All-trans retinoic acid and sodium butyrate enhance natriuretic peptide receptor a gene transcription: role of histone modification.

The objective of the present study was to delineate the mechanisms of GC-A/natriuretic peptide receptor-A (GC-A/NPRA) gene (Npr1) expression in vivo. We used all-trans retinoic acid (ATRA) and histone deacetylase (HDAC) inhibitor, sodium butyrate (NaBu) to examine the expression and function of Npr1 using gene-disrupted heterozygous (1-copy; +/-), wild-type (2-copy; +/+), and gene-duplicated heterozygous (3-copy; ++/+) mice. Npr1(+/-) mice exhibited increased renal HDAC and reduced histone acetyltransferase (HAT) activity; on the contrary, Npr1(++/+) mice showed decreased HDAC and enhanced HAT activity compared with Npr1(+)(/+) mice. ATRA and NaBu promoted global acetylation of histones H3-K9/14 and H4-K12, reduced methylation of H3-K9 and H3-K27, and enriched accumulation of active chromatin marks at the Npr1 promoter. A combination of ATRA-NaBu promoted recruitment of activator-complex containing E26 transformation-specific 1, retinoic acid receptor α, and HATs (p300 and p300/cAMP response element-binding protein-binding protein-associated factor) at the Npr1 promoter, and significantly increased renal NPRA expression, GC activity, and cGMP levels. Untreated 1-copy mice showed significantly increased systolic blood pressure and renal expression of α-smooth muscle actin (α-SMA) and proliferating cell nuclear antigen (PCNA) compared with 2- and 3-copy mice. Treatment with ATRA and NaBu synergistically attenuated the expression of α-SMA and PCNA and reduced systolic blood pressure in Npr1(+/-) mice. Our findings demonstrate that epigenetic upregulation of Npr1 gene transcription by ATRA and NaBu leads to attenuation of renal fibrotic markers and systolic blood pressure in mice with reduced Npr1 gene copy number, which will have important implications in prevention and treatment of hypertension-related renal pathophysiological conditions.