P450c17s基因mRNA在雄性半滑舌鳎繁殖周期中的表达

The characteristic analysis of P450c17s mRNA expression during the reproductive cycle in male Cynoglossus semilaevis Günther

利用已克隆得到的半滑舌鳎P450c17-I和P450c17-Ⅱ基因cDNA全长序列,通过半定量RT-PCR技术,结合雄鱼性腺发育期、各发育期血清中睾酮(T)含量,研究了这两个基因在雄性半滑舌鳎各组织内的空间表达及在雄鱼繁殖周期中的季节性表达。结果表明,半滑舌鳎P450c17-I组织分布具有广泛性,在精巢、胃、肠、心、脾和脑内都有表达,而P450c17-II组织分布具有特异性,仅在精巢和头肾内有表达。在精巢不同发育期内,P450c17-I表达与性腺发育呈正相关,而P450c17-II表达模式则相反。推测这可能是由于在整个繁殖期,P450c17-I基因在转录水平或转录后调控半滑舌鳎性类固醇激素的生成,而P450c17-II主要可能与孕激素诱导排精及精原细胞DNA复制有关。

Cytochrome P450c17 is one of the most critical enzymes in steroidogenic pathway, which is essential in the production of sex steroid hormone（androgens and estrogens）. Up to date, there are two P450c17s （P450c17-I and P450c17-II ） encoded by two different genes. P450c17-I possesses two enzyme activities, namely 17a-hydroxylase and 17, 20-1yase, while P450c 17-11 only has 17a-hydroxylase. Under the condition of＇ P450c17-I and P450c17-]I complete cDNAs, the spatial and temporal expressions of the two genes are studied by the semi-RT-PCR technology, combined with gonad development and serum tes- tosterone（T） level. The results of gene spatial expression analysis showed that tongue sole P450c17-I was distributed widely, which was expressed in testis, stomach, intestine, heart, spleen and brain, while tongue sole P450c 17-II distribution was tissue-specific, which was only expressed in testis and head kidney. Dur- ing various developmental stages of testis, P450c17-I expression pattern revealed developmental stage-dependency, while the expression pattern of P450c17-II was on the contrary. It is predicted that, during the whole reproductive period, P450c17-I regulates the sex steroid hormone on the transcriptional level or after transcription in male tongue sole, while P450c 17-II may be related to progestin in inducing spermiation and DNA replication in spermatogonia.