Live-cell imaging reveals enhancer-dependent <i>Sox2</i> transcription in the absence of enhancer proximity.

Abstract

Enhancers are important regulatory elements that can control gene activity across vast genetic distances. However, the underlying nature of this regulation remains obscured because it has been difficult to observe in living cells. Here, we visualize the spatial organization and transcriptional output of the key pluripotency regulator <i>Sox2</i> and its essential enhancer <i>Sox2</i> Control Region (SCR) in living embryonic stem cells (ESCs). We find that <i>Sox2</i> and SCR show no evidence of enhanced spatial proximity and that spatial dynamics of this pair is limited over tens of minutes. <i>Sox2</i> transcription occurs in short, intermittent bursts in ESCs and, intriguingly, we find this activity demonstrates no association with enhancer proximity, suggesting that direct enhancer-promoter contacts do not drive contemporaneous <i>Sox2</i> transcription. Our study establishes a framework for interrogation of enhancer function in living cells and supports an unexpected mechanism for enhancer control of <i>Sox2</i> expression that uncouples transcription from enhancer proximity.