Effects of cytochalasin D on occluding junctions of intestinal absorptive cells: further evidence that the cytoskeleton may influence paracellular permeability and junctional charge selectivity.
Effects of cytochalasin D on occluding junctions of intestinal absorptive cells: further evidence that the cytoskeleton may influence paracellular permeability and junctional charge selectivity.
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DOI：
10.1083/jcb.102.6.2125
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发表时间：
1986-06
期刊：
影响因子：
--
通讯作者：
Carlson S
中科院分区：
文献类型：
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作者：
Madara JL;Barenberg D;Carlson S
肠吸收细胞可以通过细胞骨架依赖性机制调节闭塞连接的结构和功能（Madara，J.L.，1983，J.Cell Biol.，97：125-136）。为了进一步研究吸收细胞闭塞连接与细胞骨架之间的假定关系，我们使用超微结构和尤斯室技术评估了细胞松弛素 D (CD) 对豚鼠回肠闭塞连接功能和结构的影响。使用 10 微克/ml CD 可获得跨上皮电阻和连接电荷选择性的最大减量，并且这两个功能参数的剂量反应曲线高度相似。对钠和不可吸收的细胞外示踪剂甘露醇的同时通量研究的分析表明，CD 打开了跨接点分流，并且该分流可以充分解释钠渗透性的增加，从而导致阻力的降低。包括去垢剂提取的细胞骨架制剂的电子显微镜检查在内的结构研究表明，10 微克/毫升的 CD 产生了连接周围收缩环的丝状元件的凝结，并且通过扫描电子显微镜评估，这与刷状缘收缩有关。定量冷冻断裂研究揭示了吸收细胞封闭连接结构的明显畸变，包括链数量减少、链-链交联减少以及链无法阻止膜内颗粒穿过它们的运动。总的来说，这些研究表明 CD 诱导的吸收细胞骨架扰动导致跨上皮分流的产生，这可以通过跨连接途径的缺陷得到充分解释。此外，这种反应伴随着闭塞连接结构的显着结构异常。最后，闭塞连接结构和功能的异常与连接周围肌动蛋白-肌球蛋白环的结构变化和收缩相一致。这些数据表明，细胞骨架和吸收细胞的闭塞连接之间可能存在功能相关的关联。我们推测这种关联可能作为吸收细胞调节旁细胞运输的机制。
Intestinal absorptive cells may modulate both the structure and function of occluding junctions by a cytoskeleton dependent mechanism (Madara, J. L., 1983, J. Cell Biol., 97:125-136). To further examine the putative relationship between absorptive cell occluding junctions and the cytoskeleton, we assessed the effects of cytochalasin D (CD) on occluding junction function and structure in guinea pig ileum using ultrastructural and Ussing chamber techniques. Maximal decrements in transepithelial resistance and junctional charge selectivity were obtained with 10 micrograms/ml CD and the dose-response curves for these two functional parameters were highly similar. Analysis of simultaneous flux studies of sodium and the nonabsorbable extracellular tracer mannitol suggested that CD opened a transjunctional shunt and that this shunt could fully account for the increase in sodium permeability and thus the decrease in resistance. Structural studies including electron microscopy of detergent-extracted cytoskeletal preparations revealed that 10 micrograms/ml CD produced condensation of filamentous elements of the peri-junctional contractile ring and that this was associated with brush border contraction as assessed by scanning electron microscopy. Quantitative freeze-fracture studies revealed marked aberrations in absorptive cell occluding junction structure including diminished strand number, reduced strand-strand cross-linking, and failure of strands to impede the movement of intramembrane particles across them. In aggregate these studies show that CD-induced perturbation of the absorptive cell cytoskeleton results in production of a transepithelial shunt which is fully explained by a defect in the transjunctional pathway. Furthermore, substantial structural abnormalities in occluding junction structure accompany this response. Lastly, the abnormalities in occluding junction structure and function coincide with structural changes in and contraction of the peri-junctional actin-myosin ring. These data suggest that a functionally relevant association may exist between the cytoskeleton and the occluding junction of absorptive cells. We speculate that such an association may serve as a mechanism by which absorptive cells regulate paracellular transport.