【摘要】 目的:研究过氧化物酶体增殖物激活受体-α(PPAR-α)在病理性心肌肥大中的作用及其信号机制。方法:应用Invitrogen’s Stealth RNAi抑制心肌细胞PPAR-α的表达;采用[3H]-亮氨酸掺入法和RT-PCR检查心肌细胞蛋白质合成和心房利钠因子(ANF)mRNA的表达;采用Western blotting法检测Akt/GSK3β的磷酸化表达;应用免疫荧光技术检测NFATc4的胞核移位。结果:(1)RSS304168是最有效的PPAR-αRNAi,特异性地抑制了PPAR-α的表达。(2)非诺贝特预处理抑制了内皮素-1(ET-1)诱导的心肌细胞肥大(蛋白质合成和ANF mRNA的表达);RSS304168加强了ET-1的诱导效应,而且逆转了非诺贝特对心肌肥大的抑制效应。(3)非诺贝特降低了ET-1诱导的Akt/GSK3β的磷酸化表达,RSS304168增强了ET-1的诱导效应,ET-1和RSS304168的上述作用可被PI3K阻断剂LY294002所阻断;RSS304168逆转了非诺贝特对Akt/GSK3β的磷酸化表达的负性调控作用。(4)非诺贝特抑制了ET-1诱导的NFATc4的胞核移位;而RSS304168加强了ET-1的诱导作用,逆转了非诺贝特对NFATc4胞核移位的抑制作用。结论:PPAR-α激活可以通过PI3K/Akt/GSK3β-NFATc4通路抑制ET-1诱导的心肌肥大反应。更多还原

【Abstract】 AIM:To investigate the role and signal mechanism of PPAR-α in the pathogenesis of cardiac hypertrophy. METHODS:Small interfering RNA (siRNA) was applied to efficiently silence the gene expression of PPAR-α in cardiac myocytes. [3H] leucine incorporation assay was performed to measure protein synthesis. Reverse transcription-polymerase chain reaction (RT-PCR) was used to analyze the mRNA level of atrial natriuretic factor (ANF) and PPAR-α. Western blotting analysis was performed to investigate the levels of phosphorylation of protein kinase B (PKB/Akt) and glycogen synthase kinase 3β (GSK3β). Immunofluorescence analysis was used to examine the cellular localization of NFATc4. RESULTS:(1)RSS304168 was the most efficient stealth RNAi duplex to specifically inhibit PPAR-α expression. (2)RSS304168 significantly potentiated the ET-1-induced cardiomyocyte hypertrophy and enhanced ET-1-induced protein synthesis and ANF mRNA expression in cardiomyocytes. Moreover,RSS304168 completely reversed the inhibitory effects of fenofibrate on ET-1-induced protein synthesis and ANF mRNA expression. (3)RSS304168 enhanced ET-1-induced phosphorylation of Akt at Ser473 and GSK3β at Ser9. The effects of ET-1 or ET-1 combined with RSS304168 on phosphorylation of Akt/GSK3β were completely blocked by LY294002,a PI3K specific inhibitor. Fenofibrate markedly inhibited ET-1-induced phosphorylation of Akt/GSK3β while RSS304168 abolished these effects of fenofibrate. (4)Fenofibrate prevented the nuclear translocation of NFATc4 induced by ET-1 while RSS304168 abolished this effect of fenofibrate. CONCLUSION:Activation of PPAR-α inhibits ET-1-induced cardiomyocyte hypertrophy through blocking Akt/GSK3β-NFATc4 signaling pathways.更多还原