The Elusive Role of 5′-Hydroxymethylcytosine

Abstract

5′-hydroxymethylcytosine (5hmC) is a variant of the common covalent epigenetic modification of DNA 5′-methylcytosine (5mC). Although the presence of this modified base in mammalian DNA has been recognized for several decades, it has recently gained center stage as a suspected intermediate in enzymatic active demethylation of 5mC. The role of 5hmC remains elusive in spite of a large body of studies. It is proposed that 5hmC is a variant of the 5mC epigenetic signal and is involved in epigenetic regulation of gene function. Recent data support a role for 5hmC in the activation of lineage-specific enhancers.

Keywords::

• active demethylation
• cellular differentiation
• DNA methylation
• enhancers
• global demethylation
• hydroxymethylation
• oxidases
• stem cells

Financial & competing interests disclosure

The work in M Szyf’s laboratory was supported by a grant from the Canadian Institute of Health Research MOP-424111. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Additional information

Funding

The work in M Szyf’s laboratory was supported by a grant from the Canadian Institute of Health Research MOP-424111. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.