Glycogen synthase kinase-3β facilitates IFN-γ-induced STAT1 activation by regulating Src homology-2 domain-containing phosphatase 2

Glycogen synthase kinase-3β(GSK-3β)-modulated IFN-γ-induced inflammation has been reported; however, the mechanism that activates GSK-3βand the effects of activation remain unclear. Inhibiting GSK-3β decreased IFN-γ-induced inflammation. IFN-γ treatment rapidly activated GSK-3β via neutral sphingomyelinase- and okadaic acid-sensitive phosphatase-regulated dephosphorylation at Ser⁹, and proline-rich tyrosine kinase 2 (Pyk2)-regulated phosphorylation at Tyr²¹⁶. Pyk2 was activated through phosphatidylcholine-specific phospholipase C (PC-PLC)-, protein kinase C (PKC)-, and Src-regulated pathways. The activation of PC-PLC, Pyk2, and GSK-3β was potentially regulated by IFN-γ receptor 2-associated Jak2, but it was independent of IFN-γ receptor 1. Furthermore, Jak2/PC-PLC/PKC/cytosolic phospholipase A₂ positively regulated neutral sphingomyelinase. Inhibiting GSK-3β activated Src homology-2 domain-containing phosphatase 2 (SHP2), thereby preventing STAT1 activation in the late stage of IFN-γ stimulation. All these results showed that activated GSK-3β synergistically affected IFN-γ-induced STAT1 activation by inhibiting SHP2.