Coroneos E J, Kester M, Maclouf J, Thomas P, Dunn M J
Department of Medicine, Houston Veterans Affairs Medical Center, Baylor College of Medicine, USA.
J Am Soc Nephrol. 1997 Jul;8(7):1080-90. doi: 10.1681/ASN.V871080.
The role of endothelin (ET)-1-mediated cytosolic calcium ([Ca2+]i) elevation in regulating ET-1-induced prostaglandin endoperoxide synthase, prostaglandin G/H synthase (PGHS)-2 mRNA expression and protein synthesis was investigated in mesangial cells (MC). Ionomycin, a calcium ionophore, and thapsigargin, an inhibitor of calcium ATPase, mimicked the ET-1-stimulated PGHS-2 mRNA and protein induction. Inhibition of [Ca2+]i increases with (2-¿C2-bis-(carboxymethyl)-amino-5 methylphenoxy]methyl¿-6-methoxy-8-bis-(carboxymethyl)-aminoquinoline tetra-(acetoxymethyl)ester (Quin/AM), a calcium chelator, or with the combined presence of [8-(diethylamino)-octyl-3,4,5-trimethoxybenzoate, HCl] (TMB), an inhibitor of intracellular calcium stores release, and ethyleneglycol-bis-(beta-aminoethyl)- N,N,N',N'-tetra-acetic acid (EGTA) suppressed ET-1, as well as ionomycin and thapsigargin-mediated PGHS-2 mRNA and protein formation. Also, the ET-1-, ionomycin-, and thapsigargin-induced PGHS-2 mRNA expression and protein formation was inhibited in MC pretreated with inhibitors of calcium calmodulin kinase. In contrast, these conditions did not inhibit interleukin (IL)-1-induced PGHS-2 mRNA expression and protein synthesis. Pretreatment with tyrosine kinase inhibitors abolished the ET-1-, ionomycin-, thapsigargin-, and IL-1-mediated PGHS-2 mRNA and protein induction. ET-1-, ionomycin-, and thapsigargin- induced protein tyrosine phosphorylation, but not IL-1-induced protein tyrosine phosphorylation, was suppressed by inhibiting either [Ca2+]i elevation or calcium calmodulin kinase activation. It was concluded that elevation of [Ca2+]i and activation of calcium calmodulin kinases are upstream mediators of ET-1-induced PGHS-2 gene expression through activation of non-receptor-linked protein tyrosine kinase in MC.
研究了内皮素（ET）-1介导的细胞溶质钙（[Ca2+]i）升高在调节ET-1诱导的前列腺素内过氧化物合酶、前列腺素G/H合酶（PGHS）-2 mRNA表达和蛋白质合成中的作用，研究对象为系膜细胞（MC）。离子霉素（一种钙离子载体）和毒胡萝卜素（一种钙ATP酶抑制剂）模拟了ET-1刺激的PGHS-2 mRNA和蛋白质诱导作用。用钙螯合剂[2-（2-双（羧甲基）氨基-5-甲基苯氧基）甲基]-6-甲氧基-8-双（羧甲基）氨基喹啉四（乙酰氧基甲基）酯（Quin/AM）或同时存在细胞内钙库释放抑制剂[8-（二乙氨基）辛基-3,4,5-三甲氧基苯甲酸，HCl]（TMB）和乙二醇双（β-氨基乙基）-N，N，N'，N'-四乙酸（EGTA）抑制[Ca2+]i升高，可抑制ET-1以及离子霉素和毒胡萝卜素介导的PGHS-2 mRNA和蛋白质形成。此外, 用钙调蛋白激酶抑制剂预处理的MC中，ET-1、离子霉素和毒胡萝卜素诱导的PGHS-2 mRNA表达和蛋白质形成受到抑制。相反，这些条件并未抑制白细胞介素（IL）-1诱导的PGHS-2 mRNA表达和蛋白质合成。用酪氨酸激酶抑制剂预处理可消除ET-1、离子霉素、毒胡萝卜素和IL-1介导的PGHS-2 mRNA和蛋白质诱导作用。通过抑制[Ca2+]i升高或钙调蛋白激酶激活，可抑制ET-1、离子霉素和毒胡萝卜素诱导的蛋白质酪氨酸磷酸化，但不能抑制IL-1诱导的蛋白质酪氨酸磷酸化。研究得出结论，[Ca2+]i升高和钙调蛋白激酶激活是ET-1通过激活MC中非受体连接的蛋白酪氨酸激酶诱导PGHS-2基因表达的上游介质。
