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Updated: May 10, 2026

Measuring the Kinetics of mRNA Transcription in Single Living Cells
Published on: August 25, 2011
Real-time dynamics of RNA polymerase II clustering in live human cells
Ibrahim I Cisse1, Ignacio Izeddin, Sebastien Z Causse
1Functional Imaging of Transcription, CNRS UMR8197, Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, Paris, 75005 France.
Abstract:
Transcription is reported to be spatially compartmentalized in nuclear transcription factories with clusters of RNA polymerase II (Pol II). However, little is known about when these foci assemble or their relative stability. We developed a quantitative single-cell approach to characterize protein spatiotemporal organization, with single-molecule sensitivity in live eukaryotic cells. We observed that Pol II clusters form transiently, with an average lifetime of 5.1 (± 0.4) seconds, which refutes the notion that they are statically assembled substructures. Stimuli affecting transcription yielded orders-of-magnitude changes in the dynamics of Pol II clusters, which implies that clustering is regulated and plays a role in the cell's ability to effect rapid response to external signals. Our results suggest that transient crowding of enzymes may aid in rate-limiting steps of gene regulation.
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