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

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

The mechanism of gamete fusion remains largely unknown on a molecular level despite its indisputable significance. Only a few of the molecules required for membrane interaction are known, among them IZUMO1, which is present on sperm, tetraspanin CD9, which is present on the egg, and the newly found oolema protein named Juno. A concept of a large multiprotein complex on both membranes forming fusion machinery has recently emerged. The Juno and IZUMO1, up to present, is the only known extracellular receptor pair in the process of fertilization, thus, facilitating the essential binding of gametes. However, neither IZUMO1 nor Juno appears to be the fusogenic protein. At the same time, the tetraspanin is expected to play a role in organizing the egg membrane order and to interact laterally with other factors. This review summarizes, to present, the known molecules involved in the process of sperm-egg fusion. The complexity and expected redundancy of the involved factors makes the process an intricate and still poorly understood mechanism, which is difficult to comprehend in its full distinction.

• MeSH
• fertilizace fyziologie   MeSH
• imunoglobuliny metabolismus   MeSH
• integriny metabolismus   MeSH
• lidé MeSH
• membránové proteiny metabolismus   MeSH
• ovum metabolismus   MeSH
• proteiny semenné plazmy metabolismus   MeSH
• receptory buněčného povrchu metabolismus   MeSH
• spermie metabolismus   MeSH
• tetraspaniny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• imunoglobuliny MeSH
• integriny MeSH
• IZUMO1 protein, human MeSH Prohlížeč
• membránové proteiny MeSH
• proteiny semenné plazmy MeSH
• receptory buněčného povrchu MeSH
• tetraspaniny MeSH