Regulation of mitotic exit by the RNF8 ubiquitin ligase.
RNF8 is a ubiquitin ligase with a FHA domain near its N terminus, and a RING-finger domain at its C terminus, through which it recruits several ubiquitin-conjugating enzymes. In metazoans, only the mitotic checkpoint regulator CHFR shares this domain architecture. Here we show that RNF8 is a nuclear protein that follows a cell-cycle-dependent turnover, reaching its highest levels in mitosis, followed by a strong decline in late mitotic stages. Overexpression of RNF8 caused a delay in cytokinesis and the frequent appearance of aberrant mitotic figures. These effects were dependent on the ubiquitin ligase activity of RNF8, since they were significantly attenuated when a RING-finger mutant, inactive as an E3, was overexpressed. Depletion of RNF8 also caused a delay in the exit from the mitotic arrest induced by nocodazole, associated with a reduced turnover of the APC/C substrate cyclin B1. These observations suggest that RNF8 regulates the rate of exit from mitosis and cytokinesis.
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Department of Molecular and Cellular Biology, Instituto de Biología Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.
Guerra-Rebollo
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Thomson
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D002467:Cell Nucleus / Q000201:enzymology / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
D004268:DNA-Binding Proteins; C486521:RNF8 protein, human; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases