Human TAF(II)130 is a coactivator for NFATp

NRATp is one member of a family of transcriptional activators that regulate the expression of cytokine genes. To study mechanisms of NFATp transcripti onal activation, tve established a reconstituted transcription system consi sting of human components that is responsive to activation by full-length N FATp. The TATA-associated factor (TAF(II)) subunits of the TFIID temples we re required for NFATg-mediated activation in this transcription system, sin ce TATA-binding protein (TBP) alone was insufficient in supporting activate d transcription. In vitro interaction assays revealed that human TAF(II)130 (hTAF(II)130) and its Drosophila melanogaster homolog dTAF(II)110 bound sp ecifically and reproducibly to immobilized NFATp. Sequences contained in th e C terminal domain of NFATp (amino acids 688 to 921) were necessary and su fficient for hTAF(II)130 binding. A partial TFIID complex assembled from re combinant hTBP, hTAF(II)250, and hTAF(II)130 supported NFATp-activated tran scription, demonstrating the ability of hTAF(II)130 to serve as a coactivat or for NFATp in vitro. Overexpression of hTAF(II)130 in Cos-1 cells inhibit ed NFATp activation of a luciferase reporter. These studies demonstrate tha t hTAF(II)130 is a coactivator for NFATp and represent the first biochemica l characterization of the mechanism of transcriptional activation by the NF AT family activators.