Gonzalez-Mariscal Lorenza, Namorado Maria Del Carmen, Martin Dolores, Sierra Gerardo, Reyes Jose L
Department of Physiology, Biophysics and Neurosciences, Center for Research and Advanced Studies, Cinvestav, Ave. Instituto Politecnico Nacional 2508, Mexico, DF 07360, Mexico.
Nephrol Dial Transplant. 2006 Sep;21(9):2391-8. doi: 10.1093/ndt/gfl255. Epub 2006 Jun 9.
The tight junction (TJ) regulates the passage of ions and molecules through the paracellular pathway. In multicellular organisms, epithelial sheets function as a barrier between a variety of environments and the internal media. Therefore, TJs are required to control the passage of diverse molecules in different epithelia. The mammalian nephron constitutes a particularly relevant model of this diversity, since the paracellular transport in this organ is significantly different along the various tubular segments. Here, we have analysed the distribution of claudins-7 and -8 in Henle's loops and collecting ducts isolated from rabbit kidneys.
Renal segments were manually isolated from newborn and adult rabbit kidneys and processed for immunofluorescence. The distribution of claudins-7 and -8 was studied by confocal microscopy.
The localization of claudins-7 and -8 along Henle's loops and collecting ducts is remarkably different. While claudin-8 displays a clear cell border distribution in Henle's segment, claudin-7 shows a non-specific cytosolic staining. Moreover, in the collecting ducts, claudin-8 localizes at the TJ region, while claudin-7 shows a basolateral staining. This pattern is present from the newborn stage. The distribution of claudins along the mammalian kidney has been found to vary in different mammalian species. Accordingly, in the rabbit, we have found the expression of claudin-8 at the descending and ascending thin limbs of Henle, a distribution that differs from that found in the mouse by others.
In the rabbit Henle's loop, claudin-8 is present at the cellular borders of the descending and ascending thin limbs, while claudin-7 displays no specific labelling. Instead, at the collecting duct, both claudins are present but exhibit a different subcellular distribution.
紧密连接（TJ）调节离子和分子通过细胞旁途径的运输。在多细胞生物中，上皮层在各种环境与内部介质之间起屏障作用。因此，需要紧密连接来控制不同上皮中各种分子的运输。哺乳动物肾单位是这种多样性的一个特别相关的模型，因为该器官中的细胞旁运输在各个肾小管节段中存在显著差异。在此，我们分析了从兔肾分离的髓袢和集合管中闭合蛋白-7和-8的分布。
从新生和成年兔肾中手动分离肾节段，并进行免疫荧光处理。通过共聚焦显微镜研究闭合蛋白-7和-8的分布。
闭合蛋白-7和-8在髓袢和集合管中的定位明显不同。闭合蛋白-8在髓袢节段显示出清晰的细胞边界分布，而闭合蛋白-7显示出非特异性的胞质染色。此外，在集合管中，闭合蛋白-8定位于紧密连接区域，而闭合蛋白-7显示出基底外侧染色。这种模式从新生阶段就存在。已发现不同哺乳动物物种中闭合蛋白沿哺乳动物肾脏的分布有所不同。因此，在兔中，我们发现闭合蛋白-8在髓袢降支和升支细段表达，这种分布与其他研究在小鼠中发现的不同。
在兔髓袢中，闭合蛋白-8存在于降支和升支细段的细胞边界，而闭合蛋白-7无特异性标记。相反，在集合管中，两种闭合蛋白都存在，但表现出不同的亚细胞分布。
