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Patel V, Bidault G, Chambers JE, Carobbio S, Everden AJT, Garcés C, Dalton LE, Gribble FM, Vidal-Puig A, Marciniak SJ. Inactivation of Ppp1r15a minimises weight gain and insulin resistance during caloric excess in female mice. Sci Rep 2019; 9:2903. [PMID: 30814564 PMCID: PMC6393541 DOI: 10.1038/s41598-019-39562-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 01/09/2019] [Indexed: 02/02/2023] Open
Abstract
Phosphorylation of the translation initiation factor eIF2α within the mediobasal hypothalamus is known to suppress food intake, but the role of the eIF2α phosphatases in regulating body weight is poorly understood. Mice deficient in active PPP1R15A, a stress-inducible eIF2α phosphatase, are healthy and more resistant to endoplasmic reticulum stress than wild type controls. We report that when female Ppp1r15a mutant mice are fed a high fat diet they gain less weight than wild type littermates owing to reduced food intake. This results in healthy leaner Ppp1r15a mutant animals with reduced hepatic steatosis and improved insulin sensitivity, albeit with a possible modest defect in insulin secretion. By contrast, no weight differences are observed between wild type and Ppp1r15a deficient mice fed a standard diet. We conclude that female mice lacking the C-terminal PP1-binding domain of PPP1R15A show reduced dietary intake and preserved glucose tolerance. Our data indicate that this results in reduced weight gain and protection from diet-induced obesity.
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Affiliation(s)
- Vruti Patel
- 0000000121885934grid.5335.0Cambridge Institute for Medical Research (CIMR), University of Cambridge Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY UK ,0000000121885934grid.5335.0Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Rd, Cambridge, CB2 0SP UK
| | - Guillaume Bidault
- 0000 0004 0622 5016grid.120073.7Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, CB2 0QQ UK
| | - Joseph E. Chambers
- 0000000121885934grid.5335.0Cambridge Institute for Medical Research (CIMR), University of Cambridge Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY UK
| | - Stefania Carobbio
- 0000 0004 0622 5016grid.120073.7Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, CB2 0QQ UK
| | - Angharad J. T. Everden
- 0000000121885934grid.5335.0Cambridge Institute for Medical Research (CIMR), University of Cambridge Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY UK
| | - Concepción Garcés
- 0000000121885934grid.5335.0Cambridge Institute for Medical Research (CIMR), University of Cambridge Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY UK
| | - Lucy E. Dalton
- 0000000121885934grid.5335.0Cambridge Institute for Medical Research (CIMR), University of Cambridge Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY UK
| | - Fiona M. Gribble
- 0000 0004 0622 5016grid.120073.7Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, CB2 0QQ UK
| | - Antonio Vidal-Puig
- 0000 0004 0622 5016grid.120073.7Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge, CB2 0QQ UK ,0000 0004 0427 7672grid.52788.30Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, CB10 1SA UK
| | - Stefan J. Marciniak
- 0000000121885934grid.5335.0Cambridge Institute for Medical Research (CIMR), University of Cambridge Wellcome Trust/MRC Building, Hills Road, Cambridge, CB2 0XY UK ,0000000121885934grid.5335.0Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Hills Rd, Cambridge, CB2 0SP UK
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Song P, Yang S, Hua H, Zhang H, Kong Q, Wang J, Luo T, Jiang Y. The regulatory protein GADD34 inhibits TRAIL-induced apoptosis via TRAF6/ERK-dependent stabilization of myeloid cell leukemia 1 in liver cancer cells. J Biol Chem 2019; 294:5945-5955. [PMID: 30782845 DOI: 10.1074/jbc.ra118.006029] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 02/09/2019] [Indexed: 02/05/2023] Open
Abstract
GADD34 (growth arrest and DNA damage-inducible gene 34) plays a critical role in responses to DNA damage and endoplasmic reticulum stress. GADD34 has opposing effects on different stimuli-induced cell apoptosis events, but the reason for this is unclear. Here, using immunoblotting analyses and various molecular genetic approaches in HepG2 and SMMC-7721 cells, we demonstrate that GADD34 protects hepatocellular carcinoma (HCC) cells from tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis by stabilizing a BCL-2 family member, myeloid cell leukemia 1 (MCL-1). We found that GADD34 knockdown decreased MCL-1 levels and that GADD34 overexpression up-regulated MCL-1 expression in HCC cells. GADD34 did not affect MCL-1 transcription but enhanced MCL-1 protein stability. The proteasome inhibitor MG132 abrogated GADD34 depletion-induced MCL-1 down-regulation, suggesting that GADD34 inhibits the proteasomal degradation of MCL-1. Furthermore, GADD34 overexpression promoted extracellular signal-regulated kinase (ERK) phosphorylation through a signaling axis that consists of the E3 ubiquitin ligase tumor necrosis factor receptor-associated factor 6 (TRAF6) and transforming growth factor-β-activated kinase 1 (MAP3K7)-binding protein 1 (TAB1), which mediated the up-regulation of MCL-1 by GADD34. Of note, TRAIL up-regulated both GADD34 and MCL-1 levels, and knockdown of GADD34 and TRAF6 suppressed the induction of MCL-1 by TRAIL. Correspondingly, GADD34 knockdown potentiated TRAIL-induced apoptosis, and MCL-1 overexpression rescued TRAIL-treated and GADD34-depleted HCC cells from cell death. Taken together, these findings suggest that GADD34 inhibits TRAIL-induced HCC cell apoptosis through TRAF6- and ERK-mediated stabilization of MCL-1.
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Affiliation(s)
- Peiying Song
- From the State Key Laboratory of Biotherapy, Section of Oncogene, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041
| | - Songpeng Yang
- From the State Key Laboratory of Biotherapy, Section of Oncogene, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041
| | - Hui Hua
- the Laboratory of Stem Cell Biology, West China Hospital, Chengdu 610041
| | - Hongying Zhang
- From the State Key Laboratory of Biotherapy, Section of Oncogene, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041
| | - Qingbin Kong
- From the State Key Laboratory of Biotherapy, Section of Oncogene, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041
| | - Jiao Wang
- the School of Basic Medicine, Chengdu University of Traditional Chinese Medicine, Chengdu 610075
| | - Ting Luo
- the Cancer Center, West China Hospital, Chengdu 610041, China
| | - Yangfu Jiang
- From the State Key Laboratory of Biotherapy, Section of Oncogene, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu 610041.
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Krokowski D, Jobava R, Guan BJ, Farabaugh K, Wu J, Majumder M, Bianchi MG, Snider MD, Bussolati O, Hatzoglou M. Coordinated Regulation of the Neutral Amino Acid Transporter SNAT2 and the Protein Phosphatase Subunit GADD34 Promotes Adaptation to Increased Extracellular Osmolarity. J Biol Chem 2015; 290:17822-17837. [PMID: 26041779 DOI: 10.1074/jbc.m114.636217] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Indexed: 02/04/2023] Open
Abstract
Cells respond to shrinkage induced by increased extracellular osmolarity via programmed changes in gene transcription and mRNA translation. The immediate response to this stress includes the induction of expression of the neutral amino acid transporter SNAT2. Increased SNAT2-mediated uptake of neutral amino acids is an essential adaptive mechanism for restoring cell volume. In contrast, stress-induced phosphorylation of the α subunit of the translation initiation factor eIF2 (eIF2α) can promote apoptosis. Here we show that the response to mild hyperosmotic stress involves regulation of the phosphorylation of eIF2α by increased levels of GADD34, a regulatory subunit of protein phosphatase 1 (PP1). The induction of GADD34 was dependent on transcriptional control by the c-Jun-binding cAMP response element in the GADD34 gene promoter and posttranscriptional stabilization of its mRNA. This mechanism differs from the regulation of GADD34 expression by other stresses that involve activating transcription factor 4 (ATF4). ATF4 was not translated during hyperosmotic stress despite an increase in eIF2α phosphorylation. The SNAT2-mediated increase in amino acid uptake was enhanced by increased GADD34 levels in a manner involving decreased eIF2α phosphorylation. It is proposed that the induction of the SNAT2/GADD34 axis enhances cell survival by promoting the immediate adaptive response to stress.
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Affiliation(s)
- Dawid Krokowski
- Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106.
| | - Raul Jobava
- Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Bo-Jhih Guan
- Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Kenneth Farabaugh
- Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Jing Wu
- Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Mithu Majumder
- Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Massimiliano G Bianchi
- Department of Biomedical, Biotechnological, and Translational Sciences, University of Parma, 43100 Parma, Italy
| | - Martin D Snider
- Departments of Biochemistry, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Ovidio Bussolati
- Department of Biomedical, Biotechnological, and Translational Sciences, University of Parma, 43100 Parma, Italy
| | - Maria Hatzoglou
- Departments of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106.
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