A presenilin-1 mutation causes Alzheimer disease without affecting Notch signaling

Presenilin-1 (PSEN1) is the catalytic subunit of the gamma-secretase complex, and pathogenic mutations in the PSEN1 gene account for the majority cases of familial AD (FAD). FAD-associated mutant PSEN1 proteins have been shown to affect APP processing and A beta generation and inhibit Notch1 cleavage and Notch signaling. In this report, we found that a PSEN1 mutation (S169del) altered APP processing and A beta generation, and promoted neuritic plaque formation as well as learning and memory deficits in AD model mice. However, this mutation did not affect Notch1 cleavage and Notch signaling in vitro and in vivo. Taken together, we demonstrated that PSEN1(S169del) has distinct effects on APP processing and Notch1 cleavage, suggesting that Notch signaling may not be critical for AD pathogenesis and serine169 could be a critical site as a potential target for the development of novel gamma-secretase modulators without affecting Notch1 cleavage to treat AD.