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 3

Immunohistochemistry on serial sections demonstrates expression of BNP in activated satellite cells of the ischemic hind limb.

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Immunohistochemistry on serial sections demonstrates expression of BNP i...
(A) Twenty-four hours after ischemia. Arrows on H&E-stained sections indicate necrosis of muscle fibers, surrounded by CD45-positive leukocytes. Only a few quiescent Myf5-positive satellite cells (lower left, arrow) are detected. None of these cell types contains immunoreactive BNP. (B) Three days after ischemia. H&E staining shows activated satellite cells with enlarged vesicular nuclei and basophilic cytoplasm (upper left, white arrows), which express Myf5 in nuclei and to a lesser extent in cytoplasm. These activated satellite cells contain immunoreactive BNP in their cytoplasm (upper right, white arrows). Clusters of satellite cells are surrounded by CD45-positive inflammatory cells but are themselves CD45-negative (lower right, white arrows). The boxed regions within the main panels denote a cluster of satellite cells at the original (×400) and at higher magnification (×800). (C) Two weeks after ischemia. H&E stainings demonstrate regenerating muscle fibers with centrally located nuclei (upper left, white arrows). Only a few quiescent Myf5-positive satellite cells and CD45-positive leukocytes are detected (lower panels, black arrows). No specific BNP staining is visible (upper right). (D) Nonischemic skeletal muscle of the contralateral limb shows vital muscle fibers without enhanced cellularity (H&E). Few quiescent satellite cells with Myf5 in nuclei are detected (lower left, black arrows). Leukocytes are absent. No specific BNP staining is visible (upper right). Original magnification for all panels, ×400.