The natriuretic peptide/guanylyl cyclase–A system functions as a stress-responsive regulator of angiogenesis in mice
Michaela Kuhn, Katharina Völker, Kristine Schwarz, Javier Carbajo-Lozoya, Ulrich Flögel, Christoph Jacoby, Jörg Stypmann, Martin van Eickels, Stepan Gambaryan, Michael Hartmann, Matthias Werner, Thomas Wieland, Jürgen Schrader, Hideo A. Baba
Michaela Kuhn, Katharina Völker, Kristine Schwarz, Javier Carbajo-Lozoya, Ulrich Flögel, Christoph Jacoby, Jörg Stypmann, Martin van Eickels, Stepan Gambaryan, Michael Hartmann, Matthias Werner, Thomas Wieland, Jürgen Schrader, Hideo A. Baba
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Research Article Vascular biology

The natriuretic peptide/guanylyl cyclase–A system functions as a stress-responsive regulator of angiogenesis in mice

Abstract

Cardiac atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) modulate blood pressure and volume by activation of the receptor guanylyl cyclase–A (GC-A) and subsequent intracellular cGMP formation. Here we report what we believe to be a novel function of these peptides as paracrine regulators of vascular regeneration. In mice with systemic deletion of the GC-A gene, vascular regeneration in response to critical hind limb ischemia was severely impaired. Similar attenuation of ischemic angiogenesis was observed in mice with conditional, endothelial cell–restricted GC-A deletion (here termed EC GC-A KO mice). In contrast, smooth muscle cell–restricted GC-A ablation did not affect ischemic neovascularization. Immunohistochemistry and RT-PCR revealed BNP expression in activated satellite cells within the ischemic muscle, suggesting that local BNP elicits protective endothelial effects. Since within the heart, BNP is mainly induced in cardiomyocytes by mechanical load, we investigated whether the natriuretic peptide/GC-A system also regulates angiogenesis accompanying load-induced cardiac hypertrophy. EC GC-A KO hearts showed diminished angiogenesis, mild fibrosis, and diastolic dysfunction. In vitro BNP/GC-A stimulated proliferation and migration of cultured microvascular endothelia by activating cGMP-dependent protein kinase I and phosphorylating vasodilator-stimulated phosphoprotein and p38 MAPK. We therefore conclude that BNP, produced by activated satellite cells within ischemic skeletal muscle or by cardiomyocytes in response to pressure load, regulates the regeneration of neighboring endothelia via GC-A. This paracrine communication might be critically involved in coordinating muscle regeneration/hypertrophy and angiogenesis.

Authors

Michaela Kuhn, Katharina Völker, Kristine Schwarz, Javier Carbajo-Lozoya, Ulrich Flögel, Christoph Jacoby, Jörg Stypmann, Martin van Eickels, Stepan Gambaryan, Michael Hartmann, Matthias Werner, Thomas Wieland, Jürgen Schrader, Hideo A. Baba

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Figure 7

BNP stimulates phosphorylation of VASP and p38 MAPK in primary cultured MLECs via the GC-A receptor.

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BNP stimulates phosphorylation of VASP and p38 MAPK in primary cultured ...
(A) BNP (10 and 100 nM, 5 minutes) increased cGMP in wild-type (control) but not GC-A–deficient MLECs. (B) Western blot analyses. GC-A protein was present in wild-type and absent in GC-A–deficient ECs. PKG I was present in MLECs of both genotypes, expression levels being significantly increased in GC-A–deficient cells. BNP (10 nM, 5 minutes) stimulated the phosphorylation of VASP at the PKG I preferred site in wild-type but not in GC-A KO MLECs (n = 3 in all experiments). (C) Western blot analyses showing the time-dependent changes in phosphorylated VASP and p38 in response to 10 nM BNP. Top: Representative immunoblots of phospho-VASP, phospho-p38, total p38, phospho-ERK1/2, and total ERK1/2. The expression of phospho-VASP in controls and GC-A KO was evaluated in 2 separate gels as indicated by the separating white line. Bottom: Protein levels of phospho-VASP and phospho-p38 were normalized to total p38 and those of phospho-ERK1/2 to total ERK1/2 and were calculated as fold relative to untreated cells (time 0). Phospho-VASP and phospho-p38 levels were significantly increased by BNP in control but not in GC-A–deficient MLECs (n = 3 experiments; *P < 0.05 vs. basal at 0 minutes). Phospho-ERK1/2 levels were not affected by BNP.