Glycogen Synthase Kinase-3β Facilitates IFN-γ-Induced STAT1 Activation by Regulating Src Homology-2 Domain-Containing Phosphatase 2

Abstract

Glycogen synthase kinase-3β (GSK-3β)-modulated IFN-γ-induced inflammation has been reported; however, the mechanism that activates GSK-3β and 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.

Helicobacter pylori Infection Activates Src Homology-2 Domain–Containing Phosphatase 2 To Suppress IFN-γ Signaling

“…Studies in our laboratory have shown that glycogen synthase kinase (GSK)-3b has a suppressive role on SHP2 phosphorylation, while pharmacologically inhibiting GSK-3b facilitated SHP2 activation followed by SHP2-mediated IFN-g resistance (36,65). Notably, in H. pylori infection, PI3K/Akt signaling may inactivate GSK-3b followed by b-catenin stabilization to promote gastric tumorigenesis (66,67).…”

“…To detect the expression of E-cadherin, IFNGR1, IFNGR2, CagA, phosphorylated SHP2 (Tyr 542 ), and SHP2, we fixed, stained, and analyzed the cells as described previously (36). Cells were stained with primary Abs and then incubated with a mixture of Alexa Fluor 488-or 594-conjugated goat anti-mouse or rabbit IgG.…”

“…shRNA clones were obtained from the National RNAi Core Facility (Institute of Molecular Biology/Genomic Research Center, Academia Sinica, Taipei, Taiwan). Lentiviruses were prepared and cells were infected according to previously described protocols (36). Briefly, MKN45 cells were transduced with a lentivirus at an appropriate multiplicity of infection (MOI) in complete growth medium supplemented with polybrene (Sigma-Aldrich).…”

Glycogen Synthase Kinase-3 Facilitates Con A-Induced IFN-γ–Mediated Immune Hepatic Injury

“…shRNA clones were obtained from the National RNAi Core Facility, Institute of Molecular Biology/Genomic Research Center, Academia Sinica (Taipei, Taiwan). Lentiviruses were prepared, and cells were infected, according to previously described protocols (55).…”

“…The proapoptotic and proinflammatory properties of GSK-3 have also been demonstrated in various animal models of inflammation, including experimental lung injury, shock, spinal cord trauma, arthritis, ischemia/reperfusion injury, infection, asthma, colitis, renal failure, and hepatotoxicity (36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50). GSK-3 is currently a known regulator of IFN-g signaling and is involved in IFN-g-induced inflammatory activation (51)(52)(53)(54)(55)(56)(57)(58)(59). Previous studies performed by ourselves and others identified a proinflammatory role for GSK-3 and found that inhibiting GSK-3 provides cellular protection against IFN-g (54-56)-, TNF-a (60)-, and LPS-induced inflammation in vitro (61)(62)(63) and multiple organ failure in vivo (46,47,49,63).…”