TGF-β1 stimulates movement of renal proximal tubular epithelial cells in a three-dimensional cell culture via an autocrine TGF-β2 production

Formin mDia1 contributes to migration and epithelial-mesenchymal transition of tubular epithelial cells exposed to TGF-β1

Renal tubular epithelial cells may undergo epithelial-mesenchymal transition (EMT) in response to stimuli, such as transforming growth factor (TGF)-β1, leading to myofibroblast activation and renal fibrosis. The formin mDia1 is required for nucleation and polymerization of actin and the microtubule cytoskeleton. The present study sought to explore the role of mDia1 in EMT of tubular epithelial cells. A rat model of unilateral ureteral obstruction (UUO) was established. The expression of TGF-β1, collagen I, collagen III, and mDia1 in the kidneys was examined at day 7 after surgery. The effect of mDia1 on EMT was explored in NRK-52E cells by exposing them to TGF-β1. Increased expression of TGF-β1, collagen I, collagen III, and mDia1 was found in obstructive kidneys of UUO model rats. Exposing rat tubular epithelial cells to TGF-β1 promoted collagen I and collagen III expression but had no effect on mDia1 expression. Silencing mDia1 expression impeded epithelial cell migration as well as reduced TGF-β1, collagen, and Profilin1 expression, whereas mDia1 overexpression exerted an opposite effect. Furthermore, mDia1 regulated the expression of vimentin, α-smooth muscle actin, and E-cadherin and focal adhesion-kinase (FAK)/Src activation through Profilin1. Inhibition of the mDia1 activator RhoA by fasudil reversed EMT, and FAK/Src activation induced by mDia1. In conclusion, mDia1 regulated tubular epithelial cell migration, collagen expression, and EMT in NRK-52E cells exposed to TGF-β1. Thus, suppression of mDia1 activation might be a strategy to counteract renal fibrosis.

Furin inhibition prevents hypoxic and TGFβ-mediated blood-brain barrier disruption

Hypoxic blood-brain barrier (BBB) dysfunction is a common feature of CNS diseases however mechanisms underlying barrier disturbance are still largely unknown. This study investigated the role of transforming growth factor β (TGFβ), a cytokine known to induce expression of the proprotein convertase Furin, in hypoxia-mediated barrier compromise. We show that exposure of brain endothelial cells (ECs) to hypoxia (1% O₂) rapidly stimulates their migration. Additional exogenous TGFβ (0.4 nM) exposure potentiated this effect and increased Furin expression in a TGFβ type I receptor activin-like kinase 5 (ALK5) - dependent manner (prevented by 10 μM SB431542). Furin inhibition prevented hypoxia-induced EC migration and blocked TGFβ-induced potentiation suggesting existence of a feedback loop. TGFβ and Furin were also critical for hypoxia-induced BBB dysfunction. TGFβ treatment aggravated hypoxia-induced BBB permeability but ALK5 or Furin blockade reversed injury-induced permeability changes. Thus during insult Furin compromises endothelial integrity by mediating the effects of TGFβ. Targeting the Furin or ALK5 pathway may offer novel therapeutic strategies for improving BBB stability and CNS function during disease.

Investigation of expression and effects of TGF-β1 and MMP-9 in lens epithelial cells of diabetic cataract rats

Expressions and effects of transforming growth factor- 1 (TGF-β1) and matrix metalloproteinase-9 (MMP-9) in lens epithelial cells (LECs) of diabetic cataract rats were investigated. A total of 40 female Sprague-Dawley rats were randomly divided into study and control group. Rats in study group were successfully modeled diabetic cataract rats, and rats in control group were normal rats. Immunohistochemical staining was used to determine positive and negative granules in cytoplasm, and image proplus image analysis system to calculate the integral optical density of the average positive area. Quantitative analysis was performed on TGF-β1 and MMP-9 in LECs of rats in study and control groups at the 2nd and 4th weekends. There were no statistically significant differences in length and age between the two groups of rats (P>0.05). Glucose concentration in the blood of rats in study group after modeling was significantly higher than that before modeling (P<0.001), and that after modeling was significantly higher in study group than that in control group (P<0.001). The expression of TGF-β1 protein in LECs of rats in study group at T2 (the 4th weekend) was significantly higher than that at T1 (the 2nd weekend) (P<0.001), and that of TGF-β1 protein was significantly higher in study group than that in control group at T1 and T2 (P<0.001). The expression of MMP-9 protein in LECs of rats in study group at T2 was significantly higher than that at T1 (P<0.001), and that of MMP-9 protein was significantly higher in study group than that in control group at T1 and T2 (P<0.001). The TGF-β1 expression was positively correlated with the MMP-9 expression in LECs of diabetic cataract rats (r=0.825, P<001). The increased expression of MMP-9 and TGF-β1 may play an important role in the occurrence and development of diabetic cataract.