The Ets transcription factor PU.1 is a master regulator for the development of multiple lineages during hematopoiesis. The expression of PU.1 is regulated during early T lineage development in the thymus.
Spi-1 (PU.1) 5' UTR regulatory element. Image source: Wikipedia, public domain.
PU.1 modulates the levels of TCR expression in CD4(+) T cells by regulating the DNA-binding activity of GATA-3.
GATA-3-dependent regulation of TCR expression is also observed in Th1 and Th2 cells.
Increased GATA-3 function in the absence of the antagonizing activity of PU.1 leads to:
- increased TCR expression
- reduced activation threshold
- increased homogeneity in Th2 populations
PU.1 regulates TCR expression by modulating GATA-3 activity. Chang HC, Han L, Jabeen R, Carotta S, Nutt SL, Kaplan MH. J Immunol. 2009 Oct 15;183(8):4887-94.