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- Title
Inhibition of Proteasome by MG-132 Treatment Causes Extra Phragmoplast Formation and Cortical Microtubule Disorganization during M/G1 Transition in Synchronized Tobacco Cells.
- Authors
Oka, Masayoshi; Yanagawa, Yuki; Asada, Tetsuhiro; Yoneda, Arata; Hasezawa, Seiichiro; Sato, Takahide; Nakagawa, Hiroki
- Abstract
The 26S proteasome plays essential roles in cell cycle progression in various types of cell. We previously reported that the inhibition of 26S proteasome activities by a proteasome inhibitor, MG-132, exclusively caused cell cycle arrest in synchronized tobacco BY-2 cells. Here we report a further observation of 26S proteasome involvement during M/G1 transition utilizing a transgenetic BY-2 cell line that stably expresses a GFP–α-tubulin fusion protein (BY-GT16). Interestingly, MG-132 treatment caused the arrest of cell cycle progression prior to entering the G1 phase. Indeed, phragmoplast-like structures were formed and cortical microtubules were not organized after the collapse of the original phragmoplasts. Additionally, actin microfilaments showed irregular rearrangements when further incubated with MG-132 and as the phragmoplast-like structures developed. Since these phragmoplast-like structures had a similar configuration and ability to form cell plates to that of the original phragmoplasts, we designated these phragmoplast-like structures as extra phragmoplasts. Furthermore, we showed that a tobacco kinesin-related polypeptide of 125 kDa (TKRP125) localized in the extra phragmoplasts and that its protein level remained unchanged during MG-132 treatment. We propose that TKRP125 might be one of the possible targets of the ubiquitin-proteasome degradation pathway during M/G1 transition.
- Subjects
CELL cycle regulation; PLANT cell cycle; TOBACCO; TRANSGENE expression; CELL lines; MICROTUBULES; ACTIN; POLYPEPTIDES
- Publication
Plant & Cell Physiology, 2004, Vol 45, Issue 11, p1623
- ISSN
0032-0781
- Publication type
Article
- DOI
10.1093/pcp/pch183