Title: Hyperoxia and transforming growth factor β1 signaling in the post-ischemic mouse heart.
Authors: Li, Yuanjing; Cai, Ming; Sun, Qinghua; Liu, Zhenguo; Cardounel, Arturo J; Swartz, Harold M; He, Guanglong
Published In Life Sci, (2013 Mar 21)
Abstract: Following ischemic injury, myocardial healing and remodeling occur with characteristic myofibroblast trans-differentiation and scar formation. The current study tests the hypothesis that hyperoxia and nitric oxide (NO) regulate TGF-β1 signaling in the post-ischemic myocardium.C57BL/6 wild-type (WT), endothelial and inducible nitric oxide synthase knockout (eNOS(-/-) and iNOS(-/-)) mice were subjected to 30-min left anterior descending coronary artery occlusion followed by reperfusion. Myocardial tissue oxygenation was monitored with electron paramagnetic resonance oximetry. Protein expressions of TGF-β1, receptor-activated small mothers against decapentaplegic homolog (Smad), p21 and α-smooth muscle actin (α-SMA) were measured with enzyme-linked immunosorbent assay (ELISA), Western immunoblotting, and immunohistochemical staining.There was a hyperoxic state in the post-ischemic myocardial tissue. Protein expressions of total and active TGF-β1, p-Smad2/3 over t-Smad2/3 ratio, p21, and α-SMA were significantly increased in WT mice compared to Sham control. Knockout of eNOS or iNOS further increased protein expression of these signals. The expression of α-SMA was more abundant in the infarct of eNOS(-/-) and iNOS(-/-) mice than WT mice. A protein band indicating nitration of TGF-β type-II receptor (TGFβRII) was observed from WT heart. Carbogen (95% O2 plus 5% CO2) treatment increased the ratio of p-Smad2/t-Smad2, which was inhibited by 10006329 EUK (EUK134) and sodium nitroprusside (SNP). In conclusion, hyperoxia up-regulated and NO/ONOO(-) inhibited cardiac TGF-β1 signaling and myofibroblast trans-differentiation.These findings may provide new insights in myocardial infarct healing and repair.
PubMed ID: 23352974
MeSH Terms: Actins/metabolism; Animals; Blotting, Western; Cell Differentiation/drug effects; Electron Spin Resonance Spectroscopy; Enzyme-Linked Immunosorbent Assay; Hyperoxia/etiology; Hyperoxia/metabolism*; Immunohistochemistry; Mice; Mice, Inbred C57BL; Mice, Knockout; Myocardial Ischemia/complications*; Myofibroblasts/cytology; Nitric Oxide Synthase Type II/genetics; Nitric Oxide Synthase Type III/genetics; Nitric Oxide/metabolism*; Oximetry; Signal Transduction/physiology*; Smad2 Protein/metabolism; Smad3 Protein/metabolism; Transforming Growth Factor beta1/metabolism*