Browsing by Author "Davis, Ian J."

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    Casein Kinase II Phosphorylation of Spt6 Enforces Transcriptional Fidelity by Maintaining Spn1-Spt6 Interaction
    (Elsevier, 2018-12-18) Dronamraju, Raghuvar; Kerschner, Jenny L.; Peck, Sarah A.; Hepperla, Austin J.; Adams, Alexander T.; Hughes, Katlyn D.; Aslam, Sadia; Yoblinski, Andrew R.; Davis, Ian J.; Mosley, Amber L.; Strahl, Brian D.; Biochemistry and Molecular Biology, School of Medicine
    Spt6 is a histone chaperone that associates with RNA polymerase II and deposits nucleosomes in the wake of transcription. Although Spt6 has an essential function in nucleosome deposition, it is not known whether this function is influenced by post-translational modification. Here, we report that casein kinase II (CKII) phosphorylation of Spt6 is required for nucleosome occupancy at the 5' ends of genes to prevent aberrant antisense transcription and enforce transcriptional directionality. Mechanistically, we show that CKII phosphorylation of Spt6 promotes the interaction of Spt6 with Spn1, a binding partner required for chromatin reassembly and full recruitment of Spt6 to genes. Our study defines a function for CKII phosphorylation in transcription and highlights the importance of post-translational modification in histone chaperone function.
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    MS0621, a novel small-molecule modulator of Ewing sarcoma chromatin accessibility, interacts with an RNA-associated macromolecular complex and influences RNA splicing
    (Frontiers Media, 2023-01-30) Vital, Tamara; Wali, Aminah; Butler, Kyle V.; Xiong, Yan; Foster, Joseph P., II; Marcel, Shelsa S.; McFadden, Andrew W.; Nguyen, Valerie U.; Bailey, Benton M.; Lamb, Kelsey N.; James, Lindsey I.; Frye, Stephen V.; Mosely, Amber L.; Jin, Jian; Pattenden, Samantha G.; Davis, Ian J.; Biochemistry and Molecular Biology, School of Medicine
    Ewing sarcoma is a cancer of children and young adults characterized by the critical translocation-associated fusion oncoprotein EWSR1::FLI1. EWSR1::FLI1 targets characteristic genetic loci where it mediates aberrant chromatin and the establishment of de novo enhancers. Ewing sarcoma thus provides a model to interrogate mechanisms underlying chromatin dysregulation in tumorigenesis. Previously, we developed a high-throughput chromatin-based screening platform based on the de novo enhancers and demonstrated its utility in identifying small molecules capable of altering chromatin accessibility. Here, we report the identification of MS0621, a molecule with previously uncharacterized mechanism of action, as a small molecule modulator of chromatin state at sites of aberrant chromatin accessibility at EWSR1::FLI1-bound loci. MS0621 suppresses cellular proliferation of Ewing sarcoma cell lines by cell cycle arrest. Proteomic studies demonstrate that MS0621 associates with EWSR1::FLI1, RNA binding and splicing proteins, as well as chromatin regulatory proteins. Surprisingly, interactions with chromatin and many RNA-binding proteins, including EWSR1::FLI1 and its known interactors, were RNA-independent. Our findings suggest that MS0621 affects EWSR1::FLI1-mediated chromatin activity by interacting with and altering the activity of RNA splicing machinery and chromatin modulating factors. Genetic modulation of these proteins similarly inhibits proliferation and alters chromatin in Ewing sarcoma cells. The use of an oncogene-associated chromatin signature as a target allows for a direct approach to screen for unrecognized modulators of epigenetic machinery and provides a framework for using chromatin-based assays for future therapeutic discovery efforts.
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    A Role for Widely Interspaced Zinc Finger (WIZ) in Retention of the G9a Methyltransferase on Chromatin*.
    (ASBMB, 2015-10-23) Simon, Jeremy M.; Parker, Joel S.; Liu, Feng; Rothbart, Scott B.; Ait-Si-Ali, Slimane; Strahl, Brian D.; Jin, Jian; Davis, Ian J.; Mosley, Amber L.; Pattenden, Samantha G.; Department of Biochemistry and Molecular Biology, IU School of Medicine
    Background: G9a-GLP lysine methyltransferases mono- and di-methylate histone H3 lysine 9 (H3K9me2).Results: Widely interspaced zinc finger (WIZ) regulates H3K9me2 levels through a mechanism that involves retention of G9a on chromatin.Conclusion: The G9a-GLP-WIZ complex has unique functions when bound to chromatin that are independent of the H3K9me2 mark.Significance: Combining pharmacologic and genetic manipulations is essential to any translational hypotheses related to G9a function.