International Journal of Molecular Sciences
School of Medical and Health Sciences
NIH/NEI grant 1K99EY031741 to Y.S., NIH/NEI grants 1R01EY025794 and R24EY028767 and NIH/NIA grant 1P01AG071463-01A1 to N.Y.F., B.R.K and M.H.F, NIH/NHLBI grant 1R01HL161087 to N.Y.F. and M.H.F., NIH/NEI Schepens Core grant P30EY003790 to B.R.K., an Alcon Young Investigator Grant and a Japan Eye Bank Association Overseas Award to Y.S., and a VA R&D Merit Review Award (1I01RX000989) and a Harvard Stem Cell Institute seed grant award to N.Y.F.
Epigenetic DNA modification by 5-hydroxymethylcytosine (5hmC), generated by the Ten-eleven translocation (TET) dioxygenases, regulates diverse biological functions in many organ tissues, including the mammalian eye. For example, 5hmC has been shown to be involved in epigenetic regulation of retinal gene expression. However, a functional role of 5hmC in corneal differentiation has not been investigated to date. Here, we examined 5hmC and TET function in the human cornea. We found 5hmC highly expressed in MUC16-positive terminally differentiated cells that also co-expressed the 5hmC-generating enzyme TET2. TET2 knockdown (KD) in cultured corneal epithelial cells led to significant reductions of 5hmC peak distributions and resulted in transcriptional repression of molecular pathways involved in corneal differentiation, as evidenced by downregulation of MUC4, MUC16, and Keratin 12. Additionally, integrated TET2 KD RNA-seq and genome-wide Reduced Representation Hydroxymethylation Profiling revealed novel epigenetically regulated genes expressed by terminally differentiated cells, including KRT78, MYEOV, and MAL. In aggregate, our findings reveal a novel function of TET2 in the epigenetic regulation of corneal epithelial gene expression and identify novel TET2-controlled genes expressed in differentiated corneal epithelial cells. These results point to potential roles for TET2 induction strategies to enhance treatment of corneal diseases associated with abnormal epithelial maturation.
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