Figure 6. The functions of differential histone acylation.
Examples of how different histone acylations are involved in various biological processes. a) Signal-dependent gene activation. Lys crotonylation (Kcr) and Lys acetylation by the histone acyl transferase p300 are induced by the inflammatory signal lipopolysaccharide (not shown) at target genes. Increasing the concentration of crotonyl-CoA (CrCoA) leads to an increase in the levels of p300-catalyzed Kcr, leading to increased recruitment of AF9 and enhanced gene expression. b) Spermatogenesis. Kcr marks X-linked genes that escape meiotic sex chromosome inactivation (MSCI). Histone butyrylation (Kbu) disrupts BRDT binding to chromatin, thereby preventing the histone-to-protamine transition in specific loci in elongating spermatids. c) Metabolic-induced stress. During prolonged starvation, when glucose molecules are scarce, fatty acids replace glucose as the major energy source in the liver. Through the process of ketogenesis, acetyl-CoAs (AcCoA) are converted to ketone bodies, such as β-hydroxybutyrate. β-hydroxybutyrate can then be charged to free coenzyme A to form β-hydroxybutyrate-CoA (bhb-CoA), the high energy donor for the histone modification β-hydroxybutyrylation (Kbhb) is induced in response to ketogenesis and marks a class of activated starvation-response genes.