Genome wide chromatin profile for Histone H1.4 (pan-H1.4) and Phosphorylated H1.4 (pS187-H1.4)

In this study, we use novel, highly specific custom antibodies against a linker histone variant and its modified form to conduct chromatin immunoprecipitation (ChIP) followed by Next Generation Sequencing (NGS) to investigate their binding profiles as a result of transcription inititation. Here we use an estrogen responsive breast cancer cell line, MCF7 to study the enrichment patterns of Histone H1.4 (pan-H1.4) and Phosphorylated H1.4 (pS187-H1.4) across the genome as a result of a short estrogen treatment (30 mins). We find that pS187-H1.4 is preferentially enriched at the promoters of active genes as opposed to the depletion of pan-H1.4 at the same site. Additionally, we use a short treatment of Flavopiridol- an inhibitory drug specific for Cyclin-dependent Kinase-9 (CDK9) which is responsible for the phosphorylation of H1.4 cells, to demonstrate the quenching of this signal at sites specificially activated as a result of the estrogen treatment. This demonstrates for the first time that pS187-H1.4 is associated with active genes and may even be involved in the regulation of gene activity. Examination of Histone H1.4 and pS187H1.4 marks across the genome to evaluate their response to transcription activation