Expression and distribution of symplekin regulates the assembly and function of the epithelial tight junction

Histochem Cell Biol. 2012 Mar;137(3):319-27. doi: 10.1007/s00418-011-0906-z. Epub 2012 Jan 5.

Abstract

Symplekin is multifunctional protein localized to both the tight junction and the nucleus with known roles in mRNA polyadenylation, proliferation, differentiation and tumorigenesis. Functions of symplekin at tight junctions have not been systematically investigated. In this study, increased expression of symplekin was observed during the formation of tight junctions in cultured HT-29 and HepG2 epithelial cells. Repression of symplekin by RNAi increased the permeability of epithelial monolayers, disrupted cellular polarity, and decreased the expression of the tight junction protein ZO-1. Moreover, symplekin was co-localized with ZO-1 at tight junctions and co-immunoprecipitated with ZO-1, indicating that ZO-1 and symplekin form complexes. In conclusion, symplekin expression regulates the assembly of tight junctions, thus helps to maintain the integrity of the epithelial monolayer and cellular polarity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Caco-2 Cells
  • Cell Division / physiology
  • Cell Membrane Permeability / physiology
  • Cell Polarity / physiology*
  • Down-Regulation / physiology
  • Epithelial Cells / cytology
  • Epithelial Cells / physiology*
  • Gene Expression / physiology
  • HT29 Cells
  • Hep G2 Cells
  • Humans
  • Membrane Proteins / metabolism
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism*
  • Phosphoproteins / metabolism
  • Tight Junctions / physiology*
  • Zonula Occludens-1 Protein

Substances

  • Membrane Proteins
  • Nuclear Proteins
  • Phosphoproteins
  • SYMPK protein, human
  • TJP1 protein, human
  • Zonula Occludens-1 Protein