Misexpression of the cyclin-dependent kinase inhibitor ICK1/KRP1 in single-celled Arabidopsis trichomes reduces endoreduplication and cell size and induces cell death.
A positive correlation between cell size and DNA content has been recognized in many plant cell types. Conversely, misexpression of a dominant-negative cyclin-dependent kinase (CDK) or CDK inhibitor proteins (ICK/KRPs) in Arabidopsis and tobacco leaves has revealed that cell growth can be uncoupled from cell cycle progression and DNA content. However, cell growth also appears to be controlled in a non-cell-autonomous manner by organ size, making it difficult in a ubiquitous expression assay to judge the cell-autonomous function of putative cell growth regulators. Here, we investigated the function of the CDK inhibitor ICK1/KRP1 on cell growth and differentiation independent of any compensatory influence of an organ context using Arabidopsis trichomes as a model system. By analyzing cell size with respect to DNA content, we dissected cell growth in a DNA-dependent and a DNA-independent process. We further found that ICK1/KRP1 misexpression interfered with differentiation and induced cell death, linking cell cycle progression, differentiation, and cell death in plants. The function of ICK1/KRP1 in planta was found to be dependent on a C-terminal domain and regulated negatively by an N-terminal domain. Finally, we identified CDKA;1 and a D-type cyclin as possible targets of ICK1/KRP1 expression in vivo.
Schnittger
Arp
A
Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany. schnitt@mpiz-koeln.mpg.de
Weinl
Christina
C
Bouyer
Daniel
D
Schöbinger
Ulrike
U
Hülskamp
Martin
M
D017209:Apoptosis / Q000235:genetics*; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D048429:Cell Size / Q000235:genetics; D022081:Cell Surface Extensions / Q000235:genetics* / Q000648:ultrastructure; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D056741:Cyclin D; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication / Q000235:genetics*; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008855:Microscopy, Electron, Scanning; D010641:Phenotype; D030821:Plants, Genetically Modified
D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056741:Cyclin D; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D016213:Cyclins; D018744:DNA, Plant; C114853:ICK1 protein, Arabidopsis; C434472:CDKA1 protein, Arabidopsis; D018844:Cyclin-Dependent Kinases