The present study investigated the influence of two familial Alzheimer's-disease-linked presenilin2 variants (N141I and M239V) and a loss-of-function presenilin2 mutant (D263A) on the activity of the transient receptor potential canonical (TRPC)6 Ca(2+) entry channel.
A novel factor, termed Humanin (HN), antagonizes against neurotoxicity by various types of familial Alzheimer's disease (AD) genes [V642I and K595N/M596L (NL) mutants of amyloid precursor protein (APP), M146L-presenilin (PS) 1, and N141I-PS2] and by Abeta1-43 with clear action specificity ineffective on neurotoxicity by polyglutamine repeat Q79 or superoxide dismutase 1 mutants.
Functional analysis of such cleavage defective PS2 carrying the FAD mutation Asn-141 --> Ile showed that its Abeta42 producing activity was strongly reduced compared with cleavage-competent FAD PS2.
These results strongly suggest that the PS2 mutation (N141I) linked to FAD alters the metabolism of A beta/betaAPP to foster the production of the form of A beta that most readily deposits in amyloid plaques.