CXXC finger protein 1 contains redundant functional domains that support embryonic stem cell cytosine methylation, histone methylation, and differentiation.

Departments of Pediatrics and Biochemistry and Molecular Biology, Indiana University School of Medicine, 1044 West Walnut St., Room 327, Indianapolis, IN 46202, USA.
CXXC finger protein 1 (Cfp1) is a regulator of both cytosine methylation and histone methylation. Murine embryonic stem (ES) cells lacking Cfp1 exhibit a decreased plating efficiency, decreased cytosine methylation, elevated global levels of histone H3-Lys4 trimethylation, and a failure to differentiate in vitro. Remarkably, transfection studies reveal that expression of either the amino half of Cfp1 (amino acids 1 to 367 [Cfp1(1-367)]) or the carboxyl half of Cfp1 (Cfp1(361-656)) is sufficient to correct all of the defects observed with ES cells that lack Cfp1. However, a point mutation (C169A) that abolishes DNA-binding activity of Cfp1 ablates the rescue activity of the Cfp1(1-367) fragment, and a point mutation (C375A) that abolishes the interaction of Cfp1 with the Setd1 histone H3-Lys4 methyltransferase complexes ablates the rescue activity of the Cfp1(361-656) fragment. Introduction of both the C169A and C375A point mutations ablates the rescue activity of the full-length Cfp1 protein. These results indicate that retention of either the Cfp1 DNA-binding domain or Setd1 interaction domain is required for Cfp1 rescue activity, and they illustrate the functional complexity of this critical epigenetic regulator. A model is presented for how epigenetic cross talk may explain the finding of redundant functional domains within Cfp1.
Mesh Terms:
Amino Acid Sequence, Amino Acid Substitution, Animals, Base Sequence, Binding Sites, Cell Differentiation, Cell Line, Cytosine, DNA Methylation, DNA Primers, DNA-Binding Proteins, Embryonic Stem Cells, Epigenesis, Genetic, Histones, Humans, Mice, Mice, Knockout, Models, Biological, Molecular Sequence Data, Mutagenesis, Site-Directed, Peptide Fragments, Protein Structure, Tertiary, Sequence Homology, Amino Acid, Trans-Activators, Transfection
Mol. Cell. Biol. Jul. 01, 2009; 29(14);3817-31 [PUBMED:19433449]
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