Presenilin 1 phosphorylation regulates amyloid-beta degradation by microglia

Amyloid-beta peptide (A beta) accumulation in the brain is a hallmark of Alzheimer's Disease. An important mechanism of A beta clearance in the brain is uptake and degradation by microglia. Presenilin 1 (PS1) is the catalytic subunit of gamma-secretase, an enzyme complex responsible for the maturation of multiple substrates, such as A beta. Although PS1 has been extensively studied in neurons, the role of PS1 in microglia is incompletely understood. Here we report that microglia containing phospho-deficient mutant PS1 display a slower kinetic response to micro injury in the brain in vivo and the inability to degrade A beta oligomers due to a phagolysosome dysfunction. An Alzheimer's mouse model containing phospho-deficient PS1 show severe A beta accumulation in microglia as well as the postsynaptic protein PSD95. Our results demonstrate a novel mechanism by which PS1 modulates microglial function and contributes to Alzheimer's -associated phenotypes.