Seminar - Nir Friedman

photo of Dr. Nir Friedman
March 19, 2018 - 12:00pm
Location: 
601 Fairchild

The Hebrew University of Jerusalem

Host: Guy Sella

Title: “Transient Depletion and Recovery of the Essential RSC Chromatin Remodeling Complex Highlights its Role in Transcriptional Regulation”

Abstract: The organization of chromatin plays a key role in regulation of transcriptional processes. Extensive research studied the nucleosome organization along the genome and how it relates to transcription. Yet, we do not understand how this organization is established and maintained. Here, we use an induced degron system to study how rapid clearance of ATP-dependent chromatin remodelers affect nucleosome locations. We find that depletion of Sth1, the catalytic subunit of the RSC complex, leads to rapid fill-in of nucleosome-free regions at gene promoters. These changes are reversible upon reintroduction of RSC, and do not depend on major chromatin reassembly during DNA replication. Using combination of nucleosome positioning assays and RNA-seq approaches we dissect the interaction between transcription and RSC-dependent nucleosome positioning. We find that RSC buffers the connection between transcription and promoter occupancy, and is crucial in maintaining open promoters of low expressed genes. Moreover, RSC is not directly required for an acute transcriptional response. We find that changes in nucleosome positions are tightly related to the specific TSS usage at promoters. Finally we suggest organizational principles that determine nucleosome positions with and without RSC and how these interact with the transcriptional process.

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