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Katz LS, Brill G, Wang P, Lambertini L, Zhang P, Haldeman JM, Liu H, Newgard CB, Stewart AF, Garcia-Ocaña A, Scott DK. Transcriptional activation of the Myc gene by glucose in β-cells requires a ChREBP-dependent 3-D chromatin interaction between the Myc and Pvt1 genes. Mol Metab 2024; 79:101848. [PMID: 38042369 PMCID: PMC10714240 DOI: 10.1016/j.molmet.2023.101848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 11/14/2023] [Accepted: 11/28/2023] [Indexed: 12/04/2023] Open
Abstract
OBJECTIVE All forms of diabetes result from insufficient functional β-cell mass. Thus, achieving the therapeutic goal of expanding β-cell mass requires a better mechanistic understanding of how β-cells proliferate. Glucose is a natural β-cell mitogen that mediates its effects in part through the glucose-responsive transcription factor, carbohydrate response element binding protein (ChREBP) and the anabolic transcription factor, MYC. However, mechanistic details by which glucose activates Myc at the transcriptional level are poorly understood. METHODS Here, siRNA was used to test the role of ChREBP in the glucose response of MYC, ChIP and ChIPseq to identify potential regulatory binding sites, chromatin conformation capture to identify DNA/DNA interactions, and an adenovirus was constructed to expresses x-dCas9 and an sgRNA that specifically disrupts the recruitment of ChREBP to a specific targeted ChoRE. RESULTS We found that ChREBP is essential for glucose-mediated transcriptional induction of Myc, and for increases in Myc mRNA and protein abundance. Further, ChIPseq revealed that the carbohydrate response element (ChoRE) nearest to the Myc transcriptional start site (TSS) is immediately upstream of the gene encoding the lncRNA, Pvt1, 60,000 bp downstream of the Myc gene. Chromatin Conformation Capture (3C) confirmed a glucose-dependent interaction between these two sites. Transduction with an adenovirus expressing x-dCas9 and an sgRNA specifically targeting the highly conserved Pvt1 ChoRE, attenuates ChREBP recruitment, decreases Myc-Pvt1 DNA/DNA interaction, and decreases expression of the Pvt1 and Myc genes in response to glucose. Importantly, isolated and dispersed rat islet cells transduced with the ChoRE-disrupting adenovirus also display specific decreases in ChREBP-dependent, glucose-mediated expression of Pvt1 and Myc, as well as decreased glucose-stimulated β-cell proliferation. CONCLUSIONS The mitogenic glucose response of Myc is mediated via glucose-dependent recruitment of ChREBP to the promoter of the Pvt1 gene and subsequent DNA looping with the Myc promoter.
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Affiliation(s)
- Liora S Katz
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, NY 10029, USA
| | - Gabriel Brill
- Pharmacologic Sciences Department, Stony Brook University, Stony Brook, NY, USA(5)
| | - Peng Wang
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, NY 10029, USA
| | - Luca Lambertini
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, NY 10029, USA
| | - Pili Zhang
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, NY 10029, USA
| | | | - Hongtao Liu
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, NY 10029, USA
| | | | - Andrew F Stewart
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, NY 10029, USA
| | - Adolfo Garcia-Ocaña
- Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope, 1500 E Duarte Rd, Duarte, CA 91010, USA
| | - Donald K Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, NY 10029, USA.
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2
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Regulation of Normal and Neoplastic Proliferation and Metabolism by the Extended Myc Network. Cells 2022; 11:cells11243974. [PMID: 36552737 PMCID: PMC9777120 DOI: 10.3390/cells11243974] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 11/30/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022] Open
Abstract
The Myc Network, comprising a small assemblage of bHLH-ZIP transcription factors, regulates many hundreds to thousands of genes involved in proliferation, energy metabolism, translation and other activities. A structurally and functionally related set of factors known as the Mlx Network also supervises some of these same functions via the regulation of a more limited but overlapping transcriptional repertoire. Target gene co-regulation by these two Networks is the result of their sharing of three members that suppress target gene expression as well as by the ability of both Network's members to cross-bind one another's consensus DNA sites. The two Networks also differ in that the Mlx Network's control over transcription is positively regulated by several glycolytic pathway intermediates and other metabolites. These distinctive properties, functions and tissue expression patterns potentially allow for sensitive control of gene regulation in ways that are differentially responsive to environmental and metabolic cues while allowing for them to be both rapid and of limited duration. This review explores how such control might occur. It further discusses how the actual functional dependencies of the Myc and Mlx Networks rely upon cellular context and how they may differ between normal and neoplastic cells. Finally, consideration is given to how future studies may permit a more refined understanding of the functional interrelationships between the two Networks.
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Melnik BC, Schmitz G. Milk Exosomal microRNAs: Postnatal Promoters of β Cell Proliferation but Potential Inducers of β Cell De-Differentiation in Adult Life. Int J Mol Sci 2022; 23:ijms231911503. [PMID: 36232796 PMCID: PMC9569743 DOI: 10.3390/ijms231911503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/15/2022] [Accepted: 09/20/2022] [Indexed: 11/16/2022] Open
Abstract
Pancreatic β cell expansion and functional maturation during the birth-to-weaning period is driven by epigenetic programs primarily triggered by growth factors, hormones, and nutrients provided by human milk. As shown recently, exosomes derived from various origins interact with β cells. This review elucidates the potential role of milk-derived exosomes (MEX) and their microRNAs (miRs) on pancreatic β cell programming during the postnatal period of lactation as well as during continuous cow milk exposure of adult humans to bovine MEX. Mechanistic evidence suggests that MEX miRs stimulate mTORC1/c-MYC-dependent postnatal β cell proliferation and glycolysis, but attenuate β cell differentiation, mitochondrial function, and insulin synthesis and secretion. MEX miR content is negatively affected by maternal obesity, gestational diabetes, psychological stress, caesarean delivery, and is completely absent in infant formula. Weaning-related disappearance of MEX miRs may be the critical event switching β cells from proliferation to TGF-β/AMPK-mediated cell differentiation, whereas continued exposure of adult humans to bovine MEX miRs via intake of pasteurized cow milk may reverse β cell differentiation, promoting β cell de-differentiation. Whereas MEX miR signaling supports postnatal β cell proliferation (diabetes prevention), persistent bovine MEX exposure after the lactation period may de-differentiate β cells back to the postnatal phenotype (diabetes induction).
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Affiliation(s)
- Bodo C. Melnik
- Department of Dermatology, Environmental Medicine and Health Theory, University of Osnabrück, D-49076 Osnabrück, Germany
- Correspondence: ; Tel.: +49-52-4198-8060
| | - Gerd Schmitz
- Institute for Clinical Chemistry and Laboratory Medicine, University Hospital of Regensburg, University of Regensburg, D-93053 Regensburg, Germany
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4
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Katz LS, Brill G, Zhang P, Kumar A, Baumel-Alterzon S, Honig LB, Gómez-Banoy N, Karakose E, Tanase M, Doridot L, Alvarsson A, Davenport B, Wang P, Lambertini L, Stanley SA, Homann D, Stewart AF, Lo JC, Herman MA, Garcia-Ocaña A, Scott DK. Maladaptive positive feedback production of ChREBPβ underlies glucotoxic β-cell failure. Nat Commun 2022; 13:4423. [PMID: 35908073 PMCID: PMC9339008 DOI: 10.1038/s41467-022-32162-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 07/18/2022] [Indexed: 01/05/2023] Open
Abstract
Preservation and expansion of β-cell mass is a therapeutic goal for diabetes. Here we show that the hyperactive isoform of carbohydrate response-element binding protein (ChREBPβ) is a nuclear effector of hyperglycemic stress occurring in β-cells in response to prolonged glucose exposure, high-fat diet, and diabetes. We show that transient positive feedback induction of ChREBPβ is necessary for adaptive β-cell expansion in response to metabolic challenges. Conversely, chronic excessive β-cell-specific overexpression of ChREBPβ results in loss of β-cell identity, apoptosis, loss of β-cell mass, and diabetes. Furthermore, β-cell "glucolipotoxicity" can be prevented by deletion of ChREBPβ. Moreover, ChREBPβ-mediated cell death is mitigated by overexpression of the alternate CHREBP gene product, ChREBPα, or by activation of the antioxidant Nrf2 pathway in rodent and human β-cells. We conclude that ChREBPβ, whether adaptive or maladaptive, is an important determinant of β-cell fate and a potential target for the preservation of β-cell mass in diabetes.
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Affiliation(s)
- Liora S Katz
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Gabriel Brill
- Pharmacologic Sciences Department, Stony Brook University, Stony Brook, NY, USA
| | - Pili Zhang
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Anil Kumar
- Metabolic Phenotyping Core, University of Utah, 15N 2030 E, 585, Radiobiology building, Room 151, Salt Lake City, UT, 84112, USA
| | - Sharon Baumel-Alterzon
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Lee B Honig
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Nicolás Gómez-Banoy
- Weill Center for Metabolic Health and Division of Cardiology, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Esra Karakose
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Marius Tanase
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Ludivine Doridot
- Institut Cochin, Université de Paris, INSERM, CNRS, F-75014, Paris, France
| | - Alexandra Alvarsson
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
- Alpenglow Biosciences, Inc., 98103, Seattle, WA, USA
| | - Bennett Davenport
- 12800 East 19th Ave, Anschutz Medical Campus, Room P18-9403, University of Colorado, Aurora, CO, 80045, USA
| | - Peng Wang
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Luca Lambertini
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Sarah A Stanley
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Dirk Homann
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Andrew F Stewart
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - James C Lo
- Weill Center for Metabolic Health and Division of Cardiology, Department of Medicine, Weill Cornell Medicine, New York, NY, 10021, USA
| | - Mark A Herman
- Division of Endocrinology and Metabolism and Duke Molecular Physiology Institute, Duke University Medical Center, Durham, NC, USA
- Section of Diabetes, Endocrinology, and Metabolism, Baylor College of Medicine, One Baylor Plaza, MS: 185, R614, 77030, Houston, TX, USA
| | - Adolfo Garcia-Ocaña
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA
| | - Donald K Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1152, New York, 10029, USA.
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Zhang J, Zhang J, Fu Z, Zhang Y, Luo Z, Zhang P, Xu Y, Huang C. CHREBP suppresses gastric cancer progression via the cyclin D1-Rb-E2F1 pathway. Cell Death Dis 2022; 8:300. [PMID: 35768405 PMCID: PMC9243070 DOI: 10.1038/s41420-022-01079-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/30/2022] [Accepted: 06/01/2022] [Indexed: 12/03/2022]
Abstract
Accumulating evidence has demonstrated that carbohydrate response element binding protein (CHREBP) has a crucial function in tumor pathology. In this study, we found CHREBP downregulation in gastric cancer (GC) tissues, and CHREBP was determined to be an independent diagnostic marker of GC. The downregulation of CHREBP promoted cell proliferation and inhibited apoptosis. Moreover, the level of cyclin D1 was significantly correlated with CHREBP expression in GC and paracancerous normal samples. In addition, CHREBP transcriptionally inhibited cyclin D1 expression in GC cells. Tumor suppressor activity of CHREBP could be affected by the upregulation of cyclin D1. In summary, CHREBP was found to be an independent diagnostic marker of GC and to influence GC growth and apoptosis via targeting the cyclin D1-Rb-E2F1 pathway.
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Affiliation(s)
- Jianming Zhang
- Department of General Surgery, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, 100 Haining Road, Hongkou District, Shanghai, 200080, China
| | - Jing Zhang
- Department of Thoracic Surgery, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China.
| | - Zhongmao Fu
- Department of General Surgery, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, 100 Haining Road, Hongkou District, Shanghai, 200080, China
| | - Yuan Zhang
- Department of General Surgery, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, 100 Haining Road, Hongkou District, Shanghai, 200080, China
| | - Zai Luo
- Department of General Surgery, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, 100 Haining Road, Hongkou District, Shanghai, 200080, China
| | - Pengshan Zhang
- Department of General Surgery, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, 100 Haining Road, Hongkou District, Shanghai, 200080, China
| | - Yitian Xu
- Department of General Surgery, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, 100 Haining Road, Hongkou District, Shanghai, 200080, China
| | - Chen Huang
- Department of General Surgery, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, 100 Haining Road, Hongkou District, Shanghai, 200080, China.
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6
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Wang H, Lu J, Alencastro F, Roberts A, Fiedor J, Carroll P, Eisenman RN, Ranganathan S, Torbenson M, Duncan AW, Prochownik EV. Coordinated Cross-Talk Between the Myc and Mlx Networks in Liver Regeneration and Neoplasia. Cell Mol Gastroenterol Hepatol 2022; 13:1785-1804. [PMID: 35259493 PMCID: PMC9046243 DOI: 10.1016/j.jcmgh.2022.02.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 01/26/2023]
Abstract
BACKGROUND & AIMS The c-Myc (Myc) Basic helix-loop-helix leucine zipper (bHLH-ZIP) transcription factor is deregulated in most cancers. In association with Max, Myc controls target genes that supervise metabolism, ribosome biogenesis, translation, and proliferation. This Myc network crosstalks with the Mlx network, which consists of the Myc-like proteins MondoA and ChREBP, and Max-like Mlx. Together, this extended Myc network regulates both common and distinct gene targets. Here, we studied the consequence of Myc and/or Mlx ablation in the liver, particularly those pertaining to hepatocyte proliferation, metabolism, and spontaneous tumorigenesis. METHODS We examined the ability of hepatocytes lacking Mlx (MlxKO) or Myc+Mlx (double KO [DKO]) to repopulate the liver over an extended period of time in a murine model of type I tyrosinemia. We also compared this and other relevant behaviors, phenotypes, and transcriptomes of the livers with those from previously characterized MycKO, ChrebpKO, and MycKO × ChrebpKO mice. RESULTS Hepatocyte regenerative potential deteriorated as the Extended Myc Network was progressively dismantled. Genes and pathways dysregulated in MlxKO and DKO hepatocytes included those pertaining to translation, mitochondrial function, and hepatic steatosis resembling nonalcoholic fatty liver disease. The Myc and Mlx Networks were shown to crosstalk, with the latter playing a disproportionate role in target gene regulation. All cohorts also developed steatosis and molecular evidence of early steatohepatitis. Finally, MlxKO and DKO mice showed extensive hepatic adenomatosis. CONCLUSIONS In addition to showing cooperation between the Myc and Mlx Networks, this study showed the latter to be more important in maintaining proliferative, metabolic, and translational homeostasis, while concurrently serving as a suppressor of benign tumorigenesis. GEO accession numbers: GSE181371, GSE130178, and GSE114634.
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Affiliation(s)
- Huabo Wang
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Jie Lu
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Frances Alencastro
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; McGowan Institute for Regenerative Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Alexander Roberts
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Julia Fiedor
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Patrick Carroll
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Robert N Eisenman
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | | | - Michael Torbenson
- Department of Laboratory Medicine and Pathology, The Mayo Clinic, Rochester, Minnesota
| | - Andrew W Duncan
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; McGowan Institute for Regenerative Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Edward V Prochownik
- Division of Hematology/Oncology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania; Hillman Comprehensive Cancer Center, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; Department of Microbiology and Molecular Genetics, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
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7
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Rosselot C, Baumel-Alterzon S, Li Y, Brill G, Lambertini L, Katz LS, Lu G, Garcia-Ocaña A, Scott DK. The many lives of Myc in the pancreatic β-cell. J Biol Chem 2021; 296:100122. [PMID: 33239359 PMCID: PMC7949031 DOI: 10.1074/jbc.rev120.011149] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 11/20/2020] [Accepted: 11/25/2020] [Indexed: 12/19/2022] Open
Abstract
Diabetes results from insufficient numbers of functional pancreatic β-cells. Thus, increasing the number of available functional β-cells ex vivo for transplantation, or regenerating them in situ in diabetic patients, is a major focus of diabetes research. The transcription factor, Myc, discovered decades ago lies at the nexus of most, if not all, known proliferative pathways. Based on this, many studies in the 1990s and early 2000s explored the potential of harnessing Myc expression to expand β-cells for diabetes treatment. Nearly all these studies in β-cells used pathophysiological or supraphysiological levels of Myc and reported enhanced β-cell death, dedifferentiation, or the formation of insulinomas if cooverexpressed with Bcl-xL, an inhibitor of apoptosis. This obviously reduced the enthusiasm for Myc as a therapeutic target for β-cell regeneration. However, recent studies indicate that "gentle" induction of Myc expression enhances β-cell replication without induction of cell death or loss of insulin secretion, suggesting that appropriate levels of Myc could have therapeutic potential for β-cell regeneration. Furthermore, although it has been known for decades that Myc is induced by glucose in β-cells, very little is known about how this essential anabolic transcription factor perceives and responds to nutrients and increased insulin demand in vivo. Here we summarize the previous and recent knowledge of Myc in the β-cell, its potential for β-cell regeneration, and its physiological importance for neonatal and adaptive β-cell expansion.
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Affiliation(s)
- Carolina Rosselot
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Sharon Baumel-Alterzon
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Yansui Li
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Gabriel Brill
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Luca Lambertini
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Liora S Katz
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Geming Lu
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Adolfo Garcia-Ocaña
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA.
| | - Donald K Scott
- Diabetes Obesity Metabolism Institute, and the Mindich Child Health and Development Institute, The Icahn School of Medicine at Mount Sinai, New York, New York, USA
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Fan Q, Nørgaard RC, Grytten I, Ness CM, Lucas C, Vekterud K, Soedling H, Matthews J, Lemma RB, Gabrielsen OS, Bindesbøll C, Ulven SM, Nebb HI, Grønning-Wang LM, Sæther T. LXRα Regulates ChREBPα Transactivity in a Target Gene-Specific Manner through an Agonist-Modulated LBD-LID Interaction. Cells 2020; 9:cells9051214. [PMID: 32414201 PMCID: PMC7290792 DOI: 10.3390/cells9051214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 04/19/2020] [Accepted: 05/07/2020] [Indexed: 01/02/2023] Open
Abstract
The cholesterol-sensing nuclear receptor liver X receptor (LXR) and the glucose-sensing transcription factor carbohydrate responsive element-binding protein (ChREBP) are central players in regulating glucose and lipid metabolism in the liver. More knowledge of their mechanistic interplay is needed to understand their role in pathological conditions like fatty liver disease and insulin resistance. In the current study, LXR and ChREBP co-occupancy was examined by analyzing ChIP-seq datasets from mice livers. LXR and ChREBP interaction was determined by Co-immunoprecipitation (CoIP) and their transactivity was assessed by real-time quantitative polymerase chain reaction (qPCR) of target genes and gene reporter assays. Chromatin binding capacity was determined by ChIP-qPCR assays. Our data show that LXRα and ChREBPα interact physically and show a high co-occupancy at regulatory regions in the mouse genome. LXRα co-activates ChREBPα and regulates ChREBP-specific target genes in vitro and in vivo. This co-activation is dependent on functional recognition elements for ChREBP but not for LXR, indicating that ChREBPα recruits LXRα to chromatin in trans. The two factors interact via their key activation domains; the low glucose inhibitory domain (LID) of ChREBPα and the ligand-binding domain (LBD) of LXRα. While unliganded LXRα co-activates ChREBPα, ligand-bound LXRα surprisingly represses ChREBPα activity on ChREBP-specific target genes. Mechanistically, this is due to a destabilized LXRα:ChREBPα interaction, leading to reduced ChREBP-binding to chromatin and restricted activation of glycolytic and lipogenic target genes. This ligand-driven molecular switch highlights an unappreciated role of LXRα in responding to nutritional cues that was overlooked due to LXR lipogenesis-promoting function.
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Affiliation(s)
- Qiong Fan
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (Q.F.); (K.V.); (C.B.)
| | - Rikke Christine Nørgaard
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (R.C.N.); (C.M.N.); (C.L.); (H.S.); (J.M.); (S.M.U.); (H.I.N.); (L.M.G.-W.)
| | - Ivar Grytten
- Department of Informatics, Faculty of Mathematics and Natural Sciences, University of Oslo, N-0317 Oslo, Norway;
| | - Cecilie Maria Ness
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (R.C.N.); (C.M.N.); (C.L.); (H.S.); (J.M.); (S.M.U.); (H.I.N.); (L.M.G.-W.)
| | - Christin Lucas
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (R.C.N.); (C.M.N.); (C.L.); (H.S.); (J.M.); (S.M.U.); (H.I.N.); (L.M.G.-W.)
| | - Kristin Vekterud
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (Q.F.); (K.V.); (C.B.)
| | - Helen Soedling
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (R.C.N.); (C.M.N.); (C.L.); (H.S.); (J.M.); (S.M.U.); (H.I.N.); (L.M.G.-W.)
| | - Jason Matthews
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (R.C.N.); (C.M.N.); (C.L.); (H.S.); (J.M.); (S.M.U.); (H.I.N.); (L.M.G.-W.)
| | - Roza Berhanu Lemma
- Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, N-0317 Oslo, Norway; (R.B.L.); (O.S.G.)
| | - Odd Stokke Gabrielsen
- Department of Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, N-0317 Oslo, Norway; (R.B.L.); (O.S.G.)
| | - Christian Bindesbøll
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (Q.F.); (K.V.); (C.B.)
| | - Stine Marie Ulven
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (R.C.N.); (C.M.N.); (C.L.); (H.S.); (J.M.); (S.M.U.); (H.I.N.); (L.M.G.-W.)
| | - Hilde Irene Nebb
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (R.C.N.); (C.M.N.); (C.L.); (H.S.); (J.M.); (S.M.U.); (H.I.N.); (L.M.G.-W.)
| | - Line Mariann Grønning-Wang
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (R.C.N.); (C.M.N.); (C.L.); (H.S.); (J.M.); (S.M.U.); (H.I.N.); (L.M.G.-W.)
| | - Thomas Sæther
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway; (Q.F.); (K.V.); (C.B.)
- Correspondence: ; Tel.: +47-22-851510
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9
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Gouw AM, Margulis K, Liu NS, Raman SJ, Mancuso A, Toal GG, Tong L, Mosley A, Hsieh AL, Sullivan DK, Stine ZE, Altman BJ, Schulze A, Dang CV, Zare RN, Felsher DW. The MYC Oncogene Cooperates with Sterol-Regulated Element-Binding Protein to Regulate Lipogenesis Essential for Neoplastic Growth. Cell Metab 2019; 30:556-572.e5. [PMID: 31447321 PMCID: PMC6911354 DOI: 10.1016/j.cmet.2019.07.012] [Citation(s) in RCA: 113] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 09/24/2018] [Accepted: 07/24/2019] [Indexed: 12/14/2022]
Abstract
Lipid metabolism is frequently perturbed in cancers, but the underlying mechanism is unclear. We present comprehensive evidence that oncogene MYC, in collaboration with transcription factor sterol-regulated element-binding protein (SREBP1), regulates lipogenesis to promote tumorigenesis. We used human and mouse tumor-derived cell lines, tumor xenografts, and four conditional transgenic mouse models of MYC-induced tumors to show that MYC regulates lipogenesis genes, enzymes, and metabolites. We found that MYC induces SREBP1, and they collaborate to activate fatty acid (FA) synthesis and drive FA chain elongation from glucose and glutamine. Further, by employing desorption electrospray ionization mass spectrometry imaging (DESI-MSI), we observed in vivo lipidomic changes upon MYC induction across different cancers, for example, a global increase in glycerophosphoglycerols. After inhibition of FA synthesis, tumorigenesis was blocked, and tumors regressed in both xenograft and primary transgenic mouse models, revealing the vulnerability of MYC-induced tumors to the inhibition of lipogenesis.
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Affiliation(s)
- Arvin M Gouw
- Division of Oncology, Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | - Natalie S Liu
- Division of Oncology, Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Sudha J Raman
- Department of Biochemistry and Molecular Biology, Wurzburg University, Wurzburg, Germany
| | - Anthony Mancuso
- Department of Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Georgia G Toal
- Division of Oncology, Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Ling Tong
- Division of Oncology, Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Adriane Mosley
- Division of Oncology, Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Annie L Hsieh
- Department of Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Delaney K Sullivan
- Division of Oncology, Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zachary E Stine
- Department of Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Brian J Altman
- Department of Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Almut Schulze
- Department of Biochemistry and Molecular Biology, Wurzburg University, Wurzburg, Germany
| | - Chi V Dang
- Department of Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Ludwig Institute for Cancer Research, New York, NY 10017, USA; The Wistar Institute, Philadelphia, PA 19104, USA.
| | - Richard N Zare
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA; Ludwig Institute for Cancer Research, New York, NY 10017, USA.
| | - Dean W Felsher
- Division of Oncology, Departments of Medicine and Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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10
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Li Y, Yang D, Tian N, Zhang P, Zhu Y, Meng J, Feng M, Lu Y, Liu Q, Tong L, Hu L, Zhang L, Yang JY, Wu L, Tong X. The ubiquitination ligase SMURF2 reduces aerobic glycolysis and colorectal cancer cell proliferation by promoting ChREBP ubiquitination and degradation. J Biol Chem 2019; 294:14745-14756. [PMID: 31409643 DOI: 10.1074/jbc.ra119.007508] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 08/07/2019] [Indexed: 12/31/2022] Open
Abstract
The glucose-responsive transcription factor carbohydrate response element-binding protein (ChREBP) critically promotes aerobic glycolysis and cell proliferation in colorectal cancer cells. It has been reported that ubiquitination may be important in the regulation of ChREBP protein levels and activities. However, the ChREBP-specific E3 ligase and molecular mechanism of ChREBP ubiquitination remains unclear. Using database exploration and expression analysis, we found here that levels of the E3 ligase SMURF2 (Smad-ubiquitination regulatory factor 2) negatively correlate with those of ChREBP in cancer tissues and cell lines. We observed that SMURF2 interacts with ChREBP and promotes ChREBP ubiquitination and degradation via the proteasome pathway. Interestingly, ectopic SMURF2 expression not only decreased ChREBP levels but also reduced aerobic glycolysis, increased oxygen consumption, and decreased cell proliferation in colorectal cancer cells. Moreover, SMURF2 knockdown increased aerobic glycolysis, decreased oxygen consumption, and enhanced cell proliferation in these cells, mostly because of increased ChREBP accumulation. Furthermore, we identified Ser/Thr kinase AKT as an upstream suppressor of SMURF2 that protects ChREBP from ubiquitin-mediated degradation. Taken together, our results indicate that SMURF2 reduces aerobic glycolysis and cell proliferation by promoting ChREBP ubiquitination and degradation via the proteasome pathway in colorectal cancer cells. We conclude that the SMURF2-ChREBP interaction might represent a potential target for managing colorectal cancer.
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Affiliation(s)
- Yakui Li
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Dianqiang Yang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Na Tian
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ping Zhang
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yemin Zhu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jian Meng
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ming Feng
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Ying Lu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Qi Liu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Lingfeng Tong
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Lei Hu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Lukuan Zhang
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - James Y Yang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.,Ministry of Education Engineering Research Center of Molecular Diagnostics and State-Province Joint Engineering Laboratory of Targeted Drugs from Natural Products, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Lifang Wu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xuemei Tong
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of National Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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11
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Jois T, Chen W, Howard V, Harvey R, Youngs K, Thalmann C, Saha P, Chan L, Cowley MA, Sleeman MW. Deletion of hepatic carbohydrate response element binding protein (ChREBP) impairs glucose homeostasis and hepatic insulin sensitivity in mice. Mol Metab 2017; 6:1381-1394. [PMID: 29107286 PMCID: PMC5681238 DOI: 10.1016/j.molmet.2017.07.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 07/11/2017] [Accepted: 07/12/2017] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVE Carbohydrate response element binding protein (ChREBP) is a transcription factor that responds to glucose and activates genes involved in the glycolytic and lipogenic pathways. Recent studies have linked adipose ChREBP to insulin sensitivity in mice. However, while ChREBP is most highly expressed in the liver, the effect of hepatic ChREBP on insulin sensitivity remains unknown. To clarify the importance of hepatic ChREBP on glucose homeostasis, we have generated a knockout mouse model that lacks this protein specifically in the liver (Liver-ChREBP KO). METHODS Using Liver-ChREBP KO mice, we investigated whether hepatic ChREBP deletion influences insulin sensitivity, glucose homeostasis and the development of hepatic steatosis utilizing various dietary stressors. Furthermore, we determined gene expression changes in response to fasted and fed states in liver, white, and brown adipose tissues. RESULTS Liver-ChREBP KO mice had impaired insulin sensitivity as indicated by reduced glucose infusion to maintain euglycemia during hyperinsulinemic-euglycemic clamps on both chow (25% lower) and high-fat diet (33% lower) (p < 0.05). This corresponded with attenuated suppression of hepatic glucose production. Although Liver-ChREBP KO mice were protected against carbohydrate-induced hepatic steatosis, they displayed worsened glucose tolerance. Liver-ChREBP KO mice did not show the expected gene expression changes in liver in response to fasted and fed states. Interestingly, hepatic ChREBP deletion also resulted in gene expression changes in white and brown adipose tissues, suggesting inter-tissue communication. This included an almost complete abolition of BAT ChREBPβ induction in the fed state (0.15-fold) (p = 0.015) along with reduced lipogenic genes. In contrast, WAT showed inappropriate increases in lipogenic genes in the fasted state along with increased PEPCK1 in both fasted (3.4-fold) and fed (5.1-fold) states (p < 0.0001). CONCLUSIONS Overall, hepatic ChREBP is protective in regards to hepatic insulin sensitivity and whole body glucose homeostasis. Hepatic ChREBP action can influence other peripheral tissues and is likely essential in coordinating the body's response to different feeding states.
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Affiliation(s)
- Tara Jois
- Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Weiyi Chen
- Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Victor Howard
- Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Rebecca Harvey
- Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Kristina Youngs
- Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Claudia Thalmann
- Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Pradip Saha
- Diabetes and Endocrinology Research Center, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Lawrence Chan
- Diabetes and Endocrinology Research Center, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Michael A Cowley
- Department of Physiology, Monash University, Clayton, Victoria, Australia; Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
| | - Mark W Sleeman
- Department of Physiology, Monash University, Clayton, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
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12
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Abdul-Wahed A, Guilmeau S, Postic C. Sweet Sixteenth for ChREBP: Established Roles and Future Goals. Cell Metab 2017; 26:324-341. [PMID: 28768172 DOI: 10.1016/j.cmet.2017.07.004] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 06/01/2017] [Accepted: 07/12/2017] [Indexed: 12/25/2022]
Abstract
With the identification of ChREBP in 2001, our interest in understanding the molecular control of carbohydrate sensing has surged. While ChREBP was initially studied as a master regulator of lipogenesis in liver and fat tissue, it is now clear that ChREBP functions as a central metabolic coordinator in a variety of cell types in response to environmental and hormonal signals, with wide implications in health and disease. Celebrating its sweet sixteenth birthday, we review here the current knowledge about the function and regulation of ChREBP throughout usual and less explored tissues, to recapitulate ChREBP's role as a whole-body glucose sensor.
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Affiliation(s)
- Aya Abdul-Wahed
- Inserm, U1016, Institut Cochin, 75014 Paris, France; CNRS UMR 8104, 75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Sandra Guilmeau
- Inserm, U1016, Institut Cochin, 75014 Paris, France; CNRS UMR 8104, 75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
| | - Catherine Postic
- Inserm, U1016, Institut Cochin, 75014 Paris, France; CNRS UMR 8104, 75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France.
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13
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Functional Analysis of Mouse G6pc1 Mutations Using a Novel In Situ Assay for Glucose-6-Phosphatase Activity and the Effect of Mutations in Conserved Human G6PC1/G6PC2 Amino Acids on G6PC2 Protein Expression. PLoS One 2016; 11:e0162439. [PMID: 27611587 PMCID: PMC5017610 DOI: 10.1371/journal.pone.0162439] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 08/23/2016] [Indexed: 11/19/2022] Open
Abstract
Elevated fasting blood glucose (FBG) has been associated with increased risk for development of type 2 diabetes. Single nucleotide polymorphisms (SNPs) in G6PC2 are the most important common determinants of variations in FBG in humans. Studies using G6pc2 knockout mice suggest that G6pc2 regulates the glucose sensitivity of insulin secretion. G6PC2 and the related G6PC1 and G6PC3 genes encode glucose-6-phosphatase catalytic subunits. This study describes a functional analysis of 22 non-synonymous G6PC2 SNPs, that alter amino acids that are conserved in human G6PC1, mouse G6pc1 and mouse G6pc2, with the goal of identifying variants that potentially affect G6PC2 activity/expression. Published data suggest strong conservation of catalytically important amino acids between all four proteins and the related G6PC3 isoform. Because human G6PC2 has very low glucose-6-phosphatase activity we used an indirect approach, examining the effect of these SNPs on mouse G6pc1 activity. Using a novel in situ functional assay for glucose-6-phosphatase activity we demonstrate that the amino acid changes associated with the human G6PC2 rs144254880 (Arg79Gln), rs149663725 (Gly114Arg) and rs2232326 (Ser324Pro) SNPs reduce mouse G6pc1 enzyme activity without affecting protein expression. The Arg79Gln variant alters an amino acid mutation of which, in G6PC1, has previously been shown to cause glycogen storage disease type 1a. We also demonstrate that the rs368382511 (Gly8Glu), rs138726309 (His177Tyr), rs2232323 (Tyr207Ser) rs374055555 (Arg293Trp), rs2232326 (Ser324Pro), rs137857125 (Pro313Leu) and rs2232327 (Pro340Leu) SNPs confer decreased G6PC2 protein expression. In summary, these studies identify multiple G6PC2 variants that have the potential to be associated with altered FBG in humans.
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14
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Identification of HNF-4α as a key transcription factor to promote ChREBP expression in response to glucose. Sci Rep 2016; 6:23944. [PMID: 27029511 PMCID: PMC4814918 DOI: 10.1038/srep23944] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 03/16/2016] [Indexed: 01/08/2023] Open
Abstract
Transcription factor carbohydrate responsive element binding protein (ChREBP) promotes glycolysis and lipogenesis in metabolic tissues and cancer cells. ChREBP-α and ChREBP-β, two isoforms of ChREBP transcribed from different promoters, are both transcriptionally induced by glucose. However, the mechanism by which glucose increases ChREBP mRNA levels remains unclear. Here we report that hepatocyte nuclear factor 4 alpha (HNF-4α) is a key transcription factor for glucose-induced ChREBP-α and ChREBP-β expression. Ectopic HNF-4α expression increased ChREBP transcription while knockdown of HNF-4α greatly reduced ChREBP mRNA levels in liver cancer cells and mouse primary hepatocytes. HNF-4α not only directly bound to an E-box-containing region in intron 12 of the ChREBP gene, but also promoted ChREBP-β transcription by directly binding to two DR1 sites and one E-box-containing site of the ChREBP-β promoter. Moreover, HNF-4α interacted with ChREBP-α and synergistically promoted ChREBP-β transcription. Functionally, HNF-4α suppression reduced glucose-dependent ChREBP induction. Increased nuclear abundance of HNF-4α and its binding to cis-elements of ChREBP gene in response to glucose contributed to glucose-responsive ChREBP transcription. Taken together, our results not only revealed the novel mechanism by which HNF-4α promoted ChREBP transcription in response to glucose, but also demonstrated that ChREBP-α and HNF-4α synergistically increased ChREBP-β transcription.
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15
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Zhang P, Kumar A, Katz LS, Li L, Paulynice M, Herman MA, Scott DK. Induction of the ChREBPβ Isoform Is Essential for Glucose-Stimulated β-Cell Proliferation. Diabetes 2015; 64:4158-70. [PMID: 26384380 PMCID: PMC4657577 DOI: 10.2337/db15-0239] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 09/05/2015] [Indexed: 12/17/2022]
Abstract
Carbohydrate-responsive element-binding protein (ChREBP) is a glucose-sensing transcription factor required for glucose-stimulated proliferation of pancreatic β-cells in rodents and humans. The full-length isoform (ChREBPα) has a low glucose inhibitory domain (LID) that restrains the transactivation domain when glucose catabolism is minimal. A novel isoform of ChREBP (ChREBPβ) was recently described that lacks the LID domain and is therefore constitutively and more potently active. ChREBPβ has not been described in β-cells nor has its role in glucose-stimulated proliferation been determined. We found that ChREBPβ is highly expressed in response to glucose, particularly with prolonged culture in hyperglycemic conditions. In addition, small interfering RNAs that knocked down ChREBPβ transcripts without affecting ChREBPα expression or activity decreased glucose-stimulated expression of carbohydrate response element-containing genes and glucose-stimulated proliferation in INS-1 cells and in isolated rat islets. Quantitative chromatin immunoprecipitation, electrophoretic mobility shift assays, and luciferase reporter assays were used to demonstrate that ChREBP binds to a newly identified powerful carbohydrate response element in β-cells and hepatocytes, distinct from that in differentiated 3T3-L1 adipocytes. We conclude that ChREBPβ contributes to glucose-stimulated gene expression and proliferation in β-cells, with recruitment of ChREBPα to tissue-specific elements of the ChREBPβ isoform promoter.
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Affiliation(s)
- Pili Zhang
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Anil Kumar
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Liora S Katz
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Lucy Li
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Martine Paulynice
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | | | - Donald K Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
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16
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Diolaiti D, McFerrin L, Carroll PA, Eisenman RN. Functional interactions among members of the MAX and MLX transcriptional network during oncogenesis. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1849:484-500. [PMID: 24857747 PMCID: PMC4241192 DOI: 10.1016/j.bbagrm.2014.05.016] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Revised: 04/23/2014] [Accepted: 05/14/2014] [Indexed: 01/27/2023]
Abstract
The transcription factor MYC and its related family members MYCN and MYCL have been implicated in the etiology of a wide spectrum of human cancers. Compared to other oncoproteins, such as RAS or SRC, MYC is unique because its protein coding region is rarely mutated. Instead, MYC's oncogenic properties are unleashed by regulatory mutations leading to unconstrained high levels of expression. Under both normal and pathological conditions MYC regulates multiple aspects of cellular physiology including proliferation, differentiation, apoptosis, growth and metabolism by controlling the expression of thousands of genes. How a single transcription factor exerts such broad effects remains a fascinating puzzle. Notably, MYC is part of a network of bHLHLZ proteins centered on the MYC heterodimeric partner MAX and its counterpart, the MAX-like protein MLX. This network includes MXD1-4, MNT, MGA, MONDOA and MONDOB proteins. With some exceptions, MXD proteins have been functionally linked to cell cycle arrest and differentiation, while MONDO proteins control cellular metabolism. Although the temporal expression patterns of many of these proteins can differ markedly they are frequently expressed simultaneously in the same cellular context, and potentially bind to the same, or similar DNA consensus sequence. Here we review the activities and interactions among these proteins and propose that the broad spectrum of phenotypes elicited by MYC deregulation is intimately connected to the functions and regulation of the other network members. Furthermore, we provide a meta-analysis of TCGA data suggesting that the coordinate regulation of the network is important in MYC driven tumorigenesis. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.
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Affiliation(s)
- Daniel Diolaiti
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, USA
| | - Lisa McFerrin
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, USA
| | - Patrick A Carroll
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, USA
| | - Robert N Eisenman
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, USA.
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17
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Chen H, Wu L, Li Y, Meng J, Lin N, Yang D, Zhu Y, Li X, Li M, Xu Y, Wu Y, Tong X, Su Q. Advanced glycation end products increase carbohydrate responsive element binding protein expression and promote cancer cell proliferation. Mol Cell Endocrinol 2014; 395:69-78. [PMID: 25111846 DOI: 10.1016/j.mce.2014.07.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 07/25/2014] [Accepted: 07/29/2014] [Indexed: 01/12/2023]
Abstract
Diabetic patients have increased levels of advanced glycation end products (AGEs) and the role of AGEs in regulating cancer cell proliferation is unclear. Here, we found that treating colorectal and liver cancer cells with AGEs promoted cell proliferation. AGEs stimulated both the expression and activation of a key transcription factor called carbohydrate responsive element binding protein (ChREBP) which had been shown to promote glycolytic and anabolic activity as well as proliferation of colorectal and liver cancer cells. Using siRNAs or the antagonistic antibody for the receptor for advanced glycation end-products (RAGE) blocked AGEs-induced ChREBP expression or cell proliferation in cancer cells. Suppressing ChREBP expression severely impaired AGEs-induced cancer cell proliferation. Taken together, these results demonstrate that AGEs-RAGE signaling enhances cancer cell proliferation in which AGEs-mediated ChREBP induction plays an important role. These findings may provide new explanation for increased cancer progression in diabetic patients.
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Affiliation(s)
- Hanbei Chen
- Department of Endocrinology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, 1665, Kong Jiang Road, Shanghai, 200092, China
| | - Lifang Wu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, 280 S. Chongqing Road, Shanghai, 200025, China
| | - Yakui Li
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, 280 S. Chongqing Road, Shanghai, 200025, China
| | - Jian Meng
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, 280 S. Chongqing Road, Shanghai, 200025, China
| | - Ning Lin
- Department of Endocrinology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, 1665, Kong Jiang Road, Shanghai, 200092, China
| | - Dianqiang Yang
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, 280 S. Chongqing Road, Shanghai, 200025, China; Department of Physiology, Dalian Medical University, 9 Xiduan, Lvshun South Road, Dalian, Liaoning Province, 116044, China
| | - Yemin Zhu
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, 280 S. Chongqing Road, Shanghai, 200025, China
| | - Xiaoyong Li
- Department of Endocrinology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, 1665, Kong Jiang Road, Shanghai, 200092, China
| | - Minle Li
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, 280 S. Chongqing Road, Shanghai, 200025, China
| | - Ye Xu
- Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, 270 Dongan Road, Shanghai, 200032, China
| | - Yuchen Wu
- Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, 270 Dongan Road, Shanghai, 200032, China
| | - Xuemei Tong
- Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, 280 S. Chongqing Road, Shanghai, 200025, China.
| | - Qing Su
- Department of Endocrinology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, 1665, Kong Jiang Road, Shanghai, 200092, China.
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18
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Flightless I homolog negatively regulates ChREBP activity in cancer cells. Int J Biochem Cell Biol 2013; 45:2688-97. [PMID: 24055811 DOI: 10.1016/j.biocel.2013.09.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 09/02/2013] [Accepted: 09/10/2013] [Indexed: 11/21/2022]
Abstract
The glucose-responsive transcription factor carbohydrate responsive element binding protein (ChREBP) plays an important role in regulating glucose metabolism in support of anabolic synthesis in both hepatocytes and cancer cells. In order to further investigate the molecular mechanism by which ChREBP regulates transcription, we used a proteomic approach to identify proteins interacting with ChREBP. We found several potential ChREBP-interacting partners, one of which, flightless I homolog (FLII) was verified to interact and co-localize with ChREBP in HCT116 colorectal cancer and HepG2 hepatocellular carcinoma cells. FLII is a member of the gelsolin superfamily of actin-remodeling proteins and can function as a transcriptional co-regulator. The C-terminal 227 amino acid region of ChREBP containing the DNA-binding domain interacted with FLII. Both the N-terminal leucine-rich repeat (LRR) domain and C-terminal gelsolin homolog domain (GLD) of FLII interacted and co-localized with ChREBP. ChREBP and FLII localized in both the cytoplasm and nucleus of cancer cells. Glucose increased expression and nuclear localization of ChREBP, and had minimal effect on the level and distribution of FLII. FLII knockdown using siRNAs increased mRNA and protein levels of ChREBP-activated genes and decreased transcription of ChREBP-repressed genes in cancer cells. Conversely, FLII overexpression negatively regulated ChREBP-mediated transcription in cancer cells. Our findings suggest that FLII is a component of the ChREBP transcriptional complex and negatively regulates ChREBP function in cancer cells.
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Filhoulaud G, Guilmeau S, Dentin R, Girard J, Postic C. Novel insights into ChREBP regulation and function. Trends Endocrinol Metab 2013; 24:257-68. [PMID: 23597489 DOI: 10.1016/j.tem.2013.01.003] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 12/23/2012] [Accepted: 01/03/2013] [Indexed: 12/17/2022]
Abstract
Glucose is an energy source that also controls the expression of key genes involved in energetic metabolism through the glucose-signaling transcription factor carbohydrate response element-binding protein (ChREBP). ChREBP has recently emerged as a central regulator of glycolysis and de novo fatty acid synthesis in liver, but new evidence shows that it plays a broader and crucial role in various processes, ranging from glucolipotoxicity to apoptosis and/or proliferation in specific cell types. However, several aspects of ChREBP activation by glucose metabolites are currently controversial, as well as the effects of activating or inhibiting ChREBP, on insulin sensitivity, which might depend on genetic, dietary or environmental factors. Thus, much remains to be elucidated. Here, we summarize our current understanding of the regulation and function of this fascinating transcription factor.
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20
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Metukuri MR, Zhang P, Basantani MK, Chin C, Stamateris RE, Alonso LC, Takane KK, Gramignoli R, Strom SC, O’Doherty RM, Stewart AF, Vasavada RC, Garcia-Ocaña A, Scott DK. ChREBP mediates glucose-stimulated pancreatic β-cell proliferation. Diabetes 2012; 61:2004-15. [PMID: 22586588 PMCID: PMC3402328 DOI: 10.2337/db11-0802] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Glucose stimulates rodent and human β-cell replication, but the intracellular signaling mechanisms are poorly understood. Carbohydrate response element-binding protein (ChREBP) is a lipogenic glucose-sensing transcription factor with unknown functions in pancreatic β-cells. We tested the hypothesis that ChREBP is required for glucose-stimulated β-cell proliferation. The relative expression of ChREBP was determined in liver and β-cells using quantitative RT-PCR (qRT-PCR), immunoblotting, and immunohistochemistry. Loss- and gain-of-function studies were performed using small interfering RNA and genetic deletion of ChREBP and adenoviral overexpression of ChREBP in rodent and human β-cells. Proliferation was measured by 5-bromo-2'-deoxyuridine incorporation, [(3)H]thymidine incorporation, and fluorescence-activated cell sorter analysis. In addition, the expression of cell cycle regulatory genes was measured by qRT-PCR and immunoblotting. ChREBP expression was comparable with liver in mouse pancreata and in rat and human islets. Depletion of ChREBP decreased glucose-stimulated proliferation in β-cells isolated from ChREBP(-/-) mice, in INS-1-derived 832/13 cells, and in primary rat and human β-cells. Furthermore, depletion of ChREBP decreased the glucose-stimulated expression of cell cycle accelerators. Overexpression of ChREBP amplified glucose-stimulated proliferation in rat and human β-cells, with concomitant increases in cyclin gene expression. In conclusion, ChREBP mediates glucose-stimulated proliferation in pancreatic β-cells.
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Affiliation(s)
- Mallikarjuna R. Metukuri
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Pili Zhang
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Mahesh K. Basantani
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Connie Chin
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Rachel E. Stamateris
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Laura C. Alonso
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Karen K. Takane
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Roberto Gramignoli
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Stephen C. Strom
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Robert M. O’Doherty
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Andrew F. Stewart
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Rupangi C. Vasavada
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Adolfo Garcia-Ocaña
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Donald K. Scott
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, Pennsylvania
- Corresponding author: Donald K. Scott,
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21
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Havula E, Hietakangas V. Glucose sensing by ChREBP/MondoA-Mlx transcription factors. Semin Cell Dev Biol 2012; 23:640-7. [PMID: 22406740 DOI: 10.1016/j.semcdb.2012.02.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 02/24/2012] [Indexed: 01/02/2023]
Abstract
The paralogous transcription factors ChREBP and MondoA, together with their common binding partner Mlx, have emerged as key mediators of intracellular glucose sensing. By regulating target genes involved in glycolysis and lipogenesis, they mediate metabolic adaptation to changing glucose levels. As disturbed glucose homeostasis plays a central role in human metabolic diseases and as cancer cells often display altered glucose metabolism, better understanding of cellular glucose sensing will likely uncover new therapeutic opportunities. Here we review the regulation, function and evolutionary conservation of the ChREBP/MondoA-Mlx glucose sensing system and discuss possible directions for future research.
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Affiliation(s)
- Essi Havula
- Institute of Biotechnology, University of Helsinki, Viikinkaari 1, 00014 Helsinki, Finland
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22
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Bensellam M, Duvillié B, Rybachuk G, Laybutt DR, Magnan C, Guiot Y, Pouysségur J, Jonas JC. Glucose-induced O₂ consumption activates hypoxia inducible factors 1 and 2 in rat insulin-secreting pancreatic beta-cells. PLoS One 2012; 7:e29807. [PMID: 22235342 PMCID: PMC3250482 DOI: 10.1371/journal.pone.0029807] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 12/06/2011] [Indexed: 12/21/2022] Open
Abstract
Background Glucose increases the expression of glycolytic enzymes and other hypoxia-response genes in pancreatic beta-cells. Here, we tested whether this effect results from the activation of Hypoxia-Inducible-factors (HIF) 1 and 2 in a hypoxia-dependent manner. Methodology/Principal Findings Isolated rat islets and insulin-secreting INS-1E cells were stimulated with nutrients at various pO2 values or treated with the HIF activator CoCl2. HIF-target gene mRNA levels and HIF subunit protein levels were measured by real-time RT-PCR, Western Blot and immunohistochemistry. The formation of pimonidazole-protein adducts was used as an indicator of hypoxia. In INS-1E and islet beta-cells, glucose concentration-dependently stimulated formation of pimonidazole-protein adducts, HIF1 and HIF2 nuclear expression and HIF-target gene mRNA levels to a lesser extent than CoCl2 or a four-fold reduction in pO2. Islets also showed signs of HIF activation in diabetic Leprdb/db but not non-diabetic Leprdb/+ mice. In vitro, these glucose effects were reproduced by nutrient secretagogues that bypass glycolysis, and were inhibited by a three-fold increase in pO2 or by inhibitors of Ca2+ influx and insulin secretion. In INS-1E cells, small interfering RNA-mediated knockdown of Hif1α and Hif2α, alone or in combination, indicated that the stimulation of glycolytic enzyme mRNA levels depended on both HIF isoforms while the vasodilating peptide adrenomedullin was a HIF2-specific target gene. Conclusions/Significance Glucose-induced O2 consumption creates an intracellular hypoxia that activates HIF1 and HIF2 in rat beta-cells, and this glucose effect contributes, together with the activation of other transcription factors, to the glucose stimulation of expression of some glycolytic enzymes and other hypoxia response genes.
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Affiliation(s)
- Mohammed Bensellam
- Pôle d′Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - Bertrand Duvillié
- INSERM U845, Faculté de Médecine, Research Center Growth and Signalling, Université Paris Descartes, Hôpital Necker, Paris, France
| | - Galyna Rybachuk
- Pôle d′Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - D. Ross Laybutt
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, Australia
| | - Christophe Magnan
- Unité de Biologie Fonctionnelle et Adaptative, CNRS-Université Paris Diderot-Paris 7, Paris, France
| | - Yves Guiot
- Pôle de Morphologie, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - Jacques Pouysségur
- Institute of Developmental Biology and Cancer Research, University of Nice, CNRS UMR 6543, Centre A. Lacassagne, Nice, France
| | - Jean-Christophe Jonas
- Pôle d′Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
- * E-mail:
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23
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Shaked M, Ketzinel-Gilad M, Cerasi E, Kaiser N, Leibowitz G. AMP-activated protein kinase (AMPK) mediates nutrient regulation of thioredoxin-interacting protein (TXNIP) in pancreatic beta-cells. PLoS One 2011; 6:e28804. [PMID: 22194917 PMCID: PMC3237554 DOI: 10.1371/journal.pone.0028804] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 11/15/2011] [Indexed: 02/07/2023] Open
Abstract
Thioredoxin-interacting protein (TXNIP) regulates critical biological processes including inflammation, stress and apoptosis. TXNIP is upregulated by glucose and is a critical mediator of hyperglycemia-induced beta-cell apoptosis in diabetes. In contrast, the saturated long-chain fatty acid palmitate, although toxic to the beta-cell, inhibits TXNIP expression. The mechanisms involved in the opposing effects of glucose and fatty acids on TXNIP expression are unknown. We found that both palmitate and oleate inhibited TXNIP in a rat beta-cell line and islets. Palmitate inhibition of TXNIP was independent of fatty acid beta-oxidation or esterification. AMP-activated protein kinase (AMPK) has an important role in cellular energy sensing and control of metabolic homeostasis; therefore we investigated its involvement in nutrient regulation of TXNIP. As expected, glucose inhibited whereas palmitate stimulated AMPK. Pharmacologic activators of AMPK mimicked fatty acids by inhibiting TXNIP. AMPK knockdown increased TXNIP expression in presence of high glucose with and without palmitate, indicating that nutrient (glucose and fatty acids) effects on TXNIP are mediated in part via modulation of AMPK activity. TXNIP is transcriptionally regulated by carbohydrate response element-binding protein (ChREBP). Palmitate inhibited glucose-stimulated ChREBP nuclear entry and recruitment to the Txnip promoter, thereby inhibiting Txnip transcription. We conclude that AMPK is an important regulator of Txnip transcription via modulation of ChREBP activity. The divergent effects of glucose and fatty acids on TXNIP expression result in part from their opposing effects on AMPK activity. In light of the important role of TXNIP in beta-cell apoptosis, its inhibition by fatty acids can be regarded as an adaptive/protective response to glucolipotoxicity. The finding that AMPK mediates nutrient regulation of TXNIP may have important implications for the pathophysiology and treatment of diabetes.
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Affiliation(s)
- Maayan Shaked
- Endocrinology and Metabolism Service, Department of Medicine, Hadassah - Hebrew University Medical Center, Jerusalem, Israel
| | - Mali Ketzinel-Gilad
- Endocrinology and Metabolism Service, Department of Medicine, Hadassah - Hebrew University Medical Center, Jerusalem, Israel
| | - Erol Cerasi
- Endocrinology and Metabolism Service, Department of Medicine, Hadassah - Hebrew University Medical Center, Jerusalem, Israel
| | - Nurit Kaiser
- Endocrinology and Metabolism Service, Department of Medicine, Hadassah - Hebrew University Medical Center, Jerusalem, Israel
| | - Gil Leibowitz
- Endocrinology and Metabolism Service, Department of Medicine, Hadassah - Hebrew University Medical Center, Jerusalem, Israel
- * E-mail:
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24
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Karslioglu E, Kleinberger JW, Salim FG, Cox AE, Takane KK, Scott DK, Stewart AF. cMyc is a principal upstream driver of beta-cell proliferation in rat insulinoma cell lines and is an effective mediator of human beta-cell replication. Mol Endocrinol 2011; 25:1760-72. [PMID: 21885567 DOI: 10.1210/me.2011-1074] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Adult human β-cells replicate slowly. Also, despite the abundance of rodent β-cell lines, there are no human β-cell lines for diabetes research or therapy. Prior studies in four commonly studied rodent β-cell lines revealed that all four lines displayed an unusual, but strongly reproducible, cell cycle signature: an increase in seven G(1)/S molecules, i.e. cyclins A, D3, and E, and cdk1, -2, -4, and -6. Here, we explore the upstream mechanism(s) that drive these cell cycle changes. Using biochemical, pharmacological and molecular approaches, we surveyed potential upstream mitogenic signaling pathways in Ins 1 and RIN cells. We used both underexpression and overexpression to assess effects on rat and human β-cell proliferation, survival and cell cycle control. Our results indicate that cMyc is: 1) uniquely up-regulated among other candidates; 2) principally responsible for the increase in the seven G(1)/S molecules; and, 3) largely responsible for proliferation in rat β-cell lines. Importantly, cMyc expression in β-cell lines, although some 5- to 7-fold higher than normal rat β-cells, is far below the levels (75- to 150-fold) previously associated with β-cell death and dedifferentiation. Notably, modest overexpression of cMyc is able to drive proliferation without cell death in normal rat and human β-cells. We conclude that cMyc is an important driver of replication in the two most commonly employed rat β-cell lines. These studies reverse the current paradigm in which cMyc overexpression is inevitably associated with β-cell death and dedifferentiation. The cMyc pathway provides potential approaches, targets, and tools for driving and sustaining human β-cell replication.
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Affiliation(s)
- Esra Karslioglu
- Division of Endocrinology, the University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
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25
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Poupeau A, Postic C. Cross-regulation of hepatic glucose metabolism via ChREBP and nuclear receptors. Biochim Biophys Acta Mol Basis Dis 2011; 1812:995-1006. [PMID: 21453770 DOI: 10.1016/j.bbadis.2011.03.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/21/2011] [Accepted: 03/22/2011] [Indexed: 01/17/2023]
Abstract
There is a worldwide epidemic of obesity and type 2 diabetes, two major public health concerns associated with alterations in both insulin and glucose signaling pathways. Glucose is not only an energy source but also controls the expression of key genes involved in energetic metabolism, through the glucose-signaling transcription factor, Carbohydrate Responsive Element Binding Protein (ChREBP). ChREBP has emerged as a central regulator of de novo fatty acid synthesis (lipogenesis) in response to glucose under both physiological and physiopathological conditions. Glucose activates ChREBP by regulating its entry from the cytosol to the nucleus, thereby promoting its binding to carbohydrate responsive element (ChoRE) in the promoter regions of glycolytic (L-PK) and lipogenic genes (ACC and FAS). We have previously reported that the inhibition of ChREBP in liver of obese ob/ob mice improves the metabolic alterations linked to obesity, fatty liver and insulin-resistance. Therefore, regulating ChREBP activity could be an attractive target for lipid-lowering therapies in obesity and diabetes. However, before this is possible, a better understanding of the mechanism(s) regulating its activity is needed. In this review, we summarize recent findings on the role and regulation of ChREBP and particularly emphasize on the cross-regulations that may exist between key nuclear receptors (LXR, TR, HNF4α) and ChREBP for the control of hepatic glucose metabolism. These novel molecular cross-talks may open the way to new pharmacological opportunities. This article is part of a Special Issue entitled: Translating nuclear receptors from health to disease.
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26
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Davies MN, O'Callaghan BL, Towle HC. Activation and repression of glucose-stimulated ChREBP requires the concerted action of multiple domains within the MondoA conserved region. Am J Physiol Endocrinol Metab 2010; 299:E665-74. [PMID: 20682844 PMCID: PMC2957870 DOI: 10.1152/ajpendo.00349.2010] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carbohydrate response element-binding protein (ChREBP) is a glucose-dependent transcription factor that stimulates the expression of glycolytic and lipogenic genes in mammals. Glucose regulation of ChREBP has been mapped to its conserved NH(2)-terminal region of 300 amino acids, designated the MondoA conserved region (MCR). Within the MCR, five domains (MCR1-5) have a particularly high level of conservation and are likely to be important for glucose regulation. We carried out a large-scale deletion and substitution mutational analysis of the MCR domain of ChREBP. This analysis revealed that MCRs 1-4 function in a concerted fashion to repress ChREBP activity in basal (nonstimulatory) conditions. Deletion of the entire MCR1-4 segment or the combination of four specific point mutations located across this region leads to a highly active, glucose-independent form of ChREBP. However, deletion of any individual MCR domain and the majority of point mutations throughout MCR1-4 rendered ChREBP inactive. These observations suggest that the MCR1-4 region interacts with an additional coregulatory factor required for activation. This possibility is supported by the observation that the MCR1-4 region can compete for activity with wild-type ChREBP in stimulatory conditions. In contrast, mutations in the MCR5 domain result in increased activity, suggesting that this domain may be the target of intramolecular repression in basal conditions. Thus, the MCR domains act in a complex and coordinated manner to regulate ChREBP activity in response to glucose.
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Affiliation(s)
- Michael N Davies
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
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27
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Zhang P, Metukuri MR, Bindom SM, Prochownik EV, O'Doherty RM, Scott DK. c-Myc is required for the CHREBP-dependent activation of glucose-responsive genes. Mol Endocrinol 2010; 24:1274-86. [PMID: 20382893 DOI: 10.1210/me.2009-0437] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Glucose regulates programs of gene expression that orchestrate changes in cellular phenotype in several metabolically active tissues. Carbohydrate response element-binding protein (ChREBP) and its binding partner, Mlx, mediate glucose-regulated gene expression by binding to carbohydrate response elements on target genes, such as the prototypical glucose-responsive gene, liver-type pyruvate kinase (Pklr). c-Myc is also required for the glucose response of the Pklr gene, although the relationship between c-Myc and ChREBP has not been defined. Here we describe the molecular events of the glucose-mediated activation of Pklr and determine the effects of decreasing the activity or abundance of c-Myc on this process. Time-course chromatin immunoprecipitation revealed a set of transcription factors [hepatocyte nuclear factor (HNF)1alpha, HNF4alpha, and RNA polymerase II (Pol II)] constitutively resident on the Pklr promoter, with a relative enrichment of acetylated histones 3 and 4 in the same region of the gene. Glucose did not affect HNF1alpha binding or the acetylation of histones H3 or H4. By contrast, glucose promoted the recruitment of ChREBP and c-Myc and increased the occupancy of HNF4alpha and RNA Pol II, which were coincident with the glucose-mediated increase in transcription as determined by a nuclear run-on assay. Depletion of c-Myc activity using a small molecule inhibitor (10058-F4/1RH) abolished the glucose-mediated recruitment of HNF4alpha, ChREBP, and RNA Pol II, without affecting basal gene expression, histone acetylation, and HNF1alpha or basal HNF4alpha occupancy. The activation and recruitment of ChREBP to several glucose-responsive genes were blocked by 1RH, indicating a general necessity for c-Myc in this process.
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Affiliation(s)
- Pili Zhang
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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28
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Glucose induces expression of rat pyruvate carboxylase through a carbohydrate response element in the distal gene promoter. Biochem J 2010; 426:159-70. [PMID: 20001964 DOI: 10.1042/bj20091266] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pyruvate carboxylase is an enzyme of the so-called pyruvate cycling pathways, which have been proposed to contribute to glucose-stimulated insulin secretion in pancreatic beta-cells. In the rat insulinoma cell line 832/13, transcripts from both the distal and proximal gene promoter for pyruvate carboxylase are up-regulated by glucose, with pyruvate carboxylase being expressed mainly from the distal gene promoter. At position -408 to -392 relative to the transcription start site, the distal gene promoter was found to contain a ChoRE (carbohydrate response element). Its deletion abolishes glucose responsiveness of the promoter, and the sequence can mediate glucose responsiveness to a heterologous gene promoter. ChREBP (carbohydrate response element-binding protein) and its dimerization partner Mlx (Max-like protein X) bind to the ChoRE in vitro. ChREBP further binds to the distal promoter region at a high glucose concentration in situ. The E-box-binding transcription factors USF1/2 (upstream stimulatory factor 1/2) and E2A variant 2 [also known as E47 and TCF3 (transcription factor 3)] can also bind to the ChoRE. Overexpression of E2A diminishes the magnitude of the glucose response from the pyruvate carboxylase ChoRE. This illustrates that competition between ChREBP-Mlx and other factors binding to the ChoRE affects glucose responsiveness. We conclude that a ChoRE in the distal gene promoter contributes to the glucose-mediated expression of pyruvate carboxylase.
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29
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Noordeen NA, Khera TK, Sun G, Longbottom ER, Pullen TJ, da Silva Xavier G, Rutter GA, Leclerc I. Carbohydrate-responsive element-binding protein (ChREBP) is a negative regulator of ARNT/HIF-1beta gene expression in pancreatic islet beta-cells. Diabetes 2010; 59:153-60. [PMID: 19833882 PMCID: PMC2797916 DOI: 10.2337/db08-0868] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Carbohydrate-responsive element-binding protein (ChREBP) is a transcription factor that has been shown to regulate carbohydrate metabolism in the liver and pancreatic beta-cells in response to elevated glucose concentrations. Because few genes have been identified so far as bona fide ChREBP-target genes, we have performed a genome-wide analysis of the ChREBP transcriptome in pancreatic beta-cells. RESEARCH DESIGN AND METHODS Chromatin immunoprecipitation and high-density oligonucleotide tiling arrays (ChIP-chip; Agilent Technologies) using MIN6 pancreatic beta-cell extracts were performed together with transcriptional and other analysis using standard techniques. RESULTS One of the genes identified by ChIP-chip and linked to glucose sensing and insulin secretion was aryl hydrocarbon receptor nuclear translocator (ARNT)/hypoxia-inducible factor-1beta (HIF-1beta), a transcription factor implicated in altered gene expression and pancreatic-islet dysfunction in type 2 diabetes. We first confirmed that elevated glucose concentrations decreased ARNT/HIF-1beta levels in INS-1 (832/13) cells and primary mouse islets. Demonstrating a role for ChREBP in ARNT gene regulation, ChREBP silencing increased ARNT mRNA levels in INS-1 (832/13) cells, and ChREBP overexpression decreased ARNT mRNA in INS-1 (832/13) cells and primary mouse islets. We demonstrated that ChREBP and Max-like protein X (MLX) bind on the ARNT/HIF-1beta promoter on the proximal region that also confers the negative glucose responsiveness. CONCLUSIONS These results demonstrate that ChREBP acts as a novel repressor of the ARNT/HIF-1beta gene and might contribute to beta-cell dysfunction induced by glucotoxicity.
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Affiliation(s)
- Nafeesa A. Noordeen
- Department of Endocrinology and Metabolic Medicine, Division of Medicine, Imperial College, London, U.K
| | - Tarnjit K. Khera
- Department of Cellular and Molecular Medicine, University of Bristol, Bristol, U.K
| | - Gao Sun
- Department of Cell Biology, Division of Medicine, Imperial College, London, U.K
| | | | - Timothy J. Pullen
- Department of Cell Biology, Division of Medicine, Imperial College, London, U.K
| | | | - Guy A. Rutter
- Department of Cell Biology, Division of Medicine, Imperial College, London, U.K
| | - Isabelle Leclerc
- Department of Endocrinology and Metabolic Medicine, Division of Medicine, Imperial College, London, U.K
- Corresponding author: Isabelle Leclerc,
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30
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The glucose-responsive transcription factor ChREBP contributes to glucose-dependent anabolic synthesis and cell proliferation. Proc Natl Acad Sci U S A 2009; 106:21660-5. [PMID: 19995986 DOI: 10.1073/pnas.0911316106] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Tumor cells are metabolically reprogrammed to fuel cell proliferation. Most transformed cells take up high levels of glucose and produce ATP through aerobic glycolysis. In cells exhibiting aerobic glycolysis, a significant fraction of glucose carbon is also directed into de novo lipogenesis and nucleotide biosynthesis. The glucose-responsive transcription factor carbohydrate responsive element binding protein (ChREBP) was previously shown to be important for redirecting glucose metabolism in support of lipogenesis in nonproliferating hepatocytes. However, whether it plays a more generalized role in reprogramming metabolism during cell proliferation has not been examined. Here, we demonstrated that the expression of ChREBP can be induced in response to mitogenic stimulation and that the induction of ChREBP is required for efficient cell proliferation. Suppression of ChREBP resulted in diminished aerobic glycolysis, de novo lipogenesis, and nucleotide biosynthesis, but stimulated mitochondrial respiration, suggesting a metabolic switch from aerobic glycolysis to oxidative phosphorylation. Cells in which ChREBP was suppressed by RNAi exhibited p53 activation and cell cycle arrest. In vivo, suppression of ChREBP led to a p53-dependent reduction in tumor growth. These results demonstrate that ChREBP plays a key role both in redirecting glucose metabolism to anabolic pathways and suppressing p53 activity.
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Burke SJ, Collier JJ, Scott DK. cAMP prevents glucose-mediated modifications of histone H3 and recruitment of the RNA polymerase II holoenzyme to the L-PK gene promoter. J Mol Biol 2009; 392:578-88. [PMID: 19631660 DOI: 10.1016/j.jmb.2009.07.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2009] [Revised: 07/16/2009] [Accepted: 07/17/2009] [Indexed: 10/20/2022]
Abstract
Glucose and cAMP reciprocally regulate expression of the L-type pyruvate kinase (L-PK) gene by controlling the formation of a complex containing the carbohydrate response element binding protein (ChREBP) and the coactivator CREB binding protein (CBP) on the L-PK promoter. However, the role of posttranslational histone modifications on the opposing effects of glucose and cAMP on the L-PK gene is unknown. Using the highly glucose-sensitive 832/13 rat insulinoma cell line, we demonstrated that glucose regulates acetylation and methylation of various histone residues at the L-PK gene promoter. These glucose-dependent histone modifications correlated with an increase in the recruitment and phosphorylation of RNA polymerase II (Pol II) on the L-PK gene promoter. Conversely, the cAMP agonist forskolin prevented glucose-mediated expression of the L-PK gene by decreasing the acetylation of histones H3 and H4 on the promoter, decreasing the methylation of H3-K4 on the coding region, and increasing the methylation of H3-K9 on the coding region. These changes induced by cAMP culminated with a decrease in the glucose-dependent recruitment of phosphorylated Pol II to the L-PK gene promoter. Furthermore, maneuvers that interfere with the glucose-dependent assembly of ChREBP and CBP on the L-PK promoter, such as increasing intracellular cAMP levels, overexpression of a dominant-negative form of ChREBP, and small-interfering-RNA-mediated suppression of CBP abundance, all altered the acetylation and methylation of histones on the L-PK promoter, which decreased Pol II recruitment and subsequently inhibited transcriptional activation of the L-PK gene. We conclude that the effects of glucose and cAMP are mediated in part by epigenetic modulation of histones.
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Affiliation(s)
- Susan J Burke
- Department of Medicine, University of Pittsburgh, PA 15261, USA
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Lee AH, Glimcher LH. Intersection of the unfolded protein response and hepatic lipid metabolism. Cell Mol Life Sci 2009; 66:2835-50. [PMID: 19468685 DOI: 10.1007/s00018-009-0049-8] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Revised: 05/05/2009] [Accepted: 05/06/2009] [Indexed: 12/20/2022]
Abstract
The liver plays a central role in whole-body lipid metabolism by governing the synthesis, oxidization, transport and excretion of lipids. The unfolded protein response (UPR) was identified as a signal transduction system that is activated by ER stress. Recent studies revealed a critical role of the UPR in hepatic lipid metabolism. The IRE1/XBP1 branch of the UPR is activated by high dietary carbohydrates and controls the expression of genes involved in fatty acid and cholesterol biosynthesis. PERK mediated eIF2alpha phosphorylation is also required for the expression of lipogenic genes and the development of hepatic steatosis, likely by activating C/EBP and PPARgamma transcription factors. Further studies to define the molecular pathways that lead to the activation of the UPR by nutritional cues in the liver, and their contribution to human metabolic disorders such as hepatic steatosis, atherosclerosis and type 2 diabetes that are associated with dysregulation of lipid homeostasis, are warranted.
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Affiliation(s)
- Ann-Hwee Lee
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115-6017, USA.
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Burke SJ, Collier JJ, Scott DK. cAMP opposes the glucose-mediated induction of the L-PK gene by preventing the recruitment of a complex containing ChREBP, HNF4alpha, and CBP. FASEB J 2009; 23:2855-65. [PMID: 19406844 DOI: 10.1096/fj.08-126631] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Glucose-mediated activation of the L-type pyruvate kinase (L-PK) gene is repressed by cAMP, making this an excellent model for studying the mechanism by which these contrary signals regulate gene expression. Using the 832/13 rat insulinoma cell line, we demonstrate using RNA interference and chromatin immunoprecipitation that carbohydrate response element binding protein (ChREBP), hepatic nuclear factor 4alpha (HNF4alpha), and the coactivator CREB binding protein (CBP) are required for the glucose response of the L-PK gene and are recruited to the promoter by glucose. The cAMP agonist forskolin blocked the glucose-mediated induction of the L-PK gene in a PKA-dependent manner and blocked the recruitment of ChREBP, HNF4alpha, and CBP to the L-PK promoter, while simultaneously recruiting CBP to the cAMP-inducible gene, nuclear receptor subfamily 4, group A, member 2 (NR4A2). Overexpression of CBP, but not ChREBP, reversed the cAMP repression of the L-PK gene. In addition, CBP augmented the glucose response of the L-PK promoter. We conclude that cAMP and glucose signaling converge on a complex containing ChREBP, HNF4alpha, and CBP, and that cAMP acts by disrupting this transcriptional complex assembled by glucose-derived signals.
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Affiliation(s)
- Susan J Burke
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
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Liu Y, Yang HW, Meng Y. Over-expression of CDK11p58 gene suppresses the proliferation of rat insulinoma cell line INS-1. Shijie Huaren Xiaohua Zazhi 2009; 17:873-876. [DOI: 10.11569/wcjd.v17.i9.873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To observe the influences of CDK11p58 gene on the proliferation and cell cycle of rat insulinoma cell line INS-1.
METHODS: Rat insulinoma INS-1 cells were divided into three groups: the experimental group transfected with plasmid pcDNA3.0-CDK11p58; empty vector group transfected with pcDNA3.0; blank control group without any interference. After 48 hours, the expression of CDK11p58 was detected by Western blot. The proliferation activities of the INS-1 cells cells were assessed by the MTT assay. Cell cycle was analyzed by flow cytometry.
RESULTS: In comparison with that in the empty vector group, the expression of CDK11p58 gene were significantly up-regulated in the experimental group after 48-h transfection (P < 0.01). Over-expression of CDK11p58 gene suppressed the growth of INS-1 cells (P < 0.05), and increased the G1-phase cell proportion significantly (69.87% ± 1.77% vs 63.03% ± 2.66%, P < 0.01). INS-1 cells were partly blocked at G1 phase.
CONCLUSION: CDK11p58 gene is involved in the proliferation activity of INS-1 cells. Over-expression of CDK11p58 gene may suppress INS-1 cell growth and the mechanisms may be due to the G1 phase arrest.
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Graves JA, Metukuri M, Scott D, Rothermund K, Prochownik EV. Regulation of reactive oxygen species homeostasis by peroxiredoxins and c-Myc. J Biol Chem 2008; 284:6520-9. [PMID: 19098005 DOI: 10.1074/jbc.m807564200] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peroxiredoxins (Prxs) are highly conserved proteins found in most organisms, where they function primarily to scavenge reactive oxygen species (ROS). Loss of the most ubiquitous member of the family, Prx1, is associated with the accumulation of oxidatively damaged DNA and a tumor-prone phenotype. Prx1 interacts with the transcriptional regulatory domain of the c-Myc oncoprotein and suppresses its transforming activity. The DNA damage in tissues of prx1-/- mice is associated in some cases with only modest increases in total ROS levels. However, these cells show dramatic increases in nuclear ROS and reduced levels of cytoplasmic ROS, which explains their mutational susceptibility. In the current work, we have investigated whether changes in other ROS scavengers might account for the observed ROS redistribution pattern in prx1-/- cells. We show approximately 5-fold increases in Prx5 levels in prx1-/- embryo fibroblasts relative to prx1+/+ cells. Moreover, Prx5 levels normalize when Prx1 expression is restored. Prx5 levels also appear to be highly dependent on c-Myc, and chromatin immunoprecipitation experiments showed differential occupancy of c-Myc and Prx1 complexes at E-box elements in the prx5 gene proximal promoter. This study represents a heretofore unreported mechanism for the c-Myc-dependent regulation of one Prx family member by another and identifies a novel means by which cells reestablish ROS homeostasis when one of these family members is compromised.
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Affiliation(s)
- J Anthony Graves
- Department of Pediatrics, Division of Hematology/Oncology, Children's Hospital of Pittsburgh, and University of Pittsburgh Medical Center, Department of Microbiology and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
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Davies MN, O'Callaghan BL, Towle HC. Glucose activates ChREBP by increasing its rate of nuclear entry and relieving repression of its transcriptional activity. J Biol Chem 2008; 283:24029-38. [PMID: 18591247 DOI: 10.1074/jbc.m801539200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Carbohydrate response element-binding protein (ChREBP) is a glucose-responsive transcription factor that activates genes involved in de novo lipogenesis in mammals. The current model for glucose activation of ChREBP proposes that increased glucose metabolism triggers a cytoplasmic to nuclear translocation of ChREBP that is critical for activation. However, we find that ChREBP actively shuttles between the cytoplasm and nucleus in both low and high glucose in the glucose-sensitive beta cell-derived line, 832/13. Glucose stimulates a 3-fold increase in the rate of ChREBP nuclear entry, but trapping ChREBP in the nucleus by mutagenesis or with a nuclear export inhibitor does not lead to constitutive activation. In fact, mutational studies targeting the nuclear export signal of ChREBP also identified a distinct function essential for glucose-dependent transcriptional activation. From this, we conclude that an additional event independent of nuclear translocation is required for activation. The N-terminal segment of ChREBP (amino acids 1-298) has previously been shown to repress activity under basal conditions. This segment has five highly conserved regions, Mondo conserved regions 1-5 (MCR1 to -5). Based on activating mutations in MCR2 and MCR5, we propose that these two regions act coordinately to repress ChREBP in low glucose. In addition, other mutations in MCR2 and mutations in MCR3 were found to prevent glucose activation. Hence, we conclude that both relief of repression and adoption of an activating form are required for ChREBP activation.
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Affiliation(s)
- Michael N Davies
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street SE, Minneapolis, MN 55455, USA
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Eckert DT, Zhang P, Collier JJ, O'Doherty RM, Scott DK. Detailed molecular analysis of the induction of the L-PK gene by glucose. Biochem Biophys Res Commun 2008; 372:131-6. [PMID: 18468514 DOI: 10.1016/j.bbrc.2008.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 05/01/2008] [Indexed: 01/22/2023]
Abstract
Glucose has powerful effects on gene expression and participates in the fasted-to-fed transition of the liver. However, the molecular mechanism of glucose-regulated gene expression has not been completely described. In the present study, we performed a detailed analysis of the molecular events of the insulin-independent glucose response of the liver-type pyruvate kinase (L-PK) gene. L-PK mRNA was increased by glucose at the transcriptional level as determined by real-time RT-PCR, mRNA stability measurements, and nuclear run-on assays. LY294002 and LY303511 inhibited the glucose response of the L-PK gene at the transcriptional level. Histones H3 and H4 associated with the L-PK gene promoter were hyperacetylated and HNF4alpha was constitutively bound in low and high glucose. Treatment with 20mM glucose increased recruitment of ChREBP, additional HNF4alpha, and RNA polymerase II. Glucose-stimulated the phosphorylation of the C-terminal domain of RNA polymerase II, with increased Ser5 phosphorylation near the transcription start site and increased Ser2 phosphorylation near the termination signal. LY294002 and LY303511 blocked the recruitment of RNA polymerase II to the L-PK gene, reducing the rate of transcription. The results of these studies demonstrate fundamental details of the molecular mechanism of glucose activated gene expression.
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Affiliation(s)
- David T Eckert
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, New Orleans, LA, USA
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Identification and function of phosphorylation in the glucose-regulated transcription factor ChREBP. Biochem J 2008; 411:261-70. [PMID: 18215143 DOI: 10.1042/bj20071156] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the liver, induction of genes encoding enzymes involved in de novo lipogenesis occurs in response to increased glucose metabolism. ChREBP (carbohydrate-response-element-binding protein) is a basic helix-loop-helix/leucine zipper transcription factor that regulates expression of these genes. To evaluate the potential role of ChREBP phosphorylation in its regulation, we used MS to identify modified residues. In the present paper, we report the detection of multiple phosphorylation sites of ChREBP expressed in hepatocytes, several of which are only observed under high-glucose conditions. Mutation of each of these serine/threonine residues of ChREBP did not alter its ability to respond to glucose. However, mutation of five N-terminal phosphoacceptor sites resulted in a major decrease in activity under high-glucose conditions. These phosphorylated residues are located within a region of ChREBP (amino acids 1-197) that is critical for glucose regulation. Mutation of Ser(56) within this region to an aspartate residue resulted in increased nuclear accumulation and activity under high-glucose conditions. Together, these data suggest that ChREBP activity is regulated by complex multisite phosphorylation patterns involving its N-terminal regulatory region.
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