In mammals, integrins are heterodimeric transmembrane glycoproteins that represent a large group of cell adhesion receptors involved in cell-cell, cell-extracellular matrix, and cell-pathogen interactions. Integrin receptors are an important part of signalization pathways and have an ability to transmit signals into and out of cells and participate in cell activation. In addition to somatic cells, integrins have also been detected on germ cells and are known to play a crucial role in complex gamete-specific physiological events, resulting in sperm-oocyte fusion. The main aim of this review is to summarize the current knowledge on integrins in reproduction and deliver novel perspectives and graphical interpretations presenting integrin subunits localization and their dynamic relocation during sperm maturation in comparison to the oocyte. A significant part of this review is devoted to discussing the existing view of the role of integrins during sperm migration through the female reproductive tract; oviductal reservoir formation; sperm maturation processes ensuing capacitation and the acrosome reaction, and their direct and indirect involvement in gamete membrane adhesion and fusion leading to fertilization.

• Klíčová slova
• fusion, integrins, oocyte, reproduction, sperm, sperm activation,
• MeSH
• integriny metabolismus   MeSH
• interakce spermie a vajíčka fyziologie   MeSH
• kapacitace spermií * MeSH
• lidé MeSH
• oocyty cytologie   metabolismus   MeSH
• spermie cytologie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• integriny MeSH

Integrins are transmembrane receptors that facilitate cell adhesion and cell-extracellular matrix communication. They are involved in the sperm maturation including capacitation and gamete interaction, resulting in successful fertilization. αV integrin belongs to the integrin glycoprotein superfamily, and it is indispensable for physiological spermiogenesis and testosterone production. We targeted the gene and protein expression of the αV integrin subunit and described its membrane localization in sperm. Firstly, in mouse, we traced αV integrin gene expression during spermatogenesis in testicular fraction separated by elutriation, and we detected gene activity in spermatogonia, spermatocytes, and round spermatids. Secondly, we specified αV integrin membrane localization in acrosome-intact and acrosome-reacted sperm and compared its pattern between mouse, pig, and human. Using immunodetection and structured illumination microscopy (SIM), the αV integrin localization was confined to the plasma membrane covering the acrosomal cap area and also to the inner acrosomal membrane of acrosome-intact sperm of all selected species. During the acrosome reaction, which was induced on capacitated sperm, the αV integrin relocated and was detected over the whole sperm head. Knowledge of the integrin pattern in mature sperm prepares the ground for further investigation into the pathologies and related fertility issues in human medicine and veterinary science.

• Klíčová slova
• human, male germ cells, mouse, pig, sperm, αV integrin,
• MeSH
• akrozomální reakce MeSH
• integrin alfaV metabolismus   MeSH
• lidé MeSH
• myši MeSH
• prasata MeSH
• spermie metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• integrin alfaV MeSH

It is known that tetraspanin proteins are involved in many physiological somatic cell mechanisms. Additionally, research has indicated they also have a role in various infectious diseases and cancers. This review focuses on the molecular interactions underlying the tetraspanin web formation in gametes. Primarily, tetraspanins act in the reproductive tract as organizers of membrane complexes, which include the proteins involved in the contact and association of sperm and oocyte membranes. In addition, recent data shows that tetraspanins are likely to be involved in these processes in a complex way. In mammalian fertilization, an important role is attributed to CD molecules belonging to the tetraspanin superfamily, particularly CD9, CD81, CD151, and also CD63; mostly as part of extracellular vesicles, the significance of which and their potential in reproduction is being intensively investigated. In this article, we reviewed the existing knowledge regarding the expression of tetraspanins CD9, CD81, CD151, and CD63 in mammalian spermatozoa, oocytes, and embryos and their involvement in reproductive processes, including pathological events.

• Klíčová slova
• CD151, CD63, CD81, CD9, Extracellular vesicles,
• MeSH
• embryonální vývoj MeSH
• lidé MeSH
• oocyty fyziologie   MeSH
• rozmnožování * MeSH
• savci fyziologie   MeSH
• spermie fyziologie   MeSH
• tetraspaniny fyziologie   MeSH
• zvířata MeSH
• zygota fyziologie   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• tetraspaniny MeSH

The physiological importance of CD151 tetraspanin is known from somatic cells and its outside-in signalling through integrins was described. In male germ cells, two tetraspanins, CD9 and CD81, are involved in sperm-egg membrane fusion, and similarly to integrins, they occupy characteristic regions. We report here on a newly discovered presence of CD151 in sperm, and present its expression and distribution during spermatogenesis and sperm transition during the acrosome reaction. We traced CD151 gene and protein expression in testicular cell subpopulations, with strong enrichment in spermatogonia and spermatids. The testicular and epididymal localization pattern is designated to the sperm head primary fusion site called the equatorial segment and when compared to the acrosome vesicle status, CD151 was located into the inner acrosomal membrane overlying the nucleus. Moreover, we show CD151 interaction with α6 integrin subunit, which forms a dimer with β4 as a part of cis-protein interactions within sperm prior to gamete fusion. We used mammalian species with distinct sperm morphology and sperm maturation such as mouse and bull and compared the results with human. In conclusion, the delivered findings characterise CD151 as a novel sperm tetraspanin network member and provide knowledge on its physiology in male germ cells.

• MeSH
• antigeny CD151 chemie   genetika   metabolismus   MeSH
• exprese genu * MeSH
• fluorescenční protilátková technika MeSH
• integrin alfa6 chemie   metabolismus   MeSH
• konformace proteinů MeSH
• lidé MeSH
• molekulární modely MeSH
• myši MeSH
• spermie metabolismus   MeSH
• testis metabolismus   MeSH
• transport proteinů MeSH
• vazba proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zárodečné buňky metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigeny CD151 MeSH
• integrin alfa6 MeSH

Currently, considering cryopreservation of bull semen, there is no clear consensus over the comparability of cryoprotective efficacy of extenders with soybean lecithin and those based on egg yolk. The objective of this study was to prove the use of Low Density Lipoprotein (LDL) extracted from hen-egg yolk as an enhancing factor for soybean lecithin-based extenders. In total, 35 ejaculates of (seven bulls x five ejaculates per bull) were collected and cryopreserved at a commercial insemination centre. The effect of the LDL addition to the extenders AndroMed® and Bioxcell® was tested in a 6% (v/v) concentration on spermatozoa after thawing. Modified extender composition effects were assessed on sperm functional parameters motility, plasma membrane, mitochondrial membrane potential and acrosomal integrity after thawing by CASA, flow cytometry and fluorescent microscopy, respectively. Based on kinematic parameters determined from CASA, k-means cluster analysis was used to classify individual spermatozoon into specific subpopulations (fast, medium fast and slow). A subpopulation of fast spermatozoa was increased in the presence of LDL in both selected extenders (P < 0.05). Moreover, the positive effect of LDL on sperm motility was confirmed by decreasing the percentage of sperm in slow subpopulation (P < 0.05). The effect of LDL addition on the incidence of spermatozoa with intact plasma membrane was not demonstrated in any case of extender used (P > 0.05). The percentage of sperm with intact acrosome was improved when LDL was added to Bioxcell® extender (P < 0.05). On the other hand, addition of LDL to AndroMed® extender improved mitochondrial intactness after thawing (P < 0.05). In conclusion, our results showed that adding LDL to selected soybean lecithin-based extenders considerably ameliorated the functional parameters of spermatozoa after thawing and thus this lipoprotein could represent an improving agent for soybean lecithin-based extender for bull semen cryopreservation.

• Klíčová slova
• Low Density Lipoprotein, cryopreservation, spermatozoa,
• Publikační typ
• časopisecké články MeSH

Proteins CD9 and CD81 are members of the tetraspanin superfamily and were detected in mammalian sperm, where they are suspected to form an active tetraspanin web and to participate in sperm⁻egg membrane fusion. The importance of these two proteins during the early stages of fertilization is supported by the complete sterility of CD9/CD81 double null female mice. In this study, the putative mechanism of CD9/CD81 involvement in tetraspanin web formation in sperm and its activity prior to fertilization was addressed. Confocal microscopy and colocalization assay was used to determine a mutual CD9/CD81 localization visualised in detail by super-resolution microscopy, and their interaction was address by co-immunoprecipitation. The species-specific traits in CD9 and CD81 distribution during sperm maturation were compared between mice and humans. A mutual position of CD9/CD81 is shown in human spermatozoa in the acrosomal cap, however in mice, CD9 and CD81 occupy a distinct area. During the acrosome reaction in human sperm, only CD9 is relocated, compared to the relocation of both proteins in mice. The structural modelling of CD9 and CD81 homologous and possibly heterologous network formation was used to propose their lateral Cis as well as Trans interactions within the sperm membrane and during sperm⁻egg membrane fusion.

• Klíčová slova
• CD81, CD9, acrosome reaction, capacitation, fertilization, human, membrane fusion, mouse, sperm, structural modelling, tetraspanin network,
• MeSH
• akrozomální reakce * MeSH
• antigeny CD81 analýza   metabolismus   MeSH
• antigeny CD9 analýza   metabolismus   MeSH
• fertilizace MeSH
• fúze membrán MeSH
• kapacitace spermií * MeSH
• lidé MeSH
• mapy interakcí proteinů MeSH
• molekulární modely MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• spermie cytologie   metabolismus   ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antigeny CD81 MeSH
• antigeny CD9 MeSH