Laboratory of Molecular Growth Regulation, Genomics and Differentiation Program, National Institutes of Child Health and Human Development, National Institutes of Health, Building 6, Room 2A01, 6 Center Drive, Bethesda, MD 20892-2753, United States.
Bromodomains present in Brd4 and other chromatin proteins interact with acetylated histones to regulate transcription and cell growth. To study Brd4-chromatin interactions in vivo, histone H4 tail peptides were fused to a synthetic protein transduction domain (PTD) derived from the human immunodeficiency virus Tat and delivered into cultured cells. Acetyl-H4 peptides, but not unacetylated H4 peptides inhibited real time Brd4-chromatin interactions in living cells as assessed by fluorescence recovery after photobleaching assays. The acetyl-H4 peptides also inhibited an interaction of Brd4 with chromosomes during mitosis and reduced cell growth potential. Together, PTD-based delivery of histone tail peptides offers a novel means to study the mechanism and biological significance of bromodomain-chromatin interactions in vivo.