PTEN抑制钙/钙调神经磷酸酶信号通路、负性调控血管紧张素Ⅱ所致心肌细胞肥大

目的 观察PTEN过度表达对血管紧张素Ⅱ（AngⅡ）刺激所致钙／钙调神经磷酸酶（Ca^2＋／CaN）信号通路激活的影响,探讨PTEN负性调控心肌肥厚的作用机制。方法通过携带野生型PTEN基因的腺病毒（Ad-PTEN）感染构建过度表达PTEN的原代培养心肌细胞模型,用AngⅡ作为促心肌肥厚刺激剂,Fura-2／AM比率荧光成像系统检测细胞内Ca^2＋浓度（Ca^2＋]i）,逆转录聚合酶链反应检测受感染细胞内心房利钠因子（ANF）、β-肌球蛋白重链（B-MHC）与CaNAβ的mRNA表达,Western blot检测CaNAβ的蛋白表达,同时测定CaN活性。结果 Ad-PTEN感染后,心肌细胞内过度表达PTEN的mRNA和蛋白。PTEN的过度表达能够明显抑制AngⅡ刺激所致的心肌细胞肥大标志基因表达。AngⅡ刺激使Ca^2＋]i、CaNAβ mRNA与蛋白表达以及CaN活性明显增高,PTEN过度表达能够明显抑制AngⅡ引起的Ca^2＋]i、CaNAβ mRNA与蛋白表达以及CaN活性增高。结论 PTEN过度表达可能通过抑制Ca^2＋／CaN信号通路,负性调控AngⅡ刺激所致的心肌细胞肥大。

Angiotensin II induced cardiac hypertrophy is blocked by PTEN via suppressing Ca2+/Calcineurin pathway

OBJECTIVE: To investigate the effects of PTEN on Ang II induced cardiomyocyte hypertrophy and subsequent Ca(2+)/Calcineurin pathway changes. METHODS: Primary cultured neonatal rat cardiomyocytes were cultured and were treated with phosphate-buffered saline, empty adenovirus (Ad-GFP), or adenovirus encoding for PTEN (Ad-PTEN-GFP) for 48 h and Ang II (10(-7) mol/L) was added to the medium for another 24 h. Cells were harvested and intracellular Ca(2+) concentration (Ca(2+)] i) was determined by Fura-2/AM ratio imaging analysis; PTEN, ANF, beta-MHC and CaNAbeta mRNA evaluated with RT-PCR; PTEN and CaNAbeta protein by Western blot; CaN phosphatase activity by CaN detecting kits. RESULTS: PTEN at mRNA and protein levels were significantly higher in Ad-PTEN-GFP treated cardiomyocytes than that of Ad-GFP treated cardiomyocytes. Ang II stimulation upregulated Ca(2+)] i, CaNAbeta at mRNA and protein levels and CaN phosphatase activity in Ad-GFP treated cardiomyocytes but not in Ad-PTEN-GFP treated cardiomyocytes. CONCLUSIONS: Cardiac hypertrophy induced by Ang II could be blocked by PTEN overexpression via suppressing Ca(2+)/Calcineurin pathway.