AMPK-PP1/PP2 axis regulates GSDMD-mediated pyroptosis via phosphorylation

Gasdermin D (GSDMD), the most important executor of pyroptosis, is activated through caspase cleavage to release the N-terminal fragment (GD-NT), which oligomerizes and forms pores in the plasma membrane to induce pyroptosis. We previously reported that AMP-activated protein kinase (AMPK) phosphorylates GD-NT, thereby inhibiting its cytolytic activity. Here, we further investigated the role of phosphorylation in GD-NT-mediated pyroptosis and found that the specific AMPK agonist A-769662 protected tumor cells from GD-NT-mediated pyroptosis and that metformin significantly reduced interleukin 1β (IL-1β) and IL-18 in the peritoneal fluid of lipopolysaccharide (LPS)-induced septic mice. Importantly, we identified PP1/PP2 as the key phosphatases that dephosphorylate GD-NT at Ser46. Treatment of cells with the phosphatase inhibitor okadaic acid (OA) significantly enhanced the phosphorylation of GD-NT and reduced GD-NT-mediated pyroptosis. Therefore, we conclude that the AMPK-PP1/PP2 axis is a regulatory mechanism in pyroptosis. Pharmacological targeting of AMPK-PP1/PP2 provides a potential strategy for pyroptosis-related diseases.