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SWI2/SNF2 ATPases with a focus on the ISWI subfamily: protein complexes and mouse models for their study
Turková, Tereza ; Stopka, Tomáš (advisor) ; Janoštiak, Radoslav (referee)
In the nucleus the DNA is packed along with proteins into a dynamic structure called chromatin. During cell cycle the chromatin structure becomes a subject to various changes. During interphase chromatin structure becomes loose while shortly before cell division it undertakes the form of highly condensed mitotic chromosomes. Structure of chromatin influences significantly mode of gene expression and its pattern. DNA-binding proteins interacting within chromatin are also necessary during this process. To gain the access to the DNA binding factors, the chromatin has to be in a loosened form. As long as the structure of the chromatin is more condensed it creates a barrier for the DNA binding proteins. Therefore it becomes obvious that the remodeling of the chromatin structure is one of the important regulators of gene expression and that the enzymes, which execute remodeling, are of great importance. One of them is ATPase Smarca5, which belongs to the protein subfamily ISWI and which creates the catalytic subunit for several different ATP-dependent chromatin remodeling complexes. Mutations of members of those complexes disturb regulation of transcription and cellular differentiation. In some cases the incorrect function of these complexes can lead to cellular transformation into a tumours state. This...
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Role of Smarca5 (Snf2h) chromation remodeling ATPase in hematopoitic development and erythropoiesis
Kokavec, Juraj ; Stopka, Tomáš (advisor) ; Divoký, Vladimír (referee) ; Kořínek, Vladimír (referee)
The Imitation Switch (ISWI) nuclear ATPase Smarca5 (Snf2h) is one of the most conserved chromatin remodeling factors. It exists in a variety of oligosubunit complexes that move DNA with respect to the histone octamer to generate regularly spaced nucleosomal arrays. Smarca5 interacts with different accessory proteins and represents a molecular motor for DNA replication, repair and transcription. We deleted Smarca5 at the onset of definitive hematopoiesis (Vav1-iCre) and observed that animals die during late fetal development due to anemia. Hematopoietic stem and progenitor cells (HSPCs) accumulated but their maturation towards erythroid and myeloid lineages was inhibited. Proerythroblasts were dysplastic while basophilic erythroblasts were blocked in G2/M and depleted. Smarca5 deficiency led to increased p53 levels, its activation at two residues, one associated with DNA damage (S-18) second with CBP/p300 (K376Ac), and finally activation of the p53 targets. We also deleted Smarca5 in committed erythroid cells (Epor-iCre) and observed that animals were anemic postnatally. Furthermore, 4- OHT-mediated deletion of Smarca5 in the ex vivo cultures confirmed its requirement for erythroid cell proliferation. Thus, Smarca5 plays indispensable roles during early hematopoiesis and erythropoiesis.
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Epigenetic Aspects of normal and malignant hematopoiesis: role of chromatin remodeling ISWIATPase.
Zikmund, Tomáš ; Stopka, Tomáš (advisor) ; Dráber, Peter (referee) ; Otáhal, Pavel (referee)
Chromatin remodeling protein Smarca5 participates on many cellular processes, which are important for tissue development and tumorigenesis. Among these processes utilizing ATPase activity of Smarca5 belong also transcription, replication and DNA repair. We hypothesized that Smarca5 represents essential molecule for chromatin modulation primarily at early developmental stages at the level of fast-dividing progenitors of many origins, in whose the ATPase is highly expressed. To such tissues may belong also hematopoiesis, in which the Smarca5 has highest expression. The subject of my doctoral thesis is therefore analysis of the effect Smarca5 depletion on proliferation and differentiation of hematopoietic progenitors in vivo and a search for mechanisms behind the resulted developmental defects. We utilized conditionally knockout allele of Smarca5 in blood precursors to study in a mouse model how depletion of the ISWI ATPase causes accumulation of earliest progenitors inhibited from further maturation to erythroid and other myeloid lines. The proerythroblasts became dysplastic and the majority of basophilic erythroblasts ceased cycling around the G2/M stage. An expected mechanism for observed changes appeared the activation of stress pathway of protein p53 that is often associated with unrepaired DNA...
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Role of Smarca5 (Snf2h) chromation remodeling ATPase in hematopoitic development and erythropoiesis
Kokavec, Juraj ; Stopka, Tomáš (advisor) ; Divoký, Vladimír (referee) ; Kořínek, Vladimír (referee)
The Imitation Switch (ISWI) nuclear ATPase Smarca5 (Snf2h) is one of the most conserved chromatin remodeling factors. It exists in a variety of oligosubunit complexes that move DNA with respect to the histone octamer to generate regularly spaced nucleosomal arrays. Smarca5 interacts with different accessory proteins and represents a molecular motor for DNA replication, repair and transcription. We deleted Smarca5 at the onset of definitive hematopoiesis (Vav1-iCre) and observed that animals die during late fetal development due to anemia. Hematopoietic stem and progenitor cells (HSPCs) accumulated but their maturation towards erythroid and myeloid lineages was inhibited. Proerythroblasts were dysplastic while basophilic erythroblasts were blocked in G2/M and depleted. Smarca5 deficiency led to increased p53 levels, its activation at two residues, one associated with DNA damage (S-18) second with CBP/p300 (K376Ac), and finally activation of the p53 targets. We also deleted Smarca5 in committed erythroid cells (Epor-iCre) and observed that animals were anemic postnatally. Furthermore, 4- OHT-mediated deletion of Smarca5 in the ex vivo cultures confirmed its requirement for erythroid cell proliferation. Thus, Smarca5 plays indispensable roles during early hematopoiesis and erythropoiesis.
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SWI2/SNF2 ATPases with a focus on the ISWI subfamily: protein complexes and mouse models for their study
Turková, Tereza ; Stopka, Tomáš (advisor) ; Janoštiak, Radoslav (referee)
In the nucleus the DNA is packed along with proteins into a dynamic structure called chromatin. During cell cycle the chromatin structure becomes a subject to various changes. During interphase chromatin structure becomes loose while shortly before cell division it undertakes the form of highly condensed mitotic chromosomes. Structure of chromatin influences significantly mode of gene expression and its pattern. DNA-binding proteins interacting within chromatin are also necessary during this process. To gain the access to the DNA binding factors, the chromatin has to be in a loosened form. As long as the structure of the chromatin is more condensed it creates a barrier for the DNA binding proteins. Therefore it becomes obvious that the remodeling of the chromatin structure is one of the important regulators of gene expression and that the enzymes, which execute remodeling, are of great importance. One of them is ATPase Smarca5, which belongs to the protein subfamily ISWI and which creates the catalytic subunit for several different ATP-dependent chromatin remodeling complexes. Mutations of members of those complexes disturb regulation of transcription and cellular differentiation. In some cases the incorrect function of these complexes can lead to cellular transformation into a tumours state. This...
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