Tournier J F, Lopez A, Gas N, Tocanne J F
Centre de Recherches de Biochimie et de Génétiques Cellulaire du CNRS, Toulouse, France.
Exp Cell Res. 1989 Apr;181(2):375-84. doi: 10.1016/0014-4827(89)90095-5.
As with other epithelia, the question arises of whether the endothelial cell junctions participate in cell polarization, restrict the localization of lipid molecules, and lead to differences in their lateral motion between the apical and basolateral plasma membranes. We found that in bovine aortic endothelium in culture, the localization of the lipophilic probe 5N-(hexadecanoyl)-aminofluorescein (HEDAF) was markedly affected by the presence of cell junctions. At confluence, the probe was observed to be restricted to the exoplasmic leaflet of the apical plasmalemma. It was detected in the basal membrane only after disruption of the cell junctions, whereas the cells remained firmly bound to the underlying extracellular matrix. Fluorescence recovery after photobleaching (FRAP) experiments indicated that the endothelial confluent cell monolayer forms a mosaic of closed diffusion areas in which the probe molecules are free to diffuse. For the first time, and using a new mathematical approach, it was possible to estimate the diameter of these diffusion areas. Values in the range 14-33 microns were found which correlate well with the actual measured diameters of 14 to 26 microns for the apical pole of individual cells. Moreover, cell junctions were found to affect the dynamics of the probe. When the cell junctions were disrupted, the lateral diffusion coefficient D of HEDAF was found to be the same in both apical and basal membranes. It regained its initial higher value in the apical poles when cell contacts were restored. This strongly suggests that in vascular endothelium, cell junctions affect overall plasma membrane organization in a reversible manner.
与其他上皮细胞一样，内皮细胞连接是否参与细胞极化、限制脂质分子的定位以及导致其在顶端和基底外侧质膜之间横向运动的差异，这些问题随之而来。我们发现，在培养的牛主动脉内皮细胞中，亲脂性探针5N-（十六烷酰基）-氨基荧光素（HEDAF）的定位受到细胞连接存在的显著影响。汇合时，观察到该探针仅限于顶端质膜的外质小叶。只有在细胞连接被破坏后，才在基底膜中检测到它，而细胞仍牢固地附着在下面的细胞外基质上。光漂白后荧光恢复（FRAP）实验表明，内皮汇合细胞单层形成了封闭扩散区域的镶嵌结构，其中探针分子可以自由扩散。首次使用一种新的数学方法，可以估计这些扩散区域的直径。发现其值在14 - 33微米范围内，这与单个细胞顶端极实际测量的14至26微米直径密切相关。此外，发现细胞连接会影响探针的动力学。当细胞连接被破坏时，发现HEDAF在顶端和基底膜中的横向扩散系数D是相同的。当细胞接触恢复时，它在顶端极恢复到其初始较高值。这强烈表明，在血管内皮中，细胞连接以可逆方式影响整体质膜组织。
