Ohara Y, Sayegh H S, Yamin J J, Harrison D G
Division of Cardiology, Emory University School of Medicine, Atlanta, GA 30322.
Hypertension. 1995 Mar;25(3):415-20. doi: 10.1161/01.hyp.25.3.415.
Protein kinase C (PKC) plays a key role in a variety of signal transduction processes. The promoter region of the endothelial constitutive nitric oxide synthase (ecNOS) gene contains a transcriptional factor AP-1 binding element. In the present study, we sought to determine the effect of PKC inhibition on the expression of ecNOS in cultured bovine aortic endothelial cells (BAEC). The PKC inhibitor staurosporine (10 to 100 nmol/L) increased the expression of ecNOS mRNA, assessed by Northern analysis, in a dose-dependent manner. A newly developed, more specific PKC inhibitor, chelerythrine (1 to 3 mumol/L), also increased the level of ecNOS mRNA. Incubation of BAEC with phorbol 12-myristate 13-acetate (100 nmol/L) for 24 hours, which downregulates PKC, increased ecNOS mRNA expression. The protein content of ecNOS, assessed by Western analysis, was also increased in staurosporine-treated or chelerythrine-treated BAEC. The release of nitrogen oxides from staurosporine-treated or chelerythrine-treated cells both under basal conditions and in response to calcium ionophore A23187 was significantly increased (P < .05). In conclusion, the present study suggests that regulation of ecNOS is mediated by PKC. The increased release of nitric oxide induced by PKC inhibition may play a protective role against atherogenic process.
蛋白激酶C（PKC）在多种信号转导过程中起关键作用。内皮型一氧化氮合酶（ecNOS）基因的启动子区域含有一个转录因子AP-1结合元件。在本研究中，我们试图确定PKC抑制对培养的牛主动脉内皮细胞（BAEC）中ecNOS表达的影响。通过Northern分析评估，PKC抑制剂星形孢菌素（10至100 nmol/L）以剂量依赖性方式增加了ecNOS mRNA的表达。一种新开发的、更具特异性的PKC抑制剂白屈菜红碱（1至3 μmol/L）也增加了ecNOS mRNA的水平。用佛波醇12-肉豆蔻酸酯13-乙酸酯（100 nmol/L）孵育BAEC 24小时可下调PKC，增加ecNOS mRNA表达。通过Western分析评估，在经星形孢菌素处理或白屈菜红碱处理的BAEC中，ecNOS的蛋白含量也增加。在基础条件下以及对钙离子载体A23187作出反应时，经星形孢菌素处理或白屈菜红碱处理的细胞中氮氧化物的释放均显著增加（P <.05）。总之，本研究表明ecNOS的调节由PKC介导。PKC抑制诱导的一氧化氮释放增加可能对动脉粥样硬化形成过程起保护作用。
