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Effect of miR-34a in regulating steatosis by targeting PPARα expression in nonalcoholic fatty liver disease.

Ding J, Li M, Wan X, Jin X, Chen S, Yu C, Li Y - Sci Rep (2015)

Bottom Line: The upregulation of miR-34a resulted in the downregulation of hepatic PPARα and SIRT1 that are the direct targets of miR-34a.Activation of the central metabolic sensor AMPK was also increased.The miR-34a inhibitor suppressed lipid accumulation and improved the degree of steatosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious Diseases, Hangzhou First People's Hospital, No. 261 Huansha Road, Hangzhou 310006, Zhejiang Province, China.

ABSTRACT
MicroRNA-34a (miR-34a) is thought to be involved in nonalcoholic fatty liver disease (NAFLD). However, the association between altered expression of miR-34a and the pathophysiological features of NAFLD remains unclear. Here, we investigated the mechanisms by which miR-34a influences NAFLD through the PPARα-related pathway. Real-time quantitative PCR, western blotting and other assays kit were used to investigate the expression and function of miR-34a in an NAFLD model. Cultured cells transfected with miR-34a inhibitor and C57BL/6 mice injected with the miR-34a inhibitor through vein tail were conducted for the effects of miR-34a on its target. MiR-34a levels were significantly upregulated in steatosis-induced hepatocytes and in liver tissues of high-fat diet-fed mice. The upregulation of miR-34a resulted in the downregulation of hepatic PPARα and SIRT1 that are the direct targets of miR-34a. Silencing miR-34a led to an initially increased expression of PPARα, SIRT1 and PPARα's downstream genes. Activation of the central metabolic sensor AMPK was also increased. The miR-34a inhibitor suppressed lipid accumulation and improved the degree of steatosis. Taken together, our data indicated that decreased expression of miR-34a potentially contributes to altered lipid metabolism in NAFLD. Downregulation of miR-34a may be a therapeutic strategy against NAFLD by regulating its target PPARα and SIRT1.

No MeSH data available.


Related in: MedlinePlus

Inhibition of miR-34a attenuated hepatic steatosis and plasma AST levels in HFD-fed mice.(A) The miR-34a inhibitor markedly reduced the miR-34a expression levels in mice. (B) H&E-stained liver sections from mice fed with HFD treated with NC or miR-34a inhibitor (400×). (C) Oil red O staining of liver tissues fed with HFD, HFD treated with NC or miR-34a inhibitor respectively (400×). (D) Influence of miR-34a inhibitor on liver TG levels induced by HFD. (E) Influence of miR-34a inhibitor on liver weight/body weight ratio (liver index) induced by HFD. Representative results from three independent experiments are shown. Data are mean ± standard deviation in A, D and E. *P < 0.05.
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f2: Inhibition of miR-34a attenuated hepatic steatosis and plasma AST levels in HFD-fed mice.(A) The miR-34a inhibitor markedly reduced the miR-34a expression levels in mice. (B) H&E-stained liver sections from mice fed with HFD treated with NC or miR-34a inhibitor (400×). (C) Oil red O staining of liver tissues fed with HFD, HFD treated with NC or miR-34a inhibitor respectively (400×). (D) Influence of miR-34a inhibitor on liver TG levels induced by HFD. (E) Influence of miR-34a inhibitor on liver weight/body weight ratio (liver index) induced by HFD. Representative results from three independent experiments are shown. Data are mean ± standard deviation in A, D and E. *P < 0.05.

Mentions: To further evaluate the effect of miR-34a on HFD-induced hepatic steatosis in vivo, we adopted the ‘lentiviral tail vein injection’ method to deliver the miR-34a inhibitor into mouse hepatocytes. C57BL/6 mice that had been fed with a high-fat diet for 4 weeks were treated with 100 μl saline, miR-34a inhibitor at 2*107 TU of pLenti6.3/TO/V5 vector or NC. There was an approximately 63% reduction in the miR-34a level in mouse liver tissues (Fig. 2A). As shown in Fig. 2B H&E staining and Fig. 2C Oil Red O staining demonstrated that the miR-34a inhibitor attenuated the steatosis degree in the liver tissues. In accordance with morphological findings, hepatic TG was reduced by 35% in mice injected with the miR-34a inhibitor, compared with the NC after 4 weeks of an HFD diet (P < 0.05) (Fig. 2D). Furthermore, liver weight/body weight ratio (liver index) reduced significantly in the miR-34a inhibitor groups (Fig. 2E). Liver inflammation or fibrosis was not significant observed in these experimental groups.


Effect of miR-34a in regulating steatosis by targeting PPARα expression in nonalcoholic fatty liver disease.

Ding J, Li M, Wan X, Jin X, Chen S, Yu C, Li Y - Sci Rep (2015)

Inhibition of miR-34a attenuated hepatic steatosis and plasma AST levels in HFD-fed mice.(A) The miR-34a inhibitor markedly reduced the miR-34a expression levels in mice. (B) H&E-stained liver sections from mice fed with HFD treated with NC or miR-34a inhibitor (400×). (C) Oil red O staining of liver tissues fed with HFD, HFD treated with NC or miR-34a inhibitor respectively (400×). (D) Influence of miR-34a inhibitor on liver TG levels induced by HFD. (E) Influence of miR-34a inhibitor on liver weight/body weight ratio (liver index) induced by HFD. Representative results from three independent experiments are shown. Data are mean ± standard deviation in A, D and E. *P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4557122&req=5

f2: Inhibition of miR-34a attenuated hepatic steatosis and plasma AST levels in HFD-fed mice.(A) The miR-34a inhibitor markedly reduced the miR-34a expression levels in mice. (B) H&E-stained liver sections from mice fed with HFD treated with NC or miR-34a inhibitor (400×). (C) Oil red O staining of liver tissues fed with HFD, HFD treated with NC or miR-34a inhibitor respectively (400×). (D) Influence of miR-34a inhibitor on liver TG levels induced by HFD. (E) Influence of miR-34a inhibitor on liver weight/body weight ratio (liver index) induced by HFD. Representative results from three independent experiments are shown. Data are mean ± standard deviation in A, D and E. *P < 0.05.
Mentions: To further evaluate the effect of miR-34a on HFD-induced hepatic steatosis in vivo, we adopted the ‘lentiviral tail vein injection’ method to deliver the miR-34a inhibitor into mouse hepatocytes. C57BL/6 mice that had been fed with a high-fat diet for 4 weeks were treated with 100 μl saline, miR-34a inhibitor at 2*107 TU of pLenti6.3/TO/V5 vector or NC. There was an approximately 63% reduction in the miR-34a level in mouse liver tissues (Fig. 2A). As shown in Fig. 2B H&E staining and Fig. 2C Oil Red O staining demonstrated that the miR-34a inhibitor attenuated the steatosis degree in the liver tissues. In accordance with morphological findings, hepatic TG was reduced by 35% in mice injected with the miR-34a inhibitor, compared with the NC after 4 weeks of an HFD diet (P < 0.05) (Fig. 2D). Furthermore, liver weight/body weight ratio (liver index) reduced significantly in the miR-34a inhibitor groups (Fig. 2E). Liver inflammation or fibrosis was not significant observed in these experimental groups.

Bottom Line: The upregulation of miR-34a resulted in the downregulation of hepatic PPARα and SIRT1 that are the direct targets of miR-34a.Activation of the central metabolic sensor AMPK was also increased.The miR-34a inhibitor suppressed lipid accumulation and improved the degree of steatosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Infectious Diseases, Hangzhou First People's Hospital, No. 261 Huansha Road, Hangzhou 310006, Zhejiang Province, China.

ABSTRACT
MicroRNA-34a (miR-34a) is thought to be involved in nonalcoholic fatty liver disease (NAFLD). However, the association between altered expression of miR-34a and the pathophysiological features of NAFLD remains unclear. Here, we investigated the mechanisms by which miR-34a influences NAFLD through the PPARα-related pathway. Real-time quantitative PCR, western blotting and other assays kit were used to investigate the expression and function of miR-34a in an NAFLD model. Cultured cells transfected with miR-34a inhibitor and C57BL/6 mice injected with the miR-34a inhibitor through vein tail were conducted for the effects of miR-34a on its target. MiR-34a levels were significantly upregulated in steatosis-induced hepatocytes and in liver tissues of high-fat diet-fed mice. The upregulation of miR-34a resulted in the downregulation of hepatic PPARα and SIRT1 that are the direct targets of miR-34a. Silencing miR-34a led to an initially increased expression of PPARα, SIRT1 and PPARα's downstream genes. Activation of the central metabolic sensor AMPK was also increased. The miR-34a inhibitor suppressed lipid accumulation and improved the degree of steatosis. Taken together, our data indicated that decreased expression of miR-34a potentially contributes to altered lipid metabolism in NAFLD. Downregulation of miR-34a may be a therapeutic strategy against NAFLD by regulating its target PPARα and SIRT1.

No MeSH data available.


Related in: MedlinePlus