Poster abstracts
Poster number 75 submitted by Blanche Chen
Natural nucleosome positioning sequences reveal induced nucleosome sliding by pioneer transcription factors.
Blanche Chen (Ohio State Biochemistry Program), Shane D. Stoeber (Department of Biochemistry and Molecular Biology, The Pennsylvania State University, State College, United States ), Hengye Chen (Department of Biochemistry and Molecular Biology, The Pennsylvania State University, State College, United States ), Lu Bai (Department of Biochemistry and Molecular Biology, The Pennsylvania State University, State College, United States ), Michael G. Poirier (Ohio State Biochemistry Program)
Abstract:
Pioneer transcription factors (pTFs) are cell-fate determinants that are highly involved in cellular reprogramming, embryonic development, and oncogenesis. Unlike canonical transcription factors (TF), whose DNA accessibility is highly hindered by nucleosomes, pTFs can intrinsically access closed chromatin and interrupt gene repression. Their pioneering activity enables them to rewire cell fates, making them a promising target for developing novel therapeutic approaches against degenerative diseases and cancer. To apply pTFs to further application, their underlying mechanism for initiating cellular reprogramming needs to be revealed. In this study, we established a library of natural nucleosome positioning sequences (NPS) from Saccharomyces cerevisiae to investigate how pTFs interact with nucleosomes and trigger the downstream cascades toward chromatin opening. In vitro nucleosome reconstitution and high-throughput sequencing were used for setting up the natural NPS library. Competitive nucleosome reconstitution was also used to measure free energy between histones and different NPS. The well-characterized NPS candidates were further applied to study nucleosome dynamics. We found that natural NPS-wrapped nucleosomes possess a higher affinity with pTFs against artificial NPS-wrapped nucleosomes. More surprisingly, our data shows that the binding of pTFs would independently induce nucleosome shifting without the existence of ATP-dependent chromatin remodelers, which is different from what was observed in the artificial NPS-wrapped nucleosomes. This work provides a set of well-characterized NPS libraries that enable us to reveal how pTFs regulate nucleosome dynamics in the cells, which will provide the foundation for applying pTFs to treatment development.
References:
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Keywords: nucleosome, transcription factor, epigenetics