title: The overexpression of presenilin2 and Alzheimer's-disease-linked presenilin2 variants influences TRPC6-enhanced Ca2+ entry into HEK293 cells.
abstract: Mutations in the presenilin (PS) genes are linked to the development of early-onset Alzheimer's disease by a gain-of-function mechanism that alters proteolytic processing of the amyloid precursor protein (APP). Recent work indicates that Alzheimer's-disease-linked mutations in presenilin1 and presenilin2 attenuate calcium entry and augment calcium release from the endoplasmic reticulum (ER) in different cell types. However, the regulatory mechanisms underlying the altered profile of Ca(2+) signaling are unknown. 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. We show that transient coexpression of Alzheimer's-disease-linked presenilin2 mutants and TRPC6 in human embryonic kidney (HEK) 293T cells abolished agonist-induced TRPC6 activation without affecting agonist-induced endogenous Ca(2+) entry. The inhibitory effect of presenilin2 and the Alzheimer's-disease-linked presenilin2 variants was not due to an increase in amyloid beta-peptides in the medium. Despite the strong negative effect of the presenilin2 and Alzheimer's-disease-linked presenilin2 variants on agonist-induced TRPC6 activation, conformational coupling between inositol 1,4,5-trisphosphate receptor type 3 (IP(3)R3) and TRPC6 was unaffected. In cells coexpressing presenilin2 or the FAD-linked presenilin2 variants, Ca(2+) entry through TRPC6 could still be induced by direct activation of TRPC6 with 1-oleoyl-2-acetyl-sn-glycerol (OAG). Furthermore, transient coexpression of a loss-of-function PS2 mutant and TRPC6 in HEK293T cells enhanced angiotensin II (AngII)- and OAG-induced Ca(2+) entry. These results clearly indicate that presenilin2 influences TRPC6-mediated Ca(2+) entry into HEK293 cells.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, Université de Sherbrooke, 3001, 12e avenue Nord, Sherbrooke, Quebec, Canada J1H 5N4.
authors.forename: Christian B
authors.initials: CB
authors.lastname: Lessard
authors.forename: Marc P
authors.initials: MP
authors.lastname: Lussier
authors.forename: Sylvie
authors.initials: S
authors.lastname: Cayouette
authors.forename: Geneviève
authors.initials: G
authors.lastname: Bourque
authors.forename: Guylain
authors.initials: G
authors.lastname: Boulay
mesh_terms: D000544:Alzheimer Disease / Q000235:genetics / Q000378:metabolism*; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D010450:Endopeptidases / Q000235:genetics; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D053766:Presenilin-2; D050052:TRPC Cation Channels; D015854:Up-Regulation
chemical_list: D007473:Ion Channels; D008565:Membrane Proteins; C508861:PSEN2 protein, human; D053766:Presenilin-2; D050052:TRPC Cation Channels; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; D002118:Calcium