title: Generation and analysis of the thiazide-sensitive Na+ -Cl- cotransporter (Ncc/Slc12a3) Ser707X knockin mouse as a model of Gitelman syndrome.
abstract: Gitelman syndrome (GS) is characterized by salt-losing hypotension, hypomagnesemia, hypokalemic metabolic alkalosis, and hypocalciuria. To better model human GS caused by a specific mutation in the thiazide-sensitive Na(+) -Cl(-) cotransporter (NCC) gene SLC12A3, we generated a nonsense Ncc Ser707X knockin mouse corresponding to human p.Ser710X (c.2135C>A), a recurrent mutation with severe phenotypes in Chinese GS patients. Compared with wild-type or heterozygous littermates, homozygous (Hom) knockin mice fully recapitulated the phenotype of human GS. The markedly reduced Ncc mRNA and virtually absent Ncc protein expression in kidneys of Hom mice was primarily due to nonsense-mediated mRNA decay (NMD) surveillance mechanisms. Expression of epithelial Na(+) channel (Enac), Ca(2+) channels (Trpv5 and Trpv6), and K(+) channels (Romk1 and maxi-K) were significantly increased. Late distal convoluted tubules (DCT) volume was increased and DCT cell ultrastructure appeared intact. High K(+) intake could not correct hypokalemia but caused a further increase in maxi-K but not Romk1 expression. Renal tissue from a patient with GS also showed the enhanced TRPV5 and ROMK1 expression in distal tubules. We suggest that the upregulation of TRPV5/6 and of ROMK1 and Maxi-K may contribute to hypocalciuria and hypokalemia in Ncc Ser707X knockin mice and human GS, respectively.
authors.affiliation: Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Sung-Sen
authors.initials: SS
authors.lastname: Yang
authors.forename: Yi-Fen
authors.initials: YF
authors.lastname: Lo
authors.forename: I-Shing
authors.initials: IS
authors.lastname: Yu
authors.forename: Shu-Wha
authors.initials: SW
authors.lastname: Lin
authors.forename: Tai-Hsiang
authors.initials: TH
authors.lastname: Chang
authors.forename: Yu-Juei
authors.initials: YJ
authors.lastname: Hsu
authors.forename: Tai-Kuang
authors.initials: TK
authors.lastname: Chao
authors.forename: Huey-Kang
authors.initials: HK
authors.lastname: Sytwu
authors.forename: Shinichi
authors.initials: S
authors.lastname: Uchida
authors.forename: Sei
authors.initials: S
authors.lastname: Sasaki
authors.forename: Shih-Hua
authors.initials: SH
authors.lastname: Lin
mesh_terms: D000818:Animals; D001483:Base Sequence; D015220:Calcium Channels / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects; D018389:Codon, Nonsense / Q000235:genetics; D004032:Diet; D004195:Disease Models, Animal; D005260:Female; D005455:Fluorescent Antibody Technique; D055879:Gene Knock-In Techniques / Q000379:methods*; D053579:Gitelman Syndrome / Q000235:genetics* / Q000473:pathology; D006801:Humans; D007668:Kidney / Q000187:drug effects / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008875:Middle Aged; D008969:Molecular Sequence Data; D010641:Phenotype; D011189:Potassium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D020871:RNA Stability / Q000187:drug effects / Q000235:genetics; D011955:Receptors, Drug / Q000235:genetics* / Q000378:metabolism; D012694:Serine / Q000235:genetics*; D012964:Sodium / Q000378:metabolism; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters / Q000235:genetics* / Q000378:metabolism; D049971:Thiazides / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D015220:Calcium Channels; D018389:Codon, Nonsense; D011955:Receptors, Drug; C578874:SLC12A3 protein, human; C578875:Slc12a3 protein, mouse; D064486:Solute Carrier Family 12, Member 3; D027981:Symporters; D049971:Thiazides; D012694:Serine; D011189:Potassium Chloride; D012964:Sodium