title: Drosophila ribosomal proteins are associated with linker histone H1 and suppress gene transcription.
abstract: The dynamics and function of ribosomal proteins in the cell nucleus remain enigmatic. Here we provide evidence that specific components of Drosophila melanogaster ribosomes copurify with linker histone H1. Using various experimental approaches, we demonstrate that this association of nuclear ribosomal proteins with histone H1 is specific, and that colocalization occurs on condensed chromatin in vivo. Chromatin immunoprecipitation analysis confirmed that specific ribosomal proteins are associated with chromatin in a histone H1-dependent manner. Overexpression of either histone H1 or ribosomal protein L22 in Drosophila cells resulted in global suppression of the same set of genes, while depletion of H1 and L22 caused up-regulation of tested genes, suggesting that H1 and ribosomal proteins are essential for transcriptional gene repression. Overall, this study provides evidence for a previously undefined link between ribosomal proteins and chromatin, and suggests a role for this association in transcriptional regulation in higher eukaryotes.
authors.affiliation: Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
authors.forename: Jian-Quan
authors.initials: JQ
authors.lastname: Ni
authors.forename: Lu-Ping
authors.initials: LP
authors.lastname: Liu
authors.forename: Daniel
authors.initials: D
authors.lastname: Hess
authors.forename: Jens
authors.initials: J
authors.lastname: Rietdorf
authors.forename: Fang-Lin
authors.initials: FL
authors.lastname: Sun
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics*; D005786:Gene Expression Regulation; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D012313:RNA / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D029721:Drosophila Proteins; D006657:Histones; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; C489368:RpL22 protein, Drosophila; C512976:RpL7 protein, Drosophila; D012313:RNA