Department of Biochemistry, Showa University School of Medicine, 1-5-8, Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
Bioorganic Research Institute, Suntory Foundation for Life Sciences, 8-1-1 Seikadai, Seika-cho, Soraku-gun, Kyoto 619-0284, Japan.
Gen Comp Endocrinol. 2022 Nov 1;328:114107. doi: 10.1016/j.ygcen.2022.114107. Epub 2022 Aug 13.
In starfish, a relaxin-like gonad-stimulating peptide (RGP) is the gonadotropin responsible for final gamete maturation. RGP comprises two different peptides, A- and B-chains with two interchain and one intrachain disulfide bonds. The existence of two isomers of RGP in the crown-of-thorns starfish, Acanthaster planci, has been reported previously, but it was recently shown that A. planci represents a species complex with four different species. Here we elucidated the authentic sequence of the Pacific species, Acanthaster cf. solaris, RGP (Aso-RGP). The Aso-RGP precursor encoded by a 354 base pair open reading frame was composed of 117 amino acids (aa). The amino acid identity of Aso-RGP to Patiria pectinifera RGP (Ppe-RGP) and Asterias amurensis RGP (Aam-RGP) was 74% and 60%, respectively. Synthetic Aso-RGP induced spawning of ovarian fragments from A. cf. solaris. Ppe-RGP and Aam-RGP also induced spawning by A. cf. solaris ovaries. In contrast, Ppe-RGP and Aso-RGP induced spawning by P. pectinifera ovaries, but Aam-RGP was inactive. Notably, anti-Ppe-RGP antibodies recognized Aso-RGP as well as Ppe-RGP. Localization of Aso-RGP was observed immunohistochemically using anti-Ppe-RGP antibodies, showing that Aso-RGP was mainly present in the radial nerve cords of A. cf. solaris. Aso-RGP was distributed not only in the epithelium of the ectoneural region but also in the neuropile of the ectoneural region. These results suggest that Aso-RGP is synthesized in the epithelium of the ectoneural region, then transferred to fibers in the neuropile of the ectoneural region in radial nerve cords.
在海星中，一种松弛素样性腺刺激肽（RGP）是负责最终配子成熟的促性腺激素。RGP 由两个不同的肽，A-和 B-链组成，具有两个链间和一个链内二硫键。先前已经报道过棘冠海星（Acanthaster planci）中存在两种 RGP 异构体，但最近表明棘冠海星是一个具有四个不同物种的物种复合体。在这里，我们阐明了太平洋物种，太阳海星（Acanthaster cf. solaris）RGP（Aso-RGP）的真实序列。由 354 个碱基对开放阅读框编码的 Aso-RGP 前体由 117 个氨基酸（aa）组成。Aso-RGP 与 Paphia pectinifera RGP（Ppe-RGP）和 Asterias amurensis RGP（Aam-RGP）的氨基酸同一性分别为 74%和 60%。合成的 Aso-RGP 诱导了来自 A. cf. solaris 的卵巢片段产卵。Ppe-RGP 和 Aam-RGP 也通过 A. cf. solaris 卵巢诱导产卵。相比之下，Ppe-RGP 和 Aso-RGP 诱导了 P. pectinifera 的卵巢产卵，但 Aam-RGP 不起作用。值得注意的是，抗 Ppe-RGP 抗体识别 Aso-RGP 以及 Ppe-RGP。使用抗 Ppe-RGP 抗体进行免疫组织化学定位观察到 Aso-RGP 的定位，表明 Aso-RGP 主要存在于太阳海星的辐射神经索中。Aso-RGP 不仅分布在外神经区的上皮中，也分布在外神经区的神经丛中。这些结果表明 Aso-RGP 在外神经区的上皮中合成，然后转移到辐射神经索中神经丛的纤维中。
