UROKINASE‐INDUCED SMOOTH MUSCLE CELL MIGRATION REQUIRES PKC‐alpha AND PKC‐delta ISOFORMS

Abstract

Purpose: To determine a role for protein kinase C in urokinase (uPA)-induced smooth muscle cell (SMC) migration, and to examine specific kinase pathways that may act downstream of PKC to influence the response of SMCs to uPA. Background: Vascular SMC migration is an important component of the development of intimal hyperplasia. During tissue remodeling, uPA is one of the key serine proteases involved and stimulates SMC migration in vitro. Methods: Rat arterial SMCs were cultured in vitro. Linear wound and Boyden microchemotaxis assays of migration were performed in the presence of uPA (1–100 nM) with and without general PKC inhibitor, GF109203X (GFX, 1–10 nM), PKC-alpha inhibitor, Goe6976 (1μM) and PKC-delta inhibitor, rottlerin (3μM). Western blotting was performed for phosphorylated and total MEK1/2 and ERK1/2 after stimulation with uPA (10nM) with and without PKC inhibitors. Results: uPA stimulated migration of SMCs in both the linear wound assay (p<0.01) and in the Boyden chamber (p<0.01). PKC-alpha and PKC-delta were the abundant isozymes in the VSMC. Inhibition of PKC with GFX resulted in a concentration dependent decrease in migration in response to uPA. Specific inhibition of PKC-alpha and PKC-delta resulted in ~ 30% decrease in migration (p<0.05). uPA stimulated phosphorylation of MEK1/2 and ERK1/2 (2-fold increase over control for both, p<0.05). These responses were inhibited by the presence of GFX and were dependent on both PKC-alpha and PKC-delta (p<0.01). Conclusions: uPA-induced SMC migration is PKC dependent and is due to their regulation of MEK1/2 and ERK1/2. Both PKC-alpha and PKC-delta isoforms are involved. Understanding the basic mechanisms of cell migration will allow therapeutic intervention for restenosis.