Generation and analyses of R8L barttin knockin mouse

Naohiro Nomura, Masato Tajima, Noriko Sugawara, Tetsuji Morimoto, Yoshiaki Kondo, Mayuko Ohno, Keiko Uchida, Kerim Mutig, Sebastian Bachmann, Manoocher Soleimani, Eriko Ohta, Akihito Ohta, Eisei Sohara, Tomokazu Okado, Tatemitsu Rai, Thomas J. Jentsch, Sei Sasaki, Shinichi Uchida

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

Barttin, a gene product of BSND, is one of four genes responsible for Bartter syndrome. Coex-pression 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 β-subunit remaining bound to ClC-K ct-subunits (Hayama A, Rai T, Sasaki S, Uchida S. Histochem Cell Biol 119: 485-493, 2003). 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 diseaselike 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.

Original languageEnglish
Pages (from-to)F297-F307
JournalAmerican Journal of Physiology - Renal Physiology
Volume301
Issue number2
DOIs
Publication statusPublished - 2011 Aug

Keywords

  • Bartter syndrome
  • Clc chloride channel
  • Microperfusion

ASJC Scopus subject areas

  • Physiology
  • Urology

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