INTERLEUKIN-1-ALPHA CAUSES RAPID ACTIVATION OF CYTOSOLIC PHOSPHOLIPASE A(2) BY PHOSPHORYLATION IN RAT MESANGIAL CELLS
INTERLEUKIN-1-ALPHA CAUSES RAPID ACTIVATION OF CYTOSOLIC PHOSPHOLIPASE A(2) BY PHOSPHORYLATION IN RAT MESANGIAL CELLS
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DOI：
10.1172/jci117076
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发表时间：
1994-03-01
影响因子：
15.9
通讯作者：
SEDOR, JR
中科院分区：
文献类型：
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作者：
GRONICH, J;KONIECZKOWSKI, M;SEDOR, JR
我们之前已经证明，白细胞介素1 （IL-1）通过重新合成一种14kd的II组磷脂酶a (2) （PLA(2)）刺激肾小球系膜细胞（MC）中类二十烷酸的产生。il -1刺激的前列腺素E(2)合成先于该酶的表达，这表明另一种PLA(2)异构体必须更快地被激活。在钙离子载体存在但不存在的情况下，早在添加IL-1后5分钟，[H-3]花生四烯酸酯的释放就会显著增加，并且IL-1同时刺激Ca2+依赖性磷脂酶活性，其特征为胞质形式的PLA(2) （cPLA(2)）。IL-1不改变血清刺激MC中cPLA(2) mRNA的表达或质量，表明cPLA的活性通过翻译后修饰而增加。IL-1处理30 min，双P-32掺入免疫可沉淀的cPLA(2)蛋白中，与酶活性增加一致。对IL-1处理（30分钟）的细胞提取物进行免疫印迹分析显示，cPLA的流动性降低(2)，用酸性磷酸酶处理MC裂解物显著降低细胞因子激活的cPLA(2)活性，进一步表明IL-1刺激酶的磷酸化。IL-1处理（24 h）使血清缺失的MC的cPLA(2) mRNA、蛋白和活性增加一倍。总之，IL-1通过翻译后修饰和从头合成以双相、时间依赖的方式增加cPLA(2)活性。我们认为，cPLA(2)激活是il -1刺激的促炎、脂质介质合成的关键步骤，也是该细胞因子在靶细胞中诱导的表型反应中不可或缺的事件。
We have shown previously that interleukin 1 (IL-1) stimulates eicosanoid production in glomerular mesangial cells (MC) by de novo synthesis of a 14-kD, group II phospholipase A(2) (PLA(2)). IL-1-stimulated prostaglandin E(2) synthesis precedes espression of this enzyme, suggesting that another PLA(2) isoform must be more rapidly activated. In the presence but not absence of calcium ionophore, [H-3]arachidonate release is increased significantly as early as 5 min after addition of IL-1, and IL-1 concurrently stimulates a Ca2+-dependent phospholipase activity, which was characterized as the cytosolic form of PLA(2) (cPLA(2)). IL-1 does not alter either cPLA(2) mRNA expression or mass in serum-stimulated MC, suggesting that cPLA, activity is increased by a posttranslational modification. IL-1 treatment for 30 min doubles P-32 incorporation into immunoprecipitable cPLA(2), protein, concordant with the increase in enzyme activity. Immunoblot analysis of extracts derived from IL-1-treated (30 min) cells demonstrates a decreased mobility of cPLA(2), and treatment of MC lysates with acid phosphatase significantly reduces cytokine-activated cPLA(2) activity, further indicating that IL-1 stimulates phosphorylation of the enzyme. IL-1 treatment (24 h) of serum-deprived MC doubled cPLA(2) mRNA, protein, and activity. In summary, IL-1 increases cPLA(2) activity in a biphasic, time-dependent manner both by posttranslational modification and de novo synthesis. We consider cPLA(2) activation a key step in IL-1-stimulated synthesis of pro-inflammatory, lipid mediators, and an integral event in the phenotypic responses induced in target cells by this cytokine.