Angiotensin II‐mediated Repression of Guanylyl Cyclase/Natriuretic Peptide Receptor‐A Gene Expression Involving CREB, HSF4a, and HDAC1/2 in Mesangial Cells

Abstract

Atrial natriuretic peptide (ANP) is an endogenous cardiac hormone that binds to guanylyl‐cyclase/natriuretic peptide receptor‐A (GC‐A/NPRA) and regulates sodium excretion, water balance, and steroidogenesis; all directed toward the reduction of blood pressure and blood volume. The present study was aimed at understanding the mechanisms involved in angiotensin II (Ang II)‐mediated repression of Npr1 (coding for GC‐A/NPRA) gene transcription. The mouse mesangial cells (MMCs) were cultured in Dulbecco's modified Eagle's medium (DMEM) containing 10% fetal bovine serum and ITS (insulin, transferrin, and sodium selenite) and treated with Ang II for 24 h. The luciferase assay of the Npr1 promoter deletion constructs showed that the region approximately –1182/–916 bp upstream of the transcription start site contains the cis‐elements involved in ANG II‐mediated transcriptional repression of Npr1. Real‐time quantitative PCR and Western blot analyses revealed that Npr1 mRNA expression and NPRA protein levels were reduced by 60 – 65% in Ang II‐treated MMCs. Treatment with Ang II also significantly decreased ANP‐stimulated intracellular accumulation of cGMP as compared with ANP‐stimulated cells. Gel mobility shift assays confirmed that Ang II enhanced the binding of transcription factors cAMP‐response element‐binding protein (CREB) and heat shock factor 4a (HSF4a) to the Npr1 promoter. Increasing concentrations of Ang II also decreased the acetylation levels of histone H3 at lysine 9 and 14 and histone H4 at lysine 8. In contrast, there was significant increase in protein expression of prohypertrophic Class 1 histone deacetylase (HDAC) 1 and 2. Treatment of MMCs with Ang II increased the activity of HDAC in a dose‐dependent manner. The present findings provide a novel regulatory mechanism of Ang II‐mediated repression of Npr1 transcription and expression, which plays an important role in the control of hypertension and cardiovascular homeostasis.Support or Funding InformationThis work was supported by NIH grants (HL057531 and HL062147).