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AIM To uncover the role of hepatocyte nuclear factor 4 alpha(HNF4α) in regulating hepatic expression of micro RNAs.METHODS Microarray and real-time PCR were used to determine hepatic expression of micro RNAs in young-adult mice lacking Hnf4α expression in liver(Hnf4α-Liv KO). Integrative genomics viewer software was used to analyze the public chromatin immunoprecipitation-sequencing datasets for DNA-binding of HNF4α, RNA polymerase-Ⅱ, and histone modifications to loci of micro RNAs in mouse liver and human hepatoma cells. Dual-luciferase reporter assay was conducted to determine effects of HNF4α on the promoters of mouse and human micro RNAs as well as effects of micro RNAs on the untranslated regions(3’UTR) of two genes in human hepatoma cells. RESULTS Microarray data indicated that most micro RNAs remained unaltered by Hnf4α deficiency in Hnf4α-Liv KO mice. However, certain liver-predominant micro RNAs were down-regulated similarly in young-adult male and female Hnf4α-Liv KO mice. The down-regulation of mi R-101, mi R-192, mi R-193 a, mi R-194, mi R-215, mi R-802, and mi R-122 as well as induction of mi R-34 and mi R-29 in male Hnf4α-Liv KO mice were confirmed by real-timePCR. Analysis of public chromatin immunoprecipitationsequencing data indicates that HNF4α directly binds to the promoters of mi R-101, mi R-122, mi R-194-2/mi R-192 and mi R-193, which is associated with histone marks of active transcription. Luciferase reporter assay showed that HNF4α markedly activated the promoters of mouse and human mi R-101b/mi R-101-2 and the mi R-194/mi R-192 cluster. Additionally, mi R-192 and mi R-194 significantly decreased activities of luciferase reporters for the 3’UTR of histone H3F3 and chromodomain helicase DNA binding protein 1(CHD1), respectively, suggesting that mi R-192 and mi R-194 might be important in chromosome remodeling through directly targeting H3F3 and CHD1.CONCLUSION HNF4α is essential for hepatic basal expression of a group of liver-enriched micro RNAs, including mi R-101, mi R-192, mi R-193 a, mi R-194 and mi R-802, through which HNF4α may play a major role in the post-transcriptional regulation of gene expression and maintenance of the epigenome in liver.
AIM To uncover the role of hepatocyte nuclear factor 4 alpha (HNF4α) in regulating hepatic expression of microRNAs. METHODS Microarray and real-time PCR were used to determine hepatic expression of microRNAs in young-adult mice lacking Hnf4α expression in liver (Hnf4α -Liv KO). Integrative genomics viewer software was used to analyze the public chromatin immunoprecipitation-sequencing datasets for DNA-binding of HNF4α, RNA polymerase-II, and histone modifications to loci of microRNAs in mouse liver and human hepatoma cells. Dual- luciferase reporter assay was conducted to determine effects of HNF4α on the promoters of mouse and human micro RNAs as well as effects as micro RNAs on the untranslated regions (3’UTR) of two genes in human hepatoma cells. RESULTS Microarray data indicated that most micro RNAs remained unaltered by Hnf4α deficiency in Hnf4α-Liv KO mice. However, certain liver-predominant microRNAs were down-regulated similarly in young-adult male and female Hnf4α-Liv K O mice. The down-regulation of mi R-101, mi R-192, mi R-193 a, mi R-194, mi R-215, mi R-802, and mi R-122 as well as induction of mi Analysis of public chromatin immunoprecipitation sequencing data indicates that HNF4α directly binds to the promoters of mi R-101, mi R-122, mi R-34 and mi R-29 in male Hnf4α-Liv KO mice were confirmed by real-time PCR. 194-2 / mi R-192 and mi R-193, which is associated with histone marks of active transcription. Luciferase reporter assay showed that HNF4α markedly activated the promoters of mouse and human mi R-101b / mi R-101-2 and The mi R-194 / mi R-192 cluster. Additionally, mi R-192 and mi R-194 deppectively activities of luciferase reporters for the 3’UTR of histone H3F3 and chromodomain helicase DNA binding protein 1 (CHD1), respectively, suggesting that mi R-192 and mi R-194 might be important in chromosome remodeling through directly targeting H3F3 and CHD1. CONCLUSION HNF4α is essential for hepatic basal expression of a group of liver-en riched micro RNAs, including mi R-101, mi R-192, mi R-193 a, mi R-194 and mi R-802, through which HNF4α may play a major role in the post-transcriptional regulation of gene expression and maintenance of the epigenome in liver.