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Evolution of the gene regulatory network underlying the formation of the gastrula organizer
Macháčová, Simona ; Kozmikova, Iryna (advisor) ; Krylov, Vladimír (referee) ; Buchtová, Marcela (referee)
During gastrulation, the vertebrate embryo is organized from the clump of cells into a bilaterally symmetric body. This organization process is driven by the gastrula organizer. Its establishment is induced by maternal Wnt/β-catenin signaling and Nodal/Activin signaling localized in the presumptive dorsal region of the embryo. The regulative environment then triggers the expression of the organizer-specific genes which create morphogen gradients in the embryonic body and therefore give each cell positional information. However, the evolution of vertebrate organizer establishment remains vague. Here we aim to test the compatibility of the invertebrate cis-regulatory modules with the vertebrate gene regulatory network (GRN). We introduced fluorescent reporter genes under the control of the invertebrate regulatory sequence of organizer-specific genes into a vertebrate model to observe their behavior in the context of the vertebrate GRN. We found and functionally verified a 500 bp-long amphioxus sequence (an enhancer) that is necessary and sufficient to drive a correct Chordin gene expression in the gastrula organizer in zebrafish. Chordin is a prominent organizer-specific gene antagonizing Bone Morphogenetic Protein (BMP) signaling. We tested also other invertebrate genes for their compatibility with...
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Regulatory mechanisms of ornithin transcarbamylase and beta-glucocerebrosidase gene expression and their relevance to diagnostics
Lukšan, Ondřej ; Jirsa, Milan (advisor) ; Kožich, Viktor (referee) ; Kříž, Vítězslav (referee)
5 Abstract Definitive diagnosis of inherited metabolic disorders commonly depends on the measurement of enzyme activity (which is often complicated) and/or molecular genetic testing. Yet even the standard mutation analysis can bring false negative results in the case of gross chromosomal rearrangements or incorrect regulation of gene expression due to the mutations in regulatory regions. In the present study I focused on characterization of complex mutations affecting the gene encoding ornithin transcarbamylase (OTC) followed by studies of regulatory regions of OTC and GBA (the gene encoding β-glucocerebrosidase). In the first study we identified 14 novel mutations including three large deletions in a cohort of 37 patients with OTC deficiency (OTCD). Subsequently we evaluated clinical significance of all these mutations. We also found a heterozygote carrying a hypomorphic mutation and manifesting OTCD most likely due to unfavorable X-inactivation which was observed independently in three different peripheral tissues. In order to evaluate the clinical significance of a promoter variation c.-366A>G found in a family with mild OTCD we identified three alternative transcription start sites (TSSs) of human OTC and delimited the promoter. We also found a distal enhancer and performed functional analysis of both...
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Model for study of transcription regulation of granulocytic genes MPO and MMP9 by different levels of PU.1 transcription factor
Chramostová, Kamila ; Pospíšil, Vít (advisor) ; Kleibl, Zdeněk (referee)
9 Abstract Enhancers are distal cis - regulatory DNA sequences that regulate (enhance) transcription of the respective gene driven by its promoter. Enhancers are found in non-coding DNA upstream or downstream of the gene coding sequence, or in introns or coding regions that are located up to hundreds kb away from the gene. Superenhancers are newly discovered clusters of multiple enhancers that play a vital role in activating tissue-specific genes, determining cell identity and regulating differentiation. PU.1 is the transcription factor (TF) that is necessary for normal haematopoiesis, specifically for the development of myeloid and lymphoid blood lineages. Distinct levels of PU.1 induce differentiation of hematopoietic cells into different cell lineages whereby disruption of PU.1 levels leads to leukemogenesis. High PU.1 levels stimulate macrophage development, while intermediate levels stimulate the development of granulocytes. This diploma thesis seeks to contribute to addressing the interesting biological question of what are the regulatory mechanisms to ensure that granulocytic genes are activated only at the intermediate concentration of PU.1, whereas macrophage genes are activated only at its high levels. The aim of this diploma thesis was to create a series of reporter vectors carrying regulatory...
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Regulatory mechanisms of ornithin transcarbamylase and beta-glucocerebrosidase gene expression and their relevance to diagnostics
Lukšan, Ondřej ; Jirsa, Milan (advisor) ; Kožich, Viktor (referee) ; Kříž, Vítězslav (referee)
5 Abstract Definitive diagnosis of inherited metabolic disorders commonly depends on the measurement of enzyme activity (which is often complicated) and/or molecular genetic testing. Yet even the standard mutation analysis can bring false negative results in the case of gross chromosomal rearrangements or incorrect regulation of gene expression due to the mutations in regulatory regions. In the present study I focused on characterization of complex mutations affecting the gene encoding ornithin transcarbamylase (OTC) followed by studies of regulatory regions of OTC and GBA (the gene encoding β-glucocerebrosidase). In the first study we identified 14 novel mutations including three large deletions in a cohort of 37 patients with OTC deficiency (OTCD). Subsequently we evaluated clinical significance of all these mutations. We also found a heterozygote carrying a hypomorphic mutation and manifesting OTCD most likely due to unfavorable X-inactivation which was observed independently in three different peripheral tissues. In order to evaluate the clinical significance of a promoter variation c.-366A>G found in a family with mild OTCD we identified three alternative transcription start sites (TSSs) of human OTC and delimited the promoter. We also found a distal enhancer and performed functional analysis of both...
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