The broad goals of this research are to understand the mechanisms that promote stable, mitotically heritable states of gene expression during development. They continue to focus on characterizing the mutually antagonistic chromatin-directed activities of Drosophila Polycomb Group and Trithorax Group proteins that promote and maintain the distinct chromatin states associated with transcriptionally silent and active genes respectively. Their activities are implicated in many biological processes, including cell fate determination, stem cell maintenance and differentiation, regeneration, and others. They are implicated in human diseases, notably various cancers. The proposed experiments build on discoveries made in the previous funding period.
Aim 1 is to investigate a newly discovered inhibitory activity of the Polycomb (PC) protein, a PRC1 subunit, on the catalytic activity of the CBP acetyltransferase, a global transcriptional co-activator. We will use CRISPR genome editing to create PC mutant proteins that fail to bind CBP in vitro and in vivo. We will characterize their effects in vivo on expression of both silent and active Polycomb-regulated genes, as well as on their genome- wide distribution.
Aim 2 is to investigate the effects of newly discovered acetylation of PC on its in vivo function using CRISPR genome editing and transgenic lines that express PC containing substitutions of acetylated lysines with glutamines (acetyl-K mimic) and arginines (charge conservative but unacetylatable).
Aim 3 is to investigate the interplay of the chromatin-directed activities of TRX methyltransferase and CBP acetyltransferase, extending our observation that the histone H3K4me1 product of TRX stimulates its subsequent acetylation of H3K27 by CBP, which directly blocks repressive H3K27 methylation by PRC2. We will determine if binding of CBP to TRX is required for this effect in vivo by mutating the CBP-binding region of TRX. This work will provide new insights into the regulation of active and silent chromatin states during development. .

Public Health Relevance

This proposal focuses on understanding basic mechanisms underlying the epigenetic regulation of gene expression by the Polycomb Group (PcG) and Trithorax Group (TrxG) proteins, which act antagonistically to each other to maintain, respectively, transcriptionally silent and active chromatin states. PcG and TrxG proteins regulate thousands of genes and are involved in a large number of biological processes, including genome- wide changes in transcription programs that accompany cell determination, differentiation and regeneration. Perturbations of their functioning and the resulting disturbances in chromatin states and gene expression are implicated in an increasing number of disease states, including various cancers, developmental disorders, and others. The research outlined in this proposal will lead to a deeper understanding of the fundamental mechanisms underlying the epigenetic regulation of gene expression, and will have broad implications for understanding cancer, developmental disorders, and other diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM039255-26A1
Application #
9740380
Study Section
Development - 2 Study Section (DEV2)
Program Officer
Carter, Anthony D
Project Start
1988-04-01
Project End
2021-08-31
Budget Start
2019-09-01
Budget End
2020-08-31
Support Year
26
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Case Western Reserve University
Department
Genetics
Type
Schools of Medicine
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106
Tie, Feng; Banerjee, Rakhee; Fu, Chen et al. (2016) Polycomb inhibits histone acetylation by CBP by binding directly to its catalytic domain. Proc Natl Acad Sci U S A 113:E744-53
Du, Juan; Zhang, Junzheng; He, Tao et al. (2016) Stuxnet Facilitates the Degradation of Polycomb Protein during Development. Dev Cell 37:507-19
Tie, Feng; Banerjee, Rakhee; Saiakhova, Alina R et al. (2014) Trithorax monomethylates histone H3K4 and interacts directly with CBP to promote H3K27 acetylation and antagonize Polycomb silencing. Development 141:1129-39
Mason-Suares, Heather; Tie, Feng; Yan, Christopher M et al. (2013) Polycomb silencing of the Drosophila 4E-BP gene regulates imaginal disc cell growth. Dev Biol 380:111-24
Tie, Feng; Banerjee, Rakhee; Conrad, Patricia A et al. (2012) Histone demethylase UTX and chromatin remodeler BRM bind directly to CBP and modulate acetylation of histone H3 lysine 27. Mol Cell Biol 32:2323-34
Stepanik, Vincent A; Harte, Peter J (2012) A mutation in the E(Z) methyltransferase that increases trimethylation of histone H3 lysine 27 and causes inappropriate silencing of active Polycomb target genes. Dev Biol 364:249-58
Tie, Feng; Banerjee, Rakhee; Stratton, Carl A et al. (2009) CBP-mediated acetylation of histone H3 lysine 27 antagonizes Drosophila Polycomb silencing. Development 136:3131-41
Kurzhals, Rebeccah L; Tie, Feng; Stratton, Carl A et al. (2008) Drosophila ESC-like can substitute for ESC and becomes required for Polycomb silencing if ESC is absent. Dev Biol 313:293-306
Tie, Feng; Stratton, Carl A; Kurzhals, Rebeccah L et al. (2007) The N terminus of Drosophila ESC binds directly to histone H3 and is required for E(Z)-dependent trimethylation of H3 lysine 27. Mol Cell Biol 27:2014-26
Tie, Feng; Siebold, Alex P; Harte, Peter J (2005) The N-terminus of Drosophila ESC mediates its phosphorylation and dimerization. Biochem Biophys Res Commun 332:622-32

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