Involvement of protein vinculin in mammalian gametogenesis

One of the basic characteristics of living systems is a sexual reproduction, when the germ cells, sperm and egg, fuse. The key process in the germ cells development is meiosis. During meiotic division, several dramatic changes happen in the nucleus and different errors might appear, which may then result in various chromosomal aberrations and nondisjunctions leading to genetic diseases and infertility. The causes of infertility are very diverse, but many of them obviously come from the meiotic errors. One of the most critical parts for the successful meiotic progress is a prophase I, where the homologous chromosomes are paired by the protein structure of the synaptonemal complex (SC) and subsequent genetic recombinations by crossing- over accurate. Vinculin (VCL) is a cytoplasmic actin binding protein in the focal adhesions and adherent junctions and VCL acts as their essential regulator. Recently, this protein was also found in the nucleus of germ cells of certain organisms. However, the nuclear functions of vinculin have not been described yet. This diploma thesis focuses on the study of chromosomal dynamics in the gametogenesis of our mouse model, regarding the involvement of the nuclear vinculin in these processes. Our aim was to localize VCL in the nucleus of embryonic prophase oocytes using...Jednou ze základních vlastností živých soustav je pohlavní rozmnožování, při kterém dochází ke splynutí pohlavních buněk, spermie a vajíčka. Klíčovým procesem, při tvorbě pohlavních buněk, je meióza. Při meiotickém dělení dochází k dramatickým změnám v jádře, při kterých se mohou vyskytnout chyby, které mohou zapříčinit různé chromozomové aberace a nondisjunkce vedoucí ke genetickým onemocněním a v neposlední řadě k neplodnosti. Příčiny neplodnosti jsou velmi různorodé, avšak velká část pochází právě z chyb při meióze. Pro správné fungování tohoto procesu je velmi důležitá první fáze meiózy I, profáze I, kde dochází k párování homologních chromozomů za pomoci bílkovinné struktury synaptonemálního komplexu (SC) a následně dochází ke genetické rekombinaci, tzv. crossing-overu. Vinkulin (VCL) je cytoplazmatický protein vázající aktin ve fokálních adhezích a adherentních spojích a je jejich esenciálním regulátorem. Tento protein byl však objeven i v jádře pohlavních buněk u některých organizmů. Jaderné funkce vinkulinu však dosud nebyly popsány. Tato diplomová práce se zaměřuje na studium dynamiky chromozomů v gametogenezi na myším modelu s důrazem na zapojení jaderného vinkulinu (VCL) do těchto procesů. Naším cílem bylo lokalizovat VCL v jádře embryonálních profázních oocytů pomocí fluorescenční...Katedra antropologie a genetiky člověkaDepartment of Anthropology and Human GeneticsPřírodovědecká fakultaFaculty of Scienc

Involvement of protein vinculin in mammalian gametogenesis

One of the basic characteristics of living systems is a sexual reproduction, when the germ cells, sperm and egg, fuse. The key process in the germ cells development is meiosis. During meiotic division, several dramatic changes happen in the nucleus and different errors might appear, which may then result in various chromosomal aberrations and nondisjunctions leading to genetic diseases and infertility. The causes of infertility are very diverse, but many of them obviously come from the meiotic errors. One of the most critical parts for the successful meiotic progress is a prophase I, where the homologous chromosomes are paired by the protein structure of the synaptonemal complex (SC) and subsequent genetic recombinations by crossing- over accurate. Vinculin (VCL) is a cytoplasmic actin binding protein in the focal adhesions and adherent junctions and VCL acts as their essential regulator. Recently, this protein was also found in the nucleus of germ cells of certain organisms. However, the nuclear functions of vinculin have not been described yet. This diploma thesis focuses on the study of chromosomal dynamics in the gametogenesis of our mouse model, regarding the involvement of the nuclear vinculin in these processes. Our aim was to localize VCL in the nucleus of embryonic prophase oocytes using..

Structural aberrations of human chromosome 22 and their clinical consequences

Structural aberrations are due to chromosome breaks followed by specific reconstruction. Every day in human genome thousands of small mutations occur, which are due to reparation processes repaired restored to its original form. As a result of bad repairs there may occur deletions, duplications, translocations and other changes that often cause various human diseases and syndromes. These mutations arise spontaneously or by external factors or by combination of both. Chromosome 22, the second smallest chromosome in the human genome, is a subject to these mutations very easily due to its large recombinant sequences called LCRs, which together share about 98% homology. Although the chromosome 22 ranks among the small acrocentric chromosomes, it contains a lot of important structural genes and in these regions may lead to serious diseases. The best known disease caused by deletions in the region 22q11 is DiGeorge/Velocardofacial syndrome which occurs with a frequency of 1:4000. Uncommon, but equally serious disease, the Cat eye syndrome, formed by aberrations in band 22q11.2 and characterized by coloboma of the iris, anal atresia and heart defects or mental retardation. Reciprocal translocations on chromosome 22 may lead for example to Emanuel syndrome, which is characterized supernumerary derivatized..

Focal Adhesion Protein Vinculin Is Required for Proper Meiotic Progression during Mouse Spermatogenesis

The focal adhesion protein Vinculin (VCL) is ascribed to various cytoplasmic functions; however, its nuclear role has so far been ambiguous. We observed that VCL localizes to the nuclei of mouse primary spermatocytes undergoing first meiotic division. Specifically, VCL localizes along the meiosis-specific structure synaptonemal complex (SC) during prophase I and the centromeric regions, where it remains until metaphase I. To study the role of VCL in meiotic division, we prepared a conditional knock-out mouse (VCLcKO). We found that the VCLcKO male mice were semi-fertile, with a decreased number of offspring compared to wild-type animals. This study of events in late prophase I indicated premature splitting of homologous chromosomes, accompanied by an untimely loss of SCP1. This caused erroneous kinetochore formation, followed by failure of the meiotic spindle assembly and metaphase I arrest. To assess the mechanism of VCL involvement in meiosis, we searched for its possible interacting partners. A mass spectrometry approach identified several putative interactors which belong to the ubiquitin–proteasome pathway (UPS). The depletion of VLC leads to the dysregulation of a key subunit of the proteasome complex in the meiotic nuclei and an altered nuclear SUMOylation level. Taken together, we show for the first time the presence of VCL in the nucleus of spermatocytes and its involvement in proper meiotic progress. It also suggests the direction for future studies regarding the role of VCL in spermatogenesis through regulation of UPS