SIRT1 Limits Adipocyte Hyperplasia through c-Myc Inhibition.

Autor:	Abdesselem H; From the Departments of Microbiology and Immunology., Madani A; From the Departments of Microbiology and Immunology., Hani A; From the Departments of Microbiology and Immunology., Al-Noubi M; Biochemistry, and., Goswami N; Biochemistry, and., Ben Hamidane H; Biochemistry, and., Billing AM; Biochemistry, and., Pasquier J; Genetic Medicine, Weill Cornell Medicine Qatar, Qatar Foundation, Education City, P.O. Box 24144, Doha, Qatar., Bonkowski MS; the Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, and., Halabi N; Genetic Medicine, Weill Cornell Medicine Qatar, Qatar Foundation, Education City, P.O. Box 24144, Doha, Qatar., Dalloul R; From the Departments of Microbiology and Immunology., Sheriff MZ; From the Departments of Microbiology and Immunology., Mesaeli N; Biochemistry, and., ElRayess M; the Life Sciences Research Division, Anti-Doping Lab Qatar, P.O. Box 27775, Doha, Qatar., Sinclair DA; the Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, and., Graumann J; Biochemistry, and., Mazloum NA; From the Departments of Microbiology and Immunology, nam2016@qatar-med.cornell.edu.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2016 Jan 29; Vol. 291 (5), pp. 2119-35. Date of Electronic Publication: 2015 Dec 11.
DOI:	10.1074/jbc.M115.675645
Abstrakt:	The expansion of fat mass in the obese state is due to increased adipocyte hypertrophy and hyperplasia. The molecular mechanism that drives adipocyte hyperplasia remains unknown. The NAD(+)-dependent protein deacetylase sirtuin 1 (SIRT1), a key regulator of mammalian metabolism, maintains proper metabolic functions in many tissues, counteracting obesity. Here we report that differentiated adipocytes are hyperplastic when SIRT1 is knocked down stably in mouse 3T3-L1 preadipocytes. This phenotype is associated with dysregulated adipocyte metabolism and enhanced inflammation. We also demonstrate that SIRT1 is a key regulator of proliferation in preadipocytes. Quantitative proteomics reveal that the c-Myc pathway is altered to drive enhanced proliferation in SIRT1-silenced 3T3-L1 cells. Moreover, c-Myc is hyperacetylated, levels of p27 are reduced, and cyclin-dependent kinase 2 (CDK2) is activated upon SIRT1 reduction. Remarkably, differentiating SIRT1-silenced preadipocytes exhibit enhanced mitotic clonal expansion accompanied by reduced levels of p27 as well as elevated levels of CCAAT/enhancer-binding protein β (C/EBPβ) and c-Myc, which is also hyperacetylated. c-Myc activation and enhanced proliferation phenotype are also found to be SIRT1-dependent in proliferating mouse embryonic fibroblasts and differentiating human SW872 preadipocytes. Reducing both SIRT1 and c-Myc expression in 3T3-L1 cells simultaneously does not induce the adipocyte hyperplasia phenotype, confirming that SIRT1 controls adipocyte hyperplasia through c-Myc regulation. A better understanding of the molecular mechanisms of adipocyte hyperplasia will open new avenues toward understanding obesity. (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)
Databáze:	MEDLINE
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