ReviewImaging Transcriptional Regulation of Eukaryotic mRNA Genes: Advances and Outlook

- Cell imaging provides a new approach to study transcriptional regulation in vivo.
- TFs, transcription sites, or single mRNAs are the imaging targets.
- Transcription bursting occurs at many eukaryotic mRNA genes and is regulated.
- Distal enhancers regulate transcription by modulating bursting kinetics.
- Molecular insights remain to be discovered by developing transcription imaging.

Regulation of eukaryotic transcription in vivo occurs at distinct stages. Previous research has identified many active or repressive transcription factors (TFs) and core transcription components and studied their functions in vitro and in vivo. Nonetheless, how individual TFs act in concert to regulate mRNA gene expression in a single cell remains poorly understood. Direct observation of TF assembly and disassembly and various biochemical reactions during transcription of a single-copy gene in vivo is the ideal approach to study this problem. Research in this area requires developing novel techniques for single-cell transcription imaging and integrating imaging studies into understanding the molecular biology of transcription. In the past decade, advanced cell imaging has enabled unprecedented capabilities to visualize individual TF molecules, to track single transcription sites, and to detect individual mRNA in fixed and living cells. These studies have raised several novel insights on transcriptional regulation such as the “hit-and-run” model and transcription bursting that could not be obtained by in vitro biochemistry analysis. At this point, the key question is how to achieve deeper understandings or discover novel mechanisms of eukaryotic transcriptional regulation by imaging transcription in single cells. Meanwhile, further technical advancements are likely required for visualizing distinct kinetic steps of transcription on a single-copy gene in vivo. This review article summarizes recent progress in the field and describes the challenges and opportunities ahead.

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