Expression of rabbit cytochromes P4504A which catalyze the omega-hydroxylation of arachidonic acid, fatty acids, and prostaglandins.
Expression of rabbit cytochromes P4504A which catalyze the omega-hydroxylation of arachidonic acid, fatty acids, and prostaglandins.
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兔细胞色素 P4504A 的表达，催化花生四烯酸、脂肪酸和前列腺素的 omega-羟基化。
DOI：
10.1006/abbi.1993.1560
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发表时间：
1993
影响因子：
3.9
通讯作者：
Masters,BS
中科院分区：
文献类型：
--
作者：
Roman,LJ;Palmer,CN;Clark,JE;Muerhoff,AS;Griffin,KJ;Johnson,EF;Masters,BS
花生四烯酸的ω-羟基化产物被认为是肾脏中有效的血管收缩剂或其前体。在这份报告中，我们已经测量了四种兔CYP 4A酶的能力，每种酶在COS-1细胞中表达，催化花生四烯酸的ω-羟基化。这些速率进行了比较，获得的其他底物，如月桂酸，棕榈酸，和前列腺素PGE 1和PGA 1。除P4504 A5外，所有测试的酶都表现出相对高的花生四烯酸ω-羟基化速率。P4504 A5对花生四烯酸或棕榈酸的活性与对月桂酸的活性相比非常小（<10%）。相比之下，P4504 A6和P4504 A7催化花生四烯酸的ω-羟基化反应的速率大约是月桂酸观察到的速率的50%。P4504 A4对月桂酸没有活性，但它也催化花生四烯酸的ω-羟基化，其速率约为PGE 1的20%。因此，每种酶在这组底物中表现出不同的底物特异性谱。使用灵敏的RNA酶保护测定来提供对来自对照、妊娠和氯贝酯处理的动物的肝脏和肾脏中编码P4504 A5、P4504 A6和P4504 A7的mRNA的相对丰度的更定量的估计。CYP 4A 5是最丰富的mRNA，但它在肾脏中没有被氯贝酸诱导，在肝脏中仅中度（2倍）被氯贝酸诱导。CYP 4A 7表现出类似的氯贝特诱导模式。相反，CYP 4A 6在肝脏中诱导12倍，在肾脏中诱导6倍。较高的诱导率在很大程度上反映了CYP 4A 6的基础表达水平低于CYP 4A 7和CYP 4A 5。在用氯贝特处理后，CYP 4A 6 mRNA的量与CYP 4A 5和CYP 4A 7的量相似。妊娠并不影响CYP 4A 5、CYP 4A 6或CYP 4A 7的表达，尽管妊娠可诱导CYP 4A 4在肝脏和肾脏中的表达达到可检测水平，但在非妊娠动物中通常不会发现。我们的研究结果表明，其mRNA被氯贝酸（P4504 A6）诱导最高的酶和在妊娠期间选择性升高的酶（P4504 A4）都表现出相对较高的花生四烯酸ω-羟基化速率。
The ω-hydroxylation product of arachidonic acid is thought to be a potent vasoconstrictor or a precursor thereof in kidney. In this report, we have measured the capacity of four rabbit CYP4A enzymes, each expressed in COS-1 cells, to catalyze the ω-hydroxylation of arachidonic acid. These rates were compared to those obtained for other substrates such as lauric acid, palmitic acid, and prostaglandins PGE1and PGA1. With the exception of P4504A5, all of the enzymes tested exhibited relatively high rates for the ω-hydroxylation of arachidonic acid. P4504A5 showed very little activity toward arachidonic or palmitic acids as compared to that toward lauric acid (<10%). In contrast, P4504A6 and P4504A7 catalyzed the ω-hydroxylation of arachidonic acid at rates that were roughly 50% of that observed for lauric acid. P4504A4 was not active toward lauric acid, but it also catalyzed the ω-hydroxylation of arachidonic acid at a rate that was roughly 20% of that exhibited for PGE1. Thus, each enzyme exhibits a distinct substrate specificity profile across this panel of substrates. A sensitive RNase protection assay was used to provide a more quantitative estimate of the relative abundance of mRNAs encoding P4504A5, P4504A6, and P4504A7 in liver and kidney from control, pregnant, and clofibrate-treated animals. CYP4A5 is the most abundant of the mRNAs, but it was not induced in kidney and only moderately (2-fold) in liver by clofibric acid. CYP4A7 exhibits a similar pattern of induction by clofibrate. In contrast, CYP4A6 is induced 12-fold in liver and 6-fold in kidney. The higher induction ratio largely reflects a lower basal level of expression for CYP4A6 than for CYP4A7 and CYP4A5. Following treatment with clofibrate, the amount of CYP4A6 mRNA is similar to those of CYP4A5 and CYP4A7. Pregnancy did not affect the expression of CYP4A5, CYP4A6, or CYP4A7, although it induced the expression of CYP4A4 to detectable levels in the liver and kidney, where it is not normally found in nonpregnant animals. Our results indicate that the enzyme whose mRNA is most highly induced by clofibric acid (P4504A6) and the enzyme selectively elevated during pregnancy (P4504A4) both exhibit relatively high rates for the ω-hydroxylation of arachidonic acid.