Transcriptional Regulation of Gata3 in T Helper Cells by the Integrated Activities of Transcription Factors Downstream of the Interleukin-4 Receptor and T Cell Receptor

Eyal J Scheinman,Orly Avni

doi:10.1074/jbc.m807302200

Abstract

GATA3 is a critical transcription factor for many developmental processes. During T helper (Th) cell differentiation, GATA3 induces the Th2 and suppresses the Th1 pathway. Stimulation of the T cell receptor (TCR) of naive Th cells in the presence of interleukin 4 (IL-4) induces robust expression of GATA3; however, it is unclear where these signals integrate. Gata3 encodes two transcripts that differ in their alternative, untranslated first exons. We show here the involvement of the TCR-inducible transcription factor NFAT1 in the transcriptional regulation of both Gata3 transcripts following TCR stimulation of naive and differentiated Th2 cells. We also show that IL-4 is important for the initiation and establishment of Gata3 transcription in developing Th2 cells, especially from the distal promoter. The early function of IL-4 can be STAT6 dependent or independent. However, the establishment of the activity of the distal promoter is totally dependent on STAT6, whereas it is likely that the proximal promoter has additional activation mechanisms that are STAT6 independent. Our findings suggest that different combinations of transcription factors downstream of the IL-4 receptor (IL-4R) and TCR finely modulate Gata3 gene expression from its two promoters for optimal Th2 differentiation.

Highlights

We found by Chromatin Immunoprecipitation (ChIP) analysis that GATA3 was bound to both promoters, coding Sequences (CNSs) I, and exon 1b, in resting differentiated Th2 cells (Fig. 5A), that activity can underlie the ability of GATA3 to autoregulate its own expression [4, 36], and to maintain it even in unstimulated cells (Fig. 1C)
Tight regulation of GATA3 expression is critical for many developmental processes, and its aberrant expression is associated with diseases in humans and mice [14, 16, 25, 27, 28, 30]
Our results strongly suggest the involvement of NFAT1 in the transcriptional regulation of both Gata3 promoters during early T helper (Th) cell differentiation and after the stimulation of the differentiated cells

Summary

Introduction

To quantify the ratio between the expression levels of the Gata3 transcripts during Th cell development and in the differentiated Th cells, we performed an exon-specific quantitative PCR analysis. To test the importance of IL-4 for the expression of Gata3 transcripts early in differentiation, naive Th cells were stimulated for 12 and 18 h in the presence (Th2) or absence (neutral; N) of exogenous IL-4 (Fig. 4C, upper panels).

Results

Conclusion