title: Urokinase synthesis and binding by glomerular epithelial cells in culture.
abstract: Fibrin deposits are frequently observed in the course of proliferative extracapillary glomerulonephritis and could be related to a defective local fibrinolysis. We studied human glomerular epithelial cells in culture which were found to release mainly a urokinase-type plasminogen activator (u-PA) identified on zymography by its molecular weight (53 kD), its plasminogen activator activity, and its neutralization by specific polyclonal anti-u-PA IgG. Trace amounts of tissue-type plasminogen activator (t-PA) complexed to a plasminogen activator inhibitor type 1 (PAI-1) were identified with specific antibodies. Specific binding sites were found at the surface of glomerular epithelial cells (kD: 2.10(-9) M), partially occupied by secreted u-PA. The spontaneous u-PA activity of the culture medium conditioned by glomerular epithelial cells was very low, suggesting that u-PA was released in its inactive single chain proenzyme form (SC-u-PA). After activation of SC-u-PA by plasmin, u-PA activity of the culture medium was found to increase in a time- and dose-dependent manner when cells were incubated with phorbol myristic acetate (PMA). This effect was inhibited by H7, a protein kinase C inhibitor. Stimulation of u-PA synthesis by PMA was also observed in two different epithelial tubular cell lines. LLC-PK1 and MDCK cells. However, 8 bromo cyclic AMP which increased u-PA release by LLC-PK1 cells was found to inhibit u-PA release by PMA-stimulated glomerular epithelial cells and MDCK cells. By Northern blot analysis we found that PMA induced an increase of u-PA mRNA level in glomerular epithelial cells and that cyclic AMP had an opposite effect.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: INSERM, Unité 64, Hôpital Tenon, Paris, France.
authors.forename: E
authors.initials: E
authors.lastname: Rondeau
authors.forename: S
authors.initials: S
authors.lastname: Ochi
authors.forename: R
authors.initials: R
authors.lastname: Lacave
authors.forename: C J
authors.initials: CJ
authors.lastname: He
authors.forename: R
authors.initials: R
authors.lastname: Medcalf
authors.forename: F
authors.initials: F
authors.lastname: Delarue
authors.forename: J D
authors.initials: JD
authors.lastname: Sraer
mesh_terms: D015152:Blotting, Northern; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology; D004792:Enzyme Precursors / Q000096:biosynthesis* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000378:metabolism*; D010960:Plasminogen Activators / Q000096:biosynthesis* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D004792:Enzyme Precursors; C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D000242:Cyclic AMP; D010960:Plasminogen Activators; D014568:Urokinase-Type Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate