An Mg2+ and Ca2+-Stimulated Adenosine Triphosphatase in Human Prostatic Fluid - Part II*

Abstract

DiscussionWe have found a specific Mg2+ and Ca'+-dependent ATPase of human prostatic fluid. This activity was recovered after differential centrifugation in a scanty pellet (pellet 11), containing secretory granules and vesicles as revealed by electron microscopy. A further evidence for the structural linkage of the ATPase activity to these membraneous structures was the density gradient centrifugation of pellet I1 (see Fig. 1). This prostatic fluid ATPase hydrolyzes off the terminal phosphate in ATP, thus giving rise to ADP and orthophosphate. Such a reaction is exergonic with a A G' of about -7 kcal/mole. Because of the exergonic character of the reaction and the structural linkage of the enzyme we postulate that a coupling may exist between the ATP hydrolysis and energy requiring reactions in the prostatic gland. Such a coupling may be chemo-mechanical or chemo-osmotic. In the first case a transduction of chemical energy into mechanical work is possible. In the second case a transduction may occur into osmotic work, i.e. transfer across a cell membrane of ions usually against an electrochemical gradient or sometimes against at least an apparent gradienti.e. a chemical gradient.Since the prostate gland is exocrine, the complex mechanisms underlying the exocytosis might be mediated through ATP, thus providing the link between cellular metabolism of the prostate gland and the energy requiring reactionseither contractile processes involving the microfilaments or microtubular system, or active ion movements such as Ca-ions of the secretory cells of the prostate gland.The secretory granules of pellet I1 as shown here may be derived from the Golgi complex (Helminen and Ericsson -1970;Brody et al. -1977). The exocytotic events underlying the exocrine function have particularly been studied in the pancreas (Jamieson and Palade -1971 ;Satir -1974;Singh and Webster -1976). The entire Golgi apparatus of cells from this gland has been claimed (Singh and Webster -1976) to be involved in the processing of secretory proteins, which are then transported through the Golgi vesicles nearest the endoplasmic reticulum. Such transport requires energy, which most probably is supplied by ATP (Jamieson and Palade -1968). The Golgi vesicles are considered to be transformed into secretory granules (Singh and Webster -1976). Such granules of the pancreatic cells can further on, after cholinergic stimulation, move towards and fuse with the plasma membrane. This process, generally called "exocytosis" 'is energy-dependent and Ca'+-dependent in the pancreatic exocrine cells (Jamieson and Palade -1971). *Part I see andrologia 10, 261-272 (1978).

Multiple recognition assay reveals prostasomes as promising plasma biomarkers for prostate cancer

“…The first cellular system to be explored in this regard was the prostate acinar cells. Ronquist et al showed more than 30 y ago that human prostatic fluid and seminal plasma contain membranesurrounded, nanometer-sized microvesicles (7)(8)(9). Subsequent studies revealed that these extracellular microvesicles, now denoted prostasomes, corresponded to intracellular microvesicles inside another larger microvesicle, a so-called storage vesicle, equivalent to multivesicular bodies or late endosomes (10,11).…”

Prostasome Involvement in the Development and Growth of Prostate Cancer~!2009-07-10~!2009-12-09~!2010-02-11~!

“…These secretory cells of the mature prostate contain highly organized organelles named prostasomes [9], which are released into the prostatic fluid and semen by exocytosis [9,52]. This observation of membrane-surrounded prostasomes in an extracellular position [53][54][55] was notable and initially the object of some doubt. The idea of an extracellular occurrence of organellar structures like prostasomes was subsequently corroborated by the demonstration of the extracellular occurrence of exosomes produced by other cell systems [56][57][58][59].…”

“…Protein kinase activity, mainly belonging to the PKA group of enzymes, is associated with prostasomes [89,135]. Prostasomes also show high ATP-cleavage activity which is linked to their membrane [9,54,55]. This cleavage activity is due to the Mg 2+ and Ca 2+ stimulated ATPase enzyme of the prostasomal membrane which is calmodulin-dependent [71].…”

A historical and evolutionary perspective on the biological significance of circulating DNA and extracellular vesicles

“…This stems from three independent factors, namely: (1) most purification regimes cannot completely differentiate between the different EVs; (2) cells release a heterogeneous population of EVs [174][175][176], and (3) there is an overlap in the category of size. For instance, prostasomes (also classified as exosomes) have been documented to range between 40 and 490 nm [177], and some microvesicles have the same sizes as exosomes [178]. In the previous work, we have demonstrated that centrifugation time and speed influence the yield of cfDNA isolated from cell culture media [179].…”

“…Ronquist et al [177] discovered prostasomes in human prostatic fluid and seminal plasma. These vesicles were equivalent to exosomes from other cell types in that they were produced and secreted in the same manner [193].…”