Tyrosine phosphatase inhibition induces an ASC-dependent pyroptosis

• Published in: Biochemical and biophysical research communications 2012-08, Vol.425 (2), p.384-389
• Main Authors: Ghonime, Mohammed G., Shamaa, Obada R., Eldomany, Ramadan A., Gavrilin, Mikhail A., Wewers, Mark D.
• Format: Article
• Language: English
• Subjects: ASC; CARD Signaling Adaptor Proteins; Caspase 1 - chemistry; Caspase 1 - metabolism; Caspase Inhibitors - pharmacology; Caspase-1; Cell Death - drug effects; Cell Death - physiology; Cell Line; Cytoskeletal Proteins - chemistry; Humans; IL-1β; Inflammasome; Interleukin-1beta - metabolism; Lipopolysaccharides; Oligopeptides - pharmacology; Phosphatases; Protein Structure, Tertiary; Protein Tyrosine Phosphatases - antagonists & inhibitors; Pyroptosis; Vanadates - pharmacology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2012.07.102

► Pyroptosis is induced through the inhibition of a tyrosine phosphatase by sodium orthovanadate. ► Phosphatase inhibition induces ASC speck formation and secretion of IL-1β. ► Phosphorylation is important in the activation of caspase-1 and induction of pyroptosis. Pyroptosis is a type of cell death in which danger associated molecular patterns (DAMPs) and pathogen associated molecular patterns (PAMPs) induce mononuclear phagocytes to activate caspase-1 and release mature IL-1β. Because the tyrosine kinase inhibitor AG126 can prevent DAMP/PAMP induced activation of caspase-1, we hypothesized that tipping the tyrosine kinase/phosphatase balance toward phosphorylation would promote caspase-1 activation and cell death. THP-1 derived macrophages were therefore treated with the potent specific tyrosine phosphatase inhibitor, sodium orthovanadate (OVN) and analyzed for caspase-1 activation and cell death. OVN induced generalized increase in phosphorylated proteins, IL-1β release and cell death in a time and dose dependent pattern. This OVN induced pyroptosis correlated with speck formations that contained the apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC). Culturing the cells in the presence of extracellular K+ (known to inhibit ATP dependent pyroptosis), a caspase inhibitor (ZVAD) or down regulating the expression of ASC with stable expression of siASC prevented the OVN induced pyroptosis. These data demonstrate that pyroptotic death is linked to tyrosine phosphatase activity providing novel targets for future pharmacologic interventions.