Retinal pigment epithelial cells secrete urokinase-type plasminogen activator and its inhibitor PAI-1.
Secretion of plasminogen activators and their inhibitors was examined in cultures of human retinal pigment epithelial (RPE) cells. The methods employed were zymography and reverse zymography, solid-phase immunocapture assay, metabolic labeling followed by immunoprecipitation, and immunofluorescence. The results showed that these cells produce urokinase-type plasminogen activator (u-PA) and a plasminogen activator inhibitor (PAI) which is immunologically and biochemically similar to PAI-1. Tissue-type plasminogen activator activity (t-PA) was not detected, but we detected small amounts of t-PA in an inactive complex with inhibitor in RPE cell-conditioned media. We conclude that RPE cells have the potential to utilize u-PA-catalyzed plasminogen activation which is subject to regulation by PAI-1. These results may have a bearing on the pathogenesis of proliferative retinal diseases.
Sirén
V
V
Department of Virology, University of Helsinki, Finland.
Stephens
R W
RW
Salonen
E M
EM
Vaheri
A
A
Summanen
P
P
Immonen
I
I
D000911:Antibodies, Monoclonal; D002478:Cells, Cultured; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D006801:Humans; D007124:Immunoenzyme Techniques; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism*; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000032:analysis; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D003470:Culture Media; D017395:Plasminogen Activator Inhibitor 1; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator