非诺贝特抑制心肌细胞肥大的信号转导途径

The Signal Pathway by Which Fenofibrate Inhibits Cardiomyocytes Hypertrophy

目的研究过氧化物酶体增殖物激活受体α(PPAR-α)对内皮素1诱导的心肌肥大的作用及其对蛋白激酶B/糖原合成酶激酶3β-活化T细胞核因子(Akt/GSK3β-NFATc4)信号通路的影响。方法培养新生SD大鼠的心肌细胞,构建PPAR-α-EGFPN3质粒并转染心肌细胞,采用[3H]亮氨酸掺入法、蛋白免疫印迹(Westernblot)技术、免疫荧光技术等方法,观察PPAR-α过表达对内皮素1诱导的心肌细胞蛋白质合成的作用以及PPAR-α过表达对内皮素1诱导的Akt/GSK3β磷酸化和NFATc4核移位的影响。结果PPAR-α过表达和PPAR-α激动剂非诺贝特显著抑制了内皮素1诱导的心肌肥大;PPAR-α过表达及PPAR-α过表达联用非诺贝特可以显著抑制内皮素1诱导的Akt/GSK3β磷酸化;PPAR-α过表达防止了内皮素1诱导的NFATc4由胞浆到胞核的移位。结论PPAR-α可能通过影响Akt/GSK3β-NFATc4信号通路来抑制内皮素1诱导的心肌肥大反应。

Objective To investigate the effects of peroxisome proliferator-activated receptor（PPAR）-α on Endothelin-1（ET-1） induced cardiomyoeyte hypertrophy and its intracellular signal pathway. Methods PPAR-α-EGFPN3 plasmid was constructed to investigate the effects of PPAR-α on ET-1-induced phosphorylation of Akt and GSK3/3 and nuclear translocation of NFATc4 in cultured neonatal rat cardiomyocytes .[^3H]-leucine incorporation assay was performed to examine protein synthesis of cardiomyocyte. Western-blot analysis was performed to investigate the effects of PPAR-activator and overexpression of PPAR-α on phosphorylation of protein kinase B （Akt） at Ser 473 and GSK3β at Ser 9,and the nuclear protein levels of NFATc4. Immunofluorescenee and confocal microscopic assay were used to evaluate the effects of overexpressed PPAR-α on the nuclear translocation of NFATc4. Results Overexpression of PPAR-α and PPAR-activator fenofibrate inhibited ET-1-induced leucine uptake in cardiomyocytes. Either PPAR-α-EGFPN3 or the combination of PPAR-α-EGFPN3 with fenofibrate markedly inhibited ET-1 stimulated phosphorylation of Akt at Ser 473 and GSK3β at Set 9. ET-1 stimulation markedly increased the translocation of NFATc4 from the cytoplasm to the nucleus. However, the nuclear expression of NFATc4 was inhibited by overexpressed PPAR-α. Conclusion Activation of PPAR-α interferes with the signaling pathway of ET-1-induced cardiomyocyte hypertrophy through negative regulation of nuclear translocation of NFATc4 and inhibition of the Akt/GSK3β pathway in cultured cardiomyocytes.