1. Phosphorylated claudin-16 interacts with Trpv5 and regulates transcellular calcium transport in the kidney.
- Author
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Hou J, Renigunta V, Nie M, Sunq A, Himmerkus N, Quintanova C, Bleich M, Renigunta A, and Wolf MTF
- Subjects
- Animals, Calcium Channels genetics, Cell Membrane Permeability, Claudins antagonists & inhibitors, Claudins genetics, HEK293 Cells, Humans, Male, Mice, Mice, Knockout, Phosphorylation, TRPV Cation Channels antagonists & inhibitors, TRPV Cation Channels genetics, Calcium metabolism, Calcium Channels metabolism, Claudins metabolism, Kidney Tubules, Distal metabolism, TRPV Cation Channels metabolism, Tight Junctions metabolism, Transcytosis
- Abstract
Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) was previously considered to be a paracellular channelopathy caused by mutations in the claudin-16 and claudin-19 genes. Here, we provide evidence that a missense FHHNC mutation c.908C>G (p.T303R) in the claudin-16 gene interferes with the phosphorylation in the claudin-16 protein. The claudin-16 protein carrying phosphorylation at residue T303 is localized in the distal convoluted tubule (DCT) but not in the thick ascending limb (TAL) of the mouse kidney. The phosphomimetic claudin-16 protein carrying the T303E mutation but not the wildtype claudin-16 or the T303R mutant protein increases the Trpv5 channel conductance and membrane abundance in human kidney cells. Phosphorylated claudin-16 and Trpv5 are colocalized in the luminal membrane of the mouse DCT tubule; phosphomimetic claudin-16 and Trpv5 interact in the yeast and mammalian cell membranes. Knockdown of claudin-16 gene expression in transgenic mouse kidney delocalizes Trpv5 from the luminal membrane in the DCT. Unlike wildtype claudin-16, phosphomimetic claudin-16 is delocalized from the tight junction but relocated to the apical membrane in renal epithelial cells because of diminished binding affinity to ZO-1. High-Ca
2+ diet reduces the phosphorylation of claudin-16 protein at T303 in the DCT of mouse kidney via the PTH signaling cascade. Knockout of the PTH receptor, PTH1R, from the mouse kidney abrogates the claudin-16 phosphorylation at T303. Together, these results suggest a pathogenic mechanism for FHHNC involving transcellular Ca2+ pathway in the DCT and identify a molecular component in renal Ca2+ homeostasis under direct regulation of PTH., Competing Interests: The authors declare no conflict of interest.- Published
- 2019
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