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Ezrin-Radixin-Moesin (ERM) proteins: The link between tetraspanin web and cytoskeleton in gametes
Picková, Jana ; Frolíková, Michaela (advisor) ; Lánská, Eva (referee)
Ezrin, which belongs to the ERM protein family along with radixin and moesin, plays an important role in linking membrane proteins to the actin cytoskeleton. In sperm, ezrin was described so far in bovine and humans, where it probably contributes in actin polymerization during capacitation. During the acrosome reaction, actin plays a significant role in relocation of protein from the inner acrosomal membrane to the equatorial segment, which is an essential process for successful fertilization. One of the proteins that relocates to the equatorial segment, the site of initiation of gamete fusion, is protein CD9. This protein probably stabilizes protein interactions between sperm and oocyte during gamete fusion. In this diploma thesis, we focused on the role of ezrin in linking the CD9 protein to the actin cytoskeleton in mouse sperm. Using indirect immunofluorescence, we detected ezrin, CD9 and actin in acrosome intact mouse sperm. The co-localization of these proteins in the apical acrosomal region suggests their interactions. However, this was not confirmed by our co-immunoprecipitation experiments. Nevertheless, in the apical acrosomal region we also detected EWI-2 protein, which could act as linker between CD9 and ezrin. In this thesis, we also investigated changes in levels of active...
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Monitoring of protein network dynamics: the role of FcRL proteins during sperm-egg membrane interaction
Bašus, Kryštof ; Komrsková, Kateřina (advisor) ; Šušor, Andrej (referee)
Sperm--egg membrane interaction and fusion is mediated by various molecules of the different protein network that are located on both egg and sperm membrane. So far, many proteins have been selected to be fusion candidates, some of them (Izumo1, CD9, Juno) were proven to be essential, whereas others were discovered to play an unsuspected new active role (CD46, tetraspanins). After the adhesion of sperm to an egg, Juno located on the oolema associates with monomeric Izumo1 on sperm membrane, which is results in Izumo1 dimerization following quick removal of Juno from the egg surface as described in mouse. It implies that additional receptor on the egg membrane is required to play a role in sperm--egg fusion. To find a human fusogenic receptor for IZUMO1 protein we used one--bead--one--compound (OBOC) assay, a random screening approach. A bead, fulfilling all the requirements when interacting with the human sperm, carried a peptide sequence showing homology with the conserved Ig domain of the human specific Fc receptor--like protein 3 (FcRL3). In general, the ...
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Monitoring of protein network dynamics: the role of FcRL proteins during sperm-egg membrane interaction
Bašus, Kryštof ; Komrsková, Kateřina (advisor) ; Šušor, Andrej (referee)
Sperm--egg membrane interaction and fusion is mediated by various molecules of the different protein network that are located on both egg and sperm membrane. So far, many proteins have been selected to be fusion candidates, some of them (Izumo1, CD9, Juno) were proven to be essential, whereas others were discovered to play an unsuspected new active role (CD46, tetraspanins). After the adhesion of sperm to an egg, Juno located on the oolema associates with monomeric Izumo1 on sperm membrane, which is results in Izumo1 dimerization following quick removal of Juno from the egg surface as described in mouse. It implies that additional receptor on the egg membrane is required to play a role in sperm--egg fusion. To find a human fusogenic receptor for IZUMO1 protein we used one--bead--one--compound (OBOC) assay, a random screening approach. A bead, fulfilling all the requirements when interacting with the human sperm, carried a peptide sequence showing homology with the conserved Ig domain of the human specific Fc receptor--like protein 3 (FcRL3). In general, the ...
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