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Molecular biological studies on arachidonate oxygenase isozymes

花生四烯酸加氧酶同工酶的分子生物学研究

基本信息

批准号：
08457039
负责人：
YAMAMOTO Shozo
金额：
$ 4.8万
依托单位：
The University of Tokushima
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08457039/
关键词：
Archidonic acid Cyclooxygenase Lipoxygenase Isozyme Prostaglandin Enzyme induction Transcriptional regulation Biomedulator

项目摘要

There are two isozymes of 12-lipoxygenase distinguishable in terms of substrate specificity and primary structure. Two cycloowoygenase isozymes are known : the previously known enzyme (COX-1) and the recently found isozyme (COX-2). Their physiological and pathological functions are subjects of active invesigations. This research project is for the studies on the induction of the isozymes in pathophysiological conditions and the transcriptional regulation of the isozyme genes, and the following experimental results were obtained.1) Transcriptional regulation of COX-1 gene : Addition of a phorbol ester induced COX-1 in human megakaryoblastic cells CMK along with their differentiation to megakaryocytes. We found the presence of prostaglandin D synthase in megakaryoblasts which is absent in platelets.2) Transcriptional regulation of COX-2 gene : Induction of COX-2 by TNFalpha was demonstrated with murine osteoblastic cells MC3T3-E1, and involvement of NFkappaB and NF-IL6 were shown. COX-2 induction was also observed in rat pluerisy model.3) Suicide inactivation of 12-lipoxygenase isozymes : Leukocyte 12-lipoxygenase shows a marked inactivation during its catalysis while platelet 12-lipoxygenase reaction proceeded almost linearly. The suicide inactivation of the leukocyte enzyme was attributed to its production of 15-hydroperoxy acid in addition to 12-hydroperoxy acid and to the coversion of the former minor product to a 14,15-epoxide.4) Transcriptional regulation of 12-lipoxygenase gene : In collaboration with Taiwanese group 12-lipoxygenase induction of EGF in human epidermoid carcinoma cells A431 was demonstrated, and involvement of SP-1 was suggested in the transcription of the enzyme gene. Furthermore, diurnal change of 12-lipoxygenase mRNA was observed in rat pineal gland.

12-脂氧合酶有两种同工酶，它们在底物特异性和一级结构上是不同的。已知有两种环氧合酶同工酶：先前已知的酶（考克斯-1）和最近发现的同工酶（考克斯-2）。它们的生理和病理功能是人们积极研究的课题。本研究旨在研究病理生理条件下同功酶的诱导及其基因转录调控，获得了以下实验结果：1）考克斯-1基因的转录调控：加入佛波醇酯诱导人巨核母细胞CMK沿着向巨核细胞分化的考克斯-1。2）考克斯-2基因的转录调控：在小鼠成骨细胞MC 3 T3-E1中证实了TNF α对考克斯-2的诱导作用，并显示了NF κ B和NF-IL 6的参与。考克斯-2在大鼠肺栓塞模型中也有诱导作用。3）12-脂氧合酶同工酶的自杀性失活：白细胞12-脂氧合酶在催化过程中表现出明显的失活，而血小板12-脂氧合酶反应几乎呈线性进行。白细胞酶的自杀性失活归因于其除了12-氢过氧酸之外还产生15-氢过氧酸，以及将前一个次要产物转化为14，15-环氧化物。4）12-脂氧合酶基因的转录调节：与台湾组合作，在人表皮样癌细胞A431中证实了12-脂氧合酶对EGF的诱导，SP-1参与了该酶基因的转录。此外，还观察到大鼠松果体12-脂氧合酶mRNA的昼夜变化。