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Micronuclei and their connection with intracellular innate immunity and viral infection
Knoblochová, Kateřina ; Bruštíková, Kateřina (advisor) ; Španielová, Hana (referee)
Micronuclei are tiny structures that contain nuclear DNA and a membrane derived from the nucleus. They emerge in cells that have been exposed to severe stress factors, such as viral infections, radiation, or genotoxic substances. While micronuclei have long been used as markers of genotoxic stress, the mechanism of their formation and internal processes are not yet fully understood. DNA enclosed inside micronuclei is restructured in an atypical manner, which may induce mutations and accelerate oncogenic transformation of the cell. Due to these processes micronuclei can also act as reservoirs of immunostimulatory nucleic acids, which may potentially be detected by molecular sensors. Therefore, studying micronuclei is significant in relation to the activation of signaling pathways that are part of the innate intracellular immunity. This work summarizes the current knowledge about micronuclei and their connection to innate intracellular immunity and viral infection. Keywords: micronuclei, innate immunity, molecular sensors, chromotripsis
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Polyomavirus minichromosomes: interactions with components of innate imunity
Satratzemis, Christos ; Forstová, Jitka (advisor) ; Trejbalová, Kateřina (referee)
The genome of polyomaviruses is a circular dsDNA (double-stranded DNA) which is associated with cellular histones within virions and during the entire viral replication cycle. Given the structural similarity to eukaryotic chromatin, the complex of polyomaviral DNA with histones is called minichromosome. The chromatin state of minichromosomes influences viral transcription and replication which could be exploited by the host innate immune response. One of the components of innate immunity, that affects viral chromatin, is the non-canonical histone H3.3, its chaperone DAXX- ATRX (death domain associated protein 6-alpha-thalassemia, mental retardation X-linked syndrome) and protein complexes called PML (promyelocytic leukemia protein). In order to trigger the innate immune response, foreign and/or stress molecules have to detected. During mouse polyomavirus (MPyV) infection, the innate immune response is initiated via the DNA sensor cGAS (cyclic GMP- AMP synthase). In this master's thesis, the distribution of histone H3.3, its chaperone DAXX-ATRX and the PML protein was analyzed during infection with MPyV. Using mass spectrometry, the histone was detected within viral chromatin. The data suggest that the chaperone complex and PML are involved in the regulation of H3.3 incorporation into the chromatin...
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Host-microbiota, pro-inflammatory immunity and physiological senescence in wild birds
Těšický, Martin
Triggered by microbial ligands, inflammation serves as a "double-edged sword" to fight infections on the one hand, but on the other hand causing tissue damage due to oxidative stress if it is dysregulated. For example, chronic inflammation can contribute to inflammaging, which is now widely regarded as one of the causes of ageing. In my interdisciplinary dissertation, my colleagues and I investigated three interrelated aspects of inflammation, using an evolutionary framework and various free-living birds as models: (1) ecological and evolutionary determinants of gut microbiota (GM) composition and diversity, a driver of wild bird immunity, (2) diversity in immune genes affecting inflammatory responses in wild birds and (3) inflammation-related physiological senescence in a free-living passerine bird, the great tit (Parus major). Firstly, using 16S rRNA gene metabarcoding, we revealed high intra- and interspecific variation in passerine gut microbiota (GM) dominated by the major phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Although in mammals GM depends strongly on host phylogeny and diet, in birds we found only moderate effects of phylogeny and very limited effects of host geography and ecology on GM composition. While microbiota diverged between the upper and lower...
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Host-microbiota, pro-inflammatory immunity and physiological senescence in wild birds
Těšický, Martin ; Vinkler, Michal (advisor) ; Tschirren, Barbara (referee) ; Štěpánek, Ondřej (referee)
Triggered by microbial ligands, inflammation serves as a "double-edged sword" to fight infections on the one hand, but on the other hand causing tissue damage due to oxidative stress if it is dysregulated. For example, chronic inflammation can contribute to inflammaging, which is now widely regarded as one of the causes of ageing. In my interdisciplinary dissertation, my colleagues and I investigated three interrelated aspects of inflammation, using an evolutionary framework and various free-living birds as models: (1) ecological and evolutionary determinants of gut microbiota (GM) composition and diversity, a driver of wild bird immunity, (2) diversity in immune genes affecting inflammatory responses in wild birds and (3) inflammation-related physiological senescence in a free-living passerine bird, the great tit (Parus major). Firstly, using 16S rRNA gene metabarcoding, we revealed high intra- and interspecific variation in passerine gut microbiota (GM) dominated by the major phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Although in mammals GM depends strongly on host phylogeny and diet, in birds we found only moderate effects of phylogeny and very limited effects of host geography and ecology on GM composition. While microbiota diverged between the upper and lower...
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Mechanisms used by SARS-CoV-2 for escape from innate host defense
Rybová, Lucie ; Němečková, Šárka (advisor) ; Pospíšek, Martin (referee)
SARS-CoV-2 of the Coronaviridae family causes the disease called Covid-19. It has a number of structural, non-structural and accessory proteins that interfere with the host's immune response and help the virus escape this response and survive in the host. The most important escape mechanism is suppression of host interferon function. Molecules causing inhibition of the host's innate immunity are encoded from the region of the virus genome ORF1a and ORF1ab. This work provides a summary of the characterization, morphology, genome, replication cycle, innate immunity mechanisms involved in host defense against infection, and escape mechanisms of SARS-CoV-2. Keywords: SARS-CoV-2, virus, morfology of SARS-CoV-2, SARS-CoV-2 genome, structural proteins, nonstructural proteins, innate immune system escape, IFN dysregulation, TLRs, SARS-CoV-2 variants, Covid-19
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Cellular factors restricting mouse polyomavirus infection in host cells: Studies of PML protein isoforms
Anderová, Karolína ; Forstová, Jitka (advisor) ; Němečková, Šárka (referee)
Promyelocytic leukaemia nuclear bodies (PML NBs) are multifunctional nuclear spherical structures formed by the PML protein shell and other interaction partners that have been described to be involved in many cellular processes and immune defences. In the antiviral immune response, PML NBs and their components act as direct restriction factors as well as in the regulation of the interferon response. On the other hand, viruses have developed antagonistic mechanisms to resist this inhibition. This work deals with the role of PML NBs in infection with model Murine polyomavirus (MPyV) and focuses on the study of PML protein isoforms. The first aim of the work was to analyse the formation of human (hPML) and mouse (mPML) NBs in a mouse embryonic fibroblast (MEF) model. Subsequently, the localization of hPML and mPML NBs during infection was determined. Close localization with viral replication centres was observed for both PML species. In the next step, the effect of infection or interferon α (IFNα) on mPML protein expression was tested. Infection and treatment with IFNα led to an increase in mPML expression at the level of both gene transcription and protein synthesis. At the same time, the data indicated the largest increase in transcription of the mPML3 isoform. The work also addressed the potential...
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Role of peripheral blood monocytes and innate immunity in diabetes
Zinková, Alžběta ; Daňková, Pavlína (advisor) ; Novota, Peter (referee)
Introduction: Diabetes mellitus is a polygenic disease and its development is influenced to some extent by environmental factors as well. Innate immunity triggers nonspecifically first defense reactions after penetration of the pathogen into the body, while overstimulation components of innate immunity may give rise to autoimmune diseases, including diabetes type 1. The components of innate immunity are, among others, Toll-like receptors (TLRs) belonging to a group of the structures recognizing preserved molecular structures characteristic of pathogens. Toll-like receptors are abundantly expressed by monocytes which produce prolactin (PRL) having an immunostimulatory function. To clarify the role of innate immunity in the pathogenesis of diabetes, we focused on the expression of mRNA and protein expression of TLR2 and TLR4. The expression of PRL was studied only at the level of mRNA. Monocytes were separated by flow cytometry into classical (CD14++) and nonclassical (CD14+). We monitored their percentages and the degree of expression of CD14 antigen on their surface.The operational objective of this dissertation was to optimize the stimulation of monocytes for the planned study of the function of non-pituitary prolactin in vitro and determine the appropriateness of the use of healthy donors' buffy...
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Molekulárna charakterizácia vybraných obranných faktorov v čeľadi Lumbricidae
Mančíková, Veronika ; Bilej, Martin (advisor) ; Král, Jiří (referee)
Earthworms belonging to oligochaete annelids have been a model for comparative immunology for over 40 years. They possess various defense mechanisms efficiently recognizing and responding to non-self substances. Among these there are molecules with many biological activities including cytolytic, antimicrobial and proteolytic. This work is aimed to compare the immunological features of two closely related earthworm species Eisenia andrei and Eisenia fetida. Due to many morphological and life cycle similarities they have been, until recently, regarded as members of subspecies. Interestingly, their natural habitat varies considerably, and it was of particular interest to investigate how these environmental differences affect the features of innate immunity of both species. Key words: annelids, innate immunity, Eisenia andrei, Eisenia fetida, CCF, fetidin, lysenin, lysozyme
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Induction of innate immune response against intracellular bacterium Francisella tularensis
Sommerová, Gabriela ; Konečná, Klára (advisor) ; Myslivcová Fučíková, Alena (referee)
Background: The purpose of this bachelor thesis is to describe Francisella tularensis and activation of innate immunity during host infection. Main findings: The main findings of the work include the method of recognition of F. tularensis via Toll-like receptors, the production of cytokines and chemokines and the subsequent involvement of other components of innate immunity, including neutrophils, NK cells, or humoral components of the immune response, which also includes complement. The information is based on a number of studies performed mainly on mouse models. Conclusions: The intracelullar bacterium F. tularensis is known to cause tularemia. Its high infectivity, together with the high risk of death in the lung form, raises great concerns about the misuse of this bacterium as a biological weapon. To date, not all of its mechanisms of pathogenesis are known, which is a major problem in the development of effective vaccines. The induction of innate immunity appears to be very important in the host's defense against F. tularensis. However, despite several decades of research, the mechanisms of F. tularensis involved in host cell manipulation, including the regulation of the induction of immune response to F. tularensis infection, have still not been fully elucidated. Key words: Francisella...
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