The methylation status of DNA influences many biological processes during mammalian development, and is known to be highly aberrant in cancer. We recently discovered that the TET proteins TET1, TET2 and TET3 constitute a new family of 1-ketoglutarate (1KG)- and Fe(II)-dependent dioxygenases that alter DNA methylation status by catalysing the oxidation of 5-methylcytosine (5mC) to 5-hydroxy- methylcytosine (5hmC) in DNA. Tet1, Tet2 and 5hmC are present at high levels in mouse embryonic stem (ES) cells and induced pluripotent stem (iPS) cells, suggesting a potential role for 5hmC in pluripotency. Moreover, 5hmC levels and Tet expression/ activity are tightly regulated: 5hmC is present in genomic DNA of undifferentiated ES cells but not several differentiated cell types, and 5hmC levels diminish upon ES cell differentiation. Together these data suggest that dysregulation of DNA methylation via TET proteins and 5hmC may have a role in ES cell differentiation and function. Here we propose to analyze the biological roles of Tet proteins in gene expression, pluripotency and cell fate specification in mouse ES and iPS cells.
In Aim 1, we will study the roles of Tet proteins in mouse ES cell differentiation and function in vitro and in vivo using Tet-deleted ES cells and mice.
In Aim 2, we will examine the requirement for Tet proteins in reprogramming murine fibroblasts to iPS cells.
In Aim 3, we will identify target genes for Tet proteins in ES cells by transcriptional profiling, defining the genomic locations of 5hmC and Tet proteins, and mapping the location of 5hmC at single- base resolution in the genome. The results should provide new insights into the role of the novel base, 5hmC, and the newly-discovered TET family of enzymes, in pluripotency and stem cell function in ES and iPS cells.
Role of TET proteins in ES cell pluripotency and function Narrative In addition to the four major bases in the DNA alphabet - A, C, G and T - there is also a very minor base known as 5-methylcytosine (5mC) that has a disproportionately crucial role. This base is produced from the major base cytosine (C) by attaching a methyl group to its "5" position. Interference with cytosine methylation can lead to a number of developmental abnormalities, genetic diseases and cancer. We recently identified a new class of proteins known as TET proteins that convert 5-methyl- cytosine to a variant known as 5-hydroxymethylcytosine (5hmC). TET proteins and 5-hmC are strongly expressed in mouse embryonic stem (ES) cells, and are induced to high levels when mouse fibroblasts are reprogrammed into induced pluripotent stem (iPS) cells. In this proposal we plan to investigate the role of TET1 and TET2 proteins in ES and iPS cells.
|Ã„ijÃ¶, Tarmo; Huang, Yun; MannerstrÃ¶m, Henrik et al. (2016) A probabilistic generative model for quantification of DNA modifications enables analysis of demethylation pathways. Genome Biol 17:49|
|Etchegaray, Jean-Pierre; Chavez, Lukas; Huang, Yun et al. (2015) The histone deacetylase SIRT6 controls embryonic stem cell fate via TET-mediated production of 5-hydroxymethylcytosine. Nat Cell Biol 17:545-57|
|Kang, Jinsuk; Lienhard, Matthias; Pastor, William A et al. (2015) Simultaneous deletion of the methylcytosine oxidases Tet1 and Tet3 increases transcriptome variability in early embryogenesis. Proc Natl Acad Sci U S A 112:E4236-45|
|Jeong, Mira; Sun, Deqiang; Luo, Min et al. (2014) Large conserved domains of low DNA methylation maintained by Dnmt3a. Nat Genet 46:17-23|
|Iyer, Lakshminarayan M; Zhang, Dapeng; de Souza, Robson F et al. (2014) Lineage-specific expansions of TET/JBP genes and a new class of DNA transposons shape fungal genomic and epigenetic landscapes. Proc Natl Acad Sci U S A 111:1676-83|
|Huang, Yun; Chavez, Lukas; Chang, Xing et al. (2014) Distinct roles of the methylcytosine oxidases Tet1 and Tet2 in mouse embryonic stem cells. Proc Natl Acad Sci U S A 111:1361-6|
|Chavez, Lukas; Huang, Yun; Luong, Khai et al. (2014) Simultaneous sequencing of oxidized methylcytosines produced by TET/JBP dioxygenases in Coprinopsis cinerea. Proc Natl Acad Sci U S A 111:E5149-58|
|Huang, Yun; Rao, Anjana (2014) Connections between TET proteins and aberrant DNA modification in cancer. Trends Genet 30:464-74|
|Ko, Myunggon; An, Jungeun; Bandukwala, Hozefa S et al. (2013) Modulation of TET2 expression and 5-methylcytosine oxidation by the CXXC domain protein IDAX. Nature 497:122-6|
|Koh, Kian Peng; Rao, Anjana (2013) DNA methylation and methylcytosine oxidation in cell fate decisions. Curr Opin Cell Biol 25:152-61|
Showing the most recent 10 out of 28 publications