咪唑啉Ⅰ型受体候选蛋白——非G蛋白偶联受体信号转导与ERK相关

Imidazoline-1 receptor candidate protein is not GPCR and its signal t ransduction pathway related to ERK

目的:研究在咪唑啉Ⅰ型受体(imidazoline-1receptor,I1R)激动剂莫索尼定和利美尼定作用下,I1R抗体选择性蛋白(imidazolinereceptorantiseraselectedprotein,IRAS)的信号转导机制。方法:采用[35S]-GTPγS结合实验,确定IRAS是否与G蛋白相偶联;采用蛋白免疫印迹方法,研究IRAS的激活与ERK磷酸化之间的关系。结果:以稳定表达有IRAS的CHO细胞(CHO-IRAS)为实验对象研究发现,利美尼定、莫索尼定在多种实验条件下均不能提高[35S]-GTPγS结合量,表明IRAS不与G蛋白偶联,而利美尼定和莫索尼定在激活IRAS的同时,能够浓度依赖性地显著升高ERK磷酸水平,其刺激作用能被I1R拮抗剂依法克生完全拮抗。结论:IRAS不与G蛋白偶联,ERK可能是IRAS偶联的信号分子之一。

Objective： To study the signal transduction mechanism（s） of imidazoline-1 receptor （I1R） candidate protein （IRAS） by the observation on the effects of I1R agonists moxonidine and rilmenidine. Methods： [^35 S]-GTPγS binding assay was carried out to determine whether G protein was involved in the signal transduction pathway of IRAS. Western blotting assay was used to study the relationship between IRAS and ERK phosphorylation in the experiment. Results： Rilmenidine and moxonidine were not able to simulate [^35S]-GTPγS binding in CHO-IRAS under different assay conditions, suggesting that IRAS was not coupled to GPCR. Rilmenidine and moxonidine could concentration-dependently increase the phosphorylation level of ERK by activation of IRAS, which was able to be reversed by efaroxan, a selective I1R antagonist. Conclusion： IRAS might not be a GPCR and ERK might be a signal transduction molecule of IRAS.