Direct regulation of CLOCK expression by REV-ERB

Area of Science:

• Molecular Biology
• Chronobiology
• Gene Regulation

Background:

• Circadian rhythms rely on transcriptional feedback loops involving proteins like CLOCK, BMAL1, PERIOD (PER), and CRYPTOCHROME (CRY).
• The nuclear receptor REV-ERBα is known to regulate BMAL1 expression, a key component of the circadian machinery.

Purpose of the Study:

• To investigate whether REV-ERBα also regulates the expression of CLOCK, another heterodimer partner of BMAL1.
• To elucidate the role of REV-ERBα in the regulation of the BMAL1/CLOCK heterodimer activity.

Main Methods:

• Chromatin immunoprecipitation-microarray (ChIP-array) screen to identify REV-ERBα binding sites in the CLOCK gene.
• Analysis of CLOCK mRNA expression following suppression of REV-ERBα.
• Identification and functional analysis of a REV-ERB response element (RevRE) in the CLOCK gene.

Main Results:

• A REV-ERBα binding site was identified in the first intron of the CLOCK gene.
• Suppression of REV-ERBα led to increased CLOCK mRNA levels, indicating transcriptional repression.
• A conserved RevRE in the CLOCK gene conferred REV-ERB responsiveness to a reporter gene.

Conclusions:

• REV-ERBα directly regulates CLOCK gene expression, acting as a transcriptional repressor.
• REV-ERBα plays a dual role in regulating the BMAL1/CLOCK heterodimer by controlling the expression of both CLOCK and BMAL1 genes.
• This finding deepens the understanding of circadian rhythm regulation at the molecular level.