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Knockout of microRNA-21 reduces biliary hyperplasia and liver fibrosis in cholestatic bile duct ligated mice

View Article: PubMed Central - PubMed

ABSTRACT

Cholestasis is a condition that leads to chronic hepatobiliary inflammation, fibrosis, and eventually cirrhosis. Many microRNAs (miRs) are known to play a role in fibrosis progression; however, the role of miR-21 during cholestasis remains unknown. Therefore, the aim of this study was to elucidate the role of miR-21 during cholestasis-induced biliary hyperplasia and hepatic fibrosis. Wild-type (WT) and miR21−/− mice underwent sham or bile duct ligation (BDL) for 1 wk, before evaluating liver histology, biliary proliferation, hepatic stellate cell (HSC) activation, fibrotic response, and Smad-7 expression. In vitro, immortalized murine biliary cell lines (IMCL) and human hepatic stellate cell line (hHSC) were treated with either miR-21 inhibitor or control before analyzing proliferation, apoptosis, and fibrotic responses. In vivo, the levels of miR-21 were increased in total liver and cholangiocytes after BDL, and loss of miR-21 decreased the amount of BDL-induced biliary proliferation and intrahepatic biliary mass. Also, loss of miR-21 decreased BDL-induced HSC activation, collagen deposition, and expression of the fibrotic markers TGF-β1 and α-SMA. In vitro, IMCL and hHSCs treated with miR-21 inhibitor displayed decreased proliferation and expression of fibrotic markers and enhanced apoptosis when compared to control treated cells. Furthermore, mice lacking miR-21 show increased Smad-7 expression, which may be driving the decrease in biliary hyperplasia and hepatic fibrosis. During cholestatic injury miR-21 is increased and leads to increased biliary proliferation and hepatic fibrosis. Local modulation of miR-21 may be a therapeutic option for patients with cholestasis.

No MeSH data available.


Evaluation of Smad-7 expression. In total liver and isolated cholangiocytes from BDL WT mice there is increased decreased Smad-7, as shown by qPCR, when compared to Sham WT (A, B). However, total liver and isolated cholangiocytes from BDL miR-21−/− mice show increased Smad-7 when compared to BDL WT (A, B). n = 9 reactions from total RNA from 6 animals for qPCR. *p<0.05 vs. Sham WT; #p<0.05 vs. BDL WT.
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Figure 8: Evaluation of Smad-7 expression. In total liver and isolated cholangiocytes from BDL WT mice there is increased decreased Smad-7, as shown by qPCR, when compared to Sham WT (A, B). However, total liver and isolated cholangiocytes from BDL miR-21−/− mice show increased Smad-7 when compared to BDL WT (A, B). n = 9 reactions from total RNA from 6 animals for qPCR. *p<0.05 vs. Sham WT; #p<0.05 vs. BDL WT.

Mentions: Smad-7 has been reported as a target of miR-21 25, and since Smad signaling is involved in the promotion of hepatic fibrosis in both cholangiocytes and HSCs during models of cholestasis 16, 36 we evaluated the expression of Smad-7 in our model. In BDL WT mice there was decreased expression of Smad-7 in both total liver and isolated cholangiocytes when compared to Sham WT (Figure 8A and 8B); however, BDL miR-21−/− mice showed increased Smad-7 when compared to BDL WT (Figure 8A and 8B). No significant changes in these factors were noted in Sham miR-21−/− when compared to Sham WT. This data demonstrates that miR-21 can regulate Smad-7 within cholangiocytes during cholestasis.


Knockout of microRNA-21 reduces biliary hyperplasia and liver fibrosis in cholestatic bile duct ligated mice
Evaluation of Smad-7 expression. In total liver and isolated cholangiocytes from BDL WT mice there is increased decreased Smad-7, as shown by qPCR, when compared to Sham WT (A, B). However, total liver and isolated cholangiocytes from BDL miR-21−/− mice show increased Smad-7 when compared to BDL WT (A, B). n = 9 reactions from total RNA from 6 animals for qPCR. *p<0.05 vs. Sham WT; #p<0.05 vs. BDL WT.
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Related In: Results  -  Collection

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Figure 8: Evaluation of Smad-7 expression. In total liver and isolated cholangiocytes from BDL WT mice there is increased decreased Smad-7, as shown by qPCR, when compared to Sham WT (A, B). However, total liver and isolated cholangiocytes from BDL miR-21−/− mice show increased Smad-7 when compared to BDL WT (A, B). n = 9 reactions from total RNA from 6 animals for qPCR. *p<0.05 vs. Sham WT; #p<0.05 vs. BDL WT.
Mentions: Smad-7 has been reported as a target of miR-21 25, and since Smad signaling is involved in the promotion of hepatic fibrosis in both cholangiocytes and HSCs during models of cholestasis 16, 36 we evaluated the expression of Smad-7 in our model. In BDL WT mice there was decreased expression of Smad-7 in both total liver and isolated cholangiocytes when compared to Sham WT (Figure 8A and 8B); however, BDL miR-21−/− mice showed increased Smad-7 when compared to BDL WT (Figure 8A and 8B). No significant changes in these factors were noted in Sham miR-21−/− when compared to Sham WT. This data demonstrates that miR-21 can regulate Smad-7 within cholangiocytes during cholestasis.

View Article: PubMed Central - PubMed

ABSTRACT

Cholestasis is a condition that leads to chronic hepatobiliary inflammation, fibrosis, and eventually cirrhosis. Many microRNAs (miRs) are known to play a role in fibrosis progression; however, the role of miR-21 during cholestasis remains unknown. Therefore, the aim of this study was to elucidate the role of miR-21 during cholestasis-induced biliary hyperplasia and hepatic fibrosis. Wild-type (WT) and miR21&minus;/&minus; mice underwent sham or bile duct ligation (BDL) for 1 wk, before evaluating liver histology, biliary proliferation, hepatic stellate cell (HSC) activation, fibrotic response, and Smad-7 expression. In vitro, immortalized murine biliary cell lines (IMCL) and human hepatic stellate cell line (hHSC) were treated with either miR-21 inhibitor or control before analyzing proliferation, apoptosis, and fibrotic responses. In vivo, the levels of miR-21 were increased in total liver and cholangiocytes after BDL, and loss of miR-21 decreased the amount of BDL-induced biliary proliferation and intrahepatic biliary mass. Also, loss of miR-21 decreased BDL-induced HSC activation, collagen deposition, and expression of the fibrotic markers TGF-&beta;1 and &alpha;-SMA. In vitro, IMCL and hHSCs treated with miR-21 inhibitor displayed decreased proliferation and expression of fibrotic markers and enhanced apoptosis when compared to control treated cells. Furthermore, mice lacking miR-21 show increased Smad-7 expression, which may be driving the decrease in biliary hyperplasia and hepatic fibrosis. During cholestatic injury miR-21 is increased and leads to increased biliary proliferation and hepatic fibrosis. Local modulation of miR-21 may be a therapeutic option for patients with cholestasis.

No MeSH data available.