Selective expression and processing of biglycan during migration of bovine aortic endothelial cells. The role of endogenous basic fibroblast growth factor.

Repair of the vascular lumenal surface after injury requires a controlled endothelial cell response that includes cell migration, proliferation, and remodeling of the extracellular matrix. These cellular processes are modulated by growth factors that are released or activated following cell injury. When endothelial cell migration is stimulated in response to monolayer wounding in vitro, cells increase synthesis of small leucine-rich dermatan sulfate proteoglycans (PGs) (Kinsella, M. G., and Wight, T. N. (1986) J. Cell Biol. 102, 679-687). However, the identity of the PGs that are increased during cell migration and the factors that affect this modulation have not been identified. We now report that basic fibroblast growth factor (bFGF) is responsible for the transient increase of [35S]sulfate incorporation into PGs following monolayer wounding. SDS-polyacrylamide gel electrophoresis analysis revealed that bFGF-treated and wounded cultures increase both biglycan core protein synthesis and biglycan proteolytic processing, which results in the accumulation of a approximately 20-kDa N-terminal biglycan fragment in the culture media. Biglycan RNA steady-state levels also selectively increase 2- to 3-fold after wounding or bFGF treatment. Finally, immunocytochemical staining localizes biglycan to the tips and edges of lamellopodia on migrating cells, indicating that biglycan is found at loci at which the formation and dissolution of adhesion plaques occurs, consistent with hypotheses that predict involvement of biglycan in the control of cell migration. Taken together, these results suggest that release of endogenous bFGF is primarily responsible for altered biglycan expression, synthesis, and proteolytic processing as endothelial cells migrate after wounding.