β-Catenin dynamics in the regulation of microvascular endothelial cell hyperpermeability

Shock. 2012 Mar;37(3):306-11. doi: 10.1097/SHK.0b013e318240b564.

Abstract

β-Catenin, a key regulator of barrier integrity, is an important component of the adherens junctional complex. Although the roles of β-catenin in maintaining the adherens junctions and Wnt signaling are known, the dynamics of β-catenin following insult and its potential role in vascular recovery/repair remain unclear. Our objective was to define β-catenin's dynamics following disruption of the adherens junctional complex and subsequent recovery. Rat lung microvascular endothelial cells were treated with active caspase 3 enzyme, by protein transference method, as an inducer of junctional damage and permeability. The disruption and subsequent recovery of β-catenin to the adherens junctions were studied via immunofluorescence. Rat lung microvascular endothelial cell monolayers were used to measure hyperpermeability. To understand the role of β-catenin on nuclear translocation/transcriptional regulation in relationship to the recovery of the adherens junctions, Tcf-mediated transcriptional activity was determined. Active caspase 3 induced a loss of β-catenin at the adherens junctions at 1 and 2 h followed by its recovery at 3 h. Transference of Bak peptide, an inducer of endogenous caspase 3 activation, induced hyperpermeability at 1 h followed by a significant decrease at 2 h. Inhibition of GSK-3β and the transfection of β-catenin vector increased Tcf-mediated transcription significantly (P < 0.05). The dissociated adherens junctional protein β-catenin translocates into the cytoplasm, resulting in microvascular hyperpermeability followed by a time-dependent recovery and relocation to the cell membrane. Our data suggest a recycling pathway for β-catenin to the cell junction.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adherens Junctions / drug effects*
  • Adherens Junctions / physiology
  • Animals
  • Caspase 3 / metabolism*
  • Cells, Cultured
  • Endothelial Cells / physiology*
  • Endothelium, Vascular / cytology
  • Enzyme Activation
  • Glycogen Synthase Kinase 3 / antagonists & inhibitors
  • Glycogen Synthase Kinase 3 beta
  • Lung / cytology
  • Permeability / drug effects*
  • Protein Transport
  • Rats
  • Transfection
  • bcl-2 Homologous Antagonist-Killer Protein / pharmacology
  • beta Catenin / metabolism*

Substances

  • Bak1 protein, rat
  • bcl-2 Homologous Antagonist-Killer Protein
  • beta Catenin
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, rat
  • Glycogen Synthase Kinase 3
  • Caspase 3