The transforming growth factor-β1 (TGF-β1)/Smad3 signal pathway is related to mutiple physiological and pathological generation mechanism of human being. Up to date, however, the spacial and time information on the phosphorylated Smad3 is still unclear. In this study, the process of Smad3 phosphorylation was observed under the physiological state in the living cells. Firstly, the ECFP-Smad3-Citrine (Smad3 biosensor) fusion protein expression vector was constructed and identified. Then the Smad3 biosensor was transfected into 293T cells. The transfection efficiency and the expressions of fusion proteins were observed in 24 hours. Thirdly, Smad3 biosensor flurorescence resonance energy transfer (FRET) was observed with the inversion fluorescence microscope and measured by the MetaFlour FRET 4.6 software. Smad3 biosensor transfection efficiency was nearly 40% and the fusion protein was seen under the fluorescence microscope. The FRET ratio of Smad3 biosensor in living 293T cells was decreased after 10 minutes incubation with the ligand of TGF-β1. The period of decreasing CFP and enhancing Citrine signals was about 300 seconds. With the technology of FRET, the TGF-β1/Smad3 signal pathway could be real time monitored dynamically under the physiological condition in living cells.
This study is aimed to investigate the effects of mechanical stretch on the expression of transforming growth factor-β1 (TGF-β1) and fibroblast growth factor-2 (FGF-2), and the signaling pathway in human bronchial epithelioid (16HBE) cells under mechanical stretch. Using loading device with flexible substrate (FX-4000T) to stretch 16HBE cells, we found that the stretching elongation was 15%, at frequency of 1 Hz, stretching for 0.5 h, 1 h, 1.5 h and 2 h. Choosing the higher expression of TGF-β1, FGF-2 and Ca2+ group to carry out intervention experiments, we used the cells pretreated with canonical transient receptor potential 1 (TRPC1) channel antagonist SKF96365, protein kinase C (PKC) inhibitor HA-100, and thereafter mechanical stretch to interpose. Compared with those in the blank control group, TGF-β1 and FGF-2' protein and mRNA, intracellular Ca2+ fluorescence intensity were higher, and the differences were statistically significant (P < 0.05) at the 4 time points, 0.5 h, 1 h, 1.5 h and 2 h. At 0.5 h, the increasing rate was the highest. TGF-β1 protein and mRNA, FGF-2 protein and mRNA, intracellular Ca2+ luorescence intensity in the stretch+SKF96365 and stretch+HA-100 intervented group were decreased, the differences were statistically significant than those in 0.5 h stretch group (P < 0.05) without intervention. The expression of TGF-β1, FGF-2 was up-regulated in 16HBE cells under mechanical stretch, PKC, TRPC1, and Ca2+ may participate in the signal path.
Long non-coding RNA (lncRNA) Dnm3os plays a critical role in peritendinous fibrosis and pulmonary fibrosis, but its role in the process of cardiac fibrosis is still unclear. Therefore, we carried out study by using the myocardial fibrotic tissues obtained by thoracic aortic constriction (TAC) in an early study of our group, and the in vitro cardiac fibroblast activation model induced by transforming growth factor-β1 (TGF-β1). Quantitative real-time polymerase chain reaction (RT-qPCR), Western blot, and collagen gel contraction test were used to identify the changes of activation phenotype and the expression of Dnm3os in cardiac fibroblasts. Small interfering RNA was used to silence Dnm3os to explore its role in the activation of cardiac fibroblasts. The results showed that the expression of Dnm3os was increased significantly in myocardial fibrotic tissues and in the activated cardiac fibroblasts. And the activation of cardiac fibroblasts could be alleviated by Dnm3os silencing. Furthermore, the TGF-β1/Smad2/3 pathway was activated during the process of cardiac fibroblasts activation, while was inhibited after silencing Dnm3os. The results suggest that Dnm3os silencing may affect the process of cardiac fibroblast activation by inhibiting TGF-β1/Smad2/3 signal pathway. Therefore, interfering with the expression of lncRNA Dnm3os may be a potential target for the treatment of cardiac fibrosis.