Immunocytochemical localisation of some lysosomal hydrolases, their presence in luminal fluid and their directional secretion by human epididymal cells in culture

Abstract

The way in which the human epididymis modifies spermatozoa during their sojourn in this structure might be clarified by knowledge of the nature of its secretions. We have examined the presence of several lysosomal hydrolases in human epididymal tissue and fluids, and their synthesis and secretion by monolayer cultures. Tissues were obtained from men undergoing orchidectomy for prostatic carcinoma. The enzymes cathepsin D and acid alpha-glucosidase were localised in the lysosomes of epithelial cells from the corpus epididymidis, by an immunocytochemical technique. Cathepsin D was also found in epithelial cells of the efferent ducts within lysosomes, apical vesicles and multivesicular bodies. No immunolocalisation of acid glucosidase in the efferent ducts or on the microvilli of the corpus was demonstrable. Cathepsin D, beta-hexosaminidase (N-acetylglucosaminidase) and alpha-glucosidase were measurable in the luminal fluid from the human corpus epididymidis; beta-hexosaminidase was secreted into the culture medium by confluent monolayers of epididymal and efferent duct cells. Immunoprecipitation of cell extracts and culture medium of these cultures incubated with 35S-methionine revealed that the precursors of cathepsin D and beta-hexosaminidase were synthesized and secreted by such monolayers. Thus, active lytic enzymes are secreted by the human epididymis and could modify sperm membranes.

A Pre-embedding Technique for Immunocytochemical Visualization of Cathepsin D in Cultured Cells Subjected to Oxidative Stress

“…In the present experiments we applied an immunocytochemical pre-embedding immunogold method to (Ishii et al 1991) and to detect cathepsin D in the lysosomes of human epididymal epithelial cells embedded in Lowicryl K4M (Raczek et al 1995).…”

Identification of HE1 as the Second Gene of Niemann-Pick C Disease

“…2, B and C) indicates that most, if not all, of this protein is located in lysosomes. The abundance of HE1 in epididy-ma1 fluid is not inconsistent with it being a lysosomal protein; epididymal fluid has an acidic milieu (25) and is an abundant source of several other lysosomal proteins (IS, 26,27).…”

Mannose-6-Phosphate Receptors as a Molecular Indicator of Maturation of Epididymal Sperm

“…Both receptors are found in the plasma membrane of rat and human sperm [5,6]. The existence of such MPR s on the sperm surface is still an intriguin g phenomeno n, since most of these receptors (90%) are commonly con® ned to intracellula r membranes in other cell types [17,24,32,64,85].…”

“…The epididymis is particularly rich in acid hydrolases, together with a developed and active lysosomal apparatu s [64,74]. In mice for instance, the highest levels of a-mannosidas e and b-hexosamini dase are expressed in epididymis [31].…”