This December, we celebrate the 100th
anniversary of Albrecht Kossel’s 1910 Nobel Prize in Physiology or Medicine, which was awarded in part for his discovery of histone proteins1
. Soon after elucidation of the DNA-RNA-Protein ‘Central Dogma’, a 1964 paper presented strong experimental evidence that histones are acetylated and methylated after completion of the polypeptide chain, and that these histone modifications “affect the capacity of the histones to inhibit ribonucleic acid synthesis in vivo
. This work foreshadowed a very active period since the early 1990s, which has brought an explosion of insight regarding how DNA is packaged into chromatin, the multitude of enzymes that modify key histone residues in eukaryotic cells, and how those marks are associated with diverse functional states of chromatin3
Key to these recent advances has been the availability of antibodies to dozens of specific post-translational modifications on histones, coupled with the advent of Chromatin Immunoprecipitation (ChIP), DNA microarrays (ChIP-chip), and highly parallel DNA sequencing (ChIP-seq). This combination of antibodies and technology has enabled investigators to determine the genomic distributions of histone modifications and to connect them with biological functions3
. However, the reproducibility and biological relevance of histone-modification landscapes depends on the specificity and performance of the antibodies, most of which are now provided commercially. The validity of results could be affected by recognition of unmodified histones, non-target modifications, and non-histone proteins. In addition, antibodies may exhibit appropriate specificity, but be ineffective ChIP reagents.
Here we set out to assess the quality of histone-modification antibodies by western blot, dot blot, and ChIP-chip or ChIP-seq analysis.