Phosphorylation of zona occludens-2 by protein kinase C epsilon regulates its nuclear exportation

Mol Biol Cell. 2009 Sep;20(18):4120-9. doi: 10.1091/mbc.e08-11-1129. Epub 2009 Jul 22.

Abstract

Here, we have analyzed the subcellular destiny of newly synthesized tight junction protein zona occludens (ZO)-2. After transfection in sparse cells, 74% of cells exhibit ZO-2 at the nucleus, and after 18 h the value decreases to 17%. The mutation S369A located within the nuclear exportation signal 1 of ZO-2 impairs the nuclear export of the protein. Because Ser369 represents a putative protein kinase C (PKC) phosphorylation site, we tested the effect of PKC inhibition and stimulation on the nuclear export of ZO-2. Our results strongly suggest that the departure of ZO-2 from the nucleus is regulated by phosphorylation at Ser369 by novel PKCepsilon. To test the route taken by ZO-2 from synthesis to the plasma membrane, we devised a novel nuclear microinjection assay in which the nucleus served as a reservoir for anti-ZO-2 antibody. Through this assay, we demonstrate that a significant amount of newly synthesized ZO-2 goes into the nucleus and is later relocated to the plasma membrane. These results constitute novel information for understanding the mechanisms that regulate the intracellular fate of ZO-2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus / drug effects
  • Animals
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Cell Nucleus / drug effects
  • Cell Nucleus / enzymology*
  • Dogs
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects
  • Epithelial Cells / enzymology
  • Fatty Acids, Unsaturated / pharmacology
  • Immunoprecipitation
  • Membrane Proteins / biosynthesis
  • Membrane Proteins / metabolism*
  • Mutant Proteins / metabolism
  • Phosphorylation / drug effects
  • Phosphoserine / metabolism
  • Protein Binding / drug effects
  • Protein Kinase C-epsilon / antagonists & inhibitors
  • Protein Kinase C-epsilon / metabolism*
  • Protein Kinase Inhibitors / pharmacology
  • Time Factors
  • Transfection
  • Zonula Occludens-2 Protein

Substances

  • Fatty Acids, Unsaturated
  • Membrane Proteins
  • Mutant Proteins
  • Protein Kinase Inhibitors
  • Zonula Occludens-2 Protein
  • Phosphoserine
  • Protein Kinase C-epsilon
  • leptomycin B