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Regulatory role of calcium mobilization in retinal neurogenesis

钙动员在视网膜神经发生中的调节作用

基本信息

批准号：
13671850
负责人：
YAMASHITA Masayuki
金额：
$ 1.92万
依托单位：
Nara Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13671850/
关键词：
calcium ion retina neuroepithelium nuclear envelope cell cycle confocal microscope calcium mobilization capacitative calcium entry 小胞体

项目摘要

Intracellular calcium is a regulatory signal for cell proliferation. To reveal calcium signal dynamics during cell cycle, we applied calcium fluorescence imaging to the retinal neuroepithelium of chick embryo (embryonic day 3, E3, and E6), where the soma changes its position during the cell cycle. Purinoceptors were stimulated by the application of adenosine triphosphate (ATP) to cause calcium release from calcium stores, since the purinoceptor activation promotes DNA synthesis. The ATP-induced calcium rises occurred in the nucleoplasm of cells at around S phase as revealed by confocal fluorescence microscopy in the E3 retina. The calcium rise declined in M-phase cells and postmitotic cells (retinal ganglion cells). These results were confirmed in the vertical slice preparation of the E6 retina. The soma of S-phase cell is located in the inner layer of the retinal neuroepithelium and issues an outer process, which extends to the ventricular surface. Fluorescent probes for endoplasmic reticulum (ER) showed that the ERs in the outer process and the nuclear envelope or peri-nuclear ER formed the calcium store. Depletion of the calcium store induced capacitative calcium entry, which caused calcium rises in the terminal of outer process and soma. These results suggest that the calcium signaling to nucleus via the store-operated system including the ERs in the outer process is crucial for the cell cycle progression in the retinal neuroepithelium. Spontaneous calcium oscillation was also observed in the nucleoplasm of S-phase cells. The mechanism of calcium oscillation and the functional significance of the polarized structure of retinal neuroepithelium for calcium signaling will be studied.

细胞内钙是细胞增殖的调节信号。为了揭示细胞周期中钙信号的动态变化，我们对鸡胚胎(胚胎3天、E3天和E6天)的视网膜神经上皮进行了钙荧光成像，胞体在细胞周期中改变了位置。由于嘌呤受体的激活促进了DNA的合成，因此应用三磷酸腺苷(ATP)可以刺激嘌呤受体，使钙从钙库中释放出来。E3视网膜共聚焦荧光显微镜显示，三磷酸腺苷诱导的钙升高发生在细胞的核浆中，约在S时相。M期细胞和有丝分裂后细胞(视网膜神经节细胞)钙升高下降。这些结果在E6视网膜的垂直切片制备中得到了证实。S期细胞胞体位于视网膜神经上皮细胞的内层，向外发出突起，延伸至脑室表面。内质网(ER)荧光探针显示，外突内的内质网和核膜或核周内质网形成钙库。外突末端和胞体的钙离子浓度升高，导致钙库耗竭，引起容量性钙离子内流。这些结果表明，钙信号通过包括外突起的内质网在内的存储操作系统到达细胞核，对视网膜神经上皮细胞的细胞周期进程至关重要。在S期细胞的核浆中也观察到自发的钙振荡。将研究钙振荡的机制和视网膜神经上皮细胞极化结构对钙信号的功能意义。