Na+/H+ exchanger regulatory factor 1 overexpression-dependent increase of cytoskeleton organization is fundamental in the rescue of F508del cystic fibrosis transmembrane conductance regulator in human airway CFBE41o- cells

Mol Biol Cell. 2010 Jan 1;21(1):73-86. doi: 10.1091/mbc.e09-03-0185. Epub 2009 Nov 4.

Abstract

We have demonstrated that Na(+)/H(+) exchanger regulatory factor 1 (NHERF1) overexpression in CFBE41o- cells induces a significant redistribution of F508del cystic fibrosis transmembrane conductance regulator (CFTR) from the cytoplasm to the apical membrane and rescues CFTR-dependent chloride secretion. Here, we observe that CFBE41o- monolayers displayed substantial disassembly of actin filaments and that overexpression of wild-type (wt) NHERF1 but not NHERF1-Delta Ezrin-Radixin-Moesin (ERM) increased F-actin assembly and organization. Furthermore, the dominant-negative band Four-point one, Ezrin, Radixin, Moesin homology (FERM) domain of ezrin reversed the wt NHERF1 overexpression-induced increase in both F-actin and CFTR-dependent chloride secretion. wt NHERF1 overexpression enhanced the interaction between NHERF1 and both CFTR and ezrin and between ezrin and actin and the overexpression of wt NHERF1, but not NHERF1-DeltaERM, also increased the phosphorylation of ezrin in the apical region of the cell monolayers. Furthermore, wt NHERF1 increased RhoA activity and transfection of constitutively active RhoA in CFBE41o- cells was sufficient to redistribute phospho-ezrin to the membrane fraction and rescue both the F-actin content and the CFTR-dependent chloride efflux. Rho kinase (ROCK) inhibition, in contrast, reversed the wt NHERF1 overexpression-induced increase of membrane phospho-ezrin, F-actin content, and CFTR-dependent secretion. We conclude that NHERF1 overexpression in CFBE41o- rescues CFTR-dependent chloride secretion by forming the multiprotein complex RhoA-ROCK-ezrin-actin that, via actin cytoskeleton reorganization, tethers F508del CFTR to the cytoskeleton stabilizing it on the apical membrane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Animals
  • Bronchi / cytology*
  • Cell Line
  • Chlorides / metabolism
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism*
  • Cytoskeletal Proteins / metabolism
  • Cytoskeleton / metabolism*
  • Endocytosis
  • Epithelial Cells / cytology
  • Epithelial Cells / metabolism*
  • Humans
  • Kinetics
  • Membrane Proteins / metabolism
  • Mice
  • Microfilament Proteins / metabolism
  • Phosphoproteins / metabolism*
  • Protein Binding
  • Protein Transport
  • Signal Transduction
  • Sodium-Hydrogen Exchangers / metabolism*
  • rho-Associated Kinases / metabolism
  • rhoA GTP-Binding Protein / metabolism

Substances

  • Actins
  • Chlorides
  • Cytoskeletal Proteins
  • Membrane Proteins
  • Microfilament Proteins
  • Phosphoproteins
  • Sodium-Hydrogen Exchangers
  • cystic fibrosis transmembrane conductance regulator delta F508
  • ezrin
  • sodium-hydrogen exchanger regulatory factor
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • moesin
  • radixin
  • rho-Associated Kinases
  • rhoA GTP-Binding Protein