Structure and function of tight junctions involved in slit diaphragms

紧密连接是肾病条件下肾小球足细胞的主要细胞间连接。它们的必要组成部分，claudins，仍然有待鉴定。利用离体大鼠肾小球cDNA进行的绝对定量实时PCR显示，claudin-5是肾小球中表达最丰富的claudin。原位杂交和免疫定位研究表明，claudin-5主要定位于足细胞。Claudin-5蛋白分布于足细胞的整个表面，包括裂孔隔膜，并倾向于集中在嘌呤霉素氨基糖苷肾病的紧密连接。免疫沉淀研究，使用抗claudin-5和肾小球裂解物揭示了协会的claudin-5和nephrin。它的结论是，claudin-5是一个主要的claudin足细胞中表达，并在肾病的紧密连接的形成可能是由于局部招聘的claudin-5，而不是由于总的上调的claudin蛋白水平。

Tight junctions are the main intercellular junctions of podocytes of the renal glomerulus under nephrotic conditions. Their requisite components, claudins, still remain to be identified. Absolute quantitative real-time PCR using cDNA of isolated rat glomeruli showed that claudin-5 was the most abundantl claudin expressed in glomeruli. In situ hybridization and immunolocalization studies revealed that claudin-5 was localized mainly in podocytes. Claudin-5 protein was observed on the entire surface of podocytes including slit diaphragms, and was inclined to be concentrated on tight junctions in puromycin aminonucleoside nephrosis. Immunoprecipitation studies using anti-claudin-5 and glomerular lysates revealed the association of claudin-5 and nephrin. It is concluded that claudin-5 is a main claudin expressed in podocytes and that the formation of tight junctions in the nephrosis may be due to local recruitment of claudin-5 rather than due to total upregulation of the claudin protein levels.