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

Presenilins are integral membrane protein involved in the production of amy loid beta -protein, Mutations of the presenilin-1 and -2 gene are associate d with familial Alzheimer's disease and are thought to alter gamma -secreta se cleavage of the beta -amyloid precursor protein, leading to increased pr oduction of longer and more amyloidogenic forms of A beta, the 4-kDa beta - peptide, Here, we show that radiolabeled gamma -secretase inhibitors bind t o mammalian cell membranes, and a benzophenone analog specifically photocro ss-links three major membrane polypeptides. A positive correlation is obser ved among these compounds for inhibition of cellular A beta formation, inhi bition of membrane binding and cross-linking. Immunological techniques esta blish N- and C-terminal fragments of presenilin-1 as specifically cross-lin ked polypeptides, Furthermore, binding of gamma -secretase inhibitors to em bryonic membranes derived fi om presenilin-1 knockout embryos is reduced in a gene dose-dependent manner. In addition, C-terminal fragments of preseni lin-2 are specifically cross-linked. Taken together, these results indicate that potent and selective gamma -secretase inhibitors block A beta formati on by binding to presenilin-1 and -2.