The Natriuretic Peptide Receptors NPR-A and NPR-B Are Differentially Regulation by Extracellular Matrix Proteins

Abstract

BackgroundCardiac fibroblasts (CFs) regulate myocardial remodeling by proliferating, differentiating, and secreting extra-cellular matrix proteins (ECMs). Natriuretic peptides (NPs) are anti-fibrotic, inhibiting collagen production, augmenting matrix metalloproteinases, and suppressing CF proliferation. Recently, we demonstrated that the ECM proteins fibronectin (FN) and Collagen IV (Col IV) augmented production of BNP's second messenger cGMP in CFs, supporting crosstalk between these ECM components and BNP involving its particulate guanylyl cyclase receptor, NPR-A. The goal of this investigation was to assess whether CNP and CNP-like peptides, which signal through the NPR-B receptor, are also affected by the ECM.MethodsHuman CFs were cultured as previously described on ECM coated or non-coated plates. Cyclic GMP assays were done as previously reported.ResultsAs previously observed, BNP in vitro induced a dose dependent increase in cGMP which was augmented by FN and Col IV (p<0.05) that was abrogated by NPR-A antibody blockade. In contrast, activation of cGMP by two known active forms of CNP, CNP-22 and CNP-53 which bind to NPR-B, were not affected by ECM presence. Interestingly, the designer peptide CD-NP, known to signal through both NPR-A and NPR-B demonstrated an increase in cGMP with FN and Col IV similar to that observed with BNP.ConclusionOur data suggests that NPR-A activation is augmented by ECM while NPR-B activation is not which may be important in understanding the physiological role of these cGMP receptors in the regulation of myocardial remodeling and guiding natriuretic peptide based therapeutics in its inhibition. Interestingly, the CNP-like chimeric in CF's demonstrates properties of BNP supporting its unique role as an anti-fibrotic therapeutic. BackgroundCardiac fibroblasts (CFs) regulate myocardial remodeling by proliferating, differentiating, and secreting extra-cellular matrix proteins (ECMs). Natriuretic peptides (NPs) are anti-fibrotic, inhibiting collagen production, augmenting matrix metalloproteinases, and suppressing CF proliferation. Recently, we demonstrated that the ECM proteins fibronectin (FN) and Collagen IV (Col IV) augmented production of BNP's second messenger cGMP in CFs, supporting crosstalk between these ECM components and BNP involving its particulate guanylyl cyclase receptor, NPR-A. The goal of this investigation was to assess whether CNP and CNP-like peptides, which signal through the NPR-B receptor, are also affected by the ECM. Cardiac fibroblasts (CFs) regulate myocardial remodeling by proliferating, differentiating, and secreting extra-cellular matrix proteins (ECMs). Natriuretic peptides (NPs) are anti-fibrotic, inhibiting collagen production, augmenting matrix metalloproteinases, and suppressing CF proliferation. Recently, we demonstrated that the ECM proteins fibronectin (FN) and Collagen IV (Col IV) augmented production of BNP's second messenger cGMP in CFs, supporting crosstalk between these ECM components and BNP involving its particulate guanylyl cyclase receptor, NPR-A. The goal of this investigation was to assess whether CNP and CNP-like peptides, which signal through the NPR-B receptor, are also affected by the ECM. MethodsHuman CFs were cultured as previously described on ECM coated or non-coated plates. Cyclic GMP assays were done as previously reported. Human CFs were cultured as previously described on ECM coated or non-coated plates. Cyclic GMP assays were done as previously reported. ResultsAs previously observed, BNP in vitro induced a dose dependent increase in cGMP which was augmented by FN and Col IV (p<0.05) that was abrogated by NPR-A antibody blockade. In contrast, activation of cGMP by two known active forms of CNP, CNP-22 and CNP-53 which bind to NPR-B, were not affected by ECM presence. Interestingly, the designer peptide CD-NP, known to signal through both NPR-A and NPR-B demonstrated an increase in cGMP with FN and Col IV similar to that observed with BNP. As previously observed, BNP in vitro induced a dose dependent increase in cGMP which was augmented by FN and Col IV (p<0.05) that was abrogated by NPR-A antibody blockade. In contrast, activation of cGMP by two known active forms of CNP, CNP-22 and CNP-53 which bind to NPR-B, were not affected by ECM presence. Interestingly, the designer peptide CD-NP, known to signal through both NPR-A and NPR-B demonstrated an increase in cGMP with FN and Col IV similar to that observed with BNP. ConclusionOur data suggests that NPR-A activation is augmented by ECM while NPR-B activation is not which may be important in understanding the physiological role of these cGMP receptors in the regulation of myocardial remodeling and guiding natriuretic peptide based therapeutics in its inhibition. Interestingly, the CNP-like chimeric in CF's demonstrates properties of BNP supporting its unique role as an anti-fibrotic therapeutic. Our data suggests that NPR-A activation is augmented by ECM while NPR-B activation is not which may be important in understanding the physiological role of these cGMP receptors in the regulation of myocardial remodeling and guiding natriuretic peptide based therapeutics in its inhibition. Interestingly, the CNP-like chimeric in CF's demonstrates properties of BNP supporting its unique role as an anti-fibrotic therapeutic.