A DNA Repair Complex Functions as an Oct4/Sox2 Coactivator in Embryonic Stem Cells

Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
Cell (Impact Factor: 32.24). 09/2011; 147(1):120-31. DOI: 10.1016/j.cell.2011.08.038
Source: PubMed

ABSTRACT The transcriptional activators Oct4, Sox2, and Nanog cooperate with a wide array of cofactors to orchestrate an embryonic stem (ES) cell-specific gene expression program that forms the molecular basis of pluripotency. Here, we report using an unbiased in vitro transcription-biochemical complementation assay to discover a multisubunit stem cell coactivator complex (SCC) that is selectively required for the synergistic activation of the Nanog gene by Oct4 and Sox2. Purification, identification, and reconstitution of SCC revealed this coactivator to be the trimeric XPC-nucleotide excision repair complex. SCC interacts directly with Oct4 and Sox2 and is recruited to the Nanog and Oct4 promoters as well as a majority of genomic regions that are occupied by Oct4 and Sox2. Depletion of SCC/XPC compromised both pluripotency in ES cells and somatic cell reprogramming of fibroblasts to induced pluripotent stem (iPS) cells. This study identifies a transcriptional coactivator with diversified functions in maintaining ES cell pluripotency and safeguarding genome integrity.

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Available from: Claudia Cattoglio, Jul 16, 2014
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    • "There are additional examples of DNA repair enzymes functioning as potential coactivators at distal enhancers. The XPC complex can serve both as a classical DNA repair factor and as a transcriptional coactivator in ES cells (Figure 2A) (Fong et al., 2011). Moreover, components of the nucleotide excision repair pathway have been implicated in transcriptional activation upon DNA demethylation and gene looping (Le May et al., 2012), whereas the base-excision repair enzyme TDG is emerging as a key player in regulating DNA methylation (Wyatt, 2013). "
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    ABSTRACT: Comparative genome analyses reveal that organismal complexity scales not with gene number but with gene regulation. Recent efforts indicate that the human genome likely contains hundreds of thousands of enhancers, with a typical gene embedded in a milieu of tens of enhancers. Proliferation of cis-regulatory DNAs is accompanied by increased complexity and functional diversification of transcriptional machineries recognizing distal enhancers and core promoters and by the high-order spatial organization of genetic elements. We review progress in unraveling one of the outstanding mysteries of modern biology: the dynamic communication of remote enhancers with target promoters in the specification of cellular identity.
    Cell 03/2014; 157(1):13-25. DOI:10.1016/j.cell.2014.02.009 · 32.24 Impact Factor
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    • "The complexity of PTMs provides many accessible targets and more possibilities for characterizing hPSCs and directing their differentiation. Like the requirement for protein-protein interaction between POU5F1, SOX2 and a stem cell coactivator complex for the maintenance and establishment of cellular pluripotency172, there could be many novel and important protein functions that rely on appropriate PTMs and cannot be directly identified at the transcriptional or translational levels in stem cells. This necessitates comprehensive investigations of PTMs in hPSCs to uncover critical and yet unknown mechanisms that are responsible for tuning pluripotency-associated signaling and cellular plasticity in hPSCs. "
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    ABSTRACT: Post-translational modifications (PTMs) are known to be essential mechanisms used by eukaryotic cells to diversify their protein functions and dynamically coordinate their signaling networks. Defects in PTMs have been linked to numerous developmental disorders and human diseases, highlighting the importance of PTMs in maintaining normal cellular states. Human pluripotent stem cells (hPSCs), including embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs), are capable of self-renewal and differentiation into a variety of functional somatic cells; these cells hold a great promise for the advancement of biomedical research and clinical therapy. The mechanisms underlying cellular pluripotency in human cells have been extensively explored in the past decade. In addition to the vast amount of knowledge obtained from the genetic and transcriptional research in hPSCs, there is a rapidly growing interest in the stem cell biology field to examine pluripotency at the protein and PTM level. This review addresses recent progress toward understanding the role of PTMs (glycosylation, phosphorylation, acetylation and methylation) in the regulation of cellular pluripotency.Cell Research advance online publication 12 November 2013; doi:10.1038/cr.2013.151.
    Cell Research 11/2013; 24(2). DOI:10.1038/cr.2013.151 · 12.41 Impact Factor
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    • "XPC, which previously was thought to function in GG-NER only, was found to initiate transcription, while CSB remains associated with RNAPII during elongation (Figure 2). XPC also mediates initiation of the transcription of the stem cell inducer Nanog together with Oct4/Sox2 (Fong et al., 2011). The XPF–ERCC1 and XPG endonucleases incise DNA proximal to the promoter and are required for the demethylation that precedes transcription initiation (Le May et al., 2012). "
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    ABSTRACT: DNA damage contributes to cancer development and aging. Congenital syndromes that affect DNA repair processes are characterized by cancer susceptibility, developmental defects, and accelerated aging (Schumacher et al., 2008). DNA damage interferes with DNA metabolism by blocking replication and transcription. DNA polymerase blockage leads to replication arrest and can gives rise to genome instability. Transcription, on the other hand, is an essential process for utilizing the information encoded in the genome. DNA damage that interferes with transcription can lead to apoptosis and cellular senescence. Both processes are powerful tumor suppressors (Bartek and Lukas, 2007). Cellular response mechanisms to stalled RNA polymerase II complexes have only recently started to be uncovered. Transcription-coupled DNA damage responses might thus play important roles for the adjustments to DNA damage accumulation in the aging organism (Garinis et al., 2009). Here we review human disorders that are caused by defects in genome stability to explore the role of DNA damage in aging and disease. We discuss how the nucleotide excision repair system functions at the interface of transcription and repair and conclude with concepts how therapeutic targeting of transcription might be utilized in the treatment of cancer.
    Frontiers in Genetics 02/2013; 4:19. DOI:10.3389/fgene.2013.00019
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