Ultrastructural Localization of the Prostasome - an Organelle in Human Seminal Plasma

Abstract

Secretory granules and vesicles were demonstrated within human prostatic cells and in the acinar lumen. In size and ultrastructure the granules and vesicles were the same as those previously isolated from human prostatic fluid and seminal plasma. "Prostasomes" is suggested as the designation for these secretory granules and vesicles. As a rule they were found in storage vesicles within the secretory cells. Two mechanisms for translocation of the prostasomes from the cell interior to the acinar lumen are described. One mechanism involves exocytosis with binding of storage vesicles to, and fusion with the plasma membrane, resulting in release of prostasomes directly into the acinar lumen. The other mechanism implies displacement of storage vesicles in toto from the cell interior to the acinar lumen. This process differs from exocytosis and is here designated "diacytosis". Both phenomena appear to be of roughly equal frequency.

Expression of Prostasome-like Granules by the Prostate Cancer Cell Lines PC3, Dul45 and LnCaP Grown in Monolayer

“…The general morphology of the growing monolayers was similar to that reported by others (3, 4, The prostasomes, which are observed by electron microscopy to appear in storage vesicles of the prostate epithelial cells, are small secretory granules or vesicles with an average size of 100-150 nm (1). The monoclonal antibody mAb78, which was raised against prostasomes purified from the seminal plasma, was tentatively assumed to visualize prostasomes but it also cross-reacted with, among other structures, liver cells, pancreatic endocrine cells, and macrophages (7).…”

Differentiation of Human Prostate Cancer PC-3 Cells Induced by Inhibitors of Inosine 5′-Monophosphate Dehydrogenase

“…cles termed prostasomes (12). To characterize the protein composition of these organelles, Renneberg et al (47) performed a two-dimensional gel electrophoresis analysis and established the presence of 80 distinct protein entities, which were not well characterized.…”

“…Secretory cells of the mature prostate contain highly organized organelles called prostasomes (12), which are released into the prostate fluid and semen (13). These organelles contain in their membrane a variety of proteins including complement regulators CD46 (14), CD55, and CD59 (15), an essential cofactor for coagulation, tissue factor (16), and several peptidase activities, including dipeptidyltranspeptidase/CD26 (17), neutral endopeptidase/CD10 (18), aminopeptidase N/CD13 (19), ␥-glutamyltranspeptidase (20), and aminopeptidase P (21).…”

Proteomic Analysis of Microvesicles Released by the Human Prostate Cancer Cell Line PC-3

“…The microvesicles pelleted at 100,000 ϫ g from the culture medium of these cells have previously been referred as prostasomes (8,29), a term used to name vesicles released by prostate cells (30,31). There is strong evidence that most microvesicles released from PC-3 cells are secreted in a similar way as exosomes (8,29).…”