NHERF associations with sodium-hydrogen exchanger isoform 3 (NHE3) and ezrin are essential for cAMP-mediated phosphorylation and inhibition of NHE3.

Published

Journal Article

The sodium-hydrogen exchanger regulatory factor (NHERF) is an essential cofactor for cAMP-mediated inhibition of the Na(+)/H(+) exchanger isoform, NHE3, in renal brush border membranes. NHERF is also an ezrin-binding protein. To define the functional importance of ezrin binding for NHERF's function as a NHE3 regulator, we transfected stable PS120 cells expressing NHE3 with plasmids encoding WT and truncated mouse NHERF proteins. Co-immunoprecipitation established that in PS120 cells, NHE3 bound to full-length NHERF(1-355), the C-terminal domain, NHERF(147-355), and NHERF(1-325), which lacks the proposed ezrin-binding domain. The N-terminal domain, NHERF(1-146), failed to bind the antiporter. Ezrin was also co-immunoprecipitated with NHERF(1-355) but not with NHERF(1-325). 8Br-cAMP inhibited NHE3 activity in cells that expressed NHERF(1-355) or NHERF(147-355) but had no effect on the formation of NHE3-NHERF or NHERF-ezrin complexes. Na(+)/H(+) exchange was unaffected by 8Br-cAMP in cells that expressed NHERF(1-146) or NHERF(1-325). NHE3 phosphorylation in vivo was enhanced by 8Br-cAMP only in cells where NHERF bound to both NHE3 and ezrin. The data suggest that NHERF functions as a scaffold to link NHE3 with ezrin and that this multiprotein complex is essential for cAMP-mediated phosphorylation of NHE3 and the inhibition of Na(+)/H(+) exchange.

Full Text

Duke Authors

Cited Authors

  • Weinman, EJ; Steplock, D; Donowitz, M; Shenolikar, S

Published Date

  • 2000-05-23

Published In

Volume / Issue

  • 39 / 20

Start / End Page

  • 6123 - 6129

PubMed ID

  • 10821685

Pubmed Central ID

  • 10821685

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi000064m

Language

  • eng

Conference Location

  • United States