RESUMO
AIMS/HYPOTHESIS: Energy-dense diets that are high in fat are associated with a risk of metabolic diseases. The underlying molecular mechanisms could involve epigenetics, as recent data show altered DNA methylation of putative type 2 diabetes candidate genes in response to high-fat diets. We examined the effect of a short-term high-fat overfeeding (HFO) diet on genome-wide DNA methylation patterns in human skeletal muscle. METHODS: Skeletal muscle biopsies were obtained from 21 healthy young men after ingestion of a short-term HFO diet and a control diet, in a randomised crossover setting. DNA methylation was measured in 27,578 CpG sites/14,475 genes using Illumina's Infinium Bead Array. Candidate gene expression was determined by quantitative real-time PCR. RESULTS: HFO introduced widespread DNA methylation changes affecting 6,508 genes (45%), with a maximum methylation change of 13.0 percentage points. The HFO-induced methylation changes were only partly and non-significantly reversed after 6-8 weeks. Alterations in DNA methylation levels primarily affected genes involved in inflammation, the reproductive system and cancer. Few gene expression changes were observed and these had poor correlation to DNA methylation. CONCLUSIONS/INTERPRETATION: The genome-wide DNA methylation changes induced by the short-term HFO diet could have implications for our understanding of transient epigenetic regulation in humans and its contribution to the development of metabolic diseases. The slow reversibility suggests a methylation build-up with HFO, which over time may influence gene expression levels.
Assuntos
Metilação de DNA , Dieta Hiperlipídica , Músculo Esquelético/metabolismo , Proteínas de Transporte de Cátions/genética , Ilhas de CpG/genética , Estudos Cross-Over , Inibidor de Quinase Dependente de Ciclina p15/genética , Inibidor p16 de Quinase Dependente de Ciclina/genética , Metilação de DNA/genética , Epigênese Genética , Expressão Gênica , Proteínas de Choque Térmico/genética , Proteínas de Homeodomínio/genética , Humanos , Resistência à Insulina/genética , Masculino , Músculo Esquelético/fisiologia , Hipernutrição , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Proteínas Proto-Oncogênicas c-akt/genética , Reação em Cadeia da Polimerase em Tempo Real , Transativadores/genética , Fatores de Transcrição/genética , Adulto Jovem , Transportador 8 de ZincoRESUMO
Epigenetics comprises various mechanisms that mold chromatin structures and regulate gene expression with stability, thus defining cell identity and function and adapting cells to environmental changes. Alteration of these mechanisms contributes to the inception of various pathological conditions. Given the complexity of the immune system, one would predict that a higher-order, supragenetic regulation is indispensable for generation of its constituents and control of its functions. Here, we summarize various aspects of immune system physiology and pathology in which epigenetic pathways have been implicated. Increasing knowledge in this field, together with the development of specific tools with which to manipulate epigenetic pathways, might form a basis for new strategies of immune function modulation, both to optimize immune therapies for infections or cancer and to control immune alterations in aging or autoimmunity.
Assuntos
Autoimunidade , Epigênese Genética/imunologia , Doenças do Sistema Imunitário/imunologia , Infecções/imunologia , Neoplasias/imunologia , Animais , Cromatina/genética , Cromatina/imunologia , Epigênese Genética/genética , Humanos , Doenças do Sistema Imunitário/genética , Infecções/genética , Neoplasias/genéticaRESUMO
Sirtuin 1 (Sirt1) and Sirtuin 2 (Sirt2) belong to the family of NAD+ (nicotinamide adenine dinucleotide-positive)-dependent class III histone deacetylases and are involved in regulating lifespan. As cancer is a disease of ageing, targeting Sirtuins is emerging as a promising antitumour strategy. Here we present Salermide (N-{3-[(2-hydroxy-naphthalen-1-ylmethylene)-amino]-phenyl}-2-phenyl-propionamide), a reverse amide with a strong in vitro inhibitory effect on Sirt1 and Sirt2. Salermide was well tolerated by mice at concentrations up to 100 muM and prompted tumour-specific cell death in a wide range of human cancer cell lines. The antitumour activity of Salermide was primarily because of a massive induction of apoptosis. This was independent of global tubulin and K16H4 acetylation, which ruled out a putative Sirt2-mediated apoptotic pathway and suggested an in vivo mechanism of action through Sirt1. Consistently with this, RNA interference-mediated knockdown of Sirt1, but not Sirt2, induced apoptosis in cancer cells. Although p53 has been reported to be a target of Sirt1, genetic p53 knockdowns showed that the Sirt1-dependent proapoptotic effect of Salermide is p53-independent. We were finally able to ascribe the apoptotic effect of Salermide to the reactivation of proapoptotic genes epigenetically repressed exclusively in cancer cells by Sirt1. Taken together, our results underline Salermide's promise as an anticancer drug and provide evidence for the molecular mechanism through which Sirt1 is involved in human tumorigenesis.
