Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, Bath, UK.
Biochem J. 2010 Sep 1;430(2):207-13. doi: 10.1042/BJ20100883.
RASSF7, a member of the N-terminal Ras association domain family, has increased expression in various cancers and, on the basis of our previous work in Xenopus embryos, may be a regulator of mitosis. In the present study, we address, for the first time, the role of human RASSF7 in mitosis. We demonstrate that RASSF7 is expressed in a broad range of different cell types and that this expression could be enhanced following exposure to hypoxia. Knocking down RASSF7 in human cell lines inhibited cell growth and induced defects in mitosis, including aberrant spindle formation and a failure in chromosomal congression. In order to understand the molecular basis of the defects in more detail, we analysed the activity of mitotic signalling proteins and found that activation of Aurora B did not occur in cells in which RASSF7 was knocked down. We also show that endogenous RASSF7 protein localizes to the centrosome and demonstrate using microtubule-regrowth assays that RASSF7 is an important regulator of microtubule dynamics. On the basis of these observations, we propose that, owing to its key role in regulating the microtubule cytoskeleton, RASSF7 is required for mitosis in human cells.
RASSF7 是 N 端 Ras 相关结构域家族的成员，在各种癌症中表达增加，基于我们之前在非洲爪蟾胚胎中的工作，它可能是有丝分裂的调节剂。在本研究中，我们首次研究了人 RASSF7 在有丝分裂中的作用。我们证明 RASSF7 在广泛的不同细胞类型中表达，并且这种表达可以在暴露于缺氧后增强。在人细胞系中敲低 RASSF7 会抑制细胞生长并诱导有丝分裂缺陷，包括纺锤体异常形成和染色体聚集中的失败。为了更详细地了解缺陷的分子基础，我们分析了有丝分裂信号蛋白的活性，发现 RASSF7 敲低的细胞中不会发生 Aurora B 的激活。我们还表明，内源性 RASSF7 蛋白定位于中心体，并通过微管再生实验证明 RASSF7 是微管动力学的重要调节剂。基于这些观察结果，我们提出由于其在调节微管细胞骨架中的关键作用，RASSF7 是人细胞有丝分裂所必需的。
