Abstract

Familial Alzheimer's disease (FAD) is caused by mutations in amyloid precursor protein and presenilins (PS1, PS2). Many FAD-linked PS mutations affect intracellular calcium (Ca2+) homeostasis by proximal mechanisms independent of amyloid production by dramatically enhancing gating of the inositol trisphosphate receptor (InsP3R) intracellular Ca2+ release channel by a gain-of-function effect that mirrors genetics of FAD and is independent of secretase activity. Electrophysiological recordings of InsP3R in FAD patient B cells, cortical neurons of asymptomatic PS1-AD mice, and other cells revealed they have higher occupancy in a high open probability burst mode, resulting in enhanced Ca2+ signaling. Exaggerated Ca2+ signaling through this mechanism results in enhanced generation of reactive oxygen species, believed to be an important component in AD pathogenesis. Exaggerated Ca2+ signaling through InsP3R–PS interaction is a disease specific and robust proximal mechanism in AD that may contribute to the pathology of AD by enhanced generation of reactive oxygen species.