Mizuta Takanobu, Kubokawa Kaoru
Center for Advanced Marine Research, Ocean Research Institute, University of Tokyo, Nakano, Tokyo 164-8639, Japan.
Endocrinology. 2007 Aug;148(8):3554-65. doi: 10.1210/en.2007-0109. Epub 2007 Apr 19.
The presence of sex steroids and their receptors has been demonstrated in all vertebrate groups from Agnatha to Mammalia but not in invertebrates. In genomic analyses of urochordates, cytochrome P450 (CYP) genes important for biosynthesis of sex steroids are absent. In the present study, we confirmed the presence of estrogen, androgen, and progesterone by using radioimmunoassay in gonads of amphioxus, Branchiostoma belcheri, which is considered to be evolutionarily closer to vertebrates than other invertebrates. Furthermore, CYP genes encoding CYP11A, CYP17, and CYP19 and transcripts for 17beta-hydroxysteroid dehydrogenase were cloned from amphioxus ovaries. Among invertebrates, the presence of hydroxysteroid dehydrogenase enzymes and metabolized steroids was shown in paracytic Taenia and corals. However, CYPs metabolizing sex steroids have not been demonstrated in invertebrates, nor has an attempt been made to consider the entire pathway from cholesterol to estrogen. This study is the first evidence to suggest the presence of CYP enzymes in sex steroid production in invertebrates.
从无颌纲到哺乳纲的所有脊椎动物类群中都已证实存在性类固醇及其受体，但在无脊椎动物中则未发现。在尾索动物的基因组分析中，对性类固醇生物合成至关重要的细胞色素P450（CYP）基因并不存在。在本研究中，我们通过放射免疫测定法证实了文昌鱼（Branchiostoma belcheri）性腺中存在雌激素、雄激素和孕酮，文昌鱼被认为在进化上比其他无脊椎动物更接近脊椎动物。此外，从文昌鱼卵巢中克隆出了编码CYP11A、CYP17和CYP19的CYP基因以及17β-羟基类固醇脱氢酶的转录本。在无脊椎动物中，在副肌绦虫和珊瑚中发现了羟基类固醇脱氢酶和代谢类固醇。然而，在无脊椎动物中尚未证实存在代谢性类固醇的CYP，也没有人尝试考虑从胆固醇到雌激素的整个途径。本研究首次证明了无脊椎动物性类固醇产生过程中存在CYP酶。
