title: BACE1 and BACE2 enzymatic activities in Alzheimer's disease.
abstract: beta-Secretase is the rate limiting enzymatic activity in the production of the amyloid-beta peptide (Abeta) and is thought to be involved in Alzheimer's disease (AD) pathogenesis. Although BACE1 (beta-site APP Cleaving Enzyme 1, EC 3.4.23.46) has received significant attention, the related BACE2 (EC 3.4.23.45) has not. Though BACE2 is also expressed in the brain, its potential role in AD has not been resolved. In this study, we compared the activities of both BACE1 and BACE2, which were isolated from the same samples of frontal cortex from both AD-affected individuals and age-matched controls. BACE1 activity showed a significant positive correlation with the amount of extractable Abeta, and BACE1 protein and activity were significantly increased in AD cases. Unexpectedly, there were substantial total amounts of BACE2 protein and enzymatic activity in the human brain. BACE2 activity did not change significantly in the AD brain, and was not related to Abeta concentration. These data indicate that BACE1 likely accounts for most of the Abeta produced in the human brain, and that BACE2 activity is not a likely contributor. However, as both forms of BACE compete for the same substrate pool, even small changes in BACE2 activity could have consequences for human disease.
authors.affiliation: Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, USA.
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Ahmed
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Holler
authors.forename: Robin L
authors.initials: RL
authors.lastname: Webb
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.forename: Tina L
authors.initials: TL
authors.lastname: Beckett
authors.forename: M Paul
authors.initials: MP
authors.lastname: Murphy
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000201:enzymology* / Q000473:pathology; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism*; D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism*; D001921:Brain / Q000201:enzymology*; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D047468:Immunoprecipitation; D007668:Kidney / Q000201:enzymology / Q000473:pathology; D008297:Male; D013223:Statistics as Topic; D013997:Time Factors
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D053829:Amyloid Precursor Protein Secretases; D016282:Aspartic Acid Endopeptidases; C509284:BACE2 protein, human; C509280:BACE1 protein, human