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Novel Histone Decetylase Inhibitors to Elucidate Repeat Associated Gene Silencing Mechanisms in Drosophila

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Novel Histone Decetylase Inhibitors to Elucidate Repeat Associated Gene Silencing Mechanisms in Drosophila Washington University in St. Louis Washington University Open Scholarship Washington University Spring 2017 Senior Honors Thesis Abstracts Spring 2017 Novel Histone Decetylase Inhibitors to Elucidate Repeat Associated Gene Silencing Mechanisms in Drosophila Emily Chi Washington University in St. Louis Follow this and additional works at: https://openscholarship.wustl.edu/wushta_spr2017 Recommended Citation Chi, Emily, "Novel Histone Decetylase Inhibitors to Elucidate Repeat Associated Gene Silencing Mechanisms in Drosophila" (2017). Spring 2017. 17. https://openscholarship.wustl.edu/wushta_spr2017/17 This Abstract for College of Arts & Sciences is brought to you for free and open access by the Washington University Senior Honors Thesis Abstracts at Washington University Open Scholarship. It has been accepted for inclusion in Spring 2017 by an authorized administrator of Washington University Open Scholarship. For more information, please contact [email protected]. Biology Novel Histone Deacetylase Inhibitors to Elucidate Repeat Associated Gene Silencing Mechanisms in Drosophila Emily Chi Mentors: Sarah Elgin, Elena Gracheva and Flavio Ballante Repetitious elements constitute a major portion of eukaryotic genomes. Silencing mechanisms are required to recognize and prevent their expression in cells. Silencing of repetitious elements can be achieved by formation of heterochromatin. To study this mechanism we utilized a transgenic construct containing 256 copies of a 36 bp lac Operon fragment placed upstream of an hsp70-white reporter, inserted into the Drosophila melanogaster genome. In Drosophila , expression of the white gene results in a red eye phenotype; sporadic silencing of this gene following juxtaposition with heterochromatin results in a patchy red eye phenotype referred to as Position Effect Variegation (PEV). Previous studies from the Elgin laboratory have shown that insertion of the lacO-hsp70-white transgene at the base of chromosome arm 2L results in strong silencing, sensitive to HP1 depletion, indicating heterochromatin packaging. A genetic screen suggested that the lacO-hsp70-white PEV phenotype is sensitive to mutations in genes coding for histone deacetylases (HDACs). These results led us to test several small molecule HDAC inhibitors (HDACIs), including novel HDACIs designed and synthetized by the Marshall laboratory (Biochemistry Dept, Washington University). An initial test of 12 potent human HDACIs, with diverse selectivity profiles for the ~10 HDACs present (Apicidin, Entinostat, Panobinostat, PCI-34051, SAHA, Scriptaid, Largazole, SD-L-256, Trichostatin A, Tubastatin A, T247, and Compound 4), performed on the Drosophila reporter line showed that the selected drugs did not cause any detrimental effects on fly development, with the exception of SAHA at its maximum concentration. We selected HDAC3 and HDAC6 inhibitors, compounds SD-L-256, Largazole, 6q, and 4l (Marshall lab, unpublished) for a second, more precise drug screen with optimized drug concentrations and fly population densities. Results from this screen suggest that selective inhibition of HDAC3 or HDAC6 differentially affects suppression of lacO-hsp70-white silencing. In the future, more detailed investigation is needed to fully characterize the process. 28 Spring 2017 WUSHTA.
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