1
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Labbé K, LeBon L, King B, Vu N, Stoops EH, Ly N, Lefebvre AEYT, Seitzer P, Krishnan S, Heo JM, Bennett B, Sidrauski C. Specific activation of the integrated stress response uncovers regulation of central carbon metabolism and lipid droplet biogenesis. Nat Commun 2024; 15:8301. [PMID: 39333061 PMCID: PMC11436933 DOI: 10.1038/s41467-024-52538-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 09/10/2024] [Indexed: 09/29/2024] Open
Abstract
The integrated stress response (ISR) enables cells to cope with a variety of insults, but its specific contribution to downstream cellular outputs remains unclear. Using a synthetic tool, we selectively activate the ISR without co-activation of parallel pathways and define the resulting cellular state with multi-omics profiling. We identify time- and dose-dependent gene expression modules, with ATF4 driving only a small but sensitive subgroup that includes amino acid metabolic enzymes. This ATF4 response affects cellular bioenergetics, rerouting carbon utilization towards amino acid production and away from the tricarboxylic acid cycle and fatty acid synthesis. We also find an ATF4-independent reorganization of the lipidome that promotes DGAT-dependent triglyceride synthesis and accumulation of lipid droplets. While DGAT1 is the main driver of lipid droplet biogenesis, DGAT2 plays an essential role in buffering stress and maintaining cell survival. Together, we demonstrate the sufficiency of the ISR in promoting a previously unappreciated metabolic state.
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Affiliation(s)
| | - Lauren LeBon
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Bryan King
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Ngoc Vu
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Nina Ly
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | | | | | - Jin-Mi Heo
- Calico Life Sciences LLC, South San Francisco, CA, USA
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2
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Hanson FM, Ribeiro de Oliveira MI, Cross AK, Allen KE, Campbell SG. eIF2B localization and its regulation during the integrated stress response is cell-type specific. iScience 2024; 27:110851. [PMID: 39310746 PMCID: PMC11414691 DOI: 10.1016/j.isci.2024.110851] [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: 01/16/2024] [Revised: 04/30/2024] [Accepted: 08/27/2024] [Indexed: 09/25/2024] Open
Abstract
Eukaryotic initiation factor 2B (eIF2B) controls translation initiation by recycling inactive eIF2-GDP to active eIF2-GTP. Under cellular stress, the integrated stress response (ISR) is activated inhibiting eIF2B activity resulting in the translation attenuation and reprogramming of gene expression to overcome the stress. The ISR can dictate cell fate wherein chronic activation has pathological outcomes. Vanishing white matter disease (VWMD) is a chronic ISR-related disorder with mutations in eIF2B targeting astrocyte and oligodendrocyte cells. Regulation of eIF2B localization (eIF2B bodies) has been implicated in the ISR. We present evidence that neuronal and glial cell types possess distinct patterns of eIF2B bodies which change in a manner correlating to acute and chronic ISR activation. We also demonstrate that while neural and glial cell types respond similarly to the acute induction of the ISR a chronic ISR exerts cell-type specific differences. These findings provide key insights into neural cell responses and adaptation to cellular stress.
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Affiliation(s)
- Filipe M. Hanson
- Biomolecular Sciences Research Centre, Industry and Innovation Research Institute (IRI), Sheffield Hallam University, Sheffield S1 1WB, UK
| | - Madalena I. Ribeiro de Oliveira
- Biomolecular Sciences Research Centre, Industry and Innovation Research Institute (IRI), Sheffield Hallam University, Sheffield S1 1WB, UK
| | - Alison K. Cross
- Biomolecular Sciences Research Centre, Industry and Innovation Research Institute (IRI), Sheffield Hallam University, Sheffield S1 1WB, UK
| | - K. Elizabeth Allen
- Biomolecular Sciences Research Centre, Industry and Innovation Research Institute (IRI), Sheffield Hallam University, Sheffield S1 1WB, UK
| | - Susan G. Campbell
- Biomolecular Sciences Research Centre, Industry and Innovation Research Institute (IRI), Sheffield Hallam University, Sheffield S1 1WB, UK
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3
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Lohmann J, Herzog O, Rosenzweig K, Weingartner M. Thermal adaptation in plants: understanding the dynamics of translation factors and condensates. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:4258-4273. [PMID: 38630631 DOI: 10.1093/jxb/erae171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 04/16/2024] [Indexed: 04/19/2024]
Abstract
Plants, as sessile organisms, face the crucial challenge of adjusting growth and development with ever-changing environmental conditions. Protein synthesis is the fundamental process that enables growth of all organisms. Since elevated temperature presents a substantial threat to protein stability and function, immediate adjustments of protein synthesis rates are necessary to circumvent accumulation of proteotoxic stress and to ensure survival. This review provides an overview of the mechanisms that control translation under high-temperature stress by the modification of components of the translation machinery in plants, and compares them to yeast and metazoa. Recent research also suggests an important role for cytoplasmic biomolecular condensates, named stress granules, in these processes. Current understanding of the role of stress granules in translational regulation and of the molecular processes associated with translation that might occur within stress granules is also discussed.
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Affiliation(s)
- Julia Lohmann
- Institute of Plant Sciences and Microbiology, University of Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany
| | - Oliver Herzog
- Institute of Plant Sciences and Microbiology, University of Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany
| | - Kristina Rosenzweig
- Institute of Plant Sciences and Microbiology, University of Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany
| | - Magdalena Weingartner
- Institute of Plant Sciences and Microbiology, University of Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany
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4
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Borisova E, Newman AG, Couce Iglesias M, Dannenberg R, Schaub T, Qin B, Rusanova A, Brockmann M, Koch J, Daniels M, Turko P, Jahn O, Kaplan DR, Rosário M, Iwawaki T, Spahn CMT, Rosenmund C, Meierhofer D, Kraushar ML, Tarabykin V, Ambrozkiewicz MC. Protein translation rate determines neocortical neuron fate. Nat Commun 2024; 15:4879. [PMID: 38849354 PMCID: PMC11161512 DOI: 10.1038/s41467-024-49198-w] [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: 05/27/2022] [Accepted: 05/24/2024] [Indexed: 06/09/2024] Open
Abstract
The mammalian neocortex comprises an enormous diversity regarding cell types, morphology, and connectivity. In this work, we discover a post-transcriptional mechanism of gene expression regulation, protein translation, as a determinant of cortical neuron identity. We find specific upregulation of protein synthesis in the progenitors of later-born neurons and show that translation rates and concomitantly protein half-lives are inherent features of cortical neuron subtypes. In a small molecule screening, we identify Ire1α as a regulator of Satb2 expression and neuronal polarity. In the developing brain, Ire1α regulates global translation rates, coordinates ribosome traffic, and the expression of eIF4A1. Furthermore, we demonstrate that the Satb2 mRNA translation requires eIF4A1 helicase activity towards its 5'-untranslated region. Altogether, we show that cortical neuron diversity is generated by mechanisms operating beyond gene transcription, with Ire1α-safeguarded proteostasis serving as an essential regulator of brain development.
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Affiliation(s)
- Ekaterina Borisova
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Andrew G Newman
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Marta Couce Iglesias
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Rike Dannenberg
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Theres Schaub
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Bo Qin
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Alexandra Rusanova
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
- Tomsk National Research Medical Center of the Russian Academy of Sciences, Research Institute of Medical Genetics, Tomsk, Russia
| | - Marisa Brockmann
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Janina Koch
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Marieatou Daniels
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Paul Turko
- Institute of Integrative Neuroanatomy, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Olaf Jahn
- Neuroproteomics Group, Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Hermann-Rein-Str. 3, 37075, Göttingen, Germany
- Translational Neuroproteomics Group, Department of Psychiatry and Psychotherapy, University Medical Center Göttingen, Georg-August-University, Von-Siebold-Str. 5, 37075, Göttingen, Germany
| | - David R Kaplan
- Program in Neurosciences and Mental Health, Hospital for Sick Children and Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Marta Rosário
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany
| | - Takao Iwawaki
- Medical Research Institute, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku, Ishikawa, 920-0293, Japan
| | - Christian M T Spahn
- Institute of Medical Physics and Biophysics, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - Christian Rosenmund
- Institute of Neurophysiology, Charité-Universitätsmedizin Berlin, 10117, Berlin, Germany
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Matthew L Kraushar
- Max Planck Institute for Molecular Genetics, Ihnestraße 63-73, 14195, Berlin, Germany
| | - Victor Tarabykin
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany.
| | - Mateusz C Ambrozkiewicz
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117, Berlin, Germany.
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5
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Kim KQ, Nanjaraj Urs AN, Lasehinde V, Greenlaw AC, Hudson BH, Zaher HS. eIF4F complex dynamics are important for the activation of the integrated stress response. Mol Cell 2024; 84:2135-2151.e7. [PMID: 38848692 PMCID: PMC11189614 DOI: 10.1016/j.molcel.2024.04.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 12/08/2023] [Accepted: 04/19/2024] [Indexed: 06/09/2024]
Abstract
In response to stress, eukaryotes activate the integrated stress response (ISR) via phosphorylation of eIF2α to promote the translation of pro-survival effector genes, such as GCN4 in yeast. Complementing the ISR is the target of rapamycin (TOR) pathway, which regulates eIF4E function. Here, we probe translational control in the absence of eIF4E in Saccharomyces cerevisiae. Intriguingly, we find that loss of eIF4E leads to de-repression of GCN4 translation. In addition, we find that de-repression of GCN4 translation is accompanied by neither eIF2α phosphorylation nor reduction in initiator ternary complex (TC). Our data suggest that when eIF4E levels are depleted, GCN4 translation is de-repressed via a unique mechanism that may involve faster scanning by the small ribosome subunit due to increased local concentration of eIF4A. Overall, our findings suggest that relative levels of eIF4F components are key to ribosome dynamics and may play important roles in translational control of gene expression.
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Affiliation(s)
- Kyusik Q Kim
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | | | - Victor Lasehinde
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Alison C Greenlaw
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Benjamin H Hudson
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Hani S Zaher
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA.
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6
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Anastas V, Chavdoula E, La Ferlita A, Soysal B, Cosentini I, Nigita G, Kearse MG, Tsichlis PN. KDM2B is required for ribosome biogenesis and its depletion unequally affects mRNA translation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.22.595403. [PMID: 38826406 PMCID: PMC11142201 DOI: 10.1101/2024.05.22.595403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
KDM2B is a JmjC domain lysine demethylase, which promotes cell immortalization, stem cell self-renewal and tumorigenesis. Here we employed a multi-omics strategy to address its role in ribosome biogenesis and mRNA translation. These processes are required to sustain cell proliferation, an important cancer hallmark. Contrary to earlier observations, KDM2B promotes ribosome biogenesis by stimulating the transcription of genes encoding ribosome biogenesis factors and ribosomal proteins, particularly those involved in the biogenesis of the 40S ribosomal subunits. Knockdown of KDM2B impaired the assembly of the small and large subunit processomes, as evidenced by specific defects in pre-ribosomal RNA processing. The final outcome was a decrease in the rate of ribosome assembly and in the abundance of ribosomes, and inhibition of mRNA translation. The inhibition of translation was distributed unequally among mRNAs with different features, suggesting that mRNA-embedded properties influence how mRNAs interpret ribosome abundance. This study identified a novel mechanism contributing to the regulation of translation and provided evidence for a rich biology elicited by a pathway that depends on KDM2B, and perhaps other regulators of translation.
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Affiliation(s)
- Vollter Anastas
- Tufts Graduate School of Biomedical Sciences, Program in Genetics, Boston, MA, United States
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- The Ohio State University, Comprehensive Cancer Center, Columbus, OH, United States
| | - Evangelia Chavdoula
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- The Ohio State University, Comprehensive Cancer Center, Columbus, OH, United States
| | - Alessandro La Ferlita
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- The Ohio State University, Comprehensive Cancer Center, Columbus, OH, United States
| | - Burak Soysal
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- The Ohio State University, Comprehensive Cancer Center, Columbus, OH, United States
| | - Ilaria Cosentini
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- The Ohio State University, Comprehensive Cancer Center, Columbus, OH, United States
- Institute for Biomedical Research and Innovation (IRIB), National Research Council of Italy (CNR), Palermo, Italy
| | - Giovanni Nigita
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- The Ohio State University, Comprehensive Cancer Center, Columbus, OH, United States
| | - Michael G Kearse
- Department of Biological Chemistry and Pharmacology, Center for RNA Biology, The Ohio State University, Columbus, OH, United States
| | - Philip N Tsichlis
- Tufts Graduate School of Biomedical Sciences, Program in Genetics, Boston, MA, United States
- Department of Cancer Biology and Genetics, The Ohio State University, Columbus, OH, United States
- The Ohio State University, Comprehensive Cancer Center, Columbus, OH, United States
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7
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Deng J, Liu J, Chen W, Liang Q, He Y, Sun G. Effects of Natural Products through Inhibiting Endoplasmic Reticulum Stress on Attenuation of Idiopathic Pulmonary Fibrosis. Drug Des Devel Ther 2024; 18:1627-1650. [PMID: 38774483 PMCID: PMC11108075 DOI: 10.2147/dddt.s388920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 04/23/2024] [Indexed: 05/24/2024] Open
Abstract
With ever-increasing intensive studies of idiopathic pulmonary fibrosis (IPF), significant progresses have been made. Endoplasmic reticulum stress (ERS)/unfolded protein reaction (UPR) is associated with the development and progression of IPF, and targeting ERS/UPR may be beneficial in the treatment of IPF. Natural product is a tremendous source of new drug discovery, and accumulating studies have reported that many natural products show potential therapeutic effects for IPF via modulating one or more branches of the ERS signaling pathway. Therefore, this review focuses on critical roles of ERS in IPF development, and summarizes herbal preparations and bioactive compounds which protect against IPF through regulating ERS.
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Affiliation(s)
- JiuLing Deng
- Department of Pharmacy, Shanghai Fifth People’s Hospital, Fudan University, Shanghai, 200240, People’s Republic of China
| | - Jing Liu
- Department of Pharmacy, Shanghai Fifth People’s Hospital, Fudan University, Shanghai, 200240, People’s Republic of China
| | - WanSheng Chen
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, People’s Republic of China
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, People’s Republic of China
| | - Qing Liang
- Department of Pharmacy, Shanghai Fifth People’s Hospital, Fudan University, Shanghai, 200240, People’s Republic of China
| | - YuQiong He
- Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, People’s Republic of China
- Department of Pharmacy, Changzheng Hospital, Second Military Medical University, Shanghai, 200003, People’s Republic of China
| | - GuangChun Sun
- Department of Pharmacy, Shanghai Fifth People’s Hospital, Fudan University, Shanghai, 200240, People’s Republic of China
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8
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Kucharska-Lusina A, Skrzypek M, Binda A, Majsterek I. Gene Expression Profiling to Unfolded Proteins Response as a Risk Modulator of Patients with Rheumatoid Arthritis. Int J Mol Sci 2024; 25:4854. [PMID: 38732072 PMCID: PMC11084936 DOI: 10.3390/ijms25094854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/17/2024] [Accepted: 04/24/2024] [Indexed: 05/13/2024] Open
Abstract
Rheumatoid arthritis (RA) is a chronic inflammatory disease. Despite new methods of diagnostics and treatment as well as extensive biological and immunosuppressive treatment, the etiology of RA is not fully understood. Moreover, the problem of diagnosis and treatment of RA patients is still current and affects a large group of patients. It is suggested that endoplasmic reticulum (ER)-related features may impair adaptation to chronic stress, inferring the risk of rheumatoid arthritis. The main goal in this study was evaluation of changes in mRNA translation to determine chronic ER stress conditions in rheumatoid arthritis patients. The study group consist of 86 individuals including a total of 56 rheumatoid arthritis patients and 30 healthy controls. The expression level of mRNA form blood samples of RA patients as well as controls of the unfolded protein response (UPR)-associated genes (p-eIF2, BCL-2, PERK, ATF4, and BAX) were investigated using real-time qPCR. GAPDH expression was used as a standard control. Considering the median, the expression levels of PERK, BCL-2, p-eIF2, ATF4, and BAX were found to be significantly increased in the blood of RA patients compared with the control group. The p-value for the PERK gene was 0.0000000036, the p-value for the BCL-2 gene was 0.000000014, the p-value for the p-eIF2 gene was 0.006948, the p-value for the ATF4 gene was 0.0000056, and the p-value for the BAX gene was 0.00019, respectively. Thus, it can be concluded that the targeting of the components of the PERK-dependent UPR signaling pathway via small-molecule PERK inhibitors may contribute to the development of novel, innovative treatment strategies against rheumatoid arthritis.
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Affiliation(s)
| | | | | | - Ireneusz Majsterek
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, 92-215 Lodz, Poland; (A.K.-L.); (M.S.); (A.B.)
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9
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Jiogo H, Crist C. Navigating translational control of gene expression in satellite cells. Curr Top Dev Biol 2024; 158:253-277. [PMID: 38670709 DOI: 10.1016/bs.ctdb.2024.02.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
Satellite cells, named for their satellite position around the sarcolemma of the myofibre, are responsible for skeletal muscle regeneration. Satellite cells normally reside in a quiescent state, but rapidly activate the myogenic program and the cell cycle in response to injury. Translational control of gene expression has emerged as an important regulator of satellite cell activity. Quiescent satellite cells maintain low levels of protein synthesis and selectively translate specific mRNAs to conserve limited energy. Activated satellite cells rapidly restore global protein synthesis to meet the demands of proliferating myogenic progenitors that participate in muscle repair. We propose a model by which translational control enables rapid protein level changes in response to injury-induced environmental shifts, serving as both a brake mechanism during quiescence and an accelerator for injury response. In this Chapter, we navigate the processing, translation and metabolism of newly transcribed mRNAs. We review the modifications of mRNA that occur during mRNA processing in the nucleus of satellite cells, and illustrate how these modifications impact the translation and stability of mRNAs. In the cytoplasm, we review how pathways work in concert to regulate protein synthesis globally, while trans acting microRNAs and RNA binding proteins modify specific mRNA translation within a context of tightly regulated protein synthesis. While navigating translational control of gene expression in satellite cells, this chapter reveals that despite significant progress, the field remains nascent in the broader scope of translational control in cell biology. We propose that future investigations will benefit from incorporating emerging global analyses to study translational control of gene expression in rare satellite cells, and we pose unanswered questions that warrant future exploration.
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Affiliation(s)
- Holly Jiogo
- Department of Human Genetics, McGill University, Montreal, QC, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada
| | - Colin Crist
- Department of Human Genetics, McGill University, Montreal, QC, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, QC, Canada.
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10
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Brito Querido J, Díaz-López I, Ramakrishnan V. The molecular basis of translation initiation and its regulation in eukaryotes. Nat Rev Mol Cell Biol 2024; 25:168-186. [PMID: 38052923 DOI: 10.1038/s41580-023-00624-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2023] [Indexed: 12/07/2023]
Abstract
The regulation of gene expression is fundamental for life. Whereas the role of transcriptional regulation of gene expression has been studied for several decades, it has been clear over the past two decades that post-transcriptional regulation of gene expression, of which translation regulation is a major part, can be equally important. Translation can be divided into four main stages: initiation, elongation, termination and ribosome recycling. Translation is controlled mainly during its initiation, a process which culminates in a ribosome positioned with an initiator tRNA over the start codon and, thus, ready to begin elongation of the protein chain. mRNA translation has emerged as a powerful tool for the development of innovative therapies, yet the detailed mechanisms underlying the complex process of initiation remain unclear. Recent studies in yeast and mammals have started to shed light on some previously unclear aspects of this process. In this Review, we discuss the current state of knowledge on eukaryotic translation initiation and its regulation in health and disease. Specifically, we focus on recent advances in understanding the processes involved in assembling the 43S pre-initiation complex and its recruitment by the cap-binding complex eukaryotic translation initiation factor 4F (eIF4F) at the 5' end of mRNA. In addition, we discuss recent insights into ribosome scanning along the 5' untranslated region of mRNA and selection of the start codon, which culminates in joining of the 60S large subunit and formation of the 80S initiation complex.
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Affiliation(s)
- Jailson Brito Querido
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Irene Díaz-López
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - V Ramakrishnan
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
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11
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Tidu A, Martin F. The interplay between cis- and trans-acting factors drives selective mRNA translation initiation in eukaryotes. Biochimie 2024; 217:20-30. [PMID: 37741547 DOI: 10.1016/j.biochi.2023.09.017] [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: 05/04/2023] [Revised: 07/20/2023] [Accepted: 09/14/2023] [Indexed: 09/25/2023]
Abstract
Translation initiation consists in the assembly of the small and large ribosomal subunits on the start codon. This important step directly modulates the general proteome in living cells. Recently, genome wide studies revealed unexpected translation initiation events from unsuspected novel open reading frames resulting in the synthesis of a so-called 'dark proteome'. Indeed, the identification of the start codon by the translation machinery is a critical step that defines the translational landscape of the cell. Therefore, translation initiation is a highly regulated process in all organisms. In this review, we focus on the various cis- and trans-acting factors that rule the regulation of translation initiation in eukaryotes. Recent discoveries have shown that the guidance of the translation machinery for the choice of the start codon require sophisticated molecular mechanisms. In particular, the 5'UTR and the coding sequences contain cis-acting elements that trigger the use of AUG codons but also non-AUG codons to initiate protein synthesis. The use of these alternative start codons is also largely influenced by numerous trans-acting elements that drive selective mRNA translation in response to environmental changes.
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Affiliation(s)
- Antonin Tidu
- Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, Architecture et Réactivité de l'ARN, CNRS UPR9002, 2, allée Konrad Roentgen, F-67084 Strasbourg, France
| | - Franck Martin
- Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire, Architecture et Réactivité de l'ARN, CNRS UPR9002, 2, allée Konrad Roentgen, F-67084 Strasbourg, France.
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12
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Ventoso I, Berlanga JJ, Toribio R, Díaz-López I. Translational Control of Alphavirus-Host Interactions: Implications in Viral Evolution, Tropism and Antiviral Response. Viruses 2024; 16:205. [PMID: 38399981 PMCID: PMC10893052 DOI: 10.3390/v16020205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/19/2024] [Accepted: 01/24/2024] [Indexed: 02/25/2024] Open
Abstract
Alphaviruses can replicate in arthropods and in many vertebrate species including humankind, but only in vertebrate cells do infections with these viruses result in a strong inhibition of host translation and transcription. Translation shutoff by alphaviruses is a multifactorial process that involves both host- and virus-induced mechanisms, and some of them are not completely understood. Alphavirus genomes contain cis-acting elements (RNA structures and dinucleotide composition) and encode protein activities that promote the translational and transcriptional resistance to type I IFN-induced antiviral effectors. Among them, IFIT1, ZAP and PKR have played a relevant role in alphavirus evolution, since they have promoted the emergence of multiple viral evasion mechanisms at the translational level. In this review, we will discuss how the adaptations of alphaviruses to vertebrate hosts likely involved the acquisition of new features in viral mRNAs and proteins to overcome the effect of type I IFN.
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Affiliation(s)
- Iván Ventoso
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid (UAM), 28049 Madrid, Spain;
| | - Juan José Berlanga
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid (UAM), 28049 Madrid, Spain;
| | - René Toribio
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (UPM-INIA), 28049 Madrid, Spain;
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13
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van der Knaap MS, Bugiani M, Abbink TEM. Vanishing white matter. HANDBOOK OF CLINICAL NEUROLOGY 2024; 204:77-94. [PMID: 39322396 DOI: 10.1016/b978-0-323-99209-1.00015-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/27/2024]
Abstract
"Vanishing white matter" (VWM) is a leukodystrophy caused by autosomal recessive pathogenic variants in the genes encoding the subunits of eukaryotic initiation factor 2B (eIF2B). Disease onset and disease course are extremely variable. Onset varies from the antenatal period until senescence. The age of onset is predictive of disease severity. VWM is characterized by chronic neurologic deterioration and, additionally, episodes of rapid and major neurologic decline, provoked by stresses such as febrile infections and minor head trauma. The disease is dominated by degeneration of the white matter of the central nervous system due to dysfunction of oligodendrocytes and in particular astrocytes. Organs other than the brain are rarely affected, with the exception of the ovaries. The reason for the selective vulnerability of the white matter of the central nervous system and, less consistently, the ovaries is poorly understood. eIF2B is a central regulatory factor in the integrated stress response (ISR). Genetic variants decrease eIF2B activity and thereby cause constitutive activation of the ISR downstream of eIF2B. Strikingly, the ISR is specifically activated in astrocytes. Modulation of eIF2B activity and ISR activation in VWM mouse models impacts disease severity, revealing eIF2B-regulated pathways as potential druggable targets.
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Affiliation(s)
- Marjo S van der Knaap
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam University Medical Center, and Amsterdam Neuroscience, Cellular & Molecular Mechanisms, Vrije Universiteit, Amsterdam, The Netherlands.
| | - Marianna Bugiani
- Department of Pathology, Amsterdam Leukodystrophy Center, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Truus E M Abbink
- Department of Child Neurology, Amsterdam Leukodystrophy Center, Emma Children's Hospital, Amsterdam UMC, Amsterdam, The Netherlands; Amsterdam Neuroscience, Cellular & Molecular Mechanisms, Vrije Universiteit, Amsterdam, The Netherlands
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14
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Barrington CL, Galindo G, Koch AL, Horton ER, Morrison EJ, Tisa S, Stasevich TJ, Rissland OS. Synonymous codon usage regulates translation initiation. Cell Rep 2023; 42:113413. [PMID: 38096059 PMCID: PMC10790568 DOI: 10.1016/j.celrep.2023.113413] [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: 05/13/2023] [Revised: 08/30/2023] [Accepted: 10/25/2023] [Indexed: 12/30/2023] Open
Abstract
Nonoptimal synonymous codons repress gene expression, but the underlying mechanisms are poorly understood. We and others have previously shown that nonoptimal codons slow translation elongation speeds and thereby trigger messenger RNA (mRNA) degradation. Nevertheless, transcript levels are often insufficient to explain protein levels, suggesting additional mechanisms by which codon usage regulates gene expression. Using reporters in human and Drosophila cells, we find that transcript levels account for less than half of the variation in protein abundance due to codon usage. This discrepancy is explained by translational differences whereby nonoptimal codons repress translation initiation. Nonoptimal transcripts are also less bound by the translation initiation factors eIF4E and eIF4G1, providing a mechanistic explanation for their reduced initiation rates. Importantly, translational repression can occur without mRNA decay and deadenylation, and it does not depend on the known nonoptimality sensor, CNOT3. Our results reveal a potent mechanism of regulation by codon usage where nonoptimal codons repress further rounds of translation.
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Affiliation(s)
- Chloe L Barrington
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Gabriel Galindo
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Amanda L Koch
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Emma R Horton
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Evan J Morrison
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Samantha Tisa
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Timothy J Stasevich
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Olivia S Rissland
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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15
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Black A, Williams TD, Soubigou F, Joshua IM, Zhou H, Lamoliatte F, Rousseau A. The ribosome-associated chaperone Zuo1 controls translation upon TORC1 inhibition. EMBO J 2023; 42:e113240. [PMID: 37984430 PMCID: PMC10711665 DOI: 10.15252/embj.2022113240] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 10/23/2023] [Accepted: 10/26/2023] [Indexed: 11/22/2023] Open
Abstract
Protein requirements of eukaryotic cells are ensured by proteostasis, which is mediated by tight control of TORC1 activity. Upon TORC1 inhibition, protein degradation is increased and protein synthesis is reduced through inhibition of translation initiation to maintain cell viability. Here, we show that the ribosome-associated complex (RAC)/Ssb chaperone system, composed of the HSP70 chaperone Ssb and its HSP40 co-chaperone Zuo1, is required to maintain proteostasis and cell viability under TORC1 inhibition in Saccharomyces cerevisiae. In the absence of Zuo1, translation does not decrease in response to the loss of TORC1 activity. A functional interaction between Zuo1 and Ssb is required for proper translational control and proteostasis maintenance upon TORC1 inhibition. Furthermore, we have shown that the rapid degradation of eIF4G following TORC1 inhibition is mediated by autophagy and is prevented in zuo1Δ cells, contributing to decreased survival in these conditions. We found that autophagy is defective in zuo1Δ cells, which impedes eIF4G degradation upon TORC1 inhibition. Our findings identify an essential role for RAC/Ssb in regulating translation in response to changes in TORC1 signalling.
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Affiliation(s)
- Ailsa Black
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life SciencesUniversity of DundeeDundeeUK
| | - Thomas D Williams
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life SciencesUniversity of DundeeDundeeUK
| | - Flavie Soubigou
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life SciencesUniversity of DundeeDundeeUK
| | - Ifeoluwapo M Joshua
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life SciencesUniversity of DundeeDundeeUK
| | - Houjiang Zhou
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life SciencesUniversity of DundeeDundeeUK
| | - Frederic Lamoliatte
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life SciencesUniversity of DundeeDundeeUK
| | - Adrien Rousseau
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life SciencesUniversity of DundeeDundeeUK
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16
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Shieh AW, Bansal SK, Zuo Z, Wang SH. Transcriptome-wide profiling of acute stress induced changes in ribosome occupancy level using external standards. PLoS One 2023; 18:e0294308. [PMID: 37988379 PMCID: PMC10662766 DOI: 10.1371/journal.pone.0294308] [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: 11/02/2022] [Accepted: 10/30/2023] [Indexed: 11/23/2023] Open
Abstract
Acute cellular stress is known to induce a global reduction in mRNA translation through suppression of cap dependent translation. Selective translation in response to acute stress has been shown to play important roles in regulating the stress response. However, accurately profiling translational changes transcriptome-wide in response to acute cellular stress has been challenging. Commonly used data normalization methods operate on the assumption that any systematic shifts are experimental artifacts. Consequently, if applied to profiling acute cellular stress-induced mRNA translation changes, these methods are expected to produce biased estimates. To address this issue, we designed, produced, and evaluated a panel of 16 oligomers to serve as external standards for ribosome profiling studies. Using Sodium Arsenite treatment-induced oxidative stress in lymphoblastoid cell lines as a model system, we applied spike-in oligomers as external standards. We found our spike-in oligomers to display a strong linear correlation between the observed and the expected quantification, with small ratio compression at the lower concentration range. Using the expected fold changes constructed from spike-in controls, we found in our dataset that TMM normalization, a popular global scaling normalization approach, produced 87.5% false positives at a significant cutoff that is expected to produce only 10% false positive discoveries. In addition, TMM normalization produced a systematic shift of fold change by 3.25 fold. These results highlight the consequences of applying global scaling approaches to conditions that clearly violate their key assumptions. In contrast, we found RUVg normalization using spike-in oligomers as control genes recapitulated the expected stress induced global reduction of translation and resulted in little, if any, systematic shifts in the expected fold change. Our results clearly demonstrated the utility of our spike-in oligomers, both for constructing expected results as controls and for data normalization.
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Affiliation(s)
- Annie W. Shieh
- Center for Human Genetics, The Brown foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Sandeep K. Bansal
- Center for Human Genetics, The Brown foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Zhen Zuo
- Baylor College of Medicine, Houston, TX, United States of America
| | - Sidney H. Wang
- Center for Human Genetics, The Brown foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
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17
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Ricciardi-Jorge T, da Rocha EL, Gonzalez-Kozlova E, Rodrigues-Luiz GF, Ferguson BJ, Sweeney T, Irigoyen N, Mansur DS. PKR-mediated stress response enhances dengue and Zika virus replication. mBio 2023; 14:e0093423. [PMID: 37732809 PMCID: PMC10653888 DOI: 10.1128/mbio.00934-23] [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: 05/22/2023] [Accepted: 08/01/2023] [Indexed: 09/22/2023] Open
Abstract
IMPORTANCE One of the fundamental features that make viruses intracellular parasites is the necessity to use cellular translational machinery. Hence, this is a crucial checkpoint for controlling infections. Here, we show that dengue and Zika viruses, responsible for nearly 400 million infections every year worldwide, explore such control for optimal replication. Using immunocompetent cells, we demonstrate that arrest of protein translations happens after sensing of dsRNA and that the information required to avoid this blocking is contained in viral 5'-UTR. Our work, therefore, suggests that the non-canonical translation described for these viruses is engaged when the intracellular stress response is activated.
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Affiliation(s)
- Taissa Ricciardi-Jorge
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil
- The Pirbright Institute, Woking, United Kingdom
| | - Edroaldo Lummertz da Rocha
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil
| | - Edgar Gonzalez-Kozlova
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil
- Icahn School of Medicine, New York, USA
| | - Gabriela Flavia Rodrigues-Luiz
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil
| | - Brian J. Ferguson
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | | | - Nerea Irigoyen
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Daniel Santos Mansur
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil
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18
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Iyer KV, Müller M, Tittel LS, Winz ML. Molecular Highway Patrol for Ribosome Collisions. Chembiochem 2023; 24:e202300264. [PMID: 37382189 DOI: 10.1002/cbic.202300264] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 06/25/2023] [Accepted: 06/28/2023] [Indexed: 06/30/2023]
Abstract
During translation, messenger RNAs (mRNAs) are decoded by ribosomes which can stall for various reasons. These include chemical damage, codon composition, starvation, or translation inhibition. Trailing ribosomes can collide with stalled ribosomes, potentially leading to dysfunctional or toxic proteins. Such aberrant proteins can form aggregates and favor diseases, especially neurodegeneration. To prevent this, both eukaryotes and bacteria have evolved different pathways to remove faulty nascent peptides, mRNAs and defective ribosomes from the collided complex. In eukaryotes, ubiquitin ligases play central roles in triggering downstream responses and several complexes have been characterized that split affected ribosomes and facilitate degradation of the various components. As collided ribosomes signal translation stress to affected cells, in eukaryotes additional stress response pathways are triggered when collisions are sensed. These pathways inhibit translation and modulate cell survival and immune responses. Here, we summarize the current state of knowledge about rescue and stress response pathways triggered by ribosome collisions.
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Affiliation(s)
- Kaushik Viswanathan Iyer
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128, Mainz, Germany
| | - Max Müller
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128, Mainz, Germany
| | - Lena Sophie Tittel
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128, Mainz, Germany
| | - Marie-Luise Winz
- Institute for Pharmaceutical and Biomedical Sciences, Johannes Gutenberg-University Mainz, Staudingerweg 5, 55128, Mainz, Germany
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19
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Lahiri A, Walton JC, Zhang N, Billington N, DeVries AC, Meares GP. Astrocytic deletion of protein kinase R-like ER kinase (PERK) does not affect learning and memory in aged mice but worsens outcome from experimental stroke. J Neurosci Res 2023; 101:1586-1610. [PMID: 37314006 PMCID: PMC10524975 DOI: 10.1002/jnr.25224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 05/22/2023] [Accepted: 05/27/2023] [Indexed: 06/15/2023]
Abstract
Aging is associated with cognitive decline and is the main risk factor for a myriad of conditions including neurodegeneration and stroke. Concomitant with aging is the progressive accumulation of misfolded proteins and loss of proteostasis. Accumulation of misfolded proteins in the endoplasmic reticulum (ER) leads to ER stress and activation of the unfolded protein response (UPR). The UPR is mediated, in part, by the eukaryotic initiation factor 2α (eIF2α) kinase protein kinase R-like ER kinase (PERK). Phosphorylation of eIF2α reduces protein translation as an adaptive mechanism but this also opposes synaptic plasticity. PERK, and other eIF2α kinases, have been widely studied in neurons where they modulate both cognitive function and response to injury. The impact of astrocytic PERK signaling in cognitive processes was previously unknown. To examine this, we deleted PERK from astrocytes (AstroPERKKO ) and examined the impact on cognitive functions in middle-aged and old mice of both sexes. Additionally, we tested the outcome following experimental stroke using the transient middle cerebral artery occlusion (MCAO) model. Tests of short-term and long-term learning and memory as well as of cognitive flexibility in middle-aged and old mice revealed that astrocytic PERK does not regulate these processes. Following MCAO, AstroPERKKO had increased morbidity and mortality. Collectively, our data demonstrate that astrocytic PERK has limited impact on cognitive function and has a more prominent role in the response to neural injury.
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Affiliation(s)
| | | | | | | | - A Courtney DeVries
- Department of Neuroscience
- Rockefeller Neuroscience Institute
- Department of Medicine, Division of Hematology and Oncology
- WVU Cancer Institute, Morgantown, WV- 26506, USA
- West Virginia Clinical and Translational Science Institute, West Virginia University, Morgantown, WV- 26506, USA
| | - Gordon P. Meares
- Department of Microbiology, Immunology and Cell Biology
- Department of Neuroscience
- Rockefeller Neuroscience Institute
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20
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Mukhopadhyay S, Amodeo ME, Lee ASY. eIF3d controls the persistent integrated stress response. Mol Cell 2023; 83:3303-3313.e6. [PMID: 37683648 PMCID: PMC10528100 DOI: 10.1016/j.molcel.2023.08.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 05/26/2023] [Accepted: 08/09/2023] [Indexed: 09/10/2023]
Abstract
Cells respond to intrinsic and extrinsic stresses by reducing global protein synthesis and activating gene programs necessary for survival. Here, we show that the integrated stress response (ISR) is driven by the non-canonical cap-binding protein eIF3d that acts as a critical effector to control core stress response orchestrators, the translation factor eIF2α and the transcription factor ATF4. We find that during persistent stress, eIF3d activates the translation of the kinase GCN2, inducing eIF2α phosphorylation and inhibiting general protein synthesis. In parallel, eIF3d upregulates the m6A demethylase ALKBH5 to drive 5' UTR-specific demethylation of stress response genes, including ATF4. Ultimately, this cascade converges on ATF4 expression by increasing mRNA engagement of translation machinery and enhancing ribosome bypass of upstream open reading frames (uORFs). Our results reveal that eIF3d acts in a life-or-death decision point during chronic stress and uncover a synergistic signaling mechanism in which translational cascades complement transcriptional amplification to control essential cellular processes.
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Affiliation(s)
- Shaoni Mukhopadhyay
- Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Maria E Amodeo
- Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Amy S Y Lee
- Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
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21
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Chen Y, Quan S, Patil V, Kunjamma RB, Tokars HM, Leisten ED, Joy G, Wills S, Chan JR, Wong YC, Popko B. Insights into the mechanism of oligodendrocyte protection and remyelination enhancement by the integrated stress response. Glia 2023; 71:2180-2195. [PMID: 37203250 PMCID: PMC10681276 DOI: 10.1002/glia.24386] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 04/24/2023] [Accepted: 05/05/2023] [Indexed: 05/20/2023]
Abstract
central nervous system (CNS) inflammation triggers activation of the integrated stress response (ISR). We previously reported that prolonging the ISR protects remyelinating oligodendrocytes and promotes remyelination in the presence of inflammation. However, the exact mechanisms through which this occurs remain unknown. Here, we investigated whether the ISR modulator Sephin1 in combination with the oligodendrocyte differentiation enhancing reagent bazedoxifene (BZA) is able to accelerate remyelination under inflammation, and the underlying mechanisms mediating this pathway. We find that the combined treatment of Sephin1 and BZA is sufficient to accelerate early-stage remyelination in mice with ectopic IFN-γ expression in the CNS. IFN-γ, which is a critical inflammatory cytokine in multiple sclerosis (MS), inhibits oligodendrocyte precursor cell (OPC) differentiation in culture and triggers a mild ISR. Mechanistically, we further show that BZA promotes OPC differentiation in the presence of IFN-γ, while Sephin1 enhances the IFN-γ-induced ISR by reducing protein synthesis and increasing RNA stress granule formation in differentiating oligodendrocytes. Finally, pharmacological suppression of the ISR blocks stress granule formation in vitro and partially lessens the beneficial effect of Sephin1 on disease progression in a mouse model of MS, experimental autoimmune encephalitis (EAE). Overall, our findings uncover distinct mechanisms of action of BZA and Sephin1 on oligodendrocyte lineage cells under inflammatory stress, suggesting that a combination therapy may effectively promote restoring neuronal function in MS patients.
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Affiliation(s)
- Yanan Chen
- Deptment of Biology, Loyola University Chicago, Chicago, IL, 60660, USA
| | - Songhua Quan
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Vaibhav Patil
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Rejani B. Kunjamma
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Haley M. Tokars
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Eric D. Leisten
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Godwin Joy
- Deptment of Biology, Loyola University Chicago, Chicago, IL, 60660, USA
| | - Samantha Wills
- Deptment of Biology, Loyola University Chicago, Chicago, IL, 60660, USA
| | - Jonah R. Chan
- Weill Institute for Neuroscience, Department of Neurology, University of California, San Francisco, CA, 94158, USA
| | - Yvette C. Wong
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Brian Popko
- Department of Neurology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
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22
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Cardenal Peralta C, Vandroux P, Neumann-Arnold L, Panvert M, Fagart J, Seufert W, Mechulam Y, Schmitt E. Binding of human Cdc123 to eIF2γ. J Struct Biol 2023; 215:108006. [PMID: 37507029 DOI: 10.1016/j.jsb.2023.108006] [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: 06/28/2023] [Revised: 07/18/2023] [Accepted: 07/25/2023] [Indexed: 07/30/2023]
Abstract
Eukaryotic initiation factor 2 (eIF2) plays a key role in protein synthesis and in its regulation. The assembly of this heterotrimeric factor is facilitated by Cdc123, a member of the ATP grasp family that binds the γ subunit of eIF2. Notably, some mutations related to MEHMO syndrome, an X-linked intellectual disability, affect Cdc123-mediated eIF2 assembly. The mechanism of action of Cdc123 is unclear and structural information for the human protein is awaited. Here, the crystallographic structure of human Cdc123 (Hs-Cdc123) bound to domain 3 of human eIF2γ (Hs-eIF2γD3) was determined. The structure shows that the domain 3 of eIF2γ is bound to domain 1 of Cdc123. In addition, the long C-terminal region of Hs-Cdc123 provides a link between the ATP and Hs-eIF2γD3 binding sites. A thermal shift assay shows that ATP is tightly bound to Cdc123 whereas the affinity of ADP is much smaller. Yeast cell viability experiments, western blot analysis and two-hybrid assays show that ATP is important for the function of Hs-Cdc123 in eIF2 assembly. These data and recent findings allow us to propose a refined model to explain the mechanism of action of Cdc123 in eIF2 assembly.
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Affiliation(s)
- Cristina Cardenal Peralta
- Laboratoire de Biologie Structurale de la Cellule, BIOC, Ecole polytechnique, CNRS, Institut Polytechnique de Paris, 91128 Palaiseau cedex, France
| | - Paul Vandroux
- Laboratoire de Biologie Structurale de la Cellule, BIOC, Ecole polytechnique, CNRS, Institut Polytechnique de Paris, 91128 Palaiseau cedex, France
| | - Lea Neumann-Arnold
- Department of Genetics, Regensburg Center for Biochemistry, University of Regensburg, Regensburg, Germany
| | - Michel Panvert
- Laboratoire de Biologie Structurale de la Cellule, BIOC, Ecole polytechnique, CNRS, Institut Polytechnique de Paris, 91128 Palaiseau cedex, France
| | - Jérôme Fagart
- Laboratoire de Biologie Structurale de la Cellule, BIOC, Ecole polytechnique, CNRS, Institut Polytechnique de Paris, 91128 Palaiseau cedex, France
| | - Wolfgang Seufert
- Department of Genetics, Regensburg Center for Biochemistry, University of Regensburg, Regensburg, Germany.
| | - Yves Mechulam
- Laboratoire de Biologie Structurale de la Cellule, BIOC, Ecole polytechnique, CNRS, Institut Polytechnique de Paris, 91128 Palaiseau cedex, France
| | - Emmanuelle Schmitt
- Laboratoire de Biologie Structurale de la Cellule, BIOC, Ecole polytechnique, CNRS, Institut Polytechnique de Paris, 91128 Palaiseau cedex, France.
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23
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Wang S, Sun S. Translation dysregulation in neurodegenerative diseases: a focus on ALS. Mol Neurodegener 2023; 18:58. [PMID: 37626421 PMCID: PMC10464328 DOI: 10.1186/s13024-023-00642-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023] Open
Abstract
RNA translation is tightly controlled in eukaryotic cells to regulate gene expression and maintain proteome homeostasis. RNA binding proteins, translation factors, and cell signaling pathways all modulate the translation process. Defective translation is involved in multiple neurological diseases including amyotrophic lateral sclerosis (ALS). ALS is a progressive neurodegenerative disorder and poses a major public health challenge worldwide. Over the past few years, tremendous advances have been made in the understanding of the genetics and pathogenesis of ALS. Dysfunction of RNA metabolisms, including RNA translation, has been closely associated with ALS. Here, we first introduce the general mechanisms of translational regulation under physiological and stress conditions and review well-known examples of translation defects in neurodegenerative diseases. We then focus on ALS-linked genes and discuss the recent progress on how translation is affected by various mutant genes and the repeat expansion-mediated non-canonical translation in ALS.
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Affiliation(s)
- Shaopeng Wang
- Department of Physiology and Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Shuying Sun
- Department of Physiology and Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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Lines CL, McGrath MJ, Dorwart T, Conn CS. The integrated stress response in cancer progression: a force for plasticity and resistance. Front Oncol 2023; 13:1206561. [PMID: 37601686 PMCID: PMC10435748 DOI: 10.3389/fonc.2023.1206561] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 06/07/2023] [Indexed: 08/22/2023] Open
Abstract
During their quest for growth, adaptation, and survival, cancer cells create a favorable environment through the manipulation of normal cellular mechanisms. They increase anabolic processes, including protein synthesis, to facilitate uncontrolled proliferation and deplete the tumor microenvironment of resources. As a dynamic adaptation to the self-imposed oncogenic stress, cancer cells promptly hijack translational control to alter gene expression. Rewiring the cellular proteome shifts the phenotypic balance between growth and adaptation to promote therapeutic resistance and cancer cell survival. The integrated stress response (ISR) is a key translational program activated by oncogenic stress that is utilized to fine-tune protein synthesis and adjust to environmental barriers. Here, we focus on the role of ISR signaling for driving cancer progression. We highlight mechanisms of regulation for distinct mRNA translation downstream of the ISR, expand on oncogenic signaling utilizing the ISR in response to environmental stresses, and pinpoint the impact this has for cancer cell plasticity during resistance to therapy. There is an ongoing need for innovative drug targets in cancer treatment, and modulating ISR activity may provide a unique avenue for clinical benefit.
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Affiliation(s)
| | | | | | - Crystal S. Conn
- Department of Radiation Oncology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, United States
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25
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Batjargal T, Zappa F, Grant RJ, Piscopio RA, Chialastri A, Dey SS, Acosta-Alvear D, Wilson MZ. Optogenetic control of the integrated stress response reveals proportional encoding and the stress memory landscape. Cell Syst 2023; 14:551-562.e5. [PMID: 37473728 DOI: 10.1016/j.cels.2023.06.001] [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: 06/13/2022] [Revised: 12/27/2022] [Accepted: 06/09/2023] [Indexed: 07/22/2023]
Abstract
The integrated stress response (ISR) is a conserved signaling network that detects aberrations and computes cellular responses. Dissecting these computations has been difficult because physical and chemical inducers of stress activate multiple parallel pathways. To overcome this challenge, we engineered a photo-switchable control over the ISR sensor kinase PKR (opto-PKR), enabling virtual, on-target activation. Using light to control opto-PKR dynamics, we traced information flow through the transcriptome and for key downstream ISR effectors. Our analyses revealed a biphasic, proportional transcriptional response with two dynamic modes, transient and gradual, that correspond to adaptive and terminal outcomes. We then constructed an ordinary differential equation (ODE) model of the ISR, which demonstrated the dependence of future stress responses on past stress. Finally, we tested our model using high-throughput light-delivery to map the stress memory landscape. Our results demonstrate that cells encode information in stress levels, durations, and the timing between encounters. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Taivan Batjargal
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Francesca Zappa
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Ryan J Grant
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Robert A Piscopio
- Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Alex Chialastri
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Siddharth S Dey
- Center for BioEngineering, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Diego Acosta-Alvear
- Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA.
| | - Maxwell Z Wilson
- Center for BioEngineering, University of California Santa Barbara, Santa Barbara, CA, USA; Biomolecular Science and Engineering Program, University of California Santa Barbara, Santa Barbara, CA, USA; Department of Molecular, Cellular, and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA, USA; Neuroscience Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA.
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26
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Bourhill T, Rohani L, Kumar M, Bose P, Rancourt D, Johnston RN. Modulation of Reoviral Cytolysis (II): Cellular Stemness. Viruses 2023; 15:1473. [PMID: 37515162 PMCID: PMC10386201 DOI: 10.3390/v15071473] [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: 06/05/2023] [Revised: 06/21/2023] [Accepted: 06/25/2023] [Indexed: 07/30/2023] Open
Abstract
Oncolytic viruses (OVs) are an emerging cancer therapeutic that are intended to act by selectively targeting and lysing cancerous cells and by stimulating anti-tumour immune responses, while leaving normal cells mainly unaffected. Reovirus is a well-studied OV that is undergoing advanced clinical trials and has received FDA approval in selected circumstances. However, the mechanisms governing reoviral selectivity are not well characterised despite many years of effort, including those in our accompanying paper where we characterize pathways that do not consistently modulate reoviral cytolysis. We have earlier shown that reovirus is capable of infecting and lysing both certain types of cancer cells and also cancer stem cells, and here we demonstrate its ability to also infect and kill healthy pluripotent stem cells (PSCs). This led us to hypothesize that pathways responsible for stemness may constitute a novel route for the modulation of reoviral tropism. We find that reovirus is capable of killing both murine and human embryonic and induced pluripotent stem cells. Differentiation of PSCs alters the cells' reoviral-permissive state to a resistant one. In a breast cancer cell line that was resistant to reoviral oncolysis, induction of pluripotency programming rendered the cells permissive to cytolysis. Bioinformatic analysis indicates that expression of the Yamanaka pluripotency factors may be associated with regulating reoviral selectivity. Mechanistic insights from these studies will be useful for the advancement of reoviral oncolytic therapy.
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Affiliation(s)
- Tarryn Bourhill
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Leili Rohani
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Mehul Kumar
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Pinaki Bose
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Derrick Rancourt
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Randal N Johnston
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada
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Wang H, Li N, Li H, Zhang S, Zhang X, Yan X, Wang Z, Yang Y, Zhang S. Overexpression of NtGCN2 improves drought tolerance in tobacco by regulating proline accumulation, ROS scavenging ability, and stomatal closure. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 198:107665. [PMID: 37018865 DOI: 10.1016/j.plaphy.2023.107665] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/18/2023] [Accepted: 03/23/2023] [Indexed: 05/07/2023]
Abstract
Drought stress is a severe threat to plants. Genes that respond to drought stress are essential for plant growth and development. General control nonderepressible 2 (GCN2) encodes a protein kinase that responds to various biotic and abiotic stresses. However, the mechanism of GCN2 in plant drought tolerance remains unclear. In the present study, the promoters of NtGCN2 from Nicotiana tabacum K326, which contained a drought-responsive Cis-acting element MYB that can be activated by drought stress, were cloned. Furthermore, the drought tolerance function of NtGCN2 was investigated using NtGCN2-overexpressed transgenic tobacco plants. NtGCN2-overexpressed transgenic plants were more tolerant to drought stress than wild-type (WT) plants. The transgenic tobacco plants exhibited higher proline and abscisic acid (ABA) contents, antioxidant enzyme activities, leaf relative water content, and expression levels of genes encoding key antioxidant enzymes and proline synthase, but lower levels of malondialdehyde and reactive oxygen species, and reduced stomatal apertures, stomatal densities, and stomatal opening rates compared to WT plants under drought stress. These results indicated that overexpression of NtGCN2 conferred drought tolerance in transgenic tobacco plants. RNA-seq analysis showed that overexpression of NtGCN2 responded to drought stress by regulating the expression of genes related to proline synthesis and catabolism, abscisic acid synthesis and catabolism, antioxidant enzymes, and ion channels in guard cells. These results showed that NtGCN2 might regulate drought tolerance by regulating proline accumulation, reactive oxygen species (ROS) scavenging, and stomatal closure in tobacco and may have the potential for application in the genetic modification of crop drought tolerance.
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Affiliation(s)
- Hao Wang
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China
| | - Ning Li
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China
| | - Hang Li
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China
| | - Songjie Zhang
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China
| | - Xiaoquan Zhang
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China
| | - Xiaoxiao Yan
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China
| | - Zhaojun Wang
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China
| | - Yongxia Yang
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China
| | - Songtao Zhang
- National Tobacco Cultivation & Physiology & Biochemistry Research Centre, College of Tobacco Science, Henan Agricultural University, Zhengzhou, 450002, Henan, China.
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28
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Nolin SJ, Taylor RL, Edens FW, Siegel PB, Ashwell CM. Combining supervised machine learning with statistics reveals differential gene expression patterns related to energy metabolism in the jejuna of chickens divergently selected for antibody response to sheep red blood cells. Poult Sci 2023; 102:102751. [PMID: 37244088 DOI: 10.1016/j.psj.2023.102751] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 04/19/2023] [Accepted: 04/23/2023] [Indexed: 05/29/2023] Open
Abstract
Since the 1970s, 2 lines of White Leghorn chickens, HAS and LAS, have been continuously divergently selected for 5-day postinjection antibody titer to injection with sheep red blood cells (SRBC). Antibody response is a complex genetic trait and characterizing differences in gene expression could facilitate better understanding of physiological changes due to selection and antigen exposure. At 41 d of age, randomly selected HAS and LAS chickens, which had been coraised from hatch, were either injected with SRBC (HASI and LASI) or kept as the noninjected cohort (HASN and LASN). Five days later, all were euthanized, and samples collected from the jejunum for RNA isolation and sequencing. Resulting gene expression data were analyzed combining traditional statistics with machine learning to obtain signature gene lists for functional analysis. Differences in ATP production and cellular processes were observed in the jejunum between lines and following SRBC injection. HASN vs. LASN exhibited upregulation of ATP production, immune cell motility, and inflammation. LASI exhibits upregulation of ATP production and protein synthesis vs. LASN, reflective of what was observed in HASN vs. LASN. In contrast, no corresponding upregulation of ATP production was observed in HASI vs. HASN, and most other cellular processes appear inhibited. Without exposure to SRBC, gene expression in the jejunum indicates HAS generates more ATP than LAS, suggesting HAS maintains a "primed" system; and gene expression of HASI vs. HASN further suggests this basal ATP production is sufficient for robust antibody responses. Conversely, LASI vs. LASN jejunal gene expression implies a physiological need for increased ATP production with only minimal correlating antibody production. The results of this experiment provide insight into energetic resource needs and allocations in the jejunum in response to genetic selection and antigen exposure in HAS and LAS which may help explain phenotypic differences observed in antibody response.
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Affiliation(s)
- Shelly J Nolin
- Prestage Department of Poultry Science, North Carolina State University, Raleigh, NC 27695, USA.
| | - Robert L Taylor
- Davis College of Agriculture, Natural Resources, and Design, West Virginia University, Morgantown West, VA 26506-6108, USA
| | - Frank W Edens
- Prestage Department of Poultry Science, North Carolina State University, Raleigh, NC 27695, USA
| | - Paul B Siegel
- Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Christopher M Ashwell
- Davis College of Agriculture, Natural Resources, and Design, West Virginia University, Morgantown West, VA 26506-6108, USA
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29
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Gupta M, Walters B, Katsara O, Granados Blanco K, Geter P, Schneider R. eIF2Bδ blocks the integrated stress response and maintains eIF2B activity and cancer metastasis by overexpression in breast cancer stem cells. Proc Natl Acad Sci U S A 2023; 120:e2207898120. [PMID: 37014850 PMCID: PMC10104532 DOI: 10.1073/pnas.2207898120] [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: 05/06/2022] [Accepted: 03/08/2023] [Indexed: 04/05/2023] Open
Abstract
Breast cancer (BC) metastasis involves cancer stem cells (CSCs) and their regulation by micro-RNAs (miRs), but miR targeting of the translation machinery in CSCs is poorly explored. We therefore screened miR expression levels in a range of BC cell lines, comparing non-CSCs to CSCs, and focused on miRs that target translation and protein synthesis factors. We describe a unique translation regulatory axis enacted by reduced expression of miR-183 in breast CSCs, which we show targets the eIF2Bδ subunit of guanine nucleotide exchange factor eIF2B, a regulator of protein synthesis and the integrated stress response (ISR) pathway. We report that reduced expression of miR-183 greatly increases eIF2Bδ protein levels, preventing strong induction of the ISR and eIF2α phosphorylation, by preferential interaction with P-eIF2α. eIF2Bδ overexpression is essential for BC cell invasion, metastasis, maintenance of metastases, and breast CSC expansion in animal models. Increased expression of eIF2Bδ, a site of action of the drug ISRIB that also prevents ISR signaling, is essential for breast CSC maintenance and metastatic capacity.
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Affiliation(s)
- Malavika Gupta
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY10016
| | - Beth A. Walters
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY10016
| | - Olga Katsara
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY10016
| | - Karol Granados Blanco
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY10016
| | - Phillip A. Geter
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY10016
| | - Robert J. Schneider
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY10016
- New York University Perlmutter Cancer Center, New York University Grossman School of Medicine, New York, NY10016
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30
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Carlson KR, Georgiadis MM, Tameire F, Staschke KA, Wek RC. Activation of Gcn2 by small molecules designed to be inhibitors. J Biol Chem 2023; 299:104595. [PMID: 36898579 PMCID: PMC10124904 DOI: 10.1016/j.jbc.2023.104595] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 03/06/2023] [Indexed: 03/10/2023] Open
Abstract
The integrated stress response (ISR) is an important mechanism by which cells confer protection against environmental stresses. Central to the ISR is a collection of related protein kinases that monitor stress conditions, such as Gcn2 (EIF2AK4) that recognizes nutrient limitations, inducing phosphorylation of eukaryotic translation initiation factor 2 (eIF2). Gcn2 phosphorylation of eIF2 lowers bulk protein synthesis, conserving energy and nutrients, coincident with preferential translation of stress-adaptive gene transcripts, such as that encoding the Atf4 transcriptional regulator. While Gcn2 is central for cell protection to nutrient stress and its depletion in humans leads to pulmonary disorders, Gcn2 can also contribute to the progression of cancers and facilitate neurological disorders during chronic stress. Consequently, specific ATP-competitive inhibitors of Gcn2 protein kinase have been developed. In this study, we report that one such Gcn2 inhibitor, Gcn2iB, can activate Gcn2, and we probe the mechanism by which this activation occurs. Low concentrations of Gcn2iB increase Gcn2 phosphorylation of eIF2 and enhance Atf4 expression and activity. Of importance, Gcn2iB can activate Gcn2 mutants devoid of functional regulatory domains or with certain kinase domain substitutions derived from Gcn2-deficient human patients. Other ATP-competitive inhibitors can also activate Gcn2, although there are differences in their mechanisms of activation. These results provide a cautionary note about the pharmacodynamics of eIF2 kinase inhibitors in therapeutic applications. Compounds designed to be kinase inhibitors that instead directly activate Gcn2, even loss of function variants, may provide tools to alleviate deficiencies in Gcn2 and other regulators of the ISR.
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Affiliation(s)
- Kenneth R Carlson
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Millie M Georgiadis
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
| | | | - Kirk A Staschke
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
| | - Ronald C Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA; Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA.
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31
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Insights into the mechanism of oligodendrocyte protection and remyelination enhancement by the integrated stress response. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.23.525156. [PMID: 36747743 PMCID: PMC9900777 DOI: 10.1101/2023.01.23.525156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
CNS inflammation triggers activation of the integrated stress response (ISR). We previously reported that prolonging the ISR protects remyelinating oligodendrocytes and promotes remyelination in the presence of inflammation (Chen et al., eLife , 2021). However, the exact mechanisms through which this occurs remain unknown. Here, we investigated whether the ISR modulator Sephin1 in combination with the oligodendrocyte differentiation enhancing reagent bazedoxifene (BZA) is able to accelerate remyelination under inflammation, and the underlying mechanisms mediating this pathway. We find that the combined treatment of Sephin1 and BZA is sufficient to accelerate early-stage remyelination in mice with ectopic IFN-γ expression in the CNS. IFN-γ, which is a critical inflammatory cytokine in multiple sclerosis (MS), inhibits oligodendrocyte precursor cell (OPC) differentiation in culture and triggers a mild ISR. Mechanistically, we further show that BZA promotes OPC differentiation in the presence of IFN-γ, while Sephin1 enhances the IFN-γ-induced ISR by reducing protein synthesis and increasing RNA stress granule formation in differentiating oligodendrocytes. Finally, the ISR suppressor 2BAct is able to partially lessen the beneficial effect of Sephin1 on disease progression, in an MS mouse model of experimental autoimmune encephalitis (EAE). Overall, our findings uncover distinct mechanisms of action of BZA and Sephin1 on oligodendrocyte lineage cells under inflammatory stress, suggesting that a combination therapy may effectively promote restoring neuronal function in MS patients.
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32
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Yang H, Chen T, Denoyelle S, Chen L, Fan J, Zhang Y, Halperin JA, Chorev M, Aktas BH. Role of symmetry in 3,3-diphenyl-1,3-dihydroindol-2-one derivatives as inhibitors of translation initiation. Bioorg Med Chem Lett 2023; 80:129119. [PMID: 36581302 PMCID: PMC9922553 DOI: 10.1016/j.bmcl.2022.129119] [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: 10/04/2022] [Revised: 12/13/2022] [Accepted: 12/23/2022] [Indexed: 12/28/2022]
Abstract
The ternary complex (eIF2·GTP·Met-tRNAiMet) and the eIF4F complex assembly are two major regulatory steps in the eukaryotic translation initiation. Inhibition of the ternary complex assembly is therefore a promising target for the development of novel anti-cancer therapeutics. Building on the finding that clotrimazole (CLT), a molecular probe that depletes intracellular Ca2+ stores and subsequently induce eIF2α phosphorylation, inhibit translation initiation, and reduce preferentially the expression of oncoproteins over "housekeeping" ones,1-3 we undertook structure activity relationship (SAR) studies that identified 3,3-diarylindoline-2-one #1181 as an interesting scaffold. Compound #1181 also induce phosphorylation of eIF2α thereby reducing the availability of the ternary complex, which leads to inhibition of translation initiation.4 Our subsequent efforts focused on understanding SAR iterative lead optimization to enhance potency and improve bioavailability. Herein, we report a complementing study focusing on heavily substituted symmetric and asymmetric 3,3-(o,m-disubstituted)diarylindoline-2-ones. These compounds were evaluated by the dual luciferase reporter ternary complex assay that recapitualates phosphorylation of eIF2α in a quantitative manner. We also evaluated all compounds by sulforhodamine B assay, which measures the overall effect of compounds on cell proliferations and/or viability.
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Affiliation(s)
- Hongwei Yang
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA.
| | - Ting Chen
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA
| | - Séverine Denoyelle
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA
| | - Limo Chen
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA
| | - Jing Fan
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA
| | - Yingzhen Zhang
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA
| | - José A Halperin
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA; Harvard Medical School, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA
| | - Michael Chorev
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA; Harvard Medical School, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA.
| | - Bertal H Aktas
- Brigham and Women's Hospital, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA; Harvard Medical School, Division of Hematology, 4 Balckfan Circle. HIM 7, Boston, MA 02115, USA.
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PKR-Mediated Phosphorylation of eIF2a and CHK1 Is Associated with Doxorubicin-Mediated Apoptosis in HCC1143 Triple-Negative Breast Cancer Cells. Int J Mol Sci 2022; 23:ijms232415872. [PMID: 36555509 PMCID: PMC9779813 DOI: 10.3390/ijms232415872] [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: 11/06/2022] [Revised: 12/11/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022] Open
Abstract
Triple-negative breast cancer is more aggressive than other types of breast cancer. Protein kinase R (PKR), which is activated by dsRNA, is known to play a role in doxorubicin-mediated apoptosis; however, its role in DNA damage-mediated apoptosis is not well understood. In this study, we investigated the roles of PKR and its downstream players in doxorubicin-treated HCC1143 triple-negative breast cancer cells. Doxorubicin treatment induces DNA damage and apoptosis. Interestingly, doxorubicin treatment induced the phosphorylation of eukaryotic initiation factor 2 alpha (eIF2α) via PKR, whereas the inhibition of PKR with inhibitor C16 reduced eIF2α phosphorylation. Under these conditions, doxorubicin-mediated DNA fragmentation, cell death, and poly(ADP ribose) polymerase and caspase 7 levels were recovered. In addition, phosphorylation of checkpoint kinase 1 (CHK1), which is known to be involved in doxorubicin-mediated DNA damage, was increased by doxorubicin treatment, but blocked by PKR inhibition. Protein translation was downregulated by doxorubicin treatment and upregulated by blocking PKR phosphorylation. These results suggest that PKR activation induces apoptosis by increasing the phosphorylation of eIF2α and CHK1 and decreasing the global protein translation in doxorubicin-treated HCC1143 triple-negative breast cancer cells.
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Lokdarshi A, von Arnim AG. Review: Emerging roles of the signaling network of the protein kinase GCN2 in the plant stress response. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 320:111280. [PMID: 35643606 PMCID: PMC9197246 DOI: 10.1016/j.plantsci.2022.111280] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/07/2022] [Accepted: 03/30/2022] [Indexed: 06/15/2023]
Abstract
The pan-eukaryotic protein kinase GCN2 (General Control Nonderepressible2) regulates the translation of mRNAs in response to external and metabolic conditions. Although GCN2 and its substrate, translation initiation factor 2 (eIF2) α, and several partner proteins are substantially conserved in plants, this kinase has assumed novel functions in plants, including in innate immunity and retrograde signaling between the chloroplast and cytosol. How exactly some of the biochemical paradigms of the GCN2 system have diverged in the green plant lineage is only partially resolved. Specifically, conflicting data underscore and cast doubt on whether GCN2 regulates amino acid biosynthesis; also whether phosphorylation of eIF2α can in fact repress global translation or activate mRNA specific translation via upstream open reading frames; and whether GCN2 is controlled in vivo by the level of uncharged tRNA. This review examines the status of research on the eIF2α kinase, GCN2, its function in the response to xenobiotics, pathogens, and abiotic stress conditions, and its rather tenuous role in the translational control of mRNAs.
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Affiliation(s)
- Ansul Lokdarshi
- Department of Biology, Valdosta State University, Valdosta, GA 31698, USA.
| | - Albrecht G von Arnim
- Department of Biochemistry & Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN 37996-1939, USA; UT-ORNL Graduate School of Genome Science and Technology, The University of Tennessee, Knoxville, TN 37996-1939, USA.
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35
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Regulation and function of elF2B in neurological and metabolic disorders. Biosci Rep 2022; 42:231311. [PMID: 35579296 PMCID: PMC9208314 DOI: 10.1042/bsr20211699] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/28/2022] [Accepted: 05/12/2022] [Indexed: 11/27/2022] Open
Abstract
Eukaryotic initiation factor 2B, eIF2B is a guanine nucleotide exchange, factor with a central role in coordinating the initiation of translation. During stress and disease, the activity of eIF2B is inhibited via the phosphorylation of its substrate eIF2 (p-eIF2α). A number of different kinases respond to various stresses leading to the phosphorylation of the alpha subunit of eIF2, and collectively this regulation is known as the integrated stress response, ISR. This targeting of eIF2B allows the cell to regulate protein synthesis and reprogramme gene expression to restore homeostasis. Advances within structural biology have furthered our understanding of how eIF2B interacts with eIF2 in both the productive GEF active form and the non-productive eIF2α phosphorylated form. Here, current knowledge of the role of eIF2B in the ISR is discussed within the context of normal and disease states focusing particularly on diseases such as vanishing white matter disease (VWMD) and permanent neonatal diabetes mellitus (PNDM), which are directly linked to mutations in eIF2B. The role of eIF2B in synaptic plasticity and memory formation is also discussed. In addition, the cellular localisation of eIF2B is reviewed and considered along with the role of additional in vivo eIF2B binding factors and protein modifications that may play a role in modulating eIF2B activity during health and disease.
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36
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Zheng X, Nie S, Feng WH. Regulation of antiviral immune response by African swine fever virus (ASFV). Virol Sin 2022; 37:157-167. [PMID: 35278697 PMCID: PMC9170969 DOI: 10.1016/j.virs.2022.03.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 03/07/2022] [Indexed: 12/13/2022] Open
Abstract
African swine fever (ASF) is a highly contagious and acute hemorrhagic viral disease with a high mortality approaching 100% in domestic pigs. ASF is an endemic in countries in sub-Saharan Africa. Now, it has been spreading to many countries, especially in Asia and Europe. Due to the fact that there is no commercial vaccine available for ASF to provide sustainable prevention, the disease has spread rapidly worldwide and caused great economic losses in swine industry. The knowledge gap of ASF virus (ASFV) pathogenesis and immune evasion is the main factor to limit the development of safe and effective ASF vaccines. Here, we will summarize the molecular mechanisms of how ASFV interferes with the host innate and adaptive immune responses. An in-depth understanding of ASFV immune evasion strategies will provide us with rational design of ASF vaccines.
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Affiliation(s)
- Xiaojie Zheng
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Shengming Nie
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Wen-Hai Feng
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China; Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
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37
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Gugliuzza MV, Crist C. Muscle stem cell adaptations to cellular and environmental stress. Skelet Muscle 2022; 12:5. [PMID: 35151369 PMCID: PMC8840228 DOI: 10.1186/s13395-022-00289-6] [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: 11/23/2021] [Accepted: 01/30/2022] [Indexed: 12/21/2022] Open
Abstract
Background Lifelong regeneration of the skeletal muscle is dependent on a rare population of resident skeletal muscle stem cells, also named ‘satellite cells’ for their anatomical position on the outside of the myofibre and underneath the basal lamina. Muscle stem cells maintain prolonged quiescence, but activate the myogenic programme and the cell cycle in response to injury to expand a population of myogenic progenitors required to regenerate muscle. The skeletal muscle does not regenerate in the absence of muscle stem cells. Main body The notion that lifelong regeneration of the muscle is dependent on a rare, non-redundant population of stem cells seems contradictory to accumulating evidence that muscle stem cells have activated multiple stress response pathways. For example, muscle stem cell quiescence is mediated in part by the eIF2α arm of the integrated stress response and by negative regulators of mTORC1, two translational control pathways that downregulate protein synthesis in response to stress. Muscle stem cells also activate pathways to protect against DNA damage, heat shock, and environmental stress. Here, we review accumulating evidence that muscle stem cells encounter stress during their prolonged quiescence and their activation. While stress response pathways are classically described to be bimodal whereby a threshold dictates cell survival versus cell death responses to stress, we review evidence that muscle stem cells additionally respond to stress by spontaneous activation and fusion to myofibres. Conclusion We propose a cellular stress test model whereby the prolonged state of quiescence and the microenvironment serve as selective pressures to maintain muscle stem cell fitness, to safeguard the lifelong regeneration of the muscle. Fit muscle stem cells that maintain robust stress responses are permitted to maintain the muscle stem cell pool. Unfit muscle stem cells are depleted from the pool first by spontaneous activation, or in the case of severe stress, by activating cell death or senescence pathways.
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38
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Sunavala-Dossabhoy G. Disorder at the Start: The Contribution of Dysregulated Translation Initiation to Cancer Therapy Resistance. FRONTIERS IN ORAL HEALTH 2022; 2:765931. [PMID: 35048066 PMCID: PMC8757695 DOI: 10.3389/froh.2021.765931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/02/2021] [Indexed: 11/26/2022] Open
Abstract
Translation of cellular RNA to protein is an energy-intensive process through which synthesized proteins dictate cellular processes and function. Translation is regulated in response to extracellular effectors and availability of amino acids intracellularly. Most eukaryotic mRNA rely on the methyl 7-guanosine (m7G) nucleotide cap to recruit the translation machinery, and the uncoupling of translational control that occurs in tumorigenesis plays a significant role in cancer treatment response. This article provides an overview of the mammalian translation initiation process and the primary mechanisms by which it is regulated. An outline of how deregulation of initiation supports tumorigenesis and how initiation at a downstream open reading frame (ORF) of Tousled-like kinase 1 (TLK1) leads to treatment resistance is discussed.
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Affiliation(s)
- Gulshan Sunavala-Dossabhoy
- Department of Biochemistry and Molecular Biology, Louisiana State University Health and Feist Weiller Cancer Center, Shreveport, LA, United States
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39
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Borrello MT, Martin MB, Pin CL. The unfolded protein response: An emerging therapeutic target for pancreatitis and pancreatic ductal adenocarcinoma. Pancreatology 2022; 22:148-159. [PMID: 34774415 DOI: 10.1016/j.pan.2021.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/23/2021] [Accepted: 10/25/2021] [Indexed: 12/11/2022]
Abstract
Pancreatitis is a debilitating disease involving inflammation and fibrosis of the exocrine pancreas. Recurrent or chronic forms of pancreatitis are a significant risk factor for pancreatic ductal adenocarcinoma. While genetic factors have been identified for both pathologies, environmental stresses play a large role in their etiology. All cells have adapted mechanisms to handle acute environmental stress that alters energy demands. A common pathway involved in the stress response involves endoplasmic reticulum stress and the unfolded protein response (UPR). While rapidly activated by many external stressors, in the pancreas the UPR plays a fundamental biological role, likely due to the high protein demands in acinar cells. Despite this, increased UPR activity is observed in response to acute injury or following exposure to risk factors associated with pancreatitis and pancreatic cancer. Studies in animal and cell cultures models show the importance of affecting the UPR in the context of both diseases, and inhibitors have been developed for several specific mediators of the UPR. Given the importance of the UPR to normal acinar cell function, efforts to affect the UPR in the context of disease must be able to specifically target pathology vs. physiology. In this review, we highlight the importance of the UPR to normal and pathological conditions of the exocrine pancreas. We discuss recent studies suggesting the UPR may be involved in the initiation and progression of pancreatitis and PDAC, as well as contributing to chemoresistance that occurs in pancreatic cancer. Finally, we discuss the potential of targeting the UPR for treatment.
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Affiliation(s)
- M Teresa Borrello
- Newcastle Fibrosis Research Group, Biosciences Institute, Newcastle University, Newcastle Upon Tyne, UK
| | - Mickenzie B Martin
- Depts. of Physiology and Pharmacology, Paediatrics, and Oncology, Schulich School of Medicine and Dentistry, The University of Western Ontario, Canada; Children's Health Research Institute, Lawson Health Research Institute, London, Ontario, Canada
| | - Christopher L Pin
- Depts. of Physiology and Pharmacology, Paediatrics, and Oncology, Schulich School of Medicine and Dentistry, The University of Western Ontario, Canada; Children's Health Research Institute, Lawson Health Research Institute, London, Ontario, Canada.
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40
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Charif SE, Vassallu MF, Salvañal L, Igaz LM. Protein synthesis modulation as a therapeutic approach for amyotrophic lateral sclerosis and frontotemporal dementia. Neural Regen Res 2021; 17:1423-1430. [PMID: 34916412 PMCID: PMC8771112 DOI: 10.4103/1673-5374.330593] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Protein synthesis is essential for cells to perform life metabolic processes. Pathological alterations of protein content can lead to particular diseases. Cells have an intrinsic array of mechanisms and pathways that are activated when protein misfolding, accumulation, aggregation or mislocalization occur. Some of them (like the unfolded protein response) represent complex interactions between endoplasmic reticulum sensors and elongation factors that tend to increase expression of chaperone proteins and/or repress translation in order to restore protein homeostasis (also known as proteostasis). This is even more important in neurons, as they are very susceptible to harmful effects associated with protein overload and proteostatic mechanisms are less effective with age. Several neurodegenerative pathologies such as Alzheimer's, Parkinson's, and Huntington's diseases, amyotrophic lateral sclerosis and frontotemporal dementia exhibit a particular molecular signature of distinct, unbalanced protein overload. In amyotrophic lateral sclerosis and frontotemporal dementia, the majority of cases present intracellular inclusions of ubiquitinated transactive response DNA-binding protein of 43 kDa (TDP-43). TDP-43 is an RNA binding protein that participates in RNA metabolism, among other functions. Dysregulation of TDP-43 (e.g. aggregation and mislocalization) can dramatically affect neurons, and this has been linked to disease development. Expression of amyotrophic lateral sclerosis/frontotemporal dementia TDP-43-related mutations in cellular and animal models has been shown to recapitulate key features of the amyotrophic lateral sclerosis/frontotemporal dementia disease spectrum. These variants can be causative of degeneration onset and progression. Most neurodegenerative diseases (including amyotrophic lateral sclerosis and frontotemporal dementia) have no cure at the moment; however, modulating translation has recently emerged as an attractive approach that can be performed at several steps (i.e. regulating activation of initiation and elongation factors, inhibiting unfolded protein response activation or inducing chaperone expression and activity). This review focuses on the features of protein imbalance in neurodegenerative disorders and the relevance of developing therapeutical compounds aiming at restoring proteostasis. We strive to highlight the importance of research on drugs that, not only restore protein imbalance without compromising translational activity of cells, but are also as safe as possible for the patients.
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Affiliation(s)
- Santiago E Charif
- IFIBIO Houssay, Grupo de Neurociencia de Sistemas, Facultad de Medicina, Universidad de Buenos Aires -CONICET, Buenos Aires, Argentina
| | - M Florencia Vassallu
- IFIBIO Houssay, Grupo de Neurociencia de Sistemas, Facultad de Medicina, Universidad de Buenos Aires -CONICET, Buenos Aires, Argentina
| | - Lara Salvañal
- IFIBIO Houssay, Grupo de Neurociencia de Sistemas, Facultad de Medicina, Universidad de Buenos Aires -CONICET, Buenos Aires, Argentina
| | - Lionel M Igaz
- IFIBIO Houssay, Grupo de Neurociencia de Sistemas, Facultad de Medicina, Universidad de Buenos Aires -CONICET, Buenos Aires, Argentina
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41
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Kershaw CJ, Jennings MD, Cortopassi F, Guaita M, Al-Ghafli H, Pavitt GD. GTP binding to translation factor eIF2B stimulates its guanine nucleotide exchange activity. iScience 2021; 24:103454. [PMID: 34877508 PMCID: PMC8633983 DOI: 10.1016/j.isci.2021.103454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/26/2021] [Accepted: 11/11/2021] [Indexed: 01/23/2023] Open
Abstract
eIF2B is the guanine nucleotide exchange factor (GEF) required for cytoplasmic protein synthesis initiation in eukaryotes and its regulation within the integrated stress response (ISR). It activates its partner factor eIF2, thereby promoting translation initiation. Here we provide evidence through biochemical and genetic approaches that eIF2B can bind directly to GTP and this can enhance its rate of GEF activity toward eIF2–GDP in vitro. GTP binds to a subcomplex of the eIF2Bγ and ε subunits. The eIF2Bγ amino-terminal domain shares structural homology with hexose sugar phosphate pyrophosphorylase enzymes that bind specific nucleotides. A K66R mutation in eIF2Bγ is especially sensitive to guanine or GTP in a range of functional assays. Taken together, our data suggest eIF2Bγ may act as a sensor of purine nucleotide availability and thus modulate eIF2B activity and protein synthesis in response to fluctuations in cellular nucleotide levels. eIF2B, the GDP exchange factor for eIF2 in translation and its control, binds GTP GTP binding enhances the rate of eIF2B GEF activity toward eIF2–GDP in vitro A K66R mutation in yeast eIF2Bγ is sensitive to guanine in vivo or GTP in vitro eIF2B may act as a sensor of purine nucleotide availability
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Affiliation(s)
- Christopher J Kershaw
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Martin D Jennings
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Francesco Cortopassi
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Margherita Guaita
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Hawra Al-Ghafli
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Graham D Pavitt
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
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42
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Sahin GS, Lee H, Engin F. An accomplice more than a mere victim: The impact of β-cell ER stress on type 1 diabetes pathogenesis. Mol Metab 2021; 54:101365. [PMID: 34728341 PMCID: PMC8606542 DOI: 10.1016/j.molmet.2021.101365] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/23/2021] [Accepted: 10/26/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Pancreatic β-cells are the insulin factory of an organism with a mission to regulate glucose homeostasis in the body. Due to their high secretory activity, β-cells rely on a functional and intact endoplasmic reticulum (ER). Perturbations to ER homeostasis and unmitigated stress lead to β-cell dysfunction and death. Type 1 diabetes (T1D) is a chronic inflammatory disease caused by the autoimmune-mediated destruction of β-cells. Although autoimmunity is an essential component of T1D pathogenesis, accumulating evidence suggests an important role of β-cell ER stress and aberrant unfolded protein response (UPR) in disease initiation and progression. SCOPE OF REVIEW In this article, we introduce ER stress and the UPR, review β-cell ER stress in various mouse models, evaluate its involvement in inflammation, and discuss the effects of ER stress on β-cell plasticity and demise, and islet autoimmunity in T1D. We also highlight the relationship of ER stress with other stress response pathways and provide insight into ongoing clinical studies targeting ER stress and the UPR for the prevention or treatment of T1D. MAJOR CONCLUSIONS Evidence from ex vivo studies, in vivo mouse models, and tissue samples from patients suggest that β-cell ER stress and a defective UPR contribute to T1D pathogenesis. Thus, restoration of β-cell ER homeostasis at various stages of disease presents a plausible therapeutic strategy for T1D. Identifying the specific functions and regulation of each UPR sensor in β-cells and uncovering the crosstalk between stressed β-cells and immune cells during T1D progression would provide a better understanding of the molecular mechanisms of disease process, and may reveal novel targets for development of effective therapies for T1D.
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Affiliation(s)
- Gulcan Semra Sahin
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, 53706, USA
| | - Hugo Lee
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, 53706, USA
| | - Feyza Engin
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, 53706, USA; Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, 53705, USA; Department of Cell & Regenerative Biology, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, 53705, USA.
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43
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Circir A, Koksal Bicakci G, Savas B, Doken DN, Henden ŞO, Can T, Karaca E, Erson-Bensan AE. A C-term truncated EIF2Bγ protein encoded by an intronically polyadenylated isoform introduces unfavorable EIF2Bγ-EIF2γ interactions. Proteins 2021; 90:889-897. [PMID: 34796993 DOI: 10.1002/prot.26284] [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: 08/16/2021] [Revised: 11/01/2021] [Accepted: 11/15/2021] [Indexed: 11/11/2022]
Abstract
Eukaryotic translation initiates upon recruitment of the EIF2-GTP·Met-tRNAi ternary complex (TC) to the ribosomes. EIF2 (α, β, γ subunits) is a GTPase. The GDP to GTP exchange within EIF2 is facilitated by the guanine nucleotide exchange factor EIF2B (α-ε subunits). During stress-induced conditions, phosphorylation of the α-subunit of EIF2 turns EIF2 into an inhibitor of EIF2B. In turn, inhibition of EIF2B decreases TC formation and triggers the internal stress response (ISR), which determines the cell fate. Deregulated ISR has been linked to neurodegenerative disorders and cancer, positioning EIF2B as a promising therapeutic target. Hence, a better understanding of the mechanisms/factors that regulate EIF2B activity is required. Here, combining transcript and protein level analyses, we describe an intronically polyadenylated (IPA) transcript of EIF2B's γ-subunit. We show that the IPA mRNA isoform is translated into a C-terminus truncated protein. Using structural modeling, we predict that the truncated EIF2Bγ protein has unfavorable interactions with EIF2γ, leading to a potential decrease in the stability of the nonproductive EIF2:EIF2B complex. While we discovered and confirmed the IPA mRNA isoform in breast cancer cells, the expression of this isoform is not cancer-specific and is widely present in normal tissues. Overall, our data show that a truncated EIF2Bγ protein co-exists with the canonical protein and is an additional player to regulate the equilibrium between productive and nonproductive states of the EIF2:EIF2B complex. These results may have implications in stress-induced translation control in normal and disease states. Our combinatorial approach demonstrates the need to study noncanonical mRNA and protein isoforms to understand protein interactions and intricate molecular mechanisms.
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Affiliation(s)
- Ayca Circir
- Department of Biological Sciences, Middle East Technical University (METU), Ankara, Turkey
| | - Gozde Koksal Bicakci
- Department of Biological Sciences, Middle East Technical University (METU), Ankara, Turkey
| | - Busra Savas
- Izmir Biomedicine and Genome Center, Balcova, Izmir, Turkey.,Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, Balcova, Izmir, Turkey
| | - Didem Naz Doken
- Department of Biological Sciences, Middle East Technical University (METU), Ankara, Turkey
| | - Şevki Onur Henden
- Department of Computer Engineering, Middle East Technical University (METU), Ankara, Turkey
| | - Tolga Can
- Department of Computer Engineering, Middle East Technical University (METU), Ankara, Turkey.,Cancer System Biology Laboratory (CanSyL), Graduate School of Informatics, Middle East Technical University (METU), Ankara, Turkey
| | - Ezgi Karaca
- Izmir Biomedicine and Genome Center, Balcova, Izmir, Turkey.,Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, Balcova, Izmir, Turkey
| | - Ayse Elif Erson-Bensan
- Department of Biological Sciences, Middle East Technical University (METU), Ankara, Turkey.,Cancer System Biology Laboratory (CanSyL), Graduate School of Informatics, Middle East Technical University (METU), Ankara, Turkey
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44
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Park J, Park J, Lee J, Lim C. The trinity of ribosome-associated quality control and stress signaling for proteostasis and neuronal physiology. BMB Rep 2021. [PMID: 34488933 PMCID: PMC8505234 DOI: 10.5483/bmbrep.2021.54.9.097] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Translating ribosomes accompany co-translational regulation of nascent polypeptide chains, including subcellular targeting, protein folding, and covalent modifications. Ribosome-associated quality control (RQC) is a co-translational surveillance mechanism triggered by ribosomal collisions, an indication of atypical translation. The ribosome-associated E3 ligase ZNF598 ubiquitinates small subunit proteins at the stalled ribosomes. A series of RQC factors are then recruited to dissociate and triage aberrant translation intermediates. Regulatory ribosomal stalling may occur on endogenous transcripts for quality gene expression, whereas ribosomal collisions are more globally induced by ribotoxic stressors such as translation inhibitors, ribotoxins, and UV radiation. The latter are sensed by ribosome-associated kinases GCN2 and ZAKα, activating integrated stress response (ISR) and ribotoxic stress response (RSR), respectively. Hierarchical crosstalks among RQC, ISR, and RSR pathways are readily detectable since the collided ribosome is their common substrate for activation. Given the strong implications of RQC factors in neuronal physiology and neurological disorders, the interplay between RQC and ribosome-associated stress signaling may sustain proteostasis, adaptively determine cell fate, and contribute to neural pathogenesis. The elucidation of underlying molecular principles in relevant human diseases should thus provide unexplored therapeutic opportunities.
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Affiliation(s)
- Jumin Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Jongmin Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Jongbin Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Chunghun Lim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
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45
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Maurano M, Snyder JM, Connelly C, Henao-Mejia J, Sidrauski C, Stetson DB. Protein kinase R and the integrated stress response drive immunopathology caused by mutations in the RNA deaminase ADAR1. Immunity 2021; 54:1948-1960.e5. [PMID: 34343497 DOI: 10.1016/j.immuni.2021.07.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/18/2021] [Accepted: 06/30/2021] [Indexed: 10/20/2022]
Abstract
The RNA deaminase ADAR1 is an essential negative regulator of the RNA sensor MDA5, and loss of ADAR1 function triggers inappropriate activation of MDA5 by self-RNAs. Mutations in ADAR, the gene that encodes ADAR1, cause human immune diseases, including Aicardi-Goutières syndrome (AGS). However, the mechanisms of MDA5-dependent disease pathogenesis in vivo remain unknown. Here we generated mice with a single amino acid change in ADAR1 that models the most common human ADAR AGS mutation. These Adar mutant mice developed lethal disease that required MDA5, the RIG-I-like receptor LGP2, type I interferons, and the eIF2α kinase PKR. A small-molecule inhibitor of the integrated stress response (ISR) that acts downstream of eIF2α phosphorylation prevented immunopathology and rescued the mice from mortality. These findings place PKR and the ISR as central components of immunopathology in vivo and identify therapeutic targets for treatment of human diseases associated with the ADAR1-MDA5 axis.
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Affiliation(s)
- Megan Maurano
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA; Medical Scientist Training Program, University of Washington School of Medicine, Seattle, WA 98195, USA; Molecular and Cellular Biology Graduate Program, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
| | | | - Jorge Henao-Mejia
- Department of Pathology and Laboratory Medicine, Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Division of Protective Immunity, Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104
| | | | - Daniel B Stetson
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA.
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46
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Bhingarkar A, Vangapandu HV, Rathod S, Hoshitsuki K, Fernandez CA. Amino Acid Metabolic Vulnerabilities in Acute and Chronic Myeloid Leukemias. Front Oncol 2021; 11:694526. [PMID: 34277440 PMCID: PMC8281237 DOI: 10.3389/fonc.2021.694526] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 06/15/2021] [Indexed: 12/24/2022] Open
Abstract
Amino acid (AA) metabolism plays an important role in many cellular processes including energy production, immune function, and purine and pyrimidine synthesis. Cancer cells therefore require increased AA uptake and undergo metabolic reprogramming to satisfy the energy demand associated with their rapid proliferation. Like many other cancers, myeloid leukemias are vulnerable to specific therapeutic strategies targeting metabolic dependencies. Herein, our review provides a comprehensive overview and TCGA data analysis of biosynthetic enzymes required for non-essential AA synthesis and their dysregulation in myeloid leukemias. Furthermore, we discuss the role of the general control nonderepressible 2 (GCN2) and-mammalian target of rapamycin (mTOR) pathways of AA sensing on metabolic vulnerability and drug resistance.
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Affiliation(s)
- Aboli Bhingarkar
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA, United States
| | - Hima V. Vangapandu
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA, United States
| | - Sanjay Rathod
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA, United States
| | - Keito Hoshitsuki
- Division of General Internal Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Christian A. Fernandez
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA, United States
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Hao Q, Heo JM, Nocek BP, Hicks KG, Stoll VS, Remarcik C, Hackett S, LeBon L, Jain R, Eaton D, Rutter J, Wong YL, Sidrauski C. Sugar phosphate activation of the stress sensor eIF2B. Nat Commun 2021; 12:3440. [PMID: 34103529 PMCID: PMC8187479 DOI: 10.1038/s41467-021-23836-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 05/19/2021] [Indexed: 02/07/2023] Open
Abstract
The multi-subunit translation initiation factor eIF2B is a control node for protein synthesis. eIF2B activity is canonically modulated through stress-responsive phosphorylation of its substrate eIF2. The eIF2B regulatory subcomplex is evolutionarily related to sugar-metabolizing enzymes, but the biological relevance of this relationship was unknown. To identify natural ligands that might regulate eIF2B, we conduct unbiased binding- and activity-based screens followed by structural studies. We find that sugar phosphates occupy the ancestral catalytic site in the eIF2Bα subunit, promote eIF2B holoenzyme formation and enhance enzymatic activity towards eIF2. A mutant in the eIF2Bα ligand pocket that causes Vanishing White Matter disease fails to engage and is not stimulated by sugar phosphates. These data underscore the importance of allosteric metabolite modulation for proper eIF2B function. We propose that eIF2B evolved to couple nutrient status via sugar phosphate sensing with the rate of protein synthesis, one of the most energetically costly cellular processes. The activity of translation initiation factor eIF2B is known to be modulated through stress-responsive phosphorylation of its substrate eIF2. Here, the authors uncover the regulation of eIF2B by the binding of sugar phosphates, suggesting a link between nutrient status and the rate of protein synthesis.
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Affiliation(s)
- Qi Hao
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Jin-Mi Heo
- Calico Life Sciences LLC, South San Francisco, CA, USA.,Loxo Oncology at Lilly, South San Francisco, CA, USA
| | | | - Kevin G Hicks
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | | | | | - Sean Hackett
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Lauren LeBon
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Rinku Jain
- Research & Development, AbbVie, North Chicago, IL, USA
| | - Dan Eaton
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Jared Rutter
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA.,Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT, USA
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Global phosphoproteomics pinpoints uncharted Gcn2-mediated mechanisms of translational control. Mol Cell 2021; 81:1879-1889.e6. [PMID: 33743194 DOI: 10.1016/j.molcel.2021.02.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/09/2020] [Accepted: 02/24/2021] [Indexed: 01/04/2023]
Abstract
The conserved Gcn2 protein kinase mediates cellular adaptations to amino acid limitation through translational control of gene expression that is exclusively executed by phosphorylation of the α-subunit of the eukaryotic translation initiation factor 2 (eIF2α). Using quantitative phosphoproteomics, however, we discovered that Gcn2 targets auxiliary effectors to modulate translation. Accordingly, Gcn2 also phosphorylates the β-subunit of the trimeric eIF2 G protein complex to promote its association with eIF5, which prevents spontaneous nucleotide exchange on eIF2 and thereby restricts the recycling of the initiator methionyl-tRNA-bound eIF2-GDP ternary complex in amino-acid-starved cells. This mechanism contributes to the inhibition of translation initiation in parallel to the sequestration of the nucleotide exchange factor eIF2B by phosphorylated eIF2α. Gcn2 further phosphorylates Gcn20 to antagonize, in an inhibitory feedback loop, the formation of the Gcn2-stimulatory Gcn1-Gcn20 complex. Thus, Gcn2 plays a substantially more intricate role in controlling translation initiation than hitherto appreciated.
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Schmitz A, Pinheiro Marques J, Oertig I, Maharjan N, Saxena S. Emerging Perspectives on Dipeptide Repeat Proteins in C9ORF72 ALS/FTD. Front Cell Neurosci 2021; 15:637548. [PMID: 33679328 PMCID: PMC7930069 DOI: 10.3389/fncel.2021.637548] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 01/07/2021] [Indexed: 11/13/2022] Open
Abstract
The most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is a hexanucleotide expansion in the chromosome 9 open reading frame 72 gene (C9ORF72). This hexanucleotide expansion consists of GGGGCC (G4C2) repeats that have been implicated to lead to three main modes of disease pathology: loss of function of the C9ORF72 protein, the generation of RNA foci, and the production of dipeptide repeat proteins (DPRs) through repeat-associated non-AUG (RAN) translation. Five different DPRs are currently known to be formed: glycine-alanine (GA) and glycine-arginine (GR) from the sense strand, proline-alanine (PA), and proline-arginine (PR) from the antisense strand, and glycine-proline (GP) from both strands. The exact contribution of each DPR to disease pathology is currently under intense scrutiny and is still poorly understood. However, recent advances in both neuropathological and cellular studies have provided us with clues enabling us to better understand the effect of individual DPRs on disease pathogenesis. In this review, we compile the current knowledge of specific DPR involvement on disease development and highlight recent advances, such as the impact of arginine-rich DPRs on nucleolar protein quality control, the correlation of poly-GR with neurodegeneration, and the possible involvement of chimeric DPR species. Further, we discuss recent findings regarding the mechanisms of RAN translation, its modulators, and other promising therapeutic options.
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Affiliation(s)
- Alexander Schmitz
- Department of Neurology, Center for Experimental Neurology, Inselspital University Hospital, Bern, Switzerland
- Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - João Pinheiro Marques
- Department of Neurology, Center for Experimental Neurology, Inselspital University Hospital, Bern, Switzerland
- Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Irina Oertig
- Department of Neurology, Center for Experimental Neurology, Inselspital University Hospital, Bern, Switzerland
- Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Niran Maharjan
- Department of Neurology, Center for Experimental Neurology, Inselspital University Hospital, Bern, Switzerland
- Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Smita Saxena
- Department of Neurology, Center for Experimental Neurology, Inselspital University Hospital, Bern, Switzerland
- Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
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50
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Rosche KL, Sidak-Loftis LC, Hurtado J, Fisk EA, Shaw DK. Arthropods Under Pressure: Stress Responses and Immunity at the Pathogen-Vector Interface. Front Immunol 2021; 11:629777. [PMID: 33659000 PMCID: PMC7917218 DOI: 10.3389/fimmu.2020.629777] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 12/30/2020] [Indexed: 12/14/2022] Open
Abstract
Understanding what influences the ability of some arthropods to harbor and transmit pathogens may be key for controlling the spread of vector-borne diseases. Arthropod immunity has a central role in dictating vector competence for pathogen acquisition and transmission. Microbial infection elicits immune responses and imparts stress on the host by causing physical damage and nutrient deprivation, which triggers evolutionarily conserved stress response pathways aimed at restoring cellular homeostasis. Recent studies increasingly recognize that eukaryotic stress responses and innate immunity are closely intertwined. Herein, we describe two well-characterized and evolutionarily conserved mechanisms, the Unfolded Protein Response (UPR) and the Integrated Stress Response (ISR), and examine evidence that these stress responses impact immune signaling. We then describe how multiple pathogens, including vector-borne microbes, interface with stress responses in mammals. Owing to the well-conserved nature of the UPR and ISR, we speculate that similar mechanisms may be occurring in arthropod vectors and ultimately impacting vector competence. We conclude this Perspective by positing that novel insights into vector competence will emerge when considering that stress-signaling pathways may be influencing the arthropod immune network.
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Affiliation(s)
- Kristin L Rosche
- Program in Vector-borne Disease, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, United States
| | - Lindsay C Sidak-Loftis
- Program in Vector-borne Disease, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, United States
| | - Joanna Hurtado
- Program in Vector-borne Disease, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, United States
| | - Elizabeth A Fisk
- Program in Vector-borne Disease, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, United States
| | - Dana K Shaw
- Program in Vector-borne Disease, Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA, United States
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