title: Caveolin-1 Deficiency Inhibits the Basolateral K+ Channels in the Distal Convoluted Tubule and Impairs Renal K+ and Mg2+ Transport.
abstract: Kcnj10 encodes the inwardly rectifying K(+) channel Kir4.1 in the basolateral membrane of the distal convoluted tubule (DCT) and is activated by c-Src. However, the regulation and function of this K(+) channel are incompletely characterized. Here, patch-clamp experiments in Kcnj10-transfected HEK293 cells demonstrated that c-Src-induced stimulation of Kcnj10 requires coexpression of caveolin-1 (cav-1), and immunostaining showed expression of cav-1 in the basolateral membrane of parvalbumin-positive DCT. Patch-clamp experiments detected a 40-pS inwardly rectifying K(+) channel, a heterotetramer of Kir4.1/Kir5.1, in the basolateral membrane of the early DCT (DCT1) in both wild-type (WT) and cav-1-knockout (KO) mice. However, the activity of this basolateral 40-pS K(+) channel was lower in KO mice than in WT mice. Moreover, the K(+) reversal potential (an indication of membrane potential) was less negative in the DCT1 of KO mice than in the DCT1 of WT mice. Western blot analysis demonstrated that cav-1 deficiency decreased the expression of the Na(+)/Cl(-) cotransporter and Ste20-proline-alanine-rich kinase (SPAK) but increased the expression of epithelial Na(+) channel-α. Furthermore, the urinary excretion of Mg(2+) and K(+) was significantly higher in KO mice than in WT mice, and KO mice developed hypomagnesemia, hypocalcemia, and hypokalemia. We conclude that disruption of cav-1 decreases basolateral K(+) channel activity and depolarizes the cell membrane potential in the DCT1 at least in part by suppressing the stimulatory effect of c-Src on Kcnj10. Furthermore, the decrease in Kcnj10 and Na(+)/Cl(-) cotransporter expression induced by cav-1 deficiency may underlie the compromised renal transport of Mg(2+), Ca(2+), and K(+).
authors.affiliation: Department of Physiology, Harbin Medical University, Harbin, China; Department of Pharmacology, New York Medical College, Valhalla, New York; and wenhui_wang@nymc.edu.
authors.forename: Lijun
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York; and Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College, Xuzhou, China.
authors.forename: Chengbiao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York; and.
authors.forename: Xiaotong
authors.initials: X
authors.lastname: Su
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York; and.
authors.forename: Dao-Hong
authors.initials: DH
authors.lastname: Lin
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, New York; and wenhui_wang@nymc.edu.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Wang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D051242:Caveolin 1 / Q000235:genetics / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D004573:Electrolytes; D005260:Female; D053579:Gitelman Syndrome / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007008:Hypokalemia / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism*; D014162:Transfection; D000098854:Kcnj10 Channel
chemical_list: C495540:CAV1 protein, human; C495541:Cav1 protein, mouse; D051242:Caveolin 1; D004573:Electrolytes; D000098854:Kcnj10 Channel; D024661:Potassium Channels, Inwardly Rectifying; D049452:Green Fluorescent Proteins; D008274:Magnesium; D011188:Potassium; D002118:Calcium
keywords: Gitelman’s syndrome; K channels; hypokalemia
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