The many metabolic sources of acetyl-CoA to support histone acetylation and influence cancer progression

The fundamental unit of chromatin is the nucleosome which is composed of a histone octamer and the DNA that wraps around it. Histones are globular proteins subject to various reversible covalent modifications that primarily occur on their flexible N-terminal ends (the so-called tail). Histone acetylation is one of these major alterations that may influence the chromatin conformation and consecutively influence gene expression (1). Histone acetylation is usually associated with an increase in transcriptional activity. Indeed, since acetylation occurs on positively charged lysines residues, the addition of an acetyl group on these residues changes the overall charge of the histone tail thereby leading to weaker binding of the nucleosomal components (2). As a direct consequence of histone acetylation, DNA becomes more accessible to transcription factors. Enzymes named histone acetyltransferases (HATs) catalyzed this mode of post-translational modifications (3). Other enzymes termed histone deacetylases (HDACs) are involved in the reverse process of histone deacetylation that restores the ionic interactions between positively charged histones and negatively charged DNA, thereby yielding a more compact chromatin structure (making it harder for transcription factors to bind to the DNA) (2,3).