Claudin‐7 Expressed on Lateral Membrane of Rat Epididymal Epithelium does not Form Aberrant Tight Junction Strands
Claudin‐7 Expressed on Lateral Membrane of Rat Epididymal Epithelium does not Form Aberrant Tight Junction Strands
复制标题
DOI：
10.1002/ar.20597
复制
发表时间：
2007-11
期刊：
影响因子：
--
通讯作者：
T. Inai;Akihito Sengoku;E. Hirose;H. Iida;Y. Shibata
中科院分区：
文献类型：
--
作者：
T. Inai;Akihito Sengoku;E. Hirose;H. Iida;Y. Shibata
紧密连接蛋白是紧密连接（TJ）处的完整膜蛋白，并形成TJ链。在本研究中，我们发现claudin-7定位于沿着附睾上皮的整个侧膜，包括整个附睾的顶端连接区，但claudin-8仅限于顶端连接区。这一发现提出了可能性，异常TJ链可能形成的侧膜。因此，我们集中研究TJ链是否存在于附睾上皮的侧膜上。冷冻断裂电子显微镜检查显示，除起始段外，在附睾所有节段中仅在少数主细胞中观察到异常TJ链，表明异常TJ链的发生非常罕见。异常TJ链是光滑的，在原生质面没有细分成单个颗粒，在细胞外面的互补沟几乎没有颗粒。附睾远端头和体中的异常TJ股伴有许多囊泡样结构，但附睾近端头和尾中的异常TJ股不伴有囊泡样结构。这些结果表明，侧膜中的大部分claudin-7可能以非聚合形式存在，并且可能发挥除形成TJ链之外的一些不同作用，例如，在形成claudin蛋白库或加强细胞粘附中。Anat Rec，1431 - 1438，2007年。© 2007 Wiley利斯公司
Claudins are integral membrane proteins at tight junctions (TJs) and form TJ strands. In the present study, we found that claudin‐7 was localized along the entire lateral membranes of epididymal epithelium, including the apical junctional region throughout the epididymis, but claudin‐8 was restricted to the apical junctional region. This finding raises the possibility that aberrant TJ strands may be formed on lateral membranes. Thus, we focused on examining whether TJ strands exist on lateral membranes of epididymal epithelium. Freeze‐fracture electron microscopy showed that aberrant TJ strands were observed in only a few principal cells in all segments of the epididymis except for the initial segment, indicating that the occurrence of aberrant strands is very rare. Aberrant TJ strands were smooth and not subdivided into individual particles in the protoplasmic face, and complementary grooves in the extracellular face were almost free of particles. Aberrant TJ strands in the distal caput and corpus epididymis were accompanied by many vesicle‐like structures but those in the proximal caput and cauda epididymis were not. These results suggest that most of claudin‐7 in lateral membranes may exist in a nonpolymerized form and may play some different roles other than the formation of TJ strands, for example, in the formation of a pool of claudin proteins or in the reinforcement of cell adhesion. Anat Rec, 1431‐1438, 2007. © 2007 Wiley‐Liss, Inc.