The transport of Cathepsin D in rat epididymal cells

BANNOUD N; AGUILERA AC; SOSA MA; CARVELLI L

Mendoza

Congreso; XXVIII Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2010

Sociedad de Biología de Cuyo

The epididymal epithelium secretes proteins into the lumen, some of which are acid hydrolases (such as cathepsin D). In other cell types, hydrolytic enzymes are transported to lysosomes mediated by receptors for mannose-6-phosphate, the cation-dependent and independent ones (CI-CD and MPRS). In some cellular models, procatepsin D (PCD) is complexed with prosaposin (SAP), which are transported to lysosomes or secreted by sortilin (Sort). Here, we have attempted to identify the transport pathway for PCD (CD-MPR and / or Sort) in epididymal cells and how it could be regulated by steroid hormones. We evaluated the expression and secretion of PCD and SAP, and the expression of CD-MPR and Sort in RCE-1 line cells (rat epididymis), subjected to hormone treatments (estradiol or tamoxifen), and in the presence or absence of NH4Cl. The proteins under study were detected by immunoblot from cells or culture medium. Estradiol induced an increase in the expression and secretion of PCD, but no changes in the expression of Sort or the CD-MPR. In turn, treatment with NH4Cl decreased the secretion of PCD, with greater intracellular retention, accompanied by an increase in the expression of Sort and CD-MPR. These preliminary results suggest that PCD is not secreted by "default" in the presence of estradiol and that an alternative route of transport, mediated by Sort and regulated by estrogen may be involved.