C/EBP transcription factors are involved in the regulation of the intestinal epithelial cell response to inflammatory stimuli. GATA transcription factors modulate C/EBP-dependent transcriptional activation in various cell types. We thus determined whether GATA-4 whose expression is restricted to epithelial cells, modulate C/EBP transcriptional activity and C/EBP-dependent acute phase protein expression in intestinal epithelial cells. Interaction between C/EBPdelta and GATA-4 required both C/EBPdelta leucine zipper and basic DNA-binding domains, and the GATA-4 C-terminal region. C/EBP isoforms and GATA-4 synergistically activated the alpha-acid glycoprotein gene while GATA-4 repressed thiostatin and haptoglobin C/EBP-dependent transactivation. In GATA-4 expressing intestinal epithelial cells, GATA-4 led to decreased C/EBPbeta and C/EBPdelta protein levels, and decreased thiostatin expression in response to IL-1beta and dexamethasone. This correlated with decreased C/EBPdelta recruitment to the thiostatin promoter, as assessed by chromatin immunoprecipitation assays. In contrast, increased AGP expression in response to dexamethasone correlated with increased basal histone H4 acetylation. Thus, GATA-4 may be involved in the establishment of specific intestinal epithelial cell C/EBP-dependent and C/EBP-independent transcriptional responses.