Description
The transcription factor Foxp3 is indispensible for the differentiation and function of regulatory T cells (Treg cells). To gain insights into the molecular mechanisms of Foxp3 mediated gene expression we purified Foxp3 complexes and explored their composition. Biochemical and mass-spectrometric analyses revealed that Foxp3 forms multi-protein complexes of 400-800 kDa or larger and identified 361 associated proteins ~30% of which are transcription-related. Foxp3 directly regulates expression of a large proportion of the genes encoding its co-factors. Reciprocally, some transcription factor partners of Foxp3 facilitate its expression. Functional analysis of Foxp3 cooperation with one such partner, Gata3, provided further evidence for a network of transcriptional regulation afforded by Foxp3 and its associates to control distinct aspects of Treg cell biology.