Li Wing Y, Huey Catherine L, Yu Alan S L
Univ. of Southern California Keck School of Medicine, Div. of Nephrology, 2025 Zonal Ave, RMR 406, Los Angeles, CA 90033, USA.
Am J Physiol Renal Physiol. 2004 Jun;286(6):F1063-71. doi: 10.1152/ajprenal.00384.2003. Epub 2004 Jan 13.
Claudins are integral membrane proteins of the tight junction that determine the magnitude and selectivity of paracellular permeability in epithelial tissues. The mammalian renal tubule exhibits considerable heterogeneity in the permeability properties of its different segments. To determine the nephron segment localization of claudin-7 and -8, immunofluorescence staining of mouse kidney sections was performed using isoform-specific antibodies. Claudin-8 was found to be expressed primarily at the tight junction along the entire aldosterone-sensitive distal nephron and in the late segments of the thin descending limbs of long-looped nephrons. This pattern of expression is consistent with the putative role of claudin-8 as a paracellular cation barrier. By contrast, claudin-7 was found in the same nephron segments as claudin-8, but it was expressed primarily at the basolateral membrane.
紧密连接蛋白是紧密连接的整合膜蛋白，决定上皮组织中细胞旁通透性的大小和选择性。哺乳动物肾小管的不同节段在通透性特性上表现出相当大的异质性。为了确定紧密连接蛋白-7和-8在肾单位节段的定位，使用亚型特异性抗体对小鼠肾脏切片进行了免疫荧光染色。发现紧密连接蛋白-8主要沿整个醛固酮敏感的远端肾单位的紧密连接以及长袢肾单位细降支的后期节段表达。这种表达模式与紧密连接蛋白-8作为细胞旁阳离子屏障的假定作用一致。相比之下，紧密连接蛋白-7在与紧密连接蛋白-8相同的肾单位节段中被发现，但它主要在基底外侧膜表达。
