title: Pendrin gene ablation alters ENaC subcellular distribution and open probability.
abstract: The present study explored whether the intercalated cell Cl(-)/HCO3(-) exchanger pendrin modulates epithelial Na(+) channel (ENaC) function by changing channel open probability and/or channel density. To do so, we measured ENaC subunit subcellular distribution by immunohistochemistry, single channel recordings in split open cortical collecting ducts (CCDs), as well as transepithelial voltage and Na(+) absorption in CCDs from aldosterone-treated wild-type and pendrin-null mice. Because pendrin gene ablation reduced 70-kDa more than 85-kDa γ-ENaC band density, we asked if pendrin gene ablation interferes with ENaC cleavage. We observed that ENaC-cleaving protease application (trypsin) increased the lumen-negative transepithelial voltage in pendrin-null mice but not in wild-type mice, which raised the possibility that pendrin gene ablation blunts ENaC cleavage, thereby reducing open probability. In mice harboring wild-type ENaC, pendrin gene ablation reduced ENaC-mediated Na(+) absorption by reducing channel open probability as well as by reducing channel density through changes in subunit total protein abundance and subcellular distribution. Further experiments used mice with blunted ENaC endocytosis and degradation (Liddle's syndrome) to explore the significance of pendrin-dependent changes in ENaC open probability. In mouse models of Liddle's syndrome, pendrin gene ablation did not change ENaC subunit total protein abundance, subcellular distribution, or channel density, but markedly reduced channel open probability. We conclude that in mice harboring wild-type ENaC, pendrin modulates ENaC function through changes in subunit abundance, subcellular distribution, and channel open probability. In a mouse model of Liddle's syndrome, however, pendrin gene ablation reduces channel activity mainly through changes in open probability.
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia;
authors.forename: Vladimir
authors.initials: V
authors.lastname: Pech
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Department of Physiology, Emory University School of Medicine, Atlanta, Georgia; and smwall@emory.edu.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Wall
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia;
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nanami
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, Georgia; and.
authors.forename: Hui-Fang
authors.initials: HF
authors.lastname: Bao
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia;
authors.forename: Young Hee
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia;
authors.forename: Yoskaly
authors.initials: Y
authors.lastname: Lazo-Fernandez
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, Georgia; and.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yue
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia;
authors.forename: Truyen D
authors.initials: TD
authors.lastname: Pham
authors.affiliation: Department of Physiology, Emory University School of Medicine, Atlanta, Georgia; and.
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Eaton
authors.affiliation: Department of Medicine, University of Florida, Gainesville, Florida.
authors.forename: Jill W
authors.initials: JW
authors.lastname: Verlander
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins / Q000502:physiology*; D004195:Disease Models, Animal; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D005260:Female; D007685:Kidney Tubules, Collecting / Q000502:physiology*; D056929:Liddle Syndrome / Q000235:genetics / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012964:Sodium / Q000378:metabolism*; D000076988:Sulfate Transporters; D014357:Trypsin
chemical_list: D027321:Anion Transport Proteins; D053503:Epithelial Sodium Channels; C494849:Slc26a4 protein, mouse; D000076988:Sulfate Transporters; D012964:Sodium; D014357:Trypsin
keywords: epithelial sodium channel; pendrin