Telomerase-negative cancer cells maintain their telomeres through the alternative lengthening of telomeres (ALT) pathway1,2,3. Although a growing body of evidence demonstrates that the ALT mechanism is a post-replicative telomere recombination process, molecular details of this pathway are largely unknown. Here we demonstrate that MUS81, a DNA structure specific recombination endonuclease, has a key role in the maintenance of telomeres in human ALT cells. We find that MUS81 specifically localizes to ALT-associated promyelocytic leukaemia (PML) nuclear bodies (APBs) and associates with telomeric DNA in ALT cells, which is enriched during the G2 phase of the cell cycle. Depletion of MUS81 results in the reduction of ALT-specific telomere recombination and leads to proliferation arrest of ALT cells. In addition, the endonuclease activity of MUS81 is required for recombination-based ALT cell survival, and the interaction of MUS81 with the telomeric repeat-binding factor TRF2 regulates this enzymatic activity, thereby maintaining telomere recombination. Thus, our results suggest that MUS81 is involved in the maintenance of ALT cell survival at least in part by homologous recombination of telomeres.
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We thank R. R. Reddel for ALT cells, and C. H. McGowan for wild-type and mutant MUS81 constructs, the MUS81 antibody and Mus81 +/+ and Mus81−/− MEFs. We thank I. Hickson and J. Roti Roti for proof-reading. This work is supported in part by grants from Concern Foundation to Q.Y. and NIH CA10445/CA123232 to T.K.P. This research was also supported in part by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research.
The authors declare no competing financial interests.
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Zeng, S., Xiang, T., Pandita, T. et al. Telomere recombination requires the MUS81 endonuclease. Nat Cell Biol 11, 616–623 (2009). https://doi.org/10.1038/ncb1867
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