Association of Ezrin with Intercellular Adhesion Molecule-1 and -2 (ICAM-1 and ICAM-2)

Ezrin is a cytoplasmic linker molecule between plasma membrane components and the actin-containing cytoskeleton. We studied whether ezrin is associated with intercellular adhesion molecule (ICAM)-1, -2, and -3. In transfected cells, ICAM-1 and ICAM-2 colocalized with ezrin in microvillar projections, whereas an ICAM-1 construct attached to cell membrane via a glycophosphatidylinositol anchor was uniformly distributed on the cell surface. An interaction of ICAM-2 and ezrin was seen by affinity precipitation, microtiter binding assay, coimmunoprecipitation, and surface plasmon resonance methods. The calculatedK_D value was 3.3 × 10⁻⁷m. Phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P₂) induced an interaction of ezrin and ICAM-1 and enhanced the interaction of ezrin and ICAM-2, but ICAM-3 did not bind ezrin even in the presence of PtdIns(4,5)P₂. PtdIns(4,5)P₂ was shown to bind to cytoplasmic tails of ICAM-1 and ICAM-2, which are the first adhesion proteins demonstrated to interact with PtdIns(4,5)P₂. The results indicate an interaction of ezrin with ICAM-1 and ICAM-2 and suggest a regulatory role of phosphoinositide signaling pathways in regulation of ICAM-ezrin interaction.