Effect of mini-tyrosyl-tRNA synthetase/mini-tryptophanyl-tRNA synthetase on ischemic angiogenesis in rats: proliferation and migration of endothelial cells.

The purpose of this study was to determine the mechanism of mini-tyrosyl-tRNA synthetase/mini-tryptophanyl-tRNA synthetase (mini-TyrRS/mini-TrpRS) on ischemic angiogenesis in rats with acute myocardial infarction and proliferation, migration, potential signaling pathways of rat coronary venular endothelial cells (RCVECs). The effects of mini-TyrRS/mini-TrpRS on RCVECs proliferation were evaluated using the MTT colorimetric assay. Cell migration was assayed using a modified Boyden chamber technique. The potential involvement of Erk and PI3K signaling pathways was explored using selective chemical inhibitor or Western-blot analysis. Left coronary artery ligation was used to establish the model of acute myocardial infarction in rats (Sprague-Dawley male rats, 200-250 g, 2-3 months old), 20 μl of mini-TyrRS, mini-TrpRS, or PBS (vehicle) was injected subcutaneously every 12 h. The rats were randomly divided into four experimental groups: sham operated group; coronary artery ligation (CAL); CAL + mini-TyrRS (20 μl, twice daily, 600 μg kg(-1) day(-1)); and CAL + mini-TrpRS (20 μl, twice daily, 600 μg kg(-1) day(-1)). The experiment was carried out at four time points on the 3rd, 7th, 14th, and 28th day after ligation. To determine whether mini-TyrRS/mini-TrpRS affected the angiogenesis activity of rats with myocardial infarction, we measured the myocardial infarction size by TTC staining, and microvessel density (MVD) was determined by CD34 staining. The results show that proliferation and migration in RCVECs could be promoted by mini-TyrRS at concentrations of 1-100 μg/ml, and inhibited by mini-TrpRS. Phospho-PI3-kinase and Erk expression increased significantly when mini-TyrRS was added, but could be attenuated by mini-TrpRS. Compared to the CAL group, the myocardial infarction size of the mini-TyrRS group at the 3rd, 7th, 14th, and 28th day were decreased, while mini-TrpRS increased, but only in days 14 and 28 was there a significant difference. Except that, the microvessel density of RCVECs was promoted in mini-TyrRS group but inhibited in the mini-TrpRS group. These results indicated that angiogenesis could be either stimulated by mini-TyrRS or inhibited by mini-TrpRS.