The aim of this research is to understand how stable states of gene expression are maintained during development. Molecular, genetic and biochemical methods will be used to study chromatin proteins that control transcription of homeotic (Hox) genes in Drosophila melanogaster. Hox genes determine fly segment identities and their selective expression is needed throughout development. Segmentation gene products control initial patterns of Hox expression in 2-hour-old embryos, but they decay by about 4 hours. The Polycomb group (PcG) proteins are transcriptional repressors that then maintain Hox expression patterns during the rest of development. Current models suggest repression is maintained through covalent histone modification and stable association of PcG protein complexes in the local chromatin. This research will investigate molecular roles of PcG complexes and their subunits. Two biochemically separable PcG complexes have been purified; the ESC-E(Z) complex contains the PcG proteins Extra sex combs (ESC), Enhancer of zeste [E(Z)] and Suppressor of zeste-12 [SU(Z)12]. This complex has an enzyme activity that methylates histones. The other complex, called PRC1, contains Polycomb (PC), Polyhomeotic (PH), Posterior sex combs (PSC) and Sex comb extra (SCE). This work will address mechanisms that regulate the ESC-E(Z) complex and define roles of individual subunits. Another goal is to determine if and how the Sex comb on midleg (SCM) repressor works with PRCI. Additional studies will track PcG chromatin states during the cell cycle. The methods used will include protein purification, enzyme assays, site-directed mutagenesis, chromatin analyses, loss-of-function studies, transgene manipulating, protein interaction tests, and immunostaining of chromosomes. Every fly PcG repressor has homologs in mammals. These are functional homologs since PcG knockouts produce Hox defects in mouse embryos that parallel defects in fly PcG mutants. Human PcG complexes resemble their fly counterparts in composition and activity. Thus, determination of PcG mechanisms in flies should yield insight about developmental controls in higher organisms. PcG repressors are implicated in lymphomagenesis and in normal hematopoiesis. The human homolog of E(Z) is implicated in disease progression of breast and prostate cancers. Knowledge about PcG mechanisms in flies may thus improve understanding of normal blood cell development and processes that underlie these human cancers.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM049850-11
Application #
7105051
Study Section
Genetics Study Section (GEN)
Program Officer
Carter, Anthony D
Project Start
1996-08-01
Project End
2008-07-31
Budget Start
2006-08-01
Budget End
2007-07-31
Support Year
11
Fiscal Year
2006
Total Cost
$287,910
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Genetics
Type
Schools of Medicine
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Wang, Liangjun; Joshi, Preeti; Miller, Ellen L et al. (2018) A Role for Monomethylation of Histone H3-K27 in Gene Activity in Drosophila. Genetics 208:1023-1036
Herzog, Veronika A; Lempradl, Adelheid; Trupke, Johanna et al. (2014) A strand-specific switch in noncoding transcription switches the function of a Polycomb/Trithorax response element. Nat Genet 46:973-981
Simon, Jeffrey A; Kingston, Robert E (2013) Occupying chromatin: Polycomb mechanisms for getting to genomic targets, stopping transcriptional traffic, and staying put. Mol Cell 49:808-24
Rai, Aswathy N; Vargas, Marcus L; Wang, Liangjun et al. (2013) Elements of the polycomb repressor SU(Z)12 needed for histone H3-K27 methylation, the interface with E(Z), and in vivo function. Mol Cell Biol 33:4844-56
O'Meara, M Maggie; Simon, Jeffrey A (2012) Inner workings and regulatory inputs that control Polycomb repressive complex 2. Chromosoma 121:221-34
Smith, Matthew; Mallin, Daniel R; Simon, Jeffrey A et al. (2011) Small ubiquitin-like modifier (SUMO) conjugation impedes transcriptional silencing by the polycomb group repressor Sex Comb on Midleg. J Biol Chem 286:11391-400
Wang, Liangjun; Jahren, Neal; Miller, Ellen L et al. (2010) Comparative analysis of chromatin binding by Sex Comb on Midleg (SCM) and other polycomb group repressors at a Drosophila Hox gene. Mol Cell Biol 30:2584-93
Chen, Shuai; Bohrer, Laura R; Rai, Aswathy N et al. (2010) Cyclin-dependent kinases regulate epigenetic gene silencing through phosphorylation of EZH2. Nat Cell Biol 12:1108-14
Zhu, Changqi C; Bornemann, Douglas J; Zhitomirsky, David et al. (2008) Drosophila histone deacetylase-3 controls imaginal disc size through suppression of apoptosis. PLoS Genet 4:e1000009
Wang, Liangjun; Jahren, Neal; Vargas, Marcus L et al. (2006) Alternative ESC and ESC-like subunits of a polycomb group histone methyltransferase complex are differentially deployed during Drosophila development. Mol Cell Biol 26:2637-47

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