Deletion of claudin-10 (Cldn10) in the thick ascending limb impairs paracellular sodium permeability and leads to hypermagnesemia and nephrocalcinosis.
In the kidney, tight junction proteins contribute to segment specific selectivity and permeability of paracellular ion transport. In the thick ascending limb (TAL) of Henle's loop, chloride is reabsorbed transcellularly, whereas sodium reabsorption takes transcellular and paracellular routes. TAL salt transport maintains the concentrating ability of the kidney and generates a transepithelial voltage that drives the reabsorption of calcium and magnesium. Thus, functionality of TAL ion transport depends strongly on the properties of the paracellular pathway. To elucidate the role of the tight junction protein claudin-10 in TAL function, we generated mice with a deletion of Cldn10 in this segment. We show that claudin-10 determines paracellular sodium permeability, and that its loss leads to hypermagnesemia and nephrocalcinosis. In isolated perfused TAL tubules of claudin-10-deficient mice, paracellular permeability of sodium is decreased, and the relative permeability of calcium and magnesium is increased. Moreover, furosemide-inhibitable transepithelial voltage is increased, leading to a shift from paracellular sodium transport to paracellular hyperabsorption of calcium and magnesium. These data identify claudin-10 as a key factor in control of cation selectivity and transport in the TAL, and deficiency in this pathway as a cause of nephrocalcinosis.
Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany. t.breiderhoff@mdc-berlin.de
Tilman
T
Breiderhoff
Nina
N
Himmerkus
Marchel
M
Stuiver
Kerim
K
Mutig
Constanze
C
Will
Iwan C
IC
Meij
Sebastian
S
Bachmann
Markus
M
Bleich
Thomas E
TE
Willnow
Dominik
D
Müller
D000818:Animals; D001692:Biological Transport / Q000235:genetics / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D057167:Claudins / Q000235:genetics / Q000378:metabolism*; D004326:Drinking / Q000502:physiology; D053595:Embryonic Stem Cells / Q000502:physiology; D017353:Gene Deletion; D006706:Homeostasis / Q000235:genetics / Q000502:physiology; D008138:Loop of Henle / Q000378:metabolism*; D008274:Magnesium / Q000097:blood*; D008659:Metabolic Diseases / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D051379:Mice; D018345:Mice, Knockout; D009397:Nephrocalcinosis / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D010641:Phenotype; D012964:Sodium / Q000378:metabolism*; D014868:Water Deprivation / Q000502:physiology
D057167:Claudins; C502009:claudin 10; D012964:Sodium; D008274:Magnesium; D002118:Calcium