Apical scaffolding protein NHERF2 modulates the localization of alternatively spliced plasma membrane Ca2+ pump 2B variants in polarized epithelial cells

J Biol Chem. 2010 Oct 8;285(41):31704-12. doi: 10.1074/jbc.M110.164137. Epub 2010 Jul 27.

Abstract

The membrane localization of the plasma membrane Ca(2+)-ATPase isoform 2 (PMCA2) in polarized cells is determined by alternative splicing; the PMCA2w/b splice variant shows apical localization, whereas the PMCA2z/b and PMCA2x/b variants are mostly basolateral. We previously reported that PMCA2b interacts with the PDZ protein Na(+)/H(+) exchanger regulatory factor 2 (NHERF2), but the role of this interaction for the specific membrane localization of PMCA2 is not known. Here we show that co-expression of NHERF2 greatly enhanced the apical localization of GFP-tagged PMCA2w/b in polarized Madin-Darby canine kidney cells. GFP-PMCA2z/b was also redirected to the apical membrane by NHERF2, whereas GFP-PMCA2x/b remained exclusively basolateral. In the presence of NHERF2, GFP-PMCA2w/b co-localized with the actin-binding protein ezrin even after disruption of the actin cytoskeleton by cytochalasin D or latrunculin B. Surface biotinylation and fluorescence recovery after photobleaching experiments demonstrated that NHERF2-mediated anchorage to the actin cytoskeleton reduced internalization and lateral mobility of the pump. Our results show that the specific interaction with NHERF2 enhances the apical concentration of PMCA2w/b by anchoring the pump to the apical membrane cytoskeleton. The data also suggest that the x/b splice form of PMCA2 contains a dominant lateral targeting signal, whereas the targeting and localization of the z/b form are more flexible and not fully determined by intrinsic sequence features.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Alternative Splicing / drug effects
  • Alternative Splicing / physiology*
  • Animals
  • Bridged Bicyclo Compounds, Heterocyclic / pharmacology
  • Cell Membrane / metabolism*
  • Cell Polarity / physiology*
  • Cytochalasin D / pharmacology
  • Cytoskeletal Proteins / metabolism
  • Cytoskeleton / metabolism
  • Dogs
  • Epithelial Cells / metabolism*
  • HeLa Cells
  • Humans
  • Isoenzymes / genetics
  • Isoenzymes / metabolism
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Plasma Membrane Calcium-Transporting ATPases / genetics
  • Plasma Membrane Calcium-Transporting ATPases / metabolism*
  • Protein Structure, Tertiary
  • Protein Transport / drug effects
  • Protein Transport / physiology
  • Sodium-Hydrogen Exchangers / genetics
  • Sodium-Hydrogen Exchangers / metabolism*
  • Thiazolidines / pharmacology

Substances

  • Actins
  • Bridged Bicyclo Compounds, Heterocyclic
  • Cytoskeletal Proteins
  • Isoenzymes
  • Nucleic Acid Synthesis Inhibitors
  • Phosphoproteins
  • Sodium-Hydrogen Exchangers
  • Thiazolidines
  • ezrin
  • sodium-hydrogen exchanger regulatory factor
  • Cytochalasin D
  • Plasma Membrane Calcium-Transporting ATPases
  • ATP2B2 protein, human
  • latrunculin B