Identification of endothelial cell binding sites on the laminin gamma 1 chain

The laminins belong to a family of trimeric basement membrane glycoproteins with multiple domains, structures, and functions. Endothelial cells bind l aminin-1 and form capillary-like structures when plated on a laminin-1-rich basement membrane matrix, Matrigel. Laminin-1 is composed of 3 chains, alp ha 1, beta 1, and gamma 1. Because laminin-1 is known to contain multiple b iologically active sites, we have screened 156 synthetic overlapping peptid es spanning the entire laminin gamma 1 chain for potential angiogenic seque nces. Only 7 of these peptides, designated as C16, C25, C30, C38, C64, C75, and C102, disrupted the formation of capillary-like structures by human um bilical vein endothelial cells on Matrigel. Dose-response experiments in th e presence of 50 to 200 mu g/mL showed that tube formation was prevented by most peptides at 150 and 200 mu g/mL, except for C16, which showed strong activity at all concentrations. Active peptides promoted vessel sprouting f rom aorta rings and angiogenesis in the chick chorioallantoic membrane assa y. In addition, the active peptides also promoted endothelial cell adhesion to dishes coated with 0.1 mu g of peptide and inhibited attachment to lami nin-1 but not to plastic or fibronectin. Four of the active peptides, C25, C38, C75, and C102, may have cell-type specificity with endothelial cells, since they did not promote PC12 neurite outgrowth or adhesion of B16-F10 me lanoma and human submandibular gland cells. These results suggest that spec ific laminin gamma 1-chain peptides have angiogenic activity with potential therapeutic applications.