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Hepatic miR-29ab1 expression modulates chronic hepatic injury.

ABSTRACT: MicroRNAs (miRNAs) are small, regulatory non-coding RNAs that have potent effects on gene expression. Several miRNA are deregulated in cellular processes involved in human liver diseases and regulation of cellular processes. Recent studies have identified the involvement of miR-29 in hepatic fibrosis and carcinogenesis. Although several targets of miR-29 have been identified, there is limited information regarding the cell-type specific roles of miR-29 in the liver, and we sought to evaluate the role of this miRNA in hepatic pathobiology. We report the generation of a tissue-specific knockout mouse to evaluate the role of miR-29 in hepatic fibrosis and carcinogenesis in response to injury. We hypothesized that miR-29 contributes to the hepatocyte driven response to chronic cellular injury that results in fibrosis. In support of this hypothesis, fibrosis and mortality were enhanced in miR29 knockout mice in response to carbon tetrachloride. Genome-wide gene expression analysis identified an over-representation of genes associated with fibrosis. The oncofetal RNA H19 was modulated in a miR-29 dependent manner following exposure to carbon tetrachloride in vivo. The impact of a hepatocyte specific miR-29 knockout on survival following chronic hepatic injury in vivo implicates this miRNA as a potential target for intervention. These results provide evidence of the involvement of miR-29 in chronic hepatic injury, and suggest a role for deregulated hepatocyte expression of miR-29 in the response to hepatic injury, fibrosis and carcinogenesis.

SUBMITTER: Kogure T

PROVIDER: S-EPMC3923513 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature

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Hepatic miR-29ab1 expression modulates chronic hepatic injury.

Kogure Takayuki T Costinean Stefan S Yan Irene I Braconi Chiara C Croce Carlo C Patel Tushar T

Journal of cellular and molecular medicine 20121101 11

MicroRNAs (miRNAs) are small, regulatory non-coding RNAs that have potent effects on gene expression. Several miRNA are deregulated in cellular processes involved in human liver diseases and regulation of cellular processes. Recent studies have identified the involvement of miR-29 in hepatic fibrosis and carcinogenesis. Although several targets of miR-29 have been identified, there is limited information regarding the cell-type specific roles of miR-29 in the liver, and we sought to evaluate the ...[more]

PMID: 22469499

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Project description:Rationale: An improved understanding of thyroid hormone (TH) action on cholesterol metabolism will facilitate the identification of novel therapeutic targets for hypercholesterolemia. TH-regulated microRNAs (miRNAs) have been implicated in TH-controlled biological processes; however, whether and how TH-regulated miRNAs mediate the cholesterol-lowering effect of TH remains unclear. Our aim was to identify TH-regulated microRNAs that have cholesterol-lowering effects and explore the underlying mechanism. Method: Microarray and RNA-seq were performed to identify TH-regulated microRNAs and the genes regulated by mmu-miR-378-3p (miR-378) in the liver of mice, respectively. Recombinant adenoviruses encoding miR-378, Mafg, and shRNA for Mafg, antagomiR-378, liver-specific miR-378 transgenic mice, and miR-378 knockout mice were employed to investigate the roles of hepatic miR-378 and MAFG in cholesterol and bile acid homeostasis. The levels of bile salt species were determined by using UFLC-Triple-time of flight/MS. Results: Here, we show that hepatic miR-378 is positively regulated by TH. Transient overexpression of miR-378 in the liver of mice reduces serum cholesterol levels, accompanied with an increase in the expression of key enzymes in primary bile acid synthetic pathways and corresponding increases in biliary and fecal bile acid levels. Consistently, liver-specific miR-378 transgenic mice with moderate overexpression of hepatic miR-378 display decreased serum cholesterol levels and resistance to diet-induced hypercholesterolemia, while mice lacking miR-378 exhibit defects in bile acid and cholesterol homeostasis. Mechanistically, hepatic miR-378 regulates the expression of key enzymes in both classic and alternative bile acid synthetic pathways through MAFG, a transcriptional repressor, thereby modulating bile acid and cholesterol metabolism. Conclusions: TH-responsive hepatic miR-378 is capable of modulating serum cholesterol levels by regulating both the classic and alternative BA synthetic pathways. Our study not only identifies a previously undescribed role of hepatic miR-378 but also provides new cholesterol-lowering approaches.

Project description:BackgroundSevoflurane can protect organs from ischemia-reperfusion (IR) injury, but the mechanism is still unclear. MicroRNA-122 (miR-122) is a liver-specific microRNA (miRNA) and regulates liver function. Therefore, this study aims to elucidate the relationship between the protective effect of sevoflurane and miR-122 in liver IR injury.MethodsWistar rats were divided into the following groups: sham, IR, IR + sevoflurane, IR + miR-122 antagomir, and IR + miR-122 antagomir + sevoflurane. Hematoxylin and eosin (H&E) staining and Suzuki score were used to evaluate the pathological damage of the liver. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10 in the serum and the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and nitric oxide (NO) in the liver homogenate supernatant were detected by using the corresponding kit. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) and flow cytometry was applied to evaluate the apoptosis of liver tissues. The expression of nuclear factor E2-related factor 2 (Nrf2), miR-122, p53, and HO-1 in liver tissue was evaluated by using immunohistochemistry, qRT-PCR, and western blot as needed.ResultsCompared to the IR group, the sevoflurane post-treatment or miR-122 antagomir groups showed improved liver injury, decreased Suzuki score, inhibited the levels of AST, ALT, LDH, MDA, NO, TNF-α, IL-1β, and IL-6, increased levels of SOD, IL-10, and inhibited hepatocyte apoptosis. Regarding the molecular mechanism, sevoflurane post-treatment fostered the expression of HO-1, promoted the transport of Nrf2 from cytoplasm to the nucleus, and decreased the expression of miR-122 and p53. The combined use of miR-122 antagomir and sevoflurane enhanced the protective effect of miR-122 antagomir in liver injury in IR rats.ConclusionsSevoflurane protected the liver from IR damage by regulating the miR-122/Nrf2/HO-1 pathway.

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Hepatic miR-29ab1 expression modulates chronic hepatic injury.

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Hepatic miR-29ab1 expression modulates chronic hepatic injury.

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