Characterization of the GSDMA- and GSDME-mediated pyroptosis pathway in ducks

Pyroptosis is an inflammatory programmed cell death mediated by gasdermin (GSDM) proteins, playing an important role in both physiological and pathological processes. While humans and other mammals possess multiple functional GSDM members (GSDMA-E) that execute pyroptosis through their pore-forming N-terminal domains, the duck genome encodes only two active GSDM members (GSDMA and GSDME), indicating distinct regulatory mechanism of pyroptosis in avian species. However, the molecular basis of duck GSDM-mediated pyroptosis remain poorly understood. In this study, the tissue expression profile of duck GSDMA (duGSDMA) and GSDME (duGSDME) was systematically investigated for the first time. Then, the mechanism studies demonstrated that duGSDME undergoes proteolytic processing by duCASP-1/3/6/7/8, generating a ~ 30 kDa pyroptosis-inducing N-terminal fragment. Intriguingly, duGSDMA is specifically cleaved by duCASP-6/8 at a unique site, producing a distinct ~ 35kDa N-terminal fragment with pore-forming activity. To explore the physiological relevance of these findings, a monocyte-macrophage infection model was established using novel duck reovirus (NDRV). This model revealed a complex interaction between viral infection and pyroptotic signaling, demonstrating the the dual role of pyroptosis in both antiviral defense and immunopathology during viral infection. Collectively, this study demonstrates that the pyroptosis mechanism in ducks is significantly different from mammalian systems and provides a new insight for the pathogenic mechanism of duck infectious disease.