title: Role of Tet proteins in enhancer activity and telomere elongation.
abstract: DNA methylation at the C-5 position of cytosine (5mC) is one of the best-studied epigenetic modifications and plays important roles in diverse biological processes. Iterative oxidation of 5mC by the ten-eleven translocation (Tet) family of proteins generates 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). 5fC and 5caC are selectively recognized and excised by thymine DNA glycosylase (TDG), leading to DNA demethylation. Functional characterization of Tet proteins has been complicated by the redundancy between the three family members. Using CRISPR/Cas9 technology, we generated mouse embryonic stem cells (ESCs) deficient for all three Tet proteins (Tet triple knockout [TKO]). Whole-genome bisulfite sequencing (WGBS) analysis revealed that Tet-mediated DNA demethylation mainly occurs at distally located enhancers and fine-tunes the transcription of genes associated with these regions. Functional characterization of Tet TKO ESCs revealed a role for Tet proteins in regulating the two-cell embryo (2C)-like state under ESC culture conditions. In addition, Tet TKO ESCs exhibited increased telomere-sister chromatid exchange and elongated telomeres. Collectively, our study reveals a role for Tet proteins in not only DNA demethylation at enhancers but also regulating the 2C-like state and telomere homeostasis.
authors.affiliation: Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Division of Hematology/Oncology, Department of Pediatrics, Boston Children's Hospital, Boston, Massachusetts 02115, USA;
authors.forename: Falong
authors.initials: F
authors.lastname: Lu
authors.affiliation: Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Division of Hematology/Oncology, Department of Pediatrics, Boston Children's Hospital, Boston, Massachusetts 02115, USA;
authors.forename: Yuting
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Division of Hematology/Oncology, Department of Pediatrics, Boston Children's Hospital, Boston, Massachusetts 02115, USA;
authors.forename: Lan
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Division of Hematology/Oncology, Department of Pediatrics, Boston Children's Hospital, Boston, Massachusetts 02115, USA;
authors.forename: Shinpei
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Division of Hematology/Oncology, Department of Pediatrics, Boston Children's Hospital, Boston, Massachusetts 02115, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Harvard Stem Cell Institute, Boston, Massachusetts 02115, USA yzhang@genetics.med.harvard.edu.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000818:Animals; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D049308:Dioxygenases; D053595:Embryonic Stem Cells; D004742:Enhancer Elements, Genetic / Q000502:physiology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D055786:Gene Knockout Techniques; D051379:Mice; D011401:Promoter Regions, Genetic / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D016615:Telomere / Q000235:genetics / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; C540839:TET1 protein, mouse; D049308:Dioxygenases; C551914:Tet2 protein, mouse; C551915:Tet3 protein, mouse
keywords: DNA methylation; demethylation; embryonic stem cell; enhancer; telomere