Claudin-3 acts as a sealing component of the tight junction for ions of either charge and uncharged solutes
Claudin-3 acts as a sealing component of the tight junction for ions of either charge and uncharged solutes
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DOI：
10.1016/j.bbamem.2010.07.014
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发表时间：
2010-11-01
影响因子：
3.4
通讯作者：
Fromm, Michael
中科院分区：
文献类型：
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作者：
Milatz, Susanne;Krug, Susanne M.;Fromm, Michael
上皮和内皮的细胞旁屏障是由包括claudin-3在内的几种紧密连接蛋白建立的。虽然claudin-3存在于包括皮肤、肺、肾、肠和内皮在内的许多上皮细胞中，但其功能尚未明确。因此，我们通过用人claudin-3 cDNA稳定转染MDCK II肾小管细胞来鉴定claudin-3。分析了两个克隆系统，分别表现出高或低的claudin-2表达。其他基因的表达没有变化。在超微结构上，紧密连接的链转变为不间断的圆形网状环。在功能上，与载体对照相比，转染claudin-3的单层膜的细胞旁抗性强烈升高，导致经上皮抗性增加。对一价、二价阳离子和阴离子的渗透性降低。在高claudin-2体系中，claudin-3降低了claudin-2诱导的阳离子选择性，而在低claudin-2体系中没有观察到电荷偏好，后者反映了claudin-3的“内在”作用。此外，细胞旁示踪剂荧光素（332 Da）和FD-4 （4 kDa）的通过量减少，而对水的渗透性不受影响。我们证明了claudin-3改变了紧密的连接网络，并封闭了细胞旁通路，阻止带电和不带电溶质的小离子通过。因此，在肾模型上皮中，claudin-3作为一般的屏障形成蛋白。(C) 2010 Elsevier B.V.版权所有
The paracellular barrier of epithelia and endothelia is established by several tight junction proteins including claudin-3. Although claudin-3 is present in many epithelia including skin, lung, kidney, and intestine and in endothelia, its function is unresolved as yet. We therefore characterized claudin-3 by stable transfection of MDCK II kidney tubule cells with human claudin-3 cDNA. Two clone systems were analyzed, exhibiting high or low claudin-2 expression, respectively. Expression of other claudins was unchanged. Ultrastructurally, tight junction strands were changed toward uninterrupted and rounded meshwork loops. Functionally, the paracellular resistance of claudin-3-transfected monolayers was strongly elevated, causing an increase in transepithelial resistance compared to vector controls. Permeabilities for mono- and divalent cations and for anions were decreased. In the high-claudin-2 system, claudin-3 reduced claudin-2-induced cation selectivity, while in the low-claudin-2 system no charge preference was observed, the latter thus reflecting the "intrinsic" action of claudin-3. Furthermore, the passage of the paracellular tracers fluorescein (332 Da) and FD-4 (4 kDa) was decreased, whereas the permeability to water was not affected. We demonstrate that claudin-3 alters the tight junction meshwork and seals the paracellular pathway against the passage of small ions of either charge and uncharged solutes. Thus, in a kidney model epithelium, claudin-3 acts as a general barrier-forming protein. (C) 2010 Elsevier B.V. All rights reserved.