Identification of Transcription Complexes that Contain the Double Bromodomain Protein Brd2 and Chromatin Remodeling Machines

Boston University, Boston, Massachusetts, United States
Journal of Proteome Research (Impact Factor: 4.25). 04/2006; 5(3):502-11. DOI: 10.1021/pr050430u
Source: PubMed


We use affinity purification of the double bromodomain protein Brd2 to isolate a multicomponent nuclear complex from cultured cells, and apply mass spectrometry/proteomics methods to identify the participants. We then confirm by immunoblot several transcription co-activators and co-repressors, proteins of the Swi/Snf chromatin remodeling complex, which regulate transcription control of cyclin A. This multiprotein complex is likely to contribute to cell cycle control and play a role in proliferation and cancer.

Download full-text


Available from: Mark E Mccomb, Oct 07, 2015
25 Reads
  • Source
    • "Further, the transcriptional repressors remodeling and spacing factor 1 (rsf1) and mbt domain containing 1 [39] were present in unfertilized and fertilized oocytes, respectively. A maternally supplied co-activator bromodomain containing 2 (brd2) [40, 41] can be important for the early embryo cell cycle control. Fertilized oocytes contained transcripts for a protein involved in DNA methylation (PWWP domain containing 2 isoform 1). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Background Regulation of gene expression plays a central role in embryonic development. Early stages are controlled by gametic transcripts, which are subsequently substituted with transcripts from the genome of the zygote. Transcriptomic analyses provide an efficient approach to explore the temporal gene expression profiles in embryos and to search for the developmental regulators. We report a study of early Atlantic cod development that used a genome-wide oligonucleotide microarray to examine the composition and putative roles of polyadenylated transcripts. Results The analyses were carried out in unfertilized oocytes, newly fertilized oocytes and embryos at the stages of mid-blastula transition and segmentation. Numerous genes transcribed in oocytes are involved in multiple aspects of cell maintenance and protection, including metabolism, signal perception and transduction, RNA processing, cell cycle, defense against pathogens and DNA damage. Transcripts found in unfertilized oocytes also encoded a large number of proteins implicated in cell adherence, tight junction and focal adhesion, suggesting high complexity in terms of structure and cellular interactions in embryos prior to midblastula transition (MBT). Prezygotic transcripts included multiple regulators that are most likely involved in developmental processes that take place long after fertilization, such as components of ErbB, hedgehog, notch, retinoid, TGFb, VEGF and Wnt signaling pathways, as well as transcripts involved in the development of nervous system. The major event of MBT was the activation of a large group of histones and other genes that modify chromatin structure preceding massive gene expression changes. A hallmark of events observed during segmentation was the induction of multiple transcription factors, including a large group of homeobox proteins in pace with decay of a large fraction of maternal transcripts. Microarray analyses detected a suite of master developmental regulators that control differentiation and maintenance of diverse cell lineages. Conclusions Transcriptome profiling of the early stages in Atlantic cod revealed the presence of transcripts involved in patterning and development of tissues and organs long before activation of the zygotic genome. The switch from maternal to zygotic developmental programs is associated with large-scale modification of chromosomes. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-594) contains supplementary material, which is available to authorized users.
    BMC Genomics 07/2014; 15(1):594. DOI:10.1186/1471-2164-15-594 · 3.99 Impact Factor
  • Source
    • "Bromodomain-containing protein 2 (Brd2) is a nuclear transcription factor kinase that acts as a co-regulator in the regulation of gene transcription [24]. Previous studies have shown that Brd2 can bind transcriptional activators like E2F proteins, and coactivator TATA binding factor (TBP)-associated factors (TAFs), members of the SWItch/sucrose nonfermentable (SWI/SNF) complex, histone acetyltransferases (HATs) and histone deacetylases (HDACs) to regulate the expression of diverse genes [25]. A nuclear/cytoplasmic translocation of Brd2 protein has been observed in cultured mouse fibroblasts as well as in mammary epithelial cells during the reproductive cycle, correlating with both proliferation and apoptosis [26]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Bromodomain-containing protein 2 (Brd2) is a nuclear serine/threonine kinase involved in transcriptional regulation. In 3T3-L1 adipocytes, Brd2 normally co-represses PPARγ (peroxisome proliferator-activated receptor gamma) and inhibits adipogenesis. Here, we show that Brd2 over-expression in preadipocytes inhibits their differentiation into adipocytes, while Brd2 knockdown promotes adipogenic differentiation in vitro and forces cells to undergo adipogenesis independent of the MDI (methyisobutylxanthane, dexamethasone and insulin) induction. In this study, the two key transcription factors for adipogenesis, PPARγ and C/EBPα (CCAAT/enhancer binding protein-α) were persistently expressed during the differentiation of preadipocytes to mature adipocytes in Brd2 knockdown 3T3-L1 cells, but their expression was inhibited in cells in which Brd2 was overexpressed. To investigate the role of Brd2 in signal transduction we examined the expression of several signaling molecules involved in the regulation of gene expression and cell differentiation by immunoblotting assay. Down-regulation of Brd2 expression in 3T3-L1 cells led to a decrease in extracellular signal-regulated kinase1/2 (ERK1/2) activity and, conversely, the up-regulation of Brd2 leads to increase in ERK1/2 phosphorylation. Nevertheless, changes in Brd2 expression do not affect the activities of JNK and p38 MAPK. In addition, the phosphorylation of Rafs is not affected by changes in Brd2 expression in 3T3-L1 cells. MEK inhibitor UO126 partly restores differentiation of 3T3-L1 cells that overexpress Brd2. In conclusion, these results indicate that Brd2 regulates ERK1/2 activity independently of Raf signaling in 3T3-L1 adipocytes.
    PLoS ONE 10/2013; 8(10):e78536. DOI:10.1371/journal.pone.0078536 · 3.23 Impact Factor
  • Source
    • "BRD4 regulates a number of genes essential for cell growth through the recruitment and maintenance of the pTEFb complex at gene promoters during mitosis [4,5]. BRD2 interacts with a number of transcription factors, including E2F family members, and regulates the expression of several E2F-dependent cell cycle genes [6,7]. While less is known about BRD3 and the testis-specific BRDT, both proteins bind to acetylated histones to promote transcription of growth-associated genes (BRD3) or chromatin remodeling (BRDT) [8,9]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: BET family proteins are epigenetic regulators known to control expression of genes involved in cell growth and oncogenesis. Selective inhibitors of BET proteins exhibit potent anti-proliferative activity in a number of hematologic cancer models, in part through suppression of the MYC oncogene and downstream Myc-driven pathways. However, little is currently known about the activity of BET inhibitors in solid tumor models, and whether down-regulation of MYC family genes contributes to sensitivity. Here we provide evidence for potent BET inhibitor activity in neuroblastoma, a pediatric solid tumor associated with a high frequency of MYCN amplifications. We treated a panel of neuroblastoma cell lines with a novel small molecule inhibitor of BET proteins, GSK1324726A (I-BET726), and observed potent growth inhibition and cytotoxicity in most cell lines irrespective of MYCN copy number or expression level. Gene expression analyses in neuroblastoma cell lines suggest a role of BET inhibition in apoptosis, signaling, and N-Myc-driven pathways, including the direct suppression of BCL2 and MYCN. Reversal of MYCN or BCL2 suppression reduces the potency of I-BET726-induced cytotoxicity in a cell line-specific manner; however, neither factor fully accounts for I-BET726 sensitivity. Oral administration of I-BET726 to mouse xenograft models of human neuroblastoma results in tumor growth inhibition and down-regulation MYCN and BCL2 expression, suggesting a potential role for these genes in tumor growth. Taken together, our data highlight the potential of BET inhibitors as novel therapeutics for neuroblastoma, and suggest that sensitivity is driven by pleiotropic effects on cell growth and apoptotic pathways in a context-specific manner.
    PLoS ONE 08/2013; 8(8):e72967. DOI:10.1371/journal.pone.0072967 · 3.23 Impact Factor
Show more