MicroRNA-146a modulates TGF-beta1-induced hepatic stellate cell proliferation by targeting SMAD4.

Activation of hepatic stellate cells (HSC) plays a pivotal role in the development of hepatic fibrosis. Transforming growth factor-β1 (TGF-β1) is considered to be the main stimuli factor responsible for the activation of HSC. MicroRNAs (miRNAs) have recently been shown to regulate cell proliferation, differentiation, and apoptosis. The involvement of miRNAs and their roles in TGF-β1-induced HSC activation remains largely unknown. Our study found that the expression of miR-146a was downregulated in HSC in response to TGF-β1 stimulation in dose-dependent manner by one-step real-time quantitative PCR. Moreover, we sought to examine whether miR-146a became dysregulated in CCl(4)-induced hepatic fibrosis in rats. Our study revealed that miR-146a was downregulated in liver fibrotic tissues. In addition, The HSC transfected with miR-146a mimics exhibited attendated TGF-β1-induced α-smooth muscle actin (α-SMA) expression compared with the control. Furthermore, overexpression of miR-146a suppressed TGF-β-induced HSC proliferation, and increased HSC apoptosis. Bioinformatics analyses predict that SMAD4 is the potential target of miR-146a. MiR-146a overexpression in TGF-β1-treated HSC did not decrease target mRNA levels, but significantly reduced target protein expression. These results suggested that miR-146a may function as a novel regulator to modulate HSC activation during TGF-β1 induction by targeting SMAD4.

He Y ，Huang C ，Sun X ，Long XR ，Lv XW ，Li J ... -  《-》

The Epigenetically-Regulated microRNA-378a Targets TGF-β2 in TGF-β1-Treated Hepatic Stellate Cells.

In liver fibrosis, the activation of hepatic stellate cells (HSCs) is considered as a pivotal event. It is well known that transforming growth factor-β1 (TGF-β1) is the main stimuli factor responsible for HSC activation. microRNAs (miRNAs), regulating various biological processes, have recently been shown to be involved in HSC activation. A recent study reported that deficiency of miR-378a contributes to cardiac fibrosis via TGF-β1-dependent paracrine mechanism. However, the involvement of miR-378a and its roles in TGF-β1-induced HSC activation remains largely unknown. miR-378a expression was detected in TGF-β1-treated cells and patients with cirrhosis. Then, effects of miR-378a overexpression on cell proliferation and HSC activation were analyzed. We also analyzed the binding of miR-378a to the 3'-untranslated region of TGF-β2. In response to TGF-β1, miR-378a expression was down-regulated in a dose-dependent manner. miR-378a overexpression suppressed both cell proliferation and cell cycle in TGF-β1-treated LX-2 cells. Moreover, miR-378a overexpression inhibited TGF-β1-induced HSC activation including the reduction of α-smooth muscle actin (α-SMA) and type I collagen. Similarly, miR-378a resulted in a reduction in cell proliferation, and the expressions of α-SMA and Col1A1 in TGF-β1-treated primary HSCs. Notably, TGF-β2 was confirmed as a target of miR-378a by luciferase reporter assays. Interestingly, miR-378a promoter methylation may be responsible for miR-378a down-regulation in TGF-β1-treated LX-2 cells and TGF-β1-treated primary HSCs. Further studies confirmed that reduced miR-378a was associated with promoter methylation in patients with cirrhosis compared with healthy controls. Our results demonstrate that miR-378a expression is associated with its methylation status in TGF-β1-treated cells, and epigenetically-regulated miR-378a inhibits TGF-β1-induced HSC activation, at least in part, via TGF-β2.

Yu F ，Yang J ，Huang K ，Pan X ，Chen B ，Dong P ，Zheng J ... -  《-》

Epigenetically-Regulated MicroRNA-9-5p Suppresses the Activation of Hepatic Stellate Cells via TGFBR1 and TGFBR2.

Recently, microRNAs (miRNAs) have been demonstrated to act as regulators of activation of hepatic stellate cells (HSCs). It is well known that the main profibrogenic inducer transforming growth factor-β1 (TGF-β1) contributes to HSC activation, which is a key event in liver fibrosis. Increasing studies show that miR-9-5p is down-regulated in liver fibrosis and restoration of miR-9-5p limits HSC activation. However, the role of miR-9-5p in TGF-β1-induced HSC activation is still not clear. miR-9-5p expression was quantified using real-time PCR in chronic hepatitis B (CHB) patients and TGF-β1-treated LX-2 cells. In CHB patients, histological activity index (HAI) and fibrosis stages were assessed using the Ishak scoring system. Effects of miR-9-5p on liver fibrosis in vivo and in vitro were analyzed. Luciferase activity assays were performed to examine the binding of miR-9-5p to the 3'-untranslated region of type I TGF-β receptor (TGFBR1) as well as TGFBR2. Compared with healthy controls, miR-9-5p was reduced in CHB patients. There was a lower miR-9-5p expression in CHB patients with higher fibrosis scores or HAI scores. miR-9-5p was down-regulated by TGF-β1 in a dose-dependent manner. TGF-β1-induced HSC activation including cell proliferation, α-SMA and collagen expression was blocked down by miR-9-5p. Notably, miR-9-5p ameliorates carbon tetrachloride-induced liver fibrosis. As determined by luciferase activity assays, TGFBR1 and TGFBR2 were targets of miR-9-5p. Further studies demonstrated that miR-9-5p inhibited TGF-β1/Smads pathway via TGFBR1 and TGFBR2. Interestingly, promoter methylation was responsible for miR-9-5p down-regulation in liver fibrosis. The relationship between miR-9-5p expression and methylation was confirmed in CHB patients and TGF-β1-treated cells. Our results demonstrate that miR-9-5p could inhibit TGF-β1-induced HSC activation through TGFBR1 and TGFBR2. Loss of miR-9-5p is associated with its methylation status in liver fibrosis.

Yu F ，Chen B ，Fan X ，Li G ，Dong P ，Zheng J ... -  《-》

miR-144 regulates transforming growth factor-β1 iduced hepatic stellate cell activation in human fibrotic liver.

Liu Z ，Yi J ，Ye R ，Liu J ，Duan Q ，Xiao J ，Liu F ... -  《International Journal of Clinical and Experimental Pathology》

MicroRNA-146a modulates TGF-β1-induced phenotypic differentiation in human dermal fibroblasts by targeting SMAD4.

Liu Z ，Lu CL ，Cui LP ，Hu YL ，Yu Q ，Jiang Y ，Ma T ，Jiao DK ，Wang D ，Jia CY ... -  《-》