Bell D R, Elcombe C R
Biochemical Toxicology, ICI Central Toxicology Laboratory, Macclesfield, Cheshire, U.K.
Biochem J. 1991 Nov 15;280 ( Pt 1)(Pt 1):249-53. doi: 10.1042/bj2800249.
We have characterized the induction of acyl-CoA oxidase and cytochrome P450IVA1 RNAs in a primary hepatocyte culture system in vitro, using a sensitive and specific RNAse protection assay. Hepatocytes were cultured with a maximal inducing dose of the peroxisome proliferator clofibric acid (1 mM), or vehicle control, for 4 days, and the level of RNAs compared with the level in rats which had been treated with corn oil or clofibric acid (300 mg/kg) for 4 days. The level of acyl-CoA oxidase and P450IVA1 RNAs in 4-day-old control hepatocytes was less than 2% of that in control liver. However, the level of these RNAs in RNA from treated hepatocytes was 61% of that in liver RNA from treated rats. Hepatocytes were treated with the potent peroxisome proliferator methylclofenapate (100 microM), and the induction of RNAs determined at various times after exposure. P450IVA1 RNA was significantly induced 1 h after dosing, rising to 34-fold above control after 8 h, whereas acyl-CoA oxidase RNA was not significantly induced until 4 h, increasing to 5.2-fold above control after 8 h. A similar time course of induction was seen after treatment of hepatocytes with 100 microM-nafenopin, 100 microM-methylclofenapate, 1 mM-clofibric acid or 1 mM-mono(ethylhexyl) phthalate, suggesting that the differential time course of induction of P450IVA1 and acyl-CoA oxidase RNAs is not related to the esterification, structure or potency of the peroxisome proliferator, but is intrinsic to the process of peroxisome proliferation. Hepatocytes were treated with methylclofenapate in the presence and absence of cycloheximide. P450IVA1 RNA was significantly induced by methylclofenapate in the presence of cycloheximide, rising to 17-fold above control after 8 h. However, no induction of acyl-CoA oxidase RNA was detected in the presence of cycloheximide. Therefore we characterize the induction of acyl-CoA oxidase and P450IVA1 RNAs in primary hepatocyte culture in vitro as a faithful model of the induction response in rat liver, and suggest that induction of P450IVA1 RNA is a primary event in the process of peroxisome proliferation.
我们利用灵敏且特异的核糖核酸酶保护分析，在体外原代肝细胞培养系统中对酰基辅酶A氧化酶和细胞色素P450IVA1 RNA的诱导情况进行了表征。将肝细胞用最大诱导剂量的过氧化物酶体增殖剂氯贝酸（1 mM）或溶剂对照培养4天，并将RNA水平与用玉米油或氯贝酸（300 mg/kg）处理4天的大鼠的RNA水平进行比较。4日龄对照肝细胞中酰基辅酶A氧化酶和P450IVA1 RNA的水平不到对照肝脏中该水平的2%。然而，处理过的肝细胞RNA中这些RNA的水平是处理过的大鼠肝脏RNA中该水平的61%。用强效过氧化物酶体增殖剂甲基氯苯那酯（100 microM）处理肝细胞，并在暴露后的不同时间测定RNA的诱导情况。给药1小时后，P450IVA1 RNA显著诱导，8小时后升至对照水平以上34倍，而酰基辅酶A氧化酶RNA直到4小时才显著诱导，8小时后增加到对照水平以上5.2倍。在用100 microM-萘夫平、100 microM-甲基氯苯那酯、1 mM-氯贝酸或1 mM-邻苯二甲酸单（2-乙基己基）酯处理肝细胞后，观察到了类似的诱导时间进程，这表明P450IVA1和酰基辅酶A氧化酶RNA诱导的不同时间进程与过氧化物酶体增殖剂的酯化、结构或效力无关，而是过氧化物酶体增殖过程所固有的。在有和没有放线菌酮的情况下用甲基氯苯那酯处理肝细胞。在有放线菌酮的情况下，甲基氯苯那酯显著诱导P450IVA1 RNA，8小时后升至对照水平以上17倍。然而，在有放线菌酮的情况下未检测到酰基辅酶A氧化酶RNA的诱导。因此，我们将体外原代肝细胞培养中酰基辅酶A氧化酶和P450IVA1 RNA的诱导表征为大鼠肝脏诱导反应的可靠模型，并表明P450IVA1 RNA的诱导是过氧化物酶体增殖过程中的一个主要事件。
Zotero 插件