Generation and analyses of R8L barttin knockin mouse

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Item Type:	Article
Title:	Generation and analyses of R8L barttin knockin mouse
Creators Name:	Nomura, N., Tajima, M., Sugawara, N., Morimoto, T., Kondo, Y., Ohno, M., Uchida, K., Mutig, K., Bachmann, S., Soleimani, M., Ohta, E., Ohta, A., Sohara, E., Okado, T., Rai, T., Jentsch, T.J., Sasaki, S. and Uchida, S.
Abstract:	Barttin, a gene product of BSND, is one of four genes responsible for Bartter syndrome. Co-expression of barttin with ClC-K chloride channels dramatically induces the expression of ClC-K current via insertion of ClC-K-barttin complexes into plasma membranes. We previously showed that stably expressed R8L barttin, a disease-causing missense mutant, is retained in the endoplasmic reticulum (ER) of Madin-Darby Canine Kidney (MDCK) cells with the barttin beta-subunit remaining bound to ClC-K alpha-subunits. However, transient expression of R8L barttin in MDCK cells was reported to impair ClC-K channel function without affecting its subcellular localization. To investigate the pathogenesis in vivo, we generated a knockin mouse model of Bartter syndrome that carries the R8L mutation. These mice display disease-like phenotypes (hypokalemia, metabolic alkalosis, and decreased NaCl reabsorption in distal tubules) under a low-salt diet. Immunofluorescence and immunoelectron microscopy revealed that the plasma membrane localization of both R8L barttin and the ClC-K channel was impaired in these mice, and transepithelial chloride transport in the thin ascending limb of Henle's loop (tAL) as well as thiazide-sensitive chloride clearance were significantly reduced. This reduction in transepithelial chloride transport in tAL, which is totally dependent on ClC-K1/barttin, correlated well with the reduction in the amount of R8L barttin localized to plasma membranes. These results suggest that the major cause of Bartter syndrome type IV caused by R8L barttin mutation is its aberrant intracellular localization.
Keywords:	CLC Chloride Channel, Bartter Syndrome, Microperfusion, Animals, Mice, Animal Disease Models, Chloride Channels, Furosemide, Gene Knock-In Techniques, Loop of Henle, Membrane Proteins, Missense Mutation, Perfusion, Phenotype, Sodium Channels, Sodium Chloride Symporter Inhibitors, Sodium Potassium Chloride Symporter Inhibitors, Transgenic Mice
Source:	American Journal of Physiology Renal Physiology
ISSN:	1931-857X
Publisher:	American Physiological Society
Volume:	301
Number:	2
Page Range:	F297-F307
Date:	August 2011
Official Publication:	https://doi.org/10.1152/ajprenal.00604.2010
PubMed:	View item in PubMed

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