1
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Lei Y, Uoselis L, Dialynaki D, Yang Y, Lazarou M, Klionsky DJ. Cancer-associated mutations in autophagy-related proteins analyzed in yeast and human cells. Autophagy 2025:1-17. [PMID: 40017376 DOI: 10.1080/15548627.2025.2471142] [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: 05/09/2024] [Revised: 01/14/2025] [Accepted: 02/10/2025] [Indexed: 03/01/2025] Open
Abstract
Macroautophagy/autophagy is a conserved process among eukaryotes and is essential to maintain cell homeostasis; the dysregulation of autophagy has been linked with multiple human diseases, including cancer. However, not many studies have focused on the cancer-related mutations in ATG (autophagy related) proteins, which are likely to affect the protein function, influence autophagy activity and further contribute to the progression of the disease. In this study, we focused on the four ATG4 isoforms, which have a higher mutation frequency compared with the other core ATG proteins (i.e. those involved in autophagosome formation). We first studied the mutations in conserved residues and characterized one cancer-associated mutation that significantly impairs protein function and autophagy activity. Extending the study, we determined a region around the mutant residue to be essential for protein function, which had yet to be examined in previous studies. In addition, we created a yeast system expressing the human ATG4B protein to study mutations in the residues that are not conserved from human to yeast. Using this yeast model, we identified six cancer-associated mutations affecting autophagy. The effects of these mutations were further tested in mammalian cells using a quadruple ATG4 gene knockout cell line. Our study proves the principle of using human disease-associated mutations to study Atg proteins in yeast and generates a yeast tool that is helpful for a rapid screen of mutations to determine the autophagy phenotype, providing a new perspective in studying autophagy and its relation with cancer.Abbreviations: 4KO: ATG4 tetra knockout; ATG: autophagy related; BafA1: bafilomycin A1; GFP: green fluorescent protein; LC3-II: PE-conjugated form of LC3B; ORF: open reading frame; PE: phosphatidylethanolamine; RFP: red fluorescent protein; SEP: superecliptic pHluorin; Ubl: ubiquitin-like; UCEC: uterine corpus endometrial carcinoma.
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Affiliation(s)
- Yuchen Lei
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Louise Uoselis
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | | | - Ying Yang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Michael Lazarou
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Daniel J Klionsky
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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2
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Fajtova P, Hurysz BM, Miyamoto Y, Serafim MSM, Jiang Z, Vazquez JM, Trujillo DF, Liu LJ, Somani U, Almaliti J, Myers SA, Caffrey CR, Gerwick WH, McMinn DL, Kirk CJ, Boura E, Eckmann L, O'Donoghue AJ. Distinct substrate specificities of the three catalytic subunits of the Trichomonas vaginalis proteasome. Protein Sci 2024; 33:e5225. [PMID: 39589076 PMCID: PMC11590128 DOI: 10.1002/pro.5225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Revised: 09/25/2024] [Accepted: 11/06/2024] [Indexed: 11/27/2024]
Abstract
The protozoan parasite Trichomonas vaginalis (Tv) causes trichomoniasis, the most common non-viral sexually transmitted infection in the world. Although Tv has been linked to significant health complications, only two closely related 5-nitroimidazole drugs are approved for its treatment. The emergence of resistance to these drugs and lack of alternative treatment options poses an increasing threat to public health, making development of novel anti-Trichomonas compounds an urgent need. The proteasome, a critical enzyme complex found in all eukaryotes has three catalytic subunits, β1, β2, and β5 and has been validated as a drug target to treat trichomoniasis. With the goal of developing tools to study the Tv proteasome, we isolated the enzyme complex and identified inhibitors that preferentially inactivate either one or two of the three catalytic subunits. Using a mass spectrometry-based peptide digestion assay, these inhibitors were used to define the substrate preferences of the β1, β2 and β5 subunits. Subsequently, three model fluorogenic substrates were designed, each specific for one of the catalytic subunits. This novel substrate profiling methodology will allow for individual subunit characterization of other proteasomes of interest. Using the new substrates, we screened a library of 284 peptide epoxyketone inhibitors against Tv and determined the subunits targeted by the most active compounds. The data show that inhibition of the Tv β5 subunit alone is toxic to the parasite. Taken together, the optimized proteasome subunit substrates will be instrumental for understanding the molecular determinants of proteasome specificity and for accelerating drug development against trichomoniasis.
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Affiliation(s)
- Pavla Fajtova
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of SciencesPrague 6Czech Republic
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
| | - Brianna M. Hurysz
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
| | - Yukiko Miyamoto
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
- Department of MedicineUniversity of California San DiegoLa JollaCaliforniaUSA
| | - Mateus Sá M. Serafim
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
- Departamento de Microbiologia, Instituto de Ciências BiológicasUniversidade Federal de Minas Gerais (UFMG)Belo HorizonteMinas GeraisBrazil
| | - Zhenze Jiang
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
| | - Julia M. Vazquez
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
| | - Diego F. Trujillo
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
| | - Lawrence J. Liu
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
| | - Urvashi Somani
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
| | - Jehad Almaliti
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCaliforniaUSA
| | - Samuel A. Myers
- Division of Signaling and Gene ExpressionLa Jolla Institute for ImmunologyLa JollaCaliforniaUSA
| | - Conor R. Caffrey
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
| | - William H. Gerwick
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
- Scripps Institution of OceanographyUniversity of California San DiegoLa JollaCaliforniaUSA
| | | | | | - Evzen Boura
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of SciencesPrague 6Czech Republic
| | - Lars Eckmann
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
- Department of MedicineUniversity of California San DiegoLa JollaCaliforniaUSA
| | - Anthony J. O'Donoghue
- Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoLa JollaCaliforniaUSA
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical SciencesUniversity of CaliforniaLa JollaCaliforniaUSA
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3
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Calvo Santos L, den Brave F. Analysis of quality control pathways for the translocase of the outer mitochondrial membrane. Methods Enzymol 2024; 707:565-584. [PMID: 39488391 DOI: 10.1016/bs.mie.2024.07.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2024]
Abstract
The functionality of mitochondria depends on the import of proteins synthesized on cytosolic ribosomes. Impaired import into mitochondria results in mitochondrial dysfunction and proteotoxic accumulation of precursor proteins in the cytosol. All proteins sorted to inner mitochondrial compartments are imported via the translocase of the outer membrane (TOM) complex. Premature protein folding, a reduction of the mitochondrial membrane potential or defects in translocases can result in precursor arrest during translocation, thereby clogging the TOM channel and blocking protein import. In recent years, different pathways have been identified, which employ the cytosolic ubiquitin-proteasome system in the extraction and turnover of precursor proteins from the TOM complex. Central events in this process are the modification of arrested precursor proteins with ubiquitin, their extraction by AAA-ATPases and subsequent degradation by the 26 S proteasome. Analysis of these processes is largely facilitated by the expression of model proteins that function as efficient "cloggers" of the import machinery. Here we describe the use of such clogger proteins and how their handling by the protein quality control machinery can be monitored. We provide protocols to study the extent of clogging, the ubiquitin-modification of arrested precursor proteins and their turnover by the 26 S proteasome.
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Affiliation(s)
- Lara Calvo Santos
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany
| | - Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, Bonn, Germany.
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4
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Johnson DL, Kumar R, Kakhniashvili D, Pfeffer LM, Laribee RN. Ccr4-not ubiquitin ligase signaling regulates ribosomal protein homeostasis and inhibits 40S ribosomal autophagy. J Biol Chem 2024; 300:107582. [PMID: 39025453 PMCID: PMC11357857 DOI: 10.1016/j.jbc.2024.107582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 06/27/2024] [Accepted: 07/10/2024] [Indexed: 07/20/2024] Open
Abstract
The Ccr4-Not complex contains the poorly understood Not4 ubiquitin ligase that functions in transcription, mRNA decay, translation, proteostasis, and endolysosomal nutrient signaling. To gain further insight into the in vivo functions of the ligase, we performed quantitative proteomics in Saccharomyces cerevisiae using yeast cells lacking Not4, or cells overexpressing wild-type Not4 or an inactive Not4 mutant. Herein, we provide evidence that balanced Not4 activity maintains ribosomal protein (RP) homeostasis independent of changes to RP mRNA or known Not4 ribosomal substrates. Intriguingly, we also find that Not4 loss activates 40S ribosomal autophagy independently of canonical Atg7-dependent macroautophagy, indicating that microautophagy is responsible. We previously demonstrated that Ccr4-Not stimulates the target of rapamycin complex 1 (TORC1) signaling, which activates RP expression and inhibits autophagy, by maintaining vacuole V-ATPase H+ pump activity. Importantly, combining Not4 deficient cells with a mutant that blocks vacuole H+ export fully restores RP expression and increases 40S RP autophagy efficiency. In contrast, restoring TORC1 activity alone fails to rescue either process, indicating that Not4 loss disrupts additional endolysosomal functions that regulate RP expression and 40S autophagy. Analysis of the Not4-regulated proteome reveals increases in endolysosomal and autophagy-related factors that functionally interact with Not4 to control RP expression and affect 40S autophagy. Collectively, our data indicate that balanced Ccr4-Not ubiquitin ligase signaling maintains RP homeostasis and inhibits 40S autophagy via the ligase's emerging role as an endolysosomal regulator.
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Affiliation(s)
- Daniel L Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Ravinder Kumar
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - David Kakhniashvili
- Proteomics and Metabolomics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Lawrence M Pfeffer
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - R Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
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5
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Chen PK, Chang YJ, Chou YW, Chen MY. Dysfunction of Avo3, an essential component of target of rapamycin complex 2, induces ubiquitin-proteasome-dependent downregulation of Avo2 in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2024; 717:150045. [PMID: 38718572 DOI: 10.1016/j.bbrc.2024.150045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Revised: 04/24/2024] [Accepted: 05/01/2024] [Indexed: 05/21/2024]
Abstract
The ubiquitin-proteasome system (UPS) plays a key role in maintaining cellular protein homeostasis and participates in modulating various cellular functions. Target of rapamycin (TOR), a highly conserved Ser/Thr kinase found across species from yeasts to humans, forms two multi-protein complexes, TORC1 and TORC2, to orchestrate cellular processes crucial for optimal growth, survival, and stress responses. While UPS-mediated regulation of mammalian TOR complexes has been documented, the ubiquitination of yeast TOR complexes remains largely unexplored. Here we report a functional interplay between the UPS and TORC2 in Saccharomyces cerevisiae. Using avo3-2ts, a temperature-sensitive mutant of the essential TORC2 component Avo3 exhibiting TORC2 defects at restrictive temperatures, we obtained evidence for UPS-dependent protein degradation and downregulation of the TORC2 component Avo2. Our results established the involvement of the E3 ubiquitin ligase Ubr1 and its catalytic activity in mediating Avo2 degradation in cells with defective Avo3. Coimmunoprecipitation revealed the interaction between Avo2 and Ubr1, indicating Avo2 as a potential substrate of Ubr1. Furthermore, depleting Ubr1 rescued the growth of avo3-2ts cells at restrictive temperatures, suggesting an essential role of Avo2 in sustaining cell viability under heat stress and/or TORC2 dysfunction. This study uncovers a role of UPS in yeast TORC2 regulation, highlighting the impact of protein degradation control on cellular signaling.
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Affiliation(s)
- Pao-Kuang Chen
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, 112304, Taiwan
| | - Yu-Jung Chang
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, 112304, Taiwan
| | - Yu-Wen Chou
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, 112304, Taiwan
| | - Mei-Yu Chen
- Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei, 112304, Taiwan; Faculty of Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei, 112304, Taiwan; Cancer and Immunology Research Center, National Yang Ming Chiao Tung University, Taipei, 112304, Taiwan.
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6
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Goncalves D, Duy DL, Peffer S, Morano KA. Cytoplasmic redox imbalance in the thioredoxin system activates Hsf1 and results in hyperaccumulation of the sequestrase Hsp42 with misfolded proteins. Mol Biol Cell 2024; 35:ar53. [PMID: 38381577 PMCID: PMC11064659 DOI: 10.1091/mbc.e23-07-0296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 02/09/2024] [Accepted: 02/16/2024] [Indexed: 02/23/2024] Open
Abstract
Cells employ multiple systems to maintain homeostasis when experiencing environmental stress. For example, the folding of nascent polypeptides is exquisitely sensitive to proteotoxic stressors including heat, pH, and oxidative stress, and is safeguarded by a network of protein chaperones that concentrate potentially toxic misfolded proteins into transient assemblies to promote folding or degradation. The redox environment itself is buffered by both cytosolic and organellar thioredoxin and glutathione pathways. How these systems are linked is poorly understood. Here, we determine that specific disruption of the cytosolic thioredoxin system resulted in constitutive activation of the heat shock response in Saccharomyces cerevisiae and accumulation of the sequestrase Hsp42 into an exaggerated and persistent juxtanuclear quality control (JUNQ) compartment. Terminally misfolded proteins also accumulated in this compartment in thioredoxin reductase (TRR1)-deficient cells, despite apparently normal formation and dissolution of transient cytoplasmic quality control (CytoQ) bodies during heat shock. Notably, cells lacking TRR1 and HSP42 exhibited severe synthetic slow growth exacerbated by oxidative stress, signifying a critical role for Hsp42 under redox-challenged conditions. Finally, we demonstrated that Hsp42 localization patterns in trr1∆ cells mimic those observed in chronically aging and glucose-starved cells, linking nutrient depletion and redox imbalance with management of misfolded proteins via a process of long-term sequestration.
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Affiliation(s)
- Davi Goncalves
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, Houston, TX 77030
| | - Duong Long Duy
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, Houston, TX 77030
| | - Sara Peffer
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, Houston, TX 77030
- Microbiology and Infectious Disease Program, MD Anderson UTHealth Graduate School at UTHealth Houston, Houston, TX 77030
| | - Kevin A. Morano
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, Houston, TX 77030
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7
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Renz C, Asimaki E, Meister C, Albanèse V, Petriukov K, Krapoth NC, Wegmann S, Wollscheid HP, Wong RP, Fulzele A, Chen JX, Léon S, Ulrich HD. Ubiquiton-An inducible, linkage-specific polyubiquitylation tool. Mol Cell 2024; 84:386-400.e11. [PMID: 38103558 PMCID: PMC10804999 DOI: 10.1016/j.molcel.2023.11.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 09/28/2023] [Accepted: 11/15/2023] [Indexed: 12/19/2023]
Abstract
The posttranslational modifier ubiquitin regulates most cellular processes. Its ability to form polymeric chains of distinct linkages is key to its diverse functionality. Yet, we still lack the experimental tools to induce linkage-specific polyubiquitylation of a protein of interest in cells. Here, we introduce a set of engineered ubiquitin protein ligases and matching ubiquitin acceptor tags for the rapid, inducible linear (M1-), K48-, or K63-linked polyubiquitylation of proteins in yeast and mammalian cells. By applying the so-called "Ubiquiton" system to proteasomal targeting and the endocytic pathway, we validate this tool for soluble cytoplasmic and nuclear as well as chromatin-associated and integral membrane proteins and demonstrate how it can be used to control the localization and stability of its targets. We expect that the Ubiquiton system will serve as a versatile, broadly applicable research tool to explore the signaling functions of polyubiquitin chains in many biological contexts.
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Affiliation(s)
- Christian Renz
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Evrydiki Asimaki
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Cindy Meister
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | | | - Kirill Petriukov
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Nils C Krapoth
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Sabrina Wegmann
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | | | - Ronald P Wong
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Amitkumar Fulzele
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Jia-Xuan Chen
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany
| | - Sébastien Léon
- Université de Paris, CNRS, Institut Jacques Monod, 75013 Paris, France
| | - Helle D Ulrich
- Institute of Molecular Biology (IMB) gGmbH, Ackermannweg 4, 55128 Mainz, Germany.
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8
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Johnson DL, Kumar R, Kakhniashvili D, Pfeffer LM, Laribee RN. Ccr4-Not ubiquitin ligase signaling regulates ribosomal protein homeostasis and inhibits 40S ribosomal autophagy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.28.555095. [PMID: 37693548 PMCID: PMC10491097 DOI: 10.1101/2023.08.28.555095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The Ccr4-Not complex containing the Not4 ubiquitin ligase regulates gene transcription and mRNA decay, yet it also has poorly defined roles in translation, proteostasis, and endolysosomal-dependent nutrient signaling. To define how Ccr4-Not mediated ubiquitin signaling regulates these additional processes, we performed quantitative proteomics in the yeast Saccharomyces cerevisiae lacking the Not4 ubiquitin ligase, and also in cells overexpressing either wild-type or functionally inactive ligase. Herein, we provide evidence that both increased and decreased Ccr4-Not ubiquitin signaling disrupts ribosomal protein (RP) homeostasis independently of reduced RP mRNA changes or reductions in known Not4 ribosomal substrates. Surprisingly, we also find that both Not4-mediated ubiquitin signaling, and the Ccr4 subunit, actively inhibit 40S ribosomal autophagy. This 40S autophagy is independent of canonical Atg7-dependent macroautophagy, thus indicating microautophagy activation is responsible. Furthermore, the Not4 ligase genetically interacts with endolysosomal pathway effectors to control both RP expression and 40S autophagy efficiency. Overall, we demonstrate that balanced Ccr4-Not ligase activity maintains RP homeostasis, and that Ccr4-Not ubiquitin signaling interacts with the endolysosomal pathway to both regulate RP expression and inhibit 40S ribosomal autophagy.
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Affiliation(s)
- Daniel L. Johnson
- Molecular Bioinformatics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - Ravinder Kumar
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - David Kakhniashvili
- Proteomics and Metabolomics Core and the University of Tennessee Health Science Center Office of Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - Lawrence M. Pfeffer
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
| | - R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and the Center for Cancer Research, University of Tennessee Health Science Center, Memphis, TN, United States of America
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9
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Gonçalves D, Peffer S, Morano KA. Cytoplasmic redox imbalance in the thioredoxin system activates Hsf1 and results in hyperaccumulation of the sequestrase Hsp42 with misfolded proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.26.546610. [PMID: 37425817 PMCID: PMC10327208 DOI: 10.1101/2023.06.26.546610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Cells employ multiple systems to maintain homeostasis when experiencing environmental stress. For example, the folding of nascent polypeptides is exquisitely sensitive to proteotoxic stressors including heat, pH and oxidative stress, and is safeguarded by a network of protein chaperones that concentrate potentially toxic misfolded proteins into transient assemblies to promote folding or degradation. The redox environment itself is buffered by both cytosolic and organellar thioredoxin and glutathione pathways. How these systems are linked is poorly understood. Here, we determine that specific disruption of the cytosolic thioredoxin system resulted in constitutive activation of the heat shock response in Saccharomyces cerevisiae and accumulation of the sequestrase Hsp42 into an exaggerated and persistent juxtanuclear quality control (JUNQ) compartment. Terminally misfolded proteins also accumulated in this compartment in thioredoxin reductase (TRR1)-deficient cells, despite apparently normal formation and dissolution of transient cytoplasmic quality control (CytoQ) bodies during heat shock. Notably, cells lacking TRR1 and HSP42 exhibited severe synthetic slow growth exacerbated by oxidative stress, signifying a critical role for Hsp42 under redox-challenged conditions. Finally, we demonstrated that Hsp42 localization patterns in trr1∆ cells mimic those observed in chronically aging and glucose-starved cells, linking nutrient depletion and redox imbalance with management of misfolded proteins via a mechanism of long-term sequestration.
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Affiliation(s)
- Davi Gonçalves
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, Houston, TX USA
- Current address: Cemvita Factory, Houston, TX USA
| | - Sara Peffer
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, Houston, TX USA
- MD Anderson UTHealth Graduate School at UTHealth Houston, Houston, TX USA
- Current address: Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX USA
| | - Kevin A. Morano
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth Houston, Houston, TX USA
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10
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Shetty S, Hofstetter J, Battaglioni S, Ritz D, Hall MN. TORC1 phosphorylates and inhibits the ribosome preservation factor Stm1 to activate dormant ribosomes. EMBO J 2023; 42:e112344. [PMID: 36691768 PMCID: PMC9975950 DOI: 10.15252/embj.2022112344] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 12/23/2022] [Accepted: 12/23/2022] [Indexed: 01/25/2023] Open
Abstract
Target of rapamycin complex 1 (TORC1) promotes biogenesis and inhibits the degradation of ribosomes in response to nutrient availability. To ensure a basal supply of ribosomes, cells are known to preserve a small pool of dormant ribosomes under nutrient-limited conditions. However, the regulation of these dormant ribosomes is poorly characterized. Here, we show that upon inhibition of yeast TORC1 by rapamycin or nitrogen starvation, the ribosome preservation factor Stm1 mediates the formation of nontranslating, dormant 80S ribosomes. Furthermore, Stm1-bound 80S ribosomes are protected from proteasomal degradation. Upon nutrient replenishment, TORC1 directly phosphorylates and inhibits Stm1 to reactivate translation. Finally, we find that SERBP1, a mammalian ortholog of Stm1, is likewise required for the formation of dormant 80S ribosomes upon mTORC1 inhibition in mammalian cells. These data suggest that TORC1 regulates ribosomal dormancy in an evolutionarily conserved manner by directly targeting a ribosome preservation factor.
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Affiliation(s)
| | | | | | - Danilo Ritz
- BiozentrumUniversity of BaselBaselSwitzerland
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11
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Zhang Y, Karmon O, Das K, Wiener R, Lehming N, Pines O. Ubiquitination Occurs in the Mitochondrial Matrix by Eclipsed Targeted Components of the Ubiquitination Machinery. Cells 2022; 11:cells11244109. [PMID: 36552873 PMCID: PMC9777009 DOI: 10.3390/cells11244109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022] Open
Abstract
Ubiquitination is a critical type of post-translational modification in eukaryotic cells. It is involved in regulating nearly all cellular processes in the cytosol and nucleus. Mitochondria, known as the metabolism heart of the cell, are organelles that evolved from bacteria. Using the subcellular compartment-dependent α-complementation, we detect multiple components of ubiquitination machinery as being eclipsed distributed to yeast mitochondria. Ubiquitin conjugates and mono-ubiquitin can be detected in lysates of isolated mitochondria from cells expressing HA-Ub and treated with trypsin. By expressing MTS (mitochondrial targeting sequence) targeted HA-tagged ubiquitin, we demonstrate that certain ubiquitination events specifically occur in yeast mitochondria and are independent of proteasome activity. Importantly, we show that the E2 Rad6 affects the pattern of protein ubiquitination in mitochondria and provides an in vivo assay for its activity in the matrix of the organelle. This study shows that ubiquitination occurs in the mitochondrial matrix by eclipsed targeted components of the ubiquitin machinery, providing a new perspective on mitochondrial and ubiquitination research.
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Affiliation(s)
- Yu Zhang
- NUS-HUJ-CREATE Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 138602, Singapore
| | - Ofri Karmon
- NUS-HUJ-CREATE Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 138602, Singapore
| | - Koyeli Das
- Department of Molecular Genetics and Microbiology, IMRIC, Faculty of Medicine, Hebrew University, Jerusalem 9112001, Israel
| | - Reuven Wiener
- Department of Biochemistry and Molecular Biology, IMRIC, Faculty of Medicine, Hebrew University, Jerusalem 9112001, Israel
| | - Norbert Lehming
- NUS-HUJ-CREATE Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 138602, Singapore
| | - Ophry Pines
- NUS-HUJ-CREATE Programme and Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 138602, Singapore
- Department of Molecular Genetics and Microbiology, IMRIC, Faculty of Medicine, Hebrew University, Jerusalem 9112001, Israel
- Correspondence:
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12
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Shukla PK, Sinha D, Leng AM, Bissell JE, Thatipamula S, Ganguly R, Radmall KS, Skalicky JJ, Shrieve DC, Chandrasekharan MB. Mutations of Rad6 E2 ubiquitin-conjugating enzymes at alanine-126 affect ubiquitination activity and decrease enzyme stability. J Biol Chem 2022; 298:102524. [PMID: 36162503 PMCID: PMC9630792 DOI: 10.1016/j.jbc.2022.102524] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 09/16/2022] [Accepted: 09/17/2022] [Indexed: 11/28/2022] Open
Abstract
Rad6, an E2 ubiquitin-conjugating enzyme conserved from yeast to humans, functions in transcription, genome maintenance, and proteostasis. The contributions of many conserved secondary structures of Rad6 and its human homologs UBE2A and UBE2B to their biological functions are not understood. A mutant RAD6 allele with a missense substitution at alanine-126 (A126) of helix-3 that causes defects in telomeric gene silencing, DNA repair, and protein degradation was reported over 2 decades ago. Here, using a combination of genetics, biochemical, biophysical, and computational approaches, we discovered that helix-3 A126 mutations compromise the ability of Rad6 to ubiquitinate target proteins without disrupting interactions with partner E3 ubiquitin-ligases that are required for their various biological functions in vivo. Explaining the defective in vitro or in vivo ubiquitination activities, molecular dynamics simulations and NMR showed that helix-3 A126 mutations cause local disorder of the catalytic pocket of Rad6 in addition to disorganizing the global structure of the protein to decrease its stability in vivo. We also show that helix-3 A126 mutations deform the structures of UBE2A and UBE2B, the human Rad6 homologs, and compromise the in vitro ubiquitination activity and folding of UBE2B. Providing insights into their ubiquitination defects, we determined helix-3 A126 mutations impair the initial ubiquitin charging and the final discharging steps during substrate ubiquitination by Rad6. In summary, our studies reveal that the conserved helix-3 is a crucial structural constituent that controls the organization of catalytic pockets, enzymatic activities, and biological functions of the Rad6-family E2 ubiquitin-conjugating enzymes.
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Affiliation(s)
- Prakash K Shukla
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dhiraj Sinha
- IHU, Aix Marseille University, Marseille, France
| | - Andrew M Leng
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jesse E Bissell
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Shravya Thatipamula
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Rajarshi Ganguly
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Kaitlin S Radmall
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Jack J Skalicky
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Dennis C Shrieve
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Mahesh B Chandrasekharan
- Department of Radiation Oncology and Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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13
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Bowman RW, Jordahl EM, Davis S, Hedayati S, Barsouk H, Ozbaki-Yagan N, Chiang A, Li Y, O’Donnell AF. TORC1 Signaling Controls the Stability and Function of α-Arrestins Aly1 and Aly2. Biomolecules 2022; 12:biom12040533. [PMID: 35454122 PMCID: PMC9031309 DOI: 10.3390/biom12040533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 03/22/2022] [Accepted: 03/25/2022] [Indexed: 02/06/2023] Open
Abstract
Nutrient supply dictates cell signaling changes, which in turn regulate membrane protein trafficking. To better exploit nutrients, cells relocalize membrane transporters via selective protein trafficking. Key in this reshuffling are the α-arrestins, selective protein trafficking adaptors conserved from yeast to man. α-Arrestins bind membrane proteins, controlling the ubiquitination and endocytosis of many transporters. To prevent the spurious removal of membrane proteins, α-arrestin-mediated endocytosis is kept in check through phospho-inhibition. This phospho-regulation is complex, with up to 87 phospho-sites on a single α-arrestin and many kinases/phosphatases targeting α-arrestins. To better define the signaling pathways controlling paralogous α-arrestins, Aly1 and Aly2, we screened the kinase and phosphatase deletion (KinDel) library, which is an array of all non-essential kinase and phosphatase yeast deletion strains, for modifiers of Aly-mediated phenotypes. We identified many Aly regulators, but focused our studies on the TORC1 kinase, a master regulator of nutrient signaling across eukaryotes. We found that TORC1 and its signaling effectors, the Sit4 protein phosphatase and Npr1 kinase, regulate the phosphorylation and stability of Alys. When Sit4 is lost, Alys are hyperphosphorylated and destabilized in an Npr1-dependent manner. These findings add new dimensions to our understanding of TORC1 regulation of α-arrestins and have important ramifications for cellular metabolism.
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Affiliation(s)
- Ray W. Bowman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.W.B.II); (E.M.J.); (S.D.); (S.H.); (H.B.); (N.O.-Y.); (A.C.)
| | - Eric M. Jordahl
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.W.B.II); (E.M.J.); (S.D.); (S.H.); (H.B.); (N.O.-Y.); (A.C.)
| | - Sydnie Davis
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.W.B.II); (E.M.J.); (S.D.); (S.H.); (H.B.); (N.O.-Y.); (A.C.)
| | - Stefanie Hedayati
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.W.B.II); (E.M.J.); (S.D.); (S.H.); (H.B.); (N.O.-Y.); (A.C.)
| | - Hannah Barsouk
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.W.B.II); (E.M.J.); (S.D.); (S.H.); (H.B.); (N.O.-Y.); (A.C.)
| | - Nejla Ozbaki-Yagan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.W.B.II); (E.M.J.); (S.D.); (S.H.); (H.B.); (N.O.-Y.); (A.C.)
| | - Annette Chiang
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.W.B.II); (E.M.J.); (S.D.); (S.H.); (H.B.); (N.O.-Y.); (A.C.)
| | - Yang Li
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA;
| | - Allyson F. O’Donnell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA; (R.W.B.II); (E.M.J.); (S.D.); (S.H.); (H.B.); (N.O.-Y.); (A.C.)
- Correspondence: ; Tel.: +1-412-648-4270
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14
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Li J, Hochstrasser M. Selective microautophagy of proteasomes is initiated by ESCRT-0 and is promoted by proteasome ubiquitylation. J Cell Sci 2022; 135:274460. [PMID: 35099016 PMCID: PMC8919337 DOI: 10.1242/jcs.259393] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 01/20/2022] [Indexed: 01/18/2023] Open
Abstract
The proteasome is central to proteolysis by the ubiquitin-proteasome system under normal growth conditions but is itself degraded through macroautophagy under nutrient stress. A recently described AMP-activated protein kinase (AMPK)-regulated endosomal sorting complex required for transport (ESCRT)-dependent microautophagy pathway also regulates proteasome trafficking and degradation in low-glucose conditions in yeast. Aberrant proteasomes are more prone to microautophagy, suggesting the ESCRT system fine-tunes proteasome quality control under low-glucose stress. Here, we uncover additional features of the selective microautophagy of proteasomes in budding yeast. Genetic or pharmacological induction of aberrant proteasomes is associated with increased mono- or oligo-ubiquitylation of proteasome components, which appears to be recognized by ESCRT-0. AMPK controls this pathway in part by regulating the trafficking of ESCRT-0 to the vacuole surface, which also leads to degradation of the Vps27 subunit of ESCRT-0. The Rsp5 ubiquitin ligase contributes to proteasome subunit ubiquitylation, and multiple ubiquitin-binding elements in Vps27 are involved in their recognition. We propose that ESCRT-0 at the vacuole surface recognizes ubiquitylated proteasomes and initiates their microautophagic elimination during glucose depletion. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Jianhui Li
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Mark Hochstrasser
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA,Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA,Author for correspondence ()
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15
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Buntenbroich I, Simões T, Escobar-Henriques M. Analysis of Protein Stability by Synthesis Shutoff. Bio Protoc 2021; 11:e4225. [PMID: 34909446 DOI: 10.21769/bioprotoc.4225] [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: 07/19/2018] [Revised: 10/02/2018] [Accepted: 10/18/2018] [Indexed: 11/02/2022] Open
Abstract
In this protocol, we describe the analysis of protein stability over time, using synthesis shutoff. As an example, we express HA-tagged yeast mitofusin Fzo1 in Saccharomyces cerevisiae and inhibit translation via cycloheximide (CHX). Proteasomal inhibition with MG132 is performed, as an optional step, before the addition of CHX. Proteins are extracted via trichloroacetic acid (TCA) precipitation and subsequently separated via SDS-PAGE. Immunoblotting and antibody-decoration are performed to detect Fzo1 using HA-specific antibodies. We have adapted the method of blocking protein translation with cycloheximide to analyze the stability of high molecular weight proteins, including post-translational modifications and their impact on protein turnover.
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Affiliation(s)
- Ira Buntenbroich
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Tânia Simões
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Mafalda Escobar-Henriques
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
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16
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de Lannoy C, Lucas FLR, Maglia G, de Ridder D. In silico assessment of a novel single-molecule protein fingerprinting method employing fragmentation and nanopore detection. iScience 2021; 24:103202. [PMID: 34703997 PMCID: PMC8521182 DOI: 10.1016/j.isci.2021.103202] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 08/10/2021] [Accepted: 09/28/2021] [Indexed: 10/28/2022] Open
Abstract
The identification of proteins at the single-molecule level would open exciting new venues in biological research and disease diagnostics. Previously, we proposed a nanopore-based method for protein identification called chop-n-drop fingerprinting, in which the fragmentation pattern induced and measured by a proteasome-nanopore construct is used to identify single proteins. In the simulation study presented here, we show that 97.1% of human proteome constituents are uniquely identified under close to ideal measuring circumstances, using a simple alignment-based classification method. We show that our method is robust against experimental error, as 69.4% can still be identified if the resolution is twice as low as currently attainable, and 10% of proteasome restriction sites and protein fragments are randomly ignored. Based on these results and our experimental proof of concept, we argue that chop-n-drop fingerprinting has the potential to make cost-effective single-molecule protein identification feasible in the near future.
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Affiliation(s)
- Carlos de Lannoy
- Bioinformatics Group, Wageningen University, 6708PB Wageningen, The Netherlands
| | | | - Giovanni Maglia
- Groningen Biomolecular Sciences & Biotechnology Institute, University of Groningen, 9747AG Groningen, The Netherlands
| | - Dick de Ridder
- Bioinformatics Group, Wageningen University, 6708PB Wageningen, The Netherlands
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17
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Panagaki D, Croft JT, Keuenhof K, Larsson Berglund L, Andersson S, Kohler V, Büttner S, Tamás MJ, Nyström T, Neutze R, Höög JL. Nuclear envelope budding is a response to cellular stress. Proc Natl Acad Sci U S A 2021; 118:e2020997118. [PMID: 34290138 PMCID: PMC8325156 DOI: 10.1073/pnas.2020997118] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Nuclear envelope budding (NEB) is a recently discovered alternative pathway for nucleocytoplasmic communication distinct from the movement of material through the nuclear pore complex. Through quantitative electron microscopy and tomography, we demonstrate how NEB is evolutionarily conserved from early protists to human cells. In the yeast Saccharomyces cerevisiae, NEB events occur with higher frequency during heat shock, upon exposure to arsenite or hydrogen peroxide, and when the proteasome is inhibited. Yeast cells treated with azetidine-2-carboxylic acid, a proline analog that induces protein misfolding, display the most dramatic increase in NEB, suggesting a causal link to protein quality control. This link was further supported by both localization of ubiquitin and Hsp104 to protein aggregates and NEB events, and the evolution of these structures during heat shock. We hypothesize that NEB is part of normal cellular physiology in a vast range of species and that in S. cerevisiae NEB comprises a stress response aiding the transport of protein aggregates across the nuclear envelope.
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Affiliation(s)
- Dimitra Panagaki
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Jacob T Croft
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Katharina Keuenhof
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Lisa Larsson Berglund
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Stefanie Andersson
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Verena Kohler
- Department of Molecular Bioscienses, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
| | - Sabrina Büttner
- Department of Molecular Bioscienses, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
| | - Markus J Tamás
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Thomas Nyström
- Department of Microbiology and Immunology, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Richard Neutze
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Johanna L Höög
- Department of Chemistry and Molecular Biology, University of Gothenburg, 405 30 Gothenburg, Sweden;
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18
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López-Berges MS, Scheven MT, Hortschansky P, Misslinger M, Baldin C, Gsaller F, Werner ER, Krüger T, Kniemeyer O, Weber J, Brakhage AA, Haas H. The bZIP Transcription Factor HapX Is Post-Translationally Regulated to Control Iron Homeostasis in Aspergillus fumigatus. Int J Mol Sci 2021; 22:ijms22147739. [PMID: 34299357 PMCID: PMC8307855 DOI: 10.3390/ijms22147739] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 07/15/2021] [Indexed: 11/21/2022] Open
Abstract
The airborne fungus Aspergillus fumigatus causes opportunistic infections in humans with high mortality rates in immunocompromised patients. Previous work established that the bZIP transcription factor HapX is essential for virulence via adaptation to iron limitation by repressing iron-consuming pathways and activating iron acquisition mechanisms. Moreover, HapX was shown to be essential for transcriptional activation of vacuolar iron storage and iron-dependent pathways in response to iron availability. Here, we demonstrate that HapX has a very short half-life during iron starvation, which is further decreased in response to iron, while siderophore biosynthetic enzymes are very stable. We identified Fbx22 and SumO as HapX interactors and, in agreement, HapX post-translational modifications including ubiquitination of lysine161, sumoylation of lysine242 and phosphorylation of threonine319. All three modifications were enriched in the immediate adaptation from iron-limiting to iron-replete conditions. Interfering with these post-translational modifications, either by point mutations or by inactivation, of Fbx22 or SumO, altered HapX degradation, heme biosynthesis and iron resistance to different extents. Consistent with the need to precisely regulate HapX protein levels, overexpression of hapX caused significant growth defects under iron sufficiency. Taken together, our results indicate that post-translational regulation of HapX is important to control iron homeostasis in A. fumigatus.
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Affiliation(s)
- Manuel Sánchez López-Berges
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
- Correspondence: (M.S.L.-B.); (A.A.B.); (H.H.)
| | - Mareike Thea Scheven
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Peter Hortschansky
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
| | - Matthias Misslinger
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
| | - Clara Baldin
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
| | - Fabio Gsaller
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
| | - Ernst R. Werner
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, 6020 Innsbruck, Austria;
| | - Thomas Krüger
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
| | - Olaf Kniemeyer
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
| | - Jakob Weber
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
| | - Axel A. Brakhage
- Department of Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology (Leibniz-HKI), 07745 Jena, Germany; (M.T.S.); (P.H.); (T.K.); (O.K.); (J.W.)
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany
- Correspondence: (M.S.L.-B.); (A.A.B.); (H.H.)
| | - Hubertus Haas
- Institute of Molecular Biology, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria; (M.M.); (C.B.); (F.G.)
- Correspondence: (M.S.L.-B.); (A.A.B.); (H.H.)
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19
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Pinkerton M, Ruetenik A, Bazylianska V, Nyvltova E, Barrientos A. Salvage NAD+ biosynthetic pathway enzymes moonlight as molecular chaperones to protect against proteotoxicity. Hum Mol Genet 2021; 30:672-686. [PMID: 33749726 DOI: 10.1093/hmg/ddab080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/03/2021] [Accepted: 03/15/2021] [Indexed: 11/13/2022] Open
Abstract
Human neurodegenerative proteinopathies are disorders associated with abnormal protein depositions in brain neurons. They include polyglutamine (polyQ) conditions such as Huntington's disease (HD) and α-synucleinopathies such as Parkinson's disease (PD). Overexpression of NMNAT/Nma1, an enzyme in the NAD+ biosynthetic salvage pathway, acts as an efficient suppressor of proteotoxicities in yeast, fly and mouse models. Screens in yeast models of HD and PD allowed us to identify three additional enzymes of the same pathway that achieve similar protection against proteotoxic stress: Npt1, Pnc1 and Qns1. The mechanism by which these proteins maintain proteostasis has not been identified. Here, we report that their ability to maintain proteostasis in yeast models of HD and PD is independent of their catalytic activity and does not require cellular protein quality control systems such as the proteasome or autophagy. Furthermore, we show that, under proteotoxic stress, the four proteins are recruited as molecular chaperones with holdase and foldase activities. The NAD+ salvage proteins act by preventing misfolding and, together with the Hsp90 chaperone, promoting the refolding of extended polyQ domains and α-synuclein (α-Syn). Our results illustrate the existence of an evolutionarily conserved strategy of repurposing or moonlighting housekeeping enzymes under stress conditions to maintain proteostasis. We conclude that the entire salvage NAD+ biosynthetic pathway links NAD+ metabolism and proteostasis and emerges as a target for therapeutics to combat age-associated neurodegenerative proteotoxicities.
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Affiliation(s)
- Meredith Pinkerton
- Department of Neurology and Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Andrea Ruetenik
- Department of Neurology and Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Viktoriia Bazylianska
- Department of Neurology and Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,MS in Biochemistry and Molecular Biology, Wayne State University, School of Medicine. Detroit, MI 48201, USA
| | - Eva Nyvltova
- Department of Neurology and Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Antoni Barrientos
- Department of Neurology and Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.,Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine. Miami, FL 33136, USA
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20
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Walvekar AS, Kadamur G, Sreedharan S, Gupta R, Srinivasan R, Laxman S. Methylated PP2A stabilizes Gcn4 to enable a methionine-induced anabolic program. J Biol Chem 2020; 295:18390-18405. [PMID: 33122193 PMCID: PMC7939465 DOI: 10.1074/jbc.ra120.014248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 10/25/2020] [Indexed: 11/06/2022] Open
Abstract
Methionine, through S-adenosylmethionine, activates a multifaceted growth program in which ribosome biogenesis, carbon metabolism, and amino acid and nucleotide biosynthesis are induced. This growth program requires the activity of the Gcn4 transcription factor (called ATF4 in mammals), which facilitates the supply of metabolic precursors that are essential for anabolism. However, how Gcn4 itself is regulated in the presence of methionine is unknown. Here, we discover that Gcn4 protein levels are increased by methionine, despite conditions of high cell growth and translation (in which the roles of Gcn4 are not well-studied). We demonstrate that this mechanism of Gcn4 induction is independent of transcription, as well as the conventional Gcn2/eIF2α-mediated increased translation of Gcn4. Instead, when methionine is abundant, Gcn4 phosphorylation is decreased, which reduces its ubiquitination and therefore degradation. Gcn4 is dephosphorylated by the protein phosphatase 2A (PP2A); our data show that when methionine is abundant, the conserved methyltransferase Ppm1 methylates and alters the activity of the catalytic subunit of PP2A, shifting the balance of Gcn4 toward a dephosphorylated, stable state. The absence of Ppm1 or the loss of the PP2A methylation destabilizes Gcn4 even when methionine is abundant, leading to collapse of the Gcn4-dependent anabolic program. These findings reveal a novel, methionine-dependent signaling and regulatory axis. Here methionine directs the conserved methyltransferase Ppm1 via its target phosphatase PP2A to selectively stabilize Gcn4. Through this, cells conditionally modify a major phosphatase to stabilize a metabolic master regulator and drive anabolism.
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Affiliation(s)
- Adhish S Walvekar
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India
| | - Ganesh Kadamur
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India
| | - Sreesa Sreedharan
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India; School of Chemical and Biotechnology, SASTRA University, Tanjavur, India
| | - Ritu Gupta
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India
| | | | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine (inStem), Bangalore, India.
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21
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Perrino G, Wilson C, Santorelli M, di Bernardo D. Quantitative Characterization of α-Synuclein Aggregation in Living Cells through Automated Microfluidics Feedback Control. Cell Rep 2020; 27:916-927.e5. [PMID: 30995486 PMCID: PMC6484782 DOI: 10.1016/j.celrep.2019.03.081] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 02/20/2019] [Accepted: 03/22/2019] [Indexed: 12/21/2022] Open
Abstract
Aggregation of α-synuclein and formation of inclusions are hallmarks of Parkinson’s disease (PD). Aggregate formation is affected by cellular environment, but it has been studied almost exclusively in cell-free systems. We quantitatively analyzed α-synuclein inclusion formation and clearance in a yeast cell model of PD expressing either wild-type (WT) α-synuclein or the disease-associated A53T mutant from the galactose (Gal)-inducible promoter. A computer-controlled microfluidics device regulated α-synuclein in cells by means of closed-loop feedback control. We demonstrated that inclusion formation is strictly concentration dependent and that the aggregation threshold of the A53T mutant is about half of the WT α-synuclein (56%). We chemically modulated the proteasomal and autophagic pathways and demonstrated that autophagy is the main determinant of A53T α-synuclein inclusions’ clearance. In addition to proposing a technology to overcome current limitations in dynamically regulating protein expression levels, our results contribute to the biology of PD and have relevance for therapeutic applications. In silico feedback control enables regulation of α-synuclein expression in yeast α-Synuclein inclusion formation is strictly concentration, but not time, dependent The aggregation threshold of the α-synuclein A53T mutant is 56% of the wild-type Autophagy induction speeds up inclusion clearance in the A53T α-synuclein strain
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Affiliation(s)
- Giansimone Perrino
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Cathal Wilson
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Marco Santorelli
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Diego di Bernardo
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy; Department of Chemical, Materials and Industrial Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, 80125 Naples, Italy.
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22
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Caloric restriction rescues yeast cells from alpha-synuclein toxicity through autophagic control of proteostasis. Aging (Albany NY) 2019; 10:3821-3833. [PMID: 30530923 PMCID: PMC6326672 DOI: 10.18632/aging.101675] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 11/18/2018] [Indexed: 01/31/2023]
Abstract
α-Synuclein (SNCA) is a presynaptic protein that is associated with the pathophysiology of synucleinopathies, including Parkinson's disease. SNCA is a naturally aggregation-prone protein, which may be degraded by the ubiquitin-proteasome system (UPS) and by lysosomal degradation pathways. Besides being a target of the proteolytic systems, SNCA can also alter the function of these pathways further, contributing to the progression of neurodegeneration. Deterioration of UPS and autophagy activities with aging further aggravates this toxic cycle. Caloric restriction (CR) is still the most effective non-genetic intervention promoting lifespan extension. It is known that CR-mediated lifespan extension is linked to the regulation of proteolytic systems, but the mechanisms underlying CR rescue of SNCA toxicity remain poorly understood. This study shows that CR balances UPS and autophagy activities during aging. CR enhances UPS activity, reversing the decline of the UPS activity promoted by SNCA, and keeps autophagy at homeostatic levels. Maintenance of autophagy at homeostatic levels appears to be relevant for UPS activity and for the mechanism underlying rescue of cells from SNCA-mediated toxicity by CR.
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23
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Tufegdzic Vidakovic A, Harreman M, Dirac-Svejstrup AB, Boeing S, Roy A, Encheva V, Neumann M, Wilson M, Snijders AP, Svejstrup JQ. Analysis of RNA polymerase II ubiquitylation and proteasomal degradation. Methods 2019; 159-160:146-156. [PMID: 30769100 PMCID: PMC6617506 DOI: 10.1016/j.ymeth.2019.02.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 12/19/2022] Open
Abstract
Transcribing RNA polymerase II (RNAPII) is decorated by a plethora of post-translational modifications that mark different stages of transcription. One important modification is RNAPII ubiquitylation, which occurs in response to numerous different stimuli that cause RNAPII stalling, such as DNA damaging agents, RNAPII inhibitors, or depletion of the nucleotide pool. Stalled RNAPII triggers a so-called "last resort pathway", which involves RNAPII poly-ubiquitylation and proteasome-mediated degradation. Different approaches have been described to study RNAPII poly-ubiquitylation and degradation, each method with its own advantages and caveats. Here, we describe optimised strategies for detecting ubiquitylated RNAPII and studying its degradation, but these protocols are suitable for studying other ubiquitylated proteins as well.
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Affiliation(s)
- Ana Tufegdzic Vidakovic
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michelle Harreman
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - A Barbara Dirac-Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Stefan Boeing
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Anindya Roy
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Vesela Encheva
- Protein Analysis and Proteomics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michelle Neumann
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Marcus Wilson
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Ambrosius P Snijders
- Protein Analysis and Proteomics Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
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24
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Liu L, Levin DE. Intracellular mechanism by which genotoxic stress activates yeast SAPK Mpk1. Mol Biol Cell 2018; 29:2898-2909. [PMID: 30230955 PMCID: PMC6249863 DOI: 10.1091/mbc.e18-07-0441] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Stress-activated MAP kinases (SAPKs) respond to a wide variety of stressors. In most cases, the pathways through which specific stress signals are transmitted to the SAPKs are not known. The Saccharomyces cerevisiae SAPK Mpk1 (Slt2) is a well-characterized component of the cell-wall integrity (CWI) signaling pathway, which responds to physical and chemical challenges to the cell wall. However, Mpk1 is also activated in response to genotoxic stress through an unknown pathway. We show that, in contrast to cell-wall stress, the pathway for Mpk1 activation by genotoxic stress does not involve the stimulation of the MAP kinase kinases (MEKs) that function immediately upstream of Mpk1. Instead, DNA damage activates Mpk1 through induction of proteasomal degradation of Msg5, the dual-specificity protein phosphatase principally responsible for maintaining Mpk1 in a low-activity state in the absence of stress. Blocking Msg5 degradation in response to genotoxic stress prevented Mpk1 activation. This work raises the possibility that other Mpk1-activating stressors act intracellularly at different points along the canonical Mpk1 activation pathway.
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Affiliation(s)
- Li Liu
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, MA 02118
| | - David E Levin
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, MA 02118.,Department of Microbiology, Boston University School of Medicine, Boston, MA 02118
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25
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Phosphorylation and Proteasome Recognition of the mRNA-Binding Protein Cth2 Facilitates Yeast Adaptation to Iron Deficiency. mBio 2018; 9:mBio.01694-18. [PMID: 30228242 PMCID: PMC6143738 DOI: 10.1128/mbio.01694-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Iron is a vital element for many metabolic pathways, including the synthesis of DNA and proteins, and the generation of energy via oxidative phosphorylation. Therefore, living organisms have developed tightly controlled mechanisms to properly distribute iron, since imbalances lead to nutritional deficiencies, multiple diseases, and vulnerability against pathogens. Saccharomyces cerevisiae Cth2 is a conserved mRNA-binding protein that coordinates a global reprogramming of iron metabolism in response to iron deficiency in order to optimize its utilization. Here we report that the phosphorylation of Cth2 at specific serine residues is essential to regulate the stability of the protein and adaptation to iron depletion. We identify the kinase and ubiquitination machinery implicated in this process to establish a posttranscriptional regulatory model. These results and recent findings for both mammals and plants reinforce the privileged position of E3 ubiquitin ligases and phosphorylation events in the regulation of eukaryotic iron homeostasis. Iron is an indispensable micronutrient for all eukaryotic organisms due to its participation as a redox cofactor in many metabolic pathways. Iron imbalance leads to the most frequent human nutritional deficiency in the world. Adaptation to iron limitation requires a global reorganization of the cellular metabolism directed to prioritize iron utilization for essential processes. In response to iron scarcity, the conserved Saccharomyces cerevisiae mRNA-binding protein Cth2, which belongs to the tristetraprolin family of tandem zinc finger proteins, coordinates a global remodeling of the cellular metabolism by promoting the degradation of multiple mRNAs encoding highly iron-consuming proteins. In this work, we identify a critical mechanism for the degradation of Cth2 protein during the adaptation to iron deficiency. Phosphorylation of a patch of Cth2 serine residues within its amino-terminal region facilitates recognition by the SCFGrr1 ubiquitin ligase complex, accelerating Cth2 turnover by the proteasome. When Cth2 degradation is impaired by either mutagenesis of the Cth2 serine residues or deletion of GRR1, the levels of Cth2 rise and abrogate growth in iron-depleted conditions. Finally, we uncover that the casein kinase Hrr25 phosphorylates and promotes Cth2 destabilization. These results reveal a sophisticated posttranslational regulatory pathway necessary for the adaptation to iron depletion.
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26
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Spear ED, Hsu ET, Nie L, Carpenter EP, Hrycyna CA, Michaelis S. ZMPSTE24 missense mutations that cause progeroid diseases decrease prelamin A cleavage activity and/or protein stability. Dis Model Mech 2018; 11:dmm.033670. [PMID: 29794150 PMCID: PMC6078402 DOI: 10.1242/dmm.033670] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 05/16/2018] [Indexed: 12/24/2022] Open
Abstract
The human zinc metalloprotease ZMPSTE24 is an integral membrane protein crucial for the final step in the biogenesis of the nuclear scaffold protein lamin A, encoded by LMNA. After farnesylation and carboxyl methylation of its C-terminal CAAX motif, the lamin A precursor (prelamin A) undergoes proteolytic removal of its modified C-terminal 15 amino acids by ZMPSTE24. Mutations in LMNA or ZMPSTE24 that impede this prelamin A cleavage step cause the premature aging disease Hutchinson-Gilford progeria syndrome (HGPS), and the related progeroid disorders mandibuloacral dysplasia type B (MAD-B) and restrictive dermopathy (RD). Here, we report the development of a ‘humanized yeast system’ to assay ZMPSTE24-dependent cleavage of prelamin A and examine the eight known disease-associated ZMPSTE24 missense mutations. All mutations show diminished prelamin A processing and fall into three classes, with defects in activity, protein stability or both. Notably, some ZMPSTE24 mutants can be rescued by deleting the E3 ubiquitin ligase Doa10, involved in endoplasmic reticulum (ER)-associated degradation of misfolded membrane proteins, or by treatment with the proteasome inhibitor bortezomib. This finding may have important therapeutic implications for some patients. We also show that ZMPSTE24-mediated prelamin A cleavage can be uncoupled from the recently discovered role of ZMPSTE24 in clearance of ER membrane translocon-clogged substrates. Together with the crystal structure of ZMPSTE24, this humanized yeast system can guide structure-function studies to uncover mechanisms of prelamin A cleavage, translocon unclogging, and membrane protein folding and stability. Summary: The zinc metalloprotease ZMPSTE24 performs the final step of prelamin A processing. Here, a yeast-based system shows differences in protein stability and activity for alleles of ZMPSTE24 that cause progeria disease.
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Affiliation(s)
- Eric D Spear
- Department of Cell Biology, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Erh-Ting Hsu
- Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Laiyin Nie
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK
| | | | | | - Susan Michaelis
- Department of Cell Biology, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
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27
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Gopalakrishnan S, Ediga HH, Reddy SS, Reddy GB, Ismail A. Procyanidin-B2 enriched fraction of cinnamon acts as a proteasome inhibitor and anti-proliferative agent in human prostate cancer cells. IUBMB Life 2018. [DOI: 10.1002/iub.1735] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Srividya Gopalakrishnan
- Department of Endocrinology and Metabolism; National Institute of Nutrition; Hyderabad Telangana India
| | | | - S. Sreenivasa Reddy
- Department of Biochemistry; National Institute of Nutrition; Hyderabad Telangana India
| | - G. Bhanuprakash Reddy
- Department of Biochemistry; National Institute of Nutrition; Hyderabad Telangana India
| | - Ayesha Ismail
- Department of Endocrinology and Metabolism; National Institute of Nutrition; Hyderabad Telangana India
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28
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Cold atmospheric pressure plasma causes protein denaturation and endoplasmic reticulum stress in Saccharomyces cerevisiae. Appl Microbiol Biotechnol 2018; 102:2279-2288. [PMID: 29356871 DOI: 10.1007/s00253-018-8758-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/11/2017] [Accepted: 12/17/2017] [Indexed: 12/14/2022]
Abstract
Cold atmospheric pressure plasma (CAP) does not cause thermal damage or generate toxic residues; hence, it is projected as an alternative agent for sterilization in food and pharmaceutical industries. The fungicidal effects of CAP have not yet been investigated as extensively as its bactericidal effects. We herein examined the effects of CAP on yeast proteins using a new CAP system with an improved processing capacity. We demonstrated that protein ubiquitination and the formation of protein aggregates were induced in the cytoplasm of yeast cells by the CAP treatment. GFP-tagged Tsa1 and Ssa1, an H2O2-responsive molecular chaperone and constitutively expressed Hsp70, respectively, formed cytoplasmic foci in CAP-treated cells. Furthermore, Tsa1 was essential for the formation of Ssa1-GFP foci. These results indicate that the denaturation of yeast proteins was caused by CAP, at least partially, in a H2O2-dependent manner. Furthermore, misfolded protein levels in the endoplasmic reticulum (ER) and the oligomerization of Ire1, a key sensor of ER stress, were enhanced by the treatment with CAP, indicating that CAP causes ER stress in yeast cells as a specific phenomenon to eukaryotic cells. The pretreatment of yeast cells at 37 °C significantly alleviated cell death caused by CAP. Our results strongly suggest that the induction of protein denaturation is a primary mechanism of the fungicidal effects of CAP.
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29
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Avagliano Trezza R, van den Burg J, van den Oever N, Distel B. A versatile plasmid system for reconstitution and analysis of mammalian ubiquitination cascades in yeast. ACTA ACUST UNITED AC 2017; 5:150-157. [PMID: 29487861 PMCID: PMC5826702 DOI: 10.15698/mic2018.03.620] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Ubiquitination is a posttranslational protein modification that regulates most aspects of cellular life. The sheer number of ubiquitination enzymes that are present in a mammalian cell, over 700 in total, has thus far hampered the analysis of distinct protein ubiquitination cascades in a cellular context. To overcome this complexity we have developed a versatile vector system that allows the reconstitution of specific ubiquitination cascades in the model eukaryote Saccharomyces cerevisae (baker’s yeast). The vector system consists of 32 modular yeast shuttle plasmids allowing inducible or constitutive expression of up to four proteins of interest in a single cell. To demonstrate the validity of the system, we show that co-expression in yeast of the mammalian HECT type E3 ubiquitin ligase E6AP (E6-Associated Protein) and a model substrate faithfully recapitulates E6AP-dependent substrate ubiquitination and degradation. In addition, we show that the endogenous sumoylation pathway of S. cerevisiae can specifically sumoylate mouse PML (Promyelocytic leukemia protein). In conclusion, the yeast vector system described in this paper provides a versatile tool to study complex post-translational modifications in a cellular setting.
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Affiliation(s)
- Rossella Avagliano Trezza
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Janny van den Burg
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Nico van den Oever
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Ben Distel
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.,Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
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30
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Nemec AA, Howell LA, Peterson AK, Murray MA, Tomko RJ. Autophagic clearance of proteasomes in yeast requires the conserved sorting nexin Snx4. J Biol Chem 2017; 292:21466-21480. [PMID: 29109144 DOI: 10.1074/jbc.m117.817999] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/03/2017] [Indexed: 11/06/2022] Open
Abstract
Turnover of the 26S proteasome by autophagy is an evolutionarily conserved process that governs cellular proteolytic capacity and eliminates inactive particles. In most organisms, proteasomes are located in both the nucleus and cytoplasm. However, the specific autophagy routes for nuclear and cytoplasmic proteasomes are unclear. Here, we investigate the spatial control of autophagic proteasome turnover in budding yeast (Saccharomyces cerevisiae). We found that nitrogen starvation-induced proteasome autophagy is independent of known nucleophagy pathways but is compromised when nuclear protein export is blocked. Furthermore, via pharmacological tethering of proteasomes to chromatin or the plasma membrane, we provide evidence that nuclear proteasomes at least partially disassemble before autophagic turnover, whereas cytoplasmic proteasomes remain largely intact. A targeted screen of autophagy genes identified a requirement for the conserved sorting nexin Snx4 in the autophagic turnover of proteasomes and several other large multisubunit complexes. We demonstrate that Snx4 cooperates with sorting nexins Snx41 and Snx42 to mediate proteasome turnover and is required for the formation of cytoplasmic proteasome puncta that accumulate when autophagosome formation is blocked. Together, our results support distinct mechanistic paths in the turnover of nuclear versus cytoplasmic proteasomes and point to a critical role for Snx4 in cytoplasmic agglomeration of proteasomes en route to autophagic destruction.
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Affiliation(s)
- Antonia A Nemec
- From the Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306
| | - Lauren A Howell
- From the Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306
| | - Anna K Peterson
- From the Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306
| | - Matthew A Murray
- From the Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306
| | - Robert J Tomko
- From the Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306
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31
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Lauinger L, Li J, Shostak A, Cemel IA, Ha N, Zhang Y, Merkl PE, Obermeyer S, Stankovic-Valentin N, Schafmeier T, Wever WJ, Bowers AA, Carter KP, Palmer AE, Tschochner H, Melchior F, Deshaies RJ, Brunner M, Diernfellner A. Thiolutin is a zinc chelator that inhibits the Rpn11 and other JAMM metalloproteases. Nat Chem Biol 2017; 13:709-714. [PMID: 28459440 DOI: 10.1038/nchembio.2370] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/22/2017] [Indexed: 12/21/2022]
Abstract
Thiolutin is a disulfide-containing antibiotic and anti-angiogenic compound produced by Streptomyces. Its biological targets are not known. We show that reduced thiolutin is a zinc chelator that inhibits the JAB1/MPN/Mov34 (JAMM) domain-containing metalloprotease Rpn11, a deubiquitinating enzyme of the 19S proteasome. Thiolutin also inhibits the JAMM metalloproteases Csn5, the deneddylase of the COP9 signalosome; AMSH, which regulates ubiquitin-dependent sorting of cell-surface receptors; and BRCC36, a K63-specific deubiquitinase of the BRCC36-containing isopeptidase complex and the BRCA1-BRCA2-containing complex. We provide evidence that other dithiolopyrrolones also function as inhibitors of JAMM metalloproteases.
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Affiliation(s)
- Linda Lauinger
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Jing Li
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Anton Shostak
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | | | - Nati Ha
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Yaru Zhang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Philipp E Merkl
- Lehrstuhl Biochemie III, Biochemie Zentrum Regensburg, Universität Regensburg, Regensburg, Germany
| | - Simon Obermeyer
- Lehrstuhl Biochemie III, Biochemie Zentrum Regensburg, Universität Regensburg, Regensburg, Germany
| | - Nicolas Stankovic-Valentin
- Zentrum Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Heidelberg University, Heidelberg, Germany
| | | | - Walter J Wever
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Albert A Bowers
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Kyle P Carter
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, USA
| | - Amy E Palmer
- Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado, USA
| | - Herbert Tschochner
- Lehrstuhl Biochemie III, Biochemie Zentrum Regensburg, Universität Regensburg, Regensburg, Germany
| | - Frauke Melchior
- Zentrum Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Heidelberg University, Heidelberg, Germany
| | - Raymond J Deshaies
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California, USA
| | - Michael Brunner
- Heidelberg University Biochemistry Center, Heidelberg, Germany
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32
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Ruan L, Zhou C, Jin E, Kucharavy A, Zhang Y, Wen Z, Florens L, Li R. Cytosolic proteostasis through importing of misfolded proteins into mitochondria. Nature 2017; 543:443-446. [PMID: 28241148 PMCID: PMC5793917 DOI: 10.1038/nature21695] [Citation(s) in RCA: 341] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Accepted: 02/09/2017] [Indexed: 12/31/2022]
Abstract
Loss of proteostasis underlies aging and neurodegeneration characterized by the accumulation of protein aggregates and mitochondrial dysfunction1–5. Although many neurodegenerative-disease proteins can be found in mitochondria4,6, it remains unclear how these disease manifestations may be related. In yeast, protein aggregates formed under stress or during aging are preferentially retained by the mother cell in part through tethering to mitochondria, while the disaggregase Hsp104 helps dissociate aggregates to enable refolding or degradation of misfolded proteins7–10. Here we show that in yeast cytosolic proteins prone to aggregation are imported into mitochondria for degradation. Protein aggregates formed under heat shock (HS) contain both cytosolic and mitochondrial proteins and interact with mitochondrial import complex. Many aggregation-prone proteins enter mitochondrial intermembrane space and matrix after HS, while some do so even without stress. Timely dissolution of cytosolic aggregates requires mitochondrial import machinery and proteases. Blocking mitochondrial import but not the proteasome activity causes a marked delay in the degradation of aggregated proteins. Defects in cytosolic Hsp70s leads to enhanced entry of misfolded proteins into mitochondria and elevated mitochondrial stress. We term this mitochondria-mediated proteostasis mechanism MAGIC (mitochondria as guardian in cytosol) and provide evidence that it may exist in human cells.
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Affiliation(s)
- Linhao Ruan
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, Baltimore, Maryland 21205, USA.,Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Chuankai Zhou
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, Missouri 64110, USA
| | - Erli Jin
- Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Andrei Kucharavy
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, Baltimore, Maryland 21205, USA.,Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Ying Zhang
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, Missouri 64110, USA
| | - Zhihui Wen
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, Missouri 64110, USA
| | - Laurence Florens
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, Missouri 64110, USA
| | - Rong Li
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University School of Medicine, 855 North Wolfe Street, Baltimore, Maryland 21205, USA.,Department of Chemical and Biomolecular Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
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33
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Ahuja JS, Sandhu R, Mainpal R, Lawson C, Henley H, Hunt PA, Yanowitz JL, Börner GV. Control of meiotic pairing and recombination by chromosomally tethered 26S proteasome. Science 2017; 355:408-411. [PMID: 28059715 DOI: 10.1126/science.aaf4778] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 09/12/2016] [Accepted: 12/05/2016] [Indexed: 12/11/2022]
Abstract
During meiosis, paired homologous chromosomes (homologs) become linked via the synaptonemal complex (SC) and crossovers. Crossovers mediate homolog segregation and arise from self-inflicted double-strand breaks (DSBs). Here, we identified a role for the proteasome, the multisubunit protease that degrades proteins in the nucleus and cytoplasm, in homolog juxtaposition and crossing over. Without proteasome function, homologs failed to pair and instead remained associated with nonhomologous chromosomes. Although dispensable for noncrossover formation, a functional proteasome was required for a coordinated transition that entails SC assembly between longitudinally organized chromosome axes and stable strand exchange of crossover-designated DSBs. Notably, proteolytic core and regulatory proteasome particles were recruited to chromosomes by Zip3, the ortholog of mammalian E3 ligase RNF212, and SC protein Zip1 . We conclude that proteasome functions along meiotic chromosomes are evolutionarily conserved.
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Affiliation(s)
- Jasvinder S Ahuja
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University (CSU), Cleveland, OH, USA
| | - Rima Sandhu
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University (CSU), Cleveland, OH, USA
| | - Rana Mainpal
- Magee-Womens Research Institute, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Crystal Lawson
- School of Molecular Biosciences, Center for Reproductive Biology, Washington State University, Pullman, WA, USA
| | - Hanna Henley
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University (CSU), Cleveland, OH, USA
| | - Patricia A Hunt
- School of Molecular Biosciences, Center for Reproductive Biology, Washington State University, Pullman, WA, USA
| | - Judith L Yanowitz
- Magee-Womens Research Institute, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - G Valentin Börner
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University (CSU), Cleveland, OH, USA. .,Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, USA.,Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
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Yu H, Singh Gautam AK, Wilmington SR, Wylie D, Martinez-Fonts K, Kago G, Warburton M, Chavali S, Inobe T, Finkelstein IJ, Babu MM, Matouschek A. Conserved Sequence Preferences Contribute to Substrate Recognition by the Proteasome. J Biol Chem 2016; 291:14526-39. [PMID: 27226608 PMCID: PMC4938175 DOI: 10.1074/jbc.m116.727578] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Indexed: 11/23/2022] Open
Abstract
The proteasome has pronounced preferences for the amino acid sequence of its substrates at the site where it initiates degradation. Here, we report that modulating these sequences can tune the steady-state abundance of proteins over 2 orders of magnitude in cells. This is the same dynamic range as seen for inducing ubiquitination through a classic N-end rule degron. The stability and abundance of His3 constructs dictated by the initiation site affect survival of yeast cells and show that variation in proteasomal initiation can affect fitness. The proteasome's sequence preferences are linked directly to the affinity of the initiation sites to their receptor on the proteasome and are conserved between Saccharomyces cerevisiae, Schizosaccharomyces pombe, and human cells. These findings establish that the sequence composition of unstructured initiation sites influences protein abundance in vivo in an evolutionarily conserved manner and can affect phenotype and fitness.
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Affiliation(s)
- Houqing Yu
- From the Department of Molecular Biosciences and the Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208
| | | | - Shameika R Wilmington
- From the Department of Molecular Biosciences and the Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208
| | - Dennis Wylie
- the Center for Computational Biology and Bioinformatics, The University of Texas at Austin, Austin, Texas 78712
| | - Kirby Martinez-Fonts
- From the Department of Molecular Biosciences and the Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208
| | - Grace Kago
- From the Department of Molecular Biosciences and
| | | | - Sreenivas Chavali
- the Medical Research Council, Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom, and
| | - Tomonao Inobe
- Frontier Research Core for Life Sciences, University of Toyama, 3190 Gofuku, Toyama-shi, Toyama 930-8555, Japan
| | | | - M Madan Babu
- the Medical Research Council, Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom, and
| | - Andreas Matouschek
- From the Department of Molecular Biosciences and the Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208,
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Abstract
Ubiquitylation is a reversible posttranslational modification that is critical for most, if not all, cellular processes and essential for viability. Ubiquitin conjugates to substrate proteins either as a single moiety (monoubiquitylation) or as polymers composed of ubiquitin molecules linked to each other with various topologies and structures (polyubiquitylation). This contributes to an elaborate ubiquitin code that is decrypted by specific ubiquitin-binding proteins. Indeed, these different types of ubiquitylation have different functional outcomes, notably affecting the stability of the substrate, its interactions, its activity, or its subcellular localization. In this chapter, we describe protocols to determine whether a protein is ubiquitylated, to identify the site that is ubiquitylated, and provide direction to study the topology of the ubiquitin modification, in the yeast Saccharomyces cerevisiae.
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Affiliation(s)
- Junie Hovsepian
- Institut Jacques Monod, UMR 7592 CNRS/Univ. Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Michel Becuwe
- Institut Jacques Monod, UMR 7592 CNRS/Univ. Paris Diderot, Sorbonne Paris Cité, Paris, France
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, MA, 02115, USA
| | - Oded Kleifeld
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - Michael H Glickman
- Department of Biology, Technion-Israel Institute of Technology, Haifa, Israel
| | - Sébastien Léon
- Institut Jacques Monod, UMR 7592 CNRS/Univ. Paris Diderot, Sorbonne Paris Cité, Paris, France.
- Membrane Trafficking, Ubiquitin and Signaling Lab, Institut Jacques Monod, UMR7592 CNRS/Université Paris-Diderot, 15 Rue Hélène Brion, Bât. Buffon, 75205, Paris Cedex 13, France.
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36
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Yao Y, Tsuchiyama S, Yang C, Bulteau AL, He C, Robison B, Tsuchiya M, Miller D, Briones V, Tar K, Potrero A, Friguet B, Kennedy BK, Schmidt M. Proteasomes, Sir2, and Hxk2 form an interconnected aging network that impinges on the AMPK/Snf1-regulated transcriptional repressor Mig1. PLoS Genet 2015; 11:e1004968. [PMID: 25629410 PMCID: PMC4309596 DOI: 10.1371/journal.pgen.1004968] [Citation(s) in RCA: 33] [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: 07/22/2014] [Accepted: 12/19/2014] [Indexed: 01/20/2023] Open
Abstract
Elevated proteasome activity extends lifespan in model organisms such as yeast, worms and flies. This pro-longevity effect might be mediated by improved protein homeostasis, as this protease is an integral module of the protein homeostasis network. Proteasomes also regulate cellular processes through temporal and spatial degradation of signaling pathway components. Here we demonstrate that the regulatory function of the proteasome plays an essential role in aging cells and that the beneficial impact of elevated proteasome capacity on lifespan partially originates from deregulation of the AMPK signaling pathway. Proteasome-mediated lifespan extension activity was carbon-source dependent and cells with enhancement proteasome function exhibited increased respiratory activity and oxidative stress response. These findings suggested that the pro-aging impact of proteasome upregulation might be related to changes in the metabolic state through a premature induction of respiration. Deletion of yeast AMPK, SNF1, or its activator SNF4 abrogated proteasome-mediated lifespan extension, supporting this hypothesis as the AMPK pathway regulates metabolism. We found that the premature induction of respiration in cells with increased proteasome activity originates from enhanced turnover of Mig1, an AMPK/Snf1 regulated transcriptional repressor that prevents the induction of genes required for respiration. Increasing proteasome activity also resulted in partial relocation of Mig1 from the nucleus to the mitochondria. Collectively, the results argue for a model in which elevated proteasome activity leads to the uncoupling of Snf1-mediated Mig1 regulation, resulting in a premature activation of respiration and thus the induction of a mitohormetic response, beneficial to lifespan. In addition, we observed incorrect Mig1 localization in two other long-lived yeast aging models: cells that overexpress SIR2 or deleted for the Mig1-regulator HXK2. Finally, compromised proteasome function blocks lifespan extension in both strains. Thus, our findings suggest that proteasomes, Sir2, Snf1 and Hxk2 form an interconnected aging network that controls metabolism through coordinated regulation of Mig1. Advanced cellular age is associated with decreased efficiency of the proteostasis network. The proteasome, a protease in the cytoplasm and nuclei of eukaryotic cells, is an important component of this network. Recent studies demonstrate that increased proteasome capacity has a positive impact on longevity. The underlying mechanisms, however, have not been fully identified. Here we report that proteasomes are involved in regulating the AMP-activated kinase (AMPK) pathway and thus participate in correct metabolic adaptation. We find that Mig1, a transcriptional repressor downstream of yeast AMPK, Snf1, is a proteasome target and a negative regulator of lifespan. Increased proteasome activity results in enhanced turnover and incorrect localization of Mig1. The reduced Mig1 levels result in the induction of respiration and upregulation of the oxidative stress response. Premature Mig1 inactivation is also observed in two additional long-lived strains that overexpress SIR2 or are deleted for HXK2 and lifespan extension in both strains requires correct proteasome function. Our results uncover an interconnected network comprised of the proteasome, Sir2 and AMPK/Hxk2 signaling that impacts longevity through regulation of Mig1 and modulates respiratory metabolism. Mechanistic information on the cross-communication between these pathways is expected to facilitate the identification of novel pro-aging interventions.
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Affiliation(s)
- Yanhua Yao
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | | | - Ciyu Yang
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | | | - Chong He
- Buck Institute, Novato, California, United States of America
| | - Brett Robison
- Buck Institute, Novato, California, United States of America
| | | | - Delana Miller
- Buck Institute, Novato, California, United States of America
| | - Valeria Briones
- Buck Institute, Novato, California, United States of America
| | - Krisztina Tar
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - Anahi Potrero
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
| | - Bertrand Friguet
- Laboratoire de Biologie Cellulaire du Vieillissement, UR4-IFR83, Université Pierre et Marie Curie-Paris 6, Paris, France
| | - Brian K. Kennedy
- Buck Institute, Novato, California, United States of America
- * E-mail: (MS); (BKK)
| | - Marion Schmidt
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, New York, United States of America
- * E-mail: (MS); (BKK)
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Lewicki MC, Srikumar T, Johnson E, Raught B. The S. cerevisiae SUMO stress response is a conjugation-deconjugation cycle that targets the transcription machinery. J Proteomics 2014; 118:39-48. [PMID: 25434491 DOI: 10.1016/j.jprot.2014.11.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 11/06/2014] [Accepted: 11/10/2014] [Indexed: 01/07/2023]
Abstract
UNLABELLED The small ubiquitin-related modifier (SUMO) "stress response" (SSR) is a poorly understood evolutionarily conserved phenomenon in which steady-state SUMO conjugate levels are dramatically increased in response to environmental stresses. Here we characterize Saccharomyces cerevisiae SSR kinetics in response to several different types of stress, demonstrate that SSR activation and inactivation do not require protein synthesis or proteasome-dependent degradation, and establish that the SSR is effected primarily by the Siz1 E3 ligase and inactivated by the SUMO-specific protease Ulp2. Affinity purification coupled with mass spectrometry identifies the primary hyperosmotic SSR targets as components of the TFIID and mediator complexes, Pol II-associated mRNA maturation factors, chromatin remodeling proteins, and the transcriptional co-repressor Tup1-Cyc8. Consistent with these findings, our data also suggest that ongoing transcription (but not translation) is required to activate the SSR. The SSR thus does not appear to be directly linked to the stress itself, but likely represents a synchronized wave of sumoylation that occurs as a consequence of the large-scale, coordinated changes in the transcriptional program in response to environmental stress. BIOLOGICAL SIGNIFICANCE SUMO is a ubiquitin-like protein with a number of important biological functions. Increased levels of sumoylation are associated with a number of human diseases, and previous reports have described an evolutionarily conserved "SUMO stress response" (SSR), in which SUMO conjugate levels are markedly increased in response to environmental stresses. However, the connection between cellular stress and sumoylation has remained poorly understood. Here we conduct the first in-depth characterization of the S. cerevisiae SSR. The SUMO system components required to effect it are identified, and SSR kinetics in response to different types of environmental stresses are established. Using mass spectrometry, we identify the principle osmotic shock-associated SSR targets as components of the basal transcription machinery, transcriptional regulators and chromatin remodeling complexes. Consistent with these data, we also observe that the sumoylation of SSR targets is dependent upon, and thus appears to be coupled with, transcription. Together, our data suggest that the SSR is not responsive to environmental stress per se, but more likely reflects a synchronized, transcription-coupled wave of sumoylation that accompanies the rapid, global re-programming of transcription in response to stress. This article is part of a Special Issue entitled: Protein dynamics in health and disease. Guest Editors: Pierre Thibault and Anne-Claude Gingras.
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Affiliation(s)
- Megan C Lewicki
- Princess Margaret Cancer Centre, University Health Network and Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Tharan Srikumar
- Princess Margaret Cancer Centre, University Health Network and Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Erica Johnson
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Brian Raught
- Princess Margaret Cancer Centre, University Health Network and Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.
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38
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Functions of the proteasome on chromatin. Biomolecules 2014; 4:1026-44. [PMID: 25422899 PMCID: PMC4279168 DOI: 10.3390/biom4041026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 09/11/2014] [Accepted: 11/10/2014] [Indexed: 12/11/2022] Open
Abstract
The proteasome is a large self-compartmentalized protease complex that recognizes, unfolds, and destroys ubiquitylated substrates. Proteasome activities are required for a host of cellular functions, and it has become clear in recent years that one set of critical actions of the proteasome occur on chromatin. In this review, we discuss some of the ways in which proteasomes directly regulate the structure and function of chromatin and chromatin regulatory proteins, and how this influences gene transcription. We discuss lingering controversies in the field, the relative importance of proteolytic versus non-proteolytic proteasome activities in this process, and highlight areas that require further investigation. Our intention is to show that proteasomes are involved in major steps controlling the expression of the genetic information, that proteasomes use both proteolytic mechanisms and ATP-dependent protein remodeling to accomplish this task, and that much is yet to be learned about the full spectrum of ways that proteasomes influence the genome.
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39
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Abstract
Ubiquitin is a small 8.5 kDa protein that is conjugated to a target protein in a concerted three step enzymatic process. Ubiquitin addition can drastically affect function or target the modified protein for degradation. Ubiquitin modifications have important regulatory roles in disease progression, such as in cancer and neurodegenerative diseases to name a few. As a consequence, it is imperative to identify important ubiquitin targets to elucidate the role of the modification. Proteomic studies have sought to understand this role by identifying proteome-wide ubiquitylated proteins. Two central ideas have developed to characterize the ubiquitylome: affinity purification of ubiquitylated proteins and optimization of GG-peptide enrichment. In this review, we will discuss recent advances in both approaches and discuss how these studies are essential to pharmacoproteomics.
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Affiliation(s)
- Tanya R Porras-Yakushi
- California Institute of Technology, Beckman Institute, 1200 E. California Blvd, Pasadena, CA 91125, USA
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40
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Tenreiro S, Reimão-Pinto MM, Antas P, Rino J, Wawrzycka D, Macedo D, Rosado-Ramos R, Amen T, Waiss M, Magalhães F, Gomes A, Santos CN, Kaganovich D, Outeiro TF. Phosphorylation modulates clearance of alpha-synuclein inclusions in a yeast model of Parkinson's disease. PLoS Genet 2014; 10:e1004302. [PMID: 24810576 PMCID: PMC4014446 DOI: 10.1371/journal.pgen.1004302] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 02/28/2014] [Indexed: 12/02/2022] Open
Abstract
Alpha-synuclein (aSyn) is the main component of proteinaceous inclusions known as Lewy bodies (LBs), the typical pathological hallmark of Parkinson's disease (PD) and other synucleinopathies. Although aSyn is phosphorylated at low levels under physiological conditions, it is estimated that ∼90% of aSyn in LBs is phosphorylated at S129 (pS129). Nevertheless, the significance of pS129 in the biology of aSyn and in PD pathogenesis is still controversial. Here, we harnessed the power of budding yeast in order to assess the implications of phosphorylation on aSyn cytotoxicity, aggregation and sub-cellular distribution. We found that aSyn is phosphorylated on S129 by endogenous kinases. Interestingly, phosphorylation reduced aSyn toxicity and the percentage of cells with cytosolic inclusions, in comparison to cells expressing mutant forms of aSyn (S129A or S129G) that mimic the unphosphorylated form of aSyn. Using high-resolution 4D imaging and fluorescence recovery after photobleaching (FRAP) in live cells, we compared the dynamics of WT and S129A mutant aSyn. While WT aSyn inclusions were very homogeneous, inclusions formed by S129A aSyn were larger and showed FRAP heterogeneity. Upon blockade of aSyn expression, cells were able to clear the inclusions formed by WT aSyn. However, this process was much slower for the inclusions formed by S129A aSyn. Interestingly, whereas the accumulation of WT aSyn led to a marked induction of autophagy, cells expressing the S129A mutant failed to activate this protein quality control pathway. The finding that the phosphorylation state of aSyn on S129 can alter the ability of cells to clear aSyn inclusions provides important insight into the role that this posttranslational modification may have in the pathogenesis of PD and other synucleinopathies, opening novel avenues for investigating the molecular basis of these disorders and for the development of therapeutic strategies. Protein aggregation is a common hallmark in neurodegenerative disorders, but is also associated with phenotypic plasticity in a variety of organisms, including yeasts. Alpha-synuclein (aSyn) forms aggregates that are typical of synucleinopathies, and is phosphorylated at S129, but the significance of phosphorylation in the biology and pathophysiology of the protein is still controversial. Exploring the power of budding yeast, we found phosphorylation reduced aSyn toxicity and inclusion formation. While inclusions formed by WT aSyn were homogeneous, those formed by S129A aSyn were larger and heterogeneous. Interestingly, clearance of aSyn inclusions was reduced in cells expressing S129A aSyn, correlating with deficient autophagy activation. The finding that phosphorylation alters the ability of cells to clear aSyn inclusions provides novel insight into the role phosphorylation may have in synucleinopathies, and suggests posttranslational modifications might constitute switches cells use to control the aggregation and clearance of key proteins, opening novel avenues for the development of therapeutic strategies for these devastating disorders.
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Affiliation(s)
- Sandra Tenreiro
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (ST); (TFO)
| | - Madalena M. Reimão-Pinto
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Pedro Antas
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - José Rino
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Donata Wawrzycka
- Department of Genetics and Cell Physiology, Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
| | - Diana Macedo
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Rita Rosado-Ramos
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Triana Amen
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Meytal Waiss
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Filipa Magalhães
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Andreia Gomes
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Cláudia N. Santos
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Daniel Kaganovich
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Tiago Fleming Outeiro
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- Instituto de Fisiologia, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- Department of NeuroDegeneration and Restorative Research, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
- * E-mail: (ST); (TFO)
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41
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Patananan AN, Capri J, Whitelegge JP, Clarke SG. Non-repair pathways for minimizing protein isoaspartyl damage in the yeast Saccharomyces cerevisiae. J Biol Chem 2014; 289:16936-53. [PMID: 24764295 DOI: 10.1074/jbc.m114.564385] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The spontaneous degradation of asparaginyl and aspartyl residues to isoaspartyl residues is a common type of protein damage in aging organisms. Although the protein-l-isoaspartyl (d-aspartyl) O-methyltransferase (EC 2.1.1.77) can initiate the repair of l-isoaspartyl residues to l-aspartyl residues in most organisms, no gene homolog or enzymatic activity is present in the budding yeast Saccharomyces cerevisiae. Therefore, we used biochemical approaches to elucidate how proteins containing isoaspartyl residues are metabolized in this organism. Surprisingly, the level of isoaspartyl residues in yeast proteins (50-300 pmol of isoaspartyl residues/mg of protein extract) is comparable with organisms with protein-l-isoaspartyl (d-aspartyl) O-methyltransferase, suggesting a novel regulatory pathway. Interfering with common protein quality control mechanisms by mutating and inhibiting the proteasomal and autophagic pathways in vivo did not increase isoaspartyl residue levels compared with wild type or uninhibited cells. However, the inhibition of metalloproteases in in vitro aging experiments by EDTA resulted in an ∼3-fold increase in the level of isoaspartyl-containing peptides. Characterization by mass spectrometry of these peptides identified several proteins involved in metabolism as targets of isoaspartyl damage. Further analysis of these peptides revealed that many have an N-terminal isoaspartyl site and originate from proteins with short half-lives. These results suggest that one or more metalloproteases participate in limiting isoaspartyl formation by robust proteolysis.
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Affiliation(s)
- Alexander N Patananan
- From the Department of Chemistry and Biochemistry and the Molecular Biology Institute and
| | - Joseph Capri
- the Pasarow Mass Spectrometry Laboratory, Neuropsychiatric Institute-Semel Institute for Neuroscience and Human Behavior, UCLA, Los Angeles, California 90095
| | - Julian P Whitelegge
- the Pasarow Mass Spectrometry Laboratory, Neuropsychiatric Institute-Semel Institute for Neuroscience and Human Behavior, UCLA, Los Angeles, California 90095
| | - Steven G Clarke
- From the Department of Chemistry and Biochemistry and the Molecular Biology Institute and
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42
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Wilson MD, Harreman M, Taschner M, Reid J, Walker J, Erdjument-Bromage H, Tempst P, Svejstrup JQ. Proteasome-mediated processing of Def1, a critical step in the cellular response to transcription stress. Cell 2013; 154:983-995. [PMID: 23993092 PMCID: PMC3778974 DOI: 10.1016/j.cell.2013.07.028] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 05/30/2013] [Accepted: 07/19/2013] [Indexed: 11/25/2022]
Abstract
DNA damage triggers polyubiquitylation and degradation of the largest subunit of RNA polymerase II (RNAPII), a "mechanism of last resort" employed during transcription stress. In yeast, this process is dependent on Def1 through a previously unresolved mechanism. Here, we report that Def1 becomes activated through ubiquitylation- and proteasome-dependent processing. Def1 processing results in the removal of a domain promoting cytoplasmic localization, resulting in nuclear accumulation of the clipped protein. Nuclear Def1 then binds RNAPII, utilizing a ubiquitin-binding domain to recruit the Elongin-Cullin E3 ligase complex via a ubiquitin-homology domain in the Ela1 protein. This facilitates polyubiquitylation of Rpb1, triggering its proteasome-mediated degradation. Together, these results outline the multistep mechanism of Rpb1 polyubiquitylation triggered by transcription stress and uncover the key role played by Def1 as a facilitator of Elongin-Cullin ubiquitin ligase function.
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Affiliation(s)
- Marcus D Wilson
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD, UK
| | - Michelle Harreman
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD, UK
| | - Michael Taschner
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD, UK
| | - James Reid
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD, UK
| | - Jane Walker
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD, UK
| | - Hediye Erdjument-Bromage
- Molecular Biology Programme, Memorial Sloan-Kettering Cancer Center, York Avenue 1275, New York, NY 10021, USA
| | - Paul Tempst
- Molecular Biology Programme, Memorial Sloan-Kettering Cancer Center, York Avenue 1275, New York, NY 10021, USA
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD, UK.
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43
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Reithinger JH, Kim JEH, Kim H. Sec62 protein mediates membrane insertion and orientation of moderately hydrophobic signal anchor proteins in the endoplasmic reticulum (ER). J Biol Chem 2013; 288:18058-67. [PMID: 23632075 DOI: 10.1074/jbc.m113.473009] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Nascent chains are known to be targeted to the endoplasmic reticulum membrane either by a signal recognition particle (SRP)-dependent co-translational or by an SRP-independent post-translational translocation route depending on signal sequences. Using a set of model and cellular proteins carrying an N-terminal signal anchor sequence of controlled hydrophobicity and yeast mutant strains defective in SRP or Sec62 function, the hydrophobicity-dependent targeting efficiency and targeting pathway preference were systematically evaluated. Our results suggest that an SRP-dependent co-translational and an SRP-independent post-translational translocation are not mutually exclusive for signal anchor proteins and that moderately hydrophobic ones require both SRP and Sec62 for proper targeting and translocation to the endoplasmic reticulum. Further, defect in Sec62 selectively reduced signal sequences inserted in an N(in)-C(out) (type II) membrane topology, implying an undiscovered role of Sec62 in regulating the orientation of the signal sequence in an early stage of translocation.
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Gulshan K, Thommandru B, Moye-Rowley WS. Proteolytic degradation of the Yap1 transcription factor is regulated by subcellular localization and the E3 ubiquitin ligase Not4. J Biol Chem 2012; 287:26796-805. [PMID: 22707721 DOI: 10.1074/jbc.m112.384719] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Saccharomyces cerevisiae Yap1 is a transcriptional regulatory protein that serves as a central determinant of oxidative stress tolerance. Activity of this factor is regulated in large part by control of its subcellular location. In the absence of oxidants, Yap1 is primarily located in the cytoplasm. Upon oxidant challenge, Yap1 accumulates rapidly in the nucleus where it activates expression of genes required for oxidative stress tolerance such as the thioredoxin TRX2. Here, we demonstrate that Yap1 degradation is accelerated in response to oxidative stress. Yap1 is folded differently depending on the oxidant used to induce its nuclear localization but is degraded similarly, irrespective of its folded status. Mutant forms of Yap1 that are constitutively trapped in the nucleus are degraded in the absence of an oxidant signal. Degradation requires the ability of the protein to bind DNA and a domain in the amino-terminal region of the factor. Inhibition of the proteasome prevents Yap1 turnover. Screening a variety of mutants involved in ubiquitin-mediated proteolysis demonstrated an important role for the nuclear ubiquitin ligase Not4 in Yap1 degradation. Not4 was found to bind to Yap1 in an oxidant-stimulated fashion. The Candida albicans Yap1 homologue (Cap1) also was degraded after oxidant challenge. These data uncover a new, conserved pathway for regulation of the oxidative stress response that serves to temporally limit the duration of Yap1-dependent transcriptional activation.
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Affiliation(s)
- Kailash Gulshan
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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Similar temporal and spatial recruitment of native 19S and 20S proteasome subunits to transcriptionally active chromatin. Proc Natl Acad Sci U S A 2012; 109:6060-5. [PMID: 22474342 DOI: 10.1073/pnas.1200854109] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
It has recently become clear that components of the proteasome are recruited to sites of gene transcription. Prevailing evidence suggests that the transcriptionally relevant form of the proteasome is a subcomplex of 19S base proteins, which functions as an ATP-dependent chaperone that influences transcriptional processes. Despite this notion, compelling evidence for a transcription-dedicated 19S base complex is lacking, and 20S proteasome subunits have been shown to associate with chromatin in some contexts. To gain insight into the form of the proteasome that is recruited to chromatin, we assembled a panel of highly specific antibodies that recognize native yeast proteasome subunits in chromatin immunoprecipitation assays. Using these reagents, we show that components from the three major subassemblies of the proteasome--19S lid, 19S base, and 20S core--associate with the activated GAL10 gene in yeast in a virtually indistinguishable manner. We find that proteasome subunits Rpt1, Rpt4, Rpn8, Rpn12, Pre6, and Pre10 are recruited to GAL10 rapidly upon galactose induction. These subunits associate with the entire transcribed portion of GAL10, display near-identical patterns of distribution, and dissociate from chromatin rapidly once transcription is shut down. We also find that proteasome subunits are enriched at telomeres and at genes transcribed by RNA polymerase III. Our data suggest that the transcriptionally relevant form of the proteasome is the canonical 26S complex.
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Abstract
Regulation of gene transcription is vitally important for the maintenance of normal cellular homeostasis. Failure to correctly regulate gene expression, or to deal with problems that arise during the transcription process, can lead to cellular catastrophe and disease. One of the ways cells cope with the challenges of transcription is by making extensive use of the proteolytic and nonproteolytic activities of the ubiquitin-proteasome system (UPS). Here, we review recent evidence showing deep mechanistic connections between the transcription and ubiquitin-proteasome systems. Our goal is to leave the reader with a sense that just about every step in transcription-from transcription initiation through to export of mRNA from the nucleus-is influenced by the UPS and that all major arms of the system--from the first step in ubiquitin (Ub) conjugation through to the proteasome-are recruited into transcriptional processes to provide regulation, directionality, and deconstructive power.
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Affiliation(s)
- Fuqiang Geng
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-8240, USA.
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Howard GC, Collins GA, Tansey WP. Letter to the editor. Chemical-genetic strategy for inhibiting proteasome function in Saccharomyces cerevisiae. Yeast 2011; 29:93-4. [PMID: 22162073 DOI: 10.1002/yea.1919] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Gregory C Howard
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
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Haarer B, Aggeli D, Viggiano S, Burke DJ, Amberg DC. Novel interactions between actin and the proteasome revealed by complex haploinsufficiency. PLoS Genet 2011; 7:e1002288. [PMID: 21966278 PMCID: PMC3178594 DOI: 10.1371/journal.pgen.1002288] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 07/29/2011] [Indexed: 11/18/2022] Open
Abstract
Saccharomyces cerevisiae has been a powerful model for uncovering the landscape of binary gene interactions through whole-genome screening. Complex heterozygous interactions are potentially important to human genetic disease as loss-of-function alleles are common in human genomes. We have been using complex haploinsufficiency (CHI) screening with the actin gene to identify genes related to actin function and as a model to determine the prevalence of CHI interactions in eukaryotic genomes. Previous CHI screening between actin and null alleles for non-essential genes uncovered ∼240 deleterious CHI interactions. In this report, we have extended CHI screening to null alleles for essential genes by mating a query strain to sporulations of heterozygous knock-out strains. Using an act1Δ query, knock-outs of 60 essential genes were found to be CHI with actin. Enriched in this collection were functional categories found in the previous screen against non-essential genes, including genes involved in cytoskeleton function and chaperone complexes that fold actin and tubulin. Novel to this screen was the identification of genes for components of the TFIID transcription complex and for the proteasome. We investigated a potential role for the proteasome in regulating the actin cytoskeleton and found that the proteasome physically associates with actin filaments in vitro and that some conditional mutations in proteasome genes have gross defects in actin organization. Whole-genome screening with actin as a query has confirmed that CHI interactions are important phenotypic drivers. Furthermore, CHI screening is another genetic tool to uncover novel functional connections. Here we report a previously unappreciated role for the proteasome in affecting actin organization and function.
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Affiliation(s)
- Brian Haarer
- Department of Biochemistry and Molecular Biology, Upstate Medical University, State University of New York, Syracuse, New York, United States of America
| | - Dimitra Aggeli
- Department of Biochemistry and Molecular Biology, Upstate Medical University, State University of New York, Syracuse, New York, United States of America
| | - Susan Viggiano
- Department of Biochemistry and Molecular Biology, Upstate Medical University, State University of New York, Syracuse, New York, United States of America
| | - Daniel J. Burke
- Department of Biochemistry and Molecular Genetics, University of Virginia Medical Center, Charlottesville, Virginia, United States of America
| | - David C. Amberg
- Department of Biochemistry and Molecular Biology, Upstate Medical University, State University of New York, Syracuse, New York, United States of America
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