RIPK3 promotes neuronal survival by suppressing excitatory neurotransmission during CNS viral infection

While recent work has identified roles for cytokines and inflammation in the regulation of neural activity, the capacity for cell intrinsic innate immune signaling within neurons to influence neurotransmission remains poorly understood. However, the existing evidence linking immune signaling with neuronal activity suggests that modulation of neurotransmission may serve previously undefined roles in host protection and pathogen control within the central nervous system. Here, we identify a specialized function for RIPK3, a kinase traditionally associated with necroptotic cell death, in preserving neuronal survival during neurotropic flavivirus infection through the suppression of excitatory neurotransmission. We show that RIPK3 coordinates transcriptomic changes in neurons that suppress neuronal glutamate signaling, thereby desensitizing neurons to excitotoxic cell death. These effects occur independently of the traditional functions of RIPK3 in promoting MLKL-dependent necroptosis and NF?B-mediated inflammatory transcription. Instead, RIPK3 promotes phosphorylation of the key neural regulatory kinase CAMKII, which in turn activates the transcription factor CREB to drive a neuroprotective transcriptional program and suppress deleterious glutamatergic signaling. These findings identify an unexpected function for a canonical cell death protein in promoting neuronal survival during viral infection through the modulation of neuronal activity, highlighting new mechanisms of neuroimmune crosstalk. Overall design: We performed bulk RNA sequencing of primary cerebral cortical neurons derived from E15.5 embryos harboring a chemogenetically activatable verson of RIPK3 (RIPK3-2xFV) that can be activated with the drug B/B homodimerizer (B/B). Neurons were treated with B/B or vehicle solution in the presence of KN93 (CaMKII inhibitor), 666-15 (CREB inhibitor), or control solution for 24 hours prior to harvest.