Cloning and functional identification of novel endothelin receptor type A isoforms in pituitary
Cloning and functional identification of novel endothelin receptor type A isoforms in pituitary
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DOI：
10.1210/me.2006-0343
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发表时间：
2007-05-01
影响因子：
--
通讯作者：
Stojilkovic, Stanko S.
中科院分区：
文献类型：
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作者：
Hatae, Noriyuki;Aksentijevich, Nadia;Stojilkovic, Stanko S.
哺乳动物内皮素（ET）受体，称为ETAR和ETBR，来自两个含内含子的基因，ETBR的功能剪接变体，而不是ETAR已被确定。在这里，我们报告的ETAR转录从大鼠垂体前叶，这是由选择性RNA剪接产生的cDNA的分离。外显子2的缺失和内含子1和2片段的插入导致了三种错位蛋白的形成，而内含子6片段的插入导致了功能性质膜受体ETAR-C13的产生。在这种剪接变体中，ETAR的C-末端382 S-426 N序列被较短的382 A-399 L序列取代，导致负责偶联G（q/11）和G（s）蛋白和胞吞再循环的推定结构域改变，以及预测的蛋白激酶C/酪蛋白激酶2磷酸化位点缺失。在正常和永生化垂体细胞和几种其他组织中鉴定了ETAR-C13的mRNA转录物。重组ETAR和ETAR-C13的药理学特征高度相似，但ETAR-C13与钙动员信号通路的偶联减弱，导致激动剂效力的显著变化。此外，ETAR-C13刺激腺苷酸环化酶信号通路和内化的功效显著降低。这些结果首次表明存在一种新的ETA剪接受体，这可能有助于分泌型垂体细胞类型之间的功能异质性。
Mammalian endothelin (ET) receptors, termed ETAR and ETBR, are derived from two intron-containing genes and the functional splice variants of ETBR but not ETAR have been identified. Here, we report about the isolation of cDNAs of ETAR transcripts from rat anterior pituitary, which are generated by alternative RNA splicing. Deletion of exon 2 and insertion of fragments from intron 1 and 2 accounted for formation of three misplaced proteins, whereas the insertion of a fragment from intron 6 resulted in generation of a functional plasma membrane receptor, termed ETAR-C13. In this splice variant, the C-terminal 382S-426N sequence of ETAR was substituted with a shorter 382A-399L sequence, resulting in alteration of the putative domains responsible for coupling to G(q/11) and G(s) proteins and the endocytotic recycling, as well as in deletion of the predicted protein kinase C/casein kinase 2 phosphorylation sites. The mRNA transcripts for ETAR-C13 were identified in normal and immortalized pituitary cells and several other tissues. The pharmacological profiles of recombinant ETAR and ETAR-C13 were highly comparable, but the coupling of ETAR-C13 to the calcium-mobilizing signaling pathway was attenuated, causing a rightward shift in the potency for agonist. Furthermore, the efficacy of ETAR-C13 to stimulate adenylyl cyclase signaling pathway and to internalize was significantly reduced. These results indicate for the first time the presence of a novel ETA splice receptor, which could contribute to the functional heterogeneity among secretory pituitary cell types.