Rev-Erbs repress macrophage gene expression by inhibiting enhancer-directed transcription

Area of Science:

• Molecular Biology
• Gene Regulation
• Epigenetics

Background:

• Rev-Erb nuclear receptors (Rev-Erb-α and Rev-Erb-β) are known regulators of circadian rhythm, metabolism, and inflammation.
• Rev-Erbs function as transcriptional repressors by recruiting co-repressor complexes to target gene regulatory elements.
• The molecular mechanisms underlying cell-specific repression by Rev-Erbs remain unclear.

Purpose of the Study:

• To investigate the role of Rev-Erbs in macrophage-specific gene expression programs.
• To elucidate the mechanism by which Rev-Erbs mediate transcriptional repression.
• To determine the functional significance of enhancer-derived RNAs (eRNAs) in gene regulation.

Main Methods:

• Utilized mouse macrophages as a model system.
• Employed a modified global run-on sequencing technique to precisely map nascent 5' ends of eRNAs.
• Performed targeted degradation of eRNAs to assess their functional impact on gene expression.

Main Results:

• Rev-Erbs inhibit the function of distal enhancers selected by macrophage-lineage factors, establishing macrophage-specific repression.
• Rev-Erb-mediated repression is linked to the inhibition of enhancer-derived RNA (eRNA) transcription.
• Targeted degradation of eRNAs reduced the expression of nearby messenger RNAs, indicating a direct role for eRNAs in enhancer function.
• Enhancer activity transfer to promoters requires both transcription factor binding sites and specific eRNA encoding sequences.

Conclusions:

• Rev-Erbs suppress gene expression by inhibiting eRNA transcription at distal enhancers.
• eRNAs play a direct role in enhancer function and gene regulation.
• These findings reveal a novel mechanism for cell-specific gene repression mediated by Rev-Erbs and eRNAs.