Wang Hongyan, Guang Wei, Barbier Elisabeth, Shapiro Paul, Wang Jia Bei
Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, USA.
Neuroreport. 2007 Dec 3;18(18):1969-73. doi: 10.1097/WNR.0b013e3282f228b2.
This study was to characterize the effects of a point-mutant at C-terminal of mu opioid receptor (MOR), namely MOR T394A, in chronic opioid-induced cellular responses. After 18 h of exposure to [D-Ala, N-Me-Phe, Gly-ol] enkephalin (DAMGO), adenylyl cyclase (AC) superactivation, a hallmark for the cellular adaptive response after chronic opioid stimulation, was observed in the cells expressing wild-type receptor, but was totally abolished in the cells expressing MOR T394A. Receptor phosphorylation was also attenuated in cells with MOR T394A after prolonged preexposure to agonist. Furthermore, MAP kinase kinase-1 (MKK1) overexpression was able to rescue AC superactivation in cells with MOR T394A, but showed no effect in the wild-type MOR-expressing cells. These results indicated that the amino acid T394 at C-terminus of MOR played a critical role in chronic agonist-induced AC superactivation and receptor phosphorylation.
本研究旨在表征μ阿片受体（MOR）C末端的一个点突变体，即MOR T394A，在慢性阿片类药物诱导的细胞反应中的作用。在用[D-丙氨酸，N-甲基苯丙氨酸，甘氨醇]脑啡肽（DAMGO）处理18小时后，在表达野生型受体的细胞中观察到腺苷酸环化酶（AC）超活化，这是慢性阿片类药物刺激后细胞适应性反应的一个标志，但在表达MOR T394A的细胞中完全消失。在长时间预暴露于激动剂后，MOR T394A细胞中的受体磷酸化也减弱。此外，丝裂原活化蛋白激酶激酶-1（MKK1）的过表达能够挽救MOR T394A细胞中的AC超活化，但对表达野生型MOR的细胞没有影响。这些结果表明，MOR C末端的氨基酸T394在慢性激动剂诱导的AC超活化和受体磷酸化中起关键作用。
