Cullin 4-ring finger-ligase plays a key role in the control of endoreplication cycles in Arabidopsis trichomes.
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.
Roodbarkelari
Farshad
F
Department of Botany III, Unigruppe at the Max-Planck-Institute for Plant Breeding Research, Max-Delbrück-Laboratorium, University of Cologne, 50829 Cologne, Germany.
Bramsiepe
Jonathan
J
Weinl
Christina
C
Marquardt
Sebastian
S
Novák
Béla
B
Jakoby
Marc J
MJ
Lechner
Esther
E
Genschik
Pascal
P
Schnittger
Arp
A
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
D029681:Arabidopsis Proteins; C514806:CULLIN4 protein, Arabidopsis; D002352:Carrier Proteins; D044842:Cullin Proteins; D018744:DNA, Plant; C507151:RBX1 protein, Arabidopsis