Microglial RUNX1/RBM47 ablation inhibits neuronal ferroptosis via regulating the cGAS-STING-MEF2C pathway in mice with postoperative cognitive dysfunction

Activation of the cGAS-STING pathway has been proposed as a potential pathogenic mechanism underlying postoperative cognitive dysfuncton (POCD). Analysis of public transcriptomic data from the hippocampus of male mice suggests upregulation of Rbm47 in an experimental POCD model. In vitro, knockdown (KD) of Rbm47 in BV2 cells reduces levels of cGAS, STING, TNF-α, IL-6, and IFN-β under isoflurane and lipopolysaccharide (Iso + LPS) conditions. HT22 cells exposed to culture medium from Rbm47-KD BV2 cells treated with Iso + LPS show increased levels of MEF2C, GPX4, GSH, and SOD, and reduced levels of MDA and iron. Microglial Rbm47 overexpression amplifies cGAS-STING signaling and aggravates neuronal ferroptosis, which is reversed by the cGAS inhibitor RU.521. Rbm47 KD combined with RU.521 treatment synergistically ameliorates POCD in male mice. Mechanistically, the RRM2 domain of RBM47 interacts with the 3'UTR of cGAS mRNA, enhancing its stability. RUNX1 directly binds to the Rbm47 promoter and facilitates its transcription. RUNX1 overexpression activates the RBM47-cGAS-STING axis and exacerbates neuronal ferroptosis. Conversely, RUNX1 ablation ameliorates POCD, dampens the cGAS-STING signaling, and inhibits ferroptosis, which is abolished by RBM47 depletion. Our findings suggest that repression of RUNX1/RBM47 may represent a promising therapeutic strategy for POCD.