NF90 and NF45 Regulate Interleukin‐13 (IL13) Gene Transcription in Human T Cells

Abstract

The Th2 cytokine IL13 is a critical effector of allergic inflammation. We previously showed human IL13 gene expression is paralleled by chromatin remodeling, leading to the formation of multiple DNase I hypersensitive (HS) sites throughout the locus. The distal IL13 promoter harbors two HS sites, HS4 and HS5, detected in both naïve and polarized CD4+ T helper cells. We now show HS4, which is located ~1.5 kb upstream of the IL13 ATG, acts as a cis‐regulatory element that enhances transcription driven by the IL13 promoter in transiently transfected, activated Jurkat T cells. The enhancing activity mapped to the 3’half of HS4 (HS4‐3’), a region which binds Nuclear Factor‐90 (NF90) and NF45 as demonstrated by DNA‐affinity chromatography and tandem mass spectrometry. The NF90/45 binding motif in HS4‐3’ was further mapped and dissected by gel shift analysis. Chromatin immunoprecipitation confirmed recruitment of NF90 and NF45 to the HS4‐containing region in the endogenous IL13 locus upon T cell stimulation. Moreover, stable overexpression of NF90 and NF45 increased HS4‐mediated enhancement of IL13 transcription by 3‐fold and 4‐fold, respectively. Collectively, our results identify NF90 and NF45 as important regulators of human IL13 transcription in response to T cell activation.