Article: article from journal or magazin.
Integration of microRNA miR-122 in hepatic circadian gene expression.
Genes and Development
In liver, most metabolic pathways are under circadian control, and hundreds of protein-encoding genes are thus transcribed in a cyclic fashion. Here we show that rhythmic transcription extends to the locus specifying miR-122, a highly abundant, hepatocyte-specific microRNA. Genetic loss-of-function and gain-of-function experiments have identified the orphan nuclear receptor REV-ERBalpha as the major circadian regulator of mir-122 transcription. Although due to its long half-life mature miR-122 accumulates at nearly constant rates throughout the day, this miRNA is tightly associated with control mechanisms governing circadian gene expression. Thus, the knockdown of miR-122 expression via an antisense oligonucleotide (ASO) strategy resulted in the up- and down-regulation of hundreds of mRNAs, of which a disproportionately high fraction accumulates in a circadian fashion. miR-122 has previously been linked to the regulation of cholesterol and lipid metabolism. The transcripts associated with these pathways indeed show the strongest time point-specific changes upon miR-122 depletion. The identification of Pparbeta/delta and the peroxisome proliferator-activated receptor alpha (PPARalpha) coactivator Smarcd1/Baf60a as novel miR-122 targets suggests an involvement of the circadian metabolic regulators of the PPAR family in miR-122-mediated metabolic control.
Animals, Circadian Rhythm/genetics, Circadian Rhythm/physiology, DNA-Binding Proteins/metabolism, Gene Expression Profiling, Gene Expression Regulation, Genome/genetics, Liver/metabolism, Male, Mice, Mice, Inbred C57BL, MicroRNAs/metabolism, Nuclear Receptor Subfamily 1, Group D, Member 1, Oligonucleotide Array Sequence Analysis, Peroxisome Proliferator-Activated Receptors/metabolism, RNA, Messenger/metabolism, Receptors, Cytoplasmic and Nuclear/metabolism, Time Factors
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