2/10 – Jan-Hendrik Spille, University of Illinois at Chicago

Speaker: Jan-Hendrik Spille

Visiting Research Assistant Professor, Department of Physics, UIC

Title: Quantitative Imaging of Transcription Organization in Live Cells

Abstract: Models of gene expression regulation have emerged from genetic and biochemical studies with limited insight into the spatial organization and temporal dynamics in living cells. Super resolution and lattice light sheet imaging of endogenous RNA Polymerase II (Pol II) and Mediator helped us reveal the organization of these key factors in transient clusters that modulate transcriptional output of the beta actin gene. In mouse embryonic stem cells, Pol II and Mediator form stable, yet dynamically organized entities at large or clustered enhancer elements with properties of biomolecular condensates. Condensates are transcriptional hot spots and sensitive to transcription inhibitors. Our results indicate a hierarchical organization of condensates in which Mediator assumes the role of a scaffold protein and phosphorylation of the C-terminal domain controls partitioning of Pol II as a client into Mediator condensates or nuclear speckles. I will highlight how quantitative imaging will help us resolve open questions and discuss our current understanding of transcription condensate organization and function, as well as implications for the organization of the cell nucleus.