Papers In Press, published online ahead of print May 3, 2006
J. Biol. Chem, 10.1074/jbc.M512771200
Submitted on November 29, 2005
Revised on April 12, 2006
Accepted on April 13, 2006
Opposing roles of ZYXIN/LPP ACTA repeats and the LIM domain region in cell-cell adhesion
Marc D. H. Hansen and Mary C. Beckerle
Physiology and Developmental Biology, Brigham Young University, Provo, UT 84602
Corresponding Author: marchansen{at}byu.edu
Cadherins mediate cell-cell adhesion by linking cell junctions to actin networks. Though several actin regulatory systems have been implicated in cell-cell adhesion, it remains unclear how such systems drive cadherin-actin network formation and how they are regulated to coincide with initiation of adhesion. Previous work implicated VASP in assembly of cell-cell junctions in keratinocytes and the VASP binding protein zyxin colocalizes with VASP at cell-cell junctions. Here we examine how domains in zyxin and its relative LPP contribute to cell-cell junction assembly. Using a quantitative assay for cell-cell adhesion, we demonstrate that zyxin and LPP function to increase the rate of early cell-cell junction assembly through the VASP-binding ActA repeat region. We also identify the LIM region of zyxin and LPP to be a regulatory domain that blocks function of these proteins. Deletion of the LIM domains drives adhesion and increases VASP level in detergent insoluble cadherin-actin. Dominant-negative zyxin/LPP mutants reduce the rate of adhesion, lower VASP levels in detergent insoluble cadherin-actin networks, and allow for the accumulation of capping protein at cell-cell contacts. These data implicate the LIM domains of zyxin and LPP in regulating cell-cell junction assembly through VASP.