| First Author | Chornoguz O | Year | 2017 |
| Journal | J Immunol | Volume | 198 |
| Issue | 10 | Pages | 3939-3948 |
| PubMed ID | 28424242 | Mgi Jnum | J:247857 |
| Mgi Id | MGI:5926543 | Doi | 10.4049/jimmunol.1601078 |
| Citation | Chornoguz O, et al. (2017) mTORC1 Promotes T-bet Phosphorylation To Regulate Th1 Differentiation. J Immunol 198(10):3939-3948 |
| abstractText | CD4+ T cells lacking the mTORC1 activator Rheb fail to secrete IFN-gamma under Th1 polarizing conditions. We hypothesized that this phenotype is due to defects in regulation of the canonical Th1 transcription factor T-bet at the level of protein phosphorylation downstream of mTORC1. To test this hypothesis, we employed targeted mass-spectrometry proteomic analysis-multiple reaction monitoring mass spectrometry. We used this method to detect and quantify predicted phosphopeptides derived from T-bet. By analyzing activated murine wild-type and Rheb-deficient CD4+ T cells, as well as murine CD4+ T cells activated in the presence of rapamycin, a pharmacologic inhibitor of mTORC1, we were able to identify six T-bet phosphorylation sites. Five of these are novel, and four sites are consistently dephosphorylated in both Rheb-deficient CD4+ T cells and T cells treated with rapamycin, suggesting mTORC1 signaling controls their phosphorylation. Alanine mutagenesis of each of the six phosphorylation sites was tested for the ability to impair IFN-gamma expression. Single phosphorylation site mutants still support induction of IFN-gamma expression; however, simultaneous mutation of three of the mTORC1-dependent sites results in significantly reduced IFN-gamma expression. The reduced activity of the triple mutant T-bet is associated with its failure to recruit chromatin remodeling complexes to the Ifng gene promoter. These results establish a novel mechanism by which mTORC1 regulates Th1 differentiation, through control of T-bet phosphorylation. |
