title: Cullin 4-ring finger-ligase plays a key role in the control of endoreplication cycles in Arabidopsis trichomes.
abstract: One of the predominant cell-cycle programs found in mature tissues is endoreplication, also known as endoreduplication, that leads to cellular polyploidy. A key question for the understanding of endoreplication cycles is how oscillating levels of cyclin-dependent kinase activity are generated that control repeated rounds of DNA replication. The APC/C performs a pivotal function in the mitotic cell cycle by promoting anaphase and paving the road for a new round of DNA replication. However, using marker lines and plants in which APC/C components are knocked down, we show here that outgrowing and endoreplicating Arabidopsis leaf hairs display no or very little APC/C activity. Instead we find that RBX1-containing Cullin-RING E3 ubiquitin-Ligases (CRLs) are of central importance for the progression through endoreplication cycles; in particular, we have identified CULLIN4 as a major regulator of endoreplication in Arabidopsis trichomes. We have incorporated our findings into a bio-mathematical simulation presenting a robust two-step model of endoreplication control with one type of cyclin-dependent kinase inhibitor function for entry and a CRL-dependent oscillation of cyclin-dependent kinase activity via degradation of a second type of CDK inhibitor during endoreplication cycles.
authors.affiliation: Department of Botany III, Unigruppe at the Max-Planck-Institute for Plant Breeding Research, Max-Delbrück-Laboratorium, University of Cologne, 50829 Cologne, Germany.
authors.forename: Farshad
authors.initials: F
authors.lastname: Roodbarkelari
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bramsiepe
authors.forename: Christina
authors.initials: C
authors.lastname: Weinl
authors.forename: Sebastian
authors.initials: S
authors.lastname: Marquardt
authors.forename: Béla
authors.initials: B
authors.lastname: Novák
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Jakoby
authors.forename: Esther
authors.initials: E
authors.lastname: Lechner
authors.forename: Pascal
authors.initials: P
authors.lastname: Genschik
authors.forename: Arp
authors.initials: A
authors.lastname: Schnittger
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D018744:DNA, Plant / Q000096:biosynthesis / Q000235:genetics; D017343:Genes, Plant; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D009154:Mutation; D018514:Plant Structures / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D011123:Polyploidy; D034622:RNA Interference
chemical_list: D029681:Arabidopsis Proteins; C514806:CULLIN4 protein, Arabidopsis; D002352:Carrier Proteins; D044842:Cullin Proteins; D018744:DNA, Plant; C507151:RBX1 protein, Arabidopsis