Sasai Kaori, Katayama Hiroshi, Stenoien David L, Fujii Satoshi, Honda Reiko, Kimura Masashi, Okano Yukio, Tatsuka Masaaki, Suzuki Fumio, Nigg Erich A, Earnshaw William C, Brinkley William R, Sen Subrata
Department of Molecular Pathology, Division of Pathology and Laboratory Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA.
Cell Motil Cytoskeleton. 2004 Dec;59(4):249-63. doi: 10.1002/cm.20039.
The function of Aurora-C kinase, a member of the Aurora kinase family identified in mammals, is currently unknown. We present evidence that Aurora-C, like Aurora-B kinase, is a chromosomal passenger protein localizing first to centromeres and then to the midzone of mitotic cells. Aurora-C transcript is expressed at a moderate level albeit about an order of magnitude lower than Aurora-B transcript in diploid human fibroblasts. The level of Aurora-C transcript is elevated in several human cancer cell types. Aurora-C and Aurora-B mRNA and protein expressions are maximally elevated during the G2/M phase but their expression profiles in synchronized cells reveal differential temporal regulation through the cell cycle with Aurora-C level peaking after that of Aurora-B during the later part of the M phase. Aurora-C, like Aurora-B, interacts with the inner centromere protein (INCENP) at the carboxyl terminal end spanning the conserved IN box domain. Competition binding assays and transfection experiments revealed that, compared with Aurora-C, Aurora-B has preferential binding affinity to INCENP and co-expression of the two in vivo interferes with INCENP binding, localization, and stability of these proteins. A kinase-dead mutant of Aurora-C had a dominant negative effect inducing multinucleation in a dose-dependent manner. siRNA mediated silencing of Aurora-C and Aurora-B also gave rise to multinucleated cells with the two kinases silenced at the same time displaying an additive effect. Finally, Aurora-C could rescue the Aurora-B silenced multinucleation phenotype, demonstrating that Aurora-C kinase function overlaps with and complements Aurora-B kinase function in mitosis.
极光激酶家族在哺乳动物中发现的成员极光-C激酶的功能目前尚不清楚。我们提供的证据表明，与极光-B激酶一样，极光-C是一种染色体乘客蛋白，首先定位于着丝粒，然后定位于有丝分裂细胞的中间区。在二倍体人成纤维细胞中，极光-C转录本以中等水平表达，尽管比极光-B转录本低约一个数量级。在几种人类癌细胞类型中，极光-C转录本的水平升高。极光-C和极光-B的mRNA和蛋白质表达在G2/M期达到最高水平，但它们在同步细胞中的表达谱显示，在整个细胞周期中存在不同的时间调控，极光-C水平在M期后期在极光-B之后达到峰值。与极光-B一样，极光-C在跨越保守IN盒结构域的羧基末端与着丝粒内蛋白（INCENP）相互作用。竞争结合试验和转染实验表明，与极光-C相比，极光-B对INCENP具有优先结合亲和力，两者在体内共表达会干扰INCENP的结合、定位和这些蛋白质的稳定性。极光-C的激酶失活突变体具有显性负效应，以剂量依赖的方式诱导多核形成。siRNA介导的极光-C和极光-B沉默也产生了多核细胞，同时沉默这两种激酶显示出累加效应。最后，极光-C可以挽救极光-B沉默的多核表型，表明极光-C激酶功能在有丝分裂中与极光-B激酶功能重叠并互补。
