| First Author | Wolf MT | Year | 2013 |
| Journal | Kidney Int | Volume | 84 |
| Issue | 1 | Pages | 130-7 |
| PubMed ID | 23466996 | Mgi Jnum | J:318139 |
| Mgi Id | MGI:6858400 | Doi | 10.1038/ki.2013.63 |
| Citation | Wolf MT, et al. (2013) Uromodulin upregulates TRPV5 by impairing caveolin-mediated endocytosis. Kidney Int 84(1):130-7 |
| abstractText | Uromodulin (UMOD) is synthesized in the thick ascending limb and secreted into urine as the most abundant protein. Association studies in humans suggest protective effects of UMOD against calcium-containing kidney stones. Mice carrying mutations of Umod found in human UMOD-associated kidney disease (UAKD) and Umod-deficient mice exhibit hypercalciuria. The mechanism for UMOD regulation of urinary Ca(2+) excretion is incompletely understood. We examined if UMOD regulates TRPV5 and TRPV6, channels critical for renal transcellular Ca(2+) reabsorption. Coexpression with UMOD increased whole-cell TRPV5 current density in HEK293 cells. In biotinylation studies, UMOD increased TRPV5 cell-surface abundance. Extracellular application of purified UMOD upregulated TRPV5 current density within physiological relevant concentration ranges. UMOD exerted a similar effect on TRPV6. TRPV5 undergoes constitutive caveolin-mediated endocytosis. UMOD had no effect on TRPV5 in a caveolin-1-deficient cell line. Expression of recombinant caveolin-1 in these cells restored the ability of UMOD to upregulate TRPV5. Secretion of UAKD-mutant UMOD was markedly reduced and coexpression of mutant UMOD with TRPV5 failed to increase its current. Immunofluorescent studies demonstrated lower TRPV5 expression in Umod(-/-) mice compared with wild-type. UMOD upregulates TRPV5 by acting from extracellular and by decreasing endocytosis of TRPV5. The stimulation of Ca(2+) reabsorption via TRPV5 by UMOD may contribute to protection against kidney-stone formation. |
