Molecular Biology

Liverish Days and Nights

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Science  03 Jul 2009:
Vol. 325, Issue 5936, pp. 12
DOI: 10.1126/science.325_12c

Biological processes with circadian rhythms show periodicity that correlates with the day/night cycle, and many metabolic pathways display such a regulatory mechanism. Prior work has suggested that between 2 and 10% of the liver transcriptome is under circadian control. Gatfield et al. show that miR-122, an abundant hepatocyte microRNA, is under circadian control. The abundance of the miR-122 precursor varies 4- to 10-fold during the day. However, accumulation is constant in the liver of mice lacking the orphan nuclear receptor REV-ERBα. When miR-122 is knocked down, hundreds of mRNAs are expressed. Peroxisome proliferation–activated receptor (PPAR) β/δ and the coactivator SMARCD1/BAF60a, two known metabolism regulators, are specific miR-122 targets, linking circadian rhythms with the PPAR family of nuclear receptors and liver metabolism.

Genes Dev. 23, 1313 (2009).

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