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Am J Physiol Renal Physiol. 2021;320(4):F559-F568.

Soluble α-klotho anchors TRPV5 to the distal tubular cell membrane independent of FGFR1 by binding TRPV5 and galectin-1 simultaneously.

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제1저자 이진호 · 교신저자 오국환

소속 (8)
  1. Center of Medical Innovation, Seoul National University Hospital, Seoul, Korea.
  2. Department of Internal Medicine, Pusan National University Hospital, Busan, Korea.
  3. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
  4. Department of Internal Medicine, Ewha Womans University Seoul Hospital, Ewha Womans University College of Medicine, Seoul, South Korea.
  5. Transplantation Research Institute, Seoul National University Hospital, Seoul, Korea.
  6. Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea.
  7. Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea.
  8. Kidney Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea.

Abstract

Hypercalciuria is one of the early manifestations of diabetic nephropathy (DN). This is partially due to a decrease in the expression of renal transient receptor potential vanilloid type 5 (TRPV5), which is responsible for renal Ca2+ reabsorption. Soluble klotho has been previously determined to increase TRPV5 by cleaving sialic acid, causing TRPV5 to bind to membrane protein galectin-1. However, a recent study showed that soluble klotho binds to α2-3-sialyllactose, where sialic acid is located, on TRPV5, rather than cleave it. Here, we report that soluble klotho tethers TRPV5 on the membrane by binding both TRPV5 and galectin-1, thereby protecting membrane TRPV5 from diabetes-induced endocytosis. In the present study, we injected recombinant soluble α-klotho protein (rKL) into db/db and db/m mice for 8 wk and collected urine and kidneys. We administered rKL, AZD4547 [fibroblast growth factor (FGF) receptor type 1 inhibitor], and OTX008 (galectin-1 inhibitor) to cultured mouse distal tubular cells with or without 30 mM high-glucose (HG) exposure. db/db mice showed increased renal Ca2+ excretion and decreased renal TRPV5 expression. rKL treatment reversed this change. In vitro, TRPV5 expression in distal tubular cells decreased under HG conditions, and rKL successfully upregulated TRPV5 with or without FGF23. Also, immunofluorescence showed colocalization of klotho, TRPV5, and galectin-1 in distal tubule cells, suggesting that klotho binds to both TRPV5 and galectin-1. Moreover, when both FGF receptor type 1 and galectin-1 were inhibited, rKL failed to increase TRPV5 under HG conditions. Our results indicate that soluble klotho prevents TRPV5 from degradation and subsequent diabetes-induced endocytosis by anchoring TRPV5 through binding with both TRPV5 and galectin-1.NEW & NOTEWORTHY Soluble α-klotho anchors transient receptor potential vanilloid type 5 (TRPV5) on the apical membrane of the distal tubule by binding both TRPV5 and a membrane-abundant protein, galectin-1. This newly discovered mechanism works even when fibroblast growth factor (FGF)23 signaling is inhibited by treatment with FGF receptor type 1 inhibitor. Therefore, we identified how soluble α-klotho increases TRPV5 without FGF23. We confirmed this mechanism by observing that soluble α-klotho fails to enhance TRPV5 when both FGF receptor type 1 and galectin-1 are inhibited.

Keywords

diabetic nephropathygalectin-1hypercalciuriatransient receptor potential vanilloid type 5α-klotho

그 밖의 정보
출판 형태
Journal Article, Research Support, Non-U.S. Gov't
저널
American journal of physiology. Renal physiology · eISSN 1522-1466
전자 출판
2021-02-22
MeSH
Animals · Benzamides / pharmacology · Calcium Channels / drug effects / metabolism · Cell Membrane / drug effects / metabolism · Diabetic Nephropathies / metabolism · Endocytosis / drug effects / physiology · Epithelial Cells / metabolism · Fibroblast Growth Factor-23 · Fibroblast Growth Factors / metabolism · Galectin 1 / metabolism / pharmacology · Kidney / metabolism · Mice · N-Acetylneuraminic Acid / pharmacology · Piperazines / pharmacology · Pyrazoles / pharmacology · TRPV Cation Channels / drug effects / metabolism
Substances
AZD4547 · Benzamides · Calcium Channels · Fgf23 protein, mouse · Galectin 1 · Piperazines · Pyrazoles · TRPV Cation Channels · Trpv5 protein, mouse · Fibroblast Growth Factors · Fibroblast Growth Factor-23 · N-Acetylneuraminic Acid