title: β-Catenin dynamics in the regulation of microvascular endothelial cell hyperpermeability.
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.
authors.affiliation: Department of Surgery, Texas A&M Health Science Center College of Medicine and Scott & White Memorial Hospital, Temple, Texas 76508, USA.
authors.forename: Binu
authors.initials: B
authors.lastname: Tharakan
authors.forename: Joseph
authors.initials: J
authors.lastname: Hellman
authors.forename: Devendra A
authors.initials: DA
authors.lastname: Sawant
authors.forename: John H
authors.initials: JH
authors.lastname: Tinsley
authors.forename: Alan R
authors.initials: AR
authors.lastname: Parrish
authors.forename: Felicia A
authors.initials: FA
authors.lastname: Hunter
authors.forename: W Roy
authors.initials: WR
authors.lastname: Smythe
authors.forename: Ed W
authors.initials: EW
authors.lastname: Childs
mesh_terms: D022005:Adherens Junctions / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D053148:Caspase 3 / Q000378:metabolism*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000502:physiology*; D004730:Endothelium, Vascular / Q000166:cytology; D004789:Enzyme Activation; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors; D000071679:Glycogen Synthase Kinase 3 beta; D008168:Lung / Q000166:cytology; D010539:Permeability / Q000187:drug effects*; D021381:Protein Transport; D051381:Rats; D014162:Transfection; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000494:pharmacology; D051176:beta Catenin / Q000378:metabolism*
chemical_list: C494774:Bak1 protein, rat; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051176:beta Catenin; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D038362:Glycogen Synthase Kinase 3; D053148:Caspase 3