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Magg V, Manetto A, Kopp K, Wu CC, Naghizadeh M, Lindner D, Eke L, Welsch J, Kallenberger SM, Schott J, Haucke V, Locker N, Stoecklin G, Ruggieri A. Turnover of PPP1R15A mRNA encoding GADD34 controls responsiveness and adaptation to cellular stress. Cell Rep 2024; 43:114069. [PMID: 38602876 DOI: 10.1016/j.celrep.2024.114069] [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: 05/25/2022] [Revised: 01/25/2024] [Accepted: 03/21/2024] [Indexed: 04/13/2024] Open
Abstract
The integrated stress response (ISR) is a key cellular signaling pathway activated by environmental alterations that represses protein synthesis to restore homeostasis. To prevent sustained damage, the ISR is counteracted by the upregulation of growth arrest and DNA damage-inducible 34 (GADD34), a stress-induced regulatory subunit of protein phosphatase 1 that mediates translation reactivation and stress recovery. Here, we uncover a novel ISR regulatory mechanism that post-transcriptionally controls the stability of PPP1R15A mRNA encoding GADD34. We establish that the 3' untranslated region of PPP1R15A mRNA contains an active AU-rich element (ARE) recognized by proteins of the ZFP36 family, promoting its rapid decay under normal conditions and stabilization for efficient expression of GADD34 in response to stress. We identify the tight temporal control of PPP1R15A mRNA turnover as a component of the transient ISR memory, which sets the threshold for cellular responsiveness and mediates adaptation to repeated stress conditions.
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Affiliation(s)
- Vera Magg
- Heidelberg University, Medical Faculty Heidelberg, Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, 69120 Heidelberg, Germany
| | - Alessandro Manetto
- Heidelberg University, Medical Faculty Heidelberg, Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, 69120 Heidelberg, Germany
| | - Katja Kopp
- Heidelberg University, Medical Faculty Heidelberg, Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, 69120 Heidelberg, Germany
| | - Chia Ching Wu
- Heidelberg University, Medical Faculty Heidelberg, Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, 69120 Heidelberg, Germany
| | - Mohsen Naghizadeh
- Heidelberg University, Medical Faculty Mannheim, Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3) and Mannheim Cancer Center (MCC), 68167 Mannheim, Germany
| | - Doris Lindner
- Heidelberg University, Medical Faculty Mannheim, Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3) and Mannheim Cancer Center (MCC), 68167 Mannheim, Germany
| | - Lucy Eke
- Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, UK
| | - Julia Welsch
- Heidelberg University, Medical Faculty Heidelberg, Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, 69120 Heidelberg, Germany
| | - Stefan M Kallenberger
- Digital Health Center, Berlin Institute of Health (BIH) and Charité, 10178 Berlin, Germany; Medical Oncology, National Center for Tumor Diseases, Heidelberg University, 69120 Heidelberg, Germany
| | - Johanna Schott
- Heidelberg University, Medical Faculty Mannheim, Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3) and Mannheim Cancer Center (MCC), 68167 Mannheim, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Germany; Freie Universität Berlin, Faculty of Biology, Chemistry, and Pharmacy, 14195 Berlin, Germany
| | - Nicolas Locker
- Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, UK; The Pirbright Institute, GU24 0NF Pirbright, UK
| | - Georg Stoecklin
- Heidelberg University, Medical Faculty Mannheim, Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3) and Mannheim Cancer Center (MCC), 68167 Mannheim, Germany; Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany.
| | - Alessia Ruggieri
- Heidelberg University, Medical Faculty Heidelberg, Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research, 69120 Heidelberg, Germany.
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Oliveira MM, Mohamed M, Elder MK, Banegas-Morales K, Mamcarz M, Lu EH, Golhan EAN, Navrange N, Chatterjee S, Abel T, Klann E. The integrated stress response effector GADD34 is repurposed by neurons to promote stimulus-induced translation. Cell Rep 2024; 43:113670. [PMID: 38219147 PMCID: PMC10964249 DOI: 10.1016/j.celrep.2023.113670] [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: 07/04/2023] [Revised: 10/11/2023] [Accepted: 12/26/2023] [Indexed: 01/16/2024] Open
Abstract
Neuronal protein synthesis is required for long-lasting plasticity and long-term memory consolidation. Dephosphorylation of eukaryotic initiation factor 2α is one of the key translational control events that is required to increase de novo protein synthesis that underlies long-lasting plasticity and memory consolidation. Here, we interrogate the molecular pathways of translational control that are triggered by neuronal stimulation with brain-derived neurotrophic factor (BDNF), which results in eukaryotic initiation factor 2α (eIF2α) dephosphorylation and increases in de novo protein synthesis. Primary rodent neurons exposed to BDNF display elevated translation of GADD34, which facilitates eIF2α dephosphorylation and subsequent de novo protein synthesis. Furthermore, GADD34 requires G-actin generated by cofilin to dephosphorylate eIF2α and enhance protein synthesis. Finally, GADD34 is required for BDNF-induced translation of synaptic plasticity-related proteins. Overall, we provide evidence that neurons repurpose GADD34, an effector of the integrated stress response, as an orchestrator of rapid increases in eIF2-dependent translation in response to plasticity-inducing stimuli.
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Affiliation(s)
| | - Muhaned Mohamed
- Center for Neural Science, New York University, New York, NY, USA
| | - Megan K Elder
- Center for Neural Science, New York University, New York, NY, USA
| | | | - Maggie Mamcarz
- Center for Neural Science, New York University, New York, NY, USA
| | - Emily H Lu
- Center for Neural Science, New York University, New York, NY, USA
| | - Ela A N Golhan
- Center for Neural Science, New York University, New York, NY, USA
| | - Nishika Navrange
- Center for Neural Science, New York University, New York, NY, USA
| | - Snehajyoti Chatterjee
- Department of Neuroscience and Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Ted Abel
- Department of Neuroscience and Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Eric Klann
- Center for Neural Science, New York University, New York, NY, USA; NYU Neuroscience Institute, New York University School of Medicine, New York, NY, USA.
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3
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Santinelli R, Benz N, Guellec J, Quinquis F, Kocas E, Thomas J, Montier T, Ka C, Luczka-Majérus E, Sage E, Férec C, Coraux C, Trouvé P. The Inhibition of the Membrane-Bound Transcription Factor Site-1 Protease (MBTP1) Alleviates the p.Phe508del-Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Defects in Cystic Fibrosis Cells. Cells 2024; 13:185. [PMID: 38247876 PMCID: PMC10814821 DOI: 10.3390/cells13020185] [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: 12/01/2023] [Revised: 12/27/2023] [Accepted: 01/11/2024] [Indexed: 01/23/2024] Open
Abstract
Cystic Fibrosis (CF) is present due to mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene, the most frequent variant being p.phe508del. The CFTR protein is a chloride (Cl-) channel which is defective and almost absent of cell membranes when the p.Phe508del mutation is present. The p.Phe508del-CFTR protein is retained in the endoplasmic reticulum (ER) and together with inflammation and infection triggers the Unfolded Protein Response (UPR). During the UPR, the Activating Transcription Factor 6 (ATF6) is activated with cleavage and then decreases the expression of p.Phe508del-CFTR. We have previously shown that the inhibition of the activation of ATF6 alleviates the p.Phe508del-CFTR defects in cells overexpressing the mutated protein. In the present paper, our aim was to inhibit the cleavage of ATF6, and thus its activation in a human bronchial cell line with endogenous p.Phe508del-CFTR expression and in bronchial cells from patients, to be more relevant to CF. This was achieved by inhibiting the protease MBTP1 which is responsible for the cleavage of ATF6. We show here that this inhibition leads to increased mRNA and p.Phe508del-CFTR expression and, consequently, to increased Cl-efflux. We also explain the mechanisms linked to these increases with the modulation of genes when MBTP1 is inhibited. Indeed, RT-qPCR assays show that genes such as HSPA1B, CEBPB, VIMP, PFND2, MAPK8, XBP1, INSIG1, and CALR are modulated. In conclusion, we show that the inhibition of MBTP1 has a beneficial effect in relevant models to CF and that this is due to the modulation of genes involved in the disease.
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Affiliation(s)
- Raphaël Santinelli
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Nathalie Benz
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Julie Guellec
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Fabien Quinquis
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Ervin Kocas
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Johan Thomas
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Tristan Montier
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Chandran Ka
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Emilie Luczka-Majérus
- Inserm UMR-S 1250, University of Reims Champagne-Ardenne (URCA), SFR Cap-Santé, F-51100 Reims, France; (E.L.-M.); (C.C.)
| | - Edouard Sage
- Université Paris-Saclay, INRAE, UVSQ, VIM, F-78350 Jouy-en-Josas, France;
| | - Claude Férec
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
| | - Christelle Coraux
- Inserm UMR-S 1250, University of Reims Champagne-Ardenne (URCA), SFR Cap-Santé, F-51100 Reims, France; (E.L.-M.); (C.C.)
| | - Pascal Trouvé
- Univ Brest, Inserm, EFS, UMR 1078, 22 Avenue Camille Desmoulins, F-29200 Brest, France; (R.S.); (N.B.); (J.G.); (F.Q.); (E.K.); (J.T.); (T.M.); (C.K.); (C.F.)
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Abedeera SM, Davila-Calderon J, Haddad C, Henry B, King J, Penumutchu S, Tolbert BS. The Repurposing of Cellular Proteins during Enterovirus A71 Infection. Viruses 2023; 16:75. [PMID: 38257775 PMCID: PMC10821071 DOI: 10.3390/v16010075] [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: 12/09/2023] [Revised: 12/27/2023] [Accepted: 12/29/2023] [Indexed: 01/24/2024] Open
Abstract
Viruses pose a great threat to people's lives. Enterovirus A71 (EV-A71) infects children and infants all over the world with no FDA-approved treatment to date. Understanding the basic mechanisms of viral processes aids in selecting more efficient drug targets and designing more effective antivirals to thwart this virus. The 5'-untranslated region (5'-UTR) of the viral RNA genome is composed of a cloverleaf structure and an internal ribosome entry site (IRES). Cellular proteins that bind to the cloverleaf structure regulate viral RNA synthesis, while those that bind to the IRES also known as IRES trans-acting factors (ITAFs) regulate viral translation. In this review, we survey the cellular proteins currently known to bind the 5'-UTR and influence viral gene expression with emphasis on comparing proteins' functions and localizations pre- and post-(EV-A71) infection. A comprehensive understanding of how the host cell's machinery is hijacked and reprogrammed by the virus to facilitate its replication is crucial for developing effective antivirals.
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Affiliation(s)
- Sudeshi M. Abedeera
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.A.); (B.H.); (S.P.)
| | - Jesse Davila-Calderon
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA; (J.D.-C.); (C.H.); (J.K.)
| | - Christina Haddad
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA; (J.D.-C.); (C.H.); (J.K.)
| | - Barrington Henry
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.A.); (B.H.); (S.P.)
| | - Josephine King
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA; (J.D.-C.); (C.H.); (J.K.)
| | - Srinivasa Penumutchu
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.A.); (B.H.); (S.P.)
| | - Blanton S. Tolbert
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; (S.M.A.); (B.H.); (S.P.)
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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5
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Hicks D, Giresh K, Wrischnik LA, Weiser DC. The PPP1R15 Family of eIF2-alpha Phosphatase Targeting Subunits (GADD34 and CReP). Int J Mol Sci 2023; 24:17321. [PMID: 38139150 PMCID: PMC10743859 DOI: 10.3390/ijms242417321] [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: 10/28/2023] [Revised: 12/01/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
The vertebrate PPP1R15 family consists of the proteins GADD34 (growth arrest and DNA damage-inducible protein 34, the product of the PPP1R15A gene) and CReP (constitutive repressor of eIF2α phosphorylation, the product of the PPP1R15B gene), both of which function as targeting/regulatory subunits for protein phosphatase 1 (PP1) by regulating subcellular localization, modulating substrate specificity and assembling complexes with target proteins. The primary cellular function of these proteins is to facilitate the dephosphorylation of eukaryotic initiation factor 2-alpha (eIF2α) by PP1 during cell stress. In this review, we will provide a comprehensive overview of the cellular function, biochemistry and pharmacology of GADD34 and CReP, starting with a brief introduction of eIF2α phosphorylation via the integrated protein response (ISR). We discuss the roles GADD34 and CReP play as feedback inhibitors of the unfolded protein response (UPR) and highlight the critical function they serve as inhibitors of the PERK-dependent branch, which is particularly important since it can mediate cell survival or cell death, depending on how long the stressful stimuli lasts, and GADD34 and CReP play key roles in fine-tuning this cellular decision. We briefly discuss the roles of GADD34 and CReP homologs in model systems and then focus on what we have learned about their function from knockout mice and human patients, followed by a brief review of several diseases in which GADD34 and CReP have been implicated, including cancer, diabetes and especially neurodegenerative disease. Because of the potential importance of GADD34 and CReP in aspects of human health and disease, we will discuss several pharmacological inhibitors of GADD34 and/or CReP that show promise as treatments and the controversies as to their mechanism of action. This review will finish with a discussion of the biochemical properties of GADD34 and CReP, their regulation and the additional interacting partners that may provide insight into the roles these proteins may play in other cellular pathways. We will conclude with a brief outline of critical areas for future study.
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Affiliation(s)
- Danielle Hicks
- Department of Science, Mathematics and Engineering, Modesto Junior College, Modesto, CA 95350, USA
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Krithika Giresh
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Lisa A. Wrischnik
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
| | - Douglas C. Weiser
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, USA
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Tomiyoshi G, Nakamura R, Shinmen N, Yoshida Y, Mine S, Machida T, Iwase K, Iwadate Y, Hiwasa T, Kuroda H. GADD34 activates p53 and may have utility as a marker of atherosclerosis. Front Med (Lausanne) 2023; 10:1128921. [PMID: 37228401 PMCID: PMC10203227 DOI: 10.3389/fmed.2023.1128921] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 04/11/2023] [Indexed: 05/27/2023] Open
Abstract
We previously identified growth arrest and DNA-damage-inducible gene 34 (GADD34) as a marker of ischemic stroke. In the present study, serum levels of anti-GADD34 antibodies were found to be significantly higher in patients with acute ischemic stroke or chronic kidney disease compared to healthy donors. We then examined the biological function of GADD34 by transfection into U2OS human osteosarcoma and U87 human glioblastoma cells. Knockdown of GADD34 by siRNA resulted in enhanced cell proliferation, which was reversed by co-knockdown of MDM2. Luciferase reporter assays revealed that the transactivation ability of p53 enhanced by genotoxic anticancer drugs such as camptothecin and etoposide was further potentiated by enforced expression of GADD34 but attenuated by co-transfection with p53 shRNA expression plasmids. Western blotting demonstrated increased p53 protein levels after treatment with camptothecin, which was also potentiated by GADD34 but suppressed by GADD34 siRNA, ATM siRNA, and ATM inhibitor wortmannin. GADD34 levels also increased in response to treatment with camptothecin or adriamycin, and this increase was attenuated by MDM2 siRNA. Immunoprecipitation with anti-GADD34 antibody followed by Western blotting with anti-MDM2 antibodies indicated ubiquitination of GADD34 is mediated by MDM2. Accordingly, GADD34 may function as a ubiquitination decoy to reduce p53 ubiquitination and increase p53 protein levels. Increased neuronal cell death due to activation of p53 by GADD34 may account for the elevated serum levels of anti-GADD34 antibodies observed in patients with acute ischemic stroke.
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Affiliation(s)
- Go Tomiyoshi
- Medical Project Division, Research Development Center, Fujikura Kasei Co., Saitama, Japan
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Rika Nakamura
- Medical Project Division, Research Development Center, Fujikura Kasei Co., Saitama, Japan
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Natsuko Shinmen
- Medical Project Division, Research Development Center, Fujikura Kasei Co., Saitama, Japan
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yoichi Yoshida
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Seiichiro Mine
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
- Department of Neurological Surgery, Chiba Prefectural Sawara Hospital, Chiba, Japan
- Department of Neurosurgery, Chiba Cerebral and Cardiovascular Center, Chiba, Japan
| | - Toshio Machida
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
- Department of Neurosurgery, Chiba Cerebral and Cardiovascular Center, Chiba, Japan
- Department of Neurosurgery, Eastern Chiba Medical Center, Chiba, Japan
| | - Katsuro Iwase
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Yasuo Iwadate
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Takaki Hiwasa
- Department of Biochemistry and Genetics, Graduate School of Medicine, Chiba University, Chiba, Japan
- Department of Neurological Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Hideyuki Kuroda
- Medical Project Division, Research Development Center, Fujikura Kasei Co., Saitama, Japan
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7
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Brownsword MJ, Locker N. A little less aggregation a little more replication: Viral manipulation of stress granules. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1741. [PMID: 35709333 PMCID: PMC10078398 DOI: 10.1002/wrna.1741] [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: 03/02/2022] [Revised: 04/29/2022] [Accepted: 05/05/2022] [Indexed: 01/31/2023]
Abstract
Recent exciting studies have uncovered how membrane-less organelles, also known as biocondensates, are providing cells with rapid response pathways, allowing them to re-organize their cellular contents and adapt to stressful conditions. Their assembly is driven by the phase separation of their RNAs and intrinsically disordered protein components into condensed foci. Among these, stress granules (SGs) are dynamic cytoplasmic biocondensates that form in response to many stresses, including activation of the integrated stress response or viral infections. SGs sit at the crossroads between antiviral signaling and translation because they concentrate signaling proteins and components of the innate immune response, in addition to translation machinery and stalled mRNAs. Consequently, they have been proposed to contribute to antiviral activities, and therefore are targeted by viral countermeasures. Equally, SGs components can be commandeered by viruses for their own efficient replication. Phase separation processes are an important component of the viral life cycle, for example, driving the assembly of replication factories or inclusion bodies. Therefore, in this review, we will outline the recent understanding of this complex interplay and tug of war between viruses, SGs, and their components. This article is categorized under: RNA in Disease and Development > RNA in Disease Translation > Regulation RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Matthew J. Brownsword
- Faculty of Health and Medical Sciences, School of Biosciences and MedicineUniversity of SurreyGuildfordSurreyUK
| | - Nicolas Locker
- Faculty of Health and Medical Sciences, School of Biosciences and MedicineUniversity of SurreyGuildfordSurreyUK
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8
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Bae S, Oh B, Tsai J, Park PSU, Greenblatt MB, Giannopoulou EG, Park-Min KH. The crosstalk between MYC and mTORC1 during osteoclastogenesis. Front Cell Dev Biol 2022; 10:920683. [PMID: 36060812 PMCID: PMC9437285 DOI: 10.3389/fcell.2022.920683] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 07/19/2022] [Indexed: 12/02/2022] Open
Abstract
Osteoclasts are bone-resorbing cells that undergo extensive changes in morphology throughout their differentiation. Altered osteoclast differentiation and activity lead to changes in pathological bone resorption. The mammalian target of rapamycin (mTOR) is a kinase, and aberrant mTOR complex 1 (mTORC1) signaling is associated with altered bone homeostasis. The activation of mTORC1 is biphasically regulated during osteoclastogenesis; however, the mechanism behind mTORC1-mediated regulation of osteoclastogenesis and bone resorption is incompletely understood. Here, we found that MYC coordinates the dynamic regulation of mTORC1 activation during osteoclastogenesis. MYC-deficiency blocked the early activation of mTORC1 and also reversed the decreased activity of mTORC1 at the late stage of osteoclastogenesis. The suppression of mTORC1 activity by rapamycin in mature osteoclasts enhances bone resorption activity despite the indispensable role of high mTORC1 activation in osteoclast formation in both mouse and human cells. Mechanistically, MYC induces Growth arrest and DNA damage-inducible protein (GADD34) expression and suppresses mTORC1 activity at the late phase of osteoclastogenesis. Taken together, our findings identify a MYC-GADD34 axis as an upstream regulator of dynamic mTORC1 activation in osteoclastogenesis and highlight the interplay between MYC and mTORC1 pathways in determining osteoclast activity.
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Affiliation(s)
- Seyeon Bae
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
- Department of Medicine, Weill Cornell Medical College, New York, NY, United States
| | - Brian Oh
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
| | - Jefferson Tsai
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
| | - Peter Sang Uk Park
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
| | | | - Eugenia G. Giannopoulou
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
- Biological Sciences Department, New York City College of Technology, City University of New York, Brooklyn, NY, United States
| | - Kyung-Hyun Park-Min
- Arthritis and Tissue Degeneration Program, David Z. Rosensweig Genomics Research Center, Hospital for Special Surgery, New York, NY, United States
- Department of Medicine, Weill Cornell Medical College, New York, NY, United States
- BCMB Allied Program, Weill Cornell Graduate School of Medical Sciences, New York, NY, United States
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9
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Klein P, Kallenberger SM, Roth H, Roth K, Ly-Hartig TBN, Magg V, Aleš J, Talemi SR, Qiang Y, Wolf S, Oleksiuk O, Kurilov R, Di Ventura B, Bartenschlager R, Eils R, Rohr K, Hamprecht FA, Höfer T, Fackler OT, Stoecklin G, Ruggieri A. Temporal control of the integrated stress response by a stochastic molecular switch. SCIENCE ADVANCES 2022; 8:eabk2022. [PMID: 35319985 PMCID: PMC8942376 DOI: 10.1126/sciadv.abk2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Stress granules (SGs) are formed in the cytosol as an acute response to environmental cues and activation of the integrated stress response (ISR), a central signaling pathway controlling protein synthesis. Using chronic virus infection as stress model, we previously uncovered a unique temporal control of the ISR resulting in recurrent phases of SG assembly and disassembly. Here, we elucidate the molecular network generating this fluctuating stress response by integrating quantitative experiments with mathematical modeling and find that the ISR operates as a stochastic switch. Key elements controlling this switch are the cooperative activation of the stress-sensing kinase PKR, the ultrasensitive response of SG formation to the phosphorylation of the translation initiation factor eIF2α, and negative feedback via GADD34, a stress-induced subunit of protein phosphatase 1. We identify GADD34 messenger RNA levels as the molecular memory of the ISR that plays a central role in cell adaptation to acute and chronic stress.
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Affiliation(s)
- Philipp Klein
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Diseases Research, Heidelberg University, Heidelberg, Germany
| | - Stefan M. Kallenberger
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Digital Health Center, Berlin Institute of Health (BIH) and Charité, Berlin, Germany
- Medical Oncology, National Center for Tumor Diseases, Heidelberg University, Heidelberg, Germany
| | - Hanna Roth
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Diseases Research, Heidelberg University, Heidelberg, Germany
| | - Karsten Roth
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Diseases Research, Heidelberg University, Heidelberg, Germany
| | - Thi Bach Nga Ly-Hartig
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Vera Magg
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Diseases Research, Heidelberg University, Heidelberg, Germany
| | - Janez Aleš
- HCI/IWR, Heidelberg University, Heidelberg, Germany
| | - Soheil Rastgou Talemi
- Division of Theoretical Systems Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Yu Qiang
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Heidelberg, Germany
| | - Steffen Wolf
- HCI/IWR, Heidelberg University, Heidelberg, Germany
| | - Olga Oleksiuk
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Diseases Research, Heidelberg University, Heidelberg, Germany
| | - Roma Kurilov
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Barbara Di Ventura
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Diseases Research, Heidelberg University, Heidelberg, Germany
- Division Virus-Associated Carcinogenesis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Roland Eils
- Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Digital Health Center, Berlin Institute of Health (BIH) and Charité, Berlin, Germany
| | - Karl Rohr
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Heidelberg, Germany
| | | | - Thomas Höfer
- Division of Theoretical Systems Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Oliver T. Fackler
- Department of Infectious Diseases, Integrative Virology, Center for Integrative Infectious Diseases Research, Heidelberg University, Heidelberg, Germany
| | - Georg Stoecklin
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Alessia Ruggieri
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Diseases Research, Heidelberg University, Heidelberg, Germany
- Corresponding author.
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10
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Abstract
Enterovirus 71 (EV71) is the major pathogen of hand, foot, and mouth disease. In severe cases, it can cause life-threatening neurological complications, such as aseptic meningitis and polio-like paralysis. There are no specific antiviral treatments for EV71 infections. In a previous study, the host protein growth arrest and DNA damage-inducible protein 34 (GADD34) expression was upregulated during EV71 infection determined by ribosome profiling and RNA-sequencing. Here, we investigated the interactions of host protein GADD34 and EV71 during infections. Rhabdomyosarcoma (RD) cells were infected with EV71 resulting in a significant increase in expression of GADD34 mRNA and protein. Through screening of EV71 protein we determined that the non-structural precursor protein 3CD is responsible for upregulating GADD34. EV71 3CD increased the RNA and protein levels of GADD34, while the 3CD mutant Y441S could not. 3CD upregulated GADD34 translation via the upstream open reading frame (uORF) of GADD34 5'untranslated regions (UTR). EV71 replication was attenuated by the knockdown of GADD34. The function of GADD34 to dephosphorylate eIF2α was unrelated to the upregulation of EV71 replication, but the PEST 1, 2, and 3 regions of GADD34 were required. GADD34 promoted the EV71 internal ribosome entry site (IRES) activity through the PEST repeats and affected several other viruses. Finally, GADD34 amino acids 563 to 565 interacted with 3CD, assisting GADD34 to target the EV71 IRES. Our research reveals a new mechanism by which GADD34 promotes viral IRES and how the EV71 non-structural precursor protein 3CD regulates host protein expression to support viral replication. IMPORTANCE Identification of host factors involved in viral replication is an important approach in discovering viral pathogenic mechanisms and identifying potential therapeutic targets. Previously, we screened host proteins that were upregulated by EV71 infection. Here, we report the interaction between the upregulated host protein GADD34 and EV71. EV71 non-structural precursor protein 3CD activates the RNA and protein expression of GADD34. Our study reveals that 3CD regulates the uORF of the 5′-UTR to increase GADD34 translation, providing a new explanation for how viral proteins regulate host protein expression. GADD34 is important for EV71 replication, and the key functional domains of GADD34 that promote EV71 are PEST 1, 2, and 3 regions. We report that GADD34 promotes viral IRES for the first time and this process is independent of its eIF2α phosphatase activity.
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11
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Monkley S, Overed-Sayer C, Parfrey H, Rassl D, Crowther D, Escudero-Ibarz L, Davis N, Carruthers A, Berks R, Coetzee M, Kolosionek E, Karlsson M, Griffin LR, Clausen M, Belfield G, Hogaboam CM, Murray LA. Sensitization of the UPR by loss of PPP1R15A promotes fibrosis and senescence in IPF. Sci Rep 2021; 11:21584. [PMID: 34732748 PMCID: PMC8566588 DOI: 10.1038/s41598-021-00769-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 10/11/2021] [Indexed: 02/07/2023] Open
Abstract
The unfolded protein response (UPR) is a direct consequence of cellular endoplasmic reticulum (ER) stress and a key disease driving mechanism in IPF. The resolution of the UPR is directed by PPP1R15A (GADD34) and leads to the restoration of normal ribosomal activity. While the role of PPP1R15A has been explored in lung epithelial cells, the role of this UPR resolving factor has yet to be explored in lung mesenchymal cells. The objective of the current study was to determine the expression and role of PPP1R15A in IPF fibroblasts and in a bleomycin-induced lung fibrosis model. A survey of IPF lung tissue revealed that PPP1R15A expression was markedly reduced. Targeting PPP1R15A in primary fibroblasts modulated TGF-β-induced fibroblast to myofibroblast differentiation and exacerbated pulmonary fibrosis in bleomycin-challenged mice. Interestingly, the loss of PPP1R15A appeared to promote lung fibroblast senescence. Taken together, our findings demonstrate the major role of PPP1R15A in the regulation of lung mesenchymal cells, and regulation of PPP1R15A may represent a novel therapeutic strategy in IPF.
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Affiliation(s)
- Susan Monkley
- Translational Science and Experimental Medicine, Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Catherine Overed-Sayer
- Bioscience COPD/IPF, Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Helen Parfrey
- Cambridge Interstitial Lung Disease Service, Royal Papworth Hospital, Cambridge, UK
| | | | - Damian Crowther
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | | | - Nicola Davis
- Bioscience COPD/IPF, Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Alan Carruthers
- Bioscience COPD/IPF, Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Richard Berks
- Biological Services Group, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, UK
| | | | - Ewa Kolosionek
- Bioscience COPD/IPF, Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Maria Karlsson
- Bioscience COPD/IPF, Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Leia R Griffin
- Bioscience COPD/IPF, Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Maryam Clausen
- Translational Genomics, Discovery Biology, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Graham Belfield
- Translational Genomics, Discovery Biology, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Cory M Hogaboam
- Cedars-Sinai Department of Medicine, Los Angeles, CA, 90048, USA
| | - Lynne A Murray
- Bioscience COPD/IPF, Research and Early Development, Respiratory and Immunology, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK.
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12
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Yousuf MS, Shiers SI, Sahn JJ, Price TJ. Pharmacological Manipulation of Translation as a Therapeutic Target for Chronic Pain. Pharmacol Rev 2021; 73:59-88. [PMID: 33203717 PMCID: PMC7736833 DOI: 10.1124/pharmrev.120.000030] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Dysfunction in regulation of mRNA translation is an increasingly recognized characteristic of many diseases and disorders, including cancer, diabetes, autoimmunity, neurodegeneration, and chronic pain. Approximately 50 million adults in the United States experience chronic pain. This economic burden is greater than annual costs associated with heart disease, cancer, and diabetes combined. Treatment options for chronic pain are inadequately efficacious and riddled with adverse side effects. There is thus an urgent unmet need for novel approaches to treating chronic pain. Sensitization of neurons along the nociceptive pathway causes chronic pain states driving symptoms that include spontaneous pain and mechanical and thermal hypersensitivity. More than a decade of preclinical research demonstrates that translational mechanisms regulate the changes in gene expression that are required for ongoing sensitization of nociceptive sensory neurons. This review will describe how key translation regulation signaling pathways, including the integrated stress response, mammalian target of rapamycin, AMP-activated protein kinase (AMPK), and mitogen-activated protein kinase-interacting kinases, impact the translation of different subsets of mRNAs. We then place these mechanisms of translation regulation in the context of chronic pain states, evaluate currently available therapies, and examine the potential for developing novel drugs. Considering the large body of evidence now published in this area, we propose that pharmacologically manipulating specific aspects of the translational machinery may reverse key neuronal phenotypic changes causing different chronic pain conditions. Therapeutics targeting these pathways could eventually be first-line drugs used to treat chronic pain disorders. SIGNIFICANCE STATEMENT: Translational mechanisms regulating protein synthesis underlie phenotypic changes in the sensory nervous system that drive chronic pain states. This review highlights regulatory mechanisms that control translation initiation and how to exploit them in treating persistent pain conditions. We explore the role of mammalian/mechanistic target of rapamycin and mitogen-activated protein kinase-interacting kinase inhibitors and AMPK activators in alleviating pain hypersensitivity. Modulation of eukaryotic initiation factor 2α phosphorylation is also discussed as a potential therapy. Targeting specific translation regulation mechanisms may reverse changes in neuronal hyperexcitability associated with painful conditions.
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Affiliation(s)
- Muhammad Saad Yousuf
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas (M.S.Y., S.I.S., T.J.P.) and 4E Therapeutics Inc, Austin, Texas (J.J.S.)
| | - Stephanie I Shiers
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas (M.S.Y., S.I.S., T.J.P.) and 4E Therapeutics Inc, Austin, Texas (J.J.S.)
| | - James J Sahn
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas (M.S.Y., S.I.S., T.J.P.) and 4E Therapeutics Inc, Austin, Texas (J.J.S.)
| | - Theodore J Price
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas (M.S.Y., S.I.S., T.J.P.) and 4E Therapeutics Inc, Austin, Texas (J.J.S.)
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13
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Post-Transcriptional Regulation of Alpha One Antitrypsin by a Proteasome Inhibitor. Int J Mol Sci 2020; 21:ijms21124318. [PMID: 32560429 PMCID: PMC7352753 DOI: 10.3390/ijms21124318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/09/2020] [Accepted: 06/16/2020] [Indexed: 12/25/2022] Open
Abstract
Alpha one antitrypsin (α1AT), a serine proteinase inhibitor primarily produced by the liver, protects pulmonary tissue from neutrophil elastase digestion. Mutations of the SERPINA1 gene results in a misfolded α1AT protein which aggregates inside hepatocytes causing cellular damage. Therefore, inhibition of mutant α1AT production is one practical strategy to alleviate liver damage. Here we show that proteasome inhibitors can selectively downregulate α1AT expression in human hepatocytes by suppressing the translation of α1AT. Translational suppression of α1AT is mediated by phosphorylation of eukaryotic translation initiation factor 2α and increased association of RNA binding proteins, especially stress granule protein Ras GAP SH3 binding protein (G3BP1), with α1AT mRNA. Treatment of human-induced pluripotent stem cell-derived hepatocytes with a proteasome inhibitor also results in translational inhibition of mutant α1AT in a similar manner. Together we revealed a previously undocumented role of proteasome inhibitors in the regulation of α1AT translation.
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14
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Ishaq M, Marshall H, Natarajan V. GADD34 attenuates HIV-1 replication by viral 5'-UTR TAR RNA-mediated translational inhibition. Virology 2020; 540:119-131. [PMID: 31778897 PMCID: PMC6957764 DOI: 10.1016/j.virol.2019.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 11/07/2019] [Accepted: 11/08/2019] [Indexed: 10/25/2022]
Abstract
Role of GADD34, a protein that is induced following cellular stress, in HIV-1 replication was investigated. GADD34 was induced during the late phase of HIV-1 infection. siRNA-knockdown of GADD34 stimulated whereas overexpression of GADD34 inhibited HIV-1 replication. GADD34 N-terminal ER-binding-helix amino acid region 1-192 alone was found to be sufficient for the inhibition of HIV-1 replication whereas protein-phosphatase -1-binding domain and eIF-2α-phosphatase activity of GADD34 were not crucial for anti-HIV-1 activity. GADD34 did not alter the HIV-1 RNA levels but reduced the viral protein expression suggesting that GADD34 interferes in HIV protein synthesis. Studies on the effect of HIV-1-5'-UTR and its mutants on a human promoter-driven luciferase expression indicated that GADD34-inhibition was mediated by 5'-UTR/TAR RNA, probably by modulating TAR RNA structure. In summary, our data support a novel function of GADD34 as a putative anti-HIV-1 restriction factor.
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Affiliation(s)
- Mohammad Ishaq
- Laboratory of Molecular Cell Biology, Leidos Biomedical Research Inc, Frederick National Laboratory for Cancer Research, P.O. Box B, Frederick, MD, 21702, USA.
| | - Heather Marshall
- Laboratory of Molecular Cell Biology, Leidos Biomedical Research Inc, Frederick National Laboratory for Cancer Research, P.O. Box B, Frederick, MD, 21702, USA
| | - Ven Natarajan
- Laboratory of Molecular Cell Biology, Leidos Biomedical Research Inc, Frederick National Laboratory for Cancer Research, P.O. Box B, Frederick, MD, 21702, USA.
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15
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Brautigan DL, Shenolikar S. Protein Serine/Threonine Phosphatases: Keys to Unlocking Regulators and Substrates. Annu Rev Biochem 2019; 87:921-964. [PMID: 29925267 DOI: 10.1146/annurev-biochem-062917-012332] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Protein serine/threonine phosphatases (PPPs) are ancient enzymes, with distinct types conserved across eukaryotic evolution. PPPs are segregated into types primarily on the basis of the unique interactions of PPP catalytic subunits with regulatory proteins. The resulting holoenzymes dock substrates distal to the active site to enhance specificity. This review focuses on the subunit and substrate interactions for PPP that depend on short linear motifs. Insights about these motifs from structures of holoenzymes open new opportunities for computational biology approaches to elucidate PPP networks. There is an expanding knowledge base of posttranslational modifications of PPP catalytic and regulatory subunits, as well as of their substrates, including phosphorylation, acetylation, and ubiquitination. Cross talk between these posttranslational modifications creates PPP-based signaling. Knowledge of PPP complexes, signaling clusters, as well as how PPPs communicate with each other in response to cellular signals should unlock the doors to PPP networks and signaling "clouds" that orchestrate and coordinate different aspects of cell physiology.
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Affiliation(s)
- David L Brautigan
- Center for Cell Signaling and Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, USA;
| | - Shirish Shenolikar
- Signature Research Programs in Cardiovascular and Metabolic Disorders and Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore 169857
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16
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Nakashima H, Nguyen T, Kasai K, Passaro C, Ito H, Goins WF, Shaikh I, Erdelyi R, Nishihara R, Nakano I, Reardon DA, Anderson AC, Kuchroo V, Chiocca EA. Toxicity and Efficacy of a Novel GADD34-expressing Oncolytic HSV-1 for the Treatment of Experimental Glioblastoma. Clin Cancer Res 2018; 24:2574-2584. [PMID: 29511029 PMCID: PMC6800093 DOI: 10.1158/1078-0432.ccr-17-2954] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 01/18/2018] [Accepted: 03/01/2018] [Indexed: 02/07/2023]
Abstract
Purpose: Glioblastoma (GBM) is the most common primary central nervous system cancer in adults. Oncolytic HSV-1 (oHSV) is the first FDA-approved gene therapy approach for the treatment of malignant melanoma. For GBM, oHSVs need to be engineered to replicate within and be toxic to the glial tumor but not to normal brain parenchymal cells. We have thus engineered a novel oHSV to achieve these objectives.Experimental Design: NG34 is an attenuated HSV-1 with deletions in the genes encoding viral ICP6 and ICP34.5. These mutations suppress virus replication in nondividing brain neurons. NG34 expresses the human GADD34 gene under transcriptional control of a cellular Nestin gene promoter/enhancer element, whose expression occurs selectively in GBM. In vitro cytotoxicity assay and survival studies with mouse models were performed to evaluate therapeutic potency of NG34 against glioblastoma. In vivo neurotoxicity evaluation of NG34 was tested by intracerebral inoculation.Results: NG34 replicates in GBM cells in vitro with similar kinetics as those exhibited by an oHSV that is currently in clinical trials (rQNestin34.5). Dose-response cytotoxicity of NG34 in human GBM panels was equivalent to or improved compared with rQNestin34.5. The in vivo efficacy of NG34 against two human orthotopic GBM models in athymic mice was similar to that of rQNestin34.5, whereas intracerebral injection of NG34 in the brains of immunocompetent and athymic mice showed significantly better tolerability. NG34 was also effective in a syngeneic mouse glioblastoma model.Conclusions: A novel oHSV encoding GADD34 is efficacious and relatively nontoxic in mouse models of GBM. Clin Cancer Res; 24(11); 2574-84. ©2018 AACR.
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Affiliation(s)
- Hiroshi Nakashima
- Harvey W. Cushing Neuro-oncology Laboratories (HCNL), Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts.
| | - Tran Nguyen
- Harvey W. Cushing Neuro-oncology Laboratories (HCNL), Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts
| | - Kazue Kasai
- Harvey W. Cushing Neuro-oncology Laboratories (HCNL), Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts
| | - Carmela Passaro
- Harvey W. Cushing Neuro-oncology Laboratories (HCNL), Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts
| | - Hirotaka Ito
- Harvey W. Cushing Neuro-oncology Laboratories (HCNL), Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts
| | - William F Goins
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Imran Shaikh
- Department of Neurological Surgery, The Ohio State University, Columbus, Ohio
| | - Ronald Erdelyi
- Department of Neurological Surgery, The Ohio State University, Columbus, Ohio
| | - Reiko Nishihara
- Department of Pathology, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts
| | - Ichiro Nakano
- Department of Neurological Surgery, The Ohio State University, Columbus, Ohio
| | - David A Reardon
- Center for Neuro-Oncology, Dana-Farber Cancer Institute, and Brigham and Women's Hospital, Boston, Massachusetts
| | - Ana C Anderson
- Evergrande Center for Immunologic Diseases and Ann Romney Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts
| | - Vijay Kuchroo
- Evergrande Center for Immunologic Diseases and Ann Romney Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts
| | - E Antonio Chiocca
- Harvey W. Cushing Neuro-oncology Laboratories (HCNL), Department of Neurosurgery, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts.
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17
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Crespillo-Casado A, Claes Z, Choy MS, Peti W, Bollen M, Ron D. A Sephin1-insensitive tripartite holophosphatase dephosphorylates translation initiation factor 2α. J Biol Chem 2018; 293:7766-7776. [PMID: 29618508 PMCID: PMC5961032 DOI: 10.1074/jbc.ra118.002325] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/28/2018] [Indexed: 11/10/2022] Open
Abstract
The integrated stress response (ISR) is regulated by kinases that phosphorylate the α subunit of translation initiation factor 2 and phosphatases that dephosphorylate it. Genetic and biochemical observations indicate that the eIF2αP-directed holophosphatase, a therapeutic target in diseases of protein misfolding, is comprised of a regulatory subunit, PPP1R15, and a catalytic subunit, protein phosphatase 1 (PP1). In mammals, there are two isoforms of the regulatory subunit, PPP1R15A and PPP1R15B, with overlapping roles in the essential function of eIF2αP dephosphorylation. However, conflicting reports have appeared regarding the requirement for an additional co-factor, G-actin, in enabling substrate-specific dephosphorylation by PPP1R15-containing PP1 holoenzymes. An additional concern relates to the sensitivity of the holoenzyme to the [(o-chlorobenzylidene)amino]guanidines Sephin1 or guanabenz, putative small-molecule proteostasis modulators. It has been suggested that the source and method of purification of the PP1 catalytic subunit and the presence or absence of an N-terminal repeat–containing region in the PPP1R15A regulatory subunit might influence the requirement for G-actin and sensitivity of the holoenzyme to inhibitors. We found that eIF2αP dephosphorylation by PP1 was moderately stimulated by repeat-containing PPP1R15A in an unphysiological low ionic strength buffer, whereas stimulation imparted by the co-presence of PPP1R15A and G-actin was observed under a broad range of conditions, low and physiological ionic strength, regardless of whether the PPP1R15A regulatory subunit had or lacked the N-terminal repeat–containing region and whether it was paired with native PP1 purified from rabbit muscle or recombinant PP1 purified from bacteria. Furthermore, none of the PPP1R15A-containing holophosphatases tested were inhibited by Sephin1 or guanabenz.
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Affiliation(s)
- Ana Crespillo-Casado
- From the Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom,
| | - Zander Claes
- the Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium, and
| | - Meng S Choy
- the Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721-0041
| | - Wolfgang Peti
- the Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721-0041
| | - Mathieu Bollen
- the Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium, and
| | - David Ron
- From the Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom,
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18
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Melas PA, Qvist JS, Deidda M, Upreti C, Wei YB, Sanna F, Fratta W, Scherma M, Fadda P, Kandel DB, Kandel ER. Cannabinoid Modulation of Eukaryotic Initiation Factors (eIF2α and eIF2B1) and Behavioral Cross-Sensitization to Cocaine in Adolescent Rats. Cell Rep 2018. [DOI: 10.1016/j.celrep.2018.02.065] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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19
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Goh CW, Lee IC, Sundaram JR, George SE, Yusoff P, Brush MH, Sze NSK, Shenolikar S. Chronic oxidative stress promotes GADD34-mediated phosphorylation of the TAR DNA-binding protein TDP-43, a modification linked to neurodegeneration. J Biol Chem 2017; 293:163-176. [PMID: 29109149 DOI: 10.1074/jbc.m117.814111] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 11/01/2017] [Indexed: 12/28/2022] Open
Abstract
Oxidative and endoplasmic reticulum (ER) stresses are hallmarks of the pathophysiology of ALS and other neurodegenerative diseases. In these stresses, different kinases phosphorylate eukaryotic initiation factor eIF2α, enabling the translation of stress response genes; among these is GADD34, the protein product of which recruits the α-isoform of protein phosphatase 1 catalytic subunit (PP1α) and eIF2α to assemble a phosphatase complex catalyzing eIF2α dephosphorylation and resumption of protein synthesis. Aberrations in this pathway underlie the aforementioned disorders. Previous observations indicating that GADD34 is induced by arsenite, a thiol-directed oxidative stressor, in the absence of eIF2α phosphorylation suggest other roles for GADD34. Here, we report that arsenite-induced oxidative stress differs from thapsigargin- or tunicamycin-induced ER stress in promoting GADD34 transcription and the preferential translation of its mRNA in the absence of eIF2α phosphorylation. Arsenite also stabilized GADD34 protein, slowing its degradation. In response to oxidative stress, but not ER stress, GADD34 recruited TDP-43, and enhanced cytoplasmic distribution and cysteine modifications of TDP-43 promoted its binding to GADD34. Arsenite also recruited a TDP-43 kinase, casein kinase-1ϵ (CK1ϵ), to GADD34. Concomitant with TDP-43 aggregation and proteolysis after prolonged arsenite exposure, GADD34-bound CK1ϵ catalyzed TDP-43 phosphorylations at serines 409/410, which were diminished or absent in GADD34-/- cells. Our findings highlight that the phosphatase regulator, GADD34, also functions as a kinase scaffold in response to chronic oxidative stress and recruits CK1ϵ and oxidized TDP-43 to facilitate its phosphorylation, as seen in TDP-43 proteinopathies.
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Affiliation(s)
- Catherine Wenhui Goh
- Signature Research Programs in Neuroscience and Behavioural Disorders, Singapore 169857, Singapore
| | - Irene Chengjie Lee
- Signature Research Programs in Neuroscience and Behavioural Disorders, Singapore 169857, Singapore; Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Jeyapriya Rajameenakshi Sundaram
- Signature Research Programs in Neuroscience and Behavioural Disorders, Singapore 169857, Singapore; Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Simi Elizabeth George
- Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Permeen Yusoff
- Signature Research Programs in Neuroscience and Behavioural Disorders, Singapore 169857, Singapore; Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Matthew Hayden Brush
- Ontology Development group, Oregon Health and Science University, Portland, Oregon 97239
| | - Newman Siu Kwan Sze
- School of Biological Sciences, Nanyang Technological University, Singapore 639798, Singapore
| | - Shirish Shenolikar
- Signature Research Programs in Neuroscience and Behavioural Disorders, Singapore 169857, Singapore; Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore 169857, Singapore; Department of Psychiatry and Behavioral Sciences and Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina 27710.
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20
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VerPlank JJS, Lokireddy S, Feltri ML, Goldberg AL, Wrabetz L. Impairment of protein degradation and proteasome function in hereditary neuropathies. Glia 2017; 66:379-395. [PMID: 29076578 DOI: 10.1002/glia.23251] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 09/10/2017] [Accepted: 10/09/2017] [Indexed: 01/02/2023]
Abstract
In several neurodegenerative diseases in which misfolded proteins accumulate there is impairment of the ubiquitin proteasome system (UPS). We tested if a similar disruption of proteostasis occurs in hereditary peripheral neuropathies. In sciatic nerves from mouse models of two human neuropathies, Myelin Protein Zero mutation (S63del) and increased copy number (P0 overexpression), polyubiquitinated proteins accumulated, and the overall rates of protein degradation were decreased. 26S proteasomes affinity-purified from sciatic nerves of S63del mice were defective in degradation of peptides and a ubiquitinated protein, unlike proteasomes from P0 overexpression, which appeared normal. Nevertheless, cellular levels of 26S proteasomes were increased in both, through the proteolytic-activation of the transcription factor Nrf1, as occurs in response to proteasome inhibitors. In S63del, increased amounts of the deubiquitinating enzymes USP14, UCH37, and USP5 were associated with proteasomes, the first time this has been reported in a human disease model. Inhibitors of USP14 increased the rate of protein degradation in S63del sciatic nerves and unexpectedly increased the phosphorylation of eIF2α by Perk. Thus, proteasome content, composition and activity are altered in these diseases and USP14 inhibitors have therapeutic potential in S63del neuropathy.
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Affiliation(s)
- Jordan J S VerPlank
- Hunter James Kelly Research Institute and Departments of, Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York.,Harvard Medical School, Boston, Massachusetts
| | | | - M Laura Feltri
- Hunter James Kelly Research Institute and Departments of, Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York
| | | | - Lawrence Wrabetz
- Hunter James Kelly Research Institute and Departments of, Biochemistry and Neurology, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York
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21
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Oxidative stress promotes SIRT1 recruitment to the GADD34/PP1α complex to activate its deacetylase function. Cell Death Differ 2017; 25:255-267. [PMID: 28984870 DOI: 10.1038/cdd.2017.152] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 08/01/2017] [Accepted: 08/15/2017] [Indexed: 12/20/2022] Open
Abstract
Phosphorylation of the eukaryotic translation initiation factor, eIF2α, by stress-activated protein kinases and dephosphorylation by the growth arrest and DNA damage-inducible protein (GADD34)-containing phosphatase is a central node in the integrated stress response. Mass spectrometry demonstrated GADD34 acetylation at multiple lysines. Substituting K315 and K322 with alanines or glutamines did not impair GADD34's ability to recruit protein phosphatase 1α (PP1α) or eIF2α, suggesting that GADD34 acetylation did not modulate eIF2α phosphatase activity. Arsenite (Ars)-induced oxidative stress increased cellular GADD34 levels and enhanced Sirtuin 1 (SIRT1) recruitment to assemble a cytoplasmic complex containing GADD34, PP1α, eIF2α and SIRT1. Induction of GADD34 in WT MEFs paralleled the dephosphorylation of eIF2α (phosphoserine-51) and SIRT1 (phosphoserine-47). By comparison, eIF2α and SIRT1 were persistently phosphorylated in Ars-treated GADD34-/- MEFs. Expressing WT GADD34, but not a mutant unable to bind PP1α in GADD34-/- MEFs restored both eIF2α and SIRT1 dephosphorylation. SIRT1 dephosphorylation increased its deacetylase activity, measured in vitro and in cells. Loss of function of GADD34 or SIRT1 enhanced cellular p-eIF2α levels and attenuated cell death following Ars exposure. These results highlighted a novel role for the GADD34/PP1α complex in coordinating the dephosphorylation and reactivation of eIF2α and SIRT1 to determine cell fate following oxidative stress.
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22
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Translating protein phosphatase research into treatments for neurodegenerative diseases. Biochem Soc Trans 2017; 45:101-112. [PMID: 28202663 DOI: 10.1042/bst20160157] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 11/21/2016] [Accepted: 11/23/2016] [Indexed: 12/11/2022]
Abstract
Many of the major neurodegenerative disorders are characterized by the accumulation of intracellular protein aggregates in neurons and other cells in brain, suggesting that errors in protein quality control mechanisms associated with the aging process play a critical role in the onset and progression of disease. The increased understanding of the unfolded protein response (UPR) signaling network and, more specifically, the structure and function of eIF2α phosphatases has enabled the development or discovery of small molecule inhibitors that show great promise in restoring protein homeostasis and ameliorating neuronal damage and death. While this review focuses attention on one or more eIF2α phosphatases, the wide range of UPR proteins that are currently being explored as potential drug targets bodes well for the successful future development of therapies to preserve neuronal function and treat neurodegenerative disease.
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23
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Crespillo-Casado A, Chambers JE, Fischer PM, Marciniak SJ, Ron D. PPP1R15A-mediated dephosphorylation of eIF2α is unaffected by Sephin1 or Guanabenz. eLife 2017; 6. [PMID: 28447936 PMCID: PMC5429092 DOI: 10.7554/elife.26109] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/21/2017] [Indexed: 12/18/2022] Open
Abstract
Dephosphorylation of translation initiation factor 2 (eIF2α) terminates signalling in the mammalian integrated stress response (ISR) and has emerged as a promising target for modifying the course of protein misfolding diseases. The [(o-chlorobenzylidene)amino]guanidines (Guanabenz and Sephin1) have been proposed to exert protective effects against misfolding by interfering with eIF2α-P dephosphorylation through selective disruption of a PP1-PPP1R15A holophosphatase complex. Surprisingly, they proved inert in vitro affecting neither stability of the PP1-PPP1R15A complex nor substrate-specific dephosphorylation. Furthermore, eIF2α-P dephosphorylation, assessed by a kinase shut-off experiment, progressed normally in Sephin1-treated cells. Consistent with its role in defending proteostasis, Sephin1 attenuated the IRE1 branch of the endoplasmic reticulum unfolded protein response. However, repression was noted in both wildtype and Ppp1r15a deleted cells and in cells rendered ISR-deficient by CRISPR editing of the Eif2s1 locus to encode a non-phosphorylatable eIF2α (eIF2αS51A). These findings challenge the view that [(o-chlorobenzylidene)amino]guanidines restore proteostasis by interfering with eIF2α-P dephosphorylation.
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Affiliation(s)
- Ana Crespillo-Casado
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Joseph E Chambers
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Peter M Fischer
- Division of Biomolecular Science and Medicinal Chemistry, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom.,Centre for Biomolecular Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Stefan J Marciniak
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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24
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Dalet A, Argüello RJ, Combes A, Spinelli L, Jaeger S, Fallet M, Vu Manh TP, Mendes A, Perego J, Reverendo M, Camosseto V, Dalod M, Weil T, Santos MA, Gatti E, Pierre P. Protein synthesis inhibition and GADD34 control IFN-β heterogeneous expression in response to dsRNA. EMBO J 2017; 36:761-782. [PMID: 28100675 DOI: 10.15252/embj.201695000] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 12/20/2016] [Accepted: 12/22/2016] [Indexed: 02/01/2023] Open
Abstract
In innate immune responses, induction of type-I interferons (IFNs) prevents virus spreading while viral replication is delayed by protein synthesis inhibition. We asked how cells perform these apparently contradictory activities. Using single fibroblast monitoring by flow cytometry and mathematical modeling, we demonstrate that type-I IFN production is linked to cell's ability to enter dsRNA-activated PKR-dependent translational arrest and then overcome this inhibition by decreasing eIF2α phosphorylation through phosphatase 1c cofactor GADD34 (Ppp1r15a) expression. GADD34 expression, shown here to be dependent on the IRF3 transcription factor, is responsible for a biochemical cycle permitting pulse of IFN synthesis to occur in cells undergoing protein synthesis inhibition. Translation arrest is further demonstrated to be key for anti-viral response by acting synergistically with MAVS activation to amplify TBK1 signaling and IFN-β mRNA transcription, while GADD34-dependent protein synthesis recovery contributes to the heterogeneous expression of IFN observed in dsRNA-activated cells.
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Affiliation(s)
- Alexandre Dalet
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France
| | | | - Alexis Combes
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France
| | - Lionel Spinelli
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France
| | | | - Mathieu Fallet
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France
| | | | - Andreia Mendes
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France
| | - Jessica Perego
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France
| | | | - Voahirana Camosseto
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France.,International associated laboratory (LIA) CNRS "Mistra", Marseille, France
| | - Marc Dalod
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France
| | - Tobias Weil
- Institute for Research in Biomedicine - iBiMED and Aveiro Health Sciences Program, University of Aveiro, Aveiro, Portugal
| | - Manuel A Santos
- International associated laboratory (LIA) CNRS "Mistra", Marseille, France.,Institute for Research in Biomedicine - iBiMED and Aveiro Health Sciences Program, University of Aveiro, Aveiro, Portugal
| | - Evelina Gatti
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France .,International associated laboratory (LIA) CNRS "Mistra", Marseille, France.,Institute for Research in Biomedicine - iBiMED and Aveiro Health Sciences Program, University of Aveiro, Aveiro, Portugal
| | - Philippe Pierre
- CNRS, INSERM, CIML, Aix Marseille University, Marseille, France .,International associated laboratory (LIA) CNRS "Mistra", Marseille, France.,Institute for Research in Biomedicine - iBiMED and Aveiro Health Sciences Program, University of Aveiro, Aveiro, Portugal
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25
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Complementary Roles of GADD34- and CReP-Containing Eukaryotic Initiation Factor 2α Phosphatases during the Unfolded Protein Response. Mol Cell Biol 2016; 36:1868-80. [PMID: 27161320 DOI: 10.1128/mcb.00190-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 04/27/2016] [Indexed: 02/02/2023] Open
Abstract
Phosphorylation of eukaryotic initiation factor 2α (eIF2α) controls transcriptome-wide changes in mRNA translation in stressed cells. While phosphorylated eIF2α (P-eIF2α) attenuates global protein synthesis, mRNAs encoding stress proteins are more efficiently translated. Two eIF2α phosphatases, containing GADD34 and CReP, catalyze P-eIF2α dephosphorylation. The current view of GADD34, whose transcription is stress induced, is that it functions in a feedback loop to resolve cell stress. In contrast, CReP, which is constitutively expressed, controls basal P-eIF2α levels in unstressed cells. Our studies show that GADD34 drives substantial changes in mRNA translation in unstressed cells, particularly targeting the secretome. Following activation of the unfolded protein response (UPR), rapid translation of GADD34 mRNA occurs and GADD34 is essential for UPR progression. In the absence of GADD34, eIF2α phosphorylation is persistently enhanced and the UPR translational program is significantly attenuated. This "stalled" UPR is relieved by the subsequent activation of compensatory mechanisms that include AKT-mediated suppression of PKR-like kinase (PERK) and increased expression of CReP mRNA, partially restoring protein synthesis. Our studies highlight the coordinate regulation of UPR by the GADD34- and CReP-containing eIF2α phosphatases to control cell viability.
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26
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Clavarino G, Adriouach S, Quesada JL, Clay M, Chevreau M, Trocmé C, Grange L, Gaudin P, Gatti E, Pierre P, Cesbron JY, Dumestre-Pérard C. Unfolded protein response gene GADD34 is overexpressed in rheumatoid arthritis and related to the presence of circulating anti-citrullinated protein antibodies. Autoimmunity 2016; 49:172-8. [DOI: 10.3109/08916934.2016.1138220] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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27
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Rojas M, Vasconcelos G, Dever TE. An eIF2α-binding motif in protein phosphatase 1 subunit GADD34 and its viral orthologs is required to promote dephosphorylation of eIF2α. Proc Natl Acad Sci U S A 2015; 112:E3466-75. [PMID: 26100893 PMCID: PMC4500263 DOI: 10.1073/pnas.1501557112] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Transient protein synthesis inhibition, mediated by phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2α), is an important protective mechanism cells use during stress conditions. Following relief of the stress, the growth arrest and DNA damage-inducible protein GADD34 associates with the broadly acting serine/threonine protein phosphatase 1 (PP1) to dephosphorylate eIF2α. Whereas the PP1-binding motif on GADD34 has been defined, it remains to be determined how GADD34 directs PP1 to specifically dephosphorylate eIF2α. In this report, we map a novel eIF2α-binding motif to the C terminus of GADD34 in a region distinct from where PP1 binds to GADD34. This motif is characterized by the consensus sequence Rx[Gnl]x(1-2)Wxxx[Arlv]x[Dn][Rg]xRFxx[Rlvk][Ivc], where capital letters are preferred and x is any residue. Point mutations altering the eIF2α-binding motif impair the ability of GADD34 to interact with eIF2α, promote eIF2α dephosphorylation, and suppress PKR toxicity in yeast. Interestingly, this eIF2α-docking motif is conserved among viral orthologs of GADD34, and is necessary for the proteins produced by African swine fever virus, Canarypox virus, and Herpes simplex virus to promote eIF2α dephosphorylation. Taken together, these data indicate that GADD34 and its viral orthologs direct specific dephosphorylation of eIF2α by interacting with both PP1 and eIF2α through independent binding motifs.
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Affiliation(s)
- Margarito Rojas
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Gabriel Vasconcelos
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Thomas E Dever
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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28
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Loveless TB, Topacio BR, Vashisht AA, Galaang S, Ulrich KM, Young BD, Wohlschlegel JA, Toczyski DP. DNA Damage Regulates Translation through β-TRCP Targeting of CReP. PLoS Genet 2015; 11:e1005292. [PMID: 26091241 PMCID: PMC4474599 DOI: 10.1371/journal.pgen.1005292] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 05/20/2015] [Indexed: 02/07/2023] Open
Abstract
The Skp1-Cul1-F box complex (SCF) associates with any one of a number of F box proteins, which serve as substrate binding adaptors. The human F box protein βTRCP directs the conjugation of ubiquitin to a variety of substrate proteins, leading to the destruction of the substrate by the proteasome. To identify βTRCP substrates, we employed a recently-developed technique, called Ligase Trapping, wherein a ubiquitin ligase is fused to a ubiquitin-binding domain to “trap” ubiquitinated substrates. 88% of the candidate substrates that we examined were bona fide substrates, comprising twelve previously validated substrates, eleven new substrates and three false positives. One βTRCP substrate, CReP, is a Protein Phosphatase 1 (PP1) specificity subunit that targets the translation initiation factor eIF2α to promote the removal of a stress-induced inhibitory phosphorylation and increase cap-dependent translation. We found that CReP is targeted by βTRCP for degradation upon DNA damage. Using a stable CReP allele, we show that depletion of CReP is required for the full induction of eIF2α phosphorylation upon DNA damage, and contributes to keeping the levels of translation low as cells recover from DNA damage. Approximately 600 human genes encode enzymes that act as ubiquitin ligases, which facilitate the transfer of the small protein ubiquitin to thousands of substrate proteins; “tagging” with ubiquitin often promotes the degradation of the substrate by the proteasome. In this paper, we adapt a technique called Ligase Trapping for use in mammalian cells. Ligase Trapping is a highly accurate method for determining which substrates are targeted by a ubiquitin ligase. Here we use it to identify new substrates of the human cell cycle regulator βTRCP. Our screen was indeed highly accurate, as we were able to validate 88% of the candidate substrates we identified by mass spectrometry. Some of these new substrates were unstable proteins that were stabilized by inhibition of βTRCP, or of the entire class of ubiquitin ligases of which βTRCP is a part. However, others appear to be stable or redundantly-targeted substrates, which have been more difficult to identify with current techniques. This suggests that Ligase Trapping will be able to reliably identify new substrates of human ubiquitin ligases. Further, one of the new βTRCP substrates, CReP, is specifically depleted upon DNA damage, and depletion of CReP contributes to inactivation of the translational machinery upon DNA damage.
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Affiliation(s)
- Theresa B. Loveless
- Department of Biochemistry and Biophysics, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Benjamin R. Topacio
- Department of Biochemistry and Biophysics, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Ajay A. Vashisht
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, California, United States of America
| | - Shastyn Galaang
- Department of Biochemistry and Biophysics, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Katie M. Ulrich
- Department of Biochemistry and Biophysics, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Brian D. Young
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, California, United States of America
| | - James A. Wohlschlegel
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, California, United States of America
| | - David P. Toczyski
- Department of Biochemistry and Biophysics, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
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29
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Choy MS, Yusoff P, Lee IC, Newton JC, Goh CW, Page R, Shenolikar S, Peti W. Structural and Functional Analysis of the GADD34:PP1 eIF2α Phosphatase. Cell Rep 2015; 11:1885-91. [PMID: 26095357 DOI: 10.1016/j.celrep.2015.05.043] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/27/2015] [Accepted: 05/27/2015] [Indexed: 11/27/2022] Open
Abstract
The attenuation of protein synthesis via the phosphorylation of eIF2α is a major stress response of all eukaryotic cells. The growth-arrest- and DNA-damage-induced transcript 34 (GADD34) bound to the serine/threonine protein phosphatase 1 (PP1) is the necessary eIF2α phosphatase complex that returns mammalian cells to normal protein synthesis following stress. The molecular basis by which GADD34 recruits PP1 and its substrate eIF2α are not fully understood, hindering our understanding of the remarkable selectivity of the GADD34:PP1 phosphatase for eIF2α. Here, we report detailed structural and functional analyses of the GADD34:PP1 holoenzyme and its recruitment of eIF2α. The data highlight independent interactions of PP1 and eIF2α with GADD34, demonstrating that GADD34 functions as a scaffold both in vitro and in cells. This work greatly enhances our molecular understanding of a major cellular eIF2α phosphatase and establishes the foundation for future translational work.
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Affiliation(s)
- Meng S Choy
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912, USA
| | - Permeen Yusoff
- Signature Research Program in Cardiovascular and Metabolic Disorders, Duke-NUS Graduate Medical School, Singapore 169857, Singapore
| | - Irene C Lee
- Signature Research Program in Neuroscience and Behavioral Disorders, Duke-NUS Graduate Medical School, Singapore 169857, Singapore
| | - Jocelyn C Newton
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Catherine W Goh
- Signature Research Program in Neuroscience and Behavioral Disorders, Duke-NUS Graduate Medical School, Singapore 169857, Singapore
| | - Rebecca Page
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Shirish Shenolikar
- Signature Research Program in Cardiovascular and Metabolic Disorders, Duke-NUS Graduate Medical School, Singapore 169857, Singapore; Signature Research Program in Neuroscience and Behavioral Disorders, Duke-NUS Graduate Medical School, Singapore 169857, Singapore.
| | - Wolfgang Peti
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912, USA; Department of Chemistry, Brown University, Providence, RI 02912, USA.
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30
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Dalet A, Gatti E, Pierre P. Integration of PKR-dependent translation inhibition with innate immunity is required for a coordinated anti-viral response. FEBS Lett 2015; 589:1539-45. [PMID: 25979169 DOI: 10.1016/j.febslet.2015.05.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 04/29/2015] [Accepted: 05/02/2015] [Indexed: 01/26/2023]
Abstract
Viral triggering of the innate immune response in infected cells aims at delaying viral replication and prevents tissue spreading. Viral replication is delayed by host protein synthesis inhibition and infected cell apoptosis on one hand, while infection spreading is controlled by the synthesis of specific proteins like type-I interferons (IFNs) and pro-inflammatory cytokines on the other hand. How do these two apparent conflicting responses cooperate within the same infected cells to mount effective defenses against pathogens? What are the molecules or the complexes resolving this contradiction over time? Some recent studies reveal unanticipated connections between innate immunity and stress pathways, giving important clues on how the cellular responses are orchestrated to limit infection efficiently.
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Affiliation(s)
- Alexandre Dalet
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2, Inserm, U1104, CNRS UMR7280, 13288 Marseille, France
| | - Evelina Gatti
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2, Inserm, U1104, CNRS UMR7280, 13288 Marseille, France; Institute for Research in Biomedicine - iBiMED and Aveiro Health Sciences Program, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Philippe Pierre
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2, Inserm, U1104, CNRS UMR7280, 13288 Marseille, France; Institute for Research in Biomedicine - iBiMED and Aveiro Health Sciences Program, University of Aveiro, 3810-193 Aveiro, Portugal.
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31
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Chen R, Rato C, Yan Y, Crespillo-Casado A, Clarke HJ, Harding HP, Marciniak SJ, Read RJ, Ron D. G-actin provides substrate-specificity to eukaryotic initiation factor 2α holophosphatases. eLife 2015; 4. [PMID: 25774600 PMCID: PMC4394352 DOI: 10.7554/elife.04871] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 03/12/2015] [Indexed: 12/29/2022] Open
Abstract
Dephosphorylation of eukaryotic translation initiation factor 2a (eIF2a) restores protein synthesis at the waning of stress responses and requires a PP1 catalytic subunit and a regulatory subunit, PPP1R15A/GADD34 or PPP1R15B/CReP. Surprisingly, PPP1R15-PP1 binary complexes reconstituted in vitro lacked substrate selectivity. However, selectivity was restored by crude cell lysate or purified G-actin, which joined PPP1R15-PP1 to form a stable ternary complex. In crystal structures of the non-selective PPP1R15B-PP1G complex, the functional core of PPP1R15 made multiple surface contacts with PP1G, but at a distance from the active site, whereas in the substrate-selective ternary complex, actin contributes to one face of a platform encompassing the active site. Computational docking of the N-terminal lobe of eIF2a at this platform placed phosphorylated serine 51 near the active site. Mutagenesis of predicted surface-contacting residues enfeebled dephosphorylation, suggesting that avidity for the substrate plays an important role in imparting specificity on the PPP1R15B-PP1G-actin ternary complex. DOI:http://dx.doi.org/10.7554/eLife.04871.001 For a cell to build a protein, it must first copy the instructions contained within a gene. A complex molecular machine called a ribosome then reads these instructions and translates them into a protein. This translation process involves a number of steps. Proteins called eukaryotic translation initiation factors (or eIFs for short) coordinate the first step in the process, which is known as ‘initiation’. The eIFs also provide the cell with ways to control how quickly it makes proteins. For example, when a cell is stressed, either by starvation or toxins, it adds a phosphate group onto part of an eIF protein, called eIF2α. This modification makes this eIF protein less able to initiate translation, and so the cell builds fewer proteins and conserves more of its resources during times of stress. Once the stressful conditions are over, the phosphate group is removed from eIF2α by an enzyme called a phosphatase. This phosphatase contains two subunits: one that recognizes eIF2α and another that removes the phosphate group. However, experiments that attempted to recreate this phosphatase activity using just these two subunits in a test tube failed to generate a working enzyme that specifically targeted the phosphate group of eIF2α. This suggests that in cells this enzyme contains an additional unknown subunit. Now, Chen et al. (and Chambers, Dalton et al.) report the identity of a ‘missing’ third subunit as a protein known as globular-actin or G-actin. First, Chen et al. looked at the three-dimensional structure of a two-subunit complex formed from the previously known subunits of the phosphatase enzyme, and confirmed that it could remove phosphate groups from a range of proteins and not just eIF2α. However, when a mixture of other proteins taken from mouse cells was added to this two-subunit complex, the complex could specifically remove the phosphate group on the eIF2α protein. Further experiments revealed that G-actin was the protein in the mixture that, when added to the two-subunit complex, made it specifically target the eIF2α protein. Chen et al. then used a combination of biochemical and structural biology techniques to investigate the phosphatase activity of the three-subunit complex. These findings suggest a plausible molecular mechanism by which the three-subunit complex becomes selective for its target, but further refinements to the structural work will be needed to critically test these suggestions. DOI:http://dx.doi.org/10.7554/eLife.04871.002
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Affiliation(s)
- Ruming Chen
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Cláudia Rato
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Yahui Yan
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Ana Crespillo-Casado
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Hanna J Clarke
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Heather P Harding
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Stefan J Marciniak
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Randy J Read
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - David Ron
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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Chambers JE, Dalton LE, Clarke HJ, Malzer E, Dominicus CS, Patel V, Moorhead G, Ron D, Marciniak SJ. Actin dynamics tune the integrated stress response by regulating eukaryotic initiation factor 2α dephosphorylation. eLife 2015; 4:e04872. [PMID: 25774599 PMCID: PMC4394351 DOI: 10.7554/elife.04872] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 03/12/2015] [Indexed: 12/23/2022] Open
Abstract
Four stress-sensing kinases phosphorylate the alpha subunit of eukaryotic translation initiation factor 2 (eIF2α) to activate the integrated stress response (ISR). In animals, the ISR is antagonised by selective eIF2α phosphatases comprising a catalytic protein phosphatase 1 (PP1) subunit in complex with a PPP1R15-type regulatory subunit. An unbiased search for additional conserved components of the PPP1R15-PP1 phosphatase identified monomeric G-actin. Like PP1, G-actin associated with the functional core of PPP1R15 family members and G-actin depletion, by the marine toxin jasplakinolide, destabilised the endogenous PPP1R15A-PP1 complex. The abundance of the ternary PPP1R15-PP1-G-actin complex was responsive to global changes in the polymeric status of actin, as was its eIF2α-directed phosphatase activity, while localised G-actin depletion at sites enriched for PPP1R15 enhanced eIF2α phosphorylation and the downstream ISR. G-actin's role as a stabilizer of the PPP1R15-containing holophosphatase provides a mechanism for integrating signals regulating actin dynamics with stresses that trigger the ISR.
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Affiliation(s)
- Joseph E Chambers
- Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust MRC Building, University of Cambridge, Cambridge, United Kingdom
| | - Lucy E Dalton
- Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust MRC Building, University of Cambridge, Cambridge, United Kingdom
| | - Hanna J Clarke
- Wellcome Trust MRC Building, University of Cambridge, Cambridge, United Kingdom
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Elke Malzer
- Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust MRC Building, University of Cambridge, Cambridge, United Kingdom
| | - Caia S Dominicus
- Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust MRC Building, University of Cambridge, Cambridge, United Kingdom
| | - Vruti Patel
- Cambridge Institute for Medical Research, Department of Medicine, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust MRC Building, University of Cambridge, Cambridge, United Kingdom
| | - Greg Moorhead
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - David Ron
- Wellcome Trust MRC Building, University of Cambridge, Cambridge, United Kingdom
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Stefan J Marciniak
- Wellcome Trust MRC Building, University of Cambridge, Cambridge, United Kingdom
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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Wu H, Wei L, Fan F, Ji S, Zhang S, Geng J, Hong L, Fan X, Chen Q, Tian J, Jiang M, Sun X, Jin C, Yin ZY, Liu Q, Zhang J, Qin F, Lin KH, Yu JS, Deng X, Wang HR, Zhao B, Johnson RL, Chen L, Zhou D. Integration of Hippo signalling and the unfolded protein response to restrain liver overgrowth and tumorigenesis. Nat Commun 2015; 6:6239. [PMID: 25695629 DOI: 10.1038/ncomms7239] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 01/08/2015] [Indexed: 12/21/2022] Open
Abstract
The role of the unfolded protein response (UPR) in tissue homeostasis remains largely unknown. Here we find that loss of Mst1/2, the mammalian Hippo orthologues, or their regulator WW45, leads to a remarkably enlarged endoplasmic reticulum (ER) size-associated UPR. Intriguingly, attenuation of the UPR by tauroursodeoxycholic acid (TUDCA) diminishes Mst1/2 mutant-driven liver overgrowth and tumorigenesis by promoting nuclear exit and degradation of Hippo downstream effector Yap. Yap is required for UPR activity and ER expansion to alleviate ER stress. During the adaptive stage of the UPR, PERK kinase-eIF2α axis activates Yap, while prolonged ER stress-induced Hippo signalling triggers assembly of the GADD34/PP1 complex in a negative feedback loop to inhibit Yap and promote apoptosis. Significantly, the deregulation of UPR signals associated with Yap activation is found in a substantial fraction of human hepatocellular carcinoma (HCC). Thus, we conclude Yap integrates Hippo and UPR signalling to control liver size and tumorigenesis.
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Affiliation(s)
- Hongtan Wu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Luyao Wei
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Fuqin Fan
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Suyuan Ji
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Shihao Zhang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Jing Geng
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Lixin Hong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Xin Fan
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Qinghua Chen
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Jing Tian
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Mingting Jiang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Xiufeng Sun
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Changnan Jin
- Department of Hepatology, Xiamen Hospital of Traditional Chinese Medicine, Xiamen, Fujian 361001, China
| | - Zhen-Yu Yin
- Department of Hepatobiliary Surgery, Zhongshan Hospital of Xiamen University, Xiamen, Fujian 361004, China
| | - Qingxu Liu
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Jinjia Zhang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Funiu Qin
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Kwang-Huei Lin
- College of Medicine, Chang Gung University, Kwei-Shan, Tao-Yang 333, Taiwan
| | - Jau-Song Yu
- College of Medicine, Chang Gung University, Kwei-Shan, Tao-Yang 333, Taiwan
| | - Xianming Deng
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Hong-Rui Wang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Bin Zhao
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Randy L Johnson
- Department of Biochemistry and Molecular Biology, University of Texas, M.D. Anderson Cancer Center, Houston, Texas 77030, USA
| | - Lanfen Chen
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
| | - Dawang Zhou
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiang'An district, Xiamen, Fujian 361102, China
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Ito S, Tanaka Y, Oshino R, Aiba K, Thanasegaran S, Nishio N, Isobe KI. GADD34 inhibits activation-induced apoptosis of macrophages through enhancement of autophagy. Sci Rep 2015; 5:8327. [PMID: 25659802 PMCID: PMC4321179 DOI: 10.1038/srep08327] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 01/15/2015] [Indexed: 11/09/2022] Open
Abstract
Autophagy is a common physiological function in all eukaryotes. The process is induced by depletion of nutrients including amino acids. GADD34 is expressed following DNA damage, ER stresses and amino acid deprivation. Here, we investigated the effects of GADD34 on autophagy and cell activation in macrophages. The deprivation of tyrosine and cysteine markedly induced the expression of GADD34 in macrophages. LPS stimulation combined with tyrosine/cysteine-deprivation initially activated macrophages, but then shifted to cell death in late phase of stimulation. When LPS stimulation was combined with tyrosine/cysteine-deprivation, a deficiency of GADD34 enhanced cell activation signaling such as Src-family, Erk1/2, p38 MAPK and Akt. In the late phase of stimulation, a deficiency of GADD34 increased apoptosis more than that in wild-type macrophages. Further we found that mTOR-S6K signaling was highly enhanced in GADD34-deficient macrophages compared with wild-type cells when cells were treated by LPS combined with tyrosine/cysteine-deprivation. LC3-II was increased by LPS stimulation combined with tyrosine/cysteine-deprivation. Defective GADD34 reduced LC3-II and autophagosome formation induced by LPS-stimulation and tyrosine/cysteine-deprivation compared with that seen in wild-type macrophages. These results indicates that GADD34 enhances autophagy and suppresses apoptosis stimulated by LPS combined with amino acid deprivation through regulation of mTOR signaling pathway in macrophages.
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Affiliation(s)
- Sachiko Ito
- Department of Immunology, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Yuriko Tanaka
- Department of Immunology, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Reina Oshino
- Department of Immunology, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Keiko Aiba
- Department of Immunology, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Suganya Thanasegaran
- Department of Immunology, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Naomi Nishio
- Department of Immunology, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
| | - Ken-ichi Isobe
- Department of Immunology, Nagoya University Graduate School of Medicine, 65 Turumai-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan
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35
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Negative regulation of GADD34 on myofibroblasts during cutaneous wound healing. BIOMED RESEARCH INTERNATIONAL 2014; 2014:137049. [PMID: 25210702 PMCID: PMC4156997 DOI: 10.1155/2014/137049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 08/04/2014] [Accepted: 08/05/2014] [Indexed: 01/15/2023]
Abstract
The growth arrest and DNA damage-inducible protein, GADD34, has been proved to be involved in TGF-β signaling pathway and correlates with cell death, which are two important mechanisms in regulating myofibroblast differentiation and apoptosis during tissue repair. But roles of GADD34 in myofibroblasts differentiation and apoptosis remain unknown. To investigate the function of GADD34 in these processes, we subjected WT and GADD34−/− mice to dermal wound healing. Here we show that GADD34−/− mice exhibited accelerated wound closure compared with WT mice. In addition, GADD34−/− mice showed increased number of myofibroblasts, elevated collagen production, and decreased cell apoptosis during wound healing. Moreover, we found that GADD34−/− mice showed increased phosphorylation of Smad3 and lower level of cleaved caspase-3. Thus these results indicate that GADD34 appears to suppress myofibroblast differentiation through inhibiting Smad3-dependent TGFβ signal pathway and promote its apoptosis by activating caspase-3 pathway.
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36
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Hua KT, Wang MY, Chen MW, Wei LH, Chen CK, Ko CH, Jeng YM, Sung PL, Jan YH, Hsiao M, Kuo ML, Yen ML. The H3K9 methyltransferase G9a is a marker of aggressive ovarian cancer that promotes peritoneal metastasis. Mol Cancer 2014; 13:189. [PMID: 25115793 PMCID: PMC4260797 DOI: 10.1186/1476-4598-13-189] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 08/07/2014] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Ovarian cancer (OCa) peritoneal metastasis is the leading cause of cancer-related deaths in women with limited therapeutic options available for treating it and poor prognosis, as the underlying mechanism is not fully understood. METHOD The clinicopathological correlation of G9a expression was assessed in tumor specimens of ovarian cancer patients. Knockdown or overexpression of G9a in ovarian cancer cell lines was analysed with regard to its effect on adhesion, migration, invasion and anoikis-resistance. In vivo biological functions of G9a were tested by i.p. xenograft ovarian cancer models. Microarray and quantitative RT-PCR were used to analyze G9a-regulated downstream target genes. RESULTS We found that the expression of histone methyltransferase G9a was highly correlated with late stage, high grade, and serous-type OCa. Higher G9a expression predicted a shorter survival in ovarian cancer patients. Furthermore, G9a expression was higher in metastatic lesions compared with their corresponding ovarian primary tumors. Knockdown of G9a expression suppressed prometastatic cellular activities including adhesion, migration, invasion and anoikis-resistance of ovarian cancer cell lines, while G9a over-expression promoted these cellular properties. G9a depletion significantly attenuated the development of ascites and tumor nodules in a peritoneal dissemination model. Importantly, microarray and quantitative RT-PCR analysis revealed that G9a regulates a cohort of tumor suppressor genes including CDH1, DUSP5, SPRY4, and PPP1R15A in ovarian cancer. Expression of these genes was also inversely correlated with G9a expression in OCa specimens. CONCLUSION We propose that G9a contributes to multiple steps of ovarian cancer metastasis and represents a novel target to combat this deadly disease.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Min-Liang Kuo
- Graduate Institute of Toxicology, National Taiwan University College of Medicine, Taipei, Taiwan.
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Pathological stress granules in Alzheimer's disease. Brain Res 2014; 1584:52-8. [PMID: 25108040 DOI: 10.1016/j.brainres.2014.05.052] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/22/2014] [Accepted: 05/02/2014] [Indexed: 02/01/2023]
Abstract
A feature of neurodegenerative disease is the accumulation of insoluble protein aggregates in the brain. In some conditions, including Amyotrophic Lateral Sclerosis and Frontotemporal lobar degeneration, the primary aggregating entities are RNA binding proteins. Through regulated prion-like assembly, RNA binding proteins serve many functions in RNA metabolism that are essential for the healthy maintenance of cells of the central nervous system. Those RNA binding proteins that are the core nucleating factors of stress granules (SGs), including TIA-1, TIAR, TTP and G3BP1, are also found in the pathological lesions of other neurological conditions, such as Alzheimer's disease, where the hallmark aggregating protein is not an RNA binding protein. This discovery suggests that the regulated cellular pathway, which utilizes assembly of RNA binding proteins to package and silence mRNAs during stress, may be integral in the aberrant pathological protein aggregation that occurs in numerous neurodegenerative conditions.
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38
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Besche HC, Sha Z, Kukushkin NV, Peth A, Hock EM, Kim W, Gygi S, Gutierrez JA, Liao H, Dick L, Goldberg AL. Autoubiquitination of the 26S proteasome on Rpn13 regulates breakdown of ubiquitin conjugates. EMBO J 2014; 33:1159-76. [PMID: 24811749 PMCID: PMC4193922 DOI: 10.1002/embj.201386906] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 03/12/2014] [Accepted: 04/01/2014] [Indexed: 11/09/2022] Open
Abstract
Degradation rates of most proteins in eukaryotic cells are determined by their rates of ubiquitination. However, possible regulation of the proteasome's capacity to degrade ubiquitinated proteins has received little attention, although proteasome inhibitors are widely used in research and cancer treatment. We show here that mammalian 26S proteasomes have five associated ubiquitin ligases and that multiple proteasome subunits are ubiquitinated in cells, especially the ubiquitin receptor subunit, Rpn13. When proteolysis is even partially inhibited in cells or purified 26S proteasomes with various inhibitors, Rpn13 becomes extensively and selectively poly-ubiquitinated by the proteasome-associated ubiquitin ligase, Ube3c/Hul5. This modification also occurs in cells during heat-shock or arsenite treatment, when poly-ubiquitinated proteins accumulate. Rpn13 ubiquitination strongly decreases the proteasome's ability to bind and degrade ubiquitin-conjugated proteins, but not its activity against peptide substrates. This autoinhibitory mechanism presumably evolved to prevent binding of ubiquitin conjugates to defective or stalled proteasomes, but this modification may also be useful as a biomarker indicating the presence of proteotoxic stress and reduced proteasomal capacity in cells or patients.
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Affiliation(s)
| | - Zhe Sha
- Harvard Medical School, Boston, MA, USA
| | | | | | | | - Woong Kim
- Harvard Medical School, Boston, MA, USA
| | | | | | - Hua Liao
- Millennium Pharmaceuticals Inc., Cambridge, MA, USA
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Chen R, Huo L, Shi X, Bai R, Zhang Z, Zhao Y, Chang Y, Chen C. Endoplasmic reticulum stress induced by zinc oxide nanoparticles is an earlier biomarker for nanotoxicological evaluation. ACS NANO 2014; 8:2562-2574. [PMID: 24490819 DOI: 10.1021/nn406184r] [Citation(s) in RCA: 174] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Zinc oxide nanoparticles (ZnO NPs) have been widely used in cosmetics and sunscreens, advanced textiles, self-charging and electronic devices; the potential for human exposure and the health impact at each stage of their manufacture and use are attracting great concerns. In addition to pulmonary damage, nanoparticle exposure is also strongly correlated with the increase in incidences of cardiovascular diseases; however, their toxic potential remains largely unclear. Herein, we investigated the cellular responses and endoplasmatic reticulum (ER) stress induced by ZnO NPs in human umbilical vein endothelial cells (HUVECs) in comparison with the Zn2+ ions and CeO2 NPs. We found that the dissolved zinc ion was the most significant factor for cytotoxicity in HUVECs. More importantly, ZnO NPs at noncytotoxic concentration, but not CeO2 NPs, can induce significant cellular ER stress response with higher expression of spliced xbp-1, chop, and caspase-12 at the mRNA level, and associated ER marker proteins including BiP, Chop, GADD34, p-PERK, p-eIF2α, and cleaved Caspase-12 at the protein levels. Moreover, ER stress was widely activated after treatment with ZnO NPs, while six of 84 marker genes significantly increased. ER stress response is a sensitive marker for checking the interruption of ER homeostasis by ZnO NPs. Furthermore, higher dosage of ZnO NPs (240 μM) quickly rendered ER stress response before inducing apoptosis. These results demonstrate that ZnO NPs activate ER stress-responsive pathway and the ER stress response might be used as an earlier and sensitive end point for nanotoxicological study.
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Affiliation(s)
- Rui Chen
- CAS Key Lab for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience & Technology of China , Beijing 100090, P. R. China
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Protein phosphatase PP1/GLC7 interaction domain in yeast eIF2γ bypasses targeting subunit requirement for eIF2α dephosphorylation. Proc Natl Acad Sci U S A 2014; 111:E1344-53. [PMID: 24706853 DOI: 10.1073/pnas.1400129111] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Whereas the protein kinases GCN2, HRI, PKR, and PERK specifically phosphorylate eukaryotic translation initiation factor 2 (eIF2α) on Ser51 to regulate global and gene-specific mRNA translation, eIF2α is dephosphorylated by the broadly acting serine/threonine protein phosphatase 1 (PP1). In mammalian cells, the regulatory subunits GADD34 and CReP target PP1 to dephosphorylate eIF2α; however, as there are no homologs of these targeting subunits in yeast, it is unclear how GLC7, the functional homolog of PP1 in yeast, is recruited to dephosphorylate eIF2α. Here, we show that a novel N-terminal extension on yeast eIF2γ contains a PP1-binding motif (KKVAF) that enables eIF2γ to pull down GLC7 and target it to dephosphorylate eIF2α. Truncation or point mutations designed to eliminate the KKVAF motif in eIF2γ impair eIF2α dephosphorylation in vivo and in vitro and enhance expression of GCN4. Replacement of the N terminus of eIF2γ with the GLC7-binding domain from GAC1 or fusion of heterologous dimerization domains to eIF2γ and GLC7, respectively, maintained eIF2α phosphorylation at basal levels. Taken together, these results indicate that, in contrast to the paradigm of distinct PP1-targeting or regulatory subunits, the unique N terminus of yeast eIF2γ functions in cis to target GLC7 to dephosphorylate eIF2α.
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41
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Dynamics of unfolded protein response in recombinant CHO cells. Cytotechnology 2014; 67:237-54. [PMID: 24504562 DOI: 10.1007/s10616-013-9678-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 12/14/2013] [Indexed: 10/25/2022] Open
Abstract
Genes in the protein secretion pathway have been targeted to increase productivity of monoclonal antibodies in Chinese hamster ovary cells. The results have been highly variable depending on the cell type and the relative amount of recombinant and target proteins. This paper presents a comprehensive study encompassing major components of the protein processing pathway in the endoplasmic reticulum (ER) to elucidate its role in recombinant cells. mRNA profiles of all major ER chaperones and unfolded protein response (UPR) pathway genes are measured at a series of time points in a high-producing cell line under the dynamic environment of a batch culture. An initial increase in IgG heavy chain mRNA levels correlates with an increase in productivity. We observe a parallel increase in the expression levels of majority of chaperones. The chaperone levels continue to increase until the end of the batch culture. In contrast, calreticulin and ERO1-L alpha, two of the lowest expressed genes exhibit transient time profiles, with peak induction on day 3. In response to increased ER stress, both the GCN2/PKR-like ER kinase and inositol-requiring enzyme-1alpha (Ire1α) signalling branch of the UPR are upregulated. Interestingly, spliced X-Box binding protein 1 (XBP1s) transcription factor from Ire1α pathway is detected from the beginning of the batch culture. Comparison with the expression levels in a low producer, show much lower induction at the end of the exponential growth phase. Thus, the unfolded protein response strongly correlates with the magnitude and timing of stress in the course of the batch culture.
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Zhou W, Jeyaraman K, Yusoff P, Shenolikar S. Phosphorylation at tyrosine 262 promotes GADD34 protein turnover. J Biol Chem 2013; 288:33146-55. [PMID: 24092754 DOI: 10.1074/jbc.m113.504407] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In mammalian cells, metabolic and environmental stress increases the phosphorylation of the eukaryotic translational initiation factor, eIF2α, and attenuates global protein synthesis. Subsequent transcriptional activation of GADD34 assembles an eIF2α phosphatase that feeds back to restore mRNA translation. Active proteasomal degradation of GADD34 protein then reestablishes the sensitivity of cells to subsequent bouts of stress. Mass spectrometry established GADD34 phosphorylation on multiple serines, threonines, and tyrosines. Phosphorylation at tyrosine 262 enhanced the rate of the GADD34 protein turnover. Substrate-trapping studies identified TC-PTP (PTPN2) as a potential GADD34 phosphatase, recognizing phosphotyrosine 262. Reduced GADD34 protein levels in TC-PTP-null MEFs following ER stress emphasized the importance of TC-PTP in determining the cellular levels of GADD34 protein. The susceptibility of TC-PTP-null MEFs to ER stress-induced apoptosis was significantly ameliorated by ectopic expression of GADD34. The data suggested that GADD34 phosphorylation on tyrosine 262 modulates endoplasmic reticulum stress signaling and cell fate.
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Affiliation(s)
- Wei Zhou
- From the Signature Research Programs in Cardiovascular and Metabolic Disorders and
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43
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Malzer E, Szajewska-Skuta M, Dalton LE, Thomas SE, Hu N, Skaer H, Lomas DA, Crowther DC, Marciniak SJ. Coordinate regulation of eIF2α phosphorylation by PPP1R15 and GCN2 is required during Drosophila development. J Cell Sci 2013; 126:1406-15. [PMID: 23418347 DOI: 10.1242/jcs.117614] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) by the kinase GCN2 attenuates protein synthesis during amino acid starvation in yeast, whereas in mammals a family of related eIF2α kinases regulate translation in response to a variety of stresses. Unlike single-celled eukaryotes, mammals also possess two specific eIF2α phosphatases, PPP1R15a and PPP1R15b, whose combined deletion leads to a poorly understood early embryonic lethality. We report the characterisation of the first non-mammalian eIF2α phosphatase and the use of Drosophila to dissect its role during development. The Drosophila protein demonstrates features of both mammalian proteins, including limited sequence homology and association with the endoplasmic reticulum. Of note, although this protein is not transcriptionally regulated, its expression is controlled by the presence of upstream open reading frames in its 5'UTR, enabling induction in response to eIF2α phosphorylation. Moreover, we show that its expression is necessary for embryonic and larval development and that this is to oppose the inhibitory effects of GCN2 on anabolic growth.
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Affiliation(s)
- Elke Malzer
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research (CIMR), Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
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Ruggieri A, Dazert E, Metz P, Hofmann S, Bergeest JP, Mazur J, Bankhead P, Hiet MS, Kallis S, Alvisi G, Samuel CE, Lohmann V, Kaderali L, Rohr K, Frese M, Stoecklin G, Bartenschlager R. Dynamic oscillation of translation and stress granule formation mark the cellular response to virus infection. Cell Host Microbe 2013; 12:71-85. [PMID: 22817989 DOI: 10.1016/j.chom.2012.05.013] [Citation(s) in RCA: 151] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 04/19/2012] [Accepted: 05/18/2012] [Indexed: 12/24/2022]
Abstract
Virus infection-induced global protein synthesis suppression is linked to assembly of stress granules (SGs), cytosolic aggregates of stalled translation preinitiation complexes. To study long-term stress responses, we developed an imaging approach for extended observation and analysis of SG dynamics during persistent hepatitis C virus (HCV) infection. In combination with type 1 interferon, HCV infection induces highly dynamic assembly/disassembly of cytoplasmic SGs, concomitant with phases of active and stalled translation, delayed cell division, and prolonged cell survival. Double-stranded RNA (dsRNA), independent of viral replication, is sufficient to trigger these oscillations. Translation initiation factor eIF2α phosphorylation by protein kinase R mediates SG formation and translation arrest. This is antagonized by the upregulation of GADD34, the regulatory subunit of protein phosphatase 1 dephosphorylating eIF2α. Stress response oscillation is a general mechanism to prevent long-lasting translation repression and a conserved host cell reaction to multiple RNA viruses, which HCV may exploit to establish persistence.
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Affiliation(s)
- Alessia Ruggieri
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Germany
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45
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Kinases, phosphatases and proteases during sperm capacitation. Cell Tissue Res 2012; 349:765-82. [DOI: 10.1007/s00441-012-1370-3] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 02/07/2012] [Indexed: 12/17/2022]
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Clavarino G, Cláudio N, Dalet A, Terawaki S, Couderc T, Chasson L, Ceppi M, Schmidt EK, Wenger T, Lecuit M, Gatti E, Pierre P. Protein phosphatase 1 subunit Ppp1r15a/GADD34 regulates cytokine production in polyinosinic:polycytidylic acid-stimulated dendritic cells. Proc Natl Acad Sci U S A 2012; 109:3006-3011. [PMID: 22315398 PMCID: PMC3286954 DOI: 10.1073/pnas.1104491109] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023] Open
Abstract
In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation that exhibits specific mechanisms to control the immune response. Here we show that in response to polyriboinosinic:polyribocytidylic acid (pI:C), DCs mount a specific integrated stress response during which the transcription factor ATF4 and the growth arrest and DNA damage-inducible protein 34 (GADD34/Ppp1r15a), a phosphatase 1 (PP1) cofactor, are expressed. In agreement with increased GADD34 levels, an extensive dephosphorylation of the translation initiation factor eIF2α was observed during DC activation. Unexpectedly, although DCs display an unusual resistance to protein synthesis inhibition induced in response to cytosolic dsRNA, GADD34 expression did not have a major impact on protein synthesis. GADD34, however, was shown to be required for normal cytokine production both in vitro and in vivo. These observations have important implications in linking further pathogen detection with the integrated stress response pathways.
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Affiliation(s)
- Giovanna Clavarino
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Nuno Cláudio
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Alexandre Dalet
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Seigo Terawaki
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Thérèse Couderc
- Microbes and Host Barriers Group, Institut Pasteur, 75015 Paris, France
- INSERM, Equipe avenir U604, 75015 Paris, France; and
| | - Lionel Chasson
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Maurizio Ceppi
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Enrico K. Schmidt
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Till Wenger
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Marc Lecuit
- Microbes and Host Barriers Group, Institut Pasteur, 75015 Paris, France
- INSERM, Equipe avenir U604, 75015 Paris, France; and
- Service des Maladies Infectieuses et Tropicales, Université Paris Descartes, Hôpital Necker-Enfants malades, Assistance Publique-Hôpitaux de Paris, 75015 Paris, France
| | - Evelina Gatti
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
| | - Philippe Pierre
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille University, 13288 Marseille, France
- Institut National de la Santé et de la Recherche Médicale (INSERM), U631, 13288 Marseille, France
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6102, 13288 Marseille, France
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Fullwood MJ, Zhou W, Shenolikar S. Targeting Phosphorylation of Eukaryotic Initiation Factor-2α to Treat Human Disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 106:75-106. [DOI: 10.1016/b978-0-12-396456-4.00005-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Dalton LE, Healey E, Irving J, Marciniak SJ. Phosphoproteins in stress-induced disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 106:189-221. [PMID: 22340719 DOI: 10.1016/b978-0-12-396456-4.00003-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The integrated stress response (ISR) is an evolutionarily conserved homeostatic program activated by specific pathological states. These include amino acid deprivation, viral infection, iron deficiency, and the misfolding of proteins within the endoplasmic reticulum (ER), the so-called ER stress. Although apparently disparate, each of these stresses induces phosphorylation of a translation initiation factor, eIF2α, to attenuate new protein translation while simultaneously triggering a transcriptional program. This is achieved by four homologous stress-sensing kinases: GCN2, PKR, HRI, and PERK. In addition to these kinases, mammals possess two specific eIF2α phosphatases, GADD34 and CReP, which play crucial roles in the recovery of protein synthesis following the initial insult. They are not only important in embryonic development but also appear to play important roles in disease, particularly cancer. In this chapter, we discuss each of the eIF2α kinases, in turn, with particular emphasis on their regulation and the new insights provided by recent structural studies. We also discuss the potential for developing novel drug therapies that target the ISR.
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Affiliation(s)
- Lucy E Dalton
- Division of Respiratory Medicine, Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Cambridge, United Kingdom
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Ratchford SM, Bailey AN, Senesac HA, Hocker AD, Smolkowski K, Lantz BA, Jewett BA, Gilbert JS, Dreyer HC. Proteins regulating cap-dependent translation are downregulated during total knee arthroplasty. Am J Physiol Regul Integr Comp Physiol 2011; 302:R702-11. [PMID: 22204954 DOI: 10.1152/ajpregu.00601.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Total knee arthroplasty (TKA) utilizes a tourniquet to reduce blood loss, maintain a clear surgical "bloodless" field, and to ensure proper bone-implant cementing. In 2007, over 600,000 TKAs were performed in the United States, and this number is projected to increase to 3.48 million procedures performed annually by 2030. The acute effects of tourniquet-induced ischemia-reperfusion (I/R) on human skeletal muscle cells are poorly understood and require critical investigation, as muscle atrophy following this surgery is rapid and represents the most significant clinical barrier to long-term normalization of physical function. To determine the acute effects of I/R on skeletal muscle cells, biopsies were obtained at baseline, maximal ischemia (prior to tourniquet release), and reperfusion (following tourniquet release). Quadriceps volume was determined before and 2 wk post-TKA by MRI. We measured a 36% decrease in phosphorylation of Akt Ser(473) during ischemia and 37% during reperfusion (P < 0.05). 4E-BP1 Thr(37/46) phosphorylation decreased 29% during ischemia and 22% during reperfusion (P < 0.05). eEF2 Thr(56) phosphorylation increased 25% during ischemia and 43% during reperfusion (P < 0.05). Quadriceps volume decreased 12% in the TKA leg (P < 0.05) and tended to decrease (6%) in the contralateral leg (P = 0.1). These data suggest cap-dependent translation initiation, and elongation may be inhibited during and after TKA surgery. We propose that cap-dependent translational events occurring during surgery may precipitate postoperative changes in muscle cells that contribute to the etiology of muscle atrophy following TKA.
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Affiliation(s)
- Stephen M Ratchford
- Department of Human Physiology, University of Oregon, Eugene, Oregon 97403-1240, USA
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50
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Fullwood MJ, Lee J, Lin L, Li G, Huss M, Ng P, Sung WK, Shenolikar S. Next-generation sequencing of apoptotic DNA breakpoints reveals association with actively transcribed genes and gene translocations. PLoS One 2011; 6:e26054. [PMID: 22087219 PMCID: PMC3210745 DOI: 10.1371/journal.pone.0026054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 09/16/2011] [Indexed: 12/31/2022] Open
Abstract
DNA fragmentation is a well-recognized hallmark of apoptosis. However, the precise DNA sequences cleaved during apoptosis triggered by distinct mechanisms remain unclear. We used next-generation sequencing of DNA fragments generated in Actinomycin D-treated human HL-60 leukemic cells to generate a high-throughput, global map of apoptotic DNA breakpoints. These data highlighted that DNA breaks are non-random and show a significant association with active genes and open chromatin regions. We noted that transcription factor binding sites were also enriched within a fraction of the apoptotic breakpoints. Interestingly, extensive apoptotic cleavage was noted within genes that are frequently translocated in human cancers. We speculate that the non-random fragmentation of DNA during apoptosis may contribute to gene translocations and the development of human cancers.
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Affiliation(s)
- Melissa J. Fullwood
- A*STAR-Duke-NUS Neuroscience Partnership, Duke-NUS Graduate Medical School Singapore, Singapore, Singapore
- Genome Institute of Singapore, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
| | - Joanne Lee
- Genome Institute of Singapore, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Lifang Lin
- A*STAR-Duke-NUS Neuroscience Partnership, Duke-NUS Graduate Medical School Singapore, Singapore, Singapore
| | - Guoliang Li
- Genome Institute of Singapore, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | | | | | - Wing-Kin Sung
- Genome Institute of Singapore, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Shirish Shenolikar
- Signature Research Programs in Cardiovascular and Metabolic Disorders and Neuroscience and Behavioral Disorders, Duke-NUS Graduate Medical School Singapore, Singapore, Singapore
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
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