Activation of alpha 7 nicotinic receptor affects APP processing by regulating secretase activity in SH-EP1-alpha 7 nAChR-hAPP695 cells

作者：Nie, Hui Zhen; Shi, Sha; Lukas, Ronald J; Zhao, Wen Juan; Sun, Yong Ning^*; Yin, Ming

来源：Brain Research, 2010, 1356: 112-120.

DOI：10.1016/j.brainres.2010.07.110

• alpha 7 nicotinic receptor
• SH-EP1 cell line
• beta-amyloid
• alpha APPs
• Secretase activity

Multiple lines of evidence have implicated that nicotinic acetylcholine receptor (nAChR) may be an important therapeutic target for the treatment of Alzheimer's disease (AD). Although there are reports suggesting a link between alpha7 nAChR subtype and AD, there has been little report on the mechanism. The present study investigates whether and how alpha 7 nAChR activation affects APP695 processing in SH-EP1 cell model. Cell line co-expressing alpha 7 nAChR gene and human amyloid precursor protein 695 (hAPP695) gene were constructed by stable transfection. Expression of beta-amyloid, alpha-form of secreted APP (alpha APPs) and APP1695 was measured by ELISA, western blotting and real-time PCR respectively. Additionally, alpha, beta, and gamma-secretase activities were also analyzed in constructed SH-EP1-alpha 7 nAChR-hAPP695 cell line. The results showed that SH-EP1-alpha 7 nAChR-hAPP695 cell line, expressing both hAPP695 gene and alpha 7 nAChR subtype gene, was constructed successfully. The secreted A beta was decreased and alpha APPs was significantly increased by non-selective nAChR agonist nicotine (10 mu M) and specific alpha 7 nAChR agonist GTS-21 (1 mu M), and APP expression was not affected. Furthermore, specific alpha 7 nAChR antagonist methyllycaconitine (MLA) reversed the alterations induced by activation of alpha 7 nAChR. CTF-alpha was increased and CTF-gamma was decreased when treated with nicotine (10 mu M). In addition, the results of enymatic activity analysis showed that nicotine (1 mu M) and GTS-21 (0.1, 1 mu M) decreased gamma-secretase activity, but has no effects on a-secretase activity and beta-secretase activity. Our findings demonstrate that, through regulating gamma-secretase activity, alpha 7 nAChR activation reduces APP processing in amyloidogenic pathway, and at the same time enhances APP processing in non-amyloidogenic pathway. The constructed SH-EP1-alpha 7 nAChR-hAPP695 cell line might be useful for screening specific nAChR agonists against AD.

• 出版日期2010-10-14
• 单位上海交通大学