Essential role for NHERF in cAMP-mediated inhibition of the Na+-HCO3- co-transporter in BSC-1 cells.

Published

Journal Article

Prior studies have indicated a requirement for the PDZ domain-containing protein, Na(+)/H(+) Exchanger Regulatory Factor (NHERF), for protein kinase A (PKA)-mediated inhibition of the renal basolateral Na(+)-HCO(3)(-) co-transporter (NBC). The present studies explore the potential mechanisms by which NHERF transduces cAMP signals to inhibit NBC. In BSC-1 cells, cells that express NBC but lack NHERF, 8-bromo-cAMP (100 microm for 15 min) failed to inhibit transport until wild-type mNHERF-(1-355) was expressed. mNHERF-(116-355) containing PDZ II and C-terminal ezrin-binding sequences or a mutant unphosphorylated form of rabbit NHERF effectively transduced the cAMP signals that inhibited NBC. By contrast, mNHERF-(1-126) encompassing N-terminal PDZ I and mNHERF-(1-325), which lacks ezrin-binding, failed to support cAMP inhibition of NBC activity. NBC and NHERF did not associate with each other in yeast two-hybrid or co-immunoprecipitation assays, and confocal microscopy indicated distinct subcellular localization of the two proteins. NBC was phosphorylated in BSC-1 cells, but its phosphorylation was not increased by cAMP nor was immunoprecipitated NBC phosphorylated by PKA in vitro. Acute exposure of mNHERF-(1-355)-expressing BSC-1 cells to cAMP did not change cell surface expression of NBC. Although these results established an essential role for NHERF in cAMP-mediated inhibition of NBC in BSC-1 cells, they also suggest a novel mechanism for NHERF-mediated signal transduction distinct from that previously characterized from studies of other NHERF targets.

Full Text

Duke Authors

Cited Authors

  • Weinman, EJ; Evangelista, CM; Steplock, D; Liu, MZ; Shenolikar, S; Bernardo, A

Published Date

  • November 9, 2001

Published In

Volume / Issue

  • 276 / 45

Start / End Page

  • 42339 - 42346

PubMed ID

  • 11535598

Pubmed Central ID

  • 11535598

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M106153200

Language

  • eng

Conference Location

  • United States