Repression of gene expression involves the binding of transcriptional repressors to promoter elements, which in turn recruit co regulators that are part of large complexes with various chromatin modifying activities. There are multiple epigenetic modifications of chromatin that contribute to transcriptional repression that include histone acetylation and methylation, and DNA methylation. Transcriptional repression can vary from decreases in expression levels to reversible silencing of a gene to irreversible silencing of a gene. Understanding how genes are repressed to different degrees will yield greater understanding of basic processes that underlie development, differentiation and homeostasis and will have implications for providing greater understanding of diseases that disrupt these central processes. The Oct4 gene represents an excellent model system to dissect transcriptional repression and silencing. Oct4 is expressed in embryonic stem (ES) cells in developing embryos and upon gastrulation its expression is repressed and eventually silenced in somatic cells. We identified the transcription factor that plays a pivotal in this process the orphan nuclear receptor Germ Cell Nuclear Factor (GCNF), which is a transcriptional repressor. In order to understand the mechanism of repression of Oct4 we used a yeast two hybrid screen to identify GCNF interacting factors. We identified the co-repressor NCoR, the methylated DNA binding factors (MBDs) and DNA Methyl transferases (DNMTs) as factors that specifically interact with GCNF. We propose to test the hypothesis that GCNF mediates repression and silencing of Oct4 expression by the sequential recruitment of multiple factors involved in chromatin modification by execution of the following specific aims: 1, Analysis of Oct4 repression and silencing in differentiating P19 and ES cells, focusing on chromatin modifications, factor recruitment and gene silencing. 2, Analysis of the role of NCoR and SMRT in Oct4 repression. 3, Analysis of the role of MBDs in Oct4 repression. 4 Analysis of the role of DNMTs in Oct4 repression. 5, Analysis of the regulation of Oct4 repression in human ES cells (NIH Code BG01) from Bresagen Inc. The culminating of these experiments will have profound implications for manipulation of human ES cells for therapeutic purposes and somatic cell nuclear transfer into oocytes, which relies on the re-expression of silenced Oct4 and cancers in which the Oct4 is mis-expressed.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
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Margolis, Ronald N
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Baylor College of Medicine
Anatomy/Cell Biology
Schools of Medicine
United States
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Wang, Hongran; Wang, Xiaohong; Archer, Trevor K et al. (2014) GCNF-dependent activation of cyclin D1 expression via repression of Mir302a during ESC differentiation. Stem Cells 32:1527-37
Wang, Hongran; Wang, Xiaohong; Xu, Xueping et al. (2013) Epigenetic reprogramming of the germ cell nuclear factor gene is required for proper differentiation of induced pluripotent cells. Stem Cells 31:2659-66
Wagner, Ryan T; Xu, Xueping; Yi, Fei et al. (2010) Canonical Wnt/ýý-catenin regulation of liver receptor homolog-1 mediates pluripotency gene expression. Stem Cells 28:1794-804
Lan, Zi-Jian; Xu, Xueping; Chung, Arthur C-K et al. (2009) Extra-germ cell expression of mouse nuclear receptor subfamily 6, group A, member 1 (NR6A1). Biol Reprod 80:905-12
Liang, Jiancong; Wan, Ma; Zhang, Yi et al. (2008) Nanog and Oct4 associate with unique transcriptional repression complexes in embryonic stem cells. Nat Cell Biol 10:731-9
Chung, Arthur C-K; Xu, Xueping; Niederreither, Karen A et al. (2006) Loss of orphan nuclear receptor GCNF function disrupts forebrain development and the establishment of the isthmic organizer. Dev Biol 293:13-24
Gu, Peili; LeMenuet, Damien; Chung, Arthur C-K et al. (2005) Orphan nuclear receptor GCNF is required for the repression of pluripotency genes during retinoic acid-induced embryonic stem cell differentiation. Mol Cell Biol 25:8507-19