51
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Park YJ, Choi DW, Cho SW, Han J, Yang S, Choi CY. Stress Granule Formation Attenuates RACK1-Mediated Apoptotic Cell Death Induced by Morusin. Int J Mol Sci 2020; 21:ijms21155360. [PMID: 32731602 PMCID: PMC7432505 DOI: 10.3390/ijms21155360] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 07/26/2020] [Indexed: 12/15/2022] Open
Abstract
Stress granules are membraneless organelles composed of numerous components including ribonucleoproteins. The stress granules are characterized by a dynamic complex assembly in response to various environmental stressors, which has been implicated in the coordinated regulation of diverse biological pathways, to exert a protective role against stress-induced cell death. Here, we show that stress granule formation is induced by morusin, a novel phytochemical displaying antitumor capacity through barely known mechanisms. Morusin-mediated induction of stress granules requires activation of protein kinase R (PKR) and subsequent eIF2α phosphorylation. Notably, genetic inactivation of stress granule formation mediated by G3BP1 knockout sensitized cancer cells to morusin treatment. This protective function against morusin-mediated cell death can be attributed at least in part to the sequestration of receptors for activated C kinase-1 (RACK1) within the stress granules, which reduces caspase-3 activation. Collectively, our study provides biochemical evidence for the role of stress granules in suppressing the antitumor capacity of morusin, proposing that morusin treatment, together with pharmacological inhibition of stress granules, could be an efficient strategy for targeting cancer.
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Affiliation(s)
- Ye-Jin Park
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea; (Y.-J.P.); (D.W.C.); (S.W.C.)
| | - Dong Wook Choi
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea; (Y.-J.P.); (D.W.C.); (S.W.C.)
| | - Sang Woo Cho
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea; (Y.-J.P.); (D.W.C.); (S.W.C.)
| | - Jaeseok Han
- Soonchunhyang Institute of Medi-bio Science (SIMS), Soonchunhyang University, Cheonan, Chungcheongnam-do 31151, Korea;
| | - Siyoung Yang
- Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon 16499, Korea;
| | - Cheol Yong Choi
- Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea; (Y.-J.P.); (D.W.C.); (S.W.C.)
- Correspondence: ; Tel.: +82-31-290-7010; Fax: +82-31-290-7015
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52
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Feng S, Daw JN, Chen QM. Histone deacetylase inhibitors prevent H 2O 2 from inducing stress granule formation. Curr Res Toxicol 2020; 1:141-148. [PMID: 34345843 PMCID: PMC8320627 DOI: 10.1016/j.crtox.2020.10.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/02/2020] [Accepted: 10/20/2020] [Indexed: 12/27/2022] Open
Abstract
Reactive Oxygen Species (ROS) are generated as by-products of aerobic metabolism. The production of ROS increases during xenobiotic stress and under multiple pathological conditions. Although ROS are considered harmful historically, mounting evidence recently indicates a signaling function of ROS, preceding to and regulating transcriptional or post-transcriptional events, contributing to cell death or cell survival and adaptation. Among the cellular defense mechanisms activated by ROS is formation of stress granules (SGs). The stalled translational apparatus, together with mRNA, aggregates into microscopically detectable and molecularly dynamic granules. We found that with H2O2, the dose most potent for inducing SGs in HeLa cells is 400-600 μM. With 200 μM H2O2, 2 h treatment induced the highest percentage of cells containing SGs. Whether ROS signaling pathways regulate the formation of SGs was tested using pharmacological inhibitors. We probed the potential role of PI3K, MAPKs, PKC or histone deacetylation in SG formation. Using deferoxamine as a positive control, we found a lack of inhibitory effect of wortmannin, LY-294002, JNK-I, SB-202190, PD-98059, or H89 when the percentage of cells containing SGs was counted. About 35% inhibition was observed with HDAC6 inhibitor Tubastatin A, whereas general HDAC inhibitor Trichostatin A provided a complete inhibition of SG formation. Our data point to the need of investigating the role of HDACs in SG formation during oxidative stress.
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Affiliation(s)
- Siyuan Feng
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson AZ85721, USA
| | - Jennifer Nichole Daw
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson AZ85721, USA
| | - Qin M. Chen
- Department of Pharmacology, College of Medicine, University of Arizona, 1501 N. Campbell Ave, Tucson AZ85721, USA
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53
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Frydrýšková K, Mašek T, Pospíšek M. Changing faces of stress: Impact of heat and arsenite treatment on the composition of stress granules. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 11:e1596. [PMID: 32362075 DOI: 10.1002/wrna.1596] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 03/19/2020] [Accepted: 03/23/2020] [Indexed: 11/07/2022]
Abstract
Stress granules (SGs), hallmarks of the cellular adaptation to stress, promote survival, conserve cellular energy, and are fully dissolved upon the cessation of stress treatment. Different stresses can initiate the assembly of SGs, but arsenite and heat are the best studied of these stresses. The composition of SGs and posttranslational modifications of SG proteins differ depending on the type and severity of the stress insult, methodology used, cell line, and presence of overexpressed and tagged proteins. A group of 18 proteins showing differential localization to SGs in heat- and arsenite-stressed mammalian cell lines is described. Upon severe and prolonged stress, physiological SGs transform into more solid protein aggregates that are no longer reversible and do not contain mRNA. Similar pathological inclusions are hallmarks of neurodegenerative diseases. SGs induced by heat stress are less dynamic than SGs induced by arsenite and contain a set of unique proteins and linkage-specific polyubiquitinated proteins. The same types of ubiquitin linkages have been found to contribute to the development of neurodegenerative disorders such as Parkinson disease, Alzheimer disease, and amyotrophic lateral sclerosis (ALS). We propose heat stress-induced SGs as a possible model of an intermediate stage along the transition from dynamic, fully reversible arsenite stress-induced SGs toward aberrant SGs, the hallmark of neurodegenerative diseases. Stress- and methodology-specific differences in the compositions of SGs and the transition of SGs to aberrant protein aggregates are discussed. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Export and Localization > RNA Localization.
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Affiliation(s)
| | | | - Martin Pospíšek
- Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czechia
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54
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Amen T, Kaganovich D. Stress granules sense metabolic stress at the plasma membrane and potentiate recovery by storing active Pkc1. Sci Signal 2020; 13:13/623/eaaz6339. [DOI: 10.1126/scisignal.aaz6339] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
As the physical barrier between the cell and the outside environment, the plasma membrane is well-positioned to be the first responder to stress. The membrane is also highly vulnerable to many types of perturbation, including heat, force, osmotic pressure, lipid shortage, and starvation. To determine whether the structural changes in the plasma membrane of Saccharomyces cerevisiae brought about by nutrient stress can be communicated to regulatory networks within the cell, we identified proteins that interact with stress granules (SGs), subcellular structures composed of proteins, and nontranslated RNAs that form when cells are stressed. We found that SG proteins interacted with components of eisosomes, which are subcortical membrane structures with a distinct lipid and protein composition. In response to starvation-triggered phosphorylation of eisosome proteins, eisosomes clustered and recruited SG components, including active Pkc1. The absence of eisosomes impaired SG formation, resulting in delayed recovery from nutrient deprivation. Thus, eisosome clustering is an example of interdomain communication in response to stress and identifies a previously unknown mechanism of SG regulation.
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Affiliation(s)
- Triana Amen
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Daniel Kaganovich
- Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- 1Base Pharmaceuticals, Boston, MA 02129, USA
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55
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Pizzinga M, Harvey RF, Garland GD, Mordue R, Dezi V, Ramakrishna M, Sfakianos A, Monti M, Mulroney TE, Poyry T, Willis AE. The cell stress response: extreme times call for post‐transcriptional measures. WILEY INTERDISCIPLINARY REVIEWS-RNA 2019; 11:e1578. [DOI: 10.1002/wrna.1578] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/09/2019] [Accepted: 10/16/2019] [Indexed: 12/26/2022]
Affiliation(s)
| | | | | | - Ryan Mordue
- MRC Toxicology Unit University of Cambridge Leicester UK
| | - Veronica Dezi
- MRC Toxicology Unit University of Cambridge Leicester UK
| | | | | | - Mie Monti
- MRC Toxicology Unit University of Cambridge Leicester UK
| | | | - Tuija Poyry
- MRC Toxicology Unit University of Cambridge Leicester UK
| | - Anne E. Willis
- MRC Toxicology Unit University of Cambridge Leicester UK
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56
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Anderson CJ, Bredvik K, Burstein SR, Davis C, Meadows SM, Dash J, Case L, Milner TA, Kawamata H, Zuberi A, Piersigilli A, Lutz C, Manfredi G. ALS/FTD mutant CHCHD10 mice reveal a tissue-specific toxic gain-of-function and mitochondrial stress response. Acta Neuropathol 2019; 138:103-121. [PMID: 30877432 DOI: 10.1007/s00401-019-01989-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/25/2019] [Accepted: 03/08/2019] [Indexed: 12/12/2022]
Abstract
Mutations in coiled-coil-helix-coiled-coil-helix domain containing 10 (CHCHD10), a mitochondrial protein of unknown function, cause a disease spectrum with clinical features of motor neuron disease, dementia, myopathy and cardiomyopathy. To investigate the pathogenic mechanisms of CHCHD10, we generated mutant knock-in mice harboring the mouse-equivalent of a disease-associated human S59L mutation, S55L in the endogenous mouse gene. CHCHD10S55L mice develop progressive motor deficits, myopathy, cardiomyopathy and accelerated mortality. Critically, CHCHD10 accumulates in aggregates with its paralog CHCHD2 specifically in affected tissues of CHCHD10S55L mice, leading to aberrant organelle morphology and function. Aggregates induce a potent mitochondrial integrated stress response (mtISR) through mTORC1 activation, with elevation of stress-induced transcription factors, secretion of myokines, upregulated serine and one-carbon metabolism, and downregulation of respiratory chain enzymes. Conversely, CHCHD10 ablation does not induce disease pathology or activate the mtISR, indicating that CHCHD10S55L-dependent disease pathology is not caused by loss-of-function. Overall, CHCHD10S55L mice recapitulate crucial aspects of human disease and reveal a novel toxic gain-of-function mechanism through maladaptive mtISR and metabolic dysregulation.
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57
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Ahmed K, Carter DE, Lajoie P. Hyperactive
TORC
1 sensitizes yeast cells to endoplasmic reticulum stress by compromising cell wall integrity. FEBS Lett 2019; 593:1957-1973. [DOI: 10.1002/1873-3468.13463] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 05/17/2019] [Indexed: 12/20/2022]
Affiliation(s)
- Khadija Ahmed
- Department of Anatomy and Cell Biology The University of Western Ontario London Canada
| | - David E. Carter
- Robarts Research Institute The University of Western Ontario London Canada
| | - Patrick Lajoie
- Department of Anatomy and Cell Biology The University of Western Ontario London Canada
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58
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Das F, Maity S, Ghosh-Choudhury N, Kasinath BS, Ghosh Choudhury G. Deacetylation of S6 kinase promotes high glucose-induced glomerular mesangial cell hypertrophy and matrix protein accumulation. J Biol Chem 2019; 294:9440-9460. [PMID: 31028173 DOI: 10.1074/jbc.ra118.007023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/09/2019] [Indexed: 12/30/2022] Open
Abstract
S6 kinase acts as a driver for renal hypertrophy and matrix accumulation, two key pathologic signatures of diabetic nephropathy. As a post-translational modification, S6 kinase undergoes acetylation at the C terminus. The role of this acetylation to regulate kidney glomerular cell hypertrophy and matrix expansion is not known. In mesangial cells, high glucose decreased the acetylation and enhanced phosphorylation of S6 kinase and its substrates rps6 and eEF2 kinase that lead to dephosphorylation of eEF2. To determine the mechanism of S6 kinase deacetylation, we found that trichostatin A, a pan-histone deacetylase (HDAC) inhibitor, blocked all high glucose-induced effects. Furthermore, high glucose increased the expression and association of HDAC1 with S6 kinase. HDAC1 decreased the acetylation of S6 kinase and mimicked the effects of high glucose, resulting in mesangial cell hypertrophy and expression of fibronectin and collagen I (α2). In contrast, siRNA against HDAC1 inhibited these effects by high glucose. A C-terminal acetylation-mimetic mutant of S6 kinase suppressed high glucose-stimulated phosphorylation of S6 kinase, rps6 and eEF2 kinase, and inhibited the dephosphorylation of eEF2. Also, the acetylation mimetic attenuated the mesangial cell hypertrophy and fibronectin and collagen I (α2) expression. Conversely, an S6 kinase acetylation-deficient mutant induced all the above effects of high glucose. Finally, in the renal glomeruli of diabetic rats, the acetylation of S6 kinase was significantly reduced concomitant with increased HDAC1 and S6 kinase activity. In aggregate, our data uncovered a previously unrecognized role of S6 kinase deacetylation in high glucose-induced mesangial cell hypertrophy and matrix protein expression.
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Affiliation(s)
| | | | | | | | - Goutam Ghosh Choudhury
- Departments of Medicine and .,Departments of Medicine and.,Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas 78229 and
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59
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Heberle AM, Razquin Navas P, Langelaar-Makkinje M, Kasack K, Sadik A, Faessler E, Hahn U, Marx-Stoelting P, Opitz CA, Sers C, Heiland I, Schäuble S, Thedieck K. The PI3K and MAPK/p38 pathways control stress granule assembly in a hierarchical manner. Life Sci Alliance 2019; 2:2/2/e201800257. [PMID: 30923191 PMCID: PMC6441495 DOI: 10.26508/lsa.201800257] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 03/06/2019] [Accepted: 03/07/2019] [Indexed: 01/11/2023] Open
Abstract
PI3K and p38 act in a hierarchical manner to enhance mTORC1 activity and stress granule formation; although PI3K is the main driver, the impact of p38 gets apparent as PI3K activity declines. All cells and organisms exhibit stress-coping mechanisms to ensure survival. Cytoplasmic protein-RNA assemblies termed stress granules are increasingly recognized to promote cellular survival under stress. Thus, they might represent tumor vulnerabilities that are currently poorly explored. The translation-inhibitory eIF2α kinases are established as main drivers of stress granule assembly. Using a systems approach, we identify the translation enhancers PI3K and MAPK/p38 as pro-stress-granule-kinases. They act through the metabolic master regulator mammalian target of rapamycin complex 1 (mTORC1) to promote stress granule assembly. When highly active, PI3K is the main driver of stress granules; however, the impact of p38 becomes apparent as PI3K activity declines. PI3K and p38 thus act in a hierarchical manner to drive mTORC1 activity and stress granule assembly. Of note, this signaling hierarchy is also present in human breast cancer tissue. Importantly, only the recognition of the PI3K-p38 hierarchy under stress enabled the discovery of p38’s role in stress granule formation. In summary, we assign a new pro-survival function to the key oncogenic kinases PI3K and p38, as they hierarchically promote stress granule formation.
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Affiliation(s)
- Alexander Martin Heberle
- Laboratory of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Patricia Razquin Navas
- Laboratory of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Miriam Langelaar-Makkinje
- Laboratory of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Katharina Kasack
- Laboratory of Molecular Tumor Pathology, Institute of Pathology, Charité Universitätsmedizin Berlin, Berlin, Germany.,German Cancer Consortium (DKTK), Partner Site Berlin, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Ahmed Sadik
- Brain Cancer Metabolism Group, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), Heidelberg, Germany.,Faculty of Bioscience, Heidelberg University, Heidelberg, Germany
| | - Erik Faessler
- Jena University Language and Information Engineering Lab, Friedrich-Schiller-University Jena, Jena, Germany
| | - Udo Hahn
- Jena University Language and Information Engineering Lab, Friedrich-Schiller-University Jena, Jena, Germany
| | - Philip Marx-Stoelting
- German Federal Institute for Risk Assessment, Strategies for Toxicological Assessment, Experimental Toxicology and ZEBET, German Centre for the Protection of Laboratory Animals (Bf3R), Berlin, Germany
| | - Christiane A Opitz
- Brain Cancer Metabolism Group, German Cancer Research Center (DKFZ), German Cancer Consortium (DKTK), Heidelberg, Germany.,Neurology Clinic and National Center for Tumor Diseases, University Hospital of Heidelberg, Heidelberg, Germany
| | - Christine Sers
- Laboratory of Molecular Tumor Pathology, Institute of Pathology, Charité Universitätsmedizin Berlin, Berlin, Germany.,German Cancer Consortium (DKTK), Partner Site Berlin, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Ines Heiland
- Faculty of Bioscience, Fisheries and Economics, Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Sascha Schäuble
- Jena University Language and Information Engineering Lab, Friedrich-Schiller-University Jena, Jena, Germany .,Systems Biology and Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
| | - Kathrin Thedieck
- Laboratory of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands .,Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
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60
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Hofweber M, Dormann D. Friend or foe-Post-translational modifications as regulators of phase separation and RNP granule dynamics. J Biol Chem 2018; 294:7137-7150. [PMID: 30587571 DOI: 10.1074/jbc.tm118.001189] [Citation(s) in RCA: 235] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Ribonucleoprotein (RNP) granules are membrane-less organelles consisting of RNA-binding proteins (RBPs) and RNA. RNA granules form through liquid-liquid phase separation (LLPS), whereby weak promiscuous interactions among RBPs and/or RNAs create a dense network of interacting macromolecules and drive the phase separation. Post-translational modifications (PTMs) of RBPs have emerged as important regulators of LLPS and RNP granule dynamics, as they can directly weaken or enhance the multivalent interactions between phase-separating macromolecules or can recruit or exclude certain macromolecules into or from condensates. Here, we review recent insights into how PTMs regulate phase separation and RNP granule dynamics, in particular arginine (Arg)-methylation and phosphorylation. We discuss how these PTMs regulate the phase behavior of prototypical RBPs and how, as "friend or foe," they might influence the assembly, disassembly, or material properties of cellular RNP granules, such as stress granules or amyloid-like condensates. We particularly highlight how PTMs control the phase separation and aggregation behavior of disease-linked RBPs. We also review how disruptions of PTMs might be involved in aberrant phase transitions and the formation of amyloid-like protein aggregates as observed in neurodegenerative diseases.
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Affiliation(s)
- Mario Hofweber
- From the BioMedical Center, Cell Biology, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 9, 82152 Planegg-Martinsried.,the Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, and
| | - Dorothee Dormann
- From the BioMedical Center, Cell Biology, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 9, 82152 Planegg-Martinsried, .,the Graduate School of Systemic Neurosciences, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 2, 82152 Planegg-Martinsried, and.,the Munich Cluster for Systems Neurology (SyNergy), Feodor-Lynen-Strasse 17, 81377 Munich, Germany
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61
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Ribosomal flavours: an acquired taste for specific mRNAs? Biochem Soc Trans 2018; 46:1529-1539. [PMID: 30420413 DOI: 10.1042/bst20180160] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 09/14/2018] [Accepted: 09/17/2018] [Indexed: 12/20/2022]
Abstract
The regulation of translation is critical in almost every aspect of gene expression. Nonetheless, the ribosome is historically viewed as a passive player in this process. However, evidence is accumulating to suggest that variations in the ribosome can have an important influence on which mRNAs are translated. Scope for variation is provided via multiple avenues, including heterogeneity at the level of both ribosomal proteins and ribosomal RNAs and their covalent modifications. Together, these variations provide the potential for hundreds, if not thousands, of flavours of ribosome, each of which could have idiosyncratic preferences for the translation of certain messenger RNAs. Indeed, perturbations to this heterogeneity appear to affect specific subsets of transcripts and manifest as cell-type-specific diseases. This review provides a historical perspective of the ribosomal code hypothesis, before outlining the various sources of heterogeneity, their regulation and functional consequences for the cell.
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62
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Reineke LC, Cheema SA, Dubrulle J, Neilson JR. Chronic starvation induces noncanonical pro-death stress granules. J Cell Sci 2018; 131:jcs220244. [PMID: 30185525 PMCID: PMC6198455 DOI: 10.1242/jcs.220244] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 08/20/2018] [Indexed: 01/08/2023] Open
Abstract
Stress granules (SGs) assemble under stress-induced conditions that inhibit protein synthesis, including phosphorylation of eIF2α, inhibition of the RNA helicase eIF4a proteins or inactivation of mTORC1. Classically defined SGs are composed of translation initiation factors, 40S ribosomes, RNA-binding proteins and poly(A)+ mRNAs. As such, they represent an important compartment for storage of mRNAs and regulation of their translation. Emerging work on SGs indicates that these structures might promote cellular survival in diverse disease states. Yet, much work on SG formation and function employs acute stress conditions, which might not accurately reflect the chronic stresses that manifest in human disease. Here, we used prolonged nutrient starvation to model and investigate SG formation and function during chronic stress in a human cell line and mouse embryonic fibroblasts. Surprisingly, we found that SGs that form under chronic nutrient starvation lack 40S ribosomes, do not actively exchange their constituent components with cytoplasmic pools and promote cell death. We named these SGs starvation-induced SGs (stSGs). Our results on stSGs imply that SG assembly and function in the context of prolonged nutrient starvation stress differ significantly from what has been described for acute stress conditions.
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Affiliation(s)
- Lucas C Reineke
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shebna A Cheema
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
- Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Julien Dubrulle
- Integrated Microscopy Core, Baylor College of Medicine, Houston, TX 77030, USA
| | - Joel R Neilson
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
- Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
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