RIPK1 activation in Mecp2-deficient microglia promotes inflammation and glutamate release in RTT

Rett syndrome (RTT) is a devastating neurodevelopmental disorder primarily caused by mutations in the methyl-CpG binding protein 2 (Mecp2) gene. Here, we found that inhibition of Receptor- Interacting Serine/Threonine- Protein Kinase 1 (RIPK1) kinase ameliorated progression of motor dysfunction after onset and prolonged the survival of Mecp2-null mice. Microglia were activated early in myeloid Mecp2- deficient mice, which was inhibited upon inactivation of RIPK1 kinase. RIPK1 inhibition in Mecp2- deficient microglia reduced oxidative stress, cytokines production and induction of SLC7A11, SLC38A1, and GLS, which mediate the release of glutamate. Mecp2- deficient microglia release high levels of glutamate to impair glutamate- mediated excitatory neurotransmission and promote increased levels of GluA1 and GluA2/3 proteins in vivo, which was reduced upon RIPK1 inhibition. Thus, activation of RIPK1 kinase in Mecp2- deficient microglia may be involved both in the onset and progression of RTT.