PBLD promotes virus-induced pyroptosis via NF-κB/Caspase-3/GSDME signaling pathway

Phenazine biosynthesis-like domain-containing protein (PBLD) has been proven to be a critical regulator of tumor suppression and antiviral innate immunity; however, its role in pyroptosis remains unexplored. Our current investigation shows that PBLD promotes pyroptosis in bovine parainfluenza virus 3 (BPIV3)- or herpes simplex virus type 1 (HSV-1)-triggered HeLa cells, along with BPIV3- or bovine ephemeral fever virus (BEFV)-infected BHK-21 cells, as manifested by increased hallmark features of pyroptosis, including cell swelling, plasma membrane disintegration, elevated lactate dehydrogenase (LDH) release, and reduced cell survival. Further studies reveal that PBLD facilitates virus-induced pyroptosis mediated by GSDME N-terminal cleavage but independent of GSDMD cleavage. Using caspase-specific inhibitors and knockout cell lines, we identify Caspase-3, but not Caspase-8, as essential for virus-induced GSDME-dependent pyroptosis. Mechanistically, PBLD enhances Caspase-3 activation by upregulating PUMA mRNA levels via the NF-κB signaling pathway. Furthermore, silencing of NF-κB abolishes PBLD-induced PUMA upregulation and Caspase-3 and GSDME cleavage. In summary, these findings reveal that PBLD potentiates virus-triggered pyroptosis through the NF-κB/PUMA/Caspase-3/GSDME signaling pathway. This investigation provides unprecedented understanding of the molecular mechanisms by which PBLD regulates cell death and highlights its promise as a pharmacological target for viral infections and inflammatory diseases.