Steroid hormone receptors (SR) are hormone-regulated transcription factors belonging to the nuclear receptor family. Upon binding hormone, SR bind to specific enhancer or silencer elements on DNA, recruit many coregulators which remodel chromatin, regulate assembly of the transcription complex, and regulate transcription of the neighboring promoters. Defining the specific molecular functions of the many coregulators and how their recruitment and actions are coordinated are key to understanding how transcription is regulated. Among the many coregulators identified, three complexes are known to have critical roles: the steroid receptor coactivators (SRC) bind directly to SRs and anchor histone modifying enzymes and other coregulators to the promoter;the SWI/SNF complex remodels chromatin in an ATP-dependent manner;and the Mediator complex recruits RNA polymerase II. We have recently discovered two SRC-associated coregulators which are required for recruitment of the SWI/SNF and Mediator complexes to steroid hormone-regulated promoters. With this knowledge we can now progress from coactivator discovery and characterization, which has occupied us and the field for the past 15 years, to the definition of what each coregulator contributes to the process of hormone- stimulated transcription activation and how the recruitment and activities of many of the coregulators are coordinated. This will be done by using RNA interference to systematically deplete the endogenous levels of selected coregulators, followed by chromatin immunoprecipitation assays to examine the effects of coregulator depletion on the stepwise modification of histones and assembly of the transcription complex, which occur on endogenous SR target genes in response to the hormone. This study will go beyond the simple cataloguing of promoter occupancy by defining the stepwise requirements for chromatin modifications and transcription factor assembly and by establishing the functional relationships among the various coregulators, histone modifications, and transcription complex components. We will also define the functions of specific coregulator domains by testing the effect of specific mutations (which disrupt coregulator interactions or functions) on the hormone-dependent regulation of endogenous target genes of SRs. To complement these mechanistic studies, we will also define the physiological gene programs controlled by individual coregulators. We and others have shown that individual coregulators are required for the hormonal regulation of some, but not all, of the target genes of a particular SR in a particular cell line. We will use microarray and bioinformatics analyses to define the subset of SR target genes that require individual coregulators. Then we will examine the specific cellular properties or programs (such as growth and migration) controlled by coregulator-specific subsets of steroid hormone regulated genes. This comprehensive analysis will provide the information necessary to assess whether coregulators are reasonable targets for intervention in breast and prostate cancer and in other steroid hormone-related diseases.

Public Health Relevance

The proposed project will generate a new level of understanding for the molecular mechanism of regulation of genes and cellular activities by steroid hormones. Steroid hormones control normal development and play important roles in diseases such as cancer, diabetes, and autoimmune diseases. The new basic knowledge obtained in this project will identify new potential targets for therapeutic intervention in these diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK043093-21
Application #
8232959
Study Section
Molecular and Cellular Endocrinology Study Section (MCE)
Program Officer
Margolis, Ronald N
Project Start
1990-07-01
Project End
2014-02-28
Budget Start
2012-03-01
Budget End
2013-02-28
Support Year
21
Fiscal Year
2012
Total Cost
$409,393
Indirect Cost
$156,681
Name
University of Southern California
Department
Biochemistry
Type
Schools of Medicine
DUNS #
072933393
City
Los Angeles
State
CA
Country
United States
Zip Code
90089
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Jeong, Kwang Won; Andreu-Vieyra, Claudia; You, Jueng Soo et al. (2014) Establishment of active chromatin structure at enhancer elements by mixed-lineage leukemia 1 to initiate estrogen-dependent gene expression. Nucleic Acids Res 42:2245-56
Wu, Dai-Ying; Ou, Chen-Yin; Chodankar, Rajas et al. (2014) Distinct, genome-wide, gene-specific selectivity patterns of four glucocorticoid receptor coregulators. Nucl Recept Signal 12:e002
Liu, Xingxing; Giguère, Vincent (2014) Inactivation of RAR? inhibits Wnt1-induced mammary tumorigenesis by suppressing epithelial-mesenchymal transitions. Nucl Recept Signal 12:e004
Schiller, Benjamin J; Chodankar, Rajas; Watson, Lisa C et al. (2014) Glucocorticoid receptor binds half sites as a monomer and regulates specific target genes. Genome Biol 15:418
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Ianculescu, Irina; Wu, Dai-Ying; Siegmund, Kimberly D et al. (2012) Selective roles for cAMP response element-binding protein binding protein and p300 protein as coregulators for androgen-regulated gene expression in advanced prostate cancer cells. J Biol Chem 287:4000-13
Won Jeong, Kwang; Chodankar, Rajas; Purcell, Daniel J et al. (2012) Gene-specific patterns of coregulator requirements by estrogen receptor-ýý in breast cancer cells. Mol Endocrinol 26:955-66
Jeong, Kwang Won; Kim, Kyunghwan; Situ, Alan Jialun et al. (2011) Recognition of enhancer element-specific histone methylation by TIP60 in transcriptional activation. Nat Struct Mol Biol 18:1358-65
Jeong, Kwang Won; Lee, Young-Ho; Stallcup, Michael R (2009) Recruitment of the SWI/SNF chromatin remodeling complex to steroid hormone-regulated promoters by nuclear receptor coactivator flightless-I. J Biol Chem 284:29298-309

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