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RAW246.1 cells activation by internalized synthetic miR-122

ABSTRACT: Hepatic injury is often accompanied by pulmonary inflammation and tissue damage, but the underneath mechanism is not fully elucidated. Here we identify hepatic miR-122 as a culprit of pulmonary inflammation induced by various liver injuries. Analyses of acute and chronic liver injury mouse models confirm that liver dysfunction can cause pulmonary inflammation and tissue damage. Injured livers release large amounts of miR-122 in a microvesicle-independent manner into the circulation compared to normal livers. Circulating miR-122 is then preferentially transported to mouse lungs and taken up by alveolar macrophages, in which it binds toll-like receptor 7 (TLR7) and activates inflammatory responses. Depleting plasma miR-122 largely abolishes liver injury-induced pulmonary inflammation and tissue damage. Furthermore, alveolar macrophage activation by miR-122 is blocked by mutating the TLR7-binding UG-rich sequence on miR-122 or knocking out macrophage TLR7. Our findings reveal a novel causative role of hepatic miR-122 in liver injury-induced pulmonary dysfunction.

ORGANISM(S): Mus musculus

PROVIDER: GSE124360 | GEO | 2018/12/27

REPOSITORIES: GEO

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Project description:A defining feature of the mammalian liver is polyploidy, a numerical change in the entire complement of chromosomes. The first step of polyploidization involves cell division with failed cytokinesis. Although polyploidy is common, affecting ~90% of hepatocytes in mice and 50% in humans, the specialized role played by polyploid cells in liver homeostasis and disease remains poorly understood. The goal of this study was to identify novel signals that regulate polyploidization, and we focused on microRNAs (miRNAs). First, to test whether miRNAs could regulate hepatic polyploidy we examined livers from Dicer1 liver-specific knockout mice, which are devoid of mature miRNAs. Loss of miRNAs resulted in a 3-fold reduction in binucleate hepatocytes, indicating that miRNAs regulate polyploidization. Secondly, we surveyed age-dependent expression of miRNAs in wild-type mice and identified a subset of miRNAs, including miR-122, that is differentially expressed at 2-3 weeks, a period when extensive polyploidization occurs. Next, we examined Mir122 knockout mice and observed profound, life-long depletion of polyploid hepatocytes, proving that miR-122 is required for complete hepatic polyploidization. Moreover, the polyploidy defect in Mir122 knockout mice was ameliorated by adenovirus-mediated over-expression of miR-122, underscoring the critical role miR-122 plays in polyploidization. Finally, we identified direct targets of miR-122 (Cux1, Rhoa, Iqgap1, Mapre1, Nedd4l and Slc25a34) that regulate cytokinesis. Inhibition of each target induced cytokinesis failure and promoted hepatic binucleation. Conclusion: Our data demonstrate that miR-122 is both necessary and sufficient in liver polyploidization. Among the different signals that have been associated with hepatic polyploidy, miR-122 is the first liver-specific signal identified. These studies will serve as the foundation for future work investigating miR-122 in liver maturation, homeostasis and disease. Livers from C57Bl/6 mice were isolated at defined ages: embryonic day 15.5 (n=3; mixed gender), 2 weeks (n=3; male), 3 weeks (n=3, male) and 7 weeks (n=3; male). Differential miRNA expression was assessed using the nCounter Mouse miRNA Expression Assay Kit (nanoString).

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RAW246.1 cells activation by internalized synthetic miR-122

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