Plasmin-induced Migration Requires Signaling through Protease-activated Receptor 1 and Integrin α9β1

Abstract

Plasmin is a major extracellular protease that elicits intracellular signals to mediate platelet aggregation, chemotaxis of peripheral blood monocytes, and release of arachidonate and leukotriene from several cell types in a G protein-dependent manner. Angiostatin, a fragment of plasmin(ogen), is a ligand and an antagonist for integrin ␣ 9 ␤ 1 . Here we report that plasmin specifically interacts with ␣ 9 ␤ 1 and that plasmin induces migration of cells expressing recombinant ␣ 9 ␤ 1 (␣ 9 -Chinese hamster ovary (CHO) cells). Migration was dependent on an interaction of the kringle domains of plasmin with ␣ 9 ␤ 1 as well as the catalytic activity of plasmin. Angiostatin, representing the kringle domains of plasmin, alone did not induce the migration of ␣ 9 -CHO cells, but simultaneous activation of the G protein-coupled protease-activated receptor (PAR)-1 with an agonist peptide induced the migration on angiostatin, whereas PAR-2 or PAR-4 agonist peptides were without effect. Furthermore, a small chemical inhibitor of PAR-1 (RWJ 58259) and a palmitoylated PAR-1-blocking peptide inhibited plasmin-induced migration of ␣ 9 -CHO cells. These results suggest that plasmin induces migration by kringle-mediated binding to ␣ 9 ␤ 1 and simultaneous proteolytic activation of PAR-1.

The Lymphangiogenic Vascular Endothelial Growth Factors VEGF-C and -D Are Ligands for the Integrin α9β1

“…The ␣9␤1 integrin has now been described to interact with a relatively large number of ligands including tenascin C, osteopontin, vascular cell adhesion molecule-1, coagulation factor XIII, and several members of the ADAMs family of transmembrane metalloproteinases (7,24,(45)(46)(47). The biological significance of ␣9␤1 interactions with most of these ligands remains to be determined.…”

Plasminogen/Plasmin Modulates Bone Metabolism by Regulating the Osteoblast and Osteoclast Function

“…Furthermore, inhibitors of JAK, p38 MAPK, and NF-B revealed that these signaling pathways are indispensable for the plasmin-mediated tumor necrosis factor-␣ and IL-6 induction in the cells. In addition, angiostatin, a fragment of plasmin(ogen), is a ligand and an antagonist for integrin ␣9␤1 (27). Angiostatin, representing the kringle domains of plasmin, alone did not induce the migration of Chinese hamster ovary (CHO) cells, but simultaneous activation of the G protein-coupled protease-activated receptor-1 with an agonist peptide induced the migration on angiostatin.…”

Plasmin Induces In Vivo Monocyte Recruitment through Protease-Activated Receptor-1–, MEK/ERK-, and CCR2-Mediated Signaling

“…1D, 1F) with U0126, an MEK/ERK inhibitor, abolished the Pla-induced migration. Although Pla is a known in vitro inducer of cell migration of both cells types used in the present study, fibroblasts (22), and monocytes/macrophages (17, 31), we applied a different migration assay to validate the data obtained from the scratch assay, because it could be difficult to differentiate between migration and proliferation. By using a chemotaxis assay we were also able to observe that U0126 efficiently decreased macrophage migration (Fig.…”

“…Some of these effects are followed by the activation of the transcription factors NF-kB and AP-1 (16)(17)(18)(19). Pla also triggers multiple signaling pathways such as JAK/STAT, p38 MAPK, and ERK1/2 (18)(19)(20) and it has been shown to activate protease-activated receptor-1 (PAR-1) in fibroblasts (21,22). We have previously demonstrated that the proinflammatory cytokine IFN-a increased the expression of the Plg receptor a-enolase on the surface of human monocytes with a consequent increase of Pla generation and proteolysis (23).…”