpov VL. Dynamics of the Functional Activity and Expression of Proteasome Subunits during Cellular Adaptation to Heat Shock. Mol Biol 2019. [DOI: 10.1134/s0026893319040071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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25
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Marshall RS, Vierstra RD. Dynamic Regulation of the 26S Proteasome: From Synthesis to Degradation. Front Mol Biosci 2019; 6:40. [PMID: 31231659 PMCID: PMC6568242 DOI: 10.3389/fmolb.2019.00040] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 05/09/2019] [Indexed: 01/12/2023] Open
Abstract
All eukaryotes rely on selective proteolysis to control the abundance of key regulatory proteins and maintain a healthy and properly functioning proteome. Most of this turnover is catalyzed by the 26S proteasome, an intricate, multi-subunit proteolytic machine. Proteasomes recognize and degrade proteins first marked with one or more chains of poly-ubiquitin, the addition of which is actuated by hundreds of ligases that individually identify appropriate substrates for ubiquitylation. Subsequent proteasomal digestion is essential and influences a myriad of cellular processes in species as diverse as plants, fungi and humans. Importantly, dysfunction of 26S proteasomes is associated with numerous human pathologies and profoundly impacts crop performance, thus making an understanding of proteasome dynamics critically relevant to almost all facets of human health and nutrition. Given this widespread significance, it is not surprising that sophisticated mechanisms have evolved to tightly regulate 26S proteasome assembly, abundance and activity in response to demand, organismal development and stress. These include controls on transcription and chaperone-mediated assembly, influences on proteasome localization and activity by an assortment of binding proteins and post-translational modifications, and ultimately the removal of excess or damaged particles via autophagy. Intriguingly, the autophagic clearance of damaged 26S proteasomes first involves their modification with ubiquitin, thus connecting ubiquitylation and autophagy as key regulatory events in proteasome quality control. This turnover is also influenced by two distinct biomolecular condensates that coalesce in the cytoplasm, one attracting damaged proteasomes for autophagy, and the other reversibly storing proteasomes during carbon starvation to protect them from autophagic clearance. In this review, we describe the current state of knowledge regarding the dynamic regulation of 26S proteasomes at all stages of their life cycle, illustrating how protein degradation through this proteolytic machine is tightly controlled to ensure optimal growth, development and longevity.
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Affiliation(s)
- Richard S Marshall
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, MO, United States
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Mogk A, Ruger-Herreros C, Bukau B. Cellular Functions and Mechanisms of Action of Small Heat Shock Proteins. Annu Rev Microbiol 2019; 73:89-110. [PMID: 31091419 DOI: 10.1146/annurev-micro-020518-115515] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Small heat shock proteins (sHsps) constitute a diverse chaperone family that shares the α-crystallin domain, which is flanked by variable, disordered N- and C-terminal extensions. sHsps act as the first line of cellular defense against protein unfolding stress. They form dynamic, large oligomers that represent inactive storage forms. Stress conditions cause a rapid increase in cellular sHsp levels and trigger conformational rearrangements, resulting in exposure of substrate-binding sites and sHsp activation. sHsps bind to early-unfolding intermediates of misfolding proteins in an ATP-independent manner and sequester them in sHsp/substrate complexes. Sequestration protects substrates from further uncontrolled aggregation and facilitates their refolding by ATP-dependent Hsp70-Hsp100 disaggregases. Some sHsps with particularly strong sequestrase activity, such as yeast Hsp42, are critical factors for forming large, microscopically visible deposition sites of misfolded proteins in vivo. These sites are organizing centers for triaging substrates to distinct quality control pathways, preferentially Hsp70-dependent refolding and selective autophagy.
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Affiliation(s)
- Axel Mogk
- Center for Molecular Biology of the University of Heidelberg and German Cancer Research Center, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; ,
| | - Carmen Ruger-Herreros
- Center for Molecular Biology of the University of Heidelberg and German Cancer Research Center, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; ,
| | - Bernd Bukau
- Center for Molecular Biology of the University of Heidelberg and German Cancer Research Center, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; ,
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Proteostasis by STUB1/HSP70 complex controls sensitivity to androgen receptor targeted therapy in advanced prostate cancer. Nat Commun 2018; 9:4700. [PMID: 30446660 PMCID: PMC6240084 DOI: 10.1038/s41467-018-07178-x] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 10/11/2018] [Indexed: 02/06/2023] Open
Abstract
Protein homeostasis (proteostasis) is a potential mechanism that contributes to cancer cell survival and drug resistance. Constitutively active androgen receptor (AR) variants confer anti-androgen resistance in advanced prostate cancer. However, the role of proteostasis involved in next generation anti-androgen resistance and the mechanisms of AR variant regulation are poorly defined. Here we show that the ubiquitin-proteasome-system (UPS) is suppressed in enzalutamide/abiraterone resistant prostate cancer. AR/AR-V7 proteostasis requires the interaction of E3 ubiquitin ligase STUB1 and HSP70 complex. STUB1 disassociates AR/AR-V7 from HSP70, leading to AR/AR-V7 ubiquitination and degradation. Inhibition of HSP70 significantly inhibits prostate tumor growth and improves enzalutamide/abiraterone treatments through AR/AR-V7 suppression. Clinically, HSP70 expression is upregulated and correlated with AR/AR-V7 levels in high Gleason score prostate tumors. Our results reveal a novel mechanism of anti-androgen resistance via UPS alteration which could be targeted through inhibition of HSP70 to reduce AR-V7 expression and overcome resistance to AR-targeted therapies.
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Rothe S, Prakash A, Tyedmers J. The Insoluble Protein Deposit (IPOD) in Yeast. Front Mol Neurosci 2018; 11:237. [PMID: 30050408 PMCID: PMC6052365 DOI: 10.3389/fnmol.2018.00237] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/18/2018] [Indexed: 11/13/2022] Open
Abstract
The appearance of protein aggregates is a hallmark of several pathologies including many neurodegenerative diseases. Mounting evidence suggests that the accumulation of misfolded proteins into inclusions is a secondary line of defense when the extent of protein misfolding exceeds the capacity of the Protein Quality Control System, which mediates refolding or degradation of misfolded species. Such exhaustion can occur during severe proteotoxic stress, the excessive occurrence of aggregation prone protein species, e.g., amyloids, or during ageing. However, the machinery that mediates recognition, recruitment and deposition of different types of misfolded proteins into specific deposition sites is only poorly understood. Since emerging principles of aggregate deposition appear evolutionarily conserved, yeast represents a powerful model to study basic mechanisms of recognition of different types of misfolded proteins, their recruitment to the respective deposition site and the molecular organization at the corresponding site. Yeast possesses at least three different aggregate deposition sites, one of which is a major deposition site for amyloid aggregates termed Insoluble PrOtein Deposit (IPOD). Due to the link between neurodegenerative disease and accumulation of amyloid aggregates, the IPOD is of particular interest when we aim to identify the molecular mechanisms that cells have evolved to counteract toxicity associated with the occurrence of amyloid aggregates. Here, we will review what is known about IPOD composition and the mechanisms of recognition and recruitment of amyloid aggregates to this site in yeast. Finally, we will briefly discuss the possible physiological role of aggregate deposition at the IPOD.
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Affiliation(s)
- Stephanie Rothe
- Department of Medicine I and Clinical Chemistry, Heidelberg University Hospital, Heidelberg, Germany
| | - Abaya Prakash
- Department of Medicine I and Clinical Chemistry, Heidelberg University Hospital, Heidelberg, Germany
| | - Jens Tyedmers
- Department of Medicine I and Clinical Chemistry, Heidelberg University Hospital, Heidelberg, Germany
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Marshall RS, Vierstra RD. Proteasome storage granules protect proteasomes from autophagic degradation upon carbon starvation. eLife 2018; 7:34532. [PMID: 29624167 PMCID: PMC5947986 DOI: 10.7554/elife.34532] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 04/05/2018] [Indexed: 12/14/2022] Open
Abstract
26S proteasome abundance is tightly regulated at multiple levels, including the elimination of excess or inactive particles by autophagy. In yeast, this proteaphagy occurs upon nitrogen starvation but not carbon starvation, which instead stimulates the rapid sequestration of proteasomes into cytoplasmic puncta termed proteasome storage granules (PSGs). Here, we show that PSGs help protect proteasomes from autophagic degradation. Both the core protease and regulatory particle sub-complexes are sequestered separately into PSGs via pathways dependent on the accessory proteins Blm10 and Spg5, respectively. Modulating PSG formation, either by perturbing cellular energy status or pH, or by genetically eliminating factors required for granule assembly, not only influences the rate of proteasome degradation, but also impacts cell viability upon recovery from carbon starvation. PSG formation and concomitant protection against proteaphagy also occurs in Arabidopsis, suggesting that PSGs represent an evolutionarily conserved cache of proteasomes that can be rapidly re-mobilized based on energy availability. Proteins perform many jobs within an organism, including providing structure and support, and protecting against infection. The levels of the many proteins in a cell need to be carefully controlled so that the correct amounts are present at the right place and time to perform these tasks. This control can be achieved by balancing the production of new proteins with the break down (or degradation) of proteins that are no longer required or become dysfunctional. Most cells have two pathways for degrading proteins. One pathway breaks down individual proteins specifically marked for elimination; this causes them to be recognized by a structure called the proteasome, which chops proteins into smaller pieces. Larger protein assemblies – including the proteasome itself – are to big for the proteasome and thus need to be degraded by another pathway called autophagy. This process engulfs and delivers parts of a cell to a membrane-bound compartment called the vacuole, which ‘digests’ and recycles these larger constituents. Proteasomes are degraded by autophagy when they are not working correctly and when nitrogen (a crucial nutrient) is in short supply. However, proteasomes are not degraded when cells lack carbon, even though this starvation is known to activate autophagy in the same way that an absence of nitrogen does. So how do proteasomes escape degradation when cells are starved for carbon? Marshall and Vierstra now show that upon carbon starvation, proteasomes rapidly exit the cell nucleus and cluster together in the main part of the cell (termed the cytosol). These clusters are known as proteasome storage granules (PSGs). In fungi and plants, mutations or conditions inside the cell that make it difficult for PSGs to assemble cause proteasomes to instead be broken down in the vacuole when carbon availability is low. Clustering into PSGs therefore protects proteasomes from autophagy. This clustering appears advantageous to cells; yeast cells that could form PSGs were better able to start growing again when their nutrient supply improved. Protein clustering (also known as aggregation) is an important strategy that cells use to survive stressful conditions. However, it can also be harmful when proteins aggregate inappropriately, such as occurs in Alzheimer’s disease. Researchers may be able to use PSG assembly as a convenient model to study the causes and consequences of protein aggregation; this knowledge could ultimately be applied to improve human health and crop productivity.
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Affiliation(s)
- Richard S Marshall
- Department of Biology, Washington University in St. Louis, St. Louis, United States
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, United States
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Co-translational control of protein complex formation: a fundamental pathway of cellular organization? Biochem Soc Trans 2018; 46:197-206. [PMID: 29432142 DOI: 10.1042/bst20170451] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 12/10/2017] [Accepted: 01/08/2018] [Indexed: 12/16/2022]
Abstract
Analyses of proteomes from a large number of organisms throughout the domains of life highlight the key role played by multiprotein complexes for the implementation of cellular function. While the occurrence of multiprotein assemblies is ubiquitous, the understanding of pathways that dictate the formation of quaternary structure remains enigmatic. Interestingly, there are now well-established examples of protein complexes that are assembled co-translationally in both prokaryotes and eukaryotes, and indications are that the phenomenon is widespread in cells. Here, we review complex assembly with an emphasis on co-translational pathways, which involve interactions of nascent chains with other nascent or mature partner proteins, respectively. In prokaryotes, such interactions are promoted by the polycistronic arrangement of mRNA and the associated co-translation of functionally related cell constituents in order to enhance otherwise diffusion-dependent processes. Beyond merely stochastic events, however, co-translational complex formation may be sensitive to subunit availability and allow for overall regulation of the assembly process. We speculate how co-translational pathways may constitute integral components of quality control systems to ensure the correct and complete formation of hundreds of heterogeneous assemblies in a single cell. Coupling of folding of intrinsically disordered domains with co-translational interaction of binding partners may furthermore enhance the efficiency and fidelity with which correct conformation is attained. Co-translational complex formation may constitute a fundamental pathway of cellular organization, with profound importance for health and disease.
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Grousl T, Ungelenk S, Miller S, Ho CT, Khokhrina M, Mayer MP, Bukau B, Mogk A. A prion-like domain in Hsp42 drives chaperone-facilitated aggregation of misfolded proteins. J Cell Biol 2018; 217:1269-1285. [PMID: 29362223 PMCID: PMC5881502 DOI: 10.1083/jcb.201708116] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 12/07/2017] [Accepted: 01/08/2018] [Indexed: 12/31/2022] Open
Abstract
The facilitated aggregation of misfolded proteins is a proteostasis strategy important for cell function and viability, but the molecular mechanisms are poorly understood. Grousl et al. reveal how the intrinsically disordered domains of the small heat shock protein Hsp42 promote and control the aggregation of misfolded proteins during stress conditions in yeast. Chaperones with aggregase activity promote and organize the aggregation of misfolded proteins and their deposition at specific intracellular sites. This activity represents a novel cytoprotective strategy of protein quality control systems; however, little is known about its mechanism. In yeast, the small heat shock protein Hsp42 orchestrates the stress-induced sequestration of misfolded proteins into cytosolic aggregates (CytoQ). In this study, we show that Hsp42 harbors a prion-like domain (PrLD) and a canonical intrinsically disordered domain (IDD) that act coordinately to promote and control protein aggregation. Hsp42 PrLD is essential for CytoQ formation and is bifunctional, mediating self-association as well as binding to misfolded proteins. Hsp42 IDD confines chaperone and aggregase activity and affects CytoQ numbers and stability in vivo. Hsp42 PrLD and IDD are both crucial for cellular fitness during heat stress, demonstrating the need for sequestering misfolded proteins in a regulated manner.
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Affiliation(s)
- Tomas Grousl
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Sophia Ungelenk
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Stephanie Miller
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Chi-Ting Ho
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Maria Khokhrina
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Matthias P Mayer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Bernd Bukau
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany .,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Axel Mogk
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany .,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
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There Is an Inclusion for That: Material Properties of Protein Granules Provide a Platform for Building Diverse Cellular Functions. Trends Biochem Sci 2017; 42:765-776. [DOI: 10.1016/j.tibs.2017.08.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/26/2017] [Accepted: 08/03/2017] [Indexed: 12/30/2022]
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Gu ZC, Wu E, Sailer C, Jando J, Styles E, Eisenkolb I, Kuschel M, Bitschar K, Wang X, Huang L, Vissa A, Yip CM, Yedidi RS, Friesen H, Enenkel C. Ubiquitin orchestrates proteasome dynamics between proliferation and quiescence in yeast. Mol Biol Cell 2017; 28:2479-2491. [PMID: 28768827 PMCID: PMC5597321 DOI: 10.1091/mbc.e17-03-0162] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/16/2017] [Accepted: 07/24/2017] [Indexed: 12/14/2022] Open
Abstract
Proteasomes are key protease complexes responsible for protein degradation, and their localization changes with the growth conditions. This work in yeast shows that proteasomes exit the nucleus with the transition from proliferation to quiescence. Ubiquitin is a key player in proteasome dynamics and cytoplasmic proteasome granule formation. Proteasomes are essential for protein degradation in proliferating cells. Little is known about proteasome functions in quiescent cells. In nondividing yeast, a eukaryotic model of quiescence, proteasomes are depleted from the nucleus and accumulate in motile cytosolic granules termed proteasome storage granules (PSGs). PSGs enhance resistance to genotoxic stress and confer fitness during aging. Upon exit from quiescence PSGs dissolve, and proteasomes are rapidly delivered into the nucleus. To identify key players in PSG organization, we performed high-throughput imaging of green fluorescent protein (GFP)-labeled proteasomes in the yeast null-mutant collection. Mutants with reduced levels of ubiquitin are impaired in PSG formation. Colocalization studies of PSGs with proteins of the yeast GFP collection, mass spectrometry, and direct stochastic optical reconstitution microscopy of cross-linked PSGs revealed that PSGs are densely packed with proteasomes and contain ubiquitin but no polyubiquitin chains. Our results provide insight into proteasome dynamics between proliferating and quiescent yeast in response to cellular requirements for ubiquitin-dependent degradation.
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Affiliation(s)
- Zhu Chao Gu
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Edwin Wu
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Carolin Sailer
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Julia Jando
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Erin Styles
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Ina Eisenkolb
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Maike Kuschel
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Katharina Bitschar
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Xiaorong Wang
- Department of Physics and Biophysics, University of California, Irvine, Irvine, CA 92697
| | - Lan Huang
- Department of Physics and Biophysics, University of California, Irvine, Irvine, CA 92697
| | - Adriano Vissa
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Christopher M Yip
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada.,Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Ravikiran S Yedidi
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Helena Friesen
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Cordula Enenkel
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
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Mogk A, Bukau B. Role of sHsps in organizing cytosolic protein aggregation and disaggregation. Cell Stress Chaperones 2017; 22:493-502. [PMID: 28120291 PMCID: PMC5465027 DOI: 10.1007/s12192-017-0762-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 11/29/2022] Open
Abstract
Small heat shock proteins (sHsps) exhibit an ATP-independent chaperone activity to prevent the aggregation of misfolded proteins in vitro. The seemingly conflicting presence of sHsps in insoluble protein aggregates in cells obstructs a precise definition of sHsp function in proteostasis networks. Recent findings specify sHsp activities in protein quality control systems. The sHsps of yeast, Hsp42 and Hsp26, interact with early unfolding intermediates of substrates, keeping them in a ready-to-refold conformation close to the native state. This activity facilitates substrate refolding by ATP-dependent Hsp70-Hsp100 disaggregating chaperones. Hsp42 can actively sequester misfolded proteins and promote their deposition at specific cellular sites. This aggregase activity represents a cytoprotective protein quality control strategy. The aggregase function of Hsp42 controls the formation of cytosolic aggregates (CytoQs) under diverse stress regimes and can be reconstituted in vitro, demonstrating that Hsp42 is necessary and sufficient to promote protein aggregation. Substrates sequestered at CytoQs can be dissociated by Hsp70-Hsp100 disaggregases for subsequent triage between refolding and degradation pathways or are targeted for destruction by selective autophagy termed proteophagy.
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Affiliation(s)
- Axel Mogk
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany.
- German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
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Kumar R, Neuser N, Tyedmers J. Hitchhiking vesicular transport routes to the vacuole: Amyloid recruitment to the Insoluble Protein Deposit (IPOD). Prion 2017; 11:71-81. [PMID: 28277942 PMCID: PMC5399893 DOI: 10.1080/19336896.2017.1293226] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sequestration of aggregates into specialized deposition sites occurs in many species across all kingdoms of life ranging from bacteria to mammals and is commonly believed to have a cytoprotective function. Yeast cells possess at least 3 different spatially separated deposition sites, one of which is termed “Insoluble Protein Deposit (IPOD)” and harbors amyloid aggregates. We have recently discovered that recruitment of amyloid aggregates to the IPOD uses an actin cable based recruitment machinery that also involves vesicular transport.1 Here we discuss how different proteins known to be involved in vesicular transport processes to the vacuole might act to guide amyloid aggregates to the IPOD. These factors include the Myosin V motor protein Myo2 involved in transporting vacuolar vesicles along actin cables, the transmembrane protein Atg9 involved in the recruitment of large precursor hydrolase complexes to the vacuole, the phosphatidylinositol/ phosphatidylcholine (PI/PC) transfer protein Sec 14 and the SNARE chaperone Sec 18. Furthermore, we present new data suggesting that the yeast dynamin homolog Vps1 is also crucial for faithful delivery of the amyloid model protein PrD-GFP to the IPOD. This is in agreement with a previously identified role for Vps1 in recruitment of heat-denatured aggregates to a perivacuolar deposition site.2
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Affiliation(s)
- Rajesh Kumar
- a Department of Medicine I and Clinical Chemistry , University Hospital Heidelberg , Heidelberg , Germany
| | - Nicole Neuser
- a Department of Medicine I and Clinical Chemistry , University Hospital Heidelberg , Heidelberg , Germany
| | - Jens Tyedmers
- a Department of Medicine I and Clinical Chemistry , University Hospital Heidelberg , Heidelberg , Germany
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36
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Howell LA, Tomko RJ, Kusmierczyk AR. Putting it all together: intrinsic and extrinsic mechanisms governing proteasome biogenesis. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/s11515-017-1439-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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37
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Küry S, Besnard T, Ebstein F, Khan TN, Gambin T, Douglas J, Bacino CA, Craigen WJ, Sanders SJ, Lehmann A, Latypova X, Khan K, Pacault M, Sacharow S, Glaser K, Bieth E, Perrin-Sabourin L, Jacquemont ML, Cho MT, Roeder E, Denommé-Pichon AS, Monaghan KG, Yuan B, Xia F, Simon S, Bonneau D, Parent P, Gilbert-Dussardier B, Odent S, Toutain A, Pasquier L, Barbouth D, Shaw CA, Patel A, Smith JL, Bi W, Schmitt S, Deb W, Nizon M, Mercier S, Vincent M, Rooryck C, Malan V, Briceño I, Gómez A, Nugent KM, Gibson JB, Cogné B, Lupski JR, Stessman HA, Eichler EE, Retterer K, Yang Y, Redon R, Katsanis N, Rosenfeld JA, Kloetzel PM, Golzio C, Bézieau S, Stankiewicz P, Isidor B. De Novo Disruption of the Proteasome Regulatory Subunit PSMD12 Causes a Syndromic Neurodevelopmental Disorder. Am J Hum Genet 2017; 100:352-363. [PMID: 28132691 DOI: 10.1016/j.ajhg.2017.01.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/04/2017] [Indexed: 10/25/2022] Open
Abstract
Degradation of proteins by the ubiquitin-proteasome system (UPS) is an essential biological process in the development of eukaryotic organisms. Dysregulation of this mechanism leads to numerous human neurodegenerative or neurodevelopmental disorders. Through a multi-center collaboration, we identified six de novo genomic deletions and four de novo point mutations involving PSMD12, encoding the non-ATPase subunit PSMD12 (aka RPN5) of the 19S regulator of 26S proteasome complex, in unrelated individuals with intellectual disability, congenital malformations, ophthalmologic anomalies, feeding difficulties, deafness, and subtle dysmorphic facial features. We observed reduced PSMD12 levels and an accumulation of ubiquitinated proteins without any impairment of proteasome catalytic activity. Our PSMD12 loss-of-function zebrafish CRISPR/Cas9 model exhibited microcephaly, decreased convolution of the renal tubules, and abnormal craniofacial morphology. Our data support the biological importance of PSMD12 as a scaffolding subunit in proteasome function during development and neurogenesis in particular; they enable the definition of a neurodevelopmental disorder due to PSMD12 variants, expanding the phenotypic spectrum of UPS-dependent disorders.
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38
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Cohen-Kaplan V, Livneh I, Avni N, Fabre B, Ziv T, Kwon YT, Ciechanover A. p62- and ubiquitin-dependent stress-induced autophagy of the mammalian 26S proteasome. Proc Natl Acad Sci U S A 2016; 113:E7490-E7499. [PMID: 27791183 PMCID: PMC5127335 DOI: 10.1073/pnas.1615455113] [Citation(s) in RCA: 189] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ubiquitin-proteasome system and autophagy are the two main proteolytic systems involved in, among other functions, the maintenance of cell integrity by eliminating misfolded and damaged proteins and organelles. Both systems remove their targets after their conjugation with ubiquitin. An interesting, yet incompletely understood problem relates to the fate of the components of the two systems. Here we provide evidence that amino acid starvation enhances polyubiquitination on specific sites of the proteasome, a modification essential for its targeting to the autophagic machinery. The uptake of the ubiquitinated proteasome is mediated by its interaction with the ubiquitin-associated domain of p62/SQSTM1, a process that also requires interaction with LC3. Importantly, deletion of the PB1 domain of p62, which is important for the targeting of ubiquitinated substrates to the proteasome, has no effect on stress-induced autophagy of this proteolytic machinery, suggesting that the domain of p62 that binds to the proteasome determines the function of p62 in either targeting substrates to the proteasome or targeting the proteasome to autophagy.
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Affiliation(s)
- Victoria Cohen-Kaplan
- Technion Integrated Cancer Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109602, Israel
| | - Ido Livneh
- Technion Integrated Cancer Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109602, Israel
| | - Noa Avni
- Technion Integrated Cancer Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109602, Israel
| | - Bertrand Fabre
- Technion Integrated Cancer Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109602, Israel
| | - Tamar Ziv
- Smoler Proteomic Center and Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Yong Tae Kwon
- Protein Metabolism Medical Research Center and Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul 03080, Korea
| | - Aaron Ciechanover
- Technion Integrated Cancer Center, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa 3109602, Israel;
- Protein Metabolism Medical Research Center and Department of Biomedical Sciences, College of Medicine, Seoul National University, Seoul 03080, Korea
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39
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Mayor T, Sharon M, Glickman MH. Tuning the proteasome to brighten the end of the journey. Am J Physiol Cell Physiol 2016; 311:C793-C804. [PMID: 27605452 DOI: 10.1152/ajpcell.00198.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/04/2016] [Indexed: 02/07/2023]
Abstract
Degradation by the proteasome is the fate for a large portion of cellular proteins, and it plays a major role in maintaining protein homeostasis, as well as in regulating many cellular processes like cell cycle progression. A decrease in proteasome activity has been linked to aging and several age-related neurodegenerative pathologies and highlights the importance of the ubiquitin proteasome system regulation. While the proteasome has been traditionally viewed as a constitutive element of proteolysis, major studies have highlighted how different regulatory mechanisms can impact its activity. Importantly, alterations of proteasomal activity may have major impacts for its function and in therapeutics. On one hand, increasing proteasome activity could be beneficial to prevent the age-related downfall of protein homeostasis, whereas inhibiting or reducing its activity can prevent the proliferation of cancer cells.
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Affiliation(s)
- Thibault Mayor
- Department of Biochemistry and Molecular Biology, Michael Smith Laboratories, University of British Columbia, Vancouver, Canada;
| | - Michal Sharon
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel; and
| | - Michael H Glickman
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
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40
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Zhang C, Lu J, Zhang QW, Zhao W, Guo JH, Liu SL, Wu YL, Jiang B, Gao FH. USP7 promotes cell proliferation through the stabilization of Ki-67 protein in non-small cell lung cancer cells. Int J Biochem Cell Biol 2016; 79:209-221. [PMID: 27590858 DOI: 10.1016/j.biocel.2016.08.025] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 08/07/2016] [Accepted: 08/29/2016] [Indexed: 10/21/2022]
Abstract
The Ki-67 antigen (Ki-67) is the most reliable immunohistochemical marker for evaluation of cell proliferation in non-small cell lung cancer. However, the mechanisms underlying the regulation of protein levels of Ki-67 in non-small cell lung cancer have remained elusive. In this study, we found that Ki-67 and ubiquitin-specific processing protease 7 (USP7) protein were highly expressed in the nucleus of non-small cell lung cancer cells. Furthermore, statistical analysis uncovered the existence of a strong correlation between Ki-67 and USP7 levels. We could also show that the protein levels of Ki-67 in non-small cell lung cancer cells significantly decreased after treatment with P22077, a selective chemical inhibitor of USP7, while the Ki-67 mRNA levels were unperturbed. Similar results were obtained by knocking down USP7 using short hairpin RNA (shRNA) in lung cancer cells. Interestingly, we noticed that ubiquitination levels of Ki-67 increased dramatically in USP7-silenced cells. The tests in vitro and vivo showed a significant delay in tumor cell growth upon knockdown of USP7. Additionally, drug sensitivity tests indicated that USP7-silenced A549 cells had enhanced sensitivity to paclitaxel and docetaxel, while there was no significant change in sensitivity toward carboplatin and cisplatin. Taken together, these data strongly suggest that the overexpression of USP7 might promote cell proliferation by deubiquitinating Ki-67 protein, thereby maintaining its high levels in the non-small cell lung cancer. Our study also hints potential for the development of deubiquitinase-based therapies, especially those targeting USP7 to improve the condition of patients diagnosed with non-small cell lung cancer.
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Affiliation(s)
- Chao Zhang
- Department of Oncology, Shanghai 9th People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhi Zao Ju Rd, Shanghai 200011, China
| | - Jing Lu
- Department of Oncology, Shanghai 9th People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhi Zao Ju Rd, Shanghai 200011, China
| | - Quan-Wu Zhang
- Department of Pathology, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou 450007, China
| | - Wei Zhao
- Department of Pathology, The First People's Hospital of Changzhou (The Third Affiliated Hospital of Soochow University), Changzhou 213003, China
| | - Jia-Hui Guo
- Department of Oncology, Shanghai 9th People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhi Zao Ju Rd, Shanghai 200011, China
| | - Shan-Ling Liu
- Department of Oncology, Shanghai 9th People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhi Zao Ju Rd, Shanghai 200011, China
| | - Ying-Li Wu
- Hongqiao International Institute of Medicine, Shanghai Tongren Hospital/Faculty of Basic Medicine, Chemical Biology Division of Shanghai Universities E-Institutes, Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Bin Jiang
- Department of Oncology, Shanghai 9th People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhi Zao Ju Rd, Shanghai 200011, China.
| | - Feng-Hou Gao
- Department of Oncology, Shanghai 9th People's Hospital, Shanghai Jiao Tong University School of Medicine, 639 Zhi Zao Ju Rd, Shanghai 200011, China.
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41
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Kaminska J, Rzepnikowska W, Polak A, Flis K, Soczewka P, Bala K, Sienko M, Grynberg M, Kaliszewski P, Urbanek A, Ayscough K, Zoladek T. Phosphatidylinositol-3-phosphate regulates response of cells to proteotoxic stress. Int J Biochem Cell Biol 2016; 79:494-504. [PMID: 27498190 DOI: 10.1016/j.biocel.2016.08.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 07/29/2016] [Accepted: 08/03/2016] [Indexed: 12/22/2022]
Abstract
Human Nedd4 ubiquitin ligase, or its variants, inhibit yeast cell growth by disturbing the actin cytoskeleton organization and dynamics, and lead to an increase in levels of ubiquitinated proteins. In a screen for multicopy suppressors which rescue growth of yeast cells producing Nedd4 ligase with an inactive WW4 domain (Nedd4w4), we identified a fragment of ATG2 gene encoding part of the Atg2 core autophagy protein. Expression of the Atg2-C1 fragment (aa 1074-1447) improved growth, actin cytoskeleton organization, but did not significantly change the levels of ubiquitinated proteins in these cells. The GFP-Atg2-C1 protein in Nedd4w4-producing cells primarily localized to a single defined structure adjacent to the vacuole, surrounded by an actin filament ring, containing Hsp42 and Hsp104 chaperones. This localization was not affected in several atg deletion mutants, suggesting that it might be distinct from the phagophore assembly site (PAS). However, deletion of ATG18 encoding a phosphatidylinositol-3-phosphate (PI3P)-binding protein affected the morphology of the GFP-Atg2-C1 structure while deletion of ATG14 encoding a subunit of PI3 kinase suppressed toxicity of Nedd4w4 independently of GFP-Atg2-C1. Further analysis of the Atg2-C1 revealed that it contains an APT1 domain of previously uncharacterized function. Most importantly, we showed that this domain is able to bind phosphatidylinositol phosphates, especially PI3P, which is abundant in the PAS and endosomes. Together our results suggest that human Nedd4 ubiquitinates proteins in yeast and causes proteotoxic stress and, with some Atg proteins, leads to formation of a perivacuolar structure, which may be involved in sequestration, aggregation or degradation of proteins.
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Affiliation(s)
- Joanna Kaminska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Weronika Rzepnikowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Anna Polak
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Krzysztof Flis
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Piotr Soczewka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Katarzyna Bala
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Marzena Sienko
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Marcin Grynberg
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Pawel Kaliszewski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Agnieszka Urbanek
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Kathryn Ayscough
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Teresa Zoladek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02-106 Warsaw, Poland.
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42
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Marshall RS, McLoughlin F, Vierstra RD. Autophagic Turnover of Inactive 26S Proteasomes in Yeast Is Directed by the Ubiquitin Receptor Cue5 and the Hsp42 Chaperone. Cell Rep 2016; 16:1717-1732. [PMID: 27477278 DOI: 10.1016/j.celrep.2016.07.015] [Citation(s) in RCA: 118] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/23/2016] [Accepted: 07/03/2016] [Indexed: 10/21/2022] Open
Abstract
The autophagic clearance of 26S proteasomes (proteaphagy) is an important homeostatic mechanism within the ubiquitin system that modulates proteolytic capacity and eliminates damaged particles. Here, we define two proteaphagy routes in yeast that respond to either nitrogen starvation or particle inactivation. Whereas the core autophagic machineries required for Atg8 lipidation and vesiculation are essential for both routes, the upstream Atg1 kinase participates only in starvation-induced proteaphagy. Following inactivation, 26S proteasomes become extensively modified with ubiquitin. Although prior studies with Arabidopsis implicated RPN10 in tethering ubiquitylated proteasomes to ATG8 lining the autophagic membranes, yeast proteaphagy employs the evolutionarily distinct receptor Cue5, which simultaneously binds ubiquitin and Atg8. Proteaphagy of inactivated proteasomes also requires the oligomeric Hsp42 chaperone, suggesting that ubiquitylated proteasomes are directed by Hsp42 to insoluble protein deposit (IPOD)-type structures before encapsulation. Together, Cue5 and Hsp42 provide a quality control checkpoint in yeast directed at recycling dysfunctional 26S proteasomes.
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Affiliation(s)
- Richard S Marshall
- Department of Genetics, University of Wisconsin, 425 Henry Mall, Madison, WI 53706, USA; Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
| | - Fionn McLoughlin
- Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
| | - Richard D Vierstra
- Department of Genetics, University of Wisconsin, 425 Henry Mall, Madison, WI 53706, USA; Department of Biology, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA.
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43
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The life cycle of the 26S proteasome: from birth, through regulation and function, and onto its death. Cell Res 2016; 26:869-85. [PMID: 27444871 PMCID: PMC4973335 DOI: 10.1038/cr.2016.86] [Citation(s) in RCA: 235] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The 26S proteasome is a large, ∼2.5 MDa, multi-catalytic ATP-dependent protease complex that serves as the degrading arm of the ubiquitin system, which is the major pathway for regulated degradation of cytosolic, nuclear and membrane proteins in all eukaryotic organisms.
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44
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Peters LZ, Karmon O, Miodownik S, Ben-Aroya S. Proteasome storage granules are transiently associated with the insoluble protein deposit (IPOD). J Cell Sci 2016; 129:1190-7. [DOI: 10.1242/jcs.179648] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/26/2016] [Indexed: 12/28/2022] Open
Abstract
Proteasome storage granules (PSGs) are created in yeast as part of an extensive, programmed reorganization of proteins into reversible assemblies, upon carbon source depletion. Here, we demonstrate that cells distinguish dysfunctional proteasomes from PSGs on the cytosolic insoluble protein deposit (IPOD). Furthermore, we provide evidence that this is a general mechanism for the reorganization of additional proteins into reversible assemblies. Our study expands the roles of the IPOD which may serve not only as the specific depository for amyloidogenic and misfolded proteins, but also as a potential hub, from which proteins are directed to distinct cellular compartments. These findings therefore provide a framework for understanding how cells discriminate between intact and abnormal proteins under stress conditions to ensure that only structurally ‘correct’ proteins are deployed.
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Affiliation(s)
- Lee Zeev Peters
- Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
| | - Ofri Karmon
- Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
| | - Shir Miodownik
- Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
| | - Shay Ben-Aroya
- Faculty of Life Sciences Bar-Ilan University, Ramat-Gan, Israel
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45
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Waite KA, De-La Mota-Peynado A, Vontz G, Roelofs J. Starvation Induces Proteasome Autophagy with Different Pathways for Core and Regulatory Particles. J Biol Chem 2015; 291:3239-53. [PMID: 26670610 PMCID: PMC4751371 DOI: 10.1074/jbc.m115.699124] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Indexed: 12/21/2022] Open
Abstract
The proteasome is responsible for the degradation of many cellular proteins. If and how this abundant and normally stable complex is degraded by cells is largely unknown. Here we show that in yeast, upon nitrogen starvation, proteasomes are targeted for vacuolar degradation through autophagy. Using GFP-tagged proteasome subunits, we observed that autophagy of a core particle (CP) subunit depends on the deubiquitinating enzyme Ubp3, although a regulatory particle (RP) subunit does not. Furthermore, upon blocking of autophagy, RP remained largely nuclear, although CP largely localized to the cytosol as well as granular structures within the cytosol. In all, our data reveal a regulated process for the removal of proteasomes upon nitrogen starvation. This process involves CP and RP dissociation, nuclear export, and independent vacuolar targeting of CP and RP. Thus, in addition to the well characterized transcriptional up-regulation of genes encoding proteasome subunits, cells are also capable of down-regulating cellular levels of proteasomes through proteaphagy.
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Affiliation(s)
- Kenrick A Waite
- From the Division of Biology, Kansas State University, Manhattan, Kansas 66506
| | | | - Gabrielle Vontz
- From the Division of Biology, Kansas State University, Manhattan, Kansas 66506
| | - Jeroen Roelofs
- From the Division of Biology, Kansas State University, Manhattan, Kansas 66506
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46
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Upadhyay A, Amanullah A, Chhangani D, Mishra R, Mishra A. Selective multifaceted E3 ubiquitin ligases barricade extreme defense: Potential therapeutic targets for neurodegeneration and ageing. Ageing Res Rev 2015; 24:138-59. [PMID: 26247845 DOI: 10.1016/j.arr.2015.07.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 06/24/2015] [Accepted: 07/30/2015] [Indexed: 12/24/2022]
Abstract
Efficient and regular performance of Ubiquitin Proteasome System and Autophagy continuously eliminate deleterious accumulation of nonnative protiens. In cellular quality control system, E3 ubiquitin ligases are significant employees for defense mechanism against abnormal toxic proteins. Few findings indicate that lack of functions of E3 ubiquitin ligases can be a causative factor of neurodevelopmental disorders, neurodegeneration, cancer and ageing. However, the detailed molecular pathomechanism implying E3 ubiquitin ligases in cellular functions in multifactorial disease conditions are not well understood. This article systematically represents the unique characteristics, molecular nature, and recent developments in the knowledge of neurobiological functions of few crucial E3 ubiquitin ligases. Here, we review recent literature on the roles of E6-AP, HRD1 and ITCH E3 ubiquitin ligases in the neuro-pathobiological mechanisms, with precise focus on the processes of neurodegeneration, and thereby propose new lines of potential targets for therapeutic interventions.
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47
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Liepe J, Holzhütter HG, Bellavista E, Kloetzel PM, Stumpf MPH, Mishto M. Quantitative time-resolved analysis reveals intricate, differential regulation of standard- and immuno-proteasomes. eLife 2015; 4:e07545. [PMID: 26393687 PMCID: PMC4611054 DOI: 10.7554/elife.07545] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 09/18/2015] [Indexed: 12/15/2022] Open
Abstract
Proteasomal protein degradation is a key determinant of protein half-life and hence of cellular processes ranging from basic metabolism to a host of immunological processes. Despite its importance the mechanisms regulating proteasome activity are only incompletely understood. Here we use an iterative and tightly integrated experimental and modelling approach to develop, explore and validate mechanistic models of proteasomal peptide-hydrolysis dynamics. The 20S proteasome is a dynamic enzyme and its activity varies over time because of interactions between substrates and products and the proteolytic and regulatory sites; the locations of these sites and the interactions between them are predicted by the model, and experimentally supported. The analysis suggests that the rate-limiting step of hydrolysis is the transport of the substrates into the proteasome. The transport efficiency varies between human standard- and immuno-proteasomes thereby impinging upon total degradation rate and substrate cleavage-site usage. DOI:http://dx.doi.org/10.7554/eLife.07545.001 Cells have to be able to reliably destroy or remove molecules from their interior that they no longer need. Structures called proteasomes play a central part in this complex process by cutting up and digesting proteins. Mammals have several different types of proteasomes, each made up of several protein ‘subunits’. For example, when a cell experiences inflammation some proteasomes change some of their subunits and form an immuno-proteasome. These immuno-proteasomes tend to break down proteins more quickly than ‘standard’ proteasomes, but it was not clear how they are able to do so. Liepe et al. have now combined experiments and mathematical modelling to construct a detailed model of proteasome activity. The model shows that protein transport into and out of the proteasome chamber are the steps that limit how quickly the proteasomes can break down proteins. Furthermore, these transport processes are also to a large extent responsible for the different rates at which standard and immuno-proteasomes process proteins. Liepe et al. were also able to confirm the existence of regulatory sites within the proteasome, and describe how these are arranged. Problems that alter the rate at which proteasomes break down proteins have been linked to tumors and neurological and autoimmune diseases. Liepe et al.'s model opens up the ability to study how the proteasome's activity is affected by drugs and therefore makes it easier to investigate ways of interfering with this activity for therapeutic purposes. DOI:http://dx.doi.org/10.7554/eLife.07545.002
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Affiliation(s)
- Juliane Liepe
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, United Kingdom
| | | | - Elena Bellavista
- Department of Experimental, Diagnostic and Specialty Medicine, Alma Mater Studiorum, University of Bologna, Bologna, Italy
| | - Peter M Kloetzel
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Michael P H Stumpf
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Michele Mishto
- Institut für Biochemie, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Luigi Galvani, Alma Mater Studiorum, University of Bologna, Bologna, Italy
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