DIFFERENTIAL EXPRESSION OF CATHEPSIN-B AND CATHEPSIN-D IN TESTIS AND EPIDIDYMIS OF ADULT-RATS

Cathepsins are specific proteases in lysosomes that participate in the degradation of proteins, some of which are derived from endocytosis. In this study we examined the immunocytochemical localization of cathe psin B and D antibodies in cells of rat testis and epididymis, using l ight and electron microscopic immunocytochemistry. In testis, cathepsi n D was immunolocalized over lysosomes of Sertoli cells and Leydig cel ls and on the acrosome of spermatids. Cathepsin B was found over lysos omes of macrophages. Non-ciliated cells of the efferent ducts revealed intense immunogold labeling over lysosomes with both anti-cathepsin B and D antibodies. In epididymis, cathepsins B and D showed marked var iations in expression over the different epithelial cells and regional differences for a given cell type. Anti-cathepsin D antibodies showed intense labeling over lysosomes of principal cells in the corpus and proximal cauda. In contrast, anticathepsin B antibodies revealed inten sely labeled lysosomes of principal cells of the distal initial segmen t, intermediate zone, and caput epididymidis, with weaker labeling in other regions. Clear cells of the proximal caput epididymidis revealed intensely labeled lysosomes for anti-cathepsin D antibodies. In the d istal caput, dear cells showed a variable reaction pat;tern from inten sely labeled to unreactive. Basal tells of the intermediate zone and p roximal caput region were intensely reactive for anti-cathepsin D anti bodies. There was no staining over dear or basal cells with anti-cathe psin B antibodies. Taken together, these results demonstrate cell-spec ific and regional differences in the distribution of cathepsins B and D in cells of the male reproductive system. Such results suggest subst rate specificity with regard to protein turnover within lysosomes of c ells of testis and epididymis.