DSCR1 deficiency ameliorates the Aß pathology of Alzheimer's disease by enhancing microglial activity.

Microglial phagocytosis and clearance are important for the removal of amyloid-ß (Aß) plaques in Alzheimer's disease (AD). Chronic exposure of microglia to Aß plaques leads to microglial metabolic dysfunction, and dysregulation of microglia can accelerate the deposition of Aß plaques and cause learning and memory impairment. Thus, regulating microglial Aß clearance is crucial for the development of therapeutics for AD-related dementia. Here, Down syndrome critical region 1 (DSCR1) deficiency ameliorated Aß plaque deposition in the 5xFAD mouse model of AD by altering microglial activity; however, the Aß synthesis pathway was not affected. DSCR1 deficiency improved spatial learning and memory impairment in 5xFAD mice. Furthermore, DSCR1-deficient microglia exhibited accelerated lysosomal degradation of Aß after phagocytosis, and BV2 cells with stable knockdown of DSCR1 demonstrated enhanced lysosomal activity. RNA-sequencing analysis showed that the transcriptional signatures associated with responses to IFN-γ were significantly up-regulated in DSCR1-knockdown BV2 cells treated with Aß. Our data strongly suggest that DSCR1 is a critical mediator of microglial degradation of amyloid plaques and a new potential microglial therapeutic target in AD.