Fukagawa T, Pendon C, Morris J, Brown W
Biochemistry Department, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
EMBO J. 1999 Aug 2;18(15):4196-209. doi: 10.1093/emboj/18.15.4196.
CENP-C is an evolutionarily conserved centromeric protein. We have used the chicken DT40 cell line to test the idea that CENP-C is sufficient as well as necessary for the formation of a functional centromere. We have compared the effects of disrupting the localization of CENP-C with those of inducibly overexpressing the protein. Removing CENP-C from the centromere causes disassembly of the centromere protein complex and blocks cells at the metaphase-anaphase junction. Overexpressed CENP-C is associated with an increase in errors of chromosome segregation and inhibits the completion of mitosis. However, the excess CENP-C does not disrupt the native centromeres detectably and does not associate with another conserved centromere protein, ZW10. The distribution of the excess CENP-C changes during the cell cycle. In metaphase, the excess CENP-C coats the chromosome arms. At the metaphase-anaphase transition, the excess CENP-C clusters, and during interphase it is present in large bodies which form around pre-existing centromeres which are also clustered. These results indicate that CENP-C is necessary but not sufficient for the formation of a functional centromere and suggest that the structure of CENP-C may be regulated during the cell cycle.
着丝粒蛋白C（CENP-C）是一种进化上保守的着丝粒蛋白。我们利用鸡DT40细胞系来验证CENP-C对于功能性着丝粒的形成不仅是必要的而且是充分的这一观点。我们比较了破坏CENP-C定位的影响与诱导性过表达该蛋白的影响。从着丝粒中去除CENP-C会导致着丝粒蛋白复合体解体，并使细胞停滞在中期-后期交界处。过表达的CENP-C与染色体分离错误的增加相关，并抑制有丝分裂的完成。然而，过量的CENP-C并未可检测地破坏天然着丝粒，也未与另一种保守的着丝粒蛋白ZW10结合。过量CENP-C的分布在细胞周期中会发生变化。在中期，过量的CENP-C覆盖染色体臂。在中期-后期转换时，过量的CENP-C聚集，而在间期它存在于围绕预先存在的着丝粒形成的大的聚集体中，这些着丝粒也是聚集的。这些结果表明，CENP-C对于功能性着丝粒的形成是必要的但不是充分的，并提示CENP-C的结构可能在细胞周期中受到调控。
