title: The chromatin remodeling factor CSB recruits histone acetyltransferase PCAF to rRNA gene promoters in active state for transcription initiation.
abstract: The promoters of poised rRNA genes (rDNA) are marked by both euchromatic and heterochromatic histone modifications and are associated with two transcription factors, UBF and SL1 that nucleate transcription complex formation. Active rRNA genes contain only euchromatic histone modifications and are loaded with all components of transcriptional initiation complex including RNA polymerase I. Coupled with histone acetylation and RNA polymerase I targeting, poised promoters can be converted to active ones by ATP-dependent chromatin remodeling factor CSB for initiation of rDNA transcription. However, it is not clear how dynamic histone modifications induce the assembly of polymerase I transcription initiation complex to active promoters during such conversion. Here we show that a complex consisting of CSB, RNA polymerase I and histone acetyltransferase PCAF is present at the rDNA promoters in active state. CSB is required for the association of PCAF with rDNA, which induces acetylation of histone H4 and histone H3K9. Overexpression of CSB promotes the association of PCAF with rDNA. Knockdown of PCAF leads to decreased levels of H4ac and H3K9ac at rDNA promoters, prevents the association of RNA polymerase I and inhibits pre-rRNA synthesis. The results demonstrate that CSB recruits PCAF to rDNA, which allows histone acetylation that is required for the assembly of polymerase I transcription initiation complex during the transition from poised to active state of rRNA genes, suggesting that CSB and PCAF play cooperative roles to establish the active state of rRNA genes by histone acetylation.
authors.affiliation: Key Laboratory of Cell Proliferation and Differentiation, National Key Laboratory of Protein Engineering and Plant Gene Engineering, College of Life Science, Peking University, Beijing, China.
authors.forename: Meili
authors.initials: M
authors.lastname: Shen
authors.forename: Tingting
authors.initials: T
authors.lastname: Zhou
authors.forename: Wenbing
authors.initials: W
authors.lastname: Xie
authors.forename: Te
authors.initials: T
authors.lastname: Ling
authors.forename: Qiaoyun
authors.initials: Q
authors.lastname: Zhu
authors.forename: Le
authors.initials: L
authors.lastname: Zong
authors.forename: Guoliang
authors.initials: G
authors.lastname: Lyu
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Gao
authors.forename: Feixiong
authors.initials: F
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Tao
mesh_terms: D000107:Acetylation; D000818:Animals; D042002:Chromatin Assembly and Disassembly; D004265:DNA Helicases / Q000378:metabolism*; D045643:DNA Repair Enzymes / Q000378:metabolism*; D057809:HEK293 Cells; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000378:metabolism; D051379:Mice; D041681:NIH 3T3 Cells; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism; D000075223:Poly-ADP-Ribose Binding Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012318:RNA Polymerase I / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics*; D061785:Transcription Initiation, Genetic; D050880:p300-CBP Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D000099224:p300-CBP-Associated Factor
chemical_list: D004265:DNA Helicases; D045643:DNA Repair Enzymes; D006657:Histones; D008239:Lysine; D009707:Nucleosomes; D000075223:Poly-ADP-Ribose Binding Proteins; D012318:RNA Polymerase I; D012335:RNA, Ribosomal; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C078673:ERCC6 protein, human; C513075:Ercc6 protein, mouse