Nakamura Ikumi, Evans Jennifer C, Kusakabe Makoto, Nagahama Yoshitaka, Young Graham
School of Aquatic and Fishery Sciences, University of Washington, Seattle WA 98105, USA.
Gen Comp Endocrinol. 2005 Dec;144(3):224-31. doi: 10.1016/j.ygcen.2005.06.004. Epub 2005 Aug 15.
In salmonid fishes, estradiol-17beta (E2) and 17alpha,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) are the major steroid hormones controlling oocyte growth (vitellogenesis) and final maturation (resumption of meiosis). The aim of this study was to determine changes in mRNAs encoding ovarian steroidogenic enzymes and steroidogenic acute regulatory protein (StAR) during ovarian development in female rainbow trout. We analyzed the levels of mRNAs encoding the enzymes P450 side-chain cleavage enzyme (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17alpha-hydroxylase/C17-C20 lyase (P450c17), aromatase (P450arom), and carbonyl reductase-like 20beta-hydroxysteroid dehydrogenase (20beta-HSD), and StAR in developing ovarian follicles of rainbow trout by Northern blot, in relation to the pattern of serum E2 and 17,20beta-P levels. Serum E2 levels were elevated during vitellogenesis and decreased prior to an ovulatory increase in 17,20beta-P. Transcripts for P450scc and P450c17 increased in late vitellogenic follicles, then decreased in post-ovulatory follicles. In contrast, P450arom transcripts were abundant during vitellogenesis and then declined as vitellogenesis was completed and were barely detectable in post-ovulatory follicles. 3beta-HSD mRNA levels increased in late vitellogenic follicles and were maintained at high levels in post-ovulatory follicles. 20beta-HSD and StAR mRNA levels were very low during vitellogenesis, and then strongly increased during late vitellogenesis to a peak in post-ovulatory follicles. These results indicate that the expression of genes encoding steroidogenic enzymes and StAR change dynamically, dependent on the developmental stages of rainbow trout follicles. The acquisition of the ability of later stage follicles to rapidly produce large quantities of 17,20beta-P appears to be supported by a preparatory increase in mRNAs encoding StAR and other steroidogenic enzymes.
在鲑科鱼类中，17β-雌二醇（E2）和17α,20β-二羟基-4-孕烯-3-酮（17,20β-P）是控制卵母细胞生长（卵黄发生）和最终成熟（减数分裂恢复）的主要类固醇激素。本研究的目的是确定雌性虹鳟卵巢发育过程中编码卵巢类固醇生成酶和类固醇生成急性调节蛋白（StAR）的mRNA的变化。我们通过Northern印迹分析了虹鳟发育中卵巢卵泡中编码细胞色素P450侧链裂解酶（P450scc）、3β-羟基类固醇脱氢酶（3β-HSD）、17α-羟化酶/C17-C20裂解酶（P450c17）、芳香化酶（P450arom）、羰基还原酶样20β-羟基类固醇脱氢酶（20β-HSD）和StAR的mRNA水平，并与血清E2和17,20β-P水平的变化模式相关联。在卵黄发生期间血清E2水平升高，在排卵前17,20β-P升高之前降低。P450scc和P450c17的转录本在卵黄发生后期的卵泡中增加，然后在排卵后卵泡中减少。相反，P450arom转录本在卵黄发生期间丰富，然后随着卵黄发生完成而下降，在排卵后卵泡中几乎检测不到。3β-HSD mRNA水平在卵黄发生后期的卵泡中增加，并在排卵后卵泡中维持在高水平。20β-HSD和StAR mRNA水平在卵黄发生期间非常低，然后在卵黄发生后期强烈增加，在排卵后卵泡中达到峰值。这些结果表明，编码类固醇生成酶和StAR的基因表达动态变化，取决于虹鳟卵泡的发育阶段。编码StAR和其他类固醇生成酶的mRNA的预先增加似乎支持了后期卵泡快速产生大量17,20β-P的能力的获得。
