Ubiquitin Conjugating Enzyme E2Q2 (UBE2Q2)

UBE2Q2 can covalently bind ubiquitin on the active site cysteine within the UBC domain. Inhibition of UBE2Q2 in HeLa cells caused an early mitotic arrest and increased cytotoxicity when the cells were treated with microtubule-inhibiting agents (MIAs). Changes in cell cycle progression and viability were not observed in the absence of MIA treatment, indicating that UBE2Q2 is involved in the response to MIAs rather than performing a more general function in mitosis. Inhibition of the UBE2Q2 protein caused cells to undergo a prolonged prophase arrest, suggesting that UBE2Q2 normally functions to antagonize an early mitotic checkpoint. Inhibition of UBE2Q2 also sensitized cells to the cytotoxic effects of MIAs through caspase-mediated apoptosis that was correlated with PARP1 cleavage.