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The auto-ubiquitylation of E3 ubiquitin-protein ligase Chfr at G 2 phase is required for accumulation of polo-like kinase 1 and mitotic entry in mammalian cells
- Title
- The auto-ubiquitylation of E3 ubiquitin-protein ligase Chfr at G 2 phase is required for accumulation of polo-like kinase 1 and mitotic entry in mammalian cells
- Authors
- Kim J.-S.; Park Y.-Y.; Park S.-Y.; Cho H.; Kang D.
- Ewha Authors
- 강동민
- SCOPUS Author ID
- 강동민
- Issue Date
- 2011
- Journal Title
- Journal of Biological Chemistry
- ISSN
- 0021-9258
- Citation
- Journal of Biological Chemistry vol. 286, no. 35, pp. 30615 - 30623
- Indexed
- SCI; SCIE; SCOPUS
- Document Type
- Article
- Abstract
- The E3 ubiquitin-protein ligase Chfr is a mitotic stress checkpoint protein that delays mitotic entry in response to microtubule damage; however, the molecular mechanism by which Chfr accomplishes this remains elusive. Here, we show that Chfr levels are elevated in response to microtubule-damaging stress. Moreover, G 2/M transition is associated with cell cycle-dependent turnover of Chfr accompanied by high autoubiquitylation activity, suggesting that regulation of Chfr levels and auto-ubiquitylation activity are functionally significant. To test this, we generated Chfr mutants Chfr-K2A and Chfr-K5A in which putative lysine target sites of auto-ubiquitylation were replaced with alanine. Chfr-K2A did not undergo cell cycle-dependent degradation, and its levels remained high during G 2/M phase. The elevated levels of Chfr-K2A caused a significant reduction in phosphohistone H3 levels and cyclinB1/Cdk1 kinase activities, leading to mitotic entry delay. Notably, polo-like kinase 1 levels at G 2 phase, but not at S phase, were ∼2-3-fold lower in cells expressing Chfr-K2A than in wild-type Chfr-expressing cells. Consistent with this, ubiquitylation of Plk1 at G 2 phase was accelerated in Chfr-K2A-expressing cells. In contrast, Aurora A levels remained constant, indicating that Plk1 is a major target of Chfr in controlling the timing of mitotic entry. Indeed, overexpression of Plk1 in Chfr-K2A-expressing cells restored cyclin B1/Cdk1 kinase activity and promoted mitotic entry. Collectively, these data indicate that Chfr auto-ubiquitylation is required to allow Plk1 to accumulate to levels necessary for activation of cyclin B1/Cdk1 kinase and mitotic entry. Our results provide the first evidence that Chfr auto-ubiquitylation and degradation are important for the G 2/M transition.
- DOI
- 10.1074/jbc.M111.231803
- Appears in Collections:
- 자연과학대학 > 생명과학전공 > Journal papers
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