beta 2-syntrophin and Par-3 promote an apicobasal Rac activity gradient at cell-cell junctions by differentially regulating Tiam1 activity

Research output: Contribution to journalArticle


Although Rac and its activator Tiam1 are known to stimulate cell-cell adhesion, the mechanisms regulating their activity in cell-cell junction formation are poorly understood. Here, we identify beta 2-syntrophin as a Tiam1 interactor required for optimal cell-cell adhesion. We show that during tight-junction (TJ) assembly beta 2-syntrophin promotes Tiam1-Rac activity, in contrast to the function of the apical determinant Par-3 whose inhibition of Tiam1-Rac activity is necessary for TJ assembly. We further demonstrate that beta 2-syntrophin localizes more basally than Par-3 at cell-cell junctions, thus generating an apicobasal Rac activity gradient at developing cell-cell junctions. Targeting active Rac to TJs shows that this gradient is required for optimal TJ assembly and apical lumen formation. Consistently, beta 2-syntrophin depletion perturbs Tiam1 and Rac localization at cell-cell junctions and causes defects in apical lumen formation. We conclude that beta 2-syntrophin and Par-3 fine-tune Rac activity along cell-cell junctions controlling TJ assembly and the establishment of apicobasal polariy.


  • Natalie A. Mack
  • Andrew P. Porter
  • Helen J. Whalley
  • Juliane P. Schwarz
  • Richard C. Jones
  • Azharuddin Sajid Syed Khaja
  • Anders Bjartell
  • Kurt I. Anderson
  • Angeliki Malliri
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cancer and Oncology
  • Urology and Nephrology
Original languageEnglish
Pages (from-to)1169-1180
JournalNature Cell Biology
Issue number11
Publication statusPublished - 2012
Publication categoryResearch