A dominant-negative human growth hormone-releasing hormone (GHRH) receptor splice variant inhibits GHRH binding.
A dominant-negative human growth hormone-releasing hormone (GHRH) receptor splice variant inhibits GHRH binding.
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DOI：
10.1210/en.2005-1488
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发表时间：
2006-04
期刊：
影响因子：
4.8
通讯作者：
A. McElvaine;K. Mayo
中科院分区：
文献类型：
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作者：
A. McElvaine;K. Mayo
GHRH 是一种下丘脑肽，可刺激垂体生长激素细胞合成和分泌 GH。 GHRH 受体是一种七跨膜 G 蛋白偶联受体，定位于生长激素细胞表面并结合 GHRH。 GHRH 受体初级转录物在外显子 11 的内含子/外显子边界 3' 处的选择性剪接导致包含通常为内含子的序列。在人类中，该内含物具有框内提前终止密码子，并且该变异 mRNA 编码在第六个跨膜结构域之前截短的蛋白质。为了确定截短受体对野生型受体信号传导的影响及其产生作用的机制，对全长和截短受体构建体进行表位标记并转染到 HeLa T4 细胞中以检查信号传导和表达。结果表明，截短的 GHRH 受体不能通过 cAMP 途径发出信号，而是作为野生型受体信号传导的主要抑制剂。野生型和截短的 GHRH 受体蛋白形成复合物。生成稳定转染的细胞系以检查截短受体的信号抑制机制。数据显示，当野生型和截短型受体共转染时，受体细胞表面表达没有改变，但截短型受体共表达显着降低了野生型受体对 GHRH 的结合。结果支持选择性剪接在介导 G 蛋白偶联受体的总体作用中发挥重要作用，并表明 GHRH 受体可以形成多聚体，这可能对其信号传导特性很重要。
GHRH is a hypothalamic peptide that stimulates the synthesis and secretion of GH from pituitary somatotroph cells. The GHRH receptor is a seven-transmembrane G protein-coupled receptor that localizes to the surface of somatotroph cells and binds GHRH. Alternative splicing of the GHRH receptor primary transcript at the intron/exon boundary 3' of exon 11 results in inclusion of sequence that is normally intronic. In the human, this inclusion has an in-frame premature stop codon, and this variant mRNA encodes a protein truncated just before the sixth transmembrane domain. To identify the effects of the truncated receptor on signaling of the wild-type receptor and the mechanisms by which its effects are produced, the full-length and truncated receptor constructs were epitope tagged and transfected into HeLa T4 cells to examine signaling and expression. Results show that the truncated GHRH receptor cannot signal through the cAMP pathway and acts as a dominant inhibitor of wild-type receptor signaling. The wild-type and truncated GHRH receptor proteins form a complex. Stably transfected cell lines were generated to examine the mechanism of signal inhibition by the truncated receptor. The data show that receptor cell surface expression is not altered when the wild-type and truncated receptors are cotransfected, but that truncated receptor coexpression substantially reduces GHRH binding by the wild-type receptor. The results support an important role for alternative splicing in mediating the effects of G protein-coupled receptors in general, and suggest that the GHRH receptor can form multimers, which may be important to its signaling properties.