Histones make up the main protein component of chromatin and are responsible for storing and organizing the genome in a compact yet accessible manner. In addition to storage, histones play an important role in the regulation of various cellular processes such as DNA replication, transcription, and mitosis by regulating the accessibility of DNA to various DNA-binding proteins. Simply put, chromatin exists in “open” and “closed” states. Chromatin in its closed state is inaccessible to DNA-binding proteins like transcription factors while open chromatin is accessible to DNA replication and RNA transcription machinery. Transitions between open and closed chromatin states are carried out through the eviction of nucleosomes or by altering DNA-histone interactions through the post-translational modification of histone proteins. These reactions are carried out by chromatin remodeling complexes. Histone H4 is one of the core structural histones that makes up the nucleosome. H4 can be acetylated or methylated on various residues resulting in transcriptional activation or repression. Monitoring the presence or modification of histones such as H4, at a particular locus or genome-wide provides valuable insight into gene regulation mechanisms.
H4 antibodies have been used to examine changes to global DNA structure during important biological events such as tumorigenesis or cell differentiation. For example, one study by Govin et. al. performed genome wide analysis of H4 modifications during yeast sporulation and meiosis (1). Through chromatin immunoprecipitation with an H4 antibody the group identified a serine phosphorylation site that is responsible for globally blocking transcription and allowing DNA compaction (1). This type of genome wide analysis has been performed for many histone modifications and has helped us to understand the global dynamics of genome regulation. H4 antibodies are an important tool for generating these large data sets, but they have other research applications as well. Immunofluorescence with H4 antibodies provides an excellent nuclear or DNA marker to follow cells undergoing mitosis (2). Additionally, western blotting with H4 antibodies provides a simple way to monitor global histone modifications. Evertts et. al. demonstrated this application in their investigation of H4 methylation during the transition between cell proliferation and quiescence (3). By comparing levels of modified H4 to total H4 they were able to measure H4 methylation at different stages of cell growth (3).
Novus Biologicals offers Histone H4 reagents for your research needs including:
PMIDs
