Kim S G, Novak R F
Institute of Chemical Toxicology, Wayne State University, Detroit, MI 48201.
Biochem Biophys Res Commun. 1990 Feb 14;166(3):1072-9. doi: 10.1016/0006-291x(90)90976-t.
The dose- and time-dependent induction of P45OIIE1 in rat liver by pyridine has been characterized. A single injection of pyridine (100 mg/kg, i.p.) increased P450IIE1 levels 2-, 3- and 4-fold at 6, 10 and 24 hr, respectively, relative to controls as evidenced by metabolic activity and Western blot analysis. Induction of IIE1 was dose-dependent over the range 10 to 200 mg/kg. Cycloheximide administration completely prevented the induction of P450IIE1 by pyridine, whereas actinomycin D administration had no appreciable effect. Pyridine induction of IIE1 did not occur by transcriptional activation. Hybridization analysis failed to reveal an increase in IIE1 message in either total RNA or poly(A+) mRNA following pyridine treatment, although a slight decrease in poly(A+) mRNA was noted. The rate of P450IIE1 synthesis was assessed by labelling of proteins with [14C]leucine in vivo, followed by autoradiographic analysis. Increased intensity of a protein band comigrating with purified IIE1 was observed in microsomes isolated from rats at 5 hr following either pyridine or acetone treatment, as compared to controls. An increase in intensity was also noted for protein bands migrating in the region of 62 and 50 kDa. These results suggest that induction of P450IIE1 at early times following acute pyridine exposure involves protein synthesis possibly through increased translational efficiency.
已对吡啶在大鼠肝脏中诱导P450IIE1的剂量和时间依赖性进行了表征。单次注射吡啶（100mg/kg，腹腔注射）后，相对于对照组，在6、10和24小时时，P450IIE1水平分别升高了2倍、3倍和4倍，代谢活性和蛋白质印迹分析证明了这一点。在10至200mg/kg范围内，IIE1的诱导呈剂量依赖性。给予环己酰亚胺可完全阻止吡啶对P450IIE1的诱导，而给予放线菌素D则没有明显效果。吡啶对IIE1的诱导不是通过转录激活发生的。杂交分析未能揭示吡啶处理后总RNA或聚腺苷酸（A+）mRNA中IIE1信息的增加，尽管注意到聚腺苷酸（A+）mRNA略有减少。通过在体内用[14C]亮氨酸标记蛋白质，然后进行放射自显影分析来评估P450IIE1的合成速率。与对照组相比，在吡啶或丙酮处理后5小时从大鼠分离的微粒体中，观察到与纯化的IIE1共迁移的蛋白条带强度增加。在62和50kDa区域迁移的蛋白条带强度也有所增加。这些结果表明，急性吡啶暴露后早期P450IIE1的诱导可能涉及蛋白质合成，可能是通过提高翻译效率实现的。
