心肌营养素-1诱导大鼠心肌细胞肥大与JAK激酶/信号转导转录活化因子信号通路的关系

Cardiotrophin-1 Induce Hypertrophic Response in Rat Cardiac Myocytes by JAK-STAT Signal Pathway

目的研究心肌营养素1(CT1)对培养大鼠心肌细胞肥大的诱导作用,探讨细胞因子信号途径JAK激酶/信号转导转录活化因子(JAKSTAT)与CT1诱导心肌细胞肥大的关系。方法以培养的新生SpragueDawley(SD)大鼠心肌细胞为实验模型,分为对照组、CT1刺激组(10ng/mL)、JAK2拮抗剂AG490(10μmol/L)干预组。应用图像分析系统测定心肌细胞表面积,[3H]亮氨酸掺入法测定心肌细胞蛋白合成速率,逆转录聚合酶链式反应(RTPCR)检测心钠素(ANP)mRNA表达,RTPCR和蛋白免疫印迹法(Westernblot)检测JAKSTAT的mRNA和蛋白表达水平。结果(1)CT1组心肌细胞表面积(1664.7±152.3)μm2明显高于对照组(621.1±90.2)μm2,P<0.01,AG490干预后心肌细胞面积(862.9±158.1)μm2明显减小,与CT1组比较,P<0.01。(2)CT1组心肌细胞[3H]亮氨酸掺入率(2388±72)计数/(min·孔)高于对照组(1353±81)计数/(min·孔),P<0.01,AG490组[3H]亮氨酸掺入率(1693±59)计数/(min·孔)明显下降,与CT1组比较,P<0.01。(3)CT1组心肌细胞ANP的mRNA表达水平(0.61±0.03)明显增强,与对照组(0.23±0.02)比较,P<0.01,经AG490干预后ANP的mRNA表达水平(0.29±0.02)明显下降,和CT1组相比,P<0.01。(4)CT1刺激后心肌细胞JAKSTAT的mRNA和蛋白表达水平显著增强(P<0.01),在AG490干预后JAKSTAT的mRNA和蛋白表达明显减弱,与CT1组比较,P<0.05。结论CT1有明显的促心肌细胞肥大效应,细胞因子信号通路JAKSTAT活化参与了这一过程,并可能是心肌细胞肥大的分子生物学机制之一。

Objective To investigate the effects of cardiotrophin-1（CT-1） on cultured rat cardiomyocytes, and whether the Janus activated kinase/signal transducer activator of transcription （JAK/STAT） signal pathway is involved in myocytes hypertrophy induced by CT-1. Methods Sprague-Dawley （SD） neonatal rat cardiac myocytes, partly pretreated with AG490 （an inhibitor of JAK2 ） were cultured with or without CT-1（10 ng/mL）. Image analysis system, [^3H]-leucine incorporation, RT-PCR and Western blot were used to measure the cell surface area, protein synthesis, expression of mRNA of atrial natriuretic peptide（ANP）and JAK-STAT, and the expression of JAK-STAT protein in cardiomyocytes respectively. Results （ 1）Cardiac myocytes surface areas were greater in CT-1 group than that in control group（ 1664. 7 ± 152.3 vs 621.1 ± 90.2 μm^2 , P〈0, 01 ）, AG490 substantially inhibited the increase of CT-1 induced cardiac myocytes surface area（P〈0. 01 ）;（ 2 ）Incorporation rate of [^3H]-leucine in myocytes in CT-1 group was much higher than that in control group（ 2388± 72 vs 1353 ± 81 cpm/well, P〈 0, 01 ）, which was significantly inhibited by AG490 （P〈0. 01 ）;（3）The ANP mRNA expression level in myocytes in CT-1 group increased significantly （ 0. 6 1 ± 0, 0 3 vs control ： 0. 2 3 ± 0. 0 2, P 〈 0.0 1 ） , which was inhibited by AG490（ P〈0. 01 ）. （ 4 ） The increased expression of JAK-STAT mRNA and protein by CT-1 was also inhibited by AG490 （P〈0. 01 ）. Conclusion A strong hypertropic action induced by cardiotrophin-1 was found in cultured cardiomyocytes which is likely activated by JAK-STAT signal pathway.