Hyaluronectin binds to laminin and blocks laminin-dependent process formation by astrocytes

The interaction of hyaluronectin (HN), a hyaluronic acid-binding extracellular matrix (ECM) glycoprotein with two other ECM-associated molecules, laminin and fibronectin, was studied by ligand blot and solid phase ligand binding assays. Ligand blot analysis with biotin-labeled HN revealed a strong binding of HN to immobilized laminin and a weaker binding to fibronectin. Ligand binding studies indicated a concentration dependent, Ca(2+)-independent binding of HN to laminin. Binding of HN to laminin but not to fibronectin was resistant to increased salt concentrations indicating a non-electrostatic, protein-protein interaction of HN with laminin. The functional relevance of HN-laminin interaction was demonstrated by an inhibition of laminin-supported astroglial process formation by HN.