National Repository of Grey Literature 27 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Involvement of protein vinculin in mammalian gametogenesis
Darášová, Alžběta ; Hozák, Pavel (advisor) ; Kaňka, Jiří (referee)
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...
Function of nuclear phosphoinositides and their binding partners in gene expression
Uličná, Lívia ; Hozák, Pavel (advisor) ; Šolc, Petr (referee) ; Macůrková, Marie (referee)
(ENGLISH) Phosphoinositides (PIs) are negatively charged glycerol-based phospholipids with inositol head (ring) which can be phosphorylated. Inositol ring phosphorylation yields in seven different PIs species which can be mono-, bis,- or tris-phosphorylated. Roles of cytoplasmic PIs have been extensively studied in for membrane and cytoskeletal dynamics, vesicular trafficking, ion channels and transporters and generating of second messengers. Nuclear PIs have been implicated in posttranscriptional processing of pre-mRNA, DNA transcription and chromatin remodelling. While cytoplasmic functions are very well described, the molecular mechanism of their nuclear functions are still poorly understood. In this study we focus on description of localization of nuclear PIs in particular functional nuclear compartments, which enable us to reveal PIs involvement in nuclear processes. We also focused on identification of nuclear PIs involved in the regulation of genes transcription and revealed detailed mechanism of PI(4,5)P2 a PHF8 interaction in the regulation of ribosomal genes transcription. By two independent approaches, we have described PIs localization to the nuclear membrane, nuclear speckles, small foci in the nucleoplasm, and the nucleolus. This spread nuclear localization suggests and confirms PI's...
New Possibilities in Fluorescence Correlation Spectroscopy
Benda, Aleš ; Hof, Martin (advisor) ; Hozák, Pavel (referee) ; Valenta, Jan (referee) ; Vácha, František (referee)
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Manipulating the mammalian oocyte and embryo - Biological and epigenetic aspects
Fulková, Helena ; Hozák, Pavel (advisor) ; Hampl, Aleš (referee) ; Motlík, Jan (referee)
CONCLUSIONS . By antibodies against ďfferent covalent histone modifications and 5-methylcytosine, we have partialty characterised the epigenetic changes taking place during the oocyte mauration and in early mammalian embryogenesis in the mouse and pig, respectively. o We have also characterised thc epigenetic repogramming activities of cytoplasts derived from oocytes at different stages of maturation after somatic cell nuclear transfer. . We have evaluated the epigenetic effec$ of selected procedures that are currently used for embryo production. . Finally, we have developed a new cryopreservation scheme for oocyte nuclear material storage. orrr research is engaged in the development ofnew bíotechniques as well as elucidating and characterising the epigenetic pÍocesses that take place during normal and abnormal embryogenesis. Abnormal embryonic development is for example often observed in somatic cell nuclear transfer embryos. These techniques can also be potentially used not only in human medicine but also for valuable livestock and endangered species preservation Oy e.g. interspecies nuclear transfer). Especially in human meďcine, attention to the ethical issues associated with these techniques must be paid. It is also clear tbat many biological problems still do exist and these should not be...
Localization and function of phosphoinositides in the cell nucleus
Kalasová, Ilona ; Hozák, Pavel (advisor) ; Stopka, Tomáš (referee) ; Šolc, Petr (referee)
(ENGLISH) Phosphoinositides (PIs) are negatively charged glycerol-based phospholipids. Their inositol head can be phosphorylated at three positions generating seven differently phosphorylated species. Cytoplasmic phosphoinositides regulate membrane and cytoskeletal dynamics, vesicular trafficking, ion channels and transporters and generate second messengers. In the nucleus, PIs are implicated in pre-mRNA processing, DNA transcription and chromatin remodelling. However, their nuclear functions are still poorly understood. Here we focus on nuclear phosphatidylinositol 4-phosphate (PI(4)P) and phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2). We describe their localization and interaction with proteins involved in regulation of DNA transcription. PI(4)P localizes to nuclear membrane, nuclear speckles and nucleoplasm. The majority of nuclear PI(4)P is associated with chromatin and colocalizes with H3K4me2. PI(4,5)P2 localizes to nucleoli and nuclear speckles. Besides, 30 % of nuclear PI(4,5)P2 forms small nucleoplasmic PI(4,5)P2 islets. They have carbon rich core, which is probably formed by lipids, and are surrounded by proteins and nucleic acids. The active form of RNA polymerase II associates with PI(4,5)P2 islets and DNA is actively transcribed in the vicinity of PI(4,5)P2 islets. Moreover,...
Mouse polyomavirus: The role of cell cytoskeleton in virus endosomal trafficking and properties of the minor capsid proteins
Žíla, Vojtěch ; Forstová, Jitka (advisor) ; Hozák, Pavel (referee) ; Rumlová, Michaela (referee)
Mouse polyomavirus (MPyV) is a non-enveloped DNA tumor virus, which replicates in the host cell nucleus. MPyV enters cells by receptor-mediated endocytosis and its subsequent transport towards the nucleus requires acidic environment of endosomes and intact microtubules, which are important for virus delivery to endoplasmic reticulum (ER). In ER, capsid disassembly and uncoating of viral genome take place. The mechanism of subsequent translocation of viral genome from ER into nucleoplasm is still only poorly understood process with predicted involvement of cellular factors and viral minor capsid proteins VP2 and VP3. Once the genome appears in the nucleus, early viral antigens are produced and mediate suitable environment for replication of viral genomes. After replication of viral DNA and morphogenesis of virions, virus progeny is released from the cells during its lysis. The research presented in the first part of thesis focused on intracellular transport of MPyV and involvement of cytoskeletal networks during virus delivery to the ER. In particular, we investigated still unclear role of microtubules during virus trafficking in endosomes, and involvement of microtubular motors. We found that MPyV trafficking leading to productive infection does not require the function of kinesin-1 and kinesin-2,...
Development of ultrastructural methods and their application in studies on the cell nucleus
Filimonenko, Anatoly ; Hozák, Pavel (advisor) ; Nebesářová, Jana (referee) ; Lanctôt, Christian (referee)
Despite the capabilities of molecular-biological methods in deciphering the interplay of different biological molecules and molecular complexes, the understanding of respective functions in living cells requires application of in situ methods. Obviously, these methods should provide maximal resolution and the best possible preservation of the biological object in a native state, as well as correct statistical evaluation of the spatial characteristics of detected molecular players. Transmission electron microscopy provides the highest possible resolution for analysis of biological samples. The simultaneous detection of biological molecules by means of indirect immunolabeling provides valuable information about their localization in cellular compartments and their possible interactions in macromolecular complexes. To analyze this, we have developed a complex stereological method for statistical evaluation of immunogold clustering and colocalization patterns of antigens on ultrathin sections, including a user-friendly interface. Functional microarchitecture of DNA replication and transcription sites has been successfully characterized using the developed stereological tools. Our data demonstrate that DNA replication is compartmentalized within cell nuclei at the level of DNA foci and support the view...
Functions of actin and myosin 1c in the cell nucleus and in the cytoplasm
Kalendová, Alžběta ; Hozák, Pavel (advisor) ; Binarová, Pavla (referee) ; Forstová, Jitka (referee)
Human MYO1C gene encodes three myosin 1c (Myo1c) isoforms which differ only at their N-ends. Interestingly, all three isoforms localize to the nucleus and also to the cytoplasm, where they are anchored to the plasma membrane by the interaction with phosphatidyl inositol-4,5-bisphosphate (PIP2). However, studies reporting functional involvement of these isoforms are inconsistent. While the shortest isoform C (Myo1c-isoC) has been implicated exclusively in the cytoplasmic processes, the longer isoform B (termed the nuclear myosin 1, NM1) has been employed in the nuclear and processes, such as DNA transcription and rRNA maturation. Similarly, the longest isoform A (Myo1c-isoA) exerts its functions in the nucleus solely. To complete the information on the cellular functions of Myo1c isoforms, we searched for the cytoplasmic functions of NM1 and nuclear functions of Myo1c-isoC. In mouse, only two isoforms (NM1 and Myo1c-isoC) are expressed. We prepared the knock-out mouse (KO) which lacks specifically NM1 while retaining Myo1c-isoC unchanged. Surprisingly, this manifested in no phenotype observed. Since we demonstrated that even Myo1c-isoC acts in the transcription in the similar manner as NM1, it suggests that Myo1c- isoC functionally overlap with NM1 in the nuclear functions. Besides its localization...
Localization matters: function of paxillin and phopholipids in the cell nucleus
Marášek, Pavel ; Hozák, Pavel (advisor) ; Půta, František (referee) ; Žárský, Viktor (referee)
(English) Both paxillin and PIP2 are well known components of the cell, although of a distinct origin. Focal adhesion protein paxillin spreads the signals from extracellular matrix via integrins and growth factor receptors to affect cellular motility and migration (Schaller, 2001). PIP2, a major structural component of cytoplasmic membrane, is utilized by phospholipase C to generate second messenger molecules (Hokin and Hokin 1953; Streb et al. 1983). Both molecules were recently shown to be localized in the nucleus. Their original functions have been well established, but together with other research colleagues we are now shedding more light on completely different functions of these biological molecules and moreover, in the different compartments than they were primarily believed to function in. Here, we introduce paxillin as an important factor of the cell nucleus, where it regulates transcription of two important growth-related genes, IGF2 and H19. It does not affect the allelic expression of these imprinted genes, it rather regulates long-range chromosomal interactions between H19 or IGF2 promoter, and the shared distal enhacer on an active allele. In detail, paxillin stimulates the interaction between the enhancer and the IGF2 promoter, activating IGF2 gene transcription, while it restrains...

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