Twigg J, Patel R, Whitaker M
Department of Physiology, University College London, UK.
Nature. 1988 Mar 24;332(6162):366-9. doi: 10.1038/332366a0.
The cycles of DNA synthesis and chromatin condensation in dividing cells are controlled by signals from the cytoplasm. Changes in the concentration of free calcium (Cai) in the cytoplasm control a variety of cellular functions and it has thus been suggested that observed variations in Cai during the cell cycle may be the cytoplasmic signal that co-ordinates nuclear and cytoplasmic division. We show here that increases in Cai induced by the calcium-releasing second messenger inositol 1,4,5-triphosphate (Ins(1,4,5)P3), or by calcium buffers, cause premature chromatin condensation and breakdown of the nuclear envelope in sea urchin (Lytechinus pictus) early embryos. Both natural and induced chromatin condensation are prevented by calcium chelators. The nucleus becomes sensitive to the Cai signal 45 min after fertilization, but remains insensitive if protein synthesis is prevented. Our experiments demonstrate that Cai regulates the behaviour of the nucleus during the cell cycle, suggest that Ins(1,4,5)P3 is a cell cycle messenger and indicate that there is an interaction between the protein and ionic signals that control the state of chromatin during the cell cycle.
分裂细胞中DNA合成和染色质凝聚的周期受细胞质信号控制。细胞质中游离钙（Cai）浓度的变化控制着多种细胞功能，因此有人提出，在细胞周期中观察到的Cai变化可能是协调核质分裂的细胞质信号。我们在此表明，由钙释放第二信使肌醇1,4,5-三磷酸（Ins(1,4,5)P3）或钙缓冲剂诱导的Cai增加，会导致海胆（Lytechinus pictus）早期胚胎染色质过早凝聚和核膜破裂。钙螯合剂可阻止自然和诱导的染色质凝聚。受精后45分钟，细胞核对Cai信号变得敏感，但如果蛋白质合成被阻止则仍不敏感。我们的实验表明，Cai在细胞周期中调节细胞核的行为，提示Ins(1,4,5)P3是一种细胞周期信使，并表明在细胞周期中控制染色质状态的蛋白质和离子信号之间存在相互作用。
