Substrate-targeting gamma-secretase modulators.
Selective lowering of Abeta42 levels (the 42-residue isoform of the amyloid-beta peptide) with small-molecule gamma-secretase modulators (GSMs), such as some non-steroidal anti-inflammatory drugs, is a promising therapeutic approach for Alzheimer's disease. To identify the target of these agents we developed biotinylated photoactivatable GSMs. GSM photoprobes did not label the core proteins of the gamma-secretase complex, but instead labelled the beta-amyloid precursor protein (APP), APP carboxy-terminal fragments and amyloid-beta peptide in human neuroglioma H4 cells. Substrate labelling was competed by other GSMs, and labelling of an APP gamma-secretase substrate was more efficient than a Notch substrate. GSM interaction was localized to residues 28-36 of amyloid-beta, a region critical for aggregation. We also demonstrate that compounds known to interact with this region of amyloid-beta act as GSMs, and some GSMs alter the production of cell-derived amyloid-beta oligomers. Furthermore, mutation of the GSM binding site in the APP alters the sensitivity of the substrate to GSMs. These findings indicate that substrate targeting by GSMs mechanistically links two therapeutic actions: alteration in Abeta42 production and inhibition of amyloid-beta aggregation, which may synergistically reduce amyloid-beta deposition in Alzheimer's disease. These data also demonstrate the existence and feasibility of 'substrate targeting' by small-molecule effectors of proteolytic enzymes, which if generally applicable may significantly broaden the current notion of 'druggable' targets.
Kukar
Thomas L
TL
Department of Neuroscience, Mayo Clinic, Mayo Clinic College of Medicine, 4500 San Pablo Road, Jacksonville, Florida 32224, USA. kukar.thomas@mayo.edu
Ladd
Thomas B
TB
Bann
Maralyssa A
MA
Fraering
Patrick C
PC
Narlawar
Rajeshwar
R
Maharvi
Ghulam M
GM
Healy
Brent
B
Chapman
Robert
R
Welzel
Alfred T
AT
Price
Robert W
RW
Moore
Brenda
B
Rangachari
Vijayaraghavan
V
Cusack
Bernadette
B
Eriksen
Jason
J
Jansen-West
Karen
K
Verbeeck
Christophe
C
Yager
Debra
D
Eckman
Christopher
C
Ye
Wenjuan
W
Sagi
Sarah
S
Cottrell
Barbara A
BA
Torpey
Justin
J
Rosenberry
Terrone L
TL
Fauq
Abdul
A
Wolfe
Michael S
MS
Schmidt
Boris
B
Walsh
Dominic M
DM
Koo
Edward H
EH
Golde
Todd E
TE
D000544:Alzheimer Disease / Q000188:drug therapy / Q000201:enzymology / Q000378:metabolism; D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D016564:Amyloid beta-Protein Precursor / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D001665:Binding Sites / Q000187:drug effects; D016466:CHO Cells; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D006801:Humans; D051379:Mice; D011485:Protein Binding / Q000187:drug effects; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity / Q000187:drug effects
D016564:Amyloid beta-Protein Precursor; D000894:Anti-Inflammatory Agents, Non-Steroidal; D051880:Receptors, Notch; D053829:Amyloid Precursor Protein Secretases