The Card19 locus regulates apoptosis and pyroptosis downstream of caspase activation and gasdermin D cleavage independently from IL-1 cytokine release

Cell death plays a critical role in inflammatory responses. During pyroptosis, inflammatory caspases cleave Gasdermin D (GSDMD) to release an N-terminal fragment that generates plasma membrane pores that mediate cell lysis and IL-1 release. However, certain stimuli and cell types release IL-1 cytokines through GSDMD pores in cells that remain viable, a process termed hyperactivation. How these distinct cell fate choices are regulated downstream of GSDMD pore formation is unknown. Here, we demonstrate that the Card19 locus promotes lysis downstream of caspase activation. Despite being largely protected from cell death, CARD19-deficient macrophages had no defect in caspase activation, IL-1 secretion, or GSDMD cleavage. CARD19, a mitochondrial protein, was not responsible for the observed phenotypes, nor was the recently identified pore forming protein NINJ1 which regulates terminal pore formation during multiple forms of cell death. Furthermore, previously identified cell death phenotypes attributed to Sterile alpha and heat Armadillo motif-containing protein (SARM) were revealed to be caused by a passenger mutation. Importantly, Card19-/ mice had increased susceptibility to Yersinia infection, including increased mortality, higher bacterial burdens and pronounced splenomegaly. These findings implicate the Card19 locus as a factor that couples caspase processing and GSDMD cleavage to cell death, providing insight into how the checkpoint between hyperactivation and cell death is regulated. Total 11 samples. Three technical replicates were analyzed for four groups (two genotypes, with or without LPS). Sample 7 was lost during processing and was not included in analysis.