1
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Ruger-Herreros C, Svoboda L, Mogk A, Bukau B. Role of J-domain Proteins in Yeast Physiology and Protein Quality Control. J Mol Biol 2024; 436:168484. [PMID: 38331212 DOI: 10.1016/j.jmb.2024.168484] [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: 10/20/2023] [Revised: 02/02/2024] [Accepted: 02/02/2024] [Indexed: 02/10/2024]
Abstract
The Hsp70 chaperone system is a central component of cellular protein quality control (PQC) by acting in a multitude of protein folding processes ranging from the folding of newly synthesized proteins to the disassembly and refolding of protein aggregates. This multifunctionality of Hsp70 is governed by J-domain proteins (JDPs), which act as indispensable co-chaperones that target specific substrates to Hsp70. The number of distinct JDPs present in a species always outnumbers Hsp70, documenting JDP function in functional diversification of Hsp70. In this review, we describe the physiological roles of JDPs in the Saccharomyces cerevisiae PQC system, with a focus on the abundant JDP generalists, Zuo1, Ydj1 and Sis1, which function in fundamental cellular processes. Ribosome-bound Zuo1 cooperates with the Hsp70 chaperones Ssb1/2 in folding and assembly of nascent polypeptides. Ydj1 and Sis1 cooperate with the Hsp70 members Ssa1 to Ssa4 to exert overlapping functions in protein folding and targeting of newly synthesized proteins to organelles including mitochondria and facilitating the degradation of aberrant proteins by E3 ligases. Furthermore, they act in protein disaggregation reactions, though Ydj1 and Sis1 differ in their modes of Hsp70 cooperation and substrate specificities. This results in functional specialization as seen in prion propagation and the underlying dominant role of Sis1 in targeting Hsp70 for shearing of prion amyloid fibrils.
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Affiliation(s)
- Carmen Ruger-Herreros
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Avda. Manuel Siurot, s/n, E-41013 Sevilla, Spain
| | - Lucia Svoboda
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
| | - Axel Mogk
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
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2
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Dea A, Pincus D. The Heat Shock Response as a Condensate Cascade. J Mol Biol 2024; 436:168642. [PMID: 38848866 PMCID: PMC11214683 DOI: 10.1016/j.jmb.2024.168642] [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: 11/07/2023] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/09/2024]
Abstract
The heat shock response (HSR) is a gene regulatory program controlling expression of molecular chaperones implicated in aging, cancer, and neurodegenerative disease. Long presumed to be activated by toxic protein aggregates, recent work suggests a new functional paradigm for the HSR in yeast. Rather than toxic aggregates, adaptive biomolecular condensates comprised of orphan ribosomal proteins (oRP) and stress granule components have been shown to be physiological chaperone clients. By titrating away the chaperones Sis1 and Hsp70 from the transcription factor Hsf1, these condensates activate the HSR. Upon release from Hsp70, Hsf1 forms spatially distinct transcriptional condensates that drive high expression of HSR genes. In this manner, the negative feedback loop controlling HSR activity - in which Hsf1 induces Hsp70 expression and Hsp70 represses Hsf1 activity - is embedded in the biophysics of the system. By analogy to phosphorylation cascades that transmit information via the dynamic activity of kinases, we propose that the HSR is organized as a condensate cascade that transmits information via the localized activity of molecular chaperones.
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Affiliation(s)
- Annisa Dea
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, United States
| | - David Pincus
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, United States; Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, United States; Center for Physics of Evolving Systems, University of Chicago, Chicago, IL, United States.
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3
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Cairo LV, Hong X, Müller MBD, Yuste-Checa P, Jagadeesan C, Bracher A, Park SH, Hayer-Hartl M, Hartl FU. Stress-dependent condensate formation regulated by the ubiquitin-related modifier Urm1. Cell 2024:S0092-8674(24)00649-4. [PMID: 38942013 DOI: 10.1016/j.cell.2024.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Revised: 04/12/2024] [Accepted: 06/08/2024] [Indexed: 06/30/2024]
Abstract
The ability of proteins and RNA to coalesce into phase-separated assemblies, such as the nucleolus and stress granules, is a basic principle in organizing membraneless cellular compartments. While the constituents of biomolecular condensates are generally well documented, the mechanisms underlying their formation under stress are only partially understood. Here, we show in yeast that covalent modification with the ubiquitin-like modifier Urm1 promotes the phase separation of a wide range of proteins. We find that the drop in cellular pH induced by stress triggers Urm1 self-association and its interaction with both target proteins and the Urm1-conjugating enzyme Uba4. Urmylation of stress-sensitive proteins promotes their deposition into stress granules and nuclear condensates. Yeast cells lacking Urm1 exhibit condensate defects that manifest in reduced stress resilience. We propose that Urm1 acts as a reversible molecular "adhesive" to drive protective phase separation of functionally critical proteins under cellular stress.
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Affiliation(s)
- Lucas V Cairo
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Xiaoyu Hong
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Martin B D Müller
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Patricia Yuste-Checa
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Chandhuru Jagadeesan
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Andreas Bracher
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Sae-Hun Park
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - Manajit Hayer-Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Martinsried, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
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4
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Rubio LS, Mohajan S, Gross DS. Heat Shock Factor 1 forms condensates and restructures the yeast genome before activating target genes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.28.560064. [PMID: 37808805 PMCID: PMC10557744 DOI: 10.1101/2023.09.28.560064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
In insects and mammals, 3D genome topology has been linked to transcriptional states yet whether this link holds for other eukaryotes is unclear. Using both ligation proximity and fluorescence microscopy assays, we show that in Saccharomyces cerevisiae, Heat Shock Response (HSR) genes dispersed across multiple chromosomes and under the control of Heat Shock Factor (Hsf1) rapidly reposition in cells exposed to acute ethanol stress and engage in concerted, Hsf1-dependent intergenic interactions. Accompanying 3D genome reconfiguration is equally rapid formation of Hsf1-containing condensates. However, in contrast to the transience of Hsf1-driven intergenic interactions that peak within 10-20 min and dissipate within 1 h in the presence of 8.5% (v/v) ethanol, transcriptional condensates are stably maintained for hours. Moreover, under the same conditions, Pol II occupancy of HSR genes and RNA expression are detectable only later in the response and peak much later (>1 h). This contrasts with the coordinate response of HSR genes to thermal stress (39°C) where Pol II occupancy, transcription, intergenic interactions, and formation of Hsf1 condensates are all rapid yet transient (peak within 2.5-10 min and dissipate within 1 h). Therefore, Hsf1 forms condensates, restructures the genome and transcriptionally activates HSR genes in response to both forms of proteotoxic stress but does so with strikingly different kinetics. In cells subjected to ethanol stress, Hsf1 forms condensates and repositions target genes before transcriptionally activating them.
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Affiliation(s)
- Linda S. Rubio
- Department of Biochemistry and Molecular Biology , Louisiana State University Health Sciences Center, Shreveport, LA 71130
| | - Suman Mohajan
- Department of Biochemistry and Molecular Biology , Louisiana State University Health Sciences Center, Shreveport, LA 71130
| | - David S. Gross
- Department of Biochemistry and Molecular Biology , Louisiana State University Health Sciences Center, Shreveport, LA 71130
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5
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Shen B, Coruzzi GM, Shasha D. Bipartite networks represent causality better than simple networks: evidence, algorithms, and applications. Front Genet 2024; 15:1371607. [PMID: 38798697 PMCID: PMC11120958 DOI: 10.3389/fgene.2024.1371607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 04/17/2024] [Indexed: 05/29/2024] Open
Abstract
A network, whose nodes are genes and whose directed edges represent positive or negative influences of a regulatory gene and its targets, is often used as a representation of causality. To infer a network, researchers often develop a machine learning model and then evaluate the model based on its match with experimentally verified "gold standard" edges. The desired result of such a model is a network that may extend the gold standard edges. Since networks are a form of visual representation, one can compare their utility with architectural or machine blueprints. Blueprints are clearly useful because they provide precise guidance to builders in construction. If the primary role of gene regulatory networks is to characterize causality, then such networks should be good tools of prediction because prediction is the actionable benefit of knowing causality. But are they? In this paper, we compare prediction quality based on "gold standard" regulatory edges from previous experimental work with non-linear models inferred from time series data across four different species. We show that the same non-linear machine learning models have better predictive performance, with improvements from 5.3% to 25.3% in terms of the reduction in the root mean square error (RMSE) compared with the same models based on the gold standard edges. Having established that networks fail to characterize causality properly, we suggest that causality research should focus on four goals: (i) predictive accuracy; (ii) a parsimonious enumeration of predictive regulatory genes for each target gene g; (iii) the identification of disjoint sets of predictive regulatory genes for each target g of roughly equal accuracy; and (iv) the construction of a bipartite network (whose node types are genes and models) representation of causality. We provide algorithms for all goals.
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Affiliation(s)
- Bingran Shen
- Courant Institute of Mathematical Sciences, Department of Computer Science, New York University, New York, United States
| | - Gloria M. Coruzzi
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, United States
| | - Dennis Shasha
- Courant Institute of Mathematical Sciences, Department of Computer Science, New York University, New York, United States
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6
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Bohn L, Huang J, Weidig S, Yang Z, Heidersberger C, Genty B, Falter-Braun P, Christmann A, Grill E. The temperature sensor TWA1 is required for thermotolerance in Arabidopsis. Nature 2024; 629:1126-1132. [PMID: 38750356 PMCID: PMC11136664 DOI: 10.1038/s41586-024-07424-x] [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: 04/26/2023] [Accepted: 04/15/2024] [Indexed: 05/31/2024]
Abstract
Plants exposed to incidences of excessive temperatures activate heat-stress responses to cope with the physiological challenge and stimulate long-term acclimation1,2. The mechanism that senses cellular temperature for inducing thermotolerance is still unclear3. Here we show that TWA1 is a temperature-sensing transcriptional co-regulator that is needed for basal and acquired thermotolerance in Arabidopsis thaliana. At elevated temperatures, TWA1 changes its conformation and allows physical interaction with JASMONATE-ASSOCIATED MYC-LIKE (JAM) transcription factors and TOPLESS (TPL) and TOPLESS-RELATED (TPR) proteins for repressor complex assembly. TWA1 is a predicted intrinsically disordered protein that has a key thermosensory role functioning through an amino-terminal highly variable region. At elevated temperatures, TWA1 accumulates in nuclear subdomains, and physical interactions with JAM2 and TPL appear to be restricted to these nuclear subdomains. The transcriptional upregulation of the heat shock transcription factor A2 (HSFA2) and heat shock proteins depended on TWA1, and TWA1 orthologues provided different temperature thresholds, consistent with the sensor function in early signalling of heat stress. The identification of the plant thermosensors offers a molecular tool for adjusting thermal acclimation responses of crops by breeding and biotechnology, and a sensitive temperature switch for thermogenetics.
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Affiliation(s)
- Lisa Bohn
- Chair of Botany, TUM School of Life Sciences Weihenstephan, Technische Universität München (TUM), Freising, Germany
| | - Jin Huang
- Chair of Botany, TUM School of Life Sciences Weihenstephan, Technische Universität München (TUM), Freising, Germany
- Chengdu Newsun Crop Science, Chengdu, China
| | - Susan Weidig
- Chair of Botany, TUM School of Life Sciences Weihenstephan, Technische Universität München (TUM), Freising, Germany
| | - Zhenyu Yang
- Chair of Botany, TUM School of Life Sciences Weihenstephan, Technische Universität München (TUM), Freising, Germany
| | - Christoph Heidersberger
- Chair of Botany, TUM School of Life Sciences Weihenstephan, Technische Universität München (TUM), Freising, Germany
| | - Bernard Genty
- Aix-Marseille University, Commissariat à l'Energie Atomique (CEA), Centre National de la Recherche Scientifique (CNRS), Institut de Biosciences et Biotechnologies Aix-Marseille, Saint-Paul-lez-Durance, France
| | - Pascal Falter-Braun
- Institute of Network Biology (INET), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Center Munich, German Research Center for Environmental Health, Munich, Germany
- Microbe-Host Interactions, Faculty of Biology, Ludwig-Maximilians-Universität (LMU) München, Munich, Germany
| | - Alexander Christmann
- Chair of Botany, TUM School of Life Sciences Weihenstephan, Technische Universität München (TUM), Freising, Germany.
| | - Erwin Grill
- Chair of Botany, TUM School of Life Sciences Weihenstephan, Technische Universität München (TUM), Freising, Germany.
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7
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Garde R, Dea A, Herwig MF, Pincus D. Feedback control of the heat shock response by spatiotemporal regulation of Hsp70. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.09.574867. [PMID: 38260373 PMCID: PMC10802473 DOI: 10.1101/2024.01.09.574867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Cells maintain homeostasis via dynamic regulation of stress response pathways. Stress pathways transiently induce response regulons via negative feedback loops, but the extent to which individual genes provide feedback has not been comprehensively measured for any pathway. Here, we disrupted induction of each gene in the Saccharomyces cerevisiae heat shock response (HSR) and quantified cell growth and HSR dynamics following heat shock. The screen revealed a core feedback loop governing expression of the chaperone Hsp70 reinforced by an auxiliary feedback loop controlling Hsp70 subcellular localization. Mathematical modeling and live imaging demonstrated that multiple HSR targets converge to promote Hsp70 nuclear localization via its release from cytosolic condensates. Following ethanol stress, a distinct set of factors similarly converged on Hsp70, suggesting that nonredundant subsets of the HSR regulon confer feedback under different conditions. Flexible spatiotemporal feedback loops may broadly organize stress response regulons and expand their adaptive capacity.
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Affiliation(s)
- Rania Garde
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL
- Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Chicago, IL
| | - Annisa Dea
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL
| | - Madeline F. Herwig
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL
| | - David Pincus
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL
- Center for Physics of Evolving Systems, University of Chicago, Chicago, IL
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8
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Eisele-Bürger AM, Eisele F, Malmgren Hill S, Hao X, Schneider KL, Imamoglu R, Balchin D, Liu B, Hartl FU, Bozhkov PV, Nyström T. Calmodulin regulates protease versus co-chaperone activity of a metacaspase. Cell Rep 2023; 42:113372. [PMID: 37938971 DOI: 10.1016/j.celrep.2023.113372] [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: 03/24/2023] [Revised: 09/11/2023] [Accepted: 10/19/2023] [Indexed: 11/10/2023] Open
Abstract
Metacaspases are ancestral homologs of caspases that can either promote cell death or confer cytoprotection. Furthermore, yeast (Saccharomyces cerevisiae) metacaspase Mca1 possesses dual biochemical activity: proteolytic activity causing cell death and cytoprotective, co-chaperone-like activity retarding replicative aging. The molecular mechanism favoring one activity of Mca1 over another remains elusive. Here, we show that this mechanism involves calmodulin binding to the N-terminal pro-domain of Mca1, which prevents its proteolytic activation and promotes co-chaperone-like activity, thus switching from pro-cell death to anti-aging function. The longevity-promoting effect of Mca1 requires the Hsp40 co-chaperone Sis1, which is necessary for Mca1 recruitment to protein aggregates and their clearance. In contrast, proteolytically active Mca1 cleaves Sis1 both in vitro and in vivo, further clarifying molecular mechanism behind a dual role of Mca1 as a cell-death protease versus gerontogene.
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Affiliation(s)
- Anna Maria Eisele-Bürger
- Department of Microbiology and Immunology, University of Gothenburg, 40530 Gothenburg, Sweden; Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, PO Box 7015, 75007 Uppsala, Sweden
| | - Frederik Eisele
- Department of Microbiology and Immunology, University of Gothenburg, 40530 Gothenburg, Sweden; Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90 Göteborg, Sweden
| | - Sandra Malmgren Hill
- Department of Microbiology and Immunology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Xinxin Hao
- Department of Microbiology and Immunology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Kara L Schneider
- Department of Microbiology and Immunology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Rahmi Imamoglu
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - David Balchin
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Beidong Liu
- Department of Chemistry and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90 Göteborg, Sweden
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Peter V Bozhkov
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, PO Box 7015, 75007 Uppsala, Sweden.
| | - Thomas Nyström
- Department of Microbiology and Immunology, University of Gothenburg, 40530 Gothenburg, Sweden.
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9
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Black JJ, Green R. Saving ribosomal proteins for later. Nat Cell Biol 2023; 25:1568-1569. [PMID: 37845326 DOI: 10.1038/s41556-023-01251-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Affiliation(s)
- Joshua J Black
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Rachel Green
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD, USA.
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10
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Ali A, Garde R, Schaffer OC, Bard JAM, Husain K, Kik SK, Davis KA, Luengo-Woods S, Igarashi MG, Drummond DA, Squires AH, Pincus D. Adaptive preservation of orphan ribosomal proteins in chaperone-dispersed condensates. Nat Cell Biol 2023; 25:1691-1703. [PMID: 37845327 PMCID: PMC10868727 DOI: 10.1038/s41556-023-01253-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 09/12/2023] [Indexed: 10/18/2023]
Abstract
Ribosome biogenesis is among the most resource-intensive cellular processes, with ribosomal proteins accounting for up to half of all newly synthesized proteins in eukaryotic cells. During stress, cells shut down ribosome biogenesis in part by halting rRNA synthesis, potentially leading to massive accumulation of aggregation-prone 'orphan' ribosomal proteins (oRPs). Here we show that, during heat shock in yeast and human cells, oRPs accumulate as reversible peri-nucleolar condensates recognized by the Hsp70 co-chaperone Sis1/DnaJB6. oRP condensates are liquid-like in cell-free lysate but solidify upon depletion of Sis1 or inhibition of Hsp70. When cells recover from heat shock, oRP condensates disperse in a Sis1- and Hsp70-dependent manner, and the oRP constituents are incorporated into functional ribosomes in the cytosol, enabling cells to efficiently resume growth. Preserving biomolecules in reversible condensates-like mRNAs in cytosolic stress granules and oRPs at the nucleolar periphery-may be a primary function of the Hsp70 chaperone system.
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Affiliation(s)
- Asif Ali
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA.
| | - Rania Garde
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
- Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Chicago, IL, USA
| | - Olivia C Schaffer
- Pritzker School for Molecular Engineering, University of Chicago, Chicago, IL, USA
| | - Jared A M Bard
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Kabir Husain
- Department of Physics, University of Chicago, Chicago, IL, USA
| | - Samantha Keyport Kik
- Committee on Genetics, Genomics, and Systems Biology, University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Kathleen A Davis
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
| | - Sofia Luengo-Woods
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA
| | - Maya G Igarashi
- Graduate Program in Biophysical Sciences, University of Chicago, Chicago, IL, USA
| | - D Allan Drummond
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
- Department of Medicine, Section of Genetic Medicine, University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
- Center for Physics of Evolving Systems, University of Chicago, Chicago, IL, USA
| | - Allison H Squires
- Pritzker School for Molecular Engineering, University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
- Center for Physics of Evolving Systems, University of Chicago, Chicago, IL, USA
| | - David Pincus
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA.
- Center for Physics of Evolving Systems, University of Chicago, Chicago, IL, USA.
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11
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Paxman J, Zhou Z, O'Laughlin R, Liu Y, Li Y, Tian W, Su H, Jiang Y, Holness SE, Stasiowski E, Tsimring LS, Pillus L, Hasty J, Hao N. Age-dependent aggregation of ribosomal RNA-binding proteins links deterioration in chromatin stability with challenges to proteostasis. eLife 2022; 11:e75978. [PMID: 36194205 PMCID: PMC9578700 DOI: 10.7554/elife.75978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 10/03/2022] [Indexed: 11/13/2022] Open
Abstract
Chromatin instability and protein homeostasis (proteostasis) stress are two well-established hallmarks of aging, which have been considered largely independent of each other. Using microfluidics and single-cell imaging approaches, we observed that, during the replicative aging of Saccharomyces cerevisiae, a challenge to proteostasis occurs specifically in the fraction of cells with decreased stability within the ribosomal DNA (rDNA). A screen of 170 yeast RNA-binding proteins identified ribosomal RNA (rRNA)-binding proteins as the most enriched group that aggregate upon a decrease in rDNA stability induced by inhibition of a conserved lysine deacetylase Sir2. Further, loss of rDNA stability induces age-dependent aggregation of rRNA-binding proteins through aberrant overproduction of rRNAs. These aggregates contribute to age-induced proteostasis decline and limit cellular lifespan. Our findings reveal a mechanism underlying the interconnection between chromatin instability and proteostasis stress and highlight the importance of cell-to-cell variability in aging processes.
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Affiliation(s)
- Julie Paxman
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
| | - Zhen Zhou
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
| | - Richard O'Laughlin
- Department of Bioengineering, University of California, San DiegoLa JollaUnited States
| | - Yuting Liu
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
| | - Yang Li
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
| | - Wanying Tian
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
| | - Hetian Su
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
| | - Yanfei Jiang
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
| | - Shayna E Holness
- Department of Chemistry and Biochemistry, University of California, San DiegoLa JollaUnited States
| | - Elizabeth Stasiowski
- Department of Bioengineering, University of California, San DiegoLa JollaUnited States
| | - Lev S Tsimring
- Synthetic Biology Institute, University of California, San DiegoLa JollaUnited States
| | - Lorraine Pillus
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
- UCSD Moores Cancer Center, University of California San, DiegoLa JollaUnited States
| | - Jeff Hasty
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
- Department of Bioengineering, University of California, San DiegoLa JollaUnited States
- Synthetic Biology Institute, University of California, San DiegoLa JollaUnited States
| | - Nan Hao
- Department of Molecular Biology, Division of Biological Sciences, University of California, San DiegoLa JollaUnited States
- Department of Bioengineering, University of California, San DiegoLa JollaUnited States
- Synthetic Biology Institute, University of California, San DiegoLa JollaUnited States
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12
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Meduri R, Rubio LS, Mohajan S, Gross DS. Phase-separation antagonists potently inhibit transcription and broadly increase nucleosome density. J Biol Chem 2022; 298:102365. [PMID: 35963432 PMCID: PMC9486037 DOI: 10.1016/j.jbc.2022.102365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 11/24/2022] Open
Abstract
Biomolecular condensates are self-organized membraneless bodies involved in many critical cellular activities, including ribosome biogenesis, protein synthesis, and gene transcription. Aliphatic alcohols are commonly used to study biomolecular condensates, but their effects on transcription are unclear. Here, we explore the impact of the aliphatic dialcohol, 1,6-hexanediol (1,6-HD), on Pol II transcription and nucleosome occupancy in budding yeast. As expected, 1,6-HD, a reagent effective in disrupting biomolecular condensates, strongly suppressed the thermal stress–induced transcription of Heat Shock Factor 1–regulated genes that have previously been shown to physically interact and coalesce into intranuclear condensates. Surprisingly, the isomeric dialcohol, 2,5-HD, typically used as a negative control, abrogated Heat Shock Factor 1–target gene transcription under the same conditions. Each reagent also abolished the transcription of genes that do not detectably coalesce, including Msn2/Msn4-regulated heat-inducible genes and constitutively expressed housekeeping genes. Thus, at elevated temperature (39 °C), HDs potently inhibit the transcription of disparate genes and as demonstrated by chromatin immunoprecipitation do so by abolishing occupancy of RNA polymerase in chromatin. Concurrently, histone H3 density increased at least twofold within all gene coding and regulatory regions examined, including quiescent euchromatic loci, silent heterochromatic loci, and Pol III-transcribed loci. Our results offer a caveat for the use of HDs in studying the role of condensates in transcriptional control and provide evidence that exposure to these reagents elicits a widespread increase in nucleosome density and a concomitant loss of both Pol II and Pol III transcription.
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Affiliation(s)
- Rajyalakshmi Meduri
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA
| | - Linda S Rubio
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA
| | - Suman Mohajan
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA
| | - David S Gross
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, USA.
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13
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Torii S, Rakic P. Tracking the Activation of Heat Shock Signaling in Cellular Protection and Damage. Cells 2022; 11:1561. [PMID: 35563865 PMCID: PMC9104565 DOI: 10.3390/cells11091561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 05/02/2022] [Accepted: 05/02/2022] [Indexed: 01/27/2023] Open
Abstract
Heat Shock (HS) signaling is activated in response to various types of cellular stress. This activation serves to protect cells from immediate threats in the surrounding environment. However, activation of HS signaling occurs in a heterogeneous manner within each cell population and can alter the epigenetic state of the cell, ultimately leading to long-term abnormalities in body function. Here, we summarize recent research findings obtained using molecular and genetic tools to track cells where HS signaling is activated. We then discuss the potential further applications of these tools, their limitations, and the necessary caveats in interpreting data obtained with these tools.
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Affiliation(s)
| | - Pasko Rakic
- Department of Neuroscience, School of Medicine, Yale University, New Haven, CT 06510, USA;
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14
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Spatial sequestration of misfolded proteins in neurodegenerative diseases. Biochem Soc Trans 2022; 50:759-771. [PMID: 35311889 DOI: 10.1042/bst20210862] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/28/2022] [Accepted: 03/02/2022] [Indexed: 12/12/2022]
Abstract
Properly folded, functional proteins are essential for cell health. Cells sustain protein homeostasis, or proteostasis, via protein quality control (PQC) mechanisms. It is currently hypothesized that a breakdown in proteostasis during ageing leads to the accumulation of protein aggregates in the cell and disease. Sequestration of misfolded proteins into PQC compartments represents one branch of the PQC network. In neurodegenerative diseases, certain proteins form abnormal protein deposits. Which PQC compartments house misfolded proteins associated with neurodegenerative diseases is still being investigated. It remains unclear if sequestration of these misfolded proteins is toxic or protective to the cell. Here, we review the current knowledge on various PQC compartments that form in the cell, the kinds of protein aggregates found in neurodegenerative diseases, and what is known about their sequestration. Understanding how protein sequestration occurs can shed light on why aggregates are toxic to the cell and are linked to neurodegenerative diseases like Huntington's, Alzheimer's, and Parkinson's diseases.
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15
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Yoo H, Bard JA, Pilipenko E, Drummond DA. Chaperones directly and efficiently disperse stress-triggered biomolecular condensates. Mol Cell 2022; 82:741-755.e11. [PMID: 35148816 PMCID: PMC8857057 DOI: 10.1016/j.molcel.2022.01.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 09/30/2021] [Accepted: 01/06/2022] [Indexed: 12/28/2022]
Abstract
Stresses such as heat shock trigger the formation of protein aggregates and the induction of a disaggregation system composed of molecular chaperones. Recent work reveals that several cases of apparent heat-induced aggregation, long thought to be the result of toxic misfolding, instead reflect evolved, adaptive biomolecular condensation, with chaperone activity contributing to condensate regulation. Here we show that the yeast disaggregation system directly disperses heat-induced biomolecular condensates of endogenous poly(A)-binding protein (Pab1) orders of magnitude more rapidly than aggregates of the most commonly used misfolded model substrate, firefly luciferase. Beyond its efficiency, heat-induced condensate dispersal differs from heat-induced aggregate dispersal in its molecular requirements and mechanistic behavior. Our work establishes a bona fide endogenous heat-induced substrate for long-studied heat shock proteins, isolates a specific example of chaperone regulation of condensates, and underscores needed expansion of the proteotoxic interpretation of the heat shock response to encompass adaptive, chaperone-mediated regulation.
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Affiliation(s)
- Haneul Yoo
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Jared A.M. Bard
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - Evgeny Pilipenko
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA
| | - D. Allan Drummond
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, 60637, USA,Department of Medicine, Section of Genetic Medicine, The University of Chicago, Chicago, IL, 60637, USA,Lead Contact,Correspondence: (D.A.D.)
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16
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Schilke BA, Craig EA. Essentiality of Sis1, a J-domain protein Hsp70 cochaperone, can be overcome by Tti1, a specialized PIKK chaperone. Mol Biol Cell 2021; 33:br3. [PMID: 34935410 PMCID: PMC9250385 DOI: 10.1091/mbc.e21-10-0493] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
J-domain protein cochaperones drive much of the functional diversity of Hsp70-based chaperone systems. Sis1 is the only essential J-domain protein of the cytosol/nucleus of Saccharomyces cerevisiae. Why it is required for cell growth is not understood, nor how critical its role is in regulation of heat shock transcription factor 1 (Hsf1). We report that single-residue substitutions in Tti1, a component of the heterotrimeric TTT complex, a specialized chaperone system for phosphatidylinositol 3-kinase-related kinase (PIKK) proteins, allow growth of cells lacking Sis1. Upon depletion of Sis1, cells become hypersensitive to rapamycin, a specific inhibitor of TORC1 kinase. In addition, levels of the three essential PIKKs (Mec1, Tra1, and Tor2), as well as Tor1, decrease upon Sis1 depletion. Overexpression of Tti1 allows growth without an increase in the other subunits of the TTT complex, Tel2 and Tti2, suggesting that it can function independent of the complex. Cells lacking Sis1, with viability supported by Tti1 suppressor, substantially up-regulate some, but not all, heat shock elements activated by Hsf1. Together, our results suggest that Sis1 is required as a cochaperone of Hsp70 for the folding/maintenance of PIKKs, making Sis1 an essential gene, and its requirement for Hsf1 regulation is more nuanced than generally appreciated.
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Affiliation(s)
- Brenda A Schilke
- Department of Biochemistry, 433 Babcock Drive, University of Wisconsin - Madison, Madison, Wisconsin 53706
| | - Elizabeth A Craig
- Department of Biochemistry, 433 Babcock Drive, University of Wisconsin - Madison, Madison, Wisconsin 53706
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17
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Kmiecik SW, Mayer MP. Molecular mechanisms of heat shock factor 1 regulation. Trends Biochem Sci 2021; 47:218-234. [PMID: 34810080 DOI: 10.1016/j.tibs.2021.10.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 10/08/2021] [Accepted: 10/22/2021] [Indexed: 02/06/2023]
Abstract
To thrive and to fulfill their functions, cells need to maintain proteome homeostasis even in the face of adverse environmental conditions or radical restructuring of the proteome during differentiation. At the center of the regulation of proteome homeostasis is an ancient transcriptional mechanism, the so-called heat shock response (HSR), orchestrated in all eukaryotic cells by heat shock transcription factor 1 (Hsf1). As Hsf1 is implicated in aging and several pathologies like cancer and neurodegenerative disorders, understanding the regulation of Hsf1 could open novel therapeutic opportunities. In this review, we discuss the regulation of Hsf1's transcriptional activity by multiple layers of control circuits involving Hsf1 synthesis and degradation, conformational rearrangements and post-translational modifications (PTMs), and molecular chaperones in negative feedback loops.
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Affiliation(s)
- Szymon W Kmiecik
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
| | - Matthias P Mayer
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH-Alliance, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany.
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18
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Transcriptional control of ribosome biogenesis in yeast: links to growth and stress signals. Biochem Soc Trans 2021; 49:1589-1599. [PMID: 34240738 PMCID: PMC8421047 DOI: 10.1042/bst20201136] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 12/15/2022]
Abstract
Ribosome biogenesis requires prodigious transcriptional output in rapidly growing yeast cells and is highly regulated in response to both growth and stress signals. This minireview focuses on recent developments in our understanding of this regulatory process, with an emphasis on the 138 ribosomal protein genes (RPGs) themselves and a group of >200 ribosome biogenesis (RiBi) genes whose products contribute to assembly but are not part of the ribosome. Expression of most RPGs depends upon Rap1, a pioneer transcription factor (TF) required for the binding of a pair of RPG-specific TFs called Fhl1 and Ifh1. RPG expression is correlated with Ifh1 promoter binding, whereas Rap1 and Fhl1 remain promoter-associated upon stress-induced down regulation. A TF called Sfp1 has also been implicated in RPG regulation, though recent work reveals that its primary function is in activation of RiBi and other growth-related genes. Sfp1 plays an important regulatory role at a small number of RPGs where Rap1–Fhl1–Ifh1 action is subsidiary or non-existent. In addition, nearly half of all RPGs are bound by Hmo1, which either stabilizes or re-configures Fhl1–Ifh1 binding. Recent studies identified the proline rotamase Fpr1, known primarily for its role in rapamycin-mediated inhibition of the TORC1 kinase, as an additional TF at RPG promoters. Fpr1 also affects Fhl1–Ifh1 binding, either independently or in cooperation with Hmo1. Finally, a major recent development was the discovery of a protein homeostasis mechanism driven by unassembled ribosomal proteins, referred to as the Ribosome Assembly Stress Response (RASTR), that controls RPG transcription through the reversible condensation of Ifh1.
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19
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Alford BD, Tassoni-Tsuchida E, Khan D, Work JJ, Valiant G, Brandman O. ReporterSeq reveals genome-wide dynamic modulators of the heat shock response across diverse stressors. eLife 2021; 10:57376. [PMID: 34223816 PMCID: PMC8257254 DOI: 10.7554/elife.57376] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/11/2021] [Indexed: 12/16/2022] Open
Abstract
Understanding cellular stress response pathways is challenging because of the complexity of regulatory mechanisms and response dynamics, which can vary with both time and the type of stress. We developed a reverse genetic method called ReporterSeq to comprehensively identify genes regulating a stress-induced transcription factor under multiple conditions in a time-resolved manner. ReporterSeq links RNA-encoded barcode levels to pathway-specific output under genetic perturbations, allowing pooled pathway activity measurements via DNA sequencing alone and without cell enrichment or single-cell isolation. We used ReporterSeq to identify regulators of the heat shock response (HSR), a conserved, poorly understood transcriptional program that protects cells from proteotoxicity and is misregulated in disease. Genome-wide HSR regulation in budding yeast was assessed across 15 stress conditions, uncovering novel stress-specific, time-specific, and constitutive regulators. ReporterSeq can assess the genetic regulators of any transcriptional pathway with the scale of pooled genetic screens and the precision of pathway-specific readouts.
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Affiliation(s)
- Brian D Alford
- Department of Biochemistry, Stanford University, Stanford, United States
| | - Eduardo Tassoni-Tsuchida
- Department of Biochemistry, Stanford University, Stanford, United States.,Department of Biology, Stanford University, Stanford, United States
| | - Danish Khan
- Department of Biochemistry, Stanford University, Stanford, United States
| | - Jeremy J Work
- Department of Biochemistry, Stanford University, Stanford, United States
| | - Gregory Valiant
- Department of Computer Science, Stanford University, Stanford, United States
| | - Onn Brandman
- Department of Biochemistry, Stanford University, Stanford, United States
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20
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Differential role of cytosolic Hsp70s in longevity assurance and protein quality control. PLoS Genet 2021; 17:e1008951. [PMID: 33428620 PMCID: PMC7822560 DOI: 10.1371/journal.pgen.1008951] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 01/22/2021] [Accepted: 10/14/2020] [Indexed: 12/14/2022] Open
Abstract
70 kDa heat shock proteins (Hsp70) are essential chaperones of the protein quality control network; vital for cellular fitness and longevity. The four cytosolic Hsp70’s in yeast, Ssa1-4, are thought to be functionally redundant but the absence of Ssa1 and Ssa2 causes a severe reduction in cellular reproduction and accelerates replicative aging. In our efforts to identify which Hsp70 activities are most important for longevity assurance, we systematically investigated the capacity of Ssa4 to carry out the different activities performed by Ssa1/2 by overproducing Ssa4 in cells lacking these Hsp70 chaperones. We found that Ssa4, when overproduced in cells lacking Ssa1/2, rescued growth, mitigated aggregate formation, restored spatial deposition of aggregates into protein inclusions, and promoted protein degradation. In contrast, Ssa4 overproduction in the Hsp70 deficient cells failed to restore the recruitment of the disaggregase Hsp104 to misfolded/aggregated proteins, to fully restore clearance of protein aggregates, and to bring back the formation of the nucleolus-associated aggregation compartment. Exchanging the nucleotide-binding domain of Ssa4 with that of Ssa1 suppressed this ‘defect’ of Ssa4. Interestingly, Ssa4 overproduction extended the short lifespan of ssa1Δ ssa2Δ mutant cells to a lifespan comparable to, or even longer than, wild type cells, demonstrating that Hsp104-dependent aggregate clearance is not a prerequisite for longevity assurance in yeast. All organisms have proteins that network together to stabilize and protect the cell throughout its lifetime. One of these types of proteins are the Hsp70s (heat shock protein 70). Hsp70 proteins take part in folding other proteins to their functional form, untangling proteins from aggregates, organize aggregates inside the cell and ensure that damaged proteins are destroyed. In this study, we investigated three closely related Hsp70 proteins in yeast; Ssa1, 2 and 4, in an effort to describe the functional difference of Ssa4 compared to Ssa1 and 2 and to answer the question: What types of cellular stress protection are necessary to reach a normal lifespan? We show that Ssa4 can perform many of the same tasks as Ssa1 and 2, but Ssa4 doesn’t interact in the same manner as Ssa1 and 2 with other types of proteins. This leads to a delay in removing protein aggregates created after heat stress. Ssa4 also cannot ensure that misfolded proteins aggregate correctly inside the nucleus of the cell. However, this turns out not to be necessary for yeast cells to achieve a full lifespan, which shows us that as long as cells can prevent aggregates from forming in the first place, they can reach a full lifespan.
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21
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Abstract
The heat shock response (HSR) is a gene expression program that protects cells from heat and proteotoxic stressors. In this issue, Feder et al. (2020. J. Cell Biol.https://doi.org/10.1083/jcb.202005165) show that subcellular relocalization of the cochaperone Sis1 drives the HSR by de-suppressing the transcription factor Hsf1.
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Affiliation(s)
| | - Onn Brandman
- Department of Biochemistry, Stanford University, Stanford, CA
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