APP substitutions V715F and L720P alter PS1 conformation and differentially affect Abeta and AICD generation.
The 37-43 amino acid Abeta peptide is the principal component of beta-amyloid deposits in Alzheimer's disease (AD) brain, and is derived by serial proteolysis of the amyloid precursor protein (APP) by beta- and gamma-secretase. gamma-Secretase also cleaves APP at Val50 in the Abeta numbering (epsilon cleavage), resulting in the release of a fragment called APP intracellular domain (AICD). The aim of this study was to determine whether amino acid substitutions in the APP transmembrane domain differentially affect Abeta and AICD generation. We found that the APPV715F substitution, which has been previously shown to dramatically decrease Abeta40 and Abeta42 while increasing Abeta38 levels, does not affect in vitro generation of AICD. Furthermore, we found that the APPL720P substitution, which has been previously shown to prevent in vitro generation of AICD, completely prevents Abeta generation. Using a fluorescence resonance energy transfer (FRET) method, we next found that both the APPV715F and APPL720P substitutions significantly increase the distance between the N- and C-terminus of presenilin 1 (PS1), which has been proposed to contain the catalytic site of gamma-secretase. In conclusion, both APPV715F and APPL720P change PS1 conformation with differential effects on Abeta and AICD production.
Tesco
Giuseppina
G
Genetics and Aging Research Unit, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Charlestown, Massachusetts 02129-4404, USA.
Ginestroni
Andrea
A
Hiltunen
Mikko
M
Kim
Minji
M
Dolios
Georgia
G
Hyman
Bradley T
BT
Wang
Rong
R
Berezovska
Oksana
O
Tanzi
Rudolph E
RE
D019943:Amino Acid Substitution; D016229:Amyloid beta-Peptides / Q000096:biosynthesis*; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D017077:Culture Media, Conditioned; D004734:Energy Metabolism / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D016297:Mutagenesis, Site-Directed; D053764:Presenilin-1; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000378:metabolism
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D017077:Culture Media, Conditioned; D008565:Membrane Proteins; C508853:PSEN1 protein, human; D053764:Presenilin-1; D011956:Receptors, Cell Surface