Metzler B, Hu Y, Sturm G, Wick G, Xu Q
Institute for Biomedical Aging Research, Austrian Academy of Sciences, A-6020 Innsbruck, Austria.
J Biol Chem. 1998 Dec 11;273(50):33320-6. doi: 10.1074/jbc.273.50.33320.
Arachidonic acid (AA) and its metabolites play important roles in a variety of biological processes, such as signal transduction, contraction, chemotaxis, and cell proliferation and differentiation. It was demonstrated recently that AA can activate mitogen-activated protein kinases (MAPKs), which are crucial for transducing signals initiating cell growth and apoptosis. Here we studied the effect of AA on the induction of MAPK phosphatase-1 (MKP-1) in vascular smooth muscle cells (VSMCs) and found that AA stimulated induction of MKP-1 mRNA and proteins in VSMCs in a time- and dose-dependent manner. Specific inhibitors of cyclooxygenase-, lipoxygenase-, and cytochrome P450-dependent metabolism did not affect AA-induced MKP-1 expression, indicating that eicosanoid biosynthesis was not involved in this process. The glutathione precursor N-acetylcysteine, an antioxidant, abolished AA-stimulated MKP-1 gene expression, whereas inhibition of protein kinase C by calphostin C had no influence on MKP-1 induction. VSMC pretreatment with genistein, a tyrosine kinase inhibitor, completely blocked AA-stimulated MKP-1 induction. MAPK kinase inhibitor PD 98059 did abolish AA-stimulated activation of extracellular signal-regulated kinases but not MKP-1 induction. Furthermore, agonists that increase AA release stimulated MKP-1 induction and activation of MAPKs, including extracellular signal-regulated kinases and c-Jun NH2-terminal protein kinases or stress-activated protein kinases. Taken together, our findings demonstrate that AA induced MKP-1 expression in VSMCs via activation of tyrosine kinases involving AA-induced free radical generation, suggesting an important role for MKP-1 in the regulation of AA-initiated signal transduction in VSMCs.
花生四烯酸（AA）及其代谢产物在多种生物学过程中发挥重要作用，如信号转导、收缩、趋化性以及细胞增殖和分化。最近有研究表明，AA可激活丝裂原活化蛋白激酶（MAPK），而MAPK对于转导启动细胞生长和凋亡的信号至关重要。在此，我们研究了AA对血管平滑肌细胞（VSMC）中MAPK磷酸酶-1（MKP-1）诱导的影响，发现AA以时间和剂量依赖性方式刺激VSMC中MKP-1 mRNA和蛋白的诱导。环氧化酶、脂氧化酶和细胞色素P450依赖性代谢的特异性抑制剂不影响AA诱导的MKP-1表达，表明类花生酸生物合成不参与此过程。谷胱甘肽前体N-乙酰半胱氨酸（一种抗氧化剂）可消除AA刺激的MKP-1基因表达，而钙磷蛋白C对蛋白激酶C的抑制对MKP-1诱导无影响。用酪氨酸激酶抑制剂染料木黄酮对VSMC进行预处理可完全阻断AA刺激的MKP-1诱导。MAPK激酶抑制剂PD 98059确实可消除AA刺激的细胞外信号调节激酶的激活，但不能消除MKP-1诱导。此外，增加AA释放的激动剂可刺激MKP-1诱导以及MAPK的激活，包括细胞外信号调节激酶和c-Jun NH2末端蛋白激酶或应激激活蛋白激酶。综上所述，我们的研究结果表明，AA通过激活涉及AA诱导自由基生成的酪氨酸激酶诱导VSMC中MKP-1表达，提示MKP-1在VSMC中AA启动的信号转导调节中起重要作用。
