DNA methylation (5mC) is an important epigenetic modification that plays critical roles in cellular differentiation, development, and disease. In addition to 5-methylcytosine (5mC), substantial amounts of 5-hydroxymethylcytosine (5hmC), which are generated by the TET family of dioxygenases through oxidation of 5-methylcytosine (5mC) (Ito et al., 2010; Iyer et al., 2009; Ko et al., 2010; Kriaucionis and Heintz, 2009; Loenarz and Schofield, 2009; Tahiliani et al., 2009), have been detected in diverse cell types and tissues in mammals (Ito et al., 2010; Ko et al., 2010; Kriaucionis and Heintz, 2009; Szwagierczak et al., 2010; Tahiliani et al., 2009).
Studies have suggested that 5hmC may contribute to DNA demethylation and gene regulation. One possibility is that hydroxylation of mC by TET1 might interfere with DNMT1 activity, leading to a subsequent passive loss of methylation following DNA replication. Alternatively, hmC may be converted to 5-carboxycytosine (5CaC) by Tet dioxygenase. Conversion of 5mC to 5hmC and 5CaC by Tet proteins followed by TDG mediated base excision of 5CaC constitutes a pathway for active DNA demethylation (He et al., 2011). In addition, hydroxylation of mC may promote transcriptional de-repression by dissociation of mC-binding proteins and/or recruitment of effector proteins. The high abundance of hmC in ES cells and in neuronal Purkinje cells and its contribution to DNA demethylation and gene regulation suggests that this modification is important in stem cell biology and cancer (Delhommeau et al., 2009; Ito et al., 2010; Ko et al., 2010; Koh et al., 2011; Tahiliani et al., 2009).
To further understand the role of 5hmC, it is necessary to understand where 5hmC localizes in the genome. By combining hMeDIP (hydroxymethylated DNA immunoprecipitation) with the methylation arrays, Arraystar provide services for methylation arrays designed by Arraystar. This service can identify the genomic location of 5hmC within lncRNA & mRNA promoter regions and other biologically significant genomic regions quickly and cost effectively.
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