5-hydroxymethylcytosine Marks Mammalian Origins Acting as a Barrier to Replication

Sci Rep. 2019 Jul 30;9(1):11065. doi: 10.1038/s41598-019-47528-3.


In most mammalian cells, DNA replication occurs once, and only once between cell divisions. Replication initiation is a highly regulated process with redundant mechanisms that prevent errant initiation events. In lower eukaryotes, replication is initiated from a defined consensus sequence, whereas a consensus sequence delineating mammalian origin of replication has not been identified. Here we show that 5-hydroxymethylcytosine (5hmC) is present at mammalian replication origins. Our data support the hypothesis that 5hmC has a role in cell cycle regulation. We show that 5hmC level is inversely proportional to proliferation; indeed, 5hmC negatively influences cell division by increasing the time a cell resides in G1. Our data suggest that 5hmC recruits replication-licensing factors, then is removed prior to or during origin firing. Later we propose that TET2, the enzyme catalyzing 5mC to 5hmC conversion, acts as barrier to rereplication. In a broader context, our results significantly advance the understating of 5hmC involvement in cell proliferation and disease states.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-Methylcytosine / analogs & derivatives*
  • 5-Methylcytosine / metabolism
  • Cell Cycle / genetics*
  • Cell Division / physiology*
  • Cell Proliferation / physiology*
  • DNA Replication / physiology*
  • HeLa Cells
  • Humans
  • Replication Origin


  • 5-hydroxymethylcytosine
  • 5-Methylcytosine