Urokinase (u-PA) is produced by collecting duct principal cells and is post-transcriptionally regulated by SV40 large-T, arginine vasopressin, and epidermal growth factor.
We have analyzed the expression and regulation of plasminogen activators (PA) in principal cells of the renal collecting duct. We used a rabbit principal cell line (RC.SVtsA58) infected with the temperature-sensitive SV40 strain tsA58. Transformed cells cultured at permissive temperature (33 degrees C) produced only tissue-type plasminogen activator (t-PA). Shifting the cells to nonpermissive temperature (39.5 degrees C) induced their differentiation and a marked increase in total fibrinolytic activity due to the induction of urokinase-type plasminogen activator (u-PA) synthesis and secretion. The effect on u-PA was post-transcriptional and it could be attributed to large-T inactivation at 39.5 degrees C since it was abolished by re-infecting the cells with wild-type SV40. Run-on assay and real-time RT-PCR of u-PA transcripts indicated that large-T altered post-transcriptional regulation. u-PA was also produced by primary cultures of collecting duct cells and was present in the rabbit urine. In the kidney, u-PA and its receptor (u-PAR) were almost exclusively expressed at the apex of collecting duct cells. We then analyzed the regulation of u-PA by arginine vasopressin (AVP) and epidermal growth factor (EGF), two key regulators of principal cell functions. We found that AVP and EGF, which have opposite hydro-osmotic effects in the collecting duct, also exhibited contrasted effects on u-PA synthesis in differentiated RC.SVtsA58 cells. EGF increased but AVP suppressed u-PA activity and protein, and these regulations occurred at post-transcriptional level. These results point to a physiological role of u-PA in principal cells of the renal collecting duct.
Piedagnel
Rémi
R
INSERM, U702, University Pierre et Marie Curie, and Hôpital Tenon, Paris, France. remi.piedagnel@tnn.ap-hop-paris.fr
Tiger
Yoann
Y
Lelongt
Brigitte
B
Ronco
Pierre M
PM
D000818:Animals; D000957:Antigens, Viral, Tumor / Q000494:pharmacology*; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D008024:Ligands; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator; D013539:Simian virus 40 / Q000276:immunology; D010959:Tissue Plasminogen Activator / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*
D000957:Antigens, Viral, Tumor; D008024:Ligands; D017395:Plasminogen Activator Inhibitor 1; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D001127:Arginine Vasopressin; D004815:Epidermal Growth Factor; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator