Defining the levels of the chromatin landscape using the I-CATCH system
Alterations of the epigenome, including histone tail post-translational modifications (PTMs), have been shown to regulate the expression of genes important for driving multiple cellular processes including cellular differentiation, aging and tumorigenesis. Although the ability to measure histone tail PTM levels is integral to the understanding of chromatin biology, because of technological limitations, the proportion of nucleosomes that have histone tail PTMs at genomic loci remain undefined. To overcome this limitation, we developed the i mmuno-profiling of d Ca s9 t argeted ch romatin (I-CATCH) system, a technology designed to measure and normalize the levels of nucleosomes and co-occurring histone tail PTMs at targeted loci. Here, we show that the I-CATCH system has high analytical performance for measuring the levels of histone tail PTMs and we report the normalized levels of multiple histone tail PTMs at different genomic loci from both HeLa cells and human plasma. While further studies are required to determine the full utility of the I-CATCH system, we are hopeful that the I-CATCH system will help enable the ability to investigate new important features of chromatin biology.