Upregulation of human with-no-lysine kinase-4 gene expression by GATA-1 acetylation

Abstract With-no-lysine kinase-4 (WNK4), a member of the serine–threonine protein kinase family, acts as a multifunctional regulator of diverse ion transporters. Therefore, it is interesting to investigate the mechanisms that control its expression. We have previously demonstrated that glucocorticoid downregulates human WNK4 (h WNK4 ) expression through the negative glucocorticoid responsive element. Here, using real-time PCR and Western blot assays, we show that trichostatin A (TSA), a histone deacetylase inhibitor, upregulated h WNK4 mRNA and protein expression in human embryo kidney 293 cells. Analysis of the transcriptional activity of a series of the truncated h WNK4 promoters by luciferase assay indicated that the region −484 to −337 of the h WNK4 promoter was sensitive to TSA, and a GATA-1 binding motif was identified at position −426 using TRANSFAC-TESS program. Moreover, using electrophoresis mobility shift assay and chromatin immunoprecipitation assay, the GATA-1 binding affinity to the h WNK4 promoter was shown to increase with TSA under in vitro and in vivo conditions. Immunoprecipitation and Western blot analyses showed that the levels of acetylated GATA-1 were increased with TSA, in agreement with changes in its DNA-binding affinity. These findings indicate that TSA induces h WNK4 expression, at least in part, by increasing GATA-1 acetylation, and thereby its binding to the GATA-1 responsive element, within the h WNK4 promoter.