Ikaros regulates IL-10 expression in CD4+ T cells (38.27)

Abstract

Abstract IL-10 is a regulatory cytokine critical for controlling inflammatory responses. However, little is known about the molecular mechanisms controlling Il10 gene expression, although GATA-3 is known to be involved in Il10 expression by Th2 cells. Here we show that Ikaros, a zinc finger DNA-binding protein, plays an important role in the regulation of IL-10 in T cells. Upon initial stimulation by T cell receptor, cells deficient in Ikaros (Ikaros null) express significantly lower levels of IL-10 compared to wild type T cells. In addition, under Th2 skewing conditions, which induce high levels of IL-10 production by wild type cells, Ikaros null T cells are unable to properly differentiate and produce only low levels of IL-10. The use of a retroviral vector system to express a dominant negative isoform of Ikaros in wild type Th2 cells represses IL-10 production but does not significantly alter the levels of transcription factors Gata3 and Tbet. Further, expression of Ikaros in Ikaros null T cells restores IL-10 expression. We found that Ikaros binds to conserved regulatory regions of the Il10 gene locus in Th2 cells, supporting a direct role for Ikaros in Il10 expression. In addition, we have evidence to suggest a coordinate role for Ikaros and Gata3 in the regulation of Il10. A direct interaction of these proteins is being examined. Thus, we suggest of novel role of Ikaros in regulating Il10 gene expression.