title: Transcriptional activation of histone H4 by C/EBPβ during the mitotic clonal expansion of 3T3-L1 adipocyte differentiation.
abstract: CCAAT enhancer binding protein β (C/EBPβ) is required for both mitotic clonal expansion (MCE) and terminal differentiation during the 3T3-L1 adipocyte differentiation program. Whereas the mechanism of C/EBPβ during terminal differentiation is well understood, the mechanism of C/EBPβ in MCE is not. We provide evidence that histone H4, the most conserved cell cycle-related histone, the change of which is strictly correlated with DNA content change during the cell cycle, is transcriptionally activated by C/EBPβ during MCE. Expression of histone H4 is increased at 16 h after induction when 3T3-L1 preadipocytes synchronously reenter S phase, which is correlated with the sequential phosphorylation and activation of C/EBPβ, and expression was partially suppressed when A-C/EBP (dominant negative for C/EBP protein) was overexpressed. One C/EBP-binding site was identified in one of the histone H4 gene promoters (hist4h4), confirmed by both electrophoretic mobility shift assay and chromatin immunoprecipitation assay. C/EBP-binding sites were also found in 9 of 11 other histone H4 promoters, which can also be transactivated by C/EBPβ. Knockdown of C/EBPβ by stealth small interfering RNA partially decreased H4 gene expression and arrested cells in G1 phase as indicated by bromodeoxyuridine incorporation and fluorescence-activated cell sorting analysis of DNA content. This study provides new insights into why C/EBPβ is required for MCE during 3T3-L1 adipocyte differentiation and why C/EBPβ plays important roles in the proliferation of other cell types.
authors.affiliation: The Key Laboratory of Molecular Medicine, Ministry of Education, Department of Biochemistry and Molecular Biology, Fudan University Shanghai Medical College, Shanghai 200032, China.
authors.forename: You-You
authors.initials: YY
authors.lastname: Zhang
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.forename: Shu-Wen
authors.initials: SW
authors.lastname: Qian
authors.forename: Liang
authors.initials: L
authors.lastname: Guo
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Huang
authors.forename: Qun
authors.initials: Q
authors.lastname: He
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.forename: Chun-Gu
authors.initials: CG
authors.lastname: Ma
authors.forename: Qi-Qun
authors.initials: QQ
authors.lastname: Tang
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D047369:Chromatin Immunoprecipitation / Q000379:methods; D005434:Flow Cytometry / Q000379:methods; D016193:G1 Phase / Q000502:physiology; D006657:Histones / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D051379:Mice; D008938:Mitosis / Q000502:physiology; D010766:Phosphorylation / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D016196:S Phase / Q000502:physiology; D015533:Transcriptional Activation
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; D006657:Histones