Whitaker Michael
Institute of Cell and Molecular Biosciences, Medical School, Framlington Place, Newcastle upon Tyne, UK.
Cell Calcium. 2006 Nov-Dec;40(5-6):585-92. doi: 10.1016/j.ceca.2006.08.018. Epub 2006 Oct 12.
The cell division cycle comprises successive rounds of genome replication and segregation that are never error-free. A complex signalling network chaperones cell cycle events to ensure that cell cycle progression does not occur until any errors detected are put right. The signalling network consists of cell cycle control proteins that are phosphorylated and dephosphorylated, synthesized and degraded interactively to generate a set of sensors and molecular switches that are thrown at appropriate times to permit or trigger cell cycle progression. In early embryos, discrete calcium signals have been shown to be a key component of the molecular switch mechanism. In somatic cells in contrast, the participation of calcium signals in cell cycle control is far from clear. Recent experiments in syncytial Drosophila embryos have shown that localised calcium signals in the nucleus and mitotic spindle can be detected. It appears that the nucleus comprises a calcium signalling microdomain bounded by endoplasmic reticulum that isolates the nucleus and spindle. These findings offer a possible explanation for the apparent absence of calcium signals in somatic cells during mitosis.
细胞分裂周期包括连续的基因组复制和分离轮次，而这些过程并非毫无差错。一个复杂的信号网络伴随细胞周期事件，以确保在检测到的任何错误得到纠正之前，细胞周期不会进行。该信号网络由细胞周期控制蛋白组成，这些蛋白会进行磷酸化和去磷酸化、合成和降解，相互作用以产生一组传感器和分子开关，在适当的时候启动，以允许或触发细胞周期进程。在早期胚胎中，离散的钙信号已被证明是分子开关机制的关键组成部分。相比之下，在体细胞中，钙信号在细胞周期控制中的参与情况尚不清楚。最近在合胞体果蝇胚胎中的实验表明，可以检测到细胞核和有丝分裂纺锤体中的局部钙信号。看来细胞核包含一个由内质网界定的钙信号微区，将细胞核和纺锤体隔离开来。这些发现为有丝分裂期间体细胞中明显缺乏钙信号提供了一种可能的解释。
