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Arachidonate-preferential cytosolic phospholipases A_2 as novel signal transducers

花生四烯酸优先胞质磷脂酶 A_2 作为新型信号转导器

基本信息

批准号：
06454174
负责人：
KUDO Ichiro
金额：
$ 4.54万
依托单位：
Showa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06454174/
关键词：
phospholipase A_2 arachidonic acid inflammation MAP kinase phosphorylation ホスホリパーゼA_2

项目摘要

We have examined the expression and function of 85-kDa cytosolic phospholipase A_2 (cPLA_2) in mammalian cells.1. Whereas cPLA_2 is ubiqitously and constitutively expressed in most mammalian cells, the regulation of its expression after cell activation was found to differ among cell types : (1) in fibroblasts, cPLA_2 expression was almost constant even after cell activation by proinflammatory cytokines ; (2) in osteoblasts and mast cells, cPLA_2 protein expression increased markedly after cytokine stimulation, without accompanied by concomitant increase in its mRNA level, revealing significant post-translational regulation of cPLA_2 expression ; and (3) in macrophages, both cPLA_2 mRNA and protein increased after lipopolysaccharide stimulation. Of note, we found for the first time that increase in cPLA_2 expression underwent positive-feedback augmentation by PGA_2, which is an endoproduct of the prostanoid biosynthetic pathway, in mouse osteoblastic cells.2. The functional coupling of … More cPLA_2 with downstream cyclooxygenase (COX) enzymes in the different phases of the prostanoid biosynthetic pathway was investigated. (1) Fibroblasts, mast cells and macrophages produced PGE_2, PGD_2 and TXA_2, respectively, in the immediate phase of cell activation through functional coupling of cPLA_2 with constitutive COX-1. In contrast, cytokine-primed macrophages or osteoblasts, in which COX-2 had been already induced, produced PGE_2 in preference to other prostanoids in the immediate response where cPLA_2 and inducible COX-2 were functionally linked. (2) In the delayd phase of cell activation, most cells produced PGE_2 as a consequence of the functional coupling of cPLA_2 and COX-2. In macrophages, mast cells and fibroblasts, secretory type II PLA_2, often inducible, was also required for the optimal delayd prostanoid generation, revealing an unexplored crosstalk between the two distinct PLA_2 enzymes. Nevertheless, these studies imply that cPLA_2 is prerequisite for both immediate and delayd prostanoid biosynthesis, irespective of the differential regulation of its expression in various cells.3. Finally, in search for the protein that specifically interacts with cPLA_2, we identified a 60-kDa intracellular protein in several cell types. We aim to clarify the structure and function of this 60-kDs cPLA_2-interacting protein, which is assumed to act as a regulator of cPLA_2 function in cells. Less

我们研究了85-kDa胞浆型磷脂酶A_2（cPLA_2）在哺乳动物细胞中的表达和功能。cPLA_2在大多数哺乳动物细胞中广泛表达，但在细胞激活后其表达的调节因细胞类型而异：（1）在成纤维细胞中，cPLA_2的表达几乎不变，即使细胞被促炎细胞因子激活后也是如此;（2）在成骨细胞和肥大细胞中，cPLA_2蛋白表达在细胞因子刺激后显著增加，（3）巨噬细胞经脂多糖刺激后，cPLA_2mRNA和蛋白表达均增加。值得注意的是，我们首次发现小鼠成骨细胞中前列腺素生物合成途径的内产物PGA_2对cPLA_2表达的增加有正反馈作用。的功能耦合 ...更多信息研究了前列腺素生物合成途径不同阶段cPLA_2与下游环氧化酶（考克斯）的关系。(1)成纤维细胞、肥大细胞和巨噬细胞在细胞活化的即刻通过cPLA_2与组成型考克斯-1的功能偶联分别产生PGE_2、PGD_2和TXA_2。与此相反，已诱导考克斯-2的、经精氨酸预处理的巨噬细胞或成骨细胞，在cPLA_2和诱导型考克斯-2功能性连接的即时反应中，产生PGE_2的优先性高于其他前列腺素类。(2)在细胞活化的延迟期，大多数细胞产生PGE_2，这是cPLA_2和考克斯-2功能偶联的结果。在巨噬细胞、肥大细胞和成纤维细胞中，分泌型II型PLA_2，通常是可诱导的，也是最佳延迟前列腺素类生成所必需的，揭示了两种不同PLA_2酶之间的未探索的串扰。尽管如此，这些研究表明，cPLA_2是立即和延迟前列腺素类生物合成的先决条件，而无论其在不同细胞中表达的差异调节如何。3.最后，在寻找与cPLA_2特异性相互作用的蛋白质时，我们在几种细胞类型中鉴定了60-kDa的细胞内蛋白。我们的目的是阐明这个60 kDs的cPLA_2相互作用蛋白的结构和功能，它被认为是作为一个调节cPLA_2功能的细胞。少