Publications by authors named "Katarina Michalkova"
The important role of extracellular vesicles, which are considered key mediators of intercellular communication under physiological and pathological conditions, in various cellular processes, including those crucial for mammalian reproduction, has been increasingly studied. Tetraspanins, including CD63, are widely used as markers of extracellular vesicles, but they may also play a role in their biogenesis, cargo selection, cell targeting, and uptake. This study aimed to map the journey of the extracellular vesicle protein tetraspanin CD63 from the testis through the epididymis into mature bull sperm via an approach that included immunohistochemistry (immunofluorescence and immunoperoxidase staining), Western blot analysis, and immunoprecipitation analysis.
View Article and Find Full Text PDFMammalian spermatozoa have a surface covered with glycocalyx, consisting of heterogeneous glycoproteins and glycolipids. This complexity arises from diverse monosaccharides, distinct linkages, various isomeric glycans, branching levels, and saccharide sequences. The glycocalyx is synthesized by spermatozoa developing in the testis, and its subsequent alterations during their transit through the epididymis are a critical process for the sperm acquisition of fertilizing ability.
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- Tetraspanin proteins play a crucial role in organizing cellular complexes on the membranes of most nucleated cells, but their specific functions in folliculogenesis and oogenesis in mammals are not fully understood.
- New research has highlighted the distribution of tetraspanins CD9, CD81, CD151, CD82, and CD63 at various stages of follicular development in cattle, indicating possible cooperation between CD9, CD63, and integrin alpha V in ovarian tissues.
- The study also uncovered unique localization patterns of tetraspanins in bovine oocytes and showed that the distribution of these proteins remains unchanged in vitrified oocytes, emphasizing their potential significance in oocyte development and fertilization processes in cattle.
Integrins are transmembrane receptors expressed in all nucleated mammalian cells, critically involved in cell-matrix adhesion and cell-cell interactions that modulate many signalling cascades. It is assumed that integrins also provide essential functions of the reproductive system. In this study, we describe the detailed localization and distribution of αV integrin in the plasma membrane of bull sperm head and tail.
View Article and Find Full Text PDFThe participation of extracellular vesicles in many cellular processes, including reproduction, is unquestionable. Although currently, the tetraspanin proteins found in extracellular vesicles are mostly applied as markers, increasing evidence points to their role in extracellular vesicle biogenesis, cargo selection, cell targeting, and cell uptake under both physiological and pathological conditions. In this review, we bring other insight into the involvement of tetraspanin proteins in extracellular vesicle physiology in mammalian reproduction.
View Article and Find Full Text PDFTetraspanins are multifunctional molecules located in specific microdomains on the plasma membrane. Thanks to their ability to form networks with other proteins they can participate in many cellular functions. Tetraspanins are part of the interactive network in gametes; however, their precise role in fertilization is not yet clear.
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- Phosphorylation and dephosphorylation are key modifications that regulate protein activity in eukaryotic cells, particularly in mature spermatozoa, which cannot produce new proteins.
- The study examined tyrosine phosphorylation in bull spermatozoa from different epididymal regions, revealing some differences in phosphorylation patterns based on antibody specificity and the location of the sperm.
- Overall, the research consistently showed an increase in tyrosine phosphorylation of proteins during the maturation process of bull sperm in the epididymis, supported by various experimental methods.
Article Synopsis
- Sperm-egg interaction is crucial for fertilization, and the tetraspanin protein CD81 plays a vital role in this process for mammals.
- In bovine oocytes, CD81 is present at different maturation stages and accumulates in the perivitelline space during fertilization, showing its importance in sperm-egg fusion.
- Comparisons between bovine and mouse sperm reveal similarities in CD81 localization, but also highlight species-specific differences, particularly during the acrosome reaction that may affect fertilization mechanisms.
The objective of this research was to study the expression of cell membrane molecules CD9 and CD41/61 of transgenic rabbit with integrated human factor VIII (rhFVIII) gene construct. The expressions of these molecules have been monitored during two lactations of transgenic rabbits and simultaneously compared with the expression of the same molecules of non-transgenic rabbits. The immunochemical analysis by indirect immunofluorescence, ELISA and indirect immunoperoxidase staining of blood cells and udder tissues show that the insertion of the WAP-hFVIII gene construct into the rabbit genome, do not influence the expression of cell membrane antigens CD9 and CD41/61 on the blood platelets, polymorphonuclear blood cells, milk somatic cells and mammary gland tissues.
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- CD46 is a complement regulatory protein important for reproduction, found on the inner acrosomal membrane of sperm from humans and some animals.
- Unlike other complement proteins, CD46 is not present on the plasma membrane of human sperm despite potential activating agents in the follicular fluid.
- Research using dual immunofluorescence suggests that in bovine sperm, CD46 may be located on the outer acrosomal membrane and possibly the plasma membrane, rather than the inner acrosomal membrane.