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ROR? directly regulates the circadian expression of clock genes and downstream targets in vivo.

ABSTRACT: In this study, we demonstrate that the lack of retinoic acid-related orphan receptor (ROR) ? or ? expression in mice significantly reduced the peak expression level of Cry1, Bmal1, E4bp4, Rev-Erb? and Per2 in an ROR isotype- and tissue-selective manner without affecting the phase of their rhythmic expression. Analysis of ROR?/ROR? double knockout mice indicated that in certain tissues ROR? and ROR? exhibited a certain degree of redundancy in regulating clock gene expression. Reporter gene analysis showed that ROR? was able to induce reporter gene activity through the RORE-containing regulatory regions of Cry1, Bmal1, Rev-Erb? and E4bp4. Co-expression of Rev-Erb? or addition of a novel ROR antagonist repressed this activation. ChIP-Seq and ChIP-Quantitative real-time polymerase chain reaction (QPCR) analysis demonstrated that in vivo ROR? regulate these genes directly and in a Zeitgeber time (ZT)-dependent manner through these ROREs. This transcriptional activation by RORs was associated with changes in histone acetylation and chromatin accessibility. The rhythmic expression of ROR?1 by clock proteins may lead to the rhythmic expression of ROR?1 target genes. The presence of ROR? binding sites and its down-regulation in ROR?-/- liver suggest that the rhythmic expression of Avpr1a depends on ROR? consistent with the concept that ROR?1 provides a link between the clock machinery and its regulation of metabolic genes.

SUBMITTER: Takeda Y

PROVIDER: S-EPMC3458568 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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RORγ directly regulates the circadian expression of clock genes and downstream targets in vivo.

Takeda Yukimasa Y Jothi Raja R Birault Veronique V Jetten Anton M AM

Nucleic acids research 20120629 17

In this study, we demonstrate that the lack of retinoic acid-related orphan receptor (ROR) γ or α expression in mice significantly reduced the peak expression level of Cry1, Bmal1, E4bp4, Rev-Erbα and Per2 in an ROR isotype- and tissue-selective manner without affecting the phase of their rhythmic expression. Analysis of RORγ/RORα double knockout mice indicated that in certain tissues RORγ and RORα exhibited a certain degree of redundancy in regulating clock gene expression. Reporter gene analys ...[more]

PMID: 22753030

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Project description:Asthma demonstrates a strong circadian rhythm with disrupted molecular clock. Melatonin which can directly regulate circadian rhythm has been reported to alleviate asthma, but whether this effect is related to its regulation on circadian clock has not yet been known. Here, female C57BL/6 mice were challenged with ovalbumin (OVA) to establish allergic airway inflammation, and were treated with melatonin or Luzindole to investigate whether the expressions of circadian clock proteins were changed in response to OVA and were affected by exogenous/endogenous melatonin. Airway inflammation, mucus secretion, protein expressions of circadian proteins (Bmal1, Per1, Clock, Timeless, Cry1 and Cry2), melatonin biosynthetase (ASMT, AANAT) and melatonin receptor (Mel-1A/B-R) were analyzed accordingly. The results showed that in the successfully established allergic airway inflammation model, inflammatory cells infiltration, expressions of circadian clock proteins in the lung tissues of OVA-challenged mice were all notably up-regulated as compared to that of the vehicle mice. Meanwhile, the protein expression of ASMT and the level of melatonin in the lung tissues were reduced in allergic mice, while the expression of melatonin receptor Mel-1A/B-R was markedly increased. After addition of exogenous melatonin, the OVA-induced airway inflammation was pronouncedly ameliorated, while simultaneously the OVA-induced expressions of Per1 and Clock were further increased. However, a melatonin receptor antagonist Luzindole further augmented the OVA-induced airway inflammation, accompanied with remarkably decreased expressions of Per1, Bmal1, Cry1 and Cry2 but notably increased expression of Timeless. Collectively, our results demonstrated that the expression of circadian clock proteins was increased in the lungs during allergic airway inflammation, and Per1 was a clock protein that can be regulated by both exogenous and endogenous melatonin, suggesting Per1 may be an important potential circadian clock target for melatonin as a negative regulatory factor against Th2-type airway inflammation.

Project description:Circadian dysfunction is a common attribute of many neurodegenerative diseases, most of which are associated with neuroinflammation. Circadian rhythm dysfunction has been associated with inflammation in the periphery, but the role of the core clock in neuroinflammation remains poorly understood. Here we demonstrate that Rev-erbα, a nuclear receptor and circadian clock component, is a mediator of microglial activation and neuroinflammation. We observed time-of-day oscillation in microglial immunoreactivity in the hippocampus, which was disrupted in Rev-erbα-/- mice. Rev-erbα deletion caused spontaneous microglial activation in the hippocampus and increased expression of proinflammatory transcripts, as well as secondary astrogliosis. Transcriptomic analysis of hippocampus from Rev-erbα-/- mice revealed a predominant inflammatory phenotype and suggested dysregulated NF-κB signaling. Primary Rev-erbα-/- microglia exhibited proinflammatory phenotypes and increased basal NF-κB activation. Chromatin immunoprecipitation revealed that Rev-erbα physically interacts with the promoter regions of several NF-κB-related genes in primary microglia. Loss of Rev-erbα in primary astrocytes had no effect on basal activation but did potentiate the inflammatory response to lipopolysaccharide (LPS). In vivo, Rev-erbα-/- mice exhibited enhanced hippocampal neuroinflammatory responses to peripheral LPS injection, while pharmacologic activation of Rev-erbs with the small molecule agonist SR9009 suppressed LPS-induced hippocampal neuroinflammation. Rev-erbα deletion influenced neuronal health, as conditioned media from Rev-erbα-deficient primary glial cultures exacerbated oxidative damage in cultured neurons. Rev-erbα-/- mice also exhibited significantly altered cortical resting-state functional connectivity, similar to that observed in neurodegenerative models. Our results reveal Rev-erbα as a pharmacologically accessible link between the circadian clock and neuroinflammation.

Dataset Information

ROR? directly regulates the circadian expression of clock genes and downstream targets in vivo.

Publications

RORγ directly regulates the circadian expression of clock genes and downstream targets in vivo.

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