Malaska T, Payne A H
J Biol Chem. 1984 Oct 10;259(19):11654-7.
Treatment of mouse Leydig cell cultures with luteinizing hormone (LH) or with 8-bromo-cAMP (8-Br-cAMP) for 5 days elicited a dose- and time-dependent increase in the microsomal cytochrome P-450 enzyme activities. 17 alpha-Hydroxylase and C17-20 lyase as well as a parallel increase in testosterone production. Reduction of the oxygen tension from 19 to 1% resulted in a greater increase in enzyme activity. Induction of microsomal cytochrome P-450 activities was 35 to 50% greater with 8-Br-cAMP than with LH and the increase in C17-20 lyase activity was 4-fold greater than that of 17 alpha-hydroxylase. Maximal induction of P-450 enzyme activities was observed between 3 and 5 days of continual treatment with 8-Br-cAMP or LH. Removal of 8-Br-cAMP from the culture medium inhibited any further increase in C17-20 lyase activity and testosterone production. The role of protein synthesis in the induction process was investigated by incubating Leydig cell cultures with and without cycloheximide between 24 and 48 h of treatment with 8-Br-cAMP. Cycloheximide completely inhibited the induction of C17-20 lyase activity and the increase in testosterone production. After removal of the inhibitor, cultures responded in a manner that paralleled induction in cultures that had not been treated with cycloheximide. In both cases, a 24-h lag period occurred prior to an increase in cytochrome P-450 activity. These data suggest that the increase in microsomal cytochrome P-450 activities represents an increase in enzyme synthesis and, furthermore, that reduction of oxygen tension decreases degradation of newly synthesized Leydig cell microsomal cytochrome P-450 activities as recently reported (Quinn, P.G., and Payne, A.H. (1984) J. Biol. Chem. 259, 4130-4135).
用促黄体生成素（LH）或8-溴环磷酸腺苷（8-Br-cAMP）处理小鼠睾丸间质细胞培养物5天，可引起微粒体细胞色素P-450酶活性呈剂量和时间依赖性增加。17α-羟化酶和C17-20裂解酶以及睾酮生成也相应增加。将氧张力从19%降至1%会导致酶活性有更大幅度的增加。8-Br-cAMP诱导微粒体细胞色素P-450活性比LH诱导的活性高35%至50%，且C17-20裂解酶活性的增加比17α-羟化酶活性的增加高4倍。在用8-Br-cAMP或LH持续处理3至5天期间观察到P-450酶活性的最大诱导。从培养基中去除8-Br-cAMP可抑制C17-20裂解酶活性和睾酮生成的进一步增加。通过在8-Br-cAMP处理24至48小时期间将睾丸间质细胞培养物与放线菌酮一起或不与放线菌酮一起孵育，研究了蛋白质合成在诱导过程中的作用。放线菌酮完全抑制了C17-20裂解酶活性的诱导和睾酮生成的增加。去除抑制剂后，培养物的反应方式与未用放线菌酮处理的培养物中的诱导情况相似。在两种情况下，细胞色素P-450活性增加之前均出现24小时的延迟期。这些数据表明，微粒体细胞色素P-450活性的增加代表酶合成的增加，此外，如最近报道的（奎因，P.G.，和佩恩，A.H.（1984年）《生物化学杂志》259，4130 - 4135），氧张力的降低会减少新合成的睾丸间质细胞微粒体细胞色素P-450活性的降解。
