抄録
Plasminogen activator (PA) is the enzyme converting plasminogen to its active form, plasmin, involved in various physiological and pathological phenomena. The conversion is catalyzed by two types of PA, urokinase-type PA (uPA) and tissue-type PA (tPA). When human dental pulp cells were stimulated by the inflammatory cytokine tumor necrosis factor–α (TNF-α), PA activity in the conditioned medium was increased, indicating that TNF-α provoked PA secretion. The TNF-α–induced PA release was significantly enhanced in the presence of phorbol-12-myristate-13-acetate (PMA), a protein kinase C (PKC) activator. The PKC inhibitor Ro31-8220 abolished the effect of PMA on the PA release. The activity of PA secreted from the cells stimulated by TNF-α and PMA was reduced by immunoprecipitation using anti-uPA antibody. PMA failed to enhance TNF-α–induced expression of uPA mRNA. These results suggest that protein kinase C synergistically enhances secretion of uPA in TNF-α–stimulated human dental pulp cells.
