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Identification of new tissue-specific interaction partners of chromatin remodelling ATPase Smarca5
Arishaka, Yuliia ; Kokavec, Juraj (advisor) ; Děd, Lukáš (referee)
The regulation of chromatin structure is fundamental to a wide range of cellular processes, including transcriptional regulation, cell division, differentiation and DNA damage repair, and ATP-dependent chromatin remodeling complexes have been established as essential components of this regulatory network. Smarca5, as an ATPase/Helicase enzyme, has been shown to regulate chromatin structure by interacting with bromodomain and DDT-WHIM domain-containing partners to control the binding of chromatin-associated proteins and transcription factors to their specific DNA target sequences. In this work we identify a previously undescribed protein with a conserved N-terminal bromodomain and ISWI protein binding DDT-WHIM domain through co-immunoprecipitation and mass spectrometry in mammalian cell lines and establish it as a novel interaction partner of chromatin remodeling ATPase Smarca5. Furthermore, we have pinpointed the region required for Smarca5 interaction that corresponds to DDT-WHIM domain. We have furthermore attempted to identify additional interaction partners which may hint on the potential function of this novel chromatin complex and validated its expression in embryonic and postnatal tissues. This discovery represents a unique opportunity for further investigation into its potential function in...
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Research of epigenetic aspects of hematopoietic and spermatogenesis stem cells.
Hybešová, Michaela ; Pimková, Kristýna (advisor) ; Děd, Lukáš (referee)
Stem cell differentiation is controlled by coordinated regulation of gene transcription. One of the regulatory factors is the loosening of chromatin and the accessibility of DNA to transcription factors. Chromatin remodeling is mediated by remodeling complexes. The ISWI chromatin remodeling ATPase Smarca5 (S5) is an important factor of remodeling complexes. It is a highly conserved chromatin-remodeling factor forming a catalytic subunit that can be found in several oligosubunit complexes. In these complexes, it actively regulates nucleosome structure and remodeling during DNA replication, repair and transcription. S5 has been identified as a key protein in embryonic development. Its deficiency leads to defects in hematopoiesis and male genital development. In the presented study, we focused on the role of S5 in hematopoiesis and spermatogenesis. Using a mouse model with transgenic expression of S5, co-immunoprecipitation and mass spectrometry, we identified S5 complexes in hematopoietic and testicular cells. We also studied the phenotypic consequences of S5 deficiency in mouse testes and found that it leads to impaired sperm development and male sterility. Using transcriptomic and proteomic analysis, we identified several molecular programs that could lead to reproductive disorders. Our work...
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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) during transcription of transfected DNA template.
Zikmund, Tomáš ; Stopka, Tomáš (advisor) ; Smetana, Karel (referee)
Cellular and tissue characteristics are results of dynamic regulation of gene expression. DNA wrapped into proteins, referred to as chromatin, requires involvement of mechanisms guiding accessibility of specific sequences. In higher organisms, chromatin remodeling proteins are indispensable in regulating chromatin structure including ISWI ATPase SMARCA5. SMARCA5 is involved in almost any transaction on DNA including transcription, however precise in vivo role of SMARCA5 in these processes remains unknown. To advance understanding of specific role of SMARCA5 in the development of chromatin structure during transcription we devised cellular model in which SMARAC5 level is manipulated while chromatin structure development and transcriptional response are monitored. Our data indicate that the transfected DNA template that is transcribed is enriched with histone H3 and its specific methylation of Histone H3 lysine (K) 4, a mark of active chromatin structure. Overexpression of SMARCA5 results within the reporter gene coding sequence in ~2,5-3 fold increase of both H3 occupancy an its modification H3K4Me3. Increased DNA template commitment into chromatinization is associated with repression of reporter gene expression. These results are supported by studies indicating dynamic development of nucleosomal...
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Production and analysis of cellular conditional inactivation models of the ISWI ATPase Smarca5
Tauchmanová, Petra ; Stopka, Tomáš (advisor) ; Burda, Pavel (referee)
The eukaryotic nuclear processes such as replication, DNA damage repair (DDR) and transcription are highly dependent on the regulation of chromatin structure. The dynamic changes in chromatin accessibility are controlled by a class of chromatin-remodeling factors which form multimeric complexes and use ATP as the source of their helicase activity. In this study we have established a mouse embryonic fibroblast in vitro model with conditional inactivation of chromatin remodeling ATPase Smarca5 and used this powerful tool to test the regulation of cell cycle, proliferation and DDR signaling in conditions with low Smarca5 activity. Our results show that decreased dosages lead to decreased proliferation apparent already within few days post induction of Smarca5 deletion that is accompanied with decrease of cells in S and M phases of cell cycle, increasing cell ploidy and accelerated cell senescence. Additionally, the Smarca5 depleted cells upregulated many protein markers associated with DNA damage and cellular stress. Our results thus indicate that Smarca5 has indispensable roles during cell proliferation including in the maintenance of genome integrity during S phase of cell cycle.
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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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Production and analysis of cellular conditional inactivation models of the ISWI ATPase Smarca5
Tauchmanová, Petra ; Stopka, Tomáš (advisor) ; Burda, Pavel (referee)
The eukaryotic nuclear processes such as replication, DNA damage repair (DDR) and transcription are highly dependent on the regulation of chromatin structure. The dynamic changes in chromatin accessibility are controlled by a class of chromatin-remodeling factors which form multimeric complexes and use ATP as the source of their helicase activity. In this study we have established a mouse embryonic fibroblast in vitro model with conditional inactivation of chromatin remodeling ATPase Smarca5 and used this powerful tool to test the regulation of cell cycle, proliferation and DDR signaling in conditions with low Smarca5 activity. Our results show that decreased dosages lead to decreased proliferation apparent already within few days post induction of Smarca5 deletion that is accompanied with decrease of cells in S and M phases of cell cycle, increasing cell ploidy and accelerated cell senescence. Additionally, the Smarca5 depleted cells upregulated many protein markers associated with DNA damage and cellular stress. Our results thus indicate that Smarca5 has indispensable roles during cell proliferation including in the maintenance of genome integrity during S phase of cell cycle.
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Epigenetic factors CTCF a SMARCA5 control expression of hematopoietic transcription factor SPI1 in cells of acute myeloid leukemia and myelodysplastic syndrome.
Dluhošová, Martina ; Stopka, Tomáš (advisor) ; Machová Poláková, Kateřina (referee) ; Kozák, Tomáš (referee)
CCCTC-binding factor (CTCF) can both activate as well as inhibit transcription by forming chromatin loops between regulatory regions and promoters. In this regard, Ctcf binding on the non-methylated DNA and its interaction with the Cohesin complex results in differential regulation of the H19/Igf2 locus. Similarly, a role for CTCF has been established in normal hematopoietic development; however its involvement, despite mutations in CTCF and Cohesin complex were identified in leukemia, remains elusive. CTCF regulates transcription dependently on DNA methylation status and can if bound block interactions of enhancers and promoters. Here, we show that in hematopietic cells CTCF binds to the imprinting control region of H19/Igf2 and found that chromatin remodeller Smarca5, which also associates with the Cohesin complex, facilitates Ctcf binding and regulatory effects. Furthermore, Smarca5 supports CTCF functionally and is needed for enhancer-blocking effect at imprinting control region. We identified new CTCF-recognized locus near hematopoietic regulator SPI1 (PU.1) in normally differentiating myeloid cells together with members of the Cohesin complex. Due to DNA methylation, CTCF binding to the SPI1 gene is reduced in AML blasts and this effect was reversible by DNA methylation inhibitor 5-azacitidine.
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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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