SORTILIN KNOCK-DOWN AFFECTS THE PROCESSING AND EXPRESSION OF CATHEPSIN D IN EPIDIDYMAL CELLS

ALVAREZ P; LEIVA N; BUTAZZONNI A; SOSA MA; CARVELLI L,; AGUILERA AC

Congreso; Cuyo Biology Society XXXVII; 2019

The intense secretory activity of epididymal cells contributes to sperm maturation. Lysosomal enzymes are highly secreted by theepithelium into the epididymal lumen, and they can participate in remodeling the sperm surface during their maturation process. Inmost eukaryotic cells, the intracellular transport of these enzymes is mostly regulated by mannose 6 phosphate receptors (MPRs).The lysosomal protease cathepsin D (CatD) is mostly transported by MPRs, although the receptor sortilin (Sort) has also beenimplicated in this transport since CatD is complexed with prosaposin (Psap), the natural ligand for Sort. In this study, we evaluatedthe incidence of the Sort expression on transport and processing of CatD in cultured epididymal cells. In a rat epididymal cell line(RCE-1), the sortilin knock-down was induced by transfection with a sortilin pSilencer. Then, we observed by western blot that thisSort silencing increases the expression of other proteins, such as the cation-dependent MPR (CD-MPR) and Psap. In turn, CatD isdecreased under these conditions, where the immature form of the enzyme (proCathepsin D) prevailed. Meanwhile, a similardistribution of wild type RCE-1 was observed by IFI. These preliminary results suggest that proCathepsin D could be transported bysortilin and CD-MPR alternatively, but its processing is affected by the silencing of sortilin in this cell type.