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Am J Physiol Renal Physiol. 2011 Jan;300(1):F231-5. doi: 10.1152/ajprenal.00532.2010. Epub 2010 Nov 3.

Dynamics of PTH-induced disassembly of Npt2a/NHERF-1 complexes in living OK cells.

Author information

1
University of Maryland School of Medicine, Department of Veterans Affairs Medical Center, Baltimore, MD 21202, USA. eweinman@medicine.umaryland.edu

Abstract

Parathyroid hormone (PTH) inhibits the reabsorption of phosphate in the renal proximal tubule by disrupting the binding of the sodium-dependent phosphate transporter 2A (Npt2a) to the adapter protein sodium-hydrogen exchanger regulatory factor-1 (NHERF-1), a process initiated by activation of protein kinase C (PKC). To gain additional insights into the dynamic sequence of events, the time course of these responses was studied in living opossum kidney (OK) cells. Using a FRET-based biosensor, we found that PTH activated intracellular PKC within seconds to minutes. In cells expressing GFP-Npt2a and mCherry-NHERF, PTH did not affect the relative abundance of NHERF-1 but there was a significant and time-dependent decrease in the Npt2a/NHERF-1 ratio. The half-time to maximal dissociation was 15 to 20 min. By contrast, PTH had no effect on the fluorescence ratio for GFP-ezrin compared with mCherry-NHERF-1 at the apical surface. These experiments establish that PTH treatment of proximal tubule OK cells leads to rapid activation of PKC with the subsequent dissociation of Npt2a/NHERF-1 complexes. The association of NHERF-1 with Ezrin and their localization at the apical membrane, however, was unperturbed by PTH, thereby enabling the rapid recruitment and membrane reinsertion of Npt2a and other NHERF-1 targets on termination of the hormone response.

PMID:
21048030
PMCID:
PMC3023216
DOI:
10.1152/ajprenal.00532.2010
[Indexed for MEDLINE]
Free PMC Article

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