Disease-causing mutant WNK4 increases paracellular chloride permeability and phosphorylates claudins
| Autor: | Tatemitsu Rai, Kozue Yamauchi, Eisei Sohara, Tomohiro Itoh, Tatsunori Suzuki, Atsushi Hayama, Shinichi Uchida, Katsuki Kobayashi, Shin Suda, Sei Sasaki |
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| Rok vydání: | 2004 |
| Předmět: |
Cell Membrane Permeability
Mutant Protein Serine-Threonine Kinases Biology Kidney Cell Line Tight Junctions Dogs Chlorides Animals Humans RNA Messenger Cloning Molecular Phosphorylation Claudin Multidisciplinary Tight junction Reverse Transcriptase Polymerase Chain Reaction urogenital system Sodium Membrane Proteins WNK Lysine-Deficient Protein Kinase 1 Biological Sciences WNK1 Molecular biology WNK4 Paracellular transport Mutagenesis Site-Directed ROMK |
| Zdroj: | Proceedings of the National Academy of Sciences. 101:4690-4694 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.0306924101 |
| Popis: | Mutations in the WNK4 gene cause pseudohypoaldosteronism type II (PHAII), an autosomal-dominant disorder of hyperkalemia and hypertension. The target molecules of this putative kinase and the molecular mechanisms by which the mutations cause the phenotypes are currently unknown. Although recent reports found that expression of WNK4 in Xenopus oocytes causes inhibition of the thiazide-sensitive NaCl cotransporter and the renal K channel ROMK, there may be additional targets of WNK4. For example, an increase in paracellular chloride permeability has been postulated to be a mediator of PHAII pathogenesis, a possibility supported by the localization of WNK4 at tight junctions in vivo . To determine the validity of this hypothesis, we measured transepithelial Na and Cl permeability in Madin-Darby canine kidney II cells stably expressing wild-type or a pathogenic mutant of WNK4. We found that transepithelial paracellular Cl permeability was increased in cells expressing a disease-causing mutant WNK4 (D564A) but that Na permeability was decreased slightly. Furthermore, WNK4 bound and phosphorylated claudins 1-4, major tight-junction membrane proteins known to be involved in the regulation of paracellular ion permeability. The increases in phosphorylation of claudins were greater in cells expressing the mutant WNK4 than in cells expressing wild-type protein. These results clearly indicate that the pathogenic WNK4 mutant possesses a gain-of-function activity and that the claudins may be important molecular targets of WNK4 kinase. The increased paracellular “chloride shunt” caused by the mutant WNK4 could be the pathogenic mechanism of PHAII. |
| Databáze: | OpenAIRE |
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