Novel Presenilin-1 Gene Mutation (N24S)and ITS Functional Impact On App Processing And Notch Signaling Pathway In Familial Alzheimer’s Disease

OBJECTIVE to investigate the functional impact of novel presenilin-lgene mutation (N24S) on APP processing and Notch signaling pathway, to explore the pathogenic contribution of this novel mutation for familial Alzheimer’s disease.METHODS We have sequenced the third exon of presenilin-1 gene of 105 patients with clinically confirmed sporadic Alzheimer’s disease and 107 healthy controls to test the polymorphism of A71 locus where the PS1 N24S mutation was detected via PCR amplification technique. then a cell line dual transfected by APP695swe and PS-N24S mutation gene was constructed based on mutated plasmid and its transfection into N2a-APP695 cells by lipofectamin 2000, the mutated plasmid was established by one step site-directed mutagenesis of wild type plasmid-pcDNA3.1/PS1 (WT) which expresses pcDNA3.1/PS1-N24S (A71G) mutation. The expression level of APP β, APPa in the supernatant of dual transfected cell line were determined by western blots and the level of A β test by ELISA.then the expression level of PS1, BACE-1, APP-CTFs, Notch and NICD were measured in the total protein extracts from the transfected cell line using western blots technique, the aim is to evaluate the functional impact of N24S mutation on APP processing and Notch signaling pathway.RESULT No psl-N24S mutation was found among 105 patients with sporadic Alzheimer’s disease and 107 healthy controls. Furthermore, in the dual transfected N2a-APP695/PS-N24S cell line, the level of BACE-1, APP β, APP-CTFs, A β 40 and A β 42 have significantly increased compared to the level of control group (P<0.05), whereas no statistical significance was found in comparison to E280A group (P>0.05). Besides, no difference in expression level was detected among all the groups in terms of Notch signaling pathway (P>0.05).CONCLUSIONS Novel PS1-N24S mutation can evidently increase the expression level of BACE-1, and further enhance APP processing by regulating the expression of APP β, APP-CTFs, A β 42, A β 40. Whereas PS1-N24S mutation might not have a role in Notch signaling pathway...