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Arsenite-induced Cdc25C degradation is through the KEN-box and ubiquitin-proteasome pathway
Fei Chen1, Zhuo Zhang, Jacquelyn Bower
1Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA. lfd3@cdc.gov
Abstract:
Arsenite is a known human carcinogen that induces tumorigenesis through either a genotoxic or an epigenetic mechanism. In this study, the effect of arsenite on cell cycle regulation and the mechanisms that contribute to this effect were investigated. Treatment of the cells with arsenite suppressed cell proliferation and reduced cell viability in a dose- or time-dependent manner. Analysis of cell cycle profile and cell cycle regulatory proteins indicated that arsenite arrested the cell cycle at G(2)/M phase, partially through induction of cell division cycle 25 (Cdc25) isoform C (Cdc25C) degradation via ubiquitin-proteasome pathways. Mutation of the putative KEN box within the region 151 to 157 of human Cdc25C or treatment of the cells with a peptide competitor encompassing the KEN box partially inhibited arsenite-induced ubiquitination of Cdc25C. Thus, these results indicate that the regulated ubiquitination of Cdc25C may be involved in the arsenite-induced proteolytic down-regulation of Cdc25C activity in the G(2)/M phase of the cell cycle and suggest a link between cell cycle and the carcinogenic effects of arsenite.
Insights
Arsenite, a carcinogen, halts cell cycle progression at G(2)/M by degrading Cdc25C via the ubiquitin-proteasome pathway. This implicates cell cycle regulation in arsenite
Area of Science:
- Toxicology
- Cell Biology
- Molecular Biology
Background:
- Arsenite is a known human carcinogen.
- Carcinogenesis can occur via genotoxic or epigenetic mechanisms.
- Cell cycle regulation is crucial for preventing uncontrolled cell proliferation.
Purpose of the Study:
- To investigate the effects of arsenite on cell cycle regulation.
- To elucidate the molecular mechanisms underlying arsenite-induced cell cycle arrest.
- To determine the role of Cdc25C degradation in arsenite's carcinogenic pathway.
Main Methods:
- Cell proliferation and viability assays.
- Cell cycle analysis using flow cytometry.
- Western blotting to assess cell cycle regulatory proteins.
- Ubiquitination assays and site-directed mutagenesis of Cdc25C.
Main Results:
- Arsenite treatment suppressed cell proliferation and reduced cell viability.
- Arsenite induced cell cycle arrest at the G(2)/M phase.
- Arsenite promoted the degradation of Cdc25C through the ubiquitin-proteasome pathway.
- Mutating the KEN box of Cdc25C or using a peptide competitor partially inhibited arsenite-induced ubiquitination.
Conclusions:
- Regulated ubiquitination of Cdc25C is involved in arsenite-induced proteolytic down-regulation.
- Cdc25C activity modulation in G(2)/M phase is a key mechanism in arsenite's effects.
- This study suggests a link between cell cycle disruption and arsenite's carcinogenic properties.