A relaxin-like peptide purified from radial nerves induces oocyte maturation and ovulation in the starfish, Asterina pectinifera
A relaxin-like peptide purified from radial nerves induces oocyte maturation and ovulation in the starfish, Asterina pectinifera
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DOI：
10.1073/pnas.0900243106
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发表时间：
2009-06-09
影响因子：
11.1
通讯作者：
Nagahama, Yoshitaka
中科院分区：
文献类型：
--
作者：
Mita, Masatoshi;Yoshikuni, Michiyasu;Nagahama, Yoshitaka
海星的性腺刺激物质（GSS）是唯一已知的负责最终配子成熟的无脊椎动物肽激素，其功能类似于脊椎动物的黄体生成素（LH）。本研究从海星的桡神经中纯化了GSS，并测定了其氨基酸序列。纯化的GSS是由2种不同的肽a链和B链组成的异源二聚体，具有二硫交键。基于其半胱氨酸基序，海星GSS被归类为胰岛素/胰岛素样生长因子(IGF)/松弛素超家族的成员。GSS的cDNA编码a链和B链之间有一个C肽的激素前原序列。系统发育分析表明，海星GSS是一种松弛素样肽。化学合成的GSS不仅在分离的卵巢碎片中诱导卵母细胞成熟和排卵，而且在注射后不久诱导独特的产卵行为，随后释放配子。重要的是，合成的GSS对卵母细胞成熟和排卵的作用是通过分离的卵巢卵泡细胞产生cAMP介导的，从而产生该物种的成熟诱导激素，1-甲基腺嘌呤。原位杂交显示，GSS的转录发生在管足侧桡神经周围。综上所述，GSS的结构、序列和信号转导方式强烈提示GSS与脊椎动物松弛素密切相关。
Gonad-stimulating substance (GSS) of starfish is the only known invertebrate peptide hormone responsible for final gamete maturation, rendering it functionally analogous to the vertebrate luteinizing hormone (LH). Here, we purified GSS of starfish, Asterina pectinifera, from radial nerves and determined its amino acid sequence. The purified GSS was a heterodimer composed of 2 different peptides, A and B chains, with disulfide cross-linkages. Based on its cysteine motif, starfish GSS was classified as a member of the insulin/insulin-like growth factor (IGF)/relaxin superfamily. The cDNA of GSS encodes a preprohormone sequence with a C peptide between the A and B chains. Phylogenetic analyses revealed that starfish GSS was a relaxin-like peptide. Chemically synthesized GSS induced not only oocyte maturation and ovulation in isolated ovarian fragments, but also unique spawning behavior, followed by release of gametes shortly after the injection. Importantly, the action of the synthetic GSS on oocyte maturation and ovulation was mediated through the production of cAMP by isolated ovarian follicle cells, thereby producing the maturation-inducing hormone of this species, 1-methyladenine. In situ hybridization showed the transcription of GSS to occur in the periphery of radial nerves at the side of tube feet. Together, the structure, sequence, and mode of signal transduction strongly suggest that GSS is closely related to the vertebrate relaxin.