Sharma R K, Lake B G, Makowski R, Bradshaw T, Earnshaw D, Dale J W, Gibson G G
Department of Biochemistry, University of Surrey, Guildford, England.
Eur J Biochem. 1989 Sep 1;184(1):69-78. doi: 10.1111/j.1432-1033.1989.tb14991.x.
The induction of renal fatty-acid-oxidising enzymes has been investigated following short-term exposure to a group of structurally diverse peroxisome proliferators and compared to the more extensively documented hepatic responses in the rat. There was a marked compound dependence on induction of both cytochrome P-450-IVA1-dependent omega-hydroxylation of lauric acid and enzymes of the peroxisomal fatty acid beta-oxidation pathway (measured as cyanide-insensitive palmitoyl-CoA oxidation and enoyl-CoA hydratase). Cytochrome P-450 IVA1 (or a very closely related isoenzyme in the same gene family) was a major constitutive haemoprotein in rat kidney microsomes and actively supported the omega-hydroxylation of lauric acid. This activity was induced 2-3-fold by peroxisome proliferators such as clofibrate, di-(2-ethylhexyl)phthalate, bezafibrate and nafenopin. By using a cDNA probe to the cytochrome P-450 IVA1 gene in Northern blot analysis, we have shown that increased renal and hepatic omega-hydroxylation of lauric acid, after treatment with peroxisome proliferators is a consequences of a substantial increase in the mRNA coding for this haemoprotein. In addition, programming of an in vitro rabbit reticulocyte translation system with both renal and hepatic RNA resulted in the synthesis of similar (if not identical) cytochrome-P-450-IVA1-related polypeptides. Furthermore, we have provided Western blot evidence that both rat liver and kidney microsomes contain two closely related cytochrome P-450 IVA1 polypeptides, the major one characterised by a monomeric molecular mass of 51.5 kDa (identical to authentic, purified hepatic cytochrome P-450 IVA1) and a minor one of 52 kDa. The kidney-supported fatty acid omega-hydroxylase activity was refractory to inhibition by a polyclonal antibody to liver cytochrome P-450 IVA1, which may be related to the existence of two closely related (but immunochemically distinct) fatty acid hydroxylases in this tissue. Our studies have also demonstrated that certain of the compounds tested (including clofibrate, bezafibrate and nafenopin) induced renal fatty acid beta-oxidation, mirroring the increased omega-hydroxylase activity in the endoplasmic reticulum. Our studies have also indicated that the kidney was more refractory to induction of the endoplasmic reticulum and peroxisomal fatty-acid-oxidising enzymes than the liver. Taken collectively, our data is strongly suggestive of a possible linkage of the renal fatty acid oxidative enzymes in these two organelles, a situation that also occurs in the liver. In addition, our studies have provided a possible conceptual framework that may rationalise the decreased susceptibility of the k
在短期暴露于一组结构各异的过氧化物酶体增殖剂后，对大鼠肾脂肪酸氧化酶的诱导情况进行了研究，并与已被更广泛记录的肝脏反应进行了比较。月桂酸的细胞色素P - 450 - IVA1依赖性ω - 羟化以及过氧化物酶体脂肪酸β - 氧化途径的酶（以对氰化物不敏感的棕榈酰辅酶A氧化和烯酰辅酶A水合酶来衡量）的诱导存在明显的化合物依赖性。细胞色素P - 450 IVA1（或同一基因家族中非常密切相关的同工酶）是大鼠肾微粒体中的一种主要组成血红蛋白，并积极支持月桂酸的ω - 羟化。这种活性被氯贝丁酯、邻苯二甲酸二（2 - 乙基己基）酯、苯扎贝特和萘酚平之类的过氧化物酶体增殖剂诱导2 - 3倍。通过在Northern印迹分析中使用细胞色素P - 450 IVA1基因的cDNA探针，我们已经表明，用过氧化物酶体增殖剂处理后，肾和肝中月桂酸的ω - 羟化增加是该血红蛋白编码mRNA大量增加的结果。此外，用肾和肝RNA对体外兔网织红细胞翻译系统进行编程导致合成了相似（如果不是相同）的细胞色素 - P - 450 - IVA1相关多肽。此外，我们提供了蛋白质印迹证据，表明大鼠肝和肾微粒体都含有两种密切相关的细胞色素P - 450 IVA1多肽，主要的一种以单体分子量51.5 kDa为特征（与纯化的肝脏细胞色素P - 450 IVA1相同），次要的一种为52 kDa。肾支持的脂肪酸ω - 羟化酶活性对针对肝脏细胞色素P - 450 IVA1的多克隆抗体的抑制具有抗性，这可能与该组织中存在两种密切相关（但免疫化学上不同）的脂肪酸羟化酶有关。我们的研究还表明，所测试的某些化合物（包括氯贝丁酯、苯扎贝特和萘酚平）诱导了肾脂肪酸β - 氧化，反映了内质网中ω - 羟化酶活性的增加。我们的研究还表明，与肝脏相比，肾脏对内质网和过氧化物酶体脂肪酸氧化酶的诱导更具抗性。总体而言，我们的数据强烈暗示这两个细胞器中的肾脂肪酸氧化酶可能存在联系，这种情况在肝脏中也会发生。此外，我们的研究提供了一个可能的概念框架，这可能使肾脏对……敏感性降低的情况合理化
