1
|
Lippi A, Krisko A. Protein aggregation: A detrimental symptom or an adaptation mechanism? J Neurochem 2024; 168:1426-1441. [PMID: 37694504 DOI: 10.1111/jnc.15955] [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: 05/05/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 09/12/2023]
Abstract
Protein quality control mechanisms oversee numerous aspects of protein lifetime. From the point of protein synthesis, protein homeostasis machineries take part in folding, solubilization, and/or degradation of impaired proteins. Some proteins follow an alternative path upon loss of their solubility, thus are secluded from the cytosol and form protein aggregates. Protein aggregates differ in their function and composition, rendering protein aggregation a complex phenomenon that continues to receive plenty of attention in the scientific and medical communities. Traditionally, protein aggregates have been associated with aging and a large spectrum of protein folding diseases, such as neurodegenerative diseases, type 2 diabetes, or cataract. However, a body of evidence suggests that they may act as an adaptive mechanism to overcome transient stressful conditions, serving as a sink for the removal of misfolded proteins from the cytosol or storage compartments for machineries required upon stress release. In this review, we present examples and evidence elaborating different possible roles of protein aggregation and discuss their potential roles in stress survival, aging, and disease, as well as possible anti-aggregation interventions.
Collapse
Affiliation(s)
- Alice Lippi
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Anita Krisko
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| |
Collapse
|
2
|
Xie Y, Shu T, Liu T, Spindler MC, Mahamid J, Hocky GM, Gresham D, Holt LJ. Polysome collapse and RNA condensation fluidize the cytoplasm. Mol Cell 2024; 84:2698-2716.e9. [PMID: 39059370 DOI: 10.1016/j.molcel.2024.06.024] [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: 07/14/2023] [Revised: 03/25/2024] [Accepted: 06/24/2024] [Indexed: 07/28/2024]
Abstract
The cell interior is packed with macromolecules of mesoscale size, and this crowded milieu significantly influences cellular physiology. Cellular stress responses almost universally lead to inhibition of translation, resulting in polysome collapse and release of mRNA. The released mRNA molecules condense with RNA-binding proteins to form ribonucleoprotein (RNP) condensates known as processing bodies and stress granules. Here, we show that polysome collapse and condensation of RNA transiently fluidize the cytoplasm, and coarse-grained molecular dynamic simulations support this as a minimal mechanism for the observed biophysical changes. Increased mesoscale diffusivity correlates with the efficient formation of quality control bodies (Q-bodies), membraneless organelles that compartmentalize misfolded peptides during stress. Synthetic, light-induced RNA condensation also fluidizes the cytoplasm. Together, our study reveals a functional role for stress-induced translation inhibition and formation of RNP condensates in modulating the physical properties of the cytoplasm to enable efficient response of cells to stress conditions.
Collapse
Affiliation(s)
- Ying Xie
- Institute for Systems Genetics, New York University Langone Medical Center, New York, NY, USA; Department of Biology, New York University, New York, NY, USA
| | - Tong Shu
- Institute for Systems Genetics, New York University Langone Medical Center, New York, NY, USA
| | - Tiewei Liu
- Institute for Systems Genetics, New York University Langone Medical Center, New York, NY, USA; Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Marie-Christin Spindler
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany; Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
| | - Glen M Hocky
- Department of Chemistry and Simons Center for Computational Physical Chemistry, New York University, New York, NY, USA
| | - David Gresham
- Department of Biology, New York University, New York, NY, USA.
| | - Liam J Holt
- Institute for Systems Genetics, New York University Langone Medical Center, New York, NY, USA.
| |
Collapse
|
3
|
Creamer DR, Beynon RJ, Hubbard SJ, Ashe MP, Grant CM. Isoform-specific sequestration of protein kinase A fine-tunes intracellular signaling during heat stress. Cell Rep 2024; 43:114360. [PMID: 38865242 DOI: 10.1016/j.celrep.2024.114360] [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: 12/22/2023] [Revised: 04/24/2024] [Accepted: 05/30/2024] [Indexed: 06/14/2024] Open
Abstract
Protein kinase A (PKA) is a conserved kinase crucial for fundamental biological processes linked to growth, development, and metabolism. The PKA catalytic subunit is expressed as multiple isoforms in diverse eukaryotes; however, their contribution to ensuring signaling specificity in response to environmental cues remains poorly defined. Catalytic subunit activity is classically moderated via interaction with an inhibitory regulatory subunit. Here, a quantitative mass spectrometry approach is used to examine heat-stress-induced changes in the binding of yeast Tpk1-3 catalytic subunits to the Bcy1 regulatory subunit. We show that Tpk3 is not regulated by Bcy1 binding but, instead, is deactivated upon heat stress via reversible sequestration into cytoplasmic granules. These "Tpk3 granules" are enriched for multiple PKA substrates involved in various metabolic processes, with the Hsp42 sequestrase required for their formation. Hence, regulated sequestration of Tpk3 provides a mechanism to control isoform-specific kinase signaling activity during stress conditions.
Collapse
Affiliation(s)
- Declan R Creamer
- Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Robert J Beynon
- Centre for Proteome Research, Institute of Systems and Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Simon J Hubbard
- Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Mark P Ashe
- Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Chris M Grant
- Faculty of Biology, Medicine and Health, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Li C, Hao B, Yang H, Wang K, Fan L, Xiao W. Protein aggregation and biomolecular condensation in hypoxic environments (Review). Int J Mol Med 2024; 53:33. [PMID: 38362920 PMCID: PMC10903932 DOI: 10.3892/ijmm.2024.5357] [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: 11/08/2023] [Accepted: 01/15/2024] [Indexed: 02/17/2024] Open
Abstract
Due to molecular forces, biomacromolecules assemble into liquid condensates or solid aggregates, and their corresponding formation and dissolution processes are controlled. Protein homeostasis is disrupted by increasing age or environmental stress, leading to irreversible protein aggregation. Hypoxic pressure is an important factor in this process, and uncontrolled protein aggregation has been widely observed in hypoxia‑related conditions such as neurodegenerative disease, cardiovascular disease, hypoxic brain injury and cancer. Biomolecular condensates are also high‑order complexes assembled from macromolecules. Although they exist in different phase from protein aggregates, they are in dynamic balance under certain conditions, and their activation or assembly are considered as important regulatory processes in cell survival with hypoxic pressure. Therefore, a better understanding of the relationship between hypoxic stress, protein aggregation and biomolecular condensation will bring marked benefits in the clinical treatment of various diseases. The aim of the present review was to summarize the underlying mechanisms of aggregate assembly and dissolution induced by hypoxic conditions, and address recent breakthroughs in understanding the role of aggregates in hypoxic‑related diseases, given the hypotheses that hypoxia induces macromolecular assemblage changes from a liquid to a solid phase, and that adenosine triphosphate depletion and ATP‑driven inactivation of multiple protein chaperones play important roles among the process. Moreover, it is anticipated that an improved understanding of the adaptation in hypoxic environments could extend the overall survival of patients and provide new strategies for hypoxic‑related diseases.
Collapse
Affiliation(s)
- Chaoqun Li
- School of Exercise and Health, Shanghai University of Sport, Shanghai 200438, P.R. China
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Bingjie Hao
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Haiguang Yang
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Kai Wang
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Lihong Fan
- School of Exercise and Health, Shanghai University of Sport, Shanghai 200438, P.R. China
- Institute of Energy Metabolism and Health, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
| | - Weihua Xiao
- School of Exercise and Health, Shanghai University of Sport, Shanghai 200438, P.R. China
| |
Collapse
|
6
|
Eltayeb A, Al-Sarraj F, Alharbi M, Albiheyri R, Mattar EH, Abu Zeid IM, Bouback TA, Bamagoos A, Uversky VN, Rubio-Casillas A, Redwan EM. Intrinsic factors behind long COVID: IV. Hypothetical roles of the SARS-CoV-2 nucleocapsid protein and its liquid-liquid phase separation. J Cell Biochem 2024; 125:e30530. [PMID: 38349116 DOI: 10.1002/jcb.30530] [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: 09/09/2023] [Revised: 01/10/2024] [Accepted: 01/24/2024] [Indexed: 03/12/2024]
Abstract
When the SARS-CoV-2 virus infects humans, it leads to a condition called COVID-19 that has a wide spectrum of clinical manifestations, from no symptoms to acute respiratory distress syndrome. The virus initiates damage by attaching to the ACE-2 protein on the surface of endothelial cells that line the blood vessels and using these cells as hosts for replication. Reactive oxygen species levels are increased during viral replication, which leads to oxidative stress. About three-fifths (~60%) of the people who get infected with the virus eradicate it from their body after 28 days and recover their normal activity. However, a large fraction (~40%) of the people who are infected with the virus suffer from various symptoms (anosmia and/or ageusia, fatigue, cough, myalgia, cognitive impairment, insomnia, dyspnea, and tachycardia) beyond 12 weeks and are diagnosed with a syndrome called long COVID. Long-term clinical studies in a group of people who contracted SARS-CoV-2 have been contrasted with a noninfected matched group of people. A subset of infected people can be distinguished by a set of cytokine markers to have persistent, low-grade inflammation and often self-report two or more bothersome symptoms. No medication can alleviate their symptoms efficiently. Coronavirus nucleocapsid proteins have been investigated extensively as potential drug targets due to their key roles in virus replication, among which is their ability to bind their respective genomic RNAs for incorporation into emerging virions. This review highlights basic studies of the nucleocapsid protein and its ability to undergo liquid-liquid phase separation. We hypothesize that this ability of the nucleocapsid protein for phase separation may contribute to long COVID. This hypothesis unlocks new investigation angles and could potentially open novel avenues for a better understanding of long COVID and treating this condition.
Collapse
Affiliation(s)
- Ahmed Eltayeb
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Faisal Al-Sarraj
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mona Alharbi
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Raed Albiheyri
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
- Centre of Excellence in Bionanoscience Research, King Abdulaziz University, Jeddah, Saudi Arabia
- Immunology Unit, King Fahad Medical Research Centre, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ehab H Mattar
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Isam M Abu Zeid
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Thamer A Bouback
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Atif Bamagoos
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Vladimir N Uversky
- Department of Molecular Medicine and USF Health Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
- Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Moscow Region, Russia
| | - Alberto Rubio-Casillas
- Autlan Regional Hospital, Health Secretariat, Autlan, Jalisco, Mexico
- Biology Laboratory, Autlan Regional Preparatory School, University of Guadalajara, Autlan, Jalisco, Mexico
| | - Elrashdy M Redwan
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
- Centre of Excellence in Bionanoscience Research, King Abdulaziz University, Jeddah, Saudi Arabia
| |
Collapse
|
7
|
Tomaszewski A, Wang R, Sandoval E, Zhu J, Liu J, Li R. Solid-to-liquid phase transition in the dissolution of cytosolic misfolded-protein aggregates. iScience 2023; 26:108334. [PMID: 38025775 PMCID: PMC10663836 DOI: 10.1016/j.isci.2023.108334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 09/08/2023] [Accepted: 10/22/2023] [Indexed: 12/01/2023] Open
Abstract
Accumulation of protein aggregates is a hallmark of cellular aging and degenerative disorders. This could result from either increased protein misfolding and aggregation or impaired dissolution of aggregates formed under stress, the latter of which is poorly understood. In this study, we employed quantitative live-cell imaging to investigate the dynamic process of protein disaggregation in yeast. We show that protein aggregates formed upon heat stress are solid condensates, but after stress attenuation these protein aggregates first transition into a liquid-like state during their dissolution. This solid-to-liquid phase transition (SLPT) accompanies the reduction in aggregate number due to the fusion of the liquid condensates. The chaperone activity of Hsp104, a Clp/HSP100 family chaperone, is required for both SLPT and subsequent dispersal of the liquid condensates. Sse1, a yeast HSP110 chaperone, also facilitates SLPT. These results illuminate an unexpected mechanistic framework of cellular control over protein disaggregation upon stress attenuation.
Collapse
Affiliation(s)
- Alexis Tomaszewski
- Center for Cell Dynamics and Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Biochemistry, Cellular and Molecular Biology (BCMB) Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Rebecca Wang
- Hackensack Meridian School of Medicine, Nutley, NJ 07110, USA
| | - Eduardo Sandoval
- Department of Neuroscience, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jin Zhu
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Jian Liu
- Center for Cell Dynamics and Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Biochemistry, Cellular and Molecular Biology (BCMB) Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Rong Li
- Center for Cell Dynamics and Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Biochemistry, Cellular and Molecular Biology (BCMB) Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
- Department of Biological Science, National University of Singapore, Singapore 117411, Singapore
| |
Collapse
|
8
|
Ciccarelli M, Masser AE, Kaimal JM, Planells J, Andréasson C. Genetic inactivation of essential HSF1 reveals an isolated transcriptional stress response selectively induced by protein misfolding. Mol Biol Cell 2023; 34:ar101. [PMID: 37467033 PMCID: PMC10551698 DOI: 10.1091/mbc.e23-05-0153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/06/2023] [Accepted: 07/12/2023] [Indexed: 07/20/2023] Open
Abstract
Heat Shock Factor 1 (Hsf1) in yeast drives the basal transcription of key proteostasis factors and its activity is induced as part of the core heat shock response. Exploring Hsf1 specific functions has been challenging due to the essential nature of the HSF1 gene and the extensive overlap of target promoters with environmental stress response (ESR) transcription factors Msn2 and Msn4 (Msn2/4). In this study, we constructed a viable hsf1∆ strain by replacing the HSF1 open reading frame with genes that constitutively express Hsp40, Hsp70, and Hsp90 from Hsf1-independent promoters. Phenotypic analysis showed that the hsf1∆ strain grows slowly, is sensitive to heat as well as protein misfolding and accumulates protein aggregates. Transcriptome analysis revealed that the transcriptional response to protein misfolding induced by azetidine-2-carboxylic acid is fully dependent on Hsf1. In contrast, the hsf1∆ strain responded to heat shock through the ESR. Following HS, Hsf1 and Msn2/4 showed functional compensatory induction with stronger activation of the remaining stress pathway when the other branch was inactivated. Thus, we provide a long-overdue genetic test of the function of Hsf1 in yeast using the novel hsf1∆ construct. Our data highlight that the accumulation of misfolded proteins is uniquely sensed by Hsf1-Hsp70 chaperone titration inducing a highly selective transcriptional stress response.
Collapse
Affiliation(s)
- Michela Ciccarelli
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-10691 Stockholm, Sweden
| | - Anna E Masser
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-10691 Stockholm, Sweden
| | | | - Jordi Planells
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-10691 Stockholm, Sweden
| | - Claes Andréasson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-10691 Stockholm, Sweden
| |
Collapse
|
9
|
Metzger MB, Scales JL, Grant GA, Molnar AE, Loncarek J, Weissman AM. Differential sensitivity of the yeast Lon protease Pim1p to impaired mitochondrial respiration. J Biol Chem 2023; 299:104937. [PMID: 37331598 PMCID: PMC10359500 DOI: 10.1016/j.jbc.2023.104937] [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: 03/31/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/20/2023] Open
Abstract
Mitochondria are essential organelles whose proteome is well protected by regulated protein degradation and quality control. While the ubiquitin-proteasome system can monitor mitochondrial proteins that reside at the mitochondrial outer membrane or are not successfully imported, resident proteases generally act on proteins within mitochondria. Herein, we assess the degradative pathways for mutant forms of three mitochondrial matrix proteins (mas1-1HA, mas2-11HA, and tim44-8HA) in Saccharomyces cerevisiae. The degradation of these proteins is strongly impaired by loss of either the matrix AAA-ATPase (m-AAA) (Afg3p/Yta12p) or Lon (Pim1p) protease. We determine that these mutant proteins are all bona fide Pim1p substrates whose degradation is also blocked in respiratory-deficient "petite" yeast cells, such as in cells lacking m-AAA protease subunits. In contrast, matrix proteins that are substrates of the m-AAA protease are not affected by loss of respiration. The failure to efficiently remove Pim1p substrates in petite cells has no evident relationship to Pim1p maturation, localization, or assembly. However, Pim1p's autoproteolysis is intact, and its overexpression restores substrate degradation, indicating that Pim1p retains some functionality in petite cells. Interestingly, chemical perturbation of mitochondria with oligomycin similarly prevents degradation of Pim1p substrates. Our results demonstrate that Pim1p activity is highly sensitive to mitochondrial perturbations such as loss of respiration or drug treatment in a manner that we do not observe with other proteases.
Collapse
Affiliation(s)
- Meredith B Metzger
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA.
| | - Jessica L Scales
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Garis A Grant
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Abigail E Molnar
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Jadranka Loncarek
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Allan M Weissman
- Cancer Innovation Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA.
| |
Collapse
|
10
|
Xie Y, Liu T, Gresham D, Holt LJ. mRNA condensation fluidizes the cytoplasm. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.30.542963. [PMID: 37398029 PMCID: PMC10312499 DOI: 10.1101/2023.05.30.542963] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The intracellular environment is packed with macromolecules of mesoscale size, and this crowded milieu significantly influences cell physiology. When exposed to stress, mRNAs released after translational arrest condense with RNA binding proteins, resulting in the formation of membraneless RNA protein (RNP) condensates known as processing bodies (P-bodies) and stress granules (SGs). However, the impact of the assembly of these condensates on the biophysical properties of the crowded cytoplasmic environment remains unclear. Here, we find that upon exposure to stress, polysome collapse and condensation of mRNAs increases mesoscale particle diffusivity in the cytoplasm. Increased mesoscale diffusivity is required for the efficient formation of Q-bodies, membraneless organelles that coordinate degradation of misfolded peptides that accumulate during stress. Additionally, we demonstrate that polysome collapse and stress granule formation has a similar effect in mammalian cells, fluidizing the cytoplasm at the mesoscale. We find that synthetic, light-induced RNA condensation is sufficient to fluidize the cytoplasm, demonstrating a causal effect of RNA condensation. Together, our work reveals a new functional role for stress-induced translation inhibition and formation of RNP condensates in modulating the physical properties of the cytoplasm to effectively respond to stressful conditions.
Collapse
Affiliation(s)
- Ying Xie
- Institute for Systems Genetics, New York University Langone Medical Center, New York, New York, United States
- Department of Biology, New York University, New York, New York, United States
| | - Tiewei Liu
- Institute for Systems Genetics, New York University Langone Medical Center, New York, New York, United States
| | - David Gresham
- Department of Biology, New York University, New York, New York, United States
| | - Liam J Holt
- Institute for Systems Genetics, New York University Langone Medical Center, New York, New York, United States
| |
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
Uvdal P, Shashkova S. The Effect of Calorie Restriction on Protein Quality Control in Yeast. Biomolecules 2023; 13:biom13050841. [PMID: 37238710 DOI: 10.3390/biom13050841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/30/2023] [Accepted: 05/01/2023] [Indexed: 05/28/2023] Open
Abstract
Initially, protein aggregates were regarded as a sign of a pathological state of the cell. Later, it was found that these assemblies are formed in response to stress, and that some of them serve as signalling mechanisms. This review has a particular focus on how intracellular protein aggregates are related to altered metabolism caused by different glucose concentrations in the extracellular environment. We summarise the current knowledge of the role of energy homeostasis signalling pathways in the consequent effect on intracellular protein aggregate accumulation and removal. This covers regulation at different levels, including elevated protein degradation and proteasome activity mediated by the Hxk2 protein, the enhanced ubiquitination of aberrant proteins through Torc1/Sch9 and Msn2/Whi2, and the activation of autophagy mediated through ATG genes. Finally, certain proteins form reversible biomolecular aggregates in response to stress and reduced glucose levels, which are used as a signalling mechanism in the cell, controlling major primary energy pathways related to glucose sensing.
Collapse
Affiliation(s)
- Petter Uvdal
- Department of Physics, University of Gothenburg, 405 30 Göteborg, Sweden
| | | |
Collapse
|
13
|
Fischbach A, Johns A, Schneider KL, Hao X, Tessarz P, Nyström T. Artificial Hsp104-mediated systems for re-localizing protein aggregates. Nat Commun 2023; 14:2663. [PMID: 37160881 PMCID: PMC10169802 DOI: 10.1038/s41467-023-37706-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 03/28/2023] [Indexed: 05/11/2023] Open
Abstract
Spatial Protein Quality Control (sPQC) sequesters misfolded proteins into specific, organelle-associated inclusions within the cell to control their toxicity. To approach the role of sPQC in cellular fitness, neurodegenerative diseases and aging, we report on the construction of Hsp100-based systems in budding yeast cells, which can artificially target protein aggregates to non-canonical locations. We demonstrate that aggregates of mutant huntingtin (mHtt), the disease-causing agent of Huntington's disease can be artificially targeted to daughter cells as well as to eisosomes and endosomes with this approach. We find that the artificial removal of mHtt inclusions from mother cells protects them from cell death suggesting that even large mHtt inclusions may be cytotoxic, a trait that has been widely debated. In contrast, removing inclusions of endogenous age-associated misfolded proteins does not significantly affect the lifespan of mother cells. We demonstrate also that this approach is able to manipulate mHtt inclusion formation in human cells and has the potential to be useful as an alternative, complementary approach to study the role of sPQC, for example in aging and neurodegenerative disease.
Collapse
Affiliation(s)
- Arthur Fischbach
- Institute for Biomedicine, Sahlgrenska Academy, Centre for Ageing and Health-AgeCap, University of Gothenburg, Gothenburg, Sweden.
- Max-Planck Research Group Chromatin and Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany.
| | - Angela Johns
- Institute for Biomedicine, Sahlgrenska Academy, Centre for Ageing and Health-AgeCap, University of Gothenburg, Gothenburg, Sweden
| | - Kara L Schneider
- Institute for Biomedicine, Sahlgrenska Academy, Centre for Ageing and Health-AgeCap, University of Gothenburg, Gothenburg, Sweden
| | - Xinxin Hao
- Institute for Biomedicine, Sahlgrenska Academy, Centre for Ageing and Health-AgeCap, University of Gothenburg, Gothenburg, Sweden
| | - Peter Tessarz
- Max-Planck Research Group Chromatin and Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany
- Cologne Excellence Cluster on Stress Responses in Ageing-Associated Diseases (CECAD), Cologne, Germany
| | - Thomas Nyström
- Institute for Biomedicine, Sahlgrenska Academy, Centre for Ageing and Health-AgeCap, University of Gothenburg, Gothenburg, Sweden.
| |
Collapse
|
14
|
Hutchinson KM, Hunn JC, Reines D. Nab3 nuclear granule accumulation is driven by respiratory capacity. Curr Genet 2022; 68:581-591. [PMID: 35922525 PMCID: PMC9887517 DOI: 10.1007/s00294-022-01248-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 02/02/2023]
Abstract
Numerous biological processes involve proteins capable of transiently assembling into subcellular compartments necessary for cellular functions. One process is the RNA polymerase II transcription cycle which involves initiation, elongation, co-transcriptional modification of nascent RNA, and termination. The essential yeast transcription termination factor Nab3 is required for termination of small non-coding RNAs and accumulates into a compact nuclear granule upon glucose removal. Nab3 nuclear granule accumulation varies in penetrance across yeast strains and a higher Nab3 granule accumulation phenotype is associated with petite strains, suggesting a possible ATP-dependent mechanism for granule disassembly. Here, we demonstrate the uncoupling of mitochondrial oxidative phosphorylation by drug treatment or deletions of nuclear-encoded ATP synthase subunit genes were sufficient to increase Nab3 granule accumulation and led to an inability to proliferate during prolonged glucose deprivation, which requires respiration. Additionally, by enriching for respiration competent cells from a petite-prone strain, we generated a low granule-accumulating strain from a relatively high one, providing another link between respiratory competency and Nab3 granules. Consistent with the resulting idea that ATP is involved in granule accumulation, the addition of extracellular ATP to semi-permeabilized cells was sufficient to reduce Nab3 granule accumulation. Deleting the SKY1 gene, which encodes a kinase that phosphorylates nuclear SR repeat-containing proteins and is involved in efficient stress granule disassembly, also resulted in increased granule accumulation. This observation implicates Sky1 in Nab3 granule biogenesis. Taken together, these findings suggest there is normally an equilibrium between termination factor granule assembly and disassembly mediated by ATP-requiring nuclear machinery.
Collapse
Affiliation(s)
| | - Jeremy C Hunn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA
| | - Daniel Reines
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, USA.
| |
Collapse
|
15
|
Furutani N, Izawa S. Adaptability of wine yeast to ethanol-induced protein denaturation. FEMS Yeast Res 2022; 22:6831633. [PMID: 36385376 DOI: 10.1093/femsyr/foac059] [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: 08/31/2022] [Revised: 10/28/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022] Open
Abstract
This year marks the 200th anniversary of the birth of Dr Louis Pasteur (1822-1895), who revealed that alcoholic fermentation is performed by yeast cells. Subsequently, details of the mechanisms of alcoholic fermentation and glycolysis in yeast cells have been elucidated. However, the mechanisms underlying the high tolerance and adaptability of yeast cells to ethanol are not yet fully understood. This review presents the response and adaptability of yeast cells to ethanol-induced protein denaturation. Herein, we describe the adverse effects of severe ethanol stress on intracellular proteins and the responses of yeast cells. Furthermore, recent findings on the acquired resistance of wine yeast cells to severe ethanol stress that causes protein denaturation are discussed, not only under laboratory conditions, but also during the fermentation process at 15°C to mimic the vinification process of white wine.
Collapse
Affiliation(s)
- Noboru Furutani
- Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan
| | - Shingo Izawa
- Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan
| |
Collapse
|
16
|
Differential contributions of the proteasome, autophagy, and chaperones to the clearance of arsenite-induced protein aggregates in yeast. J Biol Chem 2022; 298:102680. [PMID: 36356902 PMCID: PMC9723941 DOI: 10.1016/j.jbc.2022.102680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 10/27/2022] [Accepted: 10/31/2022] [Indexed: 11/09/2022] Open
Abstract
The poisonous metalloid arsenite induces widespread misfolding and aggregation of nascent proteins in vivo, and this mode of toxic action might underlie its suspected role in the pathology of certain protein misfolding diseases. Evolutionarily conserved protein quality-control systems protect cells against arsenite-mediated proteotoxicity, and herein, we systematically assessed the contribution of the ubiquitin-proteasome system, the autophagy-vacuole pathway, and chaperone-mediated disaggregation to the clearance of arsenite-induced protein aggregates in Saccharomyces cerevisiae. We show that the ubiquitin-proteasome system is the main pathway that clears aggregates formed during arsenite stress and that cells depend on this pathway for optimal growth. The autophagy-vacuole pathway and chaperone-mediated disaggregation both contribute to clearance, but their roles appear less prominent than the ubiquitin-proteasome system. Our in vitro assays with purified components of the yeast disaggregating machinery demonstrated that chaperone binding to aggregates formed in the presence of arsenite is impaired. Hsp104 and Hsp70 chaperone activity was unaffected by arsenite, suggesting that this metalloid influences aggregate structure, making them less accessible for chaperone-mediated disaggregation. We further show that the defect in chaperone-mediated refolding of a model protein was abrogated in a cysteine-free version of the substrate, suggesting that arsenite directly modifies cysteines in non-native target proteins. In conclusion, our study sheds novel light on the differential contributions of protein quality-control systems to aggregate clearance and cell proliferation and extends our understanding of how these systems operate during arsenite stress.
Collapse
|
17
|
Identification of Genes Promoting Growth of Ustilago maydis on Biomolecules Released from Cells Killed by Oxidation. J Fungi (Basel) 2022; 8:jof8090957. [PMID: 36135682 PMCID: PMC9503528 DOI: 10.3390/jof8090957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/07/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
Much headway has been made in understanding the numerous strategies that enable microorganisms to counteract various types of environmental stress, but little is known about how microbial populations recover after a massive death caused by exposure to extreme conditions. Using the yeast-like fungus Ustilago maydis as a model, our recent post-stress regrowth under starvation (RUS) studies have demonstrated that this organism reconstitutes devastated populations with remarkable efficiency. Subsequently, we have identified four RUS-gene products. Two of these, Did4 and Tbp1, play parallel roles in protecting the genome. To identify additional molecular components, we took a molecular-genetic and a transcriptomic approach. By employing a simple and novel screening method, we identified five RUS-deficient mutants (snf8, slm1, vrg4, snf5, hsf1), three of which (snf8, slm1, and hsf1) displayed sensitivity to different genotoxic agents, indicating that the corresponding gene products have roles in genome protection. The global transcriptomic changes of cells grown in supernatants derived from peroxide-treated cell suspensions revealed sets of uniquely expressed genes. Importantly, among the genes induced by the substrates was Chk1, which encodes a protein kinase required for checkpoint-mediated cell cycle arrest in response to DNA damage. Mutants of U. maydis deleted of Chk1 are severely incapacitated in RUS.
Collapse
|
18
|
Loh D, Reiter RJ. Melatonin: Regulation of Viral Phase Separation and Epitranscriptomics in Post-Acute Sequelae of COVID-19. Int J Mol Sci 2022; 23:8122. [PMID: 35897696 PMCID: PMC9368024 DOI: 10.3390/ijms23158122] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/09/2022] [Accepted: 07/20/2022] [Indexed: 01/27/2023] Open
Abstract
The relentless, protracted evolution of the SARS-CoV-2 virus imposes tremendous pressure on herd immunity and demands versatile adaptations by the human host genome to counter transcriptomic and epitranscriptomic alterations associated with a wide range of short- and long-term manifestations during acute infection and post-acute recovery, respectively. To promote viral replication during active infection and viral persistence, the SARS-CoV-2 envelope protein regulates host cell microenvironment including pH and ion concentrations to maintain a high oxidative environment that supports template switching, causing extensive mitochondrial damage and activation of pro-inflammatory cytokine signaling cascades. Oxidative stress and mitochondrial distress induce dynamic changes to both the host and viral RNA m6A methylome, and can trigger the derepression of long interspersed nuclear element 1 (LINE1), resulting in global hypomethylation, epigenetic changes, and genomic instability. The timely application of melatonin during early infection enhances host innate antiviral immune responses by preventing the formation of "viral factories" by nucleocapsid liquid-liquid phase separation that effectively blockades viral genome transcription and packaging, the disassembly of stress granules, and the sequestration of DEAD-box RNA helicases, including DDX3X, vital to immune signaling. Melatonin prevents membrane depolarization and protects cristae morphology to suppress glycolysis via antioxidant-dependent and -independent mechanisms. By restraining the derepression of LINE1 via multifaceted strategies, and maintaining the balance in m6A RNA modifications, melatonin could be the quintessential ancient molecule that significantly influences the outcome of the constant struggle between virus and host to gain transcriptomic and epitranscriptomic dominance over the host genome during acute infection and PASC.
Collapse
Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA;
| | - Russel J. Reiter
- Department of Cell Systems and Anatomy, UT Health San Antonio, San Antonio, TX 78229, USA
| |
Collapse
|
19
|
Vanderwaeren L, Dok R, Voordeckers K, Vandemaele L, Verstrepen KJ, Nuyts S. An Integrated Approach Reveals DNA Damage and Proteotoxic Stress as Main Effects of Proton Radiation in S. cerevisiae. Int J Mol Sci 2022; 23:ijms23105493. [PMID: 35628303 PMCID: PMC9145671 DOI: 10.3390/ijms23105493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/09/2022] [Accepted: 05/12/2022] [Indexed: 02/01/2023] Open
Abstract
Proton radiotherapy (PRT) has the potential to reduce the normal tissue toxicity associated with conventional photon-based radiotherapy (X-ray therapy, XRT) because the active dose can be more directly targeted to a tumor. Although this dosimetric advantage of PRT is well known, the molecular mechanisms affected by PRT remain largely elusive. Here, we combined the molecular toolbox of the eukaryotic model Saccharomyces cerevisiae with a systems biology approach to investigate the physiological effects of PRT compared to XRT. Our data show that the DNA damage response and protein stress response are the major molecular mechanisms activated after both PRT and XRT. However, RNA-Seq revealed that PRT treatment evoked a stronger activation of genes involved in the response to proteotoxic stress, highlighting the molecular differences between PRT and XRT. Moreover, inhibition of the proteasome resulted in decreased survival in combination with PRT compared to XRT, not only further confirming that protons induced a stronger proteotoxic stress response, but also hinting at the potential of using proteasome inhibitors in combination with proton radiotherapy in clinical settings.
Collapse
Affiliation(s)
- Laura Vanderwaeren
- Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven, 3000 Leuven, Belgium; (L.V.); (R.D.); (L.V.)
- Laboratory of Genetics and Genomics, Centre for Microbial and Plant Genetics, KU Leuven, 3000 Leuven, Belgium;
- Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, 3000 Leuven, Belgium
| | - Rüveyda Dok
- Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven, 3000 Leuven, Belgium; (L.V.); (R.D.); (L.V.)
| | - Karin Voordeckers
- Laboratory of Genetics and Genomics, Centre for Microbial and Plant Genetics, KU Leuven, 3000 Leuven, Belgium;
- Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, 3000 Leuven, Belgium
| | - Laura Vandemaele
- Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven, 3000 Leuven, Belgium; (L.V.); (R.D.); (L.V.)
- Laboratory of Genetics and Genomics, Centre for Microbial and Plant Genetics, KU Leuven, 3000 Leuven, Belgium;
- Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, 3000 Leuven, Belgium
| | - Kevin J. Verstrepen
- Laboratory of Genetics and Genomics, Centre for Microbial and Plant Genetics, KU Leuven, 3000 Leuven, Belgium;
- Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, 3000 Leuven, Belgium
- Correspondence: (K.J.V.); (S.N.); Tel.: +32-(0)16-75-1393 (K.J.V.); +32-1634-7600 (S.N.); Fax: +32-1634-7623 (S.N.)
| | - Sandra Nuyts
- Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven, 3000 Leuven, Belgium; (L.V.); (R.D.); (L.V.)
- Department of Radiation Oncology, Leuven Cancer Institute, University Hospitals Leuven, 3000 Leuven, Belgium
- Correspondence: (K.J.V.); (S.N.); Tel.: +32-(0)16-75-1393 (K.J.V.); +32-1634-7600 (S.N.); Fax: +32-1634-7623 (S.N.)
| |
Collapse
|
20
|
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.
Collapse
|
21
|
Variable penetrance of Nab3 granule accumulation quantified by a new tool for high-throughput single-cell granule analysis. Curr Genet 2022; 68:467-480. [PMID: 35301575 DOI: 10.1007/s00294-022-01234-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/16/2022] [Accepted: 03/02/2022] [Indexed: 12/12/2022]
Abstract
Reorganization of cellular proteins into subcellular compartments, such as the concentration of RNA-binding proteins into cytoplasmic stress granules and P-bodies, is a well-recognized, widely studied physiological process currently under intense investigation. One example of this is the induction of the yeast Nab3 transcription termination factor to rearrange from its pan-nucleoplasmic distribution to a granule at the nuclear periphery in response to nutrient limitation. Recent work in many cell types has shown that protein condensation in the nucleus is functionally important for transcription initiation, RNA processing, and termination. However, little is known about how subnuclear compartments form. Here, we have quantitatively analyzed this dynamic process in living yeast using a high-throughput computational tool and fluorescence microscopy. This analysis revealed that Nab3 granule accumulation varies in penetrance across yeast strains. A concentrated single granule is formed from at least a quarter of the nuclear Nab3 drawn from the rest of the nucleus. Levels of granule accumulation were inversely correlated with a growth defect in the absence of glucose. Importantly, the basis for some of the variation in penetrance was attributable to a defect in mitochondrial function. This publicly available computational tool provides a rigorous, reproducible, and unbiased examination of Nab3 granule accumulation that should be widely applicable to a variety of fluorescent images. Thousands of live cells can be readily examined enabling rigorous statistical verification of significance. With it, we describe a new feature of inducible subnuclear compartment formation for RNA-binding transcription factors and an important determinant of granule biogenesis.
Collapse
|
22
|
The Effect of Lithium on the Budding Yeast Saccharomyces cerevisiae upon Stress Adaptation. Microorganisms 2022; 10:microorganisms10030590. [PMID: 35336166 PMCID: PMC8953283 DOI: 10.3390/microorganisms10030590] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/02/2022] [Accepted: 03/07/2022] [Indexed: 02/05/2023] Open
Abstract
Lithium salts are used in the treatment of mood disorders, cancer, and Alzheimer's disease. It has been shown to prolong life span in several phyla; however, not yet in budding yeast. In our study, we investigate the influence of lithium on yeast cells' viability by characterizing protein aggregate formation, cell volume, and molecular crowding in the context of stress adaptation. While our data suggest a concentration-dependent growth inhibition caused by LiCl, we show an extended long-term survival rate as an effect of lithium addition upon glucose deprivation. We show that caloric restriction mitigates the negative impact of LiCl on cellular survival. Therefore, we suggest that lithium could affect glucose metabolism upon caloric restriction, which could explain the extended long-term survival observed in our study. We find furthermore that lithium chloride did not affect an immediate salt-induced Hsp104-dependent aggregate formation but cellular adaptation to H2O2 and acute glucose starvation. We presume that different salt types and concentrations interfere with effective Hsp104 recruitment or its ATP-dependent disaggregase activity as a response to salt stress. This work provides novel details of Li+ effect on live eukaryotic cells which may also be applicable in further research on the treatment of cancer, Alzheimer's, or other age-related diseases in humans.
Collapse
|
23
|
Overexpression of MET4 Leads to the Upregulation of Stress-Related Genes and Enhanced Sulfite Tolerance in Saccharomyces uvarum. Cells 2022; 11:cells11040636. [PMID: 35203287 PMCID: PMC8869826 DOI: 10.3390/cells11040636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 12/10/2022] Open
Abstract
Saccharomyces uvarum is one of the few fermentative species that can be used in winemaking, but its weak sulfite tolerance is the main reason for its further use. Previous studies have shown that the expression of the methionine synthase gene (MET4) is upregulated in FZF1 (a gene encoding a putative zinc finger protein, which is a positive regulator of the transcription of the cytosolic sulfotransferase gene SSU1) overexpression transformant strains, but its exact function is unknown. To gain insight into the function of the MET4 gene, in this study, a MET4 overexpression vector was constructed and transformed into S. uvarum strain A9. The MET4 transformants showed a 20 mM increase in sulfite tolerance compared to the starting strain. Ninety-two differential genes were found in the transcriptome of A9-MET4 compared to the A9 strain, of which 90 were upregulated, and two were downregulated. The results of RT-qPCR analyses confirmed that the expression of the HOMoserine requiring gene (HOM3) in the sulfate assimilation pathway and some fermentation-stress-related genes were upregulated in the transformants. The overexpression of the MET4 gene resulted in a significant increase in sulfite tolerance, the upregulation of fermentation-stress-related gene expression, and significant changes in the transcriptome profile of the S. uvarum strain.
Collapse
|
24
|
Reversible amyloids of pyruvate kinase couple cell metabolism and stress granule disassembly. Nat Cell Biol 2021; 23:1085-1094. [PMID: 34616026 PMCID: PMC7611853 DOI: 10.1038/s41556-021-00760-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 08/23/2021] [Indexed: 11/08/2022]
Abstract
Cells respond to stress by blocking translation, rewiring metabolism and forming transient messenger ribonucleoprotein assemblies called stress granules (SGs). After stress release, re-establishing homeostasis and disassembling SGs requires ATP-consuming processes. However, the molecular mechanisms whereby cells restore ATP production and disassemble SGs after stress remain poorly understood. Here we show that upon stress, the ATP-producing enzyme Cdc19 forms inactive amyloids, and that their rapid re-solubilization is essential to restore ATP production and disassemble SGs in glucose-containing media. Cdc19 re-solubilization is initiated by the glycolytic metabolite fructose-1,6-bisphosphate, which directly binds Cdc19 amyloids, allowing Hsp104 and Ssa2 chaperone recruitment and aggregate re-solubilization. Fructose-1,6-bisphosphate then promotes Cdc19 tetramerization, which boosts its activity to further enhance ATP production and SG disassembly. Together, these results describe a molecular mechanism that is critical for stress recovery and directly couples cellular metabolism with SG dynamics via the regulation of reversible Cdc19 amyloids.
Collapse
|
25
|
Loh D, Reiter RJ. Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders. Antioxidants (Basel) 2021; 10:1483. [PMID: 34573116 PMCID: PMC8465482 DOI: 10.3390/antiox10091483] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022] Open
Abstract
Biomolecular condensates are membraneless organelles (MLOs) that form dynamic, chemically distinct subcellular compartments organizing macromolecules such as proteins, RNA, and DNA in unicellular prokaryotic bacteria and complex eukaryotic cells. Separated from surrounding environments, MLOs in the nucleoplasm, cytoplasm, and mitochondria assemble by liquid-liquid phase separation (LLPS) into transient, non-static, liquid-like droplets that regulate essential molecular functions. LLPS is primarily controlled by post-translational modifications (PTMs) that fine-tune the balance between attractive and repulsive charge states and/or binding motifs of proteins. Aberrant phase separation due to dysregulated membrane lipid rafts and/or PTMs, as well as the absence of adequate hydrotropic small molecules such as ATP, or the presence of specific RNA proteins can cause pathological protein aggregation in neurodegenerative disorders. Melatonin may exert a dominant influence over phase separation in biomolecular condensates by optimizing membrane and MLO interdependent reactions through stabilizing lipid raft domains, reducing line tension, and maintaining negative membrane curvature and fluidity. As a potent antioxidant, melatonin protects cardiolipin and other membrane lipids from peroxidation cascades, supporting protein trafficking, signaling, ion channel activities, and ATPase functionality during condensate coacervation or dissolution. Melatonin may even control condensate LLPS through PTM and balance mRNA- and RNA-binding protein composition by regulating N6-methyladenosine (m6A) modifications. There is currently a lack of pharmaceuticals targeting neurodegenerative disorders via the regulation of phase separation. The potential of melatonin in the modulation of biomolecular condensate in the attenuation of aberrant condensate aggregation in neurodegenerative disorders is discussed in this review.
Collapse
Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX 78229, USA
| |
Collapse
|
26
|
Fernández A. Artificial Intelligence Deconstructs Drug Targeting In Vivo by Leveraging a Transformer Platform. ACS Med Chem Lett 2021; 12:1052-1055. [PMID: 34267868 DOI: 10.1021/acsmedchemlett.1c00237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Lead optimization in structure-based drug design ultimately requires that the therapeutic agent be evaluated in the cellular context. However, the in vivo control of the target structure remains unyielding to computational modeling. This situation may change as transformer technologies enable a deconstruction of in vivo cooperativity steering drug-induced protein folding.
Collapse
Affiliation(s)
- Ariel Fernández
- Daruma Institute for AI in Pharmaceutical Research, AF Innovation Pharma Consultancy, GmbH, 4000 Pemberton Court, Winston-Salem, North Carolina 27106, United States
- CONICET/INQUISUR, National Research Council for Science and Technology, Buenos Aires 1033, Argentina
| |
Collapse
|
27
|
Campos-Melo D, Hawley ZCE, Droppelmann CA, Strong MJ. The Integral Role of RNA in Stress Granule Formation and Function. Front Cell Dev Biol 2021; 9:621779. [PMID: 34095105 PMCID: PMC8173143 DOI: 10.3389/fcell.2021.621779] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/16/2021] [Indexed: 12/12/2022] Open
Abstract
Stress granules (SGs) are phase-separated, membraneless, cytoplasmic ribonucleoprotein (RNP) assemblies whose primary function is to promote cell survival by condensing translationally stalled mRNAs, ribosomal components, translation initiation factors, and RNA-binding proteins (RBPs). While the protein composition and the function of proteins in the compartmentalization and the dynamics of assembly and disassembly of SGs has been a matter of study for several years, the role of RNA in these structures had remained largely unknown. RNA species are, however, not passive members of RNA granules in that RNA by itself can form homo and heterotypic interactions with other RNA molecules leading to phase separation and nucleation of RNA granules. RNA can also function as molecular scaffolds recruiting multivalent RBPs and their interactors to form higher-order structures. With the development of SG purification techniques coupled to RNA-seq, the transcriptomic landscape of SGs is becoming increasingly understood, revealing the enormous potential of RNA to guide the assembly and disassembly of these transient organelles. SGs are not only formed under acute stress conditions but also in response to different diseases such as viral infections, cancer, and neurodegeneration. Importantly, these granules are increasingly being recognized as potential precursors of pathological aggregates in neurodegenerative diseases. In this review, we examine the current evidence in support of RNA playing a significant role in the formation of SGs and explore the concept of SGs as therapeutic targets.
Collapse
Affiliation(s)
- Danae Campos-Melo
- Molecular Medicine Group, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Zachary C E Hawley
- Molecular Medicine Group, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Cristian A Droppelmann
- Molecular Medicine Group, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Michael J Strong
- Molecular Medicine Group, Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Department of Pathology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Department of Clinical Neurological Sciences, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| |
Collapse
|
28
|
Fernández A. Artificial Intelligence Set to Reverse Engineer Drug Targeting in the Cell. ACS Pharmacol Transl Sci 2021; 4:1256-1259. [PMID: 34151218 DOI: 10.1021/acsptsci.1c00107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Indexed: 11/28/2022]
Abstract
Therapeutic drugs are required to target proteins in the cell, not in vitro. Yet, drug-induced protein folding in vivo is off limits to computational modeling efforts. This situation may change as artificial intelligence empowers molecular dynamics and enables the deconstruction of in vivo cooperativity for structural adaptation.
Collapse
Affiliation(s)
- Ariel Fernández
- Daruma Institute for AI in Pharmaceutical Research, AF Innovation Pharma Consultancy, GmbH, 4000 Pemberton Court, Winston-Salem, North Carolina 27106, United States.,CONICET, Argentine National Research Council, Buenos Aires 1033, Argentina
| |
Collapse
|