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Abstract：
The synthesis of 11-ketotestosterone (11KT) and estradiol-17β (E2), which play important roles in the regulation of gametogenesis in teleost fishes, is catalyzed by several steroidogenic enzymes. In particular, 17β-hydroxysteroid dehydrogenases (Hsd17bs) with 17-ketosteroid reducing activity (17KSR activity) are essential enzymes in the formation of these sex steroid hormones in the gonads and other tissues. Retinol dehydrogenase 11 (RDH11) has been suggested to be a novel tentative HSD17B (HSD17B15) in humans for a decade, however no definitive proof has been provided yet. In this study, three cDNAs related to human RDH11 were isolated from Japanese eel testis and characterized. Sequence similarity and phylogenetic analyses revealed their close relationship to human rdh11 and rdh12 gene products and they were designated as rdh11/12-like 1, rdh11/12-like 2, and rdh11/12-like 3. Three recombinant Rdh11/12-like proteins expressed in HEK293T cells catalyzed the transformation of estrone into E2 and androstenedione into testosterone. Only Rdh11/12-like 1 catalyzed the conversion of 11-ketoandrostenedione into 11KT. Tissue-distribution analysis by quantitative real-time polymerase chain reaction revealed, in immature male Japanese eel, that rdh11/12-like 1 and rdh11/12-like 2 are predominantly expressed in testis and brain, while rdh11/12-like 3 is expressed ubiquitously. Moreover, we analyzed the effects of gonadotropins and 11KT on the expression of the three rdh11/12-like mRNAs in the immature testis. In vitro incubation of immature testes with various doses of recombinant Japanese eel follicle stimulating hormone, luteinizing hormone, and 11KT indicated that the expression of rdh11/12-like 1 mRNA, rdh11/12-like 2, and rdh11/12-like 3 did not change. These findings suggest that the three Rdh11/12-like proteins metabolize sex steroids. Rdh11/12-like 1 may be one of the enzymes with 17KSR activity involved in the production of 11KT in the testis.
摘要：
11-酮雌酮酮(11KT)和雌二醇-17β(E2)的合成,在硬骨鱼配子发生的调控中起着重要作用，由几种类固醇生成酶催化。特别是,具有17-酮类固醇还原活性（17KSR活性）的17β-羟基类固醇脱氢酶（Hsd17bs）是性腺和其他组织中这些性类固醇激素形成的必需酶。十年来，视黄醇脱氢酶11（RDH11）已被认为是人类新的暂定HSD17B（HSD17B15）。然而，尚未提供确切的证据。在这项研究中,从日本鳗鱼睾丸中分离出与人RDH11相关的三个cDNA并进行了表征。序列相似性和系统发育分析显示它们与人类rdh11和rdh12基因产物密切相关，它们被命名为rdh11/12样1、rdh11/12样2和rdh11/12样3。在HEK293T细胞中表达的三种重组Rdh11/12样蛋白催化雌酮转化为E2和雄烯二酮转化为睾酮。只有Rdh11/12样1催化11-酮雄烯二酮转化为11KT。通过定量实时聚合酶链反应进行的组织分布分析显示，不成熟的雄性日本鳗鱼，rdh11/12样1和rdh11/12样2主要在睾丸和大脑中表达，而rdh11/12样3广泛表达。此外，我们分析了促性腺激素和11KT对未成熟睾丸中三种rdh11/12样mRNA表达的影响。用各种剂量的重组日本鳗鱼卵泡刺激素体外培养未成熟睾丸，黄体生成素,和11KT表明rdh11/12样1mRNA的表达，rdh11/12-like2和rdh11/12-like3没有改变。这些发现表明，这三种Rdh11/12样蛋白可以代谢性类固醇。Rdh11/12样1可能是具有17KSR活性的酶之一，参与睾丸中11KT的产生。
