Homeobox protein Nkx-2.5
transcription cis-regulatory region binding
NKX2-5 regulates the expression of beta-catenin and GATA4 in ventricular myocytes.
<h4>Background</h4>The molecular pathway that controls cardiogenesis is temporally and spatially regulated by master transcriptional regulators such as NKX2-5, Isl1, MEF2C, GATA4, and beta-catenin. The interplay between these factors and their downstream targets are not completely understood. Here, we studied regulation of beta-catenin and GATA4 by NKX2-5 in human fetal cardiac myocytes.<h4>Methodology/principal findings</h4>Using antisense inhibition we disrupted the expression of NKX2-5 and studied changes in expression of cardiac-associated genes. Down-regulation of NKX2-5 resulted in increased beta-catenin while GATA4 was decreased. We demonstrated that this regulation was conferred by binding of NKX2-5 to specific elements (NKEs) in the promoter region of the beta-catenin and GATA4 genes. Using promoter-luciferase reporter assay combined with mutational analysis of the NKEs we demonstrated that the identified NKX2-5 binding sites were essential for the suppression of beta-catenin, and upregulation of GATA4 by NKX2-5.<h4>Conclusions</h4>This study suggests that NKX2-5 modulates the beta-catenin and GATA4 transcriptional activities in developing human cardiac myocytes.