Mechanism of Ca2+ Disruption in Alzheimer's Disease by Presenilin Regulation of InsP3 Receptor Channel Gating

Summary Mutations in presenilins (PS) are the major cause of familial Alzheimer's disease (FAD) and have been associated with calcium (Ca 2+ ) signaling abnormalities. Here, we demonstrate that FAD mutant PS1 (M146L) and PS2 (N141I) interact with the inositol 1,4,5-trisphosphate receptor (InsP 3 R) Ca 2+ release channel and exert profound stimulatory effects on its gating activity in response to saturating and suboptimal levels of InsP 3 . These interactions result in exaggerated cellular Ca 2+ signaling in response to agonist stimulation as well as enhanced low-level Ca 2+ signaling in unstimulated cells. Parallel studies in InsP 3 R-expressing and -deficient cells revealed that enhanced Ca 2+ release from the endoplasmic reticulum as a result of the specific interaction of PS1-M146L with the InsP 3 R stimulates amyloid beta processing, an important feature of AD pathology. These observations provide molecular insights into the "Ca 2+ dysregulation" hypothesis of AD pathogenesis and suggest novel targets for therapeutic intervention.