BioProject

Variation in chromatin composition and organization often reflects differences in genome function. More...

Variation in chromatin composition and organization often reflects differences in genome function. Histone variants, for example, replace canonical histones to contribute to regulation of numerous nuclear processes including transcription, DNA repair and chromosome segregation. Here we focus on H2A.Bbd, a rapidly evolving variant found in mammals but not in invertebrates. We report that in human cells, nucleosomes bearing H2A.Bbd form unconventional chromatin structures enriched within actively transcribed genes and characterized by shorter DNA protection and nucleosome spacing. Analysis of transcriptional profiles from cells depleted for H2A.Bbd demonstrated widespread changes in gene expression with a net down-regulation of transcription and disruption of normal mRNA splicing patterns. In particular, we observed changes in exon inclusion rates and increased presence of intronic sequences in mRNA products upon H2A.Bbd depletion. Taken together, our results indicate that H2A.Bbd is involved in formation of a specific chromatin structure that facilitates both transcription and initial mRNA processing. Overall design: RNA-seq was used to examine changes in gene expression upon shRNA-assisted depletion of H2A.Bbd and H2A.Z histone variants in HeLa cells. The cells treated with shRNA with no homology to the human genome were used as control. Less...