激活的Akt对心肌细胞的增殖调控

Cell cycle regulation of activated Akt in cardiomyocytes

目的通过检测Akt在大鼠心肌细胞退出细胞周期过程中的表达及Akt表达载体转染后大鼠心肌细胞有丝分裂的改变,探讨Akt对心肌细胞增殖的影响。方法生后不同发育阶段和成年健康Wistar大鼠各5只,用RT-PCR和免疫印迹法,检测心肌组织Akt的mRNA和蛋白磷酸化水平改变;培养大鼠H9c2(2-1)心肌细胞,通过胰岛素刺激和真核表达载体pCIS2-Akt-WT转染两种方式激活细胞内Akt,采用免疫沉淀方法检测细胞内磷酸化组蛋白H3表达改变,观察Akt对心肌细胞有丝分裂的影响。结果大鼠生后7d到2周心肌组织Akt mRNA表达和蛋白磷酸化水平明显下降(P<0.01),激活的Akt促使大鼠H9c2(2-1)心肌细胞磷酸化组蛋白H3表达显著增加(P<0.01)。结论 Akt能促进可增殖心肌细胞的有丝分裂。

Objective In order to study the effect of Akt on cardiomyocytes proliferation, the expression of Akt during postnatal development of rat heart was detected and the change of mitosis was examined after Akt was activated on cardiomyocytes. Methods The mRNA expression of Akt and the phosphorylation level of Akt protein during the postnatal developmental process （five cases per groups） were detected by RT-PCR and Western blotting analysis in rat hearts. H9c2 （2-1） cardiomyocytes were originally isolated and cultured from rat BDIX heart. The Akt was activated by insulin stimulation and/or pCIS2-Akt-WT plasmid transfection. After that the expression of phospho-histone H3 （H3P） protein was detected by immunoprecipitation analysis on H9c2（2-1 ） cardiomyoeytes. Results The mRNA expression of Akt and the phosphorylation level of Akt protein were down-regulated significantly （ P 〈 0. 01 ） during postnatal 0-day-old group to 2- week-old group of rat heart. Actived Akt increased markedly the expression of H3P protein on H9c2（2-1 ） eardiomyocytes （P 〈 0.01 ）. Conclusion Akt can promote mitosis of reproductive cardiomyocytes.