Zα2 domain of ZBP1 is a molecular switch regulating Influenza-induced PANoptosis and perinatal lethality during development

ABSTRACT Z-DNA-binding protein 1 (ZBP1) is an innate nucleic acid sensor which regulates host defense responses and development. ZBP1 activation triggers inflammation and pyroptosis, necroptosis, and apoptosis (PANoptosis) by activating RIPK3, caspase-8, and the NLRP3 inflammasome. ZBP1 is unique among innate sensors because of its N-terminal Zα1 and Zα2 domains, which bind to nucleic acids in the Z-conformation. However, the specific role of these Zα domains in orchestrating ZBP1 activation and subsequent inflammation and cell death is not clear. Here we have generated Zbp1 Δ Z α2/Δ Z α2 mice that lack the Zα2 domain of ZBP1 and demonstrate that this domain is critical for influenza A virus (IAV)-induced PANoptosis and perinatal lethality in RIPK1-RHIM mutated ( Ripk1 RHIM/RHIM ) mice. Deletion of the Zα2 domain in ZBP1 abolished IAV-induced PANoptosis and NLRP3 inflammasome activation. Furthermore, deletion of the Zα2 domain of ZBP1 was sufficient to rescue Ripk1 RHIM/RHIM mice from the perinatal lethality which is caused by ZBP1-driven cell death and inflammation. Our findings identify the essential role of the Zα2 domain of ZBP1 in physiological functions and establish a link between sensing of Z-RNAs via the Zα2 domain and the promotion of influenza-induced PANoptosis and perinatal lethality.