Abstract
Ketone bodies are short chain fatty acids produced in the liver during periods of limited glucose availability that provide an alternative source of energy for the brain, heart, and skeletal muscle. Beyond this classical metabolic role, β-hydroxybutyrate (BHB), is gaining recognition as a pleiotropic signaling molecule. Lysine β-hydroxybutyrylation (Kbhb) is a newly discovered post-translational modification in which BHB is covalently attached to lysine ε-amino groups. This novel protein adduct is metabolically sensitive, dependent on BHB concentration, and found on proteins in multiple intracellular compartments, including the mitochondria and nucleus. Therefore, Kbhb is hypothesized to be an important component of ketone body-regulated physiology. Kbhb on histones is proposed to be an epigenetic regulator, which links metabolic alterations to gene expression. However, we found that the widely used antibody against the β-hydroxybutyrylated lysine 9 on histone H3 (H3K9bhb) also recognizes other modification(s), which are increased by deacetylation inhibition and include likely acetylations. Therefore, caution must be used when interpreting gene regulation data acquired with the H3K9bhb antibody.