Department of Biological Sciences, University of Toledo, Toledo, OH 43606.
Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606.
Mol Biol Cell. 2021 Jan 1;32(1):15-27. doi: 10.1091/mbc.E20-09-0609. Epub 2020 Nov 11.
The role of calcium signaling in cytokinesis has long remained ambiguous. Past studies of embryonic cell division discovered that calcium concentration increases transiently at the division plane just before cleavage furrow ingression, suggesting that these calcium transients could trigger contractile ring constriction. However, such calcium transients have only been found in animal embryos and their function remains controversial. We explored cytokinetic calcium transients in the fission yeast by adopting GCaMP, a genetically encoded calcium indicator, to determine the intracellular calcium level of this model organism. We validated GCaMP as a highly sensitive calcium reporter in fission yeast, allowing us to capture calcium transients triggered by osmotic shocks. We identified a correlation between the intracellular calcium level and cell division, consistent with the existence of calcium transients during cytokinesis. Using time-lapse microscopy and quantitative image analysis, we discovered calcium spikes both at the start of cleavage furrow ingression and the end of cell separation. Inhibition of these calcium spikes slowed the furrow ingression and led to frequent lysis of daughter cells. We conclude that like the larger animal embryos, fission yeast triggers calcium transients that may play an important role in cytokinesis (197).
钙信号在胞质分裂中的作用一直存在争议。过去对胚胎细胞分裂的研究发现，在分裂平面处的卵裂沟内陷之前，钙离子浓度会短暂增加，这表明这些钙瞬变可能触发收缩环的收缩。然而，这种钙瞬变仅在动物胚胎中被发现，其功能仍存在争议。我们通过采用 GCaMP（一种遗传编码的钙指示剂）来探索裂殖酵母中的胞质分裂钙瞬变，以确定这种模式生物的细胞内钙水平。我们验证了 GCaMP 在裂殖酵母中是一种高度敏感的钙报告基因，允许我们捕捉到由渗透压冲击引发的钙瞬变。我们发现细胞内钙水平与细胞分裂之间存在相关性，这与胞质分裂过程中存在钙瞬变一致。通过延时显微镜和定量图像分析，我们在卵裂沟内陷开始和细胞分离结束时都发现了钙峰。抑制这些钙峰会减缓卵裂沟的内陷，并导致子细胞频繁裂解。我们得出结论，与较大的动物胚胎一样，裂殖酵母触发钙瞬变，这可能在胞质分裂中发挥重要作用(197)。
