磷脂酰肌醇3激酶调节亚基P85α在自发性糖尿病大鼠心肌中表达下降

Decreased expression of p85α in myocardium of spontaneous diabetes rats

目的探讨糖尿病晚期心肌病变的细胞分子机制。方法分别选用Otsuka Long-EvansTokushima Fatty(OLETF)和Long-Evans Tokushima Otsuka(LETO)大鼠作为实验组和对照组。基因芯片、实时定量PCR、Western blot法比较两组大鼠心肌磷脂酰肌醇3激酶(PI3K)调节亚基P85α的表达。结果与LETO大鼠相比,OLETF大鼠血浆Ins下降(6.0±2.9 vs 52.6±7.5 mU/L,P<0.01),TG和TC增加(1.73±0.34 vs 0.48±0.08 mmol/L,P<0.01;4.41±0.21 vs 2.25±0.75 mmol/L,P<0.01),左心室内压舒张期下降速率(—dp/dt)降低30%(P<0.05)。基因芯片检测显示,OLETF大鼠心肌组织中P85α基因表达量仅为LETO大鼠的1/8。实时定量PCR和Western blot证实OLETF大鼠P85α基因在转录和翻译水平分别较LETO大鼠下降了81.5%(P<0.05)和43.2%(P<0.01)。结论自发性糖尿病大鼠OLETF心肌组织P85α mRNA和蛋白表达水平显著下降与心肌收缩、舒张速率下降相关。

Objective To study the molecular and cellular mechanism of cardiomyopathy in long- term diabetes. Methods OLETF rats and LETO rats were used as experimental and control group respectively. Gene chip, real-time PCR, Western blot analysis were applied to show the different expressions of P85a between OLETF and LETO rats. Results As compared with LETO rats, the concentrations of average plasma insulin in OLETF rats was lower （6.0 ± 2.9 vs 52.6 ± 7.5 mU/L, P〈 0. 01）, the triglyeeride and cholesterol level were higher（1. 73±0. 34 vs 0. 48±0. 08 mmol/L, P〈0. 01 ; 4.41 ±0. 21 vs 2.25±0.75 retool/L, P〈0. 01） ,and the velocity of left ventrieular diastole of OLETF rats decreased by 30%（P〈0. 05）. The result of microarray assays indicated an 8-fold fall-off in the expression of p85α mRNA in myoeardium of OLEFT rats. The real-time PCR assay and Western blot analysis provided further support that the gene transcription and protein expression levels of p85α were decreased by 81.5% and 43.2% respeetively（P〈0. 05 and P〈0. 001）. Conclusions The reductions of gene transcription and protein expression of p85α in myocardium of OLETF rats are related to impaired construction and functions.