A novel E4BP4 element drives circadian expression of mPeriod2

Abstract

Period2 (Per2) is an essential component of the mammalian clock mechanism and robust circadian expression of Per2 is essential for the maintenance of circadian rhythms. Although recent studies have shown that the circadian E2 enhancer (a non-canonical E-box) accounts for most of the circadian transcriptional drive of mPer2, little is known about the other cis-elements of mPer2 oscillatory transcription. Here, we examined the contribution of E4BP4 to Per2 mRNA oscillation in the cell-autonomous clock. Knockdown experiments of E4BP4 in both Northern blots and real-time luciferase assays suggested that endogenous E4BP4 negatively regulates Per2 mRNA oscillation. Sequence analysis revealed two putative E4BP4-binding sites (termed A-site and B-site) on mammalian Per2 promoter regions. Luciferase assays with mutant constructs showed that a novel E4BP4-binding site (B-site) is responsible for E4BP4-mediated transcriptional repression of Per2. Furthermore, chromatin immunoprecipitation assays in vivo showed that the peak of E4BP4 binding to the B-site on the Per2 promoter almost matched the trough of Per2 mRNA expression. Importantly, real-time luciferase assays showed that the B-site in addition to the E2 enhancer is required for robust circadian expression of Per2 in the cell-autonomous clock. These findings indicated that E4BP4 is required for the negative regulation of mammalian circadian clocks.

β-adrenergic receptor signaling regulates Ptgs2 by driving circadian gene expression in osteoblasts

“…This feedback loop might involve a set of clock genes that are regulated by the Bmal1-Clock heterodimer in MC3T3-E1 osteoblastic cells. Previous reports have shown that Per2 genes have a cyclic AMP response element as well as D-and E-box-binding elements in their promoter (Yoo et al, 2005;Yagita and Okamura, 2000;Ohno et al, 2007). In the present study, acute Iso treatment increased Per2 expression in MC3T3-E1 cells (Fig.…”

Redundant Function of REV-ERBα and β and Non-essential Role for BMAL1 Cycling in Transcriptional Regulation of Intracellular Circadian Rhythms

“…These secondary loops are directly regulated by the core loop through the E-boxes [31]. E4BP4 and DBP, analogs of dVRI and dPDP1 in flies [16], form an oscillatory loop by feeding back to regulate Per2 transcription [31,[38][39][40]. DEC1 and DEC2 form another feedback loop, functioning to repress E-box-mediated transcription [41].…”

Real-Time Analysis of the Circadian Oscillation of the Rev-Erb ^|^beta; Promoter

“…6). Previous studies have shown that the E'-box and D-box structure of Per2 gene is very similar to Rev-Erbβ gene, which may be one of the reasons why the phase of Rev-Erbβ gene oscillation looks similar to that of Per2 gene 28) .…”