Regulation of the SMyHC iii promoter by the nuclear receptors AR, GR and Coup-TFII: a solo or joint work?

Abstract

Nuclear Receptors (NRs) correspond to a superfamily of ligand modulated transcription factors that act in the regulation of specific genes. The orphan receptor, Coup-TFII (Chiken ovalbumin upstream promoter transcription factor) has been suggested as one of the key factors involved in cardiac development, controlling slow myosin heavy chain (SMyHC III) gene. The promoter involved in the atrial differentiation and activates the SMyHC III gene, owns a "complex 33-base pair nuclear receptor response element" (CNRRE) sequence, which containing probable binding sites for NRs, such as Coup -TF II. Transient transfection studies performed by our research group revealed Coup-TFII activation on the SmyHC III promoter, which specifically binds to CNRRE. In addition, previous studies have shown differences in this promoter activation under different combinations of androgens receptor (AR) and glucocorticoids receptor (GR) with Coup-TFII, suggesting a possible cooperation between Coup-TFII, GR and AR. Therefore, this study aims to evaluate, in vitro, protein-protein and protein-DNA interactions involving the AR, GRs and COUP-TFII and the possible relationship between their roles in the atrial development via SMyHC III regulation. The determination of protein-protein and DNA-protein affinities will be performed using fluorescence anisotropy and microscale thermophoresis. Thus, the obtained results through this present work may contribute to the elucidation of regulatory pathways, which act directly or indirectly in the biological process of atrial cardiac differentiation. (AU)