Beta-arrestin-dependent Parathyroid Hormone-stimulated Extracellular Signal-regulated Kinase Activation and Parathyroid Hormone Type 1 Receptor Internalization.
From: Department of Pharmacology, Renal Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
Endocrinology
- Publish Date: Aug 2007
- ISSN: 0013-7227
- Volume: 148
- Issue: 8
- Pages: 4073-9
- Medium: Print
- Language: English
- Citation (JAMA): Sneddon W Bruce, Friedman Peter A, et al. Beta-arrestin-dependent Parathyroid Hormone-stimulated Extracellular Signal-regulated Kinase Activation and Parathyroid Hormone Type 1 Receptor Internalization.. Endocrinology Aug 2007;148:4073-9
Abstract
PTH regulates renal calcium homeostasis by actions on the distal nephron. PTH-induced calcium transport in mouse distal convoluted tubule (DCT) cells requires activation of ERK1/2. ERK activation by beta-adrenergic receptors occurs in a biphasic manner and involves receptor internalization. An early rapid phase is beta-arrestin (betaAr) independent, whereas prolonged activation is betaAr dependent. We characterized PTH-stimulated ERK activation and the involvement of receptor internalization and betaAr dependence. In DCT cells, PTH transiently activated ERK maximally at 5 min and then returned to baseline. betaAr dependence of PTH receptor (PTH1R)-mediated ERK stimulation was assessed using mouse embryonic fibroblasts (MEFs) from betaAr1- and -2-null mice. In wild-type MEFs, PTH(1-34)-stimulated ERK activation peaked after 5 min, was 50% maximal after 15 min, and then recovered to 80% of maximal stimulation by 30 min. In MEFs null for betaAr1 and -2, PTH-stimulated ERK activation peaked by 5 min and returned to baseline. The effect was identical in betaAr2-null MEFs. In betaAr1-null MEFs, ERK exhibited delayed activation and remained elevated. PTH-stimulated ERK activation and receptor endocytosis were not inhibited by the clathrin-binding domain of betaAr1 [Ar(319-418)]. Coexpression of the sodium proton exchanger regulatory factor 1 (NHERF1) with Ar(319-418) blocked PTH1R internalization. We conclude that PTH-stimulated ERK activation in DCT cells proceeds with a rapid but transient phase that may involve betaAr1. Furthermore, the betaAr-dependent late phase of ERK activation by PTH requires the participation of betaAr2 and PTH1R internalization.
Mesh Headings (Keywords): Animals, Arrestins, Calcium, Cells, Cultured, Endocytosis, Fibroblasts, Kidney Tubules, Distal, Mice, Mice, Mutant Strains, Mitogen-Activated Protein Kinase 1, Mitogen-Activated Protein Kinase 3, Parathyroid Hormone, Phosphorylation, Receptor, Parathyroid Hormone, Type 1, Signal Transduction
Check for Full Text / PubMed Unique Identifier (PMID): 17525124
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