title: Activation of α7 nicotinic receptor affects APP processing by regulating secretase activity in SH-EP1-α7 nAChR-hAPP695 cells.
abstract: 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 α7 nAChR activation affects APP695 processing in SH-EP1 cell model. Cell line co-expressing α7 nAChR gene and human amyloid precursor protein 695 (hAPP695) gene were constructed by stable transfection. Expression of β-amyloid, α-form of secreted APP (αAPPs) and APP1695 was measured by ELISA, western blotting and real-time PCR respectively. Additionally, α, β, and γ-secretase activities were also analyzed in constructed SH-EP1-α7 nAChR-hAPP695 cell line. The results showed that SH-EP1-α7 nAChR-hAPP695 cell line, expressing both hAPP695 gene and α7 nAChR subtype gene, was constructed successfully. The secreted Aβ was decreased and αAPPs was significantly increased by non-selective nAChR agonist nicotine (10 μM) and specific α7 nAChR agonist GTS-21 (1 μM), and APP expression was not affected. Furthermore, specific α7 nAChR antagonist methyllycaconitine (MLA) reversed the alterations induced by activation of α7 nAChR. CTF-α was increased and CTF-γ was decreased when treated with nicotine (10 μM). In addition, the results of enymatic activity analysis showed that nicotine (1μM) and GTS-21 (0.1, 1 μM) decreased γ-secretase activity, but has no effects on α-secretase activity and β-secretase activity. Our findings demonstrate that, through regulating γ-secretase activity, α7 nAChR activation reduces APP processing in amyloidogenic pathway, and at the same time enhances APP processing in non-amyloidogenic pathway. The constructed SH-EP1-α7 nAChR-hAPP695 cell line might be useful for screening specific nAChR agonists against AD.
authors: School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China.
authors: Hui Zhen
authors: HZ
authors: Nie
authors: Sha
authors: S
authors: Shi
authors: Ronald J
authors: RJ
authors: Lukas
authors: Wen Juan
authors: WJ
authors: Zhao
authors: Yong Ning
authors: YN
authors: Sun
authors: Ming
authors: M
authors: Yin
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism* / Q000502:physiology; D016564:Amyloid beta-Protein Precursor / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D002460:Cell Line; D015536:Down-Regulation / Q000235:genetics; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D009474:Neurons / Q000201:enzymology / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics / Q000502:physiology; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D015854:Up-Regulation / Q000235:genetics; D064569:alpha7 Nicotinic Acetylcholine Receptor
chemical_list: D016564:Amyloid beta-Protein Precursor; C579167:Chrna7 protein, human; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D053829:Amyloid Precursor Protein Secretases