title: Presenilin is the molecular target of acidic γ-secretase modulators in living cells.
abstract: The intramembrane-cleaving protease γ-secretase catalyzes the last step in the generation of toxic amyloid-β (Aβ) peptides and is a principal therapeutic target in Alzheimer's disease. Both preclinical and clinical studies have demonstrated that inhibition of γ-secretase is associated with prohibitive side effects due to suppression of Notch processing and signaling. Potentially safer are γ-secretase modulators (GSMs), which are small molecules that selectively lower generation of the highly amyloidogenic Aβ42 peptides but spare Notch processing. GSMs with nanomolar potency and favorable pharmacological properties have been described, but the molecular mechanism of GSMs remains uncertain and both the substrate amyloid precursor protein (APP) and subunits of the γ-secretase complex have been proposed as the molecular target of GSMs. We have generated a potent photo-probe based on an acidic GSM that lowers Aβ42 generation with an IC(50) of 290 nM in cellular assays. By combining in vivo photo-crosslinking with affinity purification, we demonstrated that this probe binds the N-terminal fragment of presenilin (PSEN), the catalytic subunit of the γ-secretase complex, in living cells. Labeling was not observed for APP or any of the other γ-secretase subunits. Binding was readily competed by structurally divergent acidic and non-acidic GSMs suggesting a shared mode of action. These findings indicate that potent acidic GSMs target presenilin to modulate the enzymatic activity of the γ-secretase complex.
authors.affiliation: Department of Neuropathology, Heinrich-Heine-University, Duesseldorf, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Jumpertz
authors.forename: Andreas
authors.initials: A
authors.lastname: Rennhack
authors.forename: Julia
authors.initials: J
authors.lastname: Ness
authors.forename: Sandra
authors.initials: S
authors.lastname: Baches
authors.forename: Claus U
authors.initials: CU
authors.lastname: Pietrzik
authors.forename: Bruno
authors.initials: B
authors.lastname: Bulic
authors.forename: Sascha
authors.initials: S
authors.lastname: Weggen
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D016466:CHO Cells; D002477:Cells / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D008954:Models, Biological; D058990:Molecular Targeted Therapy; D053763:Presenilins / Q000037:antagonists & inhibitors* / Q000502:physiology*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D004791:Enzyme Inhibitors; D053763:Presenilins; D053829:Amyloid Precursor Protein Secretases