STAT5 activity downstream of IgE and IgG receptors in mast cells (177.8)

Abstract

Abstract Removal of STAT5 impairs mast cell development, survival, and IgE-mediated cytokine production, justifying a need to closely investigate its activity downstream of Fc receptors. We found that STAT5 tyrosine phosphorylation occurs shortly after FcϵRI crosslinking in a Fyn-dependent manner, while the suppression of Lyn, and other negative regulators of IgE signaling, appears to enhance STAT5 activation. Tyrosine phosphorylation of STAT5 also occured during IgG-mediated activity, suggesting some overlap in the signaling proximal to different Fc receptors in mast cells. Additionally, IgE- and IgG-mediated signaling elicited serine phosphorylation of both STAT5A and STAT5B, possibly in a divergent manner. Inhibition of Syk ablated IgE-mediated pS-STAT5, but affected to a lesser extent, if at all, pS-STAT5B and IgG-mediated total pS-STAT5. Furthermore, inhibition of JNK reduced pS-STAT5 during FcγR crosslinking. Collectively, these data highlight similarities and differences from variable receptor inputs as well as the different STAT5 proteins, supporting their essential roles in mast cell biology.