| Abstract: | 17-氫氧酵素(17.alpha.-hydroxylase, P-450c17)是類固醇賀爾蒙生合成途徑主要酵素之一。其主要功能為催化Pregnenolone和Progesterone第17個碳之氧化作用,及切斷碳17和20之間之共價鍵。於大多數之動物(如人或牛),17-氫氧酵素存在於腎上腺及性器官中,分別負責Cortisol及性賀爾蒙之合成。然而大白鼠之17-氫氧酵素只存在於性器官中,於腎上腺卻無法測得此酵素之活性。此現象可能涉及細胞分化時基因經過某些修飾,導致於不同細胞中有不同之表現。本計畫針對17-氫氧酵素之基因進行研究,探討可能導致此基因於大白鼠之腎上腺與睪丸中差異表現之因素。 首先,於預備性實驗中利用RTPCR技術將17-氫氧酵素之cDNA單離出來,並成功地轉入pGEM3zf(-)。之後,應用此cDNA為探針從事Norther hybridization實驗,結果確認腎上腺無法表現17-氫氧酵素。為了排除此結果乃源於17-氫氧酵素RNA的快速分解,Nuclear run-on transcription實驗被用來檢驗此酵素基因於腎上腺與睪丸中之轉錄控制。其結果仍在評估當中。
17.alpha.-hydroxylase (P-450c17), one of the steroidogenic enzymes, is expressed in both adrenal and gonad for the synthesis of cortisol and androgens in most species (such as human and bovine). In rats and some other species, however, there is no 17.alpha.-hydroxylating activity in the adrenal. It is an intriguing phenomenon that the gene of 17.alpha.-hydroxylase is expressed differentially in the rat adrenal and gonad, since both organ are responsible for steroidogenesis. This project studied the possible causes that may lead to the differential expression of 17.alpha.-hydroxylase gene in the rat adrenal and testis. In the preliminary experiments, the cDNA of 17.alpha.-hydroxylase was isolated from the total RNA of rat testis by RTPCR technique. The 1.7Kb cDNA was cloned into pGEM3zf(-) vector and used as a probe for Northern Hybridization study. The results confirmed that the rat adrenal did not express 17.alpha.-hydroxylase. To rule out the possibility that the absence of 17-.alpha.hydroxylase RNA was due to rapid degradation, nuclear run-on transcription assay was performed. The result is still evaluated. |
