Purification of H3 and H4 Histone Proteins and the Quantification of Acetylated Histone Marks in Cells and Brain Tissue.

In all eukaryotic organisms, chromatin, the physiological template of all genetic information, is essential for heredity. Chromatin is subject to an array of diverse posttranslational modifications (PTMs) that mostly occur in the amino termini of histone proteins (i.e., histone tail) and regulate the accessibility and functional state of the underlying DNA. Histone tails extend from the core of the nucleosome and are subject to the addition of acetyl groups by histone acetyltransferases (HATs) and the removal of acetyl groups by histone deacetylases (HDACs) during cellular growth and differentiation. Specific acetylation patterns on lysine (K) residues on histone tails determine a dynamic homeostasis between transcriptionally active or transcriptionally repressed chromatin by (1) influencing the core histone assembly and (2) recruiting synergistic or antagonistic chromatin-associated proteins to the transcription site. The fundamental regulatory mechanism of the complex nature of histone tail PTMs influences the majority of chromatin-templated processes and results in changes in cell maturation and differentiation in both normal and pathological development. The goal of the current report is to provide novices with an efficient method to purify core histone proteins from cells and brain tissue and to reliably quantify acetylation marks on histones H3 and H4.