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首页> 外文期刊>American Journal of Physiology >Claudins create charge-selective channels in the paracellular pathway between epithelial cells.
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Claudins create charge-selective channels in the paracellular pathway between epithelial cells.

机译：claudins在上皮细胞之间的旁细胞途径中创建电荷选择通道。

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摘要

Epithelia separate tissue spaces by regulating the passage of ions, solutes, and water through both the transcellular and paracellular pathways. Paracellular permeability is defined by intercellular tight junctions, which vary widely among tissues with respect to solute flux, electrical resistance, and ionic charge selectivity. To test the hypothesis that members of the claudin family of tight junction proteins create charge selectivity, we assessed the effect of reversing the charge of selected extracellular amino acids in two claudins using site-directed mutagenesis. Claudins were expressed in cultured Madin-Darby canine kidney cell monolayers under an inducible promoter, and clones were compared with and without induction for transmonolayer electrical resistance and dilution potentials. Expression and localization of claudins were determined by immunoblotting, immunofluorescence microscopy, and freeze-fracture electron microscopy. We observed that substituting a negative for a positive charge at position 65 in the first extracellular domain of claudin-4 increased paracellular Na+ permeability. Conversely, substituting positive for negative charges at three positions in the first extracellular domain of claudin-15, singly and in combination, reversed paracellular charge selectivity from a preference for Na+ to Cl-. These results support a model where claudins create charge-selective channels in the paracellular space.
机译：上皮细胞通过调节离子，溶质和水通过跨细胞和旁细胞途径的通道来分隔组织空间。细胞旁通透性由细胞间紧密连接定义，在溶质通量，电阻和离子电荷选择性方面，组织间紧密连接变化很大。为了测试关于紧密连接蛋白claudin家族成员产生电荷选择性的假设，我们使用定点诱变评估了逆转两个claudin中所选细胞外氨基酸电荷的效果。 claudins在诱导型启动子下在培养的Madin-Darby犬肾细胞单层中表达，并比较了有无诱导的克隆对单层电阻和稀释电位的影响。通过免疫印迹，免疫荧光显微镜和冷冻断裂电子显微镜确定claudin的表达和定位。我们观察到，在claudin-4的第一个胞外域中，位置65处的负电荷取代了正电荷，增加了细胞旁Na +的通透性。相反，在claudin-15的第一个胞外域的三个位置上用正电荷代替负电荷，单独地和组合地将副细胞电荷选择性从对Na +的偏好转向为Cl-。这些结果支持了一种模型，其中claudins在副细胞空间中创建了电荷选择通道。

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