Reduced cGMP signaling activates NF-κB in hypertrophied hearts of mice lacking natriuretic peptide receptor-A

Mice lacking natriuretic peptide receptor-A (NPRA) develop progressive cardiac hypertrophy and congestive heart failure. However, the mechanisms responsible for cardiac hypertrophic growth in the absence of NPRA signaling are not yet known. We sought to determine the activation of nuclear factor-κB (NF-κB) in Npr1 (coding for NPRA) gene-knockout (Npr1−/−) mice exhibiting cardiac hypertrophy and fibrosis. NF-κB binding activity was 4-fold greater in the nuclear extract of Npr1−/− mutant mice hearts as compared with wild-type (Npr1+/+) mice hearts. In parallel, inhibitory κB kinase-β activity and IκB-α protein phosphorylation were also increased 3- and 4-fold, respectively, in hypertrophied hearts of mutant mice. cGMP levels were significantly reduced 5-fold in plasma and 10-fold in ventricular tissues of mutant mice hearts relative to wild-type controls. The present findings provide direct evidence that ablation of NPRA/cGMP signaling activates NF-κB binding activity associated with hypertrophic growth of mutant mice hearts.