Canudas Silvia, Houghtaling Benjamin R, Kim Ju Youn, Dynek Jasmin N, Chang William G, Smith Susan
Program in Molecular Pathogenesis and Department of Pathology, The Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, New York, NY 10016, USA.
EMBO J. 2007 Nov 28;26(23):4867-78. doi: 10.1038/sj.emboj.7601903. Epub 2007 Oct 25.
Previous studies in human cells indicate that sister telomeres have distinct requirements for their separation at mitosis. In cells depleted for tankyrase 1, a telomeric poly(ADP-ribose) polymerase, sister chromatid arms and centromeres separate normally, but telomeres remain associated and cells arrest in mitosis. Here, we use biochemical and genetic approaches to identify proteins that might mediate the persistent association at sister telomeres. We use immunoprecipitation analysis to show that the telomeric proteins, TRF1 (an acceptor of PARsylation by tankyrase 1) and TIN2 (a TRF1 binding partner) each bind to the SA1 ortholog of the cohesin Scc3 subunit. Sucrose gradient sedimentation shows that TRF1 cosediments with the SA1-cohesin complex. Depletion of the SA1 cohesin subunit or the telomeric proteins (TRF1 and TIN2) restores the normal resolution of sister telomeres in mitosis in tankyrase 1-depleted cells. Moreover, depletion of TRF1 and TIN2 or SA1 abrogates the requirement for tankyrase 1 in mitotic progression. Our studies indicate that sister telomere association in human cells is mediated by a novel association between a cohesin subunit and components of telomeric chromatin.
先前在人类细胞中的研究表明，姐妹端粒在有丝分裂时的分离有不同的要求。在缺乏端粒多聚（ADP-核糖）聚合酶端锚聚合酶1的细胞中，姐妹染色单体臂和着丝粒正常分离，但端粒仍保持关联，细胞停滞在有丝分裂期。在这里，我们使用生化和遗传学方法来鉴定可能介导姐妹端粒持续关联的蛋白质。我们通过免疫沉淀分析表明，端粒蛋白TRF1（端锚聚合酶1进行聚（ADP-核糖）基化修饰的受体）和TIN2（TRF1结合伴侣）各自与黏连蛋白Scc3亚基的SA1直系同源物结合。蔗糖梯度沉降显示TRF1与SA1-黏连蛋白复合物共沉降。缺乏SA1黏连蛋白亚基或端粒蛋白（TRF1和TIN2）可恢复端锚聚合酶1缺乏的细胞中有丝分裂时姐妹端粒的正常分离。此外，缺乏TRF1、TIN2或SA1消除了有丝分裂进程中端锚聚合酶1的需求。我们的研究表明，人类细胞中姐妹端粒的关联是由黏连蛋白亚基与端粒染色质成分之间的新型关联介导的。
