Presenilin-1 and-2 are molecular targets for γ-secretase inhibitors

Presenilins are integral membrane protein involved in the production of amyloid beta -protein, Mutations of the presenilin-1 and -2 gene are associated with familial Alzheimer's disease and are thought to alter gamma -secretase cleavage of the beta -amyloid precursor protein, leading to increased production of longer and more amyloidogenic forms of A beta, the 4-kDa beta -peptide, Here, we show that radiolabeled gamma -secretase inhibitors bind to mammalian cell membranes, and a benzophenone analog specifically photocross-links three major membrane polypeptides. A positive correlation is observed among these compounds for inhibition of cellular A beta formation, inhibition of membrane binding and cross-linking. Immunological techniques establish N- and C-terminal fragments of presenilin-1 as specifically cross-linked polypeptides, Furthermore, binding of gamma -secretase inhibitors to embryonic membranes derived fi om presenilin-1 knockout embryos is reduced in a gene dose-dependent manner. In addition, C-terminal fragments of presenilin-2 are specifically cross-linked. Taken together, these results indicate that potent and selective gamma -secretase inhibitors block A beta formation by binding to presenilin-1 and -2.