Abstract

The roles of Rev-erbα and circadian clock in colonic inflammation remain unclarified. Here we show colon clock genes (including Rev-erbα) are dysregulated in mice with DSS-induced colitis. In turn, disruption of the circadian clock exacerbates experimental colitis. Rev-erbα-deficient mice are more sensitive to DSS-induced colitis, supporting a critical role of Rev-erbα in disease development. Further, Rev-erbα ablation causes activation of Nlrp3 inflammasome in mice. Cell-based experiments reveal Rev-erbα inactivates Nlrp3 inflammasome mainly at the priming stage. Rev-erbα directly represses Nlrp3 transcription through specific binding to the promoter region. Additionally, Rev-erbα represses p65 transcription and indirectly repressed Nlrp3 via the NF-κB pathway. Interestingly, Rev-erbα activation in wild-type mice by SR9009 attenuates DSS-induced colitis, whereas the protective effects are lost in Nlrp3−/− and Rev-erbα−/− mice. Taken together, Rev-erbα regulates experimental colitis through its repressive action on the NF-κB/Nlrp3 axis. Targeting Rev-erbα may represent a promising approach for prevention and management of colitis.

Highlights

  • The roles of Rev-erbα and circadian clock in colonic inflammation remain unclarified

  • NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a central role in innate immune responses to pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs)[25,26,27]

  • We examined the effects of Bmal[1] knockout on colitis development

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Summary

Introduction

The roles of Rev-erbα and circadian clock in colonic inflammation remain unclarified. We show colon clock genes (including Rev-erbα) are dysregulated in mice with DSS-induced colitis. Rev-erbα ablation causes activation of Nlrp[3] inflammasome in mice. CLOCK and BMAL1 function as a heterodimer that activates transcription of clock-controlled genes, including PER and CRY. Once reaching a threshold level, PER and CRY proteins inhibit the activity of CLOCK/BMAL1, thereby repressing their own expressions. This type of transcriptional–translational feedback loop system generates circadian oscillations of clock-controlled genes[6]. REV-ERBα repression of BMAL1 is an accessory feedback loop that consolidates the rhythms of circadian oscillators[8]. Activation of NLRP3 inflammasome promotes the cleavage of caspase-1 and maturation and secretion of proinflammatory cytokines IL-1β and IL-1828

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