Hyaluronan-binding protein in endothelial cell morphogenesis

Previous studies from several laboratories have provided evidence that interaction of hyaluronan (HA) with the surface of endothelial cells may be involved in endothelial cell behavior. We have recently characterized a mAb, mAb IVd4, that recognizes and neutralizes HA- binding protein (HABP) from a wide variety of cell types from several different species (Banerjee, S. D., and B. P. Toole. 1991. Dev. Biol. 146:186-197). In this study we have found that mAb IVd4 inhibits migration of endothelial cells from a confluent monolayer after "wounding" of the monolayer. HA hexasaccharide, a fragment of HA with the same disaccharide composition as polymeric HA, also inhibits migration. In addition, both reagents inhibit morphogenesis of capillary-like tubules formed in gels consisting of type I collagen and basement membrane components. Immunocytology revealed that the antigen recognized by mAb IVd4 becomes localized to the cell membrane of migrating cells, including many of their lamellipodia. Treatment with high concentrations of HA hexamer causes loss of immunoreactivity from these structures. We conclude that HABP recognized by mAb IVd4 is involved in endothelial cell migration and tubule formation.