Wu Guikai, Lin Yi-Tzu, Wei Randy, Chen Yumay, Shan Zhiyin, Lee Wen-Hwa
Department of Biological Chemistry, School of Medicine, University of California, Irvine, Irvine, CA 92697-4037, USA.
Mol Cell Biol. 2008 Jun;28(11):3652-62. doi: 10.1128/MCB.01923-07. Epub 2008 Mar 24.
Spindle integrity is critical for efficient mitotic progression and accurate chromosome segregation. Deregulation of spindles often leads to structural and functional aberrations, ultimately promoting segregation errors and aneuploidy, a hallmark of most human cancers. Here we report the characterization of a previously identified human sarcoma antigen (gene located at 19p13.11), Hice1, an evolutionarily nonconserved 46-kDa coiled-coil protein. Hice1 shows distinct cytoplasmic localization and associates with interphase centrosomes and mitotic spindles, preferentially at the spindle pole vicinity. Depletion of Hice1 by RNA interference resulted in abnormal and unstable spindle configurations, mitotic delay at prometaphase and metaphase, and elevated aneuploidy. Conversely, loss of Hice1 had minimal effects on interphase centrosome duplication. We also found that both full-length Hice1 and Hice1-N1, which is composed of 149 amino acids of the N-terminal region, but not the mutant lacking the N-terminal region, exhibited activities of microtubule bundling and stabilization at a near-physiological concentration. Consistently, overexpression of Hice1 rendered microtubule bundles in cells resistant to nocodazole- or cold-treatment-induced depolymerization. These results demonstrate that Hice1 is a novel microtubule-associated protein important for maintaining spindle integrity and chromosomal stability, in part by virtue of its ability to bind, bundle, and stabilize microtubules.
纺锤体完整性对于高效的有丝分裂进程和准确的染色体分离至关重要。纺锤体失调常常导致结构和功能异常，最终促使分离错误和非整倍体产生，而非整倍体是大多数人类癌症的一个标志。在此，我们报告了对先前鉴定出的一种人类肉瘤抗原（基因位于19p13.11）Hice1的特性描述，Hice1是一种进化上非保守的46 kDa卷曲螺旋蛋白。Hice1表现出独特的细胞质定位，并与间期中心体和有丝分裂纺锤体相关联，优先位于纺锤体极附近。通过RNA干扰耗尽Hice1会导致纺锤体构型异常和不稳定、在前中期和中期出现有丝分裂延迟以及非整倍体增加。相反，Hice1的缺失对间期中心体复制的影响极小。我们还发现，全长Hice1和由N端区域的149个氨基酸组成的Hice1-N1，但不包括缺乏N端区域的突变体，在接近生理浓度时表现出微管成束和稳定的活性。一致地，Hice1的过表达使细胞中的微管束对诺考达唑或冷处理诱导的解聚具有抗性。这些结果表明，Hice1是一种新型的微管相关蛋白，对维持纺锤体完整性和染色体稳定性很重要，部分原因在于其结合、成束和稳定微管的能力。
