Dysregulation of 2-oxoglutarate-dependent dioxygenases by hyperglycaemia: does this link diabetes and vascular disease?

The clinical, social and economic burden of cardiovascular disease (CVD) associated with diabetes underscores an urgency for understanding the disease aetiology. Evidence suggests that the hyperglycaemia associated with diabetes is, of itself, causal in the development of endothelial dysfunction (ED) which is recognised to be the critical determinant in the development of CVD. It is further recognised that epigenetic modifications associated with changes in gene expression are causal in both the initiation of ED and the progression to CVD. Understanding whether and how hyperglycaemia induces epigenetic modifications therefore seems crucial in the development of preventative treatments. A mechanistic link between energy metabolism and epigenetic regulation is increasingly becoming explored as key energy metabolites typically serve as substrates or co-factors for epigenetic modifying enzymes. Intriguing examples are the ten-eleven translocation and Jumonji C proteins which facilitate the demethylation of DNA and histones respectively. These are members of the 2-oxoglutarate-dependent dioxygenase superfamily which require the tricarboxylic acid metabolite, alpha-ketoglutarate and molecular oxygen (O2) as substrates and Fe (II) as a co-factor. An understanding of precisely how the biochemical effects of high glucose exposure impact upon cellular metabolism, O2 availability and cellular redox in endothelial cells (ECs) may therefore elucidate (in part) the mechanistic link between hyperglycaemia and epigenetic modifications causal in ED and CVD. It would also provide significant proof of concept that dysregulation of the epigenetic landscape may be causal rather than consequential in the development of pathology.