同型半胱氨酸调控脂肪组织PDK1的表达与糖代谢的关系

Relationship between adipose expression of 3-phosphoinositide-dependent protein kinase 1 and glycometabolism in a mouse model of hyperhomocysteinemia

目的研究同型半胱氨酸对脂肪组织PDK1表达的影响,探讨PDK1是否抑制p-Ak(tThr-308),影响PI3K/Akt信号通路,降低脂肪组织对葡萄糖的摄取和利用。方法 40只6周龄小鼠(n=10只)随机分为:空腹正常对照组;进食正常对照组;空腹高同型半胱氨酸血症组和进食高同型半胱氨酸血症组。利用小鼠饮用水中加入1.5%的甲硫氨酸饲养3个月制作高同型半胱氨酸血症的动物模型。测定各组血糖和血胰岛素。利用RT-PCR检测PDK1和Akt的mRNA表达水平,Western blotting检测PDK1、p-Ak(tThr-308)和Akt的表达。结果与空腹和进食对照组相比,空腹和进食高同型半胱氨酸组小鼠血糖和血胰岛素的含量增加(P<0.05),PDK1的mRNA表达水平下调,PDK1、p-Ak(tThr-308)蛋白质表达降低(P<0.05),而Akt在mRNA和蛋白质的表达水平差异无统计学意义。结论在脂肪组织中,同型半胱氨酸可能通过调控PDK1表达的下调,影响PI3K/Akt信号通路,导致对葡萄糖的摄取能力降低。这可能是同型半胱氨酸引起糖代谢紊乱的原因之一。

Objective To study the effect of homcysteine on the expression of 3-phosphoinositide-dependent protein kinase 1（PDK1） in the adipose tissue and explore whether PDK1 inhibits p-Akt（Thr-308） expression and affect PI3K/Akt signal pathway to decrease glucose uptake and utilization.Methods Forty mice were randomly divided into 4 groups（n=10）,namely the fasting control group,feeding control group,fasting hyperhomocysteinemia group,and feeding hyperhomocysteinemia group.In the two hyperhomocysteinemia groups,the mice were given water containing 1.5% methionine to induce hyperhomocysteinemia.Blood glucose and insulin levels in each group were determined,and the expressions of PDK1 and Akt mRNA in the adipose tissue were detected using RT-PCR;the expressions of PDK1,p-Akt（Thr-308） and Akt proteins were detected using Western blotting.Results In the fasting and feeding hyperhomocysteimia groups,blood glucose and insulin levels were significantly higher than those in the two control groups.The expressions of PDK1 mRNA and PDK1 and p-Akt（Thr-308） proteins were reduced in the two hyperhomocysteimia groups,but Akt mRNA and protein expressions were comparable with those in the control groups.Conclusion Homocysteine lowers the uptake and utilization of glucose by down-regulating PDK1 expression and affecting PI3K/Akt signal pathway to cause disturbance of glucose metabolism.