c-Abl-Mediated Tyrosine Phosphorylation of the T-bet DNA-Binding Domain Regulates CD4⁺ T-Cell Differentiation and Allergic Lung Inflammation

Abstract

The tyrosine kinase c-Abl is required for full activation of T cells, while its role in T-cell differentiation has not been characterized. We report that c-Abl deficiency skews CD4 ؉ T cells to type 2 helper T cell (Th2) differentiation, and c-Abl ؊/؊ mice are more susceptible to allergic lung inflammation. c-Abl interacts with and phosphorylates T-bet, a Th1 lineage transcription factor. c-Abl-mediated phosphorylation enhances the transcriptional activation of T-bet. Interestingly, three tyrosine residues within the T-bet DNA-binding domain are the predominant sites of phosphorylation by c-Abl. Mutation of these tyrosine residues inhibits the promoter DNA-binding activity of T-bet. c-Abl regulates Th cell differentiation in a T-bet-dependent manner because genetic deletion of T-bet in CD4 ؉ T cells abolishes c-Abl-deficiency-mediated enhancement of Th2 differentiation. Reintroduction of T-bet-null CD4؉ T cells with wild-type T-bet, but not its tyrosine mutant, rescues gamma interferon (IFN-␥) production and inhibits Th2 cytokine production. Therefore, c-Abl catalyzes tyrosine phosphorylation of the DNA-binding domain of T-bet to regulate CD4 ؉ T cell differentiation.

mTORC1 Promotes T-bet Phosphorylation To Regulate Th1 Differentiation

“…Published data (13, 14, 16) suggested that within T-bet, S52, Y76 and S224 phosphorylation sites could be important for T-bet’s ability to induce IFNγ expression by influencing either its ability to bind DNA and/or interact with chromatin remodeling complexes. A distinct phosphorylation site, S508, has been previously demonstrated to be important for suppression of IL-2 production by T-bet (15).…”

“…Previously 3 other T-bet phosphorylation sites within the T-box region (Y219/Y265/Y304) have been demonstrated to be crucial for T-bet’s ability to bind DNA proximal to its target genes (16). T-bet promotes the expression of its target genes via two mechanisms.…”

“…T-bet phosphorylation at residues T302 and S508 are involved in suppression of IL-2 production (14, 15); Y219/Y265/Y304 triple phosphorylation by c-Abl tyrosine kinase regulates T-bet’s ability to bind to DNA of its target genes and promote gene expression (16). Y304 is crucial for T-bet’s interaction with RUNX1 transcription factor and inhibition of Th17 differentiation (17).…”

Histone Deacetylase Sirtuin 1 Deacetylates IRF1 Protein and Programs Dendritic Cells to Control Th17 Protein Differentiation during Autoimmune Inflammation

“…Luciferase Assay-Experiments were performed as described (20). Briefly, HEK293 cells in 12-well plates were transfected with pRL-TK (Promega, Madison, WI), and each of Sirt1-luc plasmids, along with EGR2, EGR3, or FoxO3a expression plasmids or both as indicated.…”

Transcriptional Regulatory Networks for CD4 T Cell Differentiation

“…Indeed, Runx3 is able to interact with Gata3 (Yagi et al 2010), as does phosphorylated Tbet, and this interaction inhibits Th2 differentiation by blocking the binding of Gata3 to target genes (Hwang et al 2005b). Increased levels of phosphorylated Tbet correlated with increased IFNγ expression while inhibition of Tbet phosphorylation resulted in increased Th2 differentiation (Chen et al 2011a). Tbet also binds directly to the Gata3 gene and increases restrictive histone modifications to repress Gata3 expression (Zhu et al 2012).…”