Real-Time Dynamics of RNA Polymerase II Clustering in Live Human Cells
Ibrahim I. Cisse, Ignacio Izeddin, Sebastien Z. Causse, Lydia Boudarene, Adrien Senecal, Leila Muresan, Claire Dugast- Darzacq, Bassam Hajj, Maxime Dahan, Xavier Darzacq
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, refuting their notion as 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 cells 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.
DOI : 10.1126/science.1239053
