Letter abstract


Nature Cell Biology 11, 1363 - 1369 (2009)
Published online: 11 October 2009 | doi:10.1038/ncb1983

UBE2S elongates ubiquitin chains on APC/C substrates to promote mitotic exit

Mathew J. Garnett1,3,4, Jörg Mansfeld2,3, Colin Godwin1, Takahiro Matsusaka2, Jiahua Wu1, Paul Russell1, Jonathon Pines2 & Ashok R. Venkitaraman1,4

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The anaphase-promoting complex (APC/C), a ubiquitin ligase, is the target of the spindle-assembly checkpoint (SAC), and it ubiquitylates protein substrates whose degradation regulates progress through mitosis1, 2, 3. The identity of the ubiquitin-conjugating (E2) enzymes that work with the APC/C is unclear. In an RNA interference (RNAi) screen for factors that modify release from drug-induced SAC activation, we identified the E2 enzyme UBE2S as an APC/C auxiliary factor that promotes mitotic exit. UBE2S is dispensable in a normal mitosis, but its depletion prolongs drug-induced mitotic arrest and suppresses mitotic slippage. In vitro, UBE2S elongates ubiquitin chains initiated by the E2 enzymes UBCH10 and UBCH5, enhancing the degradation of APC/C substrates by the proteasome. Indeed, following release from SAC-induced mitotic arrest, UBE2S-depleted cells neither degrade crucial APC/C substrates, nor silence this checkpoint, whereas bypassing the SAC through BUBR1 depletion or Aurora-B inhibition negates the requirement for UBE2S. Thus, UBE2S functions with the APC/C in a two-step mechanism to control substrate ubiquitylation that is essential for mitotic exit after prolonged SAC activation, providing a new model for APC/C function in human cells.

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  1. University of Cambridge, Department of Oncology and The Medical Research Council Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge, CB2 OXZ, UK.
  2. Wellcome/Cancer Research UK Gurdon Institute and Department of Zoology, Tennis Court Road, Cambridge, CB2 1QN, UK.
  3. These authors contributed equally to this work.
  4. Correspondence should be addressed to M.J.G or A.R.V.e-mail: arv22@cam.ac.uk


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