Angiotensin II stimulates endothelial NO synthase phosphorylation in thoracic aorta of mice with abdominal aortic banding via type 2 receptor.
Abdominal aortic banding in mice induces upregulation of angiotensin II (Ang II) type 2 (AT2) receptors in the pressure-overloaded thoracic aorta. To clarify mechanisms underlying the vascular AT2 receptor-dependent NO production, we measured aortic levels of endothelial NO synthase (eNOS), eNOS phosphorylated at Ser633 and Ser1177, protein kinase B (Akt), and Akt phosphorylated at Ser473 in thoracic aortas of mice after banding. Total eNOS, both forms of phosphorylated eNOS, Akt, and phosphorylated Akt levels, as well as cGMP contents, were significantly increased 4 days after banding. The administration of PD123319 (an AT2 receptor antagonist) or icatibant (a bradykinin B2 receptor antagonist) abolished the banding-induced upregulation of both forms of phosphorylated eNOS, as well as elevation of cGMP, but did not affect the upregulation of eNOS, Akt, and phosphorylated Akt. In the in vitro experiments using aortic rings prepared from banded mice, Ang II produced significant increases in both forms of phosphorylated eNOS, as well as cGMP, and these effects were blocked by PD123319 and icatibant. Ang II-induced eNOS phosphorylation and cGMP elevation in aortic rings were inhibited by protein kinase A (PKA) inhibitors H89 and KT5720 but not by phosphatidylinositol 3-kinase inhibitors wortmannin and LY24002. The contractile response to Ang II was attenuated in aortic rings from banded mice via AT2 receptor, and this attenuation was blocked by PKA inhibitors. These results suggest that the activation of AT2 receptor by Ang II induces phosphorylation of eNOS at Ser633 and Ser1177 via a PKA-mediated signaling pathway, resulting in sustained activation of eNOS.
Yayama
Katsutoshi
K
Laboratory of Cardiovascular Pharmacology, Department of Biopharmaceutical Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan.
Hiyoshi
Hiromi
H
Imazu
Daichi
D
Okamoto
Hiroshi
H
D000804:Angiotensin II / Q000008:administration & dosage / Q000502:physiology*; D000818:Animals; D001012:Aorta, Abdominal / Q000502:physiology*; D001013:Aorta, Thoracic / Q000201:enzymology* / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D004730:Endothelium, Vascular / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009119:Muscle Contraction / Q000502:physiology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology; D044139:Receptor, Angiotensin, Type 2 / Q000096:biosynthesis / Q000502:physiology*; D012694:Serine / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
D010750:Phosphoproteins; D044139:Receptor, Angiotensin, Type 2; D000804:Angiotensin II; D012694:Serine; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases