scholarly journals Biology of claudins

2008 ◽  
Vol 295 (4) ◽  
pp. F867-F876 ◽  
Author(s):  
Susanne Angelow ◽  
Robert Ahlstrom ◽  
Alan S. L. Yu

Claudins are a family of tight junction membrane proteins that regulate paracellular permeability of epithelia, likely by forming the lining of the paracellular pore. Claudins are expressed throughout the renal tubule, and mutations in two claudin genes are now known to cause familial hypercalciuric hypomagnesemia with nephrocalcinosis. In this review, we discuss recent advances in our understanding of the physiological role of various claudins in normal kidney function, and in understanding the fundamental biology of claudins, including the molecular basis for selectivity of permeation, claudin interactions in tight junction formation, and regulation of claudins by protein kinases and other intracellular signals.

2017 ◽  
Vol 137 (4) ◽  
pp. 884-893 ◽  
Author(s):  
Elena Rahn ◽  
Katharina Thier ◽  
Philipp Petermann ◽  
Matthias Rübsam ◽  
Peter Staeheli ◽  
...  

2004 ◽  
Vol 286 (6) ◽  
pp. F1063-F1071 ◽  
Author(s):  
Wing Y. Li ◽  
Catherine L. Huey ◽  
Alan S. L. Yu

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.


2007 ◽  
Vol 293 (1) ◽  
pp. F166-F177 ◽  
Author(s):  
Susanne Angelow ◽  
Randa El-Husseini ◽  
Sanae A. Kanzawa ◽  
Alan S. L. Yu

Claudins form a family of transmembrane tight junction proteins that play a key role in control and selectivity of paracellular transport. Mutations in claudin-19, which is expressed in kidney, retina, and myelinated peripheral neurons, were identified in familial hypomagnesemia with hypercalciuria and nephrocalcinosis, a hereditary disease causing renal Mg2+ and Ca2+ wasting. Here, we studied the distribution and possible functional role of claudin-19 in the renal tubule. By immunofluorescence staining of mouse kidney, claudin-19 was found to be expressed at the tight junction of the thick ascending limb of Henle, the major site of paracellular Mg2+ reabsorption, where it colocalized with claudin-16, as well as in the thin ascending limb. The role of claudin-19 in paracellular transport was tested by stable transfection into Madin Darby canine kidney II TetOff cells to generate inducible cell lines. Claudin-19 increased the transepithelial electrical resistance and decreased permeability to monovalent and divalent cations, while anion and urea permeability were not affected. Our data suggest that claudin-19 acts as a selective cation barrier at the tight junction. This would be consistent with its physiological role to electrically seal myelinated peripheral neurons. The normal role of claudin-19 in renal tubule function remains to be determined.


1983 ◽  
Vol 96 (3) ◽  
pp. 693-702 ◽  
Author(s):  
EB Griepp ◽  
WJ Dolan ◽  
ES Robbins ◽  
DD Sabatini

Measurements of the transepithelial electrical resistance correlated with freeze-fracture observations have been used to study the process of tight junction formation under various experimental conditions in monolayers of the canine kidney epithelial cell line MDCK. Cells derived from previously confluent cultures and plated immediately after trypsin- EDTA dissociation develop a resistance that reaches its maximum value of several hundred ohms-cm(2) after approximately 24 h and falls to a steady-state value of 80-150 ohms- cm(2) by 48 h. The rise in resistance and the development of tight junctions can be completely and reversibly prevented by the addition of 10 μg/ml cycloheximide at the time of plating, but not when this inhibitor is added more than 10 h after planting. Thus tight junction formation consists of separable synthetic and assembly phases. These two phases can also be dissociated and the requirement for protein synthesis after plating eliminated if, following trypsinization, the cells are maintained in spinner culture for 24 h before plating. The requirement for protein synthesis is restored, however, if cells maintained in spinner culture are treated with trypsin before plating. Actinomycin D prevents development of resistance only in monolayers formed from cells derived from sparse rather than confluent cultures, but new mRNA synthesis is not required if cells obtained from sparse cultures are maintained for 24 h in spinner culture before plating. Once a steady-state resistance has been reached, its maintenance does not require either mRNA or protein synthesis; in fact, inhibition of protein synthesis causes a rise in the resistance over a 30-h period. Following treatments that disrupt the junctions in steady- state monolayers recovery of resistance also does not require protein synthesis. These observations suggest that proteins are involved in tight junction formation. Such proteins, which do not turn over rapidly under steady-state conditions, are destroyed by trypsinization and can be resynthesized in the absence of stable cell-cell or cell-substratum contact. Messenger RNA coding for proteins involved in tight junction formation is stable except when cells are sparsely plated, and can also be synthesized without intercellular contacts or cell-substratum attachment.


Development ◽  
1993 ◽  
Vol 117 (3) ◽  
pp. 1145-1151 ◽  
Author(s):  
Q. Javed ◽  
T.P. Fleming ◽  
M. Hay ◽  
S. Citi

The expression of the tight junction peripheral membrane protein, cingulin (140 × 10(3) M(r), was investigated in mouse eggs and staged preimplantation embryos by immunoblotting and immunoprecipitation. Polyclonal antibody to chicken brush cingulin detected a single 140 × 10(3) M(r) protein in immunoblots of unfertilised eggs and all preimplantation stages. Relative protein levels were high in eggs and early cleavage stages, declined during later cleavage and increased again in expanding blastocysts. Quantitative immunoprecipitation of metabolically labelled eggs and staged embryos also revealed a biphasic pattern for cingulin synthesis with relative net levels being high in unfertilised eggs, minimal during early cleavage, rising 2.3-fold specifically at the onset of compaction (8-cell stage, when tight junction formation begins), and increasing further at a linear rate during morula and blastocyst stages. Cingulin synthesis in eggs is not influenced by fertilisation (or aging, if unfertilised), but this level declines sharply after first cleavage. These results indicate that cingulin is expressed by both maternal and embryonic genomes. The turnover of maternal cingulin (unfertilised eggs) and embryonic cingulin at a stage before tight junction formation begins (4-cell stage) is higher (t1/2 approximately 4 hours) than cingulin synthesised after tight junction formation (blastocysts; t1/2 approximately 10 hours). This increase in cingulin stability is reversed in the absence of extracellular calcium. Cingulin synthesis is also tissue-specific in blastocysts, being up-regulated in trophectoderm and down-regulated in the inner cell mass. Taken together, the results suggest that (i) cingulin may have a role during oogenesis and (ii) cell-cell contact patterns regulate cingulin biosynthesis during early morphogenesis, contributing to lineage-specific epithelial maturation.


Circulation ◽  
2020 ◽  
Vol 142 (Suppl_4) ◽  
Author(s):  
Bo Zhang ◽  
Kai Chen ◽  
Zhongjie Sun

A disintegrin and metalloproteinase 17 (ADAM17) is a ubiquitously expressed membrane-bound sheddase that cleaves a diverse variety of membrane-bound molecules, including cytokines, growth factors, and their receptors to activate or inactivate various cellular signaling pathways. Although it was reported that ADAM17 may mediate renal diseases, the role of ADAM17 in the regulation of normal kidney function has never been identified. The objective of this study is to investigate whether renal ADAM17 plays a role in maintaining normal kidney function and structure. Tamoxifen-inducible kidney-specific cre (Ksp) and ADAM17-floxed mice were cross-bred for generating Ksp/ADAM17-floxed mice. Injection of tamoxifen initiated deletion of the ADAM17 gene in renal tubule cells. We found that conditional kidney-specific knockout of ADAM1 7 gene (Ksp-ADAM17 -/-) decreased urinary creatinine and sodium excretion were decreased in Ksp-ADAM17 -/- mice, indicating that ADAM17 gene deficiency impairs kidney function. H&E staining showed glomerulus collapse and tubule dilation in Ksp-ADAM17 -/- mice. The epithelial cells fall off into the lumen in the renal tubule. Mesangial expansion and fibrosis were found in glomeruli in Ksp-ADAM17 -/- mice. Moreover, apoptosis was increased in tubule cells in both cortex and medulla areas in Ksp-ADAM17 -/- mice. In conclusion, ADAM17 is critical to the maintenance of normal renal function and structure.


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