title: Light-dependent regulation of DEL1 is determined by the antagonistic action of E2Fb and E2Fc.
abstract: Endoreduplication represents a variation on the cell cycle in which multiple rounds of DNA replication occur without subsequent chromosome separation and cytokinesis, thereby increasing the cellular DNA content. It is known that the DNA ploidy level of cells is controlled by external stimuli such as light; however, limited knowledge is available on how environmental signals regulate the endoreduplication cycle at the molecular level. Previously, we had demonstrated that the conversion from a mitotic cell cycle into an endoreduplication cycle is controlled by the atypical E2F transcription factor, DP-E2F-LIKE1 (DEL1), that represses the endocycle onset. Here, the Arabidopsis (Arabidopsis thaliana) DEL1 gene was identified as a transcriptional target of the classical E2Fb and E2Fc transcription factors that antagonistically control its transcript levels through competition for a single E2F cis-acting binding site. In accordance with the reported opposite effects of light on the protein levels of E2Fb and E2Fc, DEL1 transcription depended on the light regime. Strikingly, modified DEL1 expression levels uncoupled the link between light and endoreduplication in hypocotyls, implying that DEL1 acts as a regulatory connection between endocycle control and the photomorphogenic response.
authors: Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium.
authors: Barbara
authors: B
authors: Berckmans
authors: Tim
authors: T
authors: Lammens
authors: Hilde
authors: H
authors: Van Den Daele
authors: Zoltan
authors: Z
authors: Magyar
authors: Laszlo
authors: L
authors: Bögre
authors: Lieven
authors: L
authors: De Veylder
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D001483:Base Sequence; D050684:E2F Transcription Factors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D018546:Hypocotyl / Q000235:genetics / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D030821:Plants, Genetically Modified; D011003:Ploidies; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000528:radiation effects; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C500416:DEL1 protein, Arabidopsis; D050684:E2F Transcription Factors; C514752:E2FC protein, Arabidopsis; C506682:E2Fb protein, Arabidopsis; D014157:Transcription Factors; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases