The role of hedgehog signaling pathway in transforming growth factor beta1-induced myofibroblast transdifferentiation / 中国组织工程研究

ABSTRACT

BACKGROUND: In recent years, increasing studies have shown that abnormally activated Hedghog signaling pathway is widely involved in the injury repair of systemic multi-tissue organ diseases, but its related role in myocardial fibrosis is still unclear. OBJECTIVE: To study the effect of blocking Hedgehog-Gli signaling pathway on epithelial-mesenchymal transition of myocardial fibroblasts induced by transforming growth factor-β1 (TGF-β1). METHODS: (1) Animal experiment The model of myocardial infarction in mice was established by left coronary artery ligature. The pathological changes of myocardial tissue were observed by hematoxylin-eosin staining and Masson staining at 3, 7, and 14 days after infarction. The mRNA, protein and spatio-temporal expressions of Gli1 at different time points were detected by RT-PC, western blot and immunofluorescence. The mRNA and protein expression changes of Gli1 before and after adding inhibitor were detected using RT-PCR and immunofluorescence. (2) Cell experiment The primary cultured myocardial fibroblasts of neonatal Sprague-Dawley rats were cultured by differential adherent method. The cultured myocardial fibroblasts were cultured with 0, 1, 5, and 10 μg/L TGF-β1 intervention. The expression of Gli1 mRNA and protein was detected by RT-PCR and western blot, respectively. Myocardial fibroblasts were induced by TGF-β1 of 10 μg/L for 24 hours, and the spatio-temporal expression of Gli1 protein and expression of epithelial-mesenchymal transition markers were detected by immunofluorescence. Gli1 and Smo in Hedgehog signaling pathway were specifically blocked by GANT61 and Cyclopamine for 24 hours, respectively, and 10 μg/L TGF-β1 was added. The mRNA expression level of Gli1 was detected by RT-PCR, and the spatio-temporal expression of Gli1 and expression of epithelial-mesenchymal transition markers were detected by immunofluorescence. RESULTS AND CONCLUSION: (1) Results of the animal experiment As the time after infarction prolonged, the mRNA and protein expression levels of Gli1 in the mouse myocardium gradually increased, but the mRNA and protein expressions of Gli1 in the infarcted tissue decreased after addition of the Hedgehog pathway specific blocker. (2) Results of the cell experiment After stimulation with TGF-β1, the epithelial mesenchyme of myocardial fibroblasts transformed into myofibroblasts (positive for a-SMA). As the intervention dose of TGF-β1 increased, the mRNA and protein expression of Gli1 gradually increased. After specifically blocking Gli1 and Smo in the Hedgehog signaling pathway for 24 hours, the mRNA and protein expression levels of Gli1 were inhibited, accompanied by the changes in the expression of E-Cadherin and Vimentin during epithelial-mesenchymal transition, indicating the existence of epithelial-mesenchymal transition. By the combination of in vivo and in vitro experiments, this study confirmed that the Hedgehog-Gli signal pathway is involved in the occurrence and development of myocardial fibrosis and myocardial fibroblast transdifferentiation.