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Panel of monoclonal antibodies – alternative tool For monitoring of sperm–zona pellucida receptors localization and identification
Zigo, Michal ; Dorosh, Andriy ; Pohlová, Alžběta ; Jonáková, Věra ; Šulc, Miroslav ; Maňásková-Postlerová, Pavla
Primary binding of the sperm to the zona pellucida (ZP) is one of the many steps necessary for successful fertilization in all sexually reproducing species. Sperm bind ZP by means of membrane receptors which recognize carbohydrate moieties on ZP glycoproteins according to a well-precised sequential process. Primary-binding receptors are localized throughout the acrosomal region of the sperm surface of which many have been disclosed in various mammals. For the monitoring sperm-zona pellucida receptors in terms of localization and characterization - panel of monoclonal antibodies against proteins from the sperm surface was prepared. Antibodies were screened by immunofluorescence and Western blotting for protein localizations and competence of antibodies, respectively. Antibodies recognizing proteins localized on the sperm head and simultaneously detected by Western blot were further studied by means of immunolocalization in reproductive tissues and fluids, binding to ZP, immunoprecipitation and protein identification using MS analysis. Out of 17 prepared antibodies, 8 antibodies were simultaneously recognizing proteins localized on the sperm head and detecting proteins of interest by Western blotting. Further only 3 antibodies recognized proteins which also coincided in binding to ZP. These 3 antibodies were used for immunoprecipitation, and further protein identification of immunoprecipitates revealed that the antibodies distinguish acrosin precursor, RAB2A protein, and lactadherin P47. Acrosin and lactadherin P47 have been already detected on the sperm surface and their physiological functions in reproduction have been proposed. To our knowledge, this is the first time RAB2A has been found on the surface of sperm and its physiological function in the process of fertilization remains undisclosed.
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Enzymatic and inhibiting activity in boar epididymal fluid
Davidová, Nina ; Ren, Š. ; Liberda, J. ; Jonáková, Věra ; Maňásková-Postlerová, Pavla
Sperm maturation, represents a key step in the reproduction process. Spermatozoa, particularly the plasma membrane, are exposed to epididymal fluid (EF) components representing the natural environment essential for their post-testicular maturation. Changes in the sperm membrane proteins are influenced by proteolytic and glycosidic enzymes present in the EF. Accordingly, the occurrence of inhibitors in this reproductive organ is very important for the regulation of sperm membrane protein processing. In present study, we monitored protease and glycosidase activities, and inhibitors of metallo- and serine proteinases in boar EF. Additionally, we studied acrosin inhibitor in fluid, spermatozoa and tissue along the epididymis. We chromatographically separated boar EF into several fractions. These fractions were subjected to SDS-electrophoresis and the separated proteins were either studied by zymographic methods or transferred to nitrocellulose membranes for detection of metallo- and serine proteinases and their inhibitors, and acrosin inhibitor by specific antibody, respectively. Acrosin inhibitor was monitored also in the sperm and tissue of the boar epididymis. In boar epididymal fluid, several metallo- and serine proteinases with different molecular masses, and inhibitors of metalloproteinase MMP-9 and acrosin were found. We measured strong activity of mannosidase in this fluid. Using specific antibody, we registered the increasing signal of acrosin inhibitor from caput to cauda epididymis in the spermatozoa, fluid and also tissue. Proteinases and their inhibitors in reproductive fluids may play a significant role in reproduction processes. Especially, acrosin inhibitor in the reproductive tract inactivates prematurely released sperm acrosin and protects spermatozoa and reproductive epithelium against proteolytic degradation. High mannosidase activity in boar EF suggests evident role of mannose structures in the sperm interaction during reproductive events.
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