T-box transcription factor TBX21 (TBX21)

Lineage-defining transcription factor that initiates Th1 lineage development from naive Th precursor cells both by activating Th1 genetic programs and by repressing the opposing Th2 and Th17 genetic programs (PubMed:10761931). Activates transcription of a set of genes important for Th1 cell function, such as those encoding IFN-gamma and the chemokine receptor CXCR3.

Activates IFNG and CXCR3 genes in part by recruiting chromatin remodeling complexes such as KDM6B, a SMARCA4- comprising SWI/SNF-complex, and an H3K4me2-methyltransferase complicated for their promoters and all these complexes function to establish a more permissive chromatin state conducive with transcriptional activation (By similarity). Can trigger Th1 genes also through recruitment of Mediator complex and P-TEFb (composed of CDK9 and CCNT1/cyclin-T1) in the form of the super elongation complex (SEC) to super-enhancers and associated genes in activated Th1 cells (PubMed:27292648).