Parrillo L, Costa V, Raciti G A, Longo M, Spinelli R, Esposito R, Nigro C, Vastolo V, Desiderio A, Zatterale F, Ciccodicola A, Formisano P, Miele C, Beguinot F
Dipartimento di Scienze Mediche e Traslazionali dell'Università di Napoli 'Federico II', Naples, Italy.
URT dell'Istituto di Endocrinologia e Oncologia Sperimentale 'Gaetano Salvatore', Consiglio Nazionale delle Ricerche, Naples, Italy.
Int J Obes (Lond). 2016 Jun;40(6):929-37. doi: 10.1038/ijo.2016.36. Epub 2016 Mar 16.
BACKGROUND/OBJECTIVES: The genomic bases of the adipose tissue abnormalities induced by chronic positive calorie excess have been only partially elucidated. We adopted a genome-wide approach to directly test whether long-term high-fat diet (HFD) exposure affects the DNA methylation profile of the mouse adipose tissue and to identify the functional consequences of these changes.
SUBJECTS/METHODS: We have used epididymal fat of mice fed either high-fat (HFD) or regular chow (STD) diet for 5 months and performed genome-wide DNA methylation analyses by methylated DNA immunoprecipitation sequencing (MeDIP-seq). Mouse Homeobox (Hox) Gene DNA Methylation PCR, RT-qPCR and bisulphite sequencing analyses were then performed.
Mice fed the HFD progressively expanded their adipose mass accompanied by a significant decrease in glucose tolerance (P<0.001) and insulin sensitivity (P<0.05). MeDIP-seq data analysis revealed a uniform distribution of differentially methylated regions (DMR) through the entire adipocyte genome, with a higher number of hypermethylated regions in HFD mice (P<0.005). This different methylation profile was accompanied by increased expression of the Dnmt3a DNA methyltransferase (Dnmt; P<0.05) and the methyl-CpG-binding domain protein Mbd3 (P<0.05) genes in HFD mice. Gene ontology analysis revealed that, in the HFD-treated mice, the Hox family of development genes was highly enriched in differentially methylated genes (P=0.008). To validate this finding, Hoxa5, which is implicated in fat tissue differentiation and remodeling, has been selected and analyzed by bisulphite sequencing, confirming hypermethylation in the adipose tissue from the HFD mice. Hoxa5 hypermethylation was associated with downregulation of Hoxa5 mRNA and protein expression. Feeding animals previously exposed to the HFD with a standard chow diet for two further months improved the metabolic phenotype of the animals, accompanied by return of Hoxa5 methylation and expression levels (P<0.05) to values similar to those of the control mice maintained under standard chow.
HFD induces adipose tissue abnormalities accompanied by epigenetic changes at the Hoxa5 adipose tissue remodeling gene.
背景/目的：慢性正热量过剩所致脂肪组织异常的基因组基础仅得到部分阐明。我们采用全基因组方法直接检测长期高脂饮食（HFD）暴露是否会影响小鼠脂肪组织的DNA甲基化谱，并确定这些变化的功能后果。
受试者/方法：我们使用了喂食高脂（HFD）或常规饲料（STD）5个月的小鼠附睾脂肪，并通过甲基化DNA免疫沉淀测序（MeDIP-seq）进行全基因组DNA甲基化分析。随后进行小鼠同源框（Hox）基因DNA甲基化PCR、RT-qPCR和亚硫酸氢盐测序分析。
喂食HFD的小鼠脂肪量逐渐增加，同时葡萄糖耐量（P<0.001）和胰岛素敏感性（P<0.05）显著降低。MeDIP-seq数据分析显示，差异甲基化区域（DMR）在整个脂肪细胞基因组中均匀分布，HFD小鼠中高甲基化区域数量更多（P<0.005）。这种不同的甲基化谱伴随着HFD小鼠中Dnmt3a DNA甲基转移酶（Dnmt；P<0.05）和甲基-CpG结合域蛋白Mbd3（P<0.05）基因表达增加。基因本体分析显示，在HFD处理的小鼠中，发育基因的Hox家族在差异甲基化基因中高度富集（P=0.008）。为验证这一发现，选择了与脂肪组织分化和重塑有关的Hoxa5，并通过亚硫酸氢盐测序进行分析，证实HFD小鼠脂肪组织中存在高甲基化。Hoxa5高甲基化与Hoxa5 mRNA和蛋白表达下调相关。给先前暴露于HFD的动物再喂食标准饲料两个月可改善动物的代谢表型，同时Hoxa5甲基化和表达水平（P<0.05）恢复到与维持在标准饲料下的对照小鼠相似的值。
HFD诱导脂肪组织异常，并伴有Hoxa5脂肪组织重塑基因的表观遗传变化。
