Defective coupling of apical PTH receptors to phospholipase C prevents internalization of the Na+-phosphate cotransporter NaPi-IIa in Nherf1-deficient mice.

Published

Journal Article

Phosphate reabsorption in the renal proximal tubule occurs mostly via the type IIa Na(+)-phosphate cotransporter (NaP(i)-IIa) in the brush border membrane (BBM). The activity and localization of NaP(i)-IIa are regulated, among other factors, by parathyroid hormone (PTH). NaP(i)-IIa interacts in vitro via its last three COOH-terminal amino acids with the PDZ protein Na(+)/H(+)-exchanger isoform 3 regulatory factor (NHERF)-1 (NHERF1). Renal phosphate reabsorption in Nherf1-deficient mice is altered, and NaP(i)-IIa expression in the BBM is reduced. In addition, it has been proposed that NHERF1 and NHERF2 are important for the coupling of PTH receptors (PTHRs) to phospholipase C (PLC) and the activation of the protein kinase C pathway. We tested the role of NHERF1 in the regulation of NaP(i)-IIa by PTH in Nherf1-deficient mice. Immunohistochemistry and Western blotting demonstrated that stimulation of apical and basolateral receptors with PTH-(1-34) led to internalization of NaP(i)-IIa in wild-type and Nherf1-deficient mice. Stimulation of only apical receptors with PTH-(3-34) failed to induce internalization in Nherf1-deficient mice. Expression and localization of apical PTHRs were similar in wild-type and Nherf1-deficient mice. Activation of the protein kinase C- and A-dependent pathways with 1,2-dioctanoyl-sn-glycerol or 8-bromo-cAMP induced normal internalization of NaP(i)-IIa in wild-type, as well as Nherf1-deficient, mice. Stimulation of PLC activity due to apical PTHRs was impaired in Nherf1-deficient mice. These data suggest that NHERF1 in the proximal tubule is important for PTH-induced internalization of NaP(i)-IIa and, specifically, couples the apical PTHR to PLC.

Full Text

Duke Authors

Cited Authors

  • Capuano, P; Bacic, D; Roos, M; Gisler, SM; Stange, G; Biber, J; Kaissling, B; Weinman, EJ; Shenolikar, S; Wagner, CA; Murer, H

Published Date

  • February 2007

Published In

Volume / Issue

  • 292 / 2

Start / End Page

  • C927 - C934

PubMed ID

  • 16987995

Pubmed Central ID

  • 16987995

International Standard Serial Number (ISSN)

  • 0363-6143

Digital Object Identifier (DOI)

  • 10.1152/ajpcell.00126.2006

Language

  • eng

Conference Location

  • United States