The SAGA complex is a highly conserved transcriptional co-activator comprised of over 20 protein subunits. SAGA contains 2 enzymatic activities, a histone acetyltransferase and a histone deubiquitinase, interacts with sequence-specific DNA binding transcription factors, and facilitates the formation of preinitiation transcription complexes. SAGA is linked to the functions of several oncogene and tumor suppressor gene products, and disruption and/or misexpression of SAGA subunits is observed in many forms of cancer and can give rise to neurodegenerative disease. While SAGA was discovered and most widely studied in yeast, it is not essential in that organism. By contrast, SAGA is essential for the development of multicellular eukaryotes, yet very little is known about its functions in developmental programs of gene expression. This application proposes to combine genetic and tissue-specific tools in the model organism, Drosophila melanogaster, with powerful proteomic and genomic approaches to dissect the functions of SAGA in cell-type and tissue-specific gene expression. The first specific aim will complete the functional and phenotypical analysis of recently identified but as yet uncharacterized Drosophila SAGA subunits. These include the fly homolog of the human ATXN7 protein, which when perturbed gives rise to spinocerebellar ataxia 7, and two splicing proteins that may link SAGA to RNA splicing. In the second aim, we propose to express epitope tagged versions of SAGA subunits in specific tissues and determine the target genes of SAGA in each tissue using chromatin immunoprecipitation and high throughput sequencing. The dependence of expression on each of the SAGA target genes on each of the SAGA activities (acetyltransferase, deubiquitinase, coactivator) will be measured in the appropriate SAGA mutant embryos. Lastly, we have identified a number of tissue-specific transcription factors that co-purify with SAGA. These transcription factors will be examined for their roles in recruiting SAGA to their respective target genes. Thus, this project will establish a comprehensive view of SAGA localization and function in specific tissues in a developing multicellular eukaryote. We anticipate that analysis of the mechanisms by which SAGA regulates tissue-specific gene expression will establish paradigms for SAGA function in metazoans, and advance our understanding of its roles in cancer and neurodegenerative disease.

Public Health Relevance

The SAGA protein complex is disrupted or misregulated in several cancers and in neurodegenerative disease. This project seeks to elucidate the normal functions of the SAGA complex in the development of multi-cellular organisms using fruit flies as a model system to gain insights into how its perturbation contributes to human disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM099945-03
Application #
8655170
Study Section
Molecular Genetics B Study Section (MGB)
Program Officer
Sledjeski, Darren D
Project Start
2012-05-01
Project End
2016-04-30
Budget Start
2014-05-01
Budget End
2015-04-30
Support Year
3
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Stowers Institute for Medical Research
Department
Type
DUNS #
City
Kansas City
State
MO
Country
United States
Zip Code
64110
Li, Xuanying; Seidel, Christopher W; Szerszen, Leanne T et al. (2017) Enzymatic modules of the SAGA chromatin-modifying complex play distinct roles in Drosophila gene expression and development. Genes Dev 31:1588-1600
Dyer, Jamie O; Dutta, Arnob; Gogol, Madelaine et al. (2017) Myeloid Leukemia Factor Acts in a Chaperone Complex to Regulate Transcription Factor Stability and Gene Expression. J Mol Biol 429:2093-2107
Huang, Fu; Abmayr, Susan M; Workman, Jerry L (2016) Regulation of KAT6 Acetyltransferases and Their Roles in Cell Cycle Progression, Stem Cell Maintenance, and Human Disease. Mol Cell Biol 36:1900-7
Huang, Fu; Saraf, Anita; Florens, Laurence et al. (2016) The Enok acetyltransferase complex interacts with Elg1 and negatively regulates PCNA unloading to promote the G1/S transition. Genes Dev 30:1198-210
Workman, Jerry L (2016) CHROMATIN. It takes teamwork to modify chromatin. Science 351:667
Lei, Kai; Thi-Kim Vu, Hanh; Mohan, Ryan D et al. (2016) Egf Signaling Directs Neoblast Repopulation by Regulating Asymmetric Cell Division in Planarians. Dev Cell 38:413-29
Li, Wenqian; Atanassov, Boyko S; Lan, Xianjiang et al. (2016) Cytoplasmic ATXN7L3B Interferes with Nuclear Functions of the SAGA Deubiquitinase Module. Mol Cell Biol 36:2855-2866
Atanassov, Boyko S; Mohan, Ryan D; Lan, Xianjiang et al. (2016) ATXN7L3 and ENY2 Coordinate Activity of Multiple H2B Deubiquitinases Important for Cellular Proliferation and Tumor Growth. Mol Cell 62:558-71
Lan, Xianjiang; Atanassov, Boyko S; Li, Wenqian et al. (2016) USP44 Is an Integral Component of N-CoR that Contributes to Gene Repression by Deubiquitinating Histone H2B. Cell Rep 17:2382-2393
Stegeman, Rachel; Spreacker, Peyton J; Swanson, Selene K et al. (2016) The Spliceosomal Protein SF3B5 is a Novel Component of Drosophila SAGA that Functions in Gene Expression Independent of Splicing. J Mol Biol 428:3632-49

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