Reduced Genomic Cytosine Methylation and Defective Cellular Differentiation in Embryonic Stem Cells Lacking CpG Binding Protein

Herman B Wells Center for Pediatric Research, Section of Pediatric Hematology/Oncology, Department of Pediatrics, Indiana School of Medicine, Indianapolis, IN 46202, USA.
Molecular and Cellular Biology (Impact Factor: 4.78). 07/2005; 25(12):4881-91. DOI: 10.1128/MCB.25.12.4881-4891.2005
Source: PubMed


Cytosine methylation at CpG dinucleotides is a critical epigenetic modification of mammalian genomes. CpG binding protein (CGBP) exhibits a unique DNA-binding specificity for unmethylated CpG motifs and is essential for early murine development. Embryonic stem cell lines deficient for CGBP were generated to further examine CGBP function. CGBP(-)(/)(-) cells are viable but show an increased rate of apoptosis and are unable to achieve in vitro differentiation following removal of leukemia inhibitory factor from the growth media. Instead, CGBP(-)(/)(-) embryonic stem cells remain undifferentiated as revealed by persistent expression of the pluripotent markers Oct4 and alkaline phosphatase. CGBP(-)(/)(-) cells exhibit a 60 to 80% decrease in global cytosine methylation, including hypo-methylation of repetitive elements, single-copy genes, and imprinted genes. Total DNA methyltransferase activity is reduced by 30 to 60% in CGBP(-)(/)(-) cells, and expression of the maintenance DNA methyltransferase 1 protein is similarly reduced. However, de novo DNA methyltransferase activity is normal. Nearly all aspects of the pleiotropic CGBP(-)(/)(-) phenotype are rescued by introduction of a CGBP expression vector. Hence, CGBP is essential for normal epigenetic modification of the genome by cytosine methylation and for cellular differentiation, consistent with the requirement for CGBP during early mammalian development.

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Available from: Diana Carlone, Jun 25, 2014
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    • "This study particularly focused on the question of how profiles of this mark are shaped by Cfp1, which is known to be a conserved DNA-binding subunit of the H3K4 histone methyltransferase (HMT) Set1 complex. The experiment presented consists of ChIP-Seq measurements from three different cell lines: (1) a wild-type mouse ES cell line (WT), (2) a mutant ES line lacking Cfp1 (Cfp1-/-) [30,31], and (3) a rescue cell line obtained by stable transfection of a human Cfp1 cDNA into Cfp1-/- ES cells (Resc) [32,33]. We expected that H3K4me3 is reduced in the Cfp1-/- cells. "
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    • "The SET1A complex was purified as a multi-protein complex that associates with CFP1 [19]. CFP1 is required for stem cell differentiation and interacts with unmethylated CpGs via its zinc finger domain CXXC [97]. Interestingly, Cfp1−/− ES cells displayed aberrant H3K4me3 peaks at numerous ectopic sites (i.e., distinct regions outside annotated CpG islands), suggesting that CFP1 recruits the SET1 complex to CpG island-containing promoters and consequently prevents it from generating H3K4me3 to inappropriate chromatin locations [19,98,99]. "
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    • "A similar composite profile for the 20% most affected promoters showed a more drastic depletion of H3K4me3 both upstream of and downstream from the TSS (Fig. 1D,E). To confirm that the absence of Cfp1 was primarily responsible for the observed decrease, we performed H3K4me3 ChIP-seq in a rescue cell line obtained by stable transfection of a human Cfp1 cDNA into Cfp1 À/À ES cells (Carlone et al. 2005; Tate et al. 2009a). These wild-type rescue cells, which express Cfp1 at near endogenous levels "
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