Abstract 15073: Type B Human Natriuretic Peptide Receptor with a novel gain-of-function mutation provides therapeutic potential in the treatment of pulmonary arterial hypertension
Introduction: Cyclic GMP (cGMP) is a ubiquitous second messenger that plays a central role in diverse physiologic processes. In humans, type B natriuretic peptide receptor (NPR-B) is one of the transmembrane guanylyl cyclases and synthesizes cGMP in response to C-type natriuretic peptide (CNP) binding. The CNP/NPR-B pathway functions in a paracrine manner in both the pulmonary and systemic circulations. The nitric oxide/cGMP pathway has been recognized as an important therapeutic target in PAH and clinically approved drugs are available. However, therapeutic application of the CNP/NPR-B pathway in PAH has not been developed yet.
Methods and Results: Recently, we have identified a novel missense mutation in the NPR-B gene (2647G>A; Val 883 Met) in a family case showing overgrowth and bone anomalies. To test whether this single amino acid substitution can alter NPR-B function, we generated the corresponding mutant receptor cDNA (Mut-NPR-B) as well as the wild type cDNA (WT-NPR-B). Overexpression of the mutated protein in HEK293A cells or human pulmonary artery smooth muscle cells (PASMCs) induced significant increase in cGMP levels compared to WT-NPR-B or GFP control in a ligand-independent manner (GFP, 0.097±0.050 pmol/L; WT-NPR-B, 0.084±0.039 pmol/L; Mut-NPR-B, 18.09±1.39 pmol/L; in PASMCs). Moreover, the addition of CNP in the transfected PASMCs induced a further increase in cGMP levels in a dose-dependent manner. Overexpression of Mut-NPR-B suppressed PASMCs proliferation under hypoxia compared to WT-NPR-B or GFP.
Conclusion: Transfection of mutant NPR-B with a novel gain-of-function mutation induced significant increase in intracellular cGMP levels and inhibited proliferation of human PASMCs. The CNP/NPR-B pathway may be an additional therapeutic target in the treatment of PAH.
- © 2011 by American Heart Association, Inc.