“DNA damage activates cGAS-STING signaling through ROS dependent p62 recruitment”

Abstract

Abstract Ionizing radiation (IR) induces DNA damage that activates innate immunity through the cyclic GMP–AMP synthase (cGAS) pathway, yet the mechanisms determining why only a subset of radiation-induced micronuclei (MNi) become cGAS-positive remain unclear. Here, we investigated the dose- and time-dependent dynamics of cGAS-positive MNi and the molecular events regulating their formation in HaCaT human keratinocytes. cGAS recruitment occurred with delayed kinetics relative to total MNi formation and was associated with micronuclear envelope destabilization and lamin B1 loss. Structural observations support a sequential model in which early recruitment of the autophagy receptor p62 precedes micronuclear envelope destabilization and subsequent cGAS recruitment. Reactive oxygen species (ROS) generated following irradiation emerged as key upstream regulators by promoting p62 recruitment and micronuclear destabilization. Accordingly, ROS scavenging with N-acetylcysteine markedly reduced both p62-positive and cGAS-positive MNi. Conditioned-medium experiments further demonstrated that diffusible ROS-dependent signals generated by irradiated cells promote the formation of cGAS-positive MNi in non-irradiated bystander cells. Finally, cGAS activation was accompanied by delayed induction of type I interferons and ISG15, which was attenuated by ROS scavenging. Together, these findings identify oxidative stress as a critical regulator linking radiation-induced genomic instability to innate immune activation through p62-dependent micronuclear sensing.