Transcriptional Regulation of Microglial Metabolic and Activation States by P2RY12

Microglia are the resident immune cells of the CNS and integral to maintaining homeostasis. They rapidly respond to injury or infection within the CNS by altering their morphology, proliferating, and releasing cytokines and other signaling molecules. Microglia also play critical roles in development, regulating synaptic pruning and debris clearance. In disease, they are powerful mediators of neuroinflammation. Understanding the molecular pathways involved in microglial function is pivotal for advancing neurobiological research and developing effective strategies for CNS disorders. In this context, P2RY12 is a G protein-coupled receptor (GPCR) that is enriched in microglia in the brain parenchyma and is part of the transcriptional signature of homeostatic, ramified microglia. However, P2RY12 is downregulated in activated microglia and in neurological conditions. The downstream effects of P2RY12 downregulation in disease-associated microglia and how they influence microglial activation remain inadequately understood. In this study, we apply transcriptional and histological methods to explore the changes to microglia upon a genetic P2RY12 loss. Our findings reveal that P2RY12-deficient microglia experience alterations in distinct metabolic pathways while preserving overall homeostatic microglial transcriptional identity. P2RY12 deficiency dysregulates signature genes involved in homeostatic iron metabolism. Importantly, the Glutathione Peroxidase 4 (GPX4)-Glutathione (GSH) antioxidant pathway related to ferroptosis susceptibility is impaired upon microglial activation with LPS treatment. These results highlight the critical role of P2RY12 in regulating microglial immune and metabolic responses under both homeostatic and inflammatory conditions, providing insights into its involvement in CNS pathophysiology.