Six novel gonadotropin-releasing hormones are encoded as triplets on each of two genes in the protochordate, Ciona intestinalis
Six novel gonadotropin-releasing hormones are encoded as triplets on each of two genes in the protochordate, Ciona intestinalis
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DOI：
10.1210/en.2002-0216
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发表时间：
2003-05-01
期刊：
影响因子：
4.8
通讯作者：
Sherwood, NM
中科院分区：
文献类型：
--
作者：
Adams, BA;Tello, JA;Sherwood, NM
GnRH是脊椎动物生殖轴的关键调节因子，但在脊椎动物起源之前，人们对GnRH知之甚少。我们已经确定了两个基因编码GnRH的原脊索动物，玻璃海鞘，被认为是有关的祖先动物，产生了脊椎动物。每个基因Ci-gnrh 1和Ci-gnrh 2串联编码三种GnRH肽，与已知形式相比，每种都是独特的。Ci-gnrh 1编码三个肽，不含内含子，而Ci-gnrh 2编码三个肽，但有两个内含子。这是第一个报告，其中一个以上的GnRH肽编码的一个基因。与人GNRH 1相比，玻璃海鞘基因具有保守的启动子序列。在四细胞期、原肠胚形成期、尾部释放期和尾部再吸收期，两种被囊动物基因均以mRNA形式表达。在一个与被囊类动物关系密切的物种，赛维氏玻璃海鞘中，我们使用计算机分析鉴定了两个编码六个肽的相似基因，其中只有一个与C.免疫组织化学显示，至少有一个GnRH肽是在神经网周围的背链。七种新的被囊动物肽的合成形式诱导了成年被囊动物配子的释放。与此相反，在大鼠垂体细胞试验中，这些肽不激活人GnRH-I受体或引起LH释放。这些数据提供了深入了解GnRH肽及其基因的结构进化，并显示了GnRH在被囊动物产卵中的功能作用。
GnRH is the key regulator of the reproductive axis in vertebrates, but little is known about GnRH before the origin of vertebrates. We have identified two genes encoding GnRH in a protochordate, Ciona intestinalis, thought to be related to the ancestral animal that gave rise to vertebrates. Each gene, Ci-gnrh1 and Ci-gnrh2, encodes in tandem three GnRH peptides, each of which is unique compared with known forms. Ci-gnrh1 encodes three peptides and contains no introns, whereas Ci-gnrh2 encodes three more peptides but has two introns. This is the first report in which more than one GnRH peptide is encoded on a single gene. The Ciona genes reveal consensus promoter elements that are conserved compared with human GNRH1.Both tunicate genes are expressed as mRNA early and throughout development, measured at the stages of four-cell, gastrulation, tail release, and tail resorption. In a closely related tunicate species, Ciona savignyi, we used in silico analysis to identify two similar genes encoding six peptides, only one of which is unique compared with C. intestinalis.Immunohistochemistry showed that at least one GnRH peptide was in the nerve net that surrounds the dorsal strand. Synthetic forms of the seven novel tunicate peptides induced release of gametes in adult tunicates. In contrast, the peptides did not activate the human GnRH-I receptor or cause release of LH in a rat pituitary cell assay. These data provide insight into the structural evolution of the GnRH peptides and their genes and show a functional role for GnRH in tunicate spawning.