title: Interplay between Arabidopsis activating factors E2Fb and E2Fa in cell cycle progression and development.
abstract: Eukaryotic E2Fs are conserved transcription factors playing crucial and antagonistic roles in several pathways related to cell division, DNA repair, and differentiation. In plants, these processes are strictly intermingled at the growing zone to produce postembryonic development in response to internal signals and environmental cues. Of the six AtE2F proteins found in Arabidopsis (Arabidopsis thaliana), only AtE2Fa and AtE2Fb have been clearly indicated as activators of E2F-responsive genes. AtE2Fa activity was shown to induce S phase and endoreduplication, whereas the function of AtE2Fb and the interrelationship between these two transcription factors was unclear. We have investigated the role played by the AtE2Fb gene during cell cycle and development performing in situ RNA hybridization, immunolocalization of the AtE2Fb protein in planta, and analysis of AtE2Fb promoter activity in transgenic plants. Overexpression of AtE2Fb in transgenic Arabidopsis plants led to striking modifications of the morphology of roots, cotyledons, and leaves that can be ascribed to stimulation of cell division. The accumulation of the AtE2Fb protein in these lines was paralleled by an increased expression of E2F-responsive G1/S and G2/M marker genes. These results suggest that AtE2Fa and AtE2Fb have specific expression patterns and play similar but distinct roles during cell cycle progression.
authors.affiliation: Department of Genetics and Microbiology, University of Pavia, 27100 Pavia, Italy.
authors.forename: Rosangela
authors.initials: R
authors.lastname: Sozzani
authors.forename: Caterina
authors.initials: C
authors.lastname: Maggio
authors.forename: Serena
authors.initials: S
authors.lastname: Varotto
authors.forename: Sabrina
authors.initials: S
authors.lastname: Canova
authors.forename: Catherine
authors.initials: C
authors.lastname: Bergounioux
authors.forename: Diego
authors.initials: D
authors.lastname: Albani
authors.forename: Rino
authors.initials: R
authors.lastname: Cella
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism* / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology*; D002460:Cell Line; D018548:Cotyledon / Q000166:cytology / Q000378:metabolism; D050684:E2F Transcription Factors / Q000378:metabolism* / Q000502:physiology; D005819:Genetic Markers; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D029681:Arabidopsis Proteins; D050684:E2F Transcription Factors; C496141:E2Fa protein, Arabidopsis; C506682:E2Fb protein, Arabidopsis; D005819:Genetic Markers