title: A comparative assessment of gamma-secretase activity in transgenic and non-transgenic rodent brain.
abstract: Amyloid-beta (Abeta) deposits are one of the hallmarks of the neuropathological degeneration observed in Alzheimer's disease (AD) and Abeta concentrations have been reported to vary in different brain regions of AD patients. Abeta is produced by the sequential cleavage of amyloid precursor protein (APP) by beta-secretase and gamma-secretase, respectively. Previous studies have shown that over-expression of the gamma-secretase complex leads to increased gamma-secretase proteolytic activity increasing Abeta production. However, it is not known whether brain regions with highest Abeta concentration also express relatively higher levels of gamma-secretase activity. Accordingly, the relationship between Abeta levels and gamma-secretase activity across brain regions was investigated and correlated in the brains of transgenic and non-transgenic rodents commonly used in AD research. The data demonstrated that Abeta levels do vary in different brain regions in both transgenic and non-transgenic mice but are not correlated with regional gamma-secretase activity. Furthermore, this study demonstrated that while mutations in the APP and PS1 sequences affect the absolute Abeta levels this is not reflected in an increase in gamma-secretase proteolytic activity. The data in the current paper indicate that this assay is able to measure the level of gamma-secretase activity in rodent species. Using this methodology will aid our understanding of physiological gamma-secretase function.
authors.affiliation: Department of In Vivo Neuroscience, The Neuroscience Research Centre, Merck Sharp and Dohme Research Laboratories, Essex CM20 2QR, UK.
authors.forename: Julian L
authors.initials: JL
authors.lastname: Goggi
authors.forename: Huw D
authors.initials: HD
authors.lastname: Lewis
authors.forename: Joanie
authors.initials: J
authors.lastname: Mok
authors.forename: Tim
authors.initials: T
authors.lastname: Harrison
authors.forename: Mark S
authors.initials: MS
authors.lastname: Shearman
authors.forename: John R
authors.initials: JR
authors.lastname: Atack
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Best
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000032:analysis* / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000032:analysis* / Q000378:metabolism*; D000818:Animals; D030801:Animals, Genetically Modified; D001921:Brain / Q000201:enzymology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016229:Amyloid beta-Peptides; D053829:Amyloid Precursor Protein Secretases