A novel role of CDK2 inhibition in restraining microglial overactivation

Neuroinflammation driven by microglial overactivation is a significant contributor across a diverse range of neurological disorders. While MEF2C mutations have been associated with a syndromic form of autism spectrum disorder (ASD) and various other neurological disorders in humans, the role of MEF2C as a key immune checkpoint to restrain microglial overactivation remains elusive. In this study, we established MEF2C-knockout (KO) induced microglia-like cells (iMGLs) via differentiation of corresponding human pluripotent stem cells, and subsequently treated with LPS, as a disease model of overactivated microglia. Through high-throughput screening, we identified BMS265246, a CDK2 inhibitor, which effectively normalized overactivated phenotypes in LPS-stimulated MEF2C-KO iMGLs, nearing levels seen in WT counterparts. Mechanistically, absence of MEF2C instigated a sequential cascade encompassing p21 downregulation, CDK2 activation, RB phosphorylation and degradation, and NF-κB p65 subunit nuclear translocation, thereby intensifying inflammatory responses. Remarkably, BMS265246 treatment significantly rectified microglial overactivation and ASD behavioral defects in both global and microglia-specific Mef2C heterozygous mice. Overall, our findings elucidate a novel protective mechanism governed by MEF2C, and unveil CDK2 as a promising therapeutic target for treating various diseases influenced by overactivated microglia with aberrant MEF2C expression and/or CDK2 activation. In this study, we established MEF2C-knockout (KO) induced microglia-like cells (iMGLs) via differentiation of corresponding human pluripotent stem cells, and subsequently treated with LPS, as a disease model of overactivated microglia. Our comprehensive analysis identified BMS265246 could rectify LPS-treated overactivated MEF2C KO iMGLs. We then performed gene expression profiling analysis using data obtained from RNAseq of WT and MEF2C KO iMGLs treated with vehicle (n=3) and LPS (n=2), and MEF2C KO iMGLs treated with BMS265246 (BMS) in the presence of LPS (n=2).