title: Arabidopsis E2Fc functions in cell division and is degraded by the ubiquitin-SCF(AtSKP2) pathway in response to light.
abstract: Selective ubiquitin-mediated proteolysis through the cell cycle controls the availability, and therefore the activity, of several cell proliferation proteins. E2F transcription factors play distinct roles in both proliferating and differentiated cells by regulating gene expression. Here, we report that Arabidopsis AtE2Fc is regulated by a balance between gene expression and ubiquitin-proteasome proteolysis. AtE2Fc degradation implicates the function of the E3 ubiquitin-ligase Skp1, Cullin, F-box (SCF(AtSKP2)) complex and seems to be dependent on cyclin-dependent kinase phosphorylation. In addition, we found that AtE2Fc degradation is triggered by light stimulation of dark-grown seedlings. Interestingly, the auxin response mutant axr1-12, in which RUB1 modification of the SCF component CUL1 is impaired, shows increased AtE2Fc protein levels, suggesting a dysfunction in the control of AtE2Fc stability. Likewise, overexpression of a stable form of the AtE2Fc protein negatively affects cell division and increases cell size. These effects are mediated, at least in part, by downregulating the cell cycle gene AtCDC6. The negative role of AtE2Fc in gene expression is further supported by the fact that AtE2Fc interacts with plant retinoblastoma-related protein, suggesting that AtE2Fc might form part of a repressor complex. We propose that AtE2Fc might play a role in cell division and during the transition from skotomorphogenesis to photomorphogenesis.
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: del Pozo
authors.forename: Maria Beatrice
authors.initials: MB
authors.lastname: Boniotti
authors.forename: Crisanto
authors.initials: C
authors.lastname: Gutierrez
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D044842:Cullin Proteins; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D050684:E2F Transcription Factors; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D008027:Light; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D010766:Phosphorylation; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D014452:Ubiquitins
chemical_list: D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; C100318:Cullin 1; D044842:Cullin Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D012333:RNA, Messenger; C513170:RUB1 protein, Arabidopsis; D014157:Transcription Factors; D014452:Ubiquitins; D044843:SKP Cullin F-Box Protein Ligases; D018844:Cyclin-Dependent Kinases; D005966:Glucuronidase; D010453:Peptide Synthases