TET2-mediated 5-hydroxymethylcytosine induces genetic instability and mutagenesis

• Published in: DNA repair Vol. 43; pp. 78 - 88
• Main Authors: Mahfoudhi, Emna, Talhaoui, Ibtissam, Cabagnols, Xenia, Della Valle, Véronique, Secardin, Lise, Rameau, Philippe, Bernard, Olivier A., Ishchenko, Alexander A., Abbes, Salem, Vainchenker, William, Saparbaev, Murat, Plo, Isabelle
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.07.2016; Elsevier
• Subjects: 5-hmC; 5-Methylcytosine - analogs & derivatives; 5-Methylcytosine - metabolism; Animals; B-Lymphocytes - cytology; B-Lymphocytes - metabolism; Base Sequence; Biochemistry, Molecular Biology; Cell cycle; Cell Line; Cytosine - analogs & derivatives; Cytosine - metabolism; DNA Repair; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Epigenesis, Genetic; Fibroblasts - cytology; Fibroblasts - metabolism; Genetic instability; Genomic Instability; Genomics; Humans; Hydroxylation; Life Sciences; Megakaryocyte Progenitor Cells - cytology; Megakaryocyte Progenitor Cells - metabolism; Mice; Mutagenesis; Proto-Oncogene Proteins - genetics; Proto-Oncogene Proteins - metabolism; S Phase; TDG; TET2; Thymine DNA Glycosylase - deficiency; Thymine DNA Glycosylase - genetics; Tumor Suppressor Protein p53 - genetics; Tumor Suppressor Protein p53 - metabolism; TET2; Genetic instability; 5-hmC; TDG; Cell cycle
• ISSN: 1568-7864; 1568-7856; 1568-7856
• DOI: 10.1016/j.dnarep.2016.05.031

[Display omitted] •TET2 slows down the S phase of the cell cycle.•TET2 induces chromosomal and centrosomal abnormalities.•TET2-mediated 5-fC or 5-caC elevation in Tdg deficient context leads to mutagenesis. The family of Ten-Eleven Translocation (TET) proteins is implicated in the process of active DNA demethylation and thus in epigenetic regulation. TET 1, 2 and 3 proteins are oxygenases that can hydroxylate 5-methylcytosine (5-mC) into 5-hydroxymethylcytosine (5-hmC) and further oxidize 5-hmC into 5-formylcytosine (5-fC) and 5-carboxylcytosine (5-caC). The base excision repair (BER) pathway removes the resulting 5-fC and 5-caC bases paired with a guanine and replaces them with regular cytosine. The question arises whether active modification of 5-mC residues and their subsequent elimination could affect the genomic DNA stability. Here, we generated two inducible cell lines (Ba/F3-EPOR, and UT7) overexpressing wild-type or catalytically inactive human TET2 proteins. Wild-type TET2 induction resulted in an increased level of 5-hmC and a cell cycle defect in S phase associated with higher level of phosphorylated P53, chromosomal and centrosomal abnormalities. Furthermore, in a thymine-DNA glycosylase (Tdg) deficient context, the TET2-mediated increase of 5-hmC induces mutagenesis characterized by GC>AT transitions in CpG context suggesting a mutagenic potential of 5-hmC metabolites. Altogether, these data suggest that TET2 activity and the levels of 5-hmC and its derivatives should be tightly controlled to avoid genetic and chromosomal instabilities. Moreover, TET2-mediated active demethylation might be a very dangerous process if used to entirely demethylate the genome and might rather be used only at specific loci.