CHANGES IN INTRACELLULAR CALCIUM DURING THE DEVELOPMENT OF EPITHELIAL POLARITY AND JUNCTIONS
CHANGES IN INTRACELLULAR CALCIUM DURING THE DEVELOPMENT OF EPITHELIAL POLARITY AND JUNCTIONS
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DOI：
10.1073/pnas.89.13.6162
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发表时间：
1992-07-01
影响因子：
11.1
通讯作者：
SILVER, RB
中科院分区：
文献类型：
--
作者：
NIGAM, SK;RODRIGUEZBOULAN, E;SILVER, RB
用培养的Madin-Darby犬肾(MDCK)细胞建立的“钙开关”模型可用于研究上皮极性和连接形成的生物发生，并为极化上皮组织形态发生的早期步骤提供洞察力。当细胞外钙离子从细胞外钙离子的10倍变化到细胞外钙离子浓度的10倍时，细胞外钙离子的变化呈现出一种增减稳的复杂模式。相反，细胞内pH[用2‘，7’-双(2-羧乙基)-5(和6)-羧基荧光素(BCECF)监测]在研究期间没有变化。当比较几个细胞的细胞内钙曲线时，细胞内钙水平的上升速度和峰值水平明显不均匀，这可能反映了细胞之间在建立连接和极性方面的异质性。细胞内钙离子的数字成像证实了这一过程的异质性，甚至在MDCK细胞的“克隆”系中也存在这种异质性，表明这种异质性是该过程固有的，而不仅仅是MDCK细胞群体中轻微遗传变异的函数。在刚刚建立细胞间联系的细胞对中，通常一个细胞表现出比另一个细胞更大的细胞内钙离子增加。在细胞-细胞接触部位，细胞内钙离子经常出现明显的局部性变化(高于基础水平)，有时似乎延伸到细胞-细胞接触点之外。由于细胞-细胞接触区域也是在极性发育过程中形成连接和含有顶膜的囊泡融合的地方，我们推测细胞内钙离子的整体和局部变化在这些事件中起到了作用。
The "Ca2+ switch" model with cultured Madin-Darby canine kidney (MDCK) cells is useful in studying the biogenesis of epithelial polarity and junction formation and provides insight into early steps in the morphogenesis of polarized epithelial tissues. When extracellular Ca2+ in the medium is changed from 10-fold during the switch and gave a complex pattern of increase, decrease, and stabilization. In contrast, intracellular pH [monitored with 2',7'-bis(2-carboxyethyl)-5(and 6)-carboxyfluorescein (BCECF)] did not change during the period studied. When intracellular Ca2+ curves in several cells were compared, considerable heterogeneity in the rate of increase of intracellular Ca2+ levels and in peak levels was evident, perhaps reflecting the heterogeneity among cells in establishing junctions and polarity. The heterogeneity of the process was confirmed by digital imaging of intracellular Ca2+ and was present even in a "clonal" line of MDCK cells, indicating the heterogeneity was intrinsic to the process and not simply a function of slight genetic variation within the population of MDCK cells. In pairs of cells that had barely established cell-cell contact, often one cell exhibited a much greater increase in intracellular Ca2+ than the other cell in the pair. At the site of cell-cell contact, an apparent localized change (an increase over the basal level) in intracellular Ca2+ was frequently present and occasionally appeared to extend beyond the point of cell-cell contact. Since the region of cell-cell contact is also the site where junctions form and where vesicles containing apical membranes fuse during the development of polarity, we postulate a role for global and local changes in intracellular Ca2+ in these events.