Centromeric footprints preserve telomere integrity in ALT cancers

Cell Lines U2OS (ATCC; HTB-96), Saos-2 (ATCC; HTB-85) and HOS (ATCC; CRL-1543) cell lines were obtained from ATCC. The HeLa (LT, long telomere) cell line was validated using short-tandem-repeat profiling by ATCC’s cell line authentication services. The LM216J/T cells (described initially by J. P. Murnane) were provided by R. Greenberg. U2OS cells with a doxycycline-inducible ATRX allele were provided by D. Clynes 26 . SV40 large T-antigen immortalized IMR90 control and ATRX- KO ALT IMR90 cells were previously described and provided by H. Zheng and J. Paik 8 . U2OS cells stably expressing SNAP-tagged CENP-A were provided by G. Almouzni 13 , 29 . All of the cell lines were cultured in GlutaMax-DMEM supplemented with 10% bovine growth serum or fetal calf serum, non-essential amino acids and penicillin–streptomycin under 20% O 2 and 7.5% CO 2 at 37 °C. Cell lines were routinely tested for mycoplasma contamination. Plasmids Y. Dalal previously described and provided the GFP-tagged HJURP WT plasmid 51 . The GFP-tagged HJURP deletion mutants, Δ1-80aa and ΔTLTY box 42 , were generated as variants of this plasmid in this study. D. R. Foltz provided GFP-tagged Mis18BP1 (ref. 52 ) and YFP-H3 CATD (ref. 30 ). pBabe-SNAP-CENP-A-HA were previously described and provided by L. Jansen 13 . Flag-tagged TRF1-FokI WT and D450A plasmids were gifts from R. Greenberg 37 , 38 . pINDUCER dCas9-TET1-CD plasmids 53 were gifts from D. Huangfu (Addgene, 101920 and 101921). …