|
|
Species-specific structural differences of mammalian sperm and function of their key proteins during fertilization.
Dobrodinská, Anna ; Frolíková, Michaela (advisor) ; Kuntová, Barbora (referee)
The fertilization is a process during which a male and a female gamete merge so that a new organism may come into being. The sperm-egg fusion is preceded by several essential processes, such as the capacitation, acrosome reaction, the sperm binding to the zona pellucida and oolemma, and membrane fusion of the gametes. Numerous proteins, which are located in both sperm and eggs, are major actors in controlling the listed, essential processes. During the process of fertilization these proteins fulfil one or more functions. In mammalian sperm, significant species-specific differences may be found both in their morphology and at the protein level. A complex understanding of species-specific distinctions in sperm structure and functions of key sperm proteins would contribute to a better insight into the process of fertilization, thereby enabling us to better diagnose and subsequently treat the causes of infertility in humans. This bachelor's thesis summarizes the current knowledge of sperm structure and its key proteins that has been acquired through the studies of the following model mammal species: bull, boar, mouse, and human. Further, this thesis brings an interspecific comparison between the studied species. Keywords: sperm, fertilization, acrosome reaction, capacitation, sperm proteins, bull,...
|
|
|
Chemical signals and reproductive processes of the house mouse (Mus musculus)
Černá, Martina
The aim of my thesis was to identify proteins involved in chemical communication and especially those that are involved in sexual signalling. Volatile chemical signals are transported with lipocalins in their beta-barrel structure to present their ligands to receptors or out of the body. Thus, I focused on the identification of these proteins in saliva and vaginal secretion of the house mouse using proteomic and transcriptomic approaches. Due to a cyclic manner of reproduction and its hormonal control, I have also focused on the role of estradiol on sperm phenotype in the laboratory mouse. We have identified an elevated sexual dimorphism in several lipocalins (i.e. 10 out of 20) in the saliva proteome where they may play a role in sexual signalling (i.e. similar to their described roles in the mouse urine). Interestingly, vaginal secretion also contains lipocalins and they rise from proestrus to estrus and remain steady during metestrus. Such variation provides evidence that they serve sexual signalling, however, due to their elevated levels during metestrus it is most likely that their ligands function as signals and not the proteins themselves. On the level of sperm phenotype, we have provided evidence, that experimental concentrations of estradiol have differential effects on sperm. This is due...
|
|
|
Chemical signals and reproductive processes of the house mouse (Mus musculus)
Černá, Martina ; Stopka, Pavel (advisor) ; Petr, Jaroslav (referee) ; Sedláček, Radislav (referee)
The aim of my thesis was to identify proteins involved in chemical communication and especially those that are involved in sexual signalling. Volatile chemical signals are transported with lipocalins in their beta-barrel structure to present their ligands to receptors or out of the body. Thus, I focused on the identification of these proteins in saliva and vaginal secretion of the house mouse using proteomic and transcriptomic approaches. Due to a cyclic manner of reproduction and its hormonal control, I have also focused on the role of estradiol on sperm phenotype in the laboratory mouse. We have identified an elevated sexual dimorphism in several lipocalins (i.e. 10 out of 20) in the saliva proteome where they may play a role in sexual signalling (i.e. similar to their described roles in the mouse urine). Interestingly, vaginal secretion also contains lipocalins and they rise from proestrus to estrus and remain steady during metestrus. Such variation provides evidence that they serve sexual signalling, however, due to their elevated levels during metestrus it is most likely that their ligands function as signals and not the proteins themselves. On the level of sperm phenotype, we have provided evidence, that experimental concentrations of estradiol have differential effects on sperm. This is due...
|
|
|
The influence of estrogens on mouse sperm capacitation and acrosome reaction in vitro
Tejnická, Magda ; Komrsková, Kateřina (advisor) ; Linhart, Otomar (referee)
There are an increasing amount of compounds in the environment that can have a negative effect on reproductive parameters in both male and female organism. There has been a worldwide decline of sperm quality during past decades and this fact lead to an increase of unnatural ways of conception through assisted reproduction techniques in the specialised centres. Natural estrogens are one of these compounds and they get into waste water after being excluded from the body by the urine. They get back into the human body from drinking water or from the food, and they can interfere with function of endogenous hormones in very low concentrations. For these reasons it is up to date to deal with the influence of these compounds on mammalian sperm. For many years, estrogens have been considered typically female sex hormones. It is now certain that they are also very important in the regulation of male reproduction. Endogenous estrogens in mammalian males are an important part of the endocrine system. Estrogens play an important role in the development of germ cells, spermatogenesis and processes leading to successful egg fertilization such as a capacitation or acrosomal reaction. Tyrosine phosphorylation is one of the essential steps for the properly ongoing process of capacitation in sperm followed by a...
|
|
|
Dynamics of acrosome reaction during intra-specific sperm competition in rodents.
Veselá, Kateřina ; Hortová, Kateřina (advisor) ; Pěknicová, Jana (referee)
Dynamics of acrosome reaction during intra-specific sperm competition in rodents Sperm acrosome integrity is disturbed in promiscuous species field mice (Apodemus) and more than half of the spermatozoa undergoing spontaneous acrosome reaction (AR) before binding to the zona pellucida. In Muridae it is documented a generally high rate of spontaneous AR, and the percentage increases in promiscuous species up to 60 % in 60 min capacitation in vitro. The acrosome integrity positively corellates with presence of CD46 protein which absence in wood mouse is fenotypicaly same as in CD46 knock-out mouse leading to accelerated spontaneous AR. It is necessary to clarify whether for mouse sperm it is essential the primary binding of intact sperm to zona pellucida of the egg or whether it is preferred secondary sperm binding after spontaneous AR. In this context, the question is whether there is a relocalization of the key fusion protein IZUMO in sperm during spontaneous AR. IZUMO relocalization was monitored by immunofluorescence at specific times of capacitation in vitro during spontaneous and induced AR. IZUMO relocalization as closely connected to actin cytoskeleton, and β1 integrins. Dynamics and localization of β1 integrin during spontaneous and induced AR was also detected by immunofluorescence. Our results...
|
|
|
Sperm acrosomal reactien in selected species of mammals
Frolíková, Michaela ; Stopka, Pavel (advisor) ; Jonáková, Věra (referee) ; Petr, Jaroslav (referee)
Mammalian sperm must undergo the process of capacitation - series of physiological and biochemical modifications prior fertilization. In last stage of capacitation sperm undergoes acrosome reaction (AR). During AR the cell membrane of the sperm fuses with the outer acrosomal membrane and the contents of acrosomal vesicle are released into extracellular space. Sperm which did not undergo AR or sperm missing acrosome at all are unable to fertilize. AR results into dramatical changes in the sperm head. Most of the proteins present in plasmatic and outer acrosomal membrane are reorganized or lost. There are also significant changes in cytoskeletal and intraacrosomal proteins are released to extracellular space uncovering new surface domains. Some sperms undergo AR even without presence of inductor of AR during capacitation in vitro. This event is called spontaneous (accelerated) AR. The latest research indicates that spontaneous AR is natural part of the process of fertilization. Field mice (Apodemus) show high level of promiscuity leading to significant risk of sperm competition. Unique reproduction strategy where the sperms form so-called sperm trains was evolved in field mice. Spontaneous AR is probably enabling the dissociation of sperms from the sperm train. The spontaneous AR rate is dependent on...
|
|
|
Distribution of CD46 and β1 integrin molecules with respect to different membrane structures of the sperm head
Šebková, Nataša ; Frolíková, Michaela ; Děd, Lukáš ; Dvořáková-Hortová, Kateřina
CD46 protein plays an important role during fertilization and its role is associated with acrosome stability. CD46 is probably involved in signalling pathways triggering the acrosome reaction (AR). It also associates through membrane integrins with specific MAP kinases involved in the AR. Our aim was to monitor the dynamics of relocation of CD46 and β1 integrin during sperm maturation and its preparation for the fertilization. The dependence of this localization changes on the dynamic of actin cytoskeleton was studied. Our results show the changes in the localization of these proteins associated with the AR and their co-localization was observed using proximity ligation assay. After the AR CD46 and β1 integrin spreads across the sperm head, entering the post-acrosomal compartment, and permeates the borders of different domains. It was shown previously that actin dynamics is necessary for acrosome reaction-associated translocation of Izumo1 protein that is required for sperm-egg fusion. Therefore Latrunculin A was used during sperm incubation. The co-incubation of capacitated sperm with Latrunculin A leads to a decrease of the percentages of sperm, which express relocation pattern after induced AR. 3D models and visualizations of potential membrane processes responsible for the relocation of proteins from the acrosomal area to the other compartments of the sperm head were prepared. Our results deliver new information that proteins CD46 and β1 integrin undergo dynamic relocation towards the sites of sperm-egg fusion during the AR in vitro. The inhibitor of actin dynamics abrogates significantly the AR-associated changes in proteins localization. We speculate that this relocation is of importance for the successful sperm-egg interaction, adhesion and subsequent gamete fusion.
|
|
|
CD46 and β1integrin interaction in mouse sperm head
Šebková, Nataša ; Frolíková, Michaela ; Dvořáková-Hortová, Kateřina
CD46 protein plays an important role during fertilization and its role is associated with acrosome stability. CD46 is probably involved in signalling pathways triggering the acrosome reaction. Integrins interact with many cytoskeletal proteins such as actin, therefore changes in the actin cytoskeleton before and after AR may lead to changes in the association and localization of CD46 and β1integrin. Our aim was to monitor mutual CD46 and β1integrin interaction detected by the proximity ligation assay. It generates a localized signal in a form of spots revealing the exact position of the recognition event. Proteins interaction was study in freshly released sperm and sperm during the acrosome reaction, during which there is a gradual relocation of these proteins towards the equatorial segment and the whole sperm head. Proteins α and β tubulin were used as a positive control, α tubulin and β1 integrin as a negative control. In situ PLA showed a distinct spotted signal indicating the mutual interaction of CD46 and β1integrin. A positive response was demonstrated not only in freshly released sperm but also in sperm during the acrosome reaction. Freshly released sperm were distinctively labelled in the acrosome region and the neck, similarly to the positive control. Sperm during the acrosome reaction showed the signal across the whole sperm head region. No signal or sporadic nonspecific staining was detected in the case of the negative control. In summary, our results deliver new information that proteins CD46 and β1 integrin interact with each other. These results suppose the theory that β1 integrin can mediate a connection between CD46 and sperm cytoskeleton thereby molecules of signalling pathways leading to activation of the acrosome reaction.
|
|
|
Dynamics of mouse sperm capacitation and acrosome reaction
Dvořáková-Hortová, Kateřina ; Frolíková, Michaela ; Děd, Lukáš ; Šebková, Nataša
Capacitation followed by the acrosome reaction (AR), is a very complex event of molecular changes, including acrosome matrix rearrangement and actin polymerization, which mammalian sperm must undergo in the female reproductive tract in order to obtain the ability to penetrate and fertilize the egg. CD46 and β1-integrin belong to specific proteins, which are predicted to interact during molecular reorganization of capacitating sperm. The IZUMO1 as the primary fusion protein of the mammalian sperm is also involved in this dynamic network. We investigated the relationship between the Izumo, CD46 and β1 integrin relocation in the sperm head during the capacitation and AR in vitro. We have already successfully monitored by immunofluorescent labelling the dynamics of proteins CD46 and β1-integrin. The changes in the localization of these proteins associated with the AR and their mutual co-localization was observed. The original β1-integrin location in the freshly released epididymal sperm is in the acrosome and it relocates during the AR further through the sperm head compartments into the equatorial segment and over the whole sperm head. Its density over the equatorial segment is decreasing with the extended time of the AR. Also its presence in the perforatorium of the mouse sperm head is very prominent. The pattern for protein CD46 is extremely similar if not identical in both aspects such as compartment localization and time progress during capacitation and AR in vitro. The molecular interaction of CD46 and β1-integrin was investigated using the Proximity Ligation Assay and Super resolution microscopy STED. The data were statistically analysed. The newly obtained results from CD46 and β1-integrin relocation are in correlation with IZUMO1 dynamics and giving a substantial knowledge on the studied protein network rearrangement during capacitation and AR in mouse spermatozoa.
|
|
| |
guest ::
