Also see Supplemental Figure 1.
A. Scheme demonstrating the different pathways and enzyme families responsible for 5hmC generation and turnover. DNA methyltransferases (DNMT) methylate cytosine residues at the C-5 carbon to produce 5-methylcytosine (5mC). DNMT1 is responsible for the maintenance of cytosine methylation marks during cell division, whereas DNMT3A and 3B establish de novo cytosine methylation. The TET family of enzymes (TETs) including TET 1, 2 and 3 convert 5mC to 5-hydroxymethylcytosines (5hmC) and further oxidized products 5-formylcytosines (5fC) and 5-carboxylcyosines (5caC) that can be acted upon by the Base-Excision Repair (BER) glycosylase, TDG.
B. Immunostaining of the developing mouse tibial anlagen at embryonic days E11.5 (days post coitus), and growth plate at E13.5 and E17.5 with antibodies specific to 5hmC and Sox9 (red). Nuclei (blue) are counterstained with DAPI. Scale bar = 50µm.