Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205.
Mol Biol Cell. 2013 Nov;24(22):3483-95. doi: 10.1091/mbc.E13-05-0230. Epub 2013 Sep 18.
Sumoylation of centromere, kinetochore, and other mitotic chromosome-associated proteins is essential for chromosome segregation. The mechanisms regulating spatial and temporal sumoylation of proteins in mitosis, however, are not well understood. Here we show that the small ubiquitin-related modifier (SUMO)-specific isopeptidases SENP1 and SENP2 are targeted to kinetochores in mitosis. SENP2 targeting occurs through a mechanism dependent on the Nup107-160 subcomplex of the nuclear pore complex and is modulated through interactions with karyopherin α. Overexpression of SENP2, but not other SUMO-specific isopeptidases, causes a defect in chromosome congression that depends on its precise kinetochore targeting. By altering SENP1 kinetochore associations, however, this effect on chromosome congression could be phenocopied. In contrast, RNA interference-mediated knockdown of SENP1 delays sister chromatid separation at metaphase, whereas SENP2 knockdown produces no detectable phenotypes. Our findings indicate that chromosome segregation depends on precise spatial and temporal control of sumoylation in mitosis and that SENP1 and SENP2 are important mediators of this control.
着丝粒、动粒和其他有丝分裂染色体相关蛋白的 SUMO 化对于染色体分离是必不可少的。然而，调节有丝分裂中蛋白质时空 SUMO 化的机制尚不清楚。在这里，我们表明，小泛素相关修饰酶（SUMO）特异性肽酶 SENP1 和 SENP2 在有丝分裂中被靶向到动粒。SENP2 的靶向发生是通过一种依赖于核孔复合物的 Nup107-160 亚复合物的机制，并通过与载体蛋白 α 的相互作用进行调节。SENP2 的过表达而非其他 SUMO 特异性肽酶的过表达会导致染色体向心性聚集缺陷，这取决于其精确的动粒靶向。然而，通过改变 SENP1 动粒的关联，可以模拟对染色体向心性聚集的这种影响。相比之下，RNA 干扰介导的 SENP1 敲低会延迟中期姐妹染色单体的分离，而 SENP2 敲低则不会产生可检测到的表型。我们的研究结果表明，染色体分离依赖于有丝分裂中 SUMO 化的精确时空控制，而 SENP1 和 SENP2 是这种控制的重要介质。
