Activation of MAPK by modified low-density lipoproteins in vascular smooth muscle cells.
Activation of MAPK by modified low-density lipoproteins in vascular smooth muscle cells.
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血管平滑肌细胞中修饰的低密度脂蛋白激活 MAPK。
DOI：
10.1152/jappl.2001.91.3.1412
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Jaffa,AA
中科院分区：
文献类型：
--
作者：
Velarde,V;Jenkins,AJ;Christopher,J;Lyons,TJ;Jaffa,AA
循环中高浓度的低密度脂蛋白(LDL)是动脉粥样硬化的主要危险因素。糖尿病患者体内天然低密度脂蛋白和经糖基化和/或氧化修饰的低密度脂蛋白增加。低密度脂蛋白直接刺激血管平滑肌细胞(VSMC)增殖，但其作用机制尚不清楚。细胞外信号调节激酶(ERK)通路介导细胞功能和生长的变化。因此，我们检测了天然和修饰的低密度脂蛋白对VSMC中ERK磷酸化的影响。加入天然、轻度修饰(氧化、糖化、糖化)和高度修饰(高度氧化、高度氧化)的低密度脂蛋白(25μg/ml)作用5min，可使ERK的磷酸化增加5倍。为了阐明低密度脂蛋白磷酸化ERK的信号转导途径，我们研究了钙/钙调蛋白途径、蛋白激酶C(PKC)、src激酶和丝裂原活化蛋白激酶(MEK)的作用。细胞内钙离子螯合剂EGTA-AM(50mmol.L o l/L)显著增加天然和轻度修饰的低密度脂蛋白诱导的细胞外钙通道的磷酸化，而细胞外钙离子的螯合作用(3μ/L)显著降低低密度脂蛋白诱导的ERK磷酸化。钙调素inhibitorN-(6-aminohexyl)-1-naphthalenesulfonamide(40μ/L)可显著降低各种低密度脂蛋白诱导的ERK磷酸化。佛波醇肉豆蔻酸醋酸酯(5μ/L)下调蛋白激酶C的表达可显著降低低密度脂蛋白诱导的ERK的磷酸化。细胞通透性的蛋白酪氨酸激酶抑制剂(PD-98059，40μ/L)可显著降低天然和修饰的低密度脂蛋白诱导的细胞外信号调节蛋白激酶的磷酸化。这些发现表明，天然和轻度和高度修饰的低密度脂蛋白利用相似的信号通路来磷酸化ERK，并涉及到钙/钙调蛋白、PKC和MEK的作用。这些结果表明，修饰的低密度脂蛋白、血管功能和糖尿病动脉粥样硬化的发展之间存在潜在的联系。
A high concentration of circulating low-density lipoproteins (LDL) is a major risk factor for atherosclerosis. Native LDL and LDL modified by glycation and/or oxidation are increased in diabetic individuals. LDL directly stimulate vascular smooth muscle cell (VSMC) proliferation; however, the mechanisms remain undefined. The extracellular signal-regulated kinase (ERK) pathway mediates changes in cell function and growth. Therefore, we examined the cellular effects of native and modified LDL on ERK phosphorylation in VSMC. Addition of native, mildly modified (oxidized, glycated, glycoxidized) and highly modified (highly oxidized, highly glycoxidized) LDL at 25 μg/ml to rat VSMC for 5 min induced a fivefold increase in ERK phosphorylation. To elucidate the signal transduction pathway by which LDL phosphorylate ERK, we examined the roles of the Ca2+/calmodulin pathway, protein kinase C (PKC), src kinase, and mitogen-activated protein kinase kinase (MEK). Treatment of VSMC with the intracellular Ca2+chelator EGTA-AM (50 μmol/l) significantly increased ERK phosphorylation induced by native and mildly modified LDL, whereas chelation of extracellular Ca2+by EGTA (3 mmol/l) significantly reduced LDL-induced ERK phosphorylation. The calmodulin inhibitorN-(6-aminohexyl)-1-naphthalenesulfonamide (40 μmol/l) significantly decreased ERK phosphorylation induced by all types of LDL. Downregulation of PKC with phorbol myristate acetate (5 μmol/l) markedly reduced LDL-induced ERK phosphorylation. Pretreatment of VSMC with a cell-permeable MEK inhibitor (PD-98059, 40 μmol/l) significantly decreased ERK phosphorylation in response to native and modified LDL. These findings indicate that native and mildly and highly modified LDL utilize similar signaling pathways to phosphorylate ERK and implicate a role for Ca2+/calmodulin, PKC, and MEK. These results suggest a potential link between modified LDL, vascular function, and the development of atherosclerosis in diabetes.