MicroRNA-29b/142-5p contribute to the pathogenesis of biliary atresia by regulating the IFN-\u03b3 gene

Yifan Yang,Shan Zheng,Zhu Jin,Rui Dong,Gong Chen,Zhen Shen,Chao Zheng,Yijie Zheng,Yanlei Huang,Xiaoying Luo

doi:10.1038/s41419-018-0605-y

Abstract

Biliary atresia is one of the most common liver disease in infancy. The cause and pathogenesis remain largely unknown. This study aimed to investigate the potential regulatory effect of miR-29b/142-5p on IFN-γ gene methylation. miRNAs microarray was performed on four pairs of liver and blood specimens from biliary atresia and choledochal cysts. We found the overexpression of miR-142-5p and mRNA level of DNA methyltransferase (DNMT) 1, and miR-29b and DNMT3a/DNMT3b were significantly negatively correlated in biliary atresia livers. Meanwhile, the methylation of the LINE-1, ALU and SAT2 repetitive sequences and the IFN-γ promoter was lower, but the expression of IFN-γ was upregulated. After transfected with DNMTs siRNAs, downregulation of DNMTs exerted a significant hypomethylating effect on the repetitive sequences, which led to upregulation of IFN-γ in Jurkat cells. The direct interactions between miR-29b and DNMT3a/3b, and miR-142-5p and DNMT1 were identified using luciferase reporter assays. By transfecting mimics of miR-29b/142-5p into Jurkat cells, we found overexpression of miR-29b/142-5p markedly suppressed expression of DNMTs. Furthermore, the methylation of repetitive sequences and the IFN-γ promoter region were remarkably downregulated, and with elevated IFN-γ expression. After transfecting the miRNA inhibitors, the levels of DNMTs and the methylation of the IFN-γ gene promoter region was upregulated, while levels of IFN-γ were markedly suppressed. Our study suggested that miRNA-29b/142-5p overexpression and targeted inhibition of DNMTs expression resulted in decreased overall gene methylation and overexpression of the methylation-sensitive IFN-γ gene.

Highlights

Biliary atresia is one of the most common causes of obstructive jaundice and the most common liver disease in infancy
We found that the expression of miR-29b and miR-142-5p were remarkably upregulated (p < 0.01), and that the messenger RNA and protein levels of DNA methyltransferase (DNMT) were downregulated (p < 0.05) in biliary atresia cases (Fig. 1b)
We further investigated the methylation of the IFN-γ promoter, and found that the ratio of CpG sites decreased with an increased time of treatment in Jurkat cells (p < 0.001, Fig. 2d)

Summary

Introduction

Biliary atresia is one of the most common causes of obstructive jaundice and the most common liver disease in infancy. It is characterized by progressive destructive hepatobiliary inflammation and fibrous obstruction, intrahepatic biliary fibrosis atresia, and eventually cirrhosis[1, 2]. Ifn-γ-/- mice that were infected with virus and recombinant IFN-γ showed symptoms of biliary atresia, similar to the wild-type mice injected with virus[7].

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