TET1

TET1 (ten-eleven translocation 1) is a member of the TET family of Fe(II)- and α-ketoglutarate-dependent dioxygenases that catalyze the oxidation of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), thereby contributing to active DNA demethylation and epigenetic regulation[1][2]. TET1 preferentially binds CpG-rich promoter regions and regulates gene expression through modulation of local DNA methylation states, linking hydroxymethylation to transcriptional control and cellular identity maintenance[2]. Mechanistically, TET1 functions in both transcriptional activation and repression, as promoter hypomethylation supports expression of transcriptionally active genes, whereas recruitment of repressive complexes to CpG-rich promoters contributes to silencing of developmental regulators in embryonic stem cells[2]. Therefore, TET1 plays an important role in pluripotency, lineage commitment, and stem-cell state transitions through coordinated epigenetic remodeling[2][3]. In disease contexts, aberrant TET1 activity has been associated with multiple human disorders, including hematologic malignancies and solid tumors, where altered DNA demethylation programs affect gene expression networks involved in disease progression[4][5]. Compared with related isoforms TET2 and TET3, TET1 shows a distinctive preference for promoter-associated CpG-rich regions and primarily regulates 5hmC levels around transcription start sites, highlighting a specialized role in promoter-centered epigenetic regulation[3]. For experimental applications, TET1 is widely used as a model enzyme for studying DNA hydroxymethylation, epigenetic reprogramming, and methylation-dependent gene regulation in stem-cell and disease research[1][2].