Mita Masatoshi, Nakamura Keitaro, Tsutsui Kazuyoshi, Katayama Hidekazu
Center for Advanced Biomedical Sciences, Research Institute for Science and Engineering, Waseda University, 2-2, Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan.
Department of Applied Biochemistry, School of Engineering, Tokai University, 4-1-1, Kitakaname, Hiratsuka, Kanagawa 259-1292, Japan.
Gen Comp Endocrinol. 2019 May 15;276:30-36. doi: 10.1016/j.ygcen.2019.02.019. Epub 2019 Feb 20.
A relaxin-like gonad-stimulating peptide (RGP) of starfish Patiria (Asterina) pectinifera is the first identified invertebrate gonadotropin for final gamete maturation. Recently, we found three orthologs of RGP in the class Asteroida; PpeRGP in P. pectinifera, AamRGP in Asterias amurensis, and AjaRGP in Aphelasterias japonica. In this study, nine kinds of RGP derivatives with exchanged each A- and B-chain were synthesized chemically to analyze the interaction of RGP with its receptor. Among these RGP derivatives, PpeRGP and its chimeric RGPs with B-chains from AamRGP or AjaRGP could induce oocyte maturation and ovulation in P. pectinifera ovaries. In contrast, other RGP derivatives were failed to induce spawning in P. pectinifera ovaries. Circular dichroism spectra of PpeRGP were similar to those of chimeric RGPs with the B-chains from AamRGP or AjaRGP. Furthermore, the predicted three-dimensional structure models of the B-chains from RGP derivatives have almost the same conformation. These findings suggest that the B-chain of PpeRGP is involved in binding to its receptor. Thus, it is likely that the A-chain of AamRGP or AjaRGP disturbs the binding of the PpeRGP B-chain to its receptor.
海星多棘海盘车（Asterina）pectinifera的一种类松弛素促性腺肽（RGP）是首个被鉴定出的用于最终配子成熟的无脊椎动物促性腺激素。最近，我们在海盘车纲中发现了RGP的三个直系同源物：多棘海盘车中的PpeRGP、 日本海盘车中的AjaRGP和 阿氏海盘车中的AamRGP。在本研究中，我们化学合成了九种A链和B链相互交换的RGP衍生物，以分析RGP与其受体的相互作用。在这些RGP衍生物中，PpeRGP及其带有来自AamRGP或AjaRGP的B链的嵌合RGP能够诱导多棘海盘车卵巢中的卵母细胞成熟和排卵。相比之下，其他RGP衍生物未能诱导多棘海盘车卵巢产卵。PpeRGP的圆二色光谱与带有来自AamRGP或AjaRGP的B链的嵌合RGP相似。此外，RGP衍生物B链的预测三维结构模型具有几乎相同的构象。这些发现表明，PpeRGP的B链参与与其受体的结合。因此，AamRGP或AjaRGP的A链可能会干扰PpeRGP B链与其受体的结合。
