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Vliv cytosolické nukleotidázy cN-IIIB na imunitní odpověď u \kur{Drosophila melanogaster}
DOLEJŠKOVÁ, Tereza
Adenosine is a key signal molecule of the metabolic switch, a crucial process of metabolic changes in Drosophila melanogaster upon parazitoid wasp infection. However, some components of the adenosine creation pathway have yet to be discovered. We studied a potential convertor of AMP to adenosine in immune response, cN-IIIB, a cytosolic nucleotidase known to accept the methylated RNA cap nucleotide 7-methylguanosine as a substrate and to protect cells against undesired incorporation of this nucleotide into nucleic acids. We suggest this trait can be potentially important in the metabolic switch.
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Různé metodické přístupy za účelem snížení exprese podjednotek komplexu I u hmyzích forem \kur{Trypanosoma brucei}
HEROUTOVÁ, Barbora
Complex I (NADH:ubiquinone dehydrogenase) is the largest protein complex of the mitochondrial electron transport chain, but its presence and activity are not essential for the growth of two life cycle stages of Trypanosoma brucei. Here, we implemented various genetic methods to generate T. brucei cell lines that will lack or will have decreased levels of this complex. The methodological approaches included i) RNA interference of NDUFA6, a subunit predicted to be essential for the structural integrity, and of NUBM, a subunit essential for the complex I activity; ii) generation of double knock-out of NDUFA6 using CRISPR/Cas9; iii) generation of double knock-out of NUBM using homology replacement. These generated tools will help us to elucidate if this highly conserved complex is essential for other life cycle stages of this medically important parasite
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Význam signální dráhy insulinu ve fyziologii klíštěte \kur{Ixodes ricinus}
KOZELKOVÁ, Tereza
In this thesis, the function of the insulin receptor signaling pathway (ISP) in hard ticks Ixodes ricinus was analyzed. Ticks are obligatory blood-feeding (hematophagous) ectoparasites, capable of transmitting a wide variety of pathogens comprising bacteria, viruses, and protozoa that affect animals and humans. The parasite is strictly bonded with its host through a unidirectional transfer of nutrition for its survival, development, and reproduction. The ISP is a highly conserved system, which regulates a variety of physiological and anabolic processes in response to the available nutrition. The aim of the thesis was to examine the function of several key components of this pathway, which had been identified in the midgut transcriptome, namely insulin receptor (IrInR), protein kinase B called AKT (IrAKT), and the target of rapamycin (IrTOR). The subsequent objective was to assess the expression profiles in tick tissues of these components, during tick feeding and after detachment using qRT-PCR. Furthermore, the phenotype using RNAi knockdown, injection with insulin receptor antagonist (IRA), and the artificial feeding with the AKT and TOR inhibitors were verified. Finally, the immunization of rabbits with IrInR recombinant protein and the tick infestation were carried out.
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Exploration of the tick-Borrelia molecular interactions by employing the transcriptomic approaches
MAHMOOD, Sazzad
Along with climate change and increased sharing of habitat, ticks are coming into more frequent contact with humans. The hard tick Ixodes scapularis and Ixodes ricinus are known disease vectors in Northern America and Europe, respectively. Along with many other pathogenic microorganisms, these ticks spread Borrelia sp. by ectoparasitic blood feeding. Borrelia afzelii is the major European Lyme disease pathogen spread by I. ricinus. Our study focuses on differential gene expression in I. ricinus salivary gland and midgut, induced in the nymphal stage by B. afzelii infection. Tick genes upregulated by infection are considered to play essential roles for the acquisition, persistence, and transmission of Borrelia. We have determined 32,897 full length sequences of tick mRNA from B. afzelii infected/noninfected tick salivary glands and the whole body. In addition, we have obtained MACEseq (Massive Analysis of cDNA Ends) from both midgut and salivary glands while the nymphs were non-infected or infected with B. afzelii during three different phases of blood-feeding. From the MACE database, we obtained 250-500 bp 3'-end sequences with raw quantitative expression values. Total reads, unique sequences and protein coding tick genes from midgut samples were 38,199,641, 88,825 and 24,276, and from salivary gland were 74,651,134, 93,096 and 26,179, respectively. After filtering, using several criteria, expression was validated by qPCR. Hence, the validated genes may most likely interact with Borrelia in its acquisition, persistence, or transmission to the vertebrate host. In our study, RNA interference approaches and vaccination were implemented in order to investigate the impact of upregulated tick midgut and salivary gland genes on Borrelia transmission to C3H mice.
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RNA interference in plants
Čermák, Vojtěch ; Fischer, Lukáš (advisor) ; Kulich, Ivan (referee)
The process of RNA interference allows cells to regulate functions of their genes. This process is usually initiated by the presence of double-stranded RNA within a cell. Such double-stranded RNA is diced by a specific protein called Dicer into duplexes of small RNAs, usually 20-25 nucleotides long. Single-stranded small RNAs, released from the duplexes, are the heart of RNA interference and they can be categorize into several groups according to their biogenesis. There are two groups of small RNAs in plants: miRNA and siRNA. Small RNAs can associate with a protein called Argonaut and guide it to the target molecule on the bases of sequence complementarity. The Argonaut-small RNA complex can act on itself or it can interact with other proteins in a wide spectrum of processes. The complex can slice the target mRNA (which can be handled by the sole Argonaut and small RNA), it can suppress translation or it can direct chromatin modifications. The phenomena of RNA interference can be found in almost all Eukaryotes where it can serve many functions, for example it can control cell differentiation, participate in stress responses, direct changes in chromatin and defend the organism against viruses. A diverse set of operating modes of RNA interference can be found in plants, which we are only at the...
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Size matters - siRNAs biogenesis and function in Arabidopsis
Přibylová, Adéla ; Fischer, Lukáš (advisor) ; Honys, David (referee)
RNA interference (RNAi) play a key role in various biological processes including regulation of gens and transposons, phylogenetic of part plant body, stress response, chromatin remodeling and antiviral mechanism. The ground of RNAi is short RNA molecules (small RNA, sRNA). In plants they are produced in range from 21 to 24 nucleotides (nt) and on the basis of being complementary they recognize target molecule of RNAi. It is possible to divide small RNA in two basic classes: microRNAs (miRNA) and small interfering RNAs (siRNA). To product and put small RNA into activate needs proteins from several gene family. DICER-LIKE (DCL) proteins create small RNAs from double-strand RNA precursors, which are often created by RNA dependent RNA polymerase (RDR) activity. With these small RNAs interact ARGONAUTE (AGO) proteins and together create RNA-Induced Silencing Complex (RISC). Those complexes play a key role in recognizing target molecule in active phase of RNAi. Structure and biogenesis of sRNAs has decisive influence on RISC complex and its next way in biogenesis. RNAi cause effect on post-transcriptional level (PTGS), as degradation of target molecule or repression of translation. And on transcriptional level (TGS) as sRNA intermediate histone and DNA methylation.
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Recognition of expressed double-stranded RNAs in mammalian cells
Vaškovičová, Michaela ; Svoboda, Petr (advisor) ; Petr, Jaroslav (referee)
Long double-stranded RNA (dsRNA) is a unique structure formed during viral replication or transcription of repetitive elements. Mammalian cells evolved several mechanisms how to respond to dsRNA. dsRNA can be engaged in one of three pathways: interferon response, RNA editing, and RNA interference (RNAi). RNAi is evolutionary conserved effect of dsRNA, which results in sequence-specific messenger RNA degradation. However, in mammals, RNAi is functional only in mouse oocytes, which express truncated version of Dicer (DicerO ). In somatic cells, dsRNA triggers sequence-independent interferon pathway. The main aim of this Master's thesis was to examine how specific double-stranded RNA-binding proteins (DRBPs) influence distribution of long dsRNA into RNAi and sequence-independent pathways. We used a luciferase-based reporter RNAi assay to monitor sequence-specific and sequence-independent effects of dsRNA co-expressed with selected DRBPs. Our results suggest that none of the tested DRBPs is sufficient to stimulate RNAi in somatic cells. Interestingly, the overexpression of either TARBP2 or PACT suppressed RNAi in cells expressing DicerO . Moreover, microRNA pathway, which employs the same protein factors as RNAi, is not inhibited by TARBP2 or PACT. Therefore, we propose that DRBPs overexpression...
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Substrate cleavage by mammalian Dicer isoforms
Kubíková, Jana ; Svoboda, Petr (advisor) ; Pospíšek, Martin (referee)
Host organisms evolved antiviral responses, which can recognize the viral infection and deal with it. One of the frequent signs of viral infection in a cell is appearance of double-stranded RNA (dsRNA). One of the pathways responding to dsRNA is RNA interference (RNAi), which functions as the key antiviral defence system in invertebrates and plants. Mammals, however, utilize for antiviral defence a different dsRNA-sensing pathway called the interferon response. RNAi functions only in mammalian oocytes and early embryonal stages although its enzymatic machinery is present in all somatic cells, where it is employed in the microRNA pathway. A previous study indicated that the functionality of RNAi in mouse oocytes functions due to an oocyte-specific isoform of protein Dicer (DicerO ), which is truncated at the N-terminus. In my thesis, I aimed to assess whether DicerO processes RNAi substrates more efficiently in vitro than the full-length Dicer (DicerS ), which is found in somatic cells. Therefore, I developed Dicer purification protocol for obtaining both recombinant mouse Dicer isoforms of high purity. I examined their activity in a non-radioactive cleavage assay using RNA substrates with structural features characteristic of RNAi substrates. My results suggest that recombinant DicerO and DicerS do not...
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RNA interference in mouse oocytes and somatic cells
Táborská, Eliška ; Svoboda, Petr (advisor) ; O´Connell, Mary Anne (referee) ; Petr, Jaroslav (referee)
RNA interference (RNAi) is a pathway, which employs Dicer to process long double stranded RNAs (dsRNA) from endogenous or exogenous sources into short interfering RNAs (siRNA). siRNAs are loaded onto Argonaute proteins to mediate sequence-specific post-transcriptional RNA targeting resulting in regulation of protein-coding genes and retrotransposons or antiviral immune response. Another small RNA pathway - PIWI-associated RNA (piRNA) pathway is suppressing retrotransposons in the germline. In mice, canonical RNAi pathway activity is negligible in somatic cells where a full-length Dicer produces gene-regulatory microRNAs (miRNA) but RNAi is highly active in oocytes, which express a truncated oocyte-specific Dicer isoform (DicerO ). DicerO lacks an N-terminal DExD helicase domain and has higher cleavage activity of long dsRNAs. Deletion of oocyte specific DicerO promoter leads to transcriptome aberrations, which include upregulation of putative RNAi targets and MT retrotransposons and, consequently, to meiotic spindle defects and female sterility. In contrast, the piRNA pathway is non-essential in mouse oocytes, potentially because of overlapping functions of RNAi. The PhD thesis aims to understand biological significance of mammalian endogenous RNAi and to explore consequences of re-activated RNAi...
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Modulace sarkosinového metabolismu pomocí RNA interference
Šubrtová, Hana
RNA interference represents a useful tool for modulating expression of sarcosine metabolism genes and for studying the role of sarcosine in prostate cancer. The thesis "Modulation of sarcosine metabolism by RNA interference" summarizes current state-of-the-art of possible regulation of gene expression using various types of nucleic acids. Furthermore the thesis also deals with the issue of the transfer of these regulatory agents to target tissues and finally it describes sarcosine including its involvement in the metabolic cycles of the cell. The main aim of the experimental part of this work was to determine the influence of knock down sarcosine dehydrogenase (SARDH) on other enzymes involved in sarcosine metabolism. This effect was assessed by determining the gene expression of individual genes encoding the four major sarcosine pathway enzymes by quantitative real-time PCR analysis. Experiments were performed on three different prostatic cell line types, PNT1A, DU-145 and PC3. The most significant differences on level of gene expression were observed in carcinoma cells DU-145 in which a significant increase in gene expression of dimethylglycine dehydrogenase (DMGHD) and sarcosine oxidase (PIPOX) was observed after applications of siRNA targeting the SARDH.
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