Arabidopsis RETINOBLASTOMA-RELATED PROTEIN 1 is involved in G1 phase cell cycle arrest caused by sucrose starvation.
Although sucrose availability is crucial for commitment to plant cell division during G1 phase by controlling the expression of D-type cyclins, it has remained unclear how these factors mediate entry into the cell cycle. Here we show that Arabidopsis RETINOBLASTOMA-RELATED PROTEIN 1 (AtRBR1) is involved in G1-phase cell cycle arrest caused by sucrose starvation. We generated estrogen-inducible AtRBR1 RNA interference (RNAi) Arabidopsis suspension MM2d cells, and found that downregulation of AtRBR1 leads to a higher frequency of arrest in G2 phase, instead of G1-phase arrest in the uninduced control, after sucrose starvation. Synchronization experiments confirmed that downregulation of AtRBR1 leads to a prolonged G2 phase and delayed activation of G2/M marker genes. Downregulation of AtRBR1 also stimulated the activation of E2F-regulated genes when these genes were repressed in the uninduced cells under the limited sucrose conditions. We conclude that AtRBR1 is a key effector for the ability of sucrose to modulate progression from G1 phase.
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0101, Japan.
Hiroto
H
Hirano
Hirofumi
H
Harashima
Atsuhiko
A
Shinmyo
Masami
M
Sekine
D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology; D016193:G1 Phase / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D016195:G2 Phase / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D034622:RNA Interference; D013395:Sucrose / Q000378:metabolism / Q000494:pharmacology*
D029681:Arabidopsis Proteins; D004967:Estrogens; C487568:RBR1 protein, Arabidopsis; D013395:Sucrose