Ito H, Hirata Y, Hiroe M, Tsujino M, Adachi S, Takamoto T, Nitta M, Taniguchi K, Marumo F
Second Department of Medicine, Tokyo Medical and Dental University, Japan.
Circ Res. 1991 Jul;69(1):209-15. doi: 10.1161/01.res.69.1.209.
To determine whether endothelin-1 (ET-1) induces hypertrophy of cardiomyocytes, the effects of ET-1 on the expression of muscle-specific genes and a proto-oncogene, c-fos, in cultured neonatal rat cardiomyocytes were examined by Northern blot analysis. ET-1 (10(-7) M) induced about twofold to fourfold increases in the gene expression of myosin light chain 2, alpha-actin, and troponin I after 6 hours, which continued up to 24 hours. The ET-1-induced increases in mRNA levels for these muscle-specific genes were dose dependent (10(-9) to 10(-7) M). Run-on transcriptional assay showed that the changes in mRNA level for three muscle-specific genes were regulated, at least in part, at the transcriptional level. 12-O-Tetradecanoylphorbol 13-acetate (TPA), a potent protein kinase C activator, and the Ca2+ ionophore ionomycin also increased mRNA levels of three muscle-specific genes. ET-1, TPA, and ionomycin similarly induced the expression of c-fos after 30 minutes, which returned to an undetectable level after 6 hours. ET-1 remarkably and dose-dependently stimulated accumulation of total inositol phosphates in cardiomyocytes. Morphometrical evaluation showed that ET-1 significantly increased surface area of cardiomyocytes without cell proliferation. ET-1 also dose-dependently stimulated the synthesis of protein and DNA, which was unaffected by the L-type calcium channel blocker nicardipine. These data suggest that ET-1 induces hypertrophy of cardiomyocytes associated with the induction of muscle-specific gene transcripts through the possible involvement of protein kinase C activation or intracellular Ca2+ mobilization.
为了确定内皮素 -1（ET -1）是否会诱导心肌细胞肥大，通过Northern印迹分析检测了ET -1对培养的新生大鼠心肌细胞中肌肉特异性基因和原癌基因c - fos表达的影响。ET -1（10^(-7) M）在6小时后使肌球蛋白轻链2、α - 肌动蛋白和肌钙蛋白I的基因表达增加了约两倍至四倍，并持续至24小时。ET -1诱导的这些肌肉特异性基因mRNA水平的增加呈剂量依赖性（10^(-9)至10^(-7) M）。核转录分析表明，三种肌肉特异性基因mRNA水平的变化至少部分是在转录水平上受到调控的。12 - O - 十四酰佛波醇13 - 乙酸酯（TPA），一种有效的蛋白激酶C激活剂，以及Ca2+离子载体离子霉素也增加了三种肌肉特异性基因的mRNA水平。ET -1、TPA和离子霉素在30分钟后同样诱导了c - fos的表达，6小时后恢复到不可检测的水平。ET -1显著且剂量依赖性地刺激心肌细胞中总肌醇磷酸的积累。形态学评估显示，ET -1显著增加了心肌细胞的表面积但无细胞增殖。ET -1还剂量依赖性地刺激了蛋白质和DNA的合成，而这不受L型钙通道阻滞剂尼卡地平的影响。这些数据表明，ET -1通过可能涉及的蛋白激酶C激活或细胞内Ca2+动员诱导与肌肉特异性基因转录本诱导相关的心肌细胞肥大。
