The orphan receptor Rev-erbα gene is a target of the circadian clock pacemaker

Abstract

Rev-erb is a ubiquitously expressed orphan nuclear receptor which functions as a constitutive transcriptional repressor and is expressed in vertebrates according to a robust circadian rhythm. We report here that two Rev-erb mRNA isoforms, namely Rev-erb 1 and Rev-erb 2, are generated through alternative promoter usage and that both show a circadian expression pattern in an in vitro system using serum-shocked fibroblasts. Both promoter regions P1 (Rev-erb 1) and P2 (Rev-erb 2) contain several E-box DNA sequences which function as response elements for the core circadian-clock components: CLOCK and BMAL1. The CLOCK-BMAL1 heterodimer stimulates the activity of both P1 and P2 promoters in transient transfection assay by 3-6-fold. This activation was inhibited by the overexpression of CRY1, a component of the negative limb of the circadian transcriptional loop. Critical E-box elements were mapped within both promoters. This regulation is conserved in vertebrates since we found that the CLOCK-BMAL1 heterodimer also regulates the zebrafish Rev-erb gene. In line with these data Rev-erb circadian expression was strongly impaired in the livers of Clock mutant mice and in the pineal glands of zebrafish embryos treated with Clock and Bmal1 antisense oligonucleotides. Together these data demonstrate that CLOCK is a critical regulator of Rev-erb circadian gene expression in evolutionarily distant vertebrates and suggest a role for Rev-erb in the circadian clock output.

A circadian clock in hippocampus is regulated by interaction between oligophrenin-1 and Rev-erbα

“…In Drosophila, levels of key synaptic proteins α-DLG, synapsin, and syntaxin have been related to behavioral states correlated with the sleep-wake cycle. 36 Rev-erbα transcription is rhythmic because it is enhanced by Clock-Bmal1, and repressed by PerCry 37,38 and Rev-erbα protein 21 . Rev-erbα also represses Bmal1 transcription 17 .…”

Involvement of circadian clock gene Clock in diabetes‐induced circadian augmentation of plasminogen activator inhibitor‐1 (PAI‐1) expression in the mouse heart

“…CLOCK forms heterodimers with BMAL1 (a bHLH-PAS transcription factor) and transactivates other clock genes such as period1 (Per1), Per2, cryptochrome1 (Cry1), and Cry2 via E-box elements in their promoters [6,7]. Circadian output genes such as albumin D-site binding protein (DBP) [8,9], prokineticin 2 [10], Wee1 [11,12], peroxisome proliferator-activated receptor a (PPARa) [13], and Rev-erba [14] also have E-box elements in their flanking regions, and the rhythmic expression of these genes is CLOCKdependent in mammals. Therefore, whether the circadian expression of PAI-1 mRNA is actually reduced in Clock mutant mice in the same manner as that of the mPer genes, DBP, and PPARa, should be of wide interest.…”

Novel functions for Period 3 and Exo-rhodopsin in rhythmic transcription and melatonin biosynthesis within the zebrafish pineal organ

“…For instance, functional Clock/BMAL sites within the aanat2 promoter are found within a 257 bp Pineal Restrictive Downstream Module (PRDM) that contains three Otx binding sites and two Clock/BMAL binding sites [1,2]. Similarly, the promoter for the Otx5 target gene reverb-alpha contains a 165 bp region upstream of the translation start site that contains two Clock/BMAL binding sites that are essential for Clock/ BMAL mediated transcription in COS-1 cells [56]. One possibility is that there are additional Clock/BMAL sites further upstream or downstream of the coding sequence or non-canonical binding sites that we do not recognize.…”