Expression of urokinase type plasminogen activator receptor (uPAR) in the bovine oviduct: Relationship with uPA effect on oviductal epithelial cells

• uPAR and uPA are expressed in bovine oviduct during the estrous cycle.
• uPAR localizes at the apical zone of epithelial cells in vivo and in vitro.
• uPA stimulation increases c-fos expression in oviductal cell cultures.
• uPA/uPAR binding would activate signaling pathways regulating oviductal function.

Urokinase type plasminogen activator (uPA) is an oviductal fluid component whose activity is regulated by binding to urokinase type plasminogen activator receptor (uPAR). In this study uPAR and uPA gene expression in bovine oviduct were evaluated and similar expression patterns for both uPAR and uPA mRNAs were observed during the estrous cycle. Immunolocalization of uPAR at the apical zone of epithelial cells suggests that uPA action would be focalized in the oviductal lumen, triggering intracellular signaling pathways. As uPAR expression was also observed in in vitro cultures of oviductal epithelial cells, the effect of uPA was explored using this culture model. Real-time RT-PCR demonstrated that c-fos expression in oviductal cell cultures increases under uPA stimulation. These results suggest that uPA/uPAR binding would be involved in signaling pathways that activate transcription factors and would regulate the synthesis of molecules concerned with the arrangement of a particular oviductal microenvironment.