title: Nucleophosmin/B23 negatively regulates GCN5-dependent histone acetylation and transactivation.
abstract: Nucleophosmin/B23 is a multifunctional phosphoprotein that is overexpressed in cancer cells and has been shown to be involved in both positive and negative regulation of transcription. In this study, we first identified GCN5 acetyltransferase as a B23-interacting protein by mass spectrometry, which was then confirmed by in vivo co-immunoprecipitation. An in vitro assay demonstrated that B23 bound the PCAF-N domain of GCN5 and inhibited GCN5-mediated acetylation of both free and mononucleosomal histones, probably through interfering with GCN5 and masking histones from being acetylated. Mitotic B23 exhibited higher inhibitory activity on GCN5-mediated histone acetylation than interphase B23. Immunodepletion experiments of mitotic extracts revealed that phosphorylation of B23 at Thr 199 enhanced the inhibition of GCN5-mediated histone acetylation. Moreover, luciferase reporter and microarray analyses suggested that B23 attenuated GCN5-mediated transactivation in vivo. Taken together, our studies suggest a molecular mechanism of B23 in the mitotic inhibition of GCN5-mediated histone acetylation and transactivation.
authors.affiliation: Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Yonglong
authors.initials: Y
authors.lastname: Zou
authors.forename: Jun
authors.initials: J
authors.lastname: Wu
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Giannone
authors.forename: Lorrie
authors.initials: L
authors.lastname: Boucher
authors.forename: Hansen
authors.initials: H
authors.lastname: Du
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Dabney K
authors.initials: DK
authors.lastname: Johnson
authors.forename: Yie
authors.initials: Y
authors.lastname: Liu
authors.forename: Yisong
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000107:Acetylation; D000818:Animals; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008938:Mitosis / Q000502:physiology; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000090243:Nucleophosmin; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary / Q000502:physiology; D015533:Transcriptional Activation / Q000502:physiology*; D050880:p300-CBP Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000099224:p300-CBP-Associated Factor
chemical_list: D006657:Histones; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D009707:Nucleosomes; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C000716967:NPM1 protein, human; C000715570:Npm1 protein, mouse