Cardiac hormones atrial and brain natriuretic peptides activate guanylyl cyclase/natriuretic peptide receptor-A (GC-A/ NPRA), which plays a critical role in reduction of blood pressure and blood volume. Currently, the mechanisms responsible for regulating the Npr1 gene (coding for GC-A/NPRA) transcription are not well understood. The present study was conducted to examine the interactive roles of all-trans retinoic acid (ATRA), Ets-1, Sp1, and histone acetylation on the transcriptional regulation and function of the Npr1 gene. Deletion analysis of the Npr1 promoter and luciferase assays showed that ATRA enhanced a 16-fold Npr1 promoter activity and greatly stimulated guanylyl cyclase (GC) activity of the receptor protein in both atrial natriuretic peptide (ANP)-dependent and -independent manner. As confirmed by gel shift and chromatin immunoprecipitation assays, ATRA enhanced the binding of both Ets-1 and Sp1 to the Npr1 promoter. The retinoic acid receptor ␣ (RAR␣) was recruited by Ets-1 and Sp1 to form a transcriptional activator complex with their binding sites in the Npr1 promoter. Interestingly, ATRA also increased the acetylation of histones H3 and H4 and enhanced their recruitment to Ets-1 and Sp1 binding sites within the Npr1 promoter. Collectively, the present results demonstrate that ATRA regulates Npr1 gene transcription and GC activity of the receptor by involving the interactive actions of Ets-1, Sp1, and histone acetylation.
Atrial natriuretic peptide (ANP)2 is a circulatory hormone, which plays a pivotal role in the regulation of sodium excretion, fluid volume, steroidogenesis, and cell proliferation, important factors in the control of blood pressure and blood volume (1-4). One of the principal loci involved in the regulatory actions of ANP is the guanylyl cyclase/natriuretic peptide receptor-A (GC-A/NPRA), which produces the intracellular second messenger cGMP, thus plays a central role in the pathophysiology of hypertension and cardiovascular disorders (4 -7). The signaling of ANP/cGMP through its downstream effector proteins, including cGMP-dependent protein kinases, phosphodiesterases, and cyclic nucleotide-gated ion channels, mediates the cellular effects of NPRA (4, 8). Gene-targeting and expression studies of Npr1 (coding for GC-A/NPRA) have identified the hallmark significance of this receptor in protecting against renal and cardiac pathophysiological conditions such as inhibiting the cardiac hypertrophic growth and fibrosis, extracellular matrix remodeling, and cell proliferation (9 -13). Earlier studies have demonstrated a significant association of Npr1 gene variants with hypertensive family history, left ventricular mass index, and left ventricular septal wall thickness in human essential hypertension (14, 15). It has also been shown that a longer thymine adenine repeat unit in spontaneously hypertensive rats regulates the transcription of the Npr1 gene, thus affecting diastolic blood pressure (16). Little is known about transcriptional regulation of the Npr1 gene, but the activity an...