| Structural highlights
Disease
[TET2_HUMAN] Refractory anemia;Polycythemia vera;Acute myeloid leukemia with multilineage dysplasia;Essential thrombocythemia;Myelofibrosis with myeloid metaplasia;Refractory anemia with excess blasts;Acquired idiopathic sideroblastic anemia. TET2 is frequently mutated in myeloproliferative disorders (MPD). These constitute a heterogeneous group of disorders, also known as myeloproliferative diseases or myeloproliferative neoplasms (MPN), characterized by cellular proliferation of one or more hematologic cell lines in the peripheral blood, distinct from acute leukemia. Included diseases are: essential thrombocythemia, polycythemia vera, primary myelofibrosis (chronic idiopathic myelofibrosis). Bone marrow samples from patients display uniformly low levels of hmC in genomic DNA compared to bone marrow samples from healthy controls as well as hypomethylation relative to controls at the majority of differentially methylated CpG sites. The disease is caused by mutations affecting the gene represented in this entry. TET2 is frequently mutated in systemic mastocytosis; also known as systemic mast cell disease. A condition with features in common with myeloproliferative diseases. It is a clonal disorder of the mast cell and its precursor cells. The clinical symptoms and signs of systemic mastocytosis are due to accumulation of clonally derived mast cells in different tissues, including bone marrow, skin, the gastrointestinal tract, the liver, and the spleen. The disease is caused by mutations affecting the gene represented in this entry. Bone marrow samples from patients display uniformly low levels of hmC in genomic DNA compared to bone marrow samples from healthy controls as well as hypomethylation relative to controls at the majority of differentially methylated CpG sites.
Function
[TET2_HUMAN] Dioxygenase that catalyzes the conversion of the modified genomic base 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC) and plays a key role in active DNA demethylation. Also mediates subsequent conversion of 5hmC into 5-formylcytosine (5fC), and conversion of 5fC to 5-carboxylcytosine (5caC). Conversion of 5mC into 5hmC, 5fC and 5caC probably constitutes the first step in cytosine demethylation. Methylation at the C5 position of cytosine bases is an epigenetic modification of the mammalian genome which plays an important role in transcriptional regulation. In addition to its role in DNA demethylation, also involved in the recruitment of the O-GlcNAc transferase OGT to CpG-rich transcription start sites of active genes, thereby promoting histone H2B GlcNAcylation by OGT.[1] [2] [3] [4] [5]
Publication Abstract from PubMed
TET proteins oxidize 5-methylcytosine (5mC) on DNA and play important roles in various biological processes. Mutations of TET2 are frequently observed in myeloid malignance. Here, we present the crystal structure of human TET2 bound to methylated DNA at 2.02 A resolution. The structure shows that two zinc fingers bring the Cys-rich and DSBH domains together to form a compact catalytic domain. The Cys-rich domain stabilizes the DNA above the DSBH core. TET2 specifically recognizes CpG dinucleotide and shows substrate preference for 5mC in a CpG context. 5mC is inserted into the catalytic cavity with the methyl group orientated to catalytic Fe(II) for reaction. The methyl group is not involved in TET2-DNA contacts so that the catalytic cavity allows TET2 to accommodate 5mC derivatives for further oxidation. Mutations of Fe(II)/NOG-chelating, DNA-interacting, and zinc-chelating residues are frequently observed in human cancers. Our studies provide a structural basis for understanding the mechanisms of TET-mediated 5mC oxidation.
Crystal Structure of TET2-DNA Complex: Insight into TET-Mediated 5mC Oxidation.,Hu L, Li Z, Cheng J, Rao Q, Gong W, Liu M, Shi YG, Zhu J, Wang P, Xu Y Cell. 2013 Dec 3. pii: S0092-8674(13)01469-4. doi: 10.1016/j.cell.2013.11.020. PMID:24315485[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Langemeijer SM, Kuiper RP, Berends M, Knops R, Aslanyan MG, Massop M, Stevens-Linders E, van Hoogen P, van Kessel AG, Raymakers RA, Kamping EJ, Verhoef GE, Verburgh E, Hagemeijer A, Vandenberghe P, de Witte T, van der Reijden BA, Jansen JH. Acquired mutations in TET2 are common in myelodysplastic syndromes. Nat Genet. 2009 Jul;41(7):838-42. doi: 10.1038/ng.391. Epub 2009 May 31. PMID:19483684 doi:http://dx.doi.org/10.1038/ng.391
- ↑ Ko M, Huang Y, Jankowska AM, Pape UJ, Tahiliani M, Bandukwala HS, An J, Lamperti ED, Koh KP, Ganetzky R, Liu XS, Aravind L, Agarwal S, Maciejewski JP, Rao A. Impaired hydroxylation of 5-methylcytosine in myeloid cancers with mutant TET2. Nature. 2010 Dec 9;468(7325):839-43. doi: 10.1038/nature09586. PMID:21057493 doi:http://dx.doi.org/10.1038/nature09586
- ↑ He YF, Li BZ, Li Z, Liu P, Wang Y, Tang Q, Ding J, Jia Y, Chen Z, Li L, Sun Y, Li X, Dai Q, Song CX, Zhang K, He C, Xu GL. Tet-mediated formation of 5-carboxylcytosine and its excision by TDG in mammalian DNA. Science. 2011 Sep 2;333(6047):1303-7. doi: 10.1126/science.1210944. Epub 2011 Aug, 4. PMID:21817016 doi:http://dx.doi.org/10.1126/science.1210944
- ↑ Deplus R, Delatte B, Schwinn MK, Defrance M, Mendez J, Murphy N, Dawson MA, Volkmar M, Putmans P, Calonne E, Shih AH, Levine RL, Bernard O, Mercher T, Solary E, Urh M, Daniels DL, Fuks F. TET2 and TET3 regulate GlcNAcylation and H3K4 methylation through OGT and SET1/COMPASS. EMBO J. 2013 Mar 6;32(5):645-55. doi: 10.1038/emboj.2012.357. Epub 2013 Jan 25. PMID:23353889 doi:http://dx.doi.org/10.1038/emboj.2012.357
- ↑ Chen Q, Chen Y, Bian C, Fujiki R, Yu X. TET2 promotes histone O-GlcNAcylation during gene transcription. Nature. 2013 Jan 24;493(7433):561-4. doi: 10.1038/nature11742. Epub 2012 Dec 9. PMID:23222540 doi:http://dx.doi.org/10.1038/nature11742
- ↑ Hu L, Li Z, Cheng J, Rao Q, Gong W, Liu M, Shi YG, Zhu J, Wang P, Xu Y. Crystal Structure of TET2-DNA Complex: Insight into TET-Mediated 5mC Oxidation. Cell. 2013 Dec 3. pii: S0092-8674(13)01469-4. doi: 10.1016/j.cell.2013.11.020. PMID:24315485 doi:http://dx.doi.org/10.1016/j.cell.2013.11.020
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