title: The E2F transcription factor family regulates CENH3 expression in Arabidopsis thaliana.
abstract: To elucidate the epigenetic maintenance mechanism for functional plant centromeres, we studied transcriptional regulation of the centromere-specific histone H3 variant CENH3 in Arabidopsis thaliana. We focused on the structure and activity of the CENH3 promoter (CENH3pro) and its regulation by E2F transcription factors. Use of CENH3pro::GUS reporter gene constructs showed that CENH3pro is active in dividing tissues, and that full expression in root meristems depends on intragenic regulatory elements within the second intron. Chromatin immunoprecipitation identified CENH3 as an E2F target gene. Transient co-expression of a CENH3pro::GUS reporter gene construct with various E2F transcription factors in A. thaliana protoplasts showed that E2Fa and E2Fb (preferentially with dimerization protein DPb) activate CENH3pro. Stable over-expression of E2Fa and E2Fb increased the CENH3 transcript level in planta, whereas over-expression of E2Fc decreased the CENH3 transcript level. Surprisingly, mutation of the two E2F binding sites of CENH3pro, in particular the more upstream one (E2F2), caused an increase in CENH3pro activity, indicating E2F-dependent transcriptional repression. CENH3pro repression may be triggered by the interplay of typical and atypical E2Fs in a cell cycle-dependent manner, and/or by interaction of typical E2Fs with retinoblastoma-related (RBR) protein. We speculate that E2Fs are involved in differential transcriptional regulation of CENH3 versus H3, as H3 promoters lack E2F binding motifs. E2F binding motifs are also present in human and Drosophila CENH3pro regions, thus cell cycle-dependent transcriptional regulation of CENH3 may be highly conserved.
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, Corrensstraße 3, 06466 Gatersleben, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Heckmann
authors.forename: Inna
authors.initials: I
authors.lastname: Lermontova
authors.forename: Barbara
authors.initials: B
authors.lastname: Berckmans
authors.forename: Lieven
authors.initials: L
authors.lastname: De Veylder
authors.forename: Helmut
authors.initials: H
authors.lastname: Bäumlein
authors.forename: Ingo
authors.initials: I
authors.lastname: Schubert
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D047369:Chromatin Immunoprecipitation; D050684:E2F Transcription Factors / Q000235:genetics / Q000378:metabolism*; D044127:Epigenesis, Genetic; D018506:Gene Expression Regulation, Plant; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic
chemical_list: D029681:Arabidopsis Proteins; D050684:E2F Transcription Factors; D006657:Histones