Hamaguchi Erika, Takamura Toshinari, Shimizu Akiko, Nagai Yukihiro
Department of Endocrinology and Metabolism, Kanazawa University Graduate School of Medical Science, 13-1 Takara-machi, Kanazawa, Ishikawa 920-8641, Japan.
J Pharmacol Exp Ther. 2003 Dec;307(3):987-94. doi: 10.1124/jpet.103.054346. Epub 2003 Oct 8.
Plasminogen activator inhibitor type 1 (PAI-1) plays a role in the development of atherosclerosis in diabetic patients. PAI-1 is produced by endothelial cells stimulated with various inflammatory cytokines, such as tumor necrosis factor (TNF)-alpha, which induces insulin resistance. In diabetic patients, troglitazone, a thiazolidinedione, can lower the concentration of PAI-1. We investigated the TNF-alpha-induced signaling pathway that leads to PAI-1 synthesis and the target step of troglitazone in this pathway. TNF-alpha induced PAI-1 mRNA expression and protein production in human umbilical vein endothelial cells (HUVECs). A specific inhibitor for p38 mitogen-activated protein kinase, 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole (SB 203580), and a protein kinase C inhibitor, calphostin C, had no inhibitory effects on TNF-alpha-induced PAI-1 secretion. A protein tyrosine kinase inhibitor, genistein, completely inhibited TNF-alpha-induced PAI-1 secretion, whereas an inhibitor of extracellular signal-regulated kinase (ERK) kinase, 2'-amino-3'-methoxyflavone (PD98059), and a nuclear factor-kappaB (NF-kappaB) inhibitor, emodin, partly inhibited TNF-alpha-induced PAI-1 secretion. Together, PD98059 and emodin completely inhibited TNF-alpha-induced PAI-1 secretion, suggesting that both NF-kappaB-dependent and NF-kappaB-independent pathways are involved in TNF-alpha-induced signal pathway to PAI-1 production and that the latter pathway is mediated by activation of ERK. Furthermore, we have shown that troglitazone inhibited both TNF-alpha-induced PAI-1 protein secretion and mRNA in HUVECs. Genistein, but neither PD98059 nor emodin, was additive to the inhibitory effect of troglitazone on TNF-alpha-induced PAI-1 secretion. These results indicate That ERK and NF-kappaB are possible targets of TNF-alpha and troglitazone in the regulation of PAI-1 production.
1型纤溶酶原激活物抑制剂（PAI-1）在糖尿病患者动脉粥样硬化的发展过程中发挥作用。PAI-1由受到多种炎性细胞因子刺激的内皮细胞产生，如可诱导胰岛素抵抗的肿瘤坏死因子（TNF）-α。在糖尿病患者中，噻唑烷二酮类药物曲格列酮可降低PAI-1的浓度。我们研究了导致PAI-1合成的TNF-α诱导信号通路以及曲格列酮在该通路中的作用靶点。TNF-α可诱导人脐静脉内皮细胞（HUVECs）中PAI-1 mRNA表达和蛋白质生成。p38丝裂原活化蛋白激酶特异性抑制剂4-（4-氟苯基）-2-（4-甲亚磺酰基苯基）-5-（4-吡啶基）-1H-咪唑（SB 203580）和蛋白激酶C抑制剂钙泊三醇对TNF-α诱导的PAI-1分泌无抑制作用。蛋白酪氨酸激酶抑制剂染料木黄酮可完全抑制TNF-α诱导的PAI-1分泌，而细胞外信号调节激酶（ERK）激酶抑制剂2'-氨基-3'-甲氧基黄酮（PD98059）和核因子-κB（NF-κB）抑制剂大黄素可部分抑制TNF-α诱导的PAI-1分泌。PD98059和大黄素共同作用可完全抑制TNF-α诱导的PAI-1分泌，这表明NF-κB依赖性和非依赖性途径均参与了TNF-α诱导的PAI-1产生信号通路，且后一途径由ERK激活介导。此外，我们还发现曲格列酮可抑制HUVECs中TNF-α诱导的PAI-1蛋白分泌和mRNA表达。染料木黄酮可增强曲格列酮对TNF-α诱导的PAI-1分泌的抑制作用，而PD98059和大黄素则无此作用。这些结果表明，ERK和NF-κB可能是TNF-α和曲格列酮在调节PAI-1产生过程中的作用靶点。
