食源性肥胖大鼠下丘脑Tsc1启动子区甲基化率、mTOR表达变化

目的 观察食源性肥胖大鼠下丘脑结节性硬化症基因1(tuberous sclerosis complex 1,Tsc1)启动子区甲基化率及哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,mTOR)的表达.方法 16只雄性SD大鼠分为高脂喂养组和基础饲料喂养组(对照组),每组8只,共喂养12周.测定两组大鼠体质量、腹腔脂肪量、腹腔脂肪/体质量比值,采用重亚硫酸盐的测序法检测Tsc1启动子甲基化,RT-PCR、Western blot分别检测mTORmRNA和蛋白表达.结果 高脂组大鼠体质量、腹腔脂肪量、腹腔脂肪/体质量比均高于对照组(P＜0.05).两组大鼠下丘脑Tsc1启动子区均有11个位点可被甲基化,食源性肥胖组甲基化率(94.50％±4.66％)高于对照组(86.60％±3.49％,P＜0.002),mTOR mRNA和蛋白表达均高于对照组(P＜0.05).结论 食源性肥胖大鼠下丘脑Tsc1基因启动子甲基化率增加,其下游基因mTOR表达上调,可能参与了肥胖的发生.

Tsc1 Promoter Methylation Rate, mTOR Expression in Food-induced Obese Rat Hypothalamus

Objective To investigate the methylation rate of tuberous sclerosis complex 1 (Tsc1) promoter and expression of mammalian target of rapamycin (mTOR) in food-induced rat hypothalamus. Methods 16 male SD rats were divided into high fat diet induced group (8 rats) and normal control group (8 rats) feeding for 12 weeks. Body mass, mass of celiac fat, celiac fat/body mass were measured. Methylation of Tsc1 promoter, mRNA and protein expression of mTOR were detected by bisulfite sequencing method, RT-PCR and Western blot, respectively. Results Mass of celiac fat, celiac fat/body mass were higher in food-induced rat than that in control group. There were 11 methylation sites in SD rat hypothalamus. Obese group has significantly higher methylation rates (94.50%±4.66%) than that of control group (86.60%±3.49%) (P <0.002). The mRNA and protein expression of mTOR were noted lower in control group than in obese group (P <0.05). Conclusion The increased methylation rate of Tsc1promoter in food-induced rat hypothalamus and up-regulated expression of mTOR, downstream gene of Tsc1may promote the obesity.