Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan.
Biochem Biophys Res Commun. 2010 Mar 12;393(3):390-6. doi: 10.1016/j.bbrc.2010.02.002. Epub 2010 Feb 6.
In multicellular organisms, epithelia separate and divide the internal environment maintaining appropriate conditions in each compartment. To maintain homeostasis in these compartments, claudins, major cell adhesion molecules in tight junctions (TJs), regulate movements of several substances through the paracellular pathway (barrier function). In this study, we investigated effects of the flux of several substances between apical and basolateral side on paracellular transport and TJ protein localization. NaCl flux from apical to basolateral side increased paracellular conductance (Gp) and recruited claudin-1 from lateral cell membrane to the apical end with the colocalization with occludin, one of the TJ proteins concentrated at TJ strands. Oppositely-directed flux of sucrose against NaCl flux inhibited these reactions and same directional flux of sucrose with NaCl enhanced the increase of Gp, whereas 10-kDa dextran inhibited these reactions regardless of the side of administration. Our present findings indicated that TJ protein localization and barrier function are regulated depending on the environmental differences between apical and basolateral side.
在多细胞生物中，上皮组织将内部环境分隔开来，并维持每个隔室的适当条件。为了在这些隔室中维持体内平衡，紧密连接（TJ）中的主要细胞粘附分子 Claudin 调节通过细胞旁途径（屏障功能）的几种物质的运动。在这项研究中，我们研究了几种物质从顶端到基底外侧侧的通量对细胞旁转运和 TJ 蛋白定位的影响。从顶端到基底外侧的 NaCl 通量增加了细胞旁电导率（Gp），并将 Claudin-1 从侧细胞膜募集到 TJ 链集中的 Occludin 之一的顶端末端。与 NaCl 通量相反方向的蔗糖通量抑制了这些反应，而具有 NaCl 的相同方向的蔗糖通量增强了 Gp 的增加，而 10-kDa 葡聚糖则抑制了这些反应，而与给药侧无关。我们目前的发现表明，TJ 蛋白定位和屏障功能取决于顶端和基底外侧侧之间的环境差异而受到调节。
