cells. UFBs positive for PICH only or for BLM only or for both PICH and BLM were scored in three independent experiments including a total of 129 cells transfected with control siRNAs and 129 cells transfected with PICH siRNAs. (TIF) Acknowledgments We thank L. Aragon for invaluable discussions, A. Carreira, S. Lambert and O. Gavet for helpful discussions and useful comments on the References 1. Carroll CW, Straight AF (2006) Centromere formation: from epigenetics to self- assembly. Trends Cell Biol 16: 70–78. 2. Cleveland DW, Mao Y, Sullivan KF (2003) Centromeres and kinetochores: from epigenetics to mitotic checkpoint signaling. Cell 112: 407–421. 3. Yuen KW, Montpetit B, Hieter P (2005) The kinetochore and cancer: what’s the connection? Curr Opin Cell Biol 17: 576–582. 4. Baumann C, Korner R, Hofmann K, Nigg EA (2007) PICH, a centromere- associated SNF2 family ATPase, is regulated by Plk1 and required for the spindle checkpoint. Cell 128: 101–114. 5. Chan KL, North PS, Hickson ID (2007) BLM is required for faithful chromosome segregation and its localization defines a class of ultrafine anaphase bridges. EMBO J 26: 3397–3409. 6. Wang LH, Schwarzbraun T, Speicher MR, Nigg EA (2008) Persistence of DNA threads in human anaphase cells suggests late completion of sister chromatid decatenation. Chromosoma 117: 123–135. 7. Wang LH, Mayer B, Stemmann O, Nigg EA (2010) Centromere DNA decatenation depends on cohesin removal and is required for mammalian cell division. J Cell Sci 123: 806–813. 8. Amor-Gueret M (2006) Bloom syndrome, genomic instability and cancer: the SOS-like hypothesis. Cancer Lett 236: 1–12. 9. Ke Y, Huh JW, Warrington R, Li B, Wu N, et al. (2011) PICH and BLM limit histone association with anaphase centromeric DNA threads and promote their resolution. EMBO J 30: 3309–3321. 10. Chabosseau P, Buhagiar-Labarchede G, Onclercq-Delic R, Lambert S, Debatisse M, et al. (2011) Pyrimidine pool imbalance induced by BLM helicase deficiency contributes to genetic instability in Bloom syndrome. Nat Commun 2: 368. 11. Yankiwski V, Marciniak RA, Guarente L, Neff NF (2000) Nuclear structure in normal and Bloom syndrome cells. Proc Natl Acad Sci U S A 97: 5214–5219. 12. Pines J, Hunter T (1991) Human cyclins A and B1 are differentially located in the cell and undergo cell cycle-dependent nuclear transport. J Cell Biol 115: 1–17. 13. Guo RB, Rigolet P, Ren H, Zhang B, Zhang XD, et al. (2007) Structural and functional analyses of disease-causing missense mutations in Bloom syndrome protein. Nucleic Acids Res 35: 6297–6310. 14. Batram C, Baddeley D, Kreth G, Cremer C (2008) High precision size measurement of centromere 8 and the 8q24/c-myc gene region in metaphase and interphase human fibroblasts indicate differential condensation. J Struct Biol 164: 293–303. 15. Ke Y, Huh JW, Warrington R, Li B, Wu N, et al. (2011) PICH and BLM limit histone association with anaphase centromeric DNA threads and promote their resolution. EMBO J 30: 3309–3021. 16. Diaz-Martinez LA, Gimenez-Abian JF, Clarke DJ (2008) Chromosome cohesion - rings, knots, orcs and fellowship. J Cell Sci 121: 2107–2114. 17. Chan KL, Hickson ID (2011) New insights into the formation and resolution of ultra-fine anaphase bridges. Semin Cell Dev Biol 22: 906–912. BLM and PICH in Centromere Disjunction manuscript, S. Augui and O. Philipot for advice concerning FISH and ChIP and T. Verly for graphical support. Author Contributions Conceived and designed the experiments: SR MAG. Performed the experiments: SR GBL IH ROD SG LMJ. Analyzed the data: SR FPC CJ MAG. Wrote the paper: SR MAG. 18. Sano K, Miyaji-Yamaguchi M, Tsutsui KM, Tsutsui K (2008) Topoisomerase IIbeta activates a subset of neuronal genes that are repressed in AT-rich genomic environment. PLoS One 3: e4103. 19. Baxter J, Sen N, Martinez VL, De Carandini ME, Schvartzman JB, et al. (2011) Positive supercoiling of mitotic DNA drives decatenation by topoisomerase II in eukaryotes. Science 331: 1328–1332. 20. Eladad S, Ye TZ, Hu P, Leversha M, Beresten S, et al. (2005) Intra-nuclear trafficking of the BLM helicase to DNA damage-induced foci is regulated by SUMO modification. Hum Mol Genet 14: 1351–1365. 21. Lahkim Bennani-Belhaj K, Rouzeau S, Buhagiar-Labarchede G, Chabosseau P, Onclercq-Delic R, et al. (2010) The Bloom syndrome protein limits the lethality associated with RAD51 deficiency. Mol Cancer Res 8: 385–394. 22. Hubner NC, Wang LH, Kaulich M, Descombes P, Poser I, et al. (2010) Re- examination of siRNA specificity questions role of PICH and Tao1 in the spindle checkpoint and identifies Mad2 as a sensitive target for small RNAs. Chromosoma 119: 149–165. 23. Ababou M, Dumaire V, Lecluse Y, Amor-Gueret M (2002) Cleavage of BLM and sensitivity of Bloom’s syndrome cells to hydroxurea and UV-C radiation. Cell Cycle 1: 262–266. 24. Bustin SA, Benes V, Garson JA, Hellemans J, Huggett J, et al. (2009) The MIQE guidelines: minimum information for publication of quantitative real-time PCR experiments. Clin Chem 55: 611–622. 25. Vandesompele J, De Preter K, Pattyn F, Poppe B, Van Roy N, et al. (2002) Accurate normalization of real-time quantitative RT-PCR data by geometric averaging of multiple internal control genes. Genome Biol 3: RESEARCH0034. 26. Viegas MH, Gehring NH, Breit S, Hentze MW, Kulozik AE (2007) The abundance of RNPS1, a protein component of the exon junction complex, can determine the variability in efficiency of the Nonsense Mediated Decay pathway. Nucleic Acids Res 35: 4542–4551. 27. Eot-Houllier G, Fulcrand G, Watanabe Y, Magnaghi-Jaulin L, Jaulin C (2008) Histone deacetylase 3 is required for centromeric H3K4 deacetylation and sister chromatid cohesion. Genes Dev 22: 2639–2644. 28. Savino TM, Gebrane-Younes J, De Mey J, Sibarita JB, Hernandez-Verdun D (2001) Nucleolar assembly of the rRNA processing machinery in living cells. J Cell Biol 153: 1097–1110. 29. Agostinho M, Rino J, Braga J, Ferreira F, Steffensen S, et al. (2004) Human topoisomerase IIalpha: targeting to subchromosomal sites of activity during interphase and mitosis. Mol Biol Cell 15: 2388–2400. 30. Bolte S, Cordelieres FP (2006) A guided tour into subcellular colocalization analysis in light microscopy. J Microsc 224: 213–232. 31. Warburton PE, Greig GM, Haaf T, Willard HF (1991) PCR amplification of chromosome-specific alpha satellite DNA: definition of centromeric STS markers and polymorphic analysis. Genomics 11: 324–333. 32. Jolly C, Metz A, Govin J, Vigneron M, Turner BM, et al. (2004) Stress-induced transcription of satellite III repeats. J Cell Biol 164: 25–33. PLoS ONE | www.plosone.org 12 April 2012 | Volume 7 | Issue 4 | e33905