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bioRxiv · 10.1101/2025.08.18.670875

Endogenous Real Time Imaging Reveals Dynamic Chromosomal Mobility During Ligand-Mediated Transcriptional Burst Events

Wang, S.·Suter, T.·Gamliel, A.·Kim, Y.·Nair, S. J.·Oh, S.·Yang, F.·Ohgi, K. A.·Wagner, T.·Gan, S.·Rosenfeld, M. G.
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Abstract

Enhancers serve as the major genomic elements regulating mammalian signal-dependent transcriptional programs, characterized by alternating periods of target gene "bursting" and "non-busting" that require investigation of induced enhancer condensates and locus motility in real time to provide dynamic insights into signal/ligand-dependent regulatory events. Here, endogenous live cell imaging has revealed the altered chromosomal dynamics/condensate formation occurring during estrogen receptor (ER)-dependent target gene bursting/post-bursting and chronic activation events. Simultaneous DNA/RNA endogenous live imaging reveals that an increased mobility of acutely ER-stimulated loci observed during the bursting phase is, unexpectedly, further increased in the subsequent non-burst phase. Single molecule tracking (SMT) of ER shows that the relatively high-burst, lower-mobility acute state was indeed enriched for high-viscosity, 1,6-hexanediol-sensative ER molecules in a low sub-diffusive confined state with enhanced condensate formation during burst activation. Consistent with this, blocking transcription with flavopiridol shifts DNA tracks into a non-confined state. Differential DNA kinetics during burst vs non-burst has provided a strategy to assess altered condensate formation during gene activation events. (165)

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Wang, S., Suter, T., Gamliel, A., Kim, Y., Nair, S. J., Oh, S., Yang, F., Ohgi, K. A., Wagner, T., Gan, S., Rosenfeld, M. G.. 2025-08-19. Endogenous Real Time Imaging Reveals Dynamic Chromosomal Mobility During Ligand-Mediated Transcriptional Burst Events. https://doi.org/10.1101/2025.08.18.670875

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