Molecular Radiation Oncology, Center for Cancer Research, NIH, Bethesda, Maryland, USA.
Anat Rec (Hoboken). 2010 Jul;293(7):1175-83. doi: 10.1002/ar.21163.
Proteins in the claudin family are a main component of tight junctions and form a seal that modulates paracellular transport in intestinal epithelium. This research tests the hypothesis that claudins 3, 5, and 16 will appear in the epithelium of embryonic intestine during functional differentiation. Immunohistochemistry is utilized to explore the developmental patterns of claudin-3, -5, and -16 proteins in the epithelium of embryonic chick intestine from 9 days prior to hatching through the early post-hatch period. These claudin proteins either changed their cellular localization or first appeared around the time of hatching. After hatching, claudin-3 expression was prominent in basal-lateral regions of the epithelium along the entire villus, but was absent from crypts. Claudin-5 was expressed most strongly in the crypt and lower villus epithelium within junctional complexes, whereas immunostaining of claudin-16 was localized within goblet cells of the upper villus region. The relative mRNA levels of claudin-3, -5, and -16 showed similar patterns; transcript levels rose between 18 and 20 days of development, then dropped by 2 days post-hatch. Results of this work indicate that the claudin proteins assume their final locations within the epithelium around the time of hatching, suggesting that in addition to their known barrier and fence functions within tight junctions, these claudins may have additional roles in the differentiation and/or physiological function of chick intestine. The localization of claudin-16 to goblet cells and its distribution in the more mature cells of the upper villus region suggest an unexpected role in goblet cell maturation and mucus secretion.
紧密连接中的 claudin 家族蛋白是其主要组成部分，形成的密封结构可调节肠道上皮细胞的旁细胞转运。本研究检验了这样一个假设，即在胚胎肠道的功能分化过程中，claudin-3、claudin-5 和 claudin-16 会出现在肠道上皮细胞中。免疫组织化学技术被用于研究鸡胚肠上皮细胞中 claudin-3、claudin-5 和 claudin-16 蛋白在孵化前 9 天到孵化后早期的发育模式。这些 claudin 蛋白或改变其细胞定位，或在孵化时首次出现。孵化后，claudin-3 在整个绒毛的上皮细胞基底层表达，但在隐窝中不存在。claudin-5 在隐窝和下部绒毛上皮细胞的连接复合物中表达最强，而 claudin-16 的免疫染色则定位于绒毛上部区域的杯状细胞中。claudin-3、claudin-5 和 claudin-16 的相对 mRNA 水平显示出相似的模式；转录水平在发育的 18 到 20 天之间上升，然后在孵化后 2 天下降。这项工作的结果表明，claudin 蛋白在孵化时在肠道上皮细胞中占据其最终位置，这表明除了在紧密连接中具有已知的屏障和围栏功能外，这些 claudin 可能在小鸡肠道的分化和/或生理功能中具有额外的作用。claudin-16 定位于杯状细胞，并且在绒毛上部区域更成熟的细胞中分布，这表明其在杯状细胞成熟和粘液分泌中具有意想不到的作用。
