title: Specific downregulation of presenilin 2 gene expression is prominent during early stages of sporadic late-onset Alzheimer's disease.
abstract: Mutations in the presenilin genes PS1 and PS2 cause familial Alzheimer's disease (AD). In a previous study, we reported that PS2 mRNA levels are decreased in the hippocampus, frontal cortex and basal forebrain of subjects with late-onset sporadic AD. In this study, we examined whether this downregulation occurs as the disease progresses from mild to severe stages or whether downregulation of PS2 expression is an early event in AD. We used in situ hybridization histochemistry to quantify the level of expression of PS2 message in the hippocampus of normal subjects and subjects with mild, moderate or severe AD. Several regions of the hippocampus which are sequentially susceptible to AD neuropathology as the disease progresses in severity were analyzed. We demonstrate that specific downregulation of PS2 expression is as severe in subjects with mild AD as it is in subjects in late stages of the disease. In addition, we show that hippocampal regions that are relatively free of AD neuropathology during early stages of the disease exhibit severely compromised PS2 mRNA levels even in mild AD cases. In contrast, PS2 is expressed at normal levels in the cerebellum, a region which succumbs to significantly fewer AD-related insults even at very advanced stages of the disease. These results suggest that the specific downregulation of PS2 gene expression is an early event in sporadic late-onset AD.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Box 356560, University of Washington, Seattle, WA 98195, USA. pammcm@u.washington.edu
authors.forename: P J
authors.initials: PJ
authors.lastname: McMillan
authors.forename: J B
authors.initials: JB
authors.lastname: Leverenz
authors.forename: D M
authors.initials: DM
authors.lastname: Dorsa
mesh_terms: D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000235:genetics* / Q000503:physiopathology*; D001923:Brain Chemistry / Q000235:genetics; D002531:Cerebellum / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D053766:Presenilin-2; D012333:RNA, Messenger / Q000032:analysis; D012720:Severity of Illness Index
chemical_list: D008565:Membrane Proteins; C508861:PSEN2 protein, human; D053766:Presenilin-2; D012333:RNA, Messenger