Chen Helen, Mohan Pooja, Jiang Jihong, Nemirovsky Oksana, He Daniel, Fleisch Markus C, Niederacher Dieter, Pilarski Linda M, Lim C James, Maxwell Christopher A
Department of Pediatrics; Child and Family Research Institute; University of British Columbia; Vancouver, British Columbia, Canada.
Department of Gynaecology and Obstetrics; University Hospital Düsseldorf; Heinrich-Heine University; Düsseldorf, Germany.
Cell Cycle. 2014;13(14):2248-61. doi: 10.4161/cc.29270. Epub 2014 May 29.
Construction of a mitotic spindle requires biochemical pathways to assemble spindle microtubules and structural proteins to organize these microtubules into a bipolar array. Through a complex with dynein, the receptor for hyaluronan-mediated motility (RHAMM) cross-links mitotic microtubules to provide structural support, maintain spindle integrity, and correctly orient the mitotic spindle. Here, we locate RHAMM to sites of microtubule assembly at centrosomes and non-centrosome sites near kinetochores and demonstrate that RHAMM is required for the activation of Aurora kinase A. Silencing of RHAMM delays the kinetics of spindle assembly, mislocalizes targeting protein for XKlp2 (TPX2), and attenuates the localized activation of Aurora kinase A with a consequent reduction in mitotic spindle length. The RHAMM-TPX2 complex requires a C-terminal basic leucine zipper in RHAMM and a domain that includes the nuclear localization signal in TPX2. Together, our findings identify RHAMM as a critical regulator for Aurora kinase A signaling and suggest that RHAMM ensures bipolar spindle assembly and mitotic progression through the integration of biochemical and structural pathways.
有丝分裂纺锤体的构建需要生化途径来组装纺锤体微管，以及结构蛋白将这些微管组织成双极阵列。通过与动力蛋白形成复合物，透明质酸介导的运动受体（RHAMM）交联有丝分裂微管，以提供结构支持、维持纺锤体完整性并正确定向有丝分裂纺锤体。在这里，我们将RHAMM定位到中心体以及靠近动粒的非中心体部位的微管组装位点，并证明RHAMM是极光激酶A激活所必需的。沉默RHAMM会延迟纺锤体组装的动力学，使XKlp2靶向蛋白（TPX2）定位错误，并减弱极光激酶A的局部激活，从而导致有丝分裂纺锤体长度缩短。RHAMM-TPX2复合物需要RHAMM中的C端碱性亮氨酸拉链以及TPX2中包含核定位信号的结构域。总之，我们的研究结果确定RHAMM是极光激酶A信号传导的关键调节因子，并表明RHAMM通过整合生化和结构途径确保双极纺锤体组装和有丝分裂进程。
