Kurylowicz A, Owczarz M, Polosak J, Jonas M I, Lisik W, Jonas M, Chmura A, Puzianowska-Kuznicka M
Department of Human Epigenetics, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland.
Department of General and Transplantation Surgery, Medical University of Warsaw, Warsaw, Poland.
Int J Obes (Lond). 2016 Nov;40(11):1635-1642. doi: 10.1038/ijo.2016.131. Epub 2016 Aug 2.
BACKGROUND/OBJECTIVE: Given their importance in the regulation of metabolism, sirtuins (SIRTs) constitute promising subjects of research on the pathogenesis of obesity and the metabolic syndrome. The aim of this study was to assess whether obesity in humans is associated with changes in the expression of SIRT genes in adipose tissue and whether epigenetic mechanisms, DNA methylation and microRNA (miRNA) interference, mediate in this phenomenon.
SUBJECTS/METHODS: The expression of SIRTs and of SIRT1 and SIRT7 mRNA-interacting miRNAs was evaluated by real-time PCR in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) of 58 obese (body mass index (BMI) >40 kg m) and 31 normal-weight (BMI 20-24.9 kg m) individuals. The methylation status of SIRTs was studied by the methylation-sensitive digestion/real-time PCR method.
SIRT1 mRNA levels were lower in adipose tissues of obese patients than of normal-weight controls (VAT: P=0.0002, SAT: P=0.008). In contrast, expression of SIRT7 was higher in adipose tissues of obese patients than in the control group (VAT: P=0.001, SAT: P=0.008). The mean methylation of the SIRT1 and SIRT7 CpG islands was similar in tissues with high and low expression of these genes, and there was no correlation between the level of expression and the level of methylation. On the other hand, expression of SIRT1 in VAT of obese subjects correlated negatively with the expression of miR-22-3p (P<0.0001, r=-0.514), miR-34a-5p (P=0.01, r=-0.326) and miR-181a-3p (P<0.0001, r=-0.536). In turn, expression of SIRT7 in VAT of slim individuals correlated negatively with the expression of miR-125a-5p (P=0.003, r=-0.562) and miR-125b-5p (P=0.018, r=-0.460).
We observed obesity-associated downregulation of SIRT1 and upregulation of SIRT7 mRNA levels that were not associated with the methylation status of their promoters. We found a negative correlation between mRNA levels of SIRT1 in VAT of obese individuals and SIRT7 in VAT of the normal-weight subjects and expression of the relevant miRNAs.
背景/目的：鉴于其在代谢调节中的重要性，沉默调节蛋白（SIRTs）成为肥胖症和代谢综合征发病机制研究中颇具前景的研究对象。本研究旨在评估人类肥胖是否与脂肪组织中SIRT基因表达的变化相关，以及表观遗传机制，即DNA甲基化和微小RNA（miRNA）干扰，是否介导了这一现象。
对象/方法：通过实时PCR评估58名肥胖者（体重指数（BMI）>40 kg/m²）和31名正常体重者（BMI 20 - 24.9 kg/m²）的内脏脂肪组织（VAT）和皮下脂肪组织（SAT）中SIRTs以及与SIRT1和SIRT7 mRNA相互作用的miRNAs的表达。采用甲基化敏感酶切/实时PCR方法研究SIRTs的甲基化状态。
肥胖患者脂肪组织中SIRT1 mRNA水平低于正常体重对照组（VAT：P = 0.0002，SAT：P = 0.008）。相反，肥胖患者脂肪组织中SIRT7的表达高于对照组（VAT：P = 0.001，SAT：P = 0.008）。SIRT1和SIRT7 CpG岛的平均甲基化在这些基因高表达和低表达的组织中相似，且表达水平与甲基化水平之间无相关性。另一方面，肥胖受试者VAT中SIRT1的表达与miR - 22 - 3p（P < 0.0001，r = -0.514）、miR - 34a - 5p（P = 0.01，r = -0.326）和miR - 181a - 3p（P < 0.0001，r = -0.536）的表达呈负相关。相应地，苗条个体VAT中SIRT7的表达与miR - 125a - 5p（P = 0.003，r = -0.562）和miR - 125b - 5p（P = 0.018，r = -0.460）的表达呈负相关。
我们观察到肥胖相关的SIRT1下调和SIRT7 mRNA水平上调，且这与它们启动子的甲基化状态无关。我们发现肥胖个体VAT中SIRT1的mRNA水平与正常体重个体VAT中SIRT7的mRNA水平以及相关miRNAs的表达之间存在负相关。
