Proteolytic processing of the Alzheimer's disease amyloid precursor protein in brain and platelets.
Proteolytic processing of the amyloid precursor protein by beta -and gamma-secretases results in the production of Alzheimer's disease (AD) Abeta amyloid peptides. Modulation of secretase activity is being investigated as a potential therapeutic approach. Recent studies with human brain have revealed that the beta-secretase protein, BACE, is increased in cortex of AD patients. Analysis of betaCTF (or C99), the amyloid precursor protein (APP) product of BACE cleavage that is the direct precursor to Abeta, shows it is also elevated in AD, underlying the importance of beta-secretase cleavage in AD pathogenesis. The C-terminal product of gamma-secretase cleavage of APP, epsilonCTF (or AICD), is enriched in human brain cortical nuclear fractions, a subcellular distribution appropriate for a putative involvement of APP cytosolic domain in signal transduction. Analysis of AD cortex samples, particularly that of a carrier of a familial APP mutation, suggests that processing of APP transmembrane domain generates an alternative CTF product. All these particularities observed in the AD brain demonstrate that APP processing is altered in AD. The transgenic mouse model Tg2576 seems to be a promising laboratory tool to test potential modulators of Abeta formation. Indeed, C-terminal products of alpha-, beta-, and gamma-secretase cleavage are readily detectable in the brain of these transgenic mice. Finally, the finding of the same secretase products in platelets and neurons make platelets a potentially useful and easily accessible clinical tool to monitor effects of novel therapies based on inhibition of beta- or gamma-secretase.
Department of Pathology, University of Melbourne, Parkville, Australia. gmevin@unimelb.edu.au
Geneviève
G
Evin
Aiqin
A
Zhu
R M Damian
RM
Holsinger
Colin L
CL
Masters
Qiao-Xin
QX
Li
D000544:Alzheimer Disease / Q000378:metabolism*; D053829:Amyloid Precursor Protein Secretases; D016229:Amyloid beta-Peptides / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D016282:Aspartic Acid Endopeptidases; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D010450:Endopeptidases / Q000145:classification / Q000378:metabolism*; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D010446:Peptide Fragments / Q000378:metabolism; D053764:Presenilin-1; D053766:Presenilin-2; D013917:Thrombin / Q000494:pharmacology
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D006490:Hemostatics; D008565:Membrane Proteins; C508853:PSEN1 protein, human; C508861:PSEN2 protein, human; D010446:Peptide Fragments; D053764:Presenilin-1; D053766:Presenilin-2; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D013917:Thrombin; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human; C509282:Bace1 protein, mouse