RNA sequencing of WT and MSC KO iTreg cells

Although the master transcription factors (TFs) are the key to the development of specific T cell subsets, whether additional transcriptional regulators are induced by the same stimuli that dominantly repress development of other T cell lineages has not been fully elucidated. Using Transforming growth factor-b (TGF-b) induced regulatory T cell (iTreg) system, we identify the TF Musculin (MSC) as critical for iTreg development by repression of TH2 transcriptional program. Loss of MSC reduces Foxp3 expression and induces TH2 differentiation even under TGF-b induced iTreg differentiation conditions. MSC mediates this effect by interrupting binding of GATA3 to TH2 locus and reducing intrachromosomal interactions within the Th2 locus. MSC-deficient iTregs are not able to suppress TH2 responses and the Msc–/– mice spontaneously develop gut and lung inflammation with age. Our data indicate that MSC enforces Foxp3 expression and promotes unidirectional induction of iTregs by repressing development of the TH2 developmental program. mRNA profiles of in vitro differentiated iTreg cells from WT and MSC KO mice by deep sequencing.