1
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Chvalova V, Vomastek T, Grousl T. Comparison of holotomographic microscopy and coherence-controlled holographic microscopy. J Microsc 2024; 294:5-13. [PMID: 38196346 DOI: 10.1111/jmi.13260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/18/2023] [Accepted: 12/26/2023] [Indexed: 01/11/2024]
Abstract
Quantitative phase imaging (QPI) is a powerful tool for label-free visualisation of living cells. Here, we compare two QPI microscopes - the Telight Q-Phase microscope and the Nanolive 3D Cell Explorer-fluo microscope. Both systems provide unbiased information about cell morphology, such as individual cell dry mass, perimeter and area. The Q-Phase microscope uses artefact-free, coherence-controlled holographic imaging technology to visualise cells in real time with minimal phototoxicity. The 3D Cell Explorer-fluo employs laser-based holotomography to reconstruct 3D images of living cells, visualising their internal structures and dynamics. Here, we analysed the strengths and limitations of both microscopes when examining two morphologically distinct cell lines - the cuboidal epithelial MDCK cells which form multicellular clusters and solitary growing Rat2 fibroblasts. We focus mainly on the ability of the devices to generate images suitable for single-cell segmentation by the built-in software, and we discuss the segmentation results and quantitative data generated from the segmented images. We show that both microscopes offer slightly different advantages, and the choice between them depends on the specific requirements and goals of the user.
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Affiliation(s)
- Vera Chvalova
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
- Faculty of Science, Department of Cell Biology, Charles University, Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Tomas Grousl
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
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2
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Chvalova V, Venkadasubramanian V, Klimova Z, Vojtova J, Benada O, Vanatko O, Vomastek T, Grousl T. Characterization of RACK1-depleted mammalian cells by a palette of microscopy approaches reveals defects in cell cycle progression and polarity establishment. Exp Cell Res 2023:113695. [PMID: 37393981 DOI: 10.1016/j.yexcr.2023.113695] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 06/08/2023] [Accepted: 06/22/2023] [Indexed: 07/04/2023]
Abstract
The Receptor for Activated C Kinase 1 (RACK1) is an evolutionarily conserved scaffold protein involved in the regulation of numerous cellular processes. Here, we used CRISPR/Cas9 and siRNA to reduce the expression of RACK1 in Madin-Darby Canine Kidney (MDCK) epithelial cells and Rat2 fibroblasts, respectively. RACK1-depleted cells were examined using coherence-controlled holographic microscopy, immunofluorescence, and electron microscopy. RACK1 depletion resulted in decreased cell proliferation, increased cell area and perimeter, and in the appearance of large binucleated cells suggesting a defect in the cell cycle progression. Our results show that the depletion of RACK1 has a pleiotropic effect on both epithelial and mesenchymal cell lines and support its essential role in mammalian cells.
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Affiliation(s)
- Vera Chvalova
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic; Faculty of Science, Charles University, 128 00, Prague, Czech Republic
| | - Vignesh Venkadasubramanian
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic; Faculty of Science, Charles University, 128 00, Prague, Czech Republic
| | - Zuzana Klimova
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic
| | - Jana Vojtova
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, 142 00, Prague, Czech Republic
| | - Oldrich Benada
- Laboratory of Molecular Structure Characterization, Institute of Microbiology of the Czech Academy of Sciences, 142 00, Prague, Czech Republic
| | - Ondrej Vanatko
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the Czech Academy of Sciences, 142 00, Prague, Czech Republic; Second Faculty of Medicine, Charles University, 150 06, Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic
| | - Tomas Grousl
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 00, Prague, Czech Republic.
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3
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Jawed A, Ho CT, Grousl T, Shrivastava A, Ruppert T, Bukau B, Mogk A. Balanced activities of Hsp70 and the ubiquitin proteasome system underlie cellular protein homeostasis. Front Mol Biosci 2023; 9:1106477. [PMID: 36660429 PMCID: PMC9845930 DOI: 10.3389/fmolb.2022.1106477] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 12/15/2022] [Indexed: 01/05/2023] Open
Abstract
To counteract proteotoxic stress and cellular aging, protein quality control (PQC) systems rely on the refolding, degradation and sequestration of misfolded proteins. In Saccharomyces cerevisiae the Hsp70 chaperone system plays a central role in protein refolding, while degradation is predominantly executed by the ubiquitin proteasome system (UPS). The sequestrases Hsp42 and Btn2 deposit misfolded proteins in cytosolic and nuclear inclusions, thereby restricting the accessibility of misfolded proteins to Hsp70 and preventing the exhaustion of limited Hsp70 resources. Therefore, in yeast, sequestrase mutants show negative genetic interactions with double mutants lacking the Hsp70 co-chaperone Fes1 and the Hsp104 disaggregase (fes1Δ hsp104Δ, ΔΔ) and suffering from low Hsp70 capacity. Growth of ΔΔbtn2Δ mutants is highly temperature-sensitive and results in proteostasis breakdown at non-permissive temperatures. Here, we probed for the role of the ubiquitin proteasome system in maintaining protein homeostasis in ΔΔbtn2Δ cells, which are affected in two major protein quality control branches. We show that ΔΔbtn2Δ cells induce expression of diverse stress-related pathways including the ubiquitin proteasome system to counteract the proteostasis defects. Ubiquitin proteasome system dependent degradation of the stringent Hsp70 substrate firefly Luciferase in the mutant cells mirrors such compensatory activities of the protein quality control system. Surprisingly however, the enhanced ubiquitin proteasome system activity does not improve but aggravates the growth defects of ΔΔbtn2Δ cells. Reducing ubiquitin proteasome system activity in the mutant by lowering the levels of functional 26S proteasomes improved growth, increased refolding yield of the Luciferase reporter and attenuated global stress responses. Our findings indicate that an imbalance between Hsp70-dependent refolding, sequestration and ubiquitin proteasome system-mediated degradation activities strongly affects protein homeostasis of Hsp70 capacity mutants and contributes to their severe growth phenotypes.
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Affiliation(s)
- Areeb Jawed
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Chi-Ting Ho
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Tomas Grousl
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Aseem Shrivastava
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Thomas Ruppert
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany,*Correspondence: Axel Mogk, ; Bernd Bukau,
| | - Axel Mogk
- Center for Molecular Biology of Heidelberg University (ZMBH), University of Heidelberg, Heidelberg, Germany,German Cancer Research Center (DKFZ), Heidelberg, Germany,*Correspondence: Axel Mogk, ; Bernd Bukau,
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4
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Rasl J, Grusanovic J, Klimova Z, Caslavsky J, Grousl T, Novotny J, Kolar M, Vomastek T. ERK2 signaling regulates cell-cell adhesion of epithelial cells and enhances growth factor-induced cell scattering. Cell Signal 2022; 99:110431. [PMID: 35933033 DOI: 10.1016/j.cellsig.2022.110431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/13/2022] [Accepted: 08/01/2022] [Indexed: 11/30/2022]
Abstract
The ERK signaling pathway, consisting of core protein kinases Raf, MEK and effector kinases ERK1/2, regulates various biological outcomes such as cell proliferation, differentiation, apoptosis, or cell migration. Signal transduction through the ERK signaling pathway is tightly controlled at all levels of the pathway. However, it is not well understood whether ERK pathway signaling can be modulated by the abundance of ERK pathway core kinases. In this study, we investigated the effects of low-level overexpression of the ERK2 isoform on the phenotype and scattering of cuboidal MDCK epithelial cells growing in discrete multicellular clusters. We show that ERK2 overexpression reduced the vertical size of lateral membranes that contain cell-cell adhesion complexes. Consequently, ERK2 overexpressing cells were unable to develop cuboidal shape, remained flat with increased spread area and intercellular adhesive contacts were present only on the basal side. Interestingly, ERK2 overexpression was not sufficient to increase phosphorylation of multiple downstream targets including transcription factors and induce global changes in gene expression, namely to increase the expression of pro-migratory transcription factor Fra1. However, ERK2 overexpression enhanced HGF/SF-induced cell scattering as these cells scattered more rapidly and to a greater extent than parental cells. Our results suggest that an increase in ERK2 expression primarily reduces cell-cell cohesion and that weakened intercellular adhesion synergizes with upstream signaling in the conversion of the multicellular epithelium into single migrating cells. This mechanism may be clinically relevant as the analysis of clinical data revealed that in one type of cancer, pancreatic adenocarcinoma, ERK2 overexpression correlates with a worse prognosis.
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Affiliation(s)
- Jan Rasl
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic; Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Josipa Grusanovic
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Zuzana Klimova
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Josef Caslavsky
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Tomas Grousl
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic
| | - Jiri Novotny
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic; Department of Informatics and Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, 160 00 Prague, Czech Republic
| | - Michal Kolar
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling Institute of Microbiology of the Czech Academy of Sciences, 142 00 Prague, Czech Republic.
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5
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Grousl T, Vojtova J, Hasek J, Vomastek T. Yeast stress granules at a glance. Yeast 2021; 39:247-261. [PMID: 34791685 DOI: 10.1002/yea.3681] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 10/15/2021] [Accepted: 11/12/2021] [Indexed: 11/10/2022] Open
Abstract
The formation of stress granules (SGs), membrane-less organelles that are composed of mainly messenger ribonucleoprotein assemblies, is the result of a conserved evolutionary strategy to cellular stress. During their formation, which is triggered by robust environmental stress, SGs sequester translationally inactive mRNA molecules, which are either forwarded for further processing elsewhere or stored during a period of stress within SGs. Removal of mRNA molecules from active translation and their sequestration in SGs allows preferential translation of stress response transcripts. By affecting the specificity of mRNA translation, mRNA localization and stability, SGs are involved in the overall cellular reprogramming during periods of environmental stress and viral infection. Over the past two decades, we have learned which processes drive SGs assembly, how their composition varies under stress, and how they co-exist with other subcellular organelles. Yeast as a model has been instrumental in our understanding of SG biology. Despite the specific differences between the SGs of yeast and mammals, yeast have been shown to be a valuable tool to the study of SGs in translation-related stress response. This review summarizes the data surrounding SGs that are formed under different stress conditions in Saccharomyces cerevisiae and other yeast species. It offers a comprehensive and up-to-date view on these still somewhat mysterious entities.
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Affiliation(s)
- Tomas Grousl
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jana Vojtova
- Laboratory of Cell Reproduction, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jiri Hasek
- Laboratory of Cell Reproduction, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Tomas Vomastek
- Laboratory of Cell Signalling, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
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6
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Ho CT, Grousl T, Shatz O, Jawed A, Ruger-Herreros C, Semmelink M, Zahn R, Richter K, Bukau B, Mogk A. Cellular sequestrases maintain basal Hsp70 capacity ensuring balanced proteostasis. Nat Commun 2019; 10:4851. [PMID: 31649258 PMCID: PMC6813348 DOI: 10.1038/s41467-019-12868-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 10/07/2019] [Indexed: 12/19/2022] Open
Abstract
Maintenance of cellular proteostasis is achieved by a multi-layered quality control network, which counteracts the accumulation of misfolded proteins by refolding and degradation pathways. The organized sequestration of misfolded proteins, actively promoted by cellular sequestrases, represents a third strategy of quality control. Here we determine the role of sequestration within the proteostasis network in Saccharomyces cerevisiae and the mechanism by which it occurs. The Hsp42 and Btn2 sequestrases are functionally intertwined with the refolding activity of the Hsp70 system. Sequestration of misfolded proteins by Hsp42 and Btn2 prevents proteostasis collapse and viability loss in cells with limited Hsp70 capacity, likely by shielding Hsp70 from misfolded protein overload. Btn2 has chaperone and sequestrase activity and shares features with small heat shock proteins. During stress recovery Btn2 recruits the Hsp70-Hsp104 disaggregase by directly interacting with the Hsp70 co-chaperone Sis1, thereby shunting sequestered proteins to the refolding pathway.
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Affiliation(s)
- Chi-Ting Ho
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany.,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Tomas Grousl
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany.,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany.,Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Oren Shatz
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany.,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Areeb Jawed
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany.,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Carmen Ruger-Herreros
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany.,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Marije Semmelink
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany.,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Regina Zahn
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany.,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Karsten Richter
- German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Bernd Bukau
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany. .,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany.
| | - Axel Mogk
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, DKFZ-ZMBH Alliance, Heidelberg, Germany. .,German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany.
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7
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Grousl T, Ungelenk S, Miller S, Ho CT, Khokhrina M, Mayer MP, Bukau B, Mogk A. A prion-like domain in Hsp42 drives chaperone-facilitated aggregation of misfolded proteins. J Cell Biol 2018; 217:1269-1285. [PMID: 29362223 PMCID: PMC5881502 DOI: 10.1083/jcb.201708116] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 12/07/2017] [Accepted: 01/08/2018] [Indexed: 12/31/2022] Open
Abstract
The facilitated aggregation of misfolded proteins is a proteostasis strategy important for cell function and viability, but the molecular mechanisms are poorly understood. Grousl et al. reveal how the intrinsically disordered domains of the small heat shock protein Hsp42 promote and control the aggregation of misfolded proteins during stress conditions in yeast. Chaperones with aggregase activity promote and organize the aggregation of misfolded proteins and their deposition at specific intracellular sites. This activity represents a novel cytoprotective strategy of protein quality control systems; however, little is known about its mechanism. In yeast, the small heat shock protein Hsp42 orchestrates the stress-induced sequestration of misfolded proteins into cytosolic aggregates (CytoQ). In this study, we show that Hsp42 harbors a prion-like domain (PrLD) and a canonical intrinsically disordered domain (IDD) that act coordinately to promote and control protein aggregation. Hsp42 PrLD is essential for CytoQ formation and is bifunctional, mediating self-association as well as binding to misfolded proteins. Hsp42 IDD confines chaperone and aggregase activity and affects CytoQ numbers and stability in vivo. Hsp42 PrLD and IDD are both crucial for cellular fitness during heat stress, demonstrating the need for sequestering misfolded proteins in a regulated manner.
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Affiliation(s)
- Tomas Grousl
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Sophia Ungelenk
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Stephanie Miller
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Chi-Ting Ho
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Maria Khokhrina
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Matthias P Mayer
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Bernd Bukau
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany .,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
| | - Axel Mogk
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany .,Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
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8
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Ungelenk S, Moayed F, Ho CT, Grousl T, Scharf A, Mashaghi A, Tans S, Mayer MP, Mogk A, Bukau B. Small heat shock proteins sequester misfolding proteins in near-native conformation for cellular protection and efficient refolding. Nat Commun 2016; 7:13673. [PMID: 27901028 PMCID: PMC5141385 DOI: 10.1038/ncomms13673] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 10/24/2016] [Indexed: 12/30/2022] Open
Abstract
Small heat shock proteins (sHsp) constitute an evolutionary conserved yet diverse family of chaperones acting as first line of defence against proteotoxic stress. sHsps coaggregate with misfolded proteins but the molecular basis and functional implications of these interactions, as well as potential sHsp specific differences, are poorly explored. In a comparative analysis of the two yeast sHsps, Hsp26 and Hsp42, we show in vitro that model substrates retain near-native state and are kept physically separated when complexed with either sHsp, while being completely unfolded when aggregated without sHsps. Hsp42 acts as aggregase to promote protein aggregation and specifically ensures cellular fitness during heat stress. Hsp26 in contrast lacks aggregase function but is superior in facilitating Hsp70/Hsp100-dependent post-stress refolding. Our findings indicate the sHsps of a cell functionally diversify in stress defence, but share the working principle to promote sequestration of misfolding proteins for storage in native-like conformation.
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Affiliation(s)
- Sophia Ungelenk
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.,German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany
| | - Fatemeh Moayed
- FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, Amsterdam 1098 XG, The Netherlands
| | - Chi-Ting Ho
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.,German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany
| | - Tomas Grousl
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.,German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany
| | - Annette Scharf
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
| | - Alireza Mashaghi
- FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, Amsterdam 1098 XG, The Netherlands
| | - Sander Tans
- FOM Institute for Atomic and Molecular Physics (AMOLF), Science Park 104, Amsterdam 1098 XG, The Netherlands
| | - Matthias P Mayer
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
| | - Axel Mogk
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.,German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany
| | - Bernd Bukau
- Center for Molecular Biology of the University of Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.,German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany
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9
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Rinnerthaler M, Lejskova R, Grousl T, Stradalova V, Heeren G, Richter K, Breitenbach-Koller L, Malinsky J, Hasek J, Breitenbach M. Mmi1, the yeast homologue of mammalian TCTP, associates with stress granules in heat-shocked cells and modulates proteasome activity. PLoS One 2013; 8:e77791. [PMID: 24204967 PMCID: PMC3810133 DOI: 10.1371/journal.pone.0077791] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 09/04/2013] [Indexed: 12/28/2022] Open
Abstract
As we have shown previously, yeast Mmi1 protein translocates from the cytoplasm to the outer surface of mitochondria when vegetatively growing yeast cells are exposed to oxidative stress. Here we analyzed the effect of heat stress on Mmi1 distribution. We performed domain analyses and found that binding of Mmi1 to mitochondria is mediated by its central alpha-helical domain (V-domain) under all conditions tested. In contrast, the isolated N-terminal flexible loop domain of the protein always displays nuclear localization. Using immunoelectron microscopy we confirmed re-location of Mmi1 to the nucleus and showed association of Mmi1 with intact and heat shock-altered mitochondria. We also show here that mmi1Δ mutant strains are resistant to robust heat shock with respect to clonogenicity of the cells. To elucidate this phenotype we found that the cytosolic Mmi1 holoprotein re-localized to the nucleus even in cells heat-shocked at 40°C. Upon robust heat shock at 46°C, Mmi1 partly co-localized with the proteasome marker Rpn1 in the nuclear region as well as with the cytoplasmic stress granules defined by Rpg1 (eIF3a). We co-localized Mmi1 also with Bre5, Ubp3 and Cdc48 which are involved in the protein de-ubiquitination machinery, protecting protein substrates from proteasomal degradation. A comparison of proteolytic activities of wild type and mmi1Δ cells revealed that Mmi1 appears to be an inhibitor of the proteasome. We conclude that one of the physiological functions of the multifunctional protein module, Mmi1, is likely in regulating degradation and/or protection of proteins thereby indirectly regulating the pathways leading to cell death in stressed cells.
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Affiliation(s)
- Mark Rinnerthaler
- Department Cell Biology, Division Genetics, University of Salzburg, Salzburg, Austria
| | - Renata Lejskova
- Laboratory of Cell Reproduction, Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | - Tomas Grousl
- Laboratory of Cell Reproduction, Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | - Vendula Stradalova
- Microscopy Unit, Institute of Experimental Medicine of AS CR, v.v.i., Prague, Czech Republic
| | - Gino Heeren
- Department Cell Biology, Division Genetics, University of Salzburg, Salzburg, Austria
| | - Klaus Richter
- Department Cell Biology, Division Genetics, University of Salzburg, Salzburg, Austria
| | | | - Jan Malinsky
- Microscopy Unit, Institute of Experimental Medicine of AS CR, v.v.i., Prague, Czech Republic
| | - Jiri Hasek
- Laboratory of Cell Reproduction, Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
- * E-mail: (JH); (MB)
| | - Michael Breitenbach
- Department Cell Biology, Division Genetics, University of Salzburg, Salzburg, Austria
- * E-mail: (JH); (MB)
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Grousl T, Ivanov P, Malcova I, Pompach P, Frydlova I, Slaba R, Senohrabkova L, Novakova L, Hasek J. Heat shock-induced accumulation of translation elongation and termination factors precedes assembly of stress granules in S. cerevisiae. PLoS One 2013; 8:e57083. [PMID: 23451152 PMCID: PMC3581570 DOI: 10.1371/journal.pone.0057083] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 01/17/2013] [Indexed: 12/26/2022] Open
Abstract
In response to severe environmental stresses eukaryotic cells shut down translation and accumulate components of the translational machinery in stress granules (SGs). Since they contain mainly mRNA, translation initiation factors and 40S ribosomal subunits, they have been referred to as dominant accumulations of stalled translation preinitiation complexes. Here we present evidence that the robust heat shock-induced SGs of S. cerevisiae also contain translation elongation factors eEF3 (Yef3p) and eEF1Bγ2 (Tef4p) as well as translation termination factors eRF1 (Sup45p) and eRF3 (Sup35p). Despite the presence of the yeast prion protein Sup35 in heat shock-induced SGs, we found out that its prion-like domain is not involved in the SGs assembly. Factors eEF3, eEF1Bγ2 and eRF1 were accumulated and co-localized with Dcp2 foci even upon a milder heat shock at 42°C independently of P-bodies scaffolding proteins. We also show that eEF3 accumulations at 42°C determine sites of the genuine SGs assembly at 46°C. We suggest that identification of translation elongation and termination factors in SGs might help to understand the mechanism of the eIF2α factor phosphorylation-independent repression of translation and SGs assembly.
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Affiliation(s)
- Tomas Grousl
- Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | - Pavel Ivanov
- Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | - Ivana Malcova
- Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | - Petr Pompach
- Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | - Ivana Frydlova
- Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | - Renata Slaba
- Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | | | - Lenka Novakova
- Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
| | - Jiri Hasek
- Institute of Microbiology of AS CR, v.v.i., Prague, Czech Republic
- * E-mail:
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