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Identification and characterization of novel regulators of hematopoietic stem cell function
Grušanović, Srđan ; Alberich Jorda, Meritxell (advisor) ; Balounová, Jana (referee) ; Froňková, Eva (referee)
Hematopoietic stem cells (HSCs) are sitting atop a carefully orchestrated system, called the hematopoietic system. HSCs maintain the constant production of mature blood cells throughout our life, and dysregulated HSC function may lead to severe health problems including bone marrow aplasia and leukemia. Thus, HSC activity needs to be tightly controlled by a complex network of cell intrinsic and cell extrinsic factors. In this thesis, we focus on two previously uncharacterized extrinsic mechanisms that might be involved in the regulation of HSC function. A common aspect of these mechanisms is the production of pro-inflammatory cytokines. First, we investigated the impact of donor NK cells on donor HSC function upon bone marrow transplantation, a frequent clinical intervention. We observed that NK cells negatively affect HSC engraftment and reconstitution during transplantation. To address the potential mechanism, we employed Cebpg knockout mice, which produce non-functional NK cells, and determined that NK cells affect HSC activity through the production of IFNγ. Remarkably, IFNγ-blocking antibodies improved murine and human HSC activity upon bone marrow transplantation. Altogether, we concluded that suppression of inflammatory signals generated by donor innate immune cells can have a significant...
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Identification and functional characterization of C/EBPalpha targets in normal and malignant hematopoiesis
Zjablovskaja, Polina ; Alberich Jorda, Meritxell (advisor) ; Stopka, Tomáš (referee) ; Fuchs, Ota (referee)
Thehematopoieticsystemisahighlyorganizedstructure, whichhastobetightly regulatedinordertofunctionproperly.Abnormalitiesinhematopoieticdevelopmentmaylead tohematologicaldisorders,suchasacutemyeloidleukemia(AML).Thefunctionalityofthe hematopoieticsystemlargelyreliesontranscriptionfactors.C/EBPtranscriptionfactoris knownasoneofthe majorhematopoieticregulators,requiredforthefunctionalityof hematopoieticstemcellsaswellasformyeloidlineagedevelopment.Importantly,C/EBP expressionisalteredinalargeproportionofAMLcases.C/EBPregulateshematopoiesis mainlythroughorchestratingexpressionofitstargetgenes.ManyoftheC/EBPtargetshave previouslybeenshowntoplayaroleinthehematopoieticsystemandtobeinvolvedin leukemictransformation. That makesidentificationofnovel C/EBP targetsandtheir functionalcharacterizationanexcitingsubjectofresearch.Hereweidentifiedalistofgenes whoseexpressiondependsontheactivityofC/EBPthesocalledC/EBPsignature. We demonstratedthattreatment withhistonedeacetylase(HDAC)inhibitorsreactivatesthe expressionofthesegenesincellswithnon-functionalC/EBP.Inaddition,wedemonstrated thattreatmentwiththeHDACinhibitorspromotesmyeloiddifferentiationinAMLsamples carryingbi-allelicCEBPA mutationsandcharacterizedbythereducedexpressionofthe...
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Regulatory mechanisms in normal and malignant granulopoiesis
Kardošová, Miroslava ; Alberich Jorda, Meritxell (advisor) ; Stopka, Tomáš (referee) ; Balounová, Jana (referee)
Neutrophils, known primarily as key players in defense against invading pathogens, represent an essential component of both the innate and adaptive immunity. Continuous production of large quantities of neutrophils is ensured by a complex process termed granulopoiesis. In order to maintain a stable neutrophilic population, granulopoiesis requires to be tightly regulated. Moreover, impaired granulopoiesis may lead to aberrant bone marrow function and, ultimately, give rise to acute myeloid leukemia (AML). Despite decades of research, the mechanisms regulating granulopoiesis are still unclear. In particular, the CCAAT/enhancer binding protein (C/EBP) family of transcription factors plays a critical role in this process. C/EBPα acts as a master regulator of granulopoiesis mainly by orchestrating expression of its target genes, which will mediate granulocytic differentiation. Thus, characterization of novel C/EBPα target genes is critical for a better understanding of the molecular mechanisms that regulate granulopoiesis. Previously, we showed that another C/EBP member, CEBPG, is a direct target of C/EBPα. In the first part of the present work, we addressed the unknown role of C/EBPγ in granulopoiesis. We observed that Cebpg conditional knockout (KO) mice, which have the Cebpg gene ablated specifically...
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The transcription factor C/EBPƴ as a novel regulator in mast cell development and function
Jedlička, Marek ; Alberich Jorda, Meritxell (advisor) ; Černý, Jan (referee)
Mast cells contribute to the activities of innate and adaptive branches of the immune system. They participate in pro-inflammatory responses to a wide range of pathogens, such as parasites, bacteria, and other foreign agents. These beneficial properties are in contrast to the contribution of mast cells to certain pathologies, such as asthma, allergy, autoimmune disorders, anaphylaxis, and systemic mastocytosis. Thorough knowledge of mast cell biology in health and disease is critical for the development of new therapeutic approaches. However, molecular mechanisms that control mast cell development and function are still incompletely defined. Our preliminary data indicate that the transcription factor C/EBP is a key player in mast cell biology. Here, using in vitro and in vivo models, we determine how C/EBP regulates the commitment of hematopoietic progenitors towards mast cells, and modulates mast cells function. These efforts provide novel insights to the role of C/EBP in hematopoiesis, and contribute to a better understanding of the mechanisms governing mast cell biology. Key words Mast cells, C/EBP, transcription factors, bone marrow-derived mast cell cultures, mast cell development, Cebpg conditional knockout mice
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Identification of novel mechanisms controlling emergency granulopoiesis in hematopoietic stem and progenitor cells
Vaníčková, Karolína ; Alberich Jorda, Meritxell (advisor) ; Zadražil, Zdeněk (referee)
Granulocytes represent the first line of defense against bacteria and fungi. Daily production of granulocytes is sustained by steady state granulopoiesis but under stress (e.g., bacterial infection) this program switches to emergency granulopoiesis (EG) which ensures the production of granulocytes at enhanced and accelerated rates. Very little is known about the regulation of EG. In this thesis, we showed that disruption of the β-catenin-TCF/LEF mediated transcription impairs EG in vivo. Further, we demonstrated that lipopolysaccharide (LPS) administration in mice induces accumulation of active β-catenin in hematopoietic stem and progenitor cells (HSPCs) as early as 4 hours (H) after stimulation, with highest increase at 24H. This effect was at least partially mediated in a niche independent manner, since LPS stimulation in vitro induced β-catenin accumulation in c-Kit+ cells after 2H, with a peak activation at 4H. Using single cell RNA sequencing, we determined the cell cluster dynamics of HSPCs following 4H LPS stimulation. Interestingly, we identified a possible upstream activator of β- catenin in one of the clusters - Wnt10b. Indeed, Wnt10b showed a similar expression pattern as EG master regulator Cebpb and β-catenin activation, following in vitro treatment with LPS. Altogether, our data point...
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Identification and characterisation of novel mechanisms regulating steady state and emergency granulopoiesis
Daněk, Petr ; Alberich Jorda, Meritxell (advisor) ; Fuchs, Ota (referee) ; Balounová, Jana (referee)
ABSTRACT Neutrophils are essential cells of the immune system. They engage in pathogen clearance, inflammatory response, and wound healing. Proper production and activation of neutrophils is critical for the health of an individual, since several disorders are related to neutrophilic alterations. In this thesis, we explore three previously uncharacterized mechanisms that might be involved in the regulation of neutrophilic differentiation. First, we addressed the role of the canonical Wnt signaling pathway. This signaling is executed by interaction of -catenin with TCF/LEF transcription factors. We employed a murine model that specifically inactivates -catenin-TCF/LEF-mediated transcription by expressing a dominant negative form of TCF4 (dnTCF4). Using this model in combination with several in vitro and in vivo assays we demonstrated that -catenin-TCF/LEF signaling directly upregulates expression of G-CSF receptor in hematopoietic progenitors, imposing myeloid commitment and favoring neutrophilic differentiation. This appeared to be especially important during the response to systemic infection, termed emergency granulopoiesis, as dnTCF4-expressing mice showed high susceptibility to Candida albicans infection. Remarkably, the critical role of -catenin-TCF/LEF signaling for neutrophil differentiation...
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Regulatory mechanisms in normal and malignant granulopoiesis
Kardošová, Miroslava ; Alberich Jorda, Meritxell (advisor) ; Stopka, Tomáš (referee) ; Balounová, Jana (referee)
Neutrophils, known primarily as key players in defense against invading pathogens, represent an essential component of both the innate and adaptive immunity. Continuous production of large quantities of neutrophils is ensured by a complex process termed granulopoiesis. In order to maintain a stable neutrophilic population, granulopoiesis requires to be tightly regulated. Moreover, impaired granulopoiesis may lead to aberrant bone marrow function and, ultimately, give rise to acute myeloid leukemia (AML). Despite decades of research, the mechanisms regulating granulopoiesis are still unclear. In particular, the CCAAT/enhancer binding protein (C/EBP) family of transcription factors plays a critical role in this process. C/EBPα acts as a master regulator of granulopoiesis mainly by orchestrating expression of its target genes, which will mediate granulocytic differentiation. Thus, characterization of novel C/EBPα target genes is critical for a better understanding of the molecular mechanisms that regulate granulopoiesis. Previously, we showed that another C/EBP member, CEBPG, is a direct target of C/EBPα. In the first part of the present work, we addressed the unknown role of C/EBPγ in granulopoiesis. We observed that Cebpg conditional knockout (KO) mice, which have the Cebpg gene ablated specifically...
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Molecular basis of clonal heterogeneity of hematological diseases
Babošová, Oľga ; Láníková, Lucie (advisor) ; Alberich Jorda, Meritxell (referee) ; Horváthová, Monika (referee)
Tumor heterogeneity has been recognized for decades. The molecular mechanisms impacting clonal heterogeneity in hematological diseases, specifically myeloproliferative neoplasms (MPN) and mantle cell lymphoma, with the focus on several inherited genetic factors, inflammation, the protective mechanisms of DNA damage response (DDR) in the leukemic transformation and the treatment strategies are the focus of this thesis. Firstly, I focus on studying germline JAK2 variants and how these may influence the initiation and progression of MPN diseases, and even contribute to further genomic alterations in the mutated clone. A study performed by our cooperating lab in Utah, USA,1 analyzing the mutational landscape of 31 JAK2 V617F-positive polycythemia vera (PV) patients identified two novel germline mutations in JAK2 gene, JAK2 T108A and JAK2 L393V. Another study2 , performed by our cooperating lab in Olomouc, Czech Republic, characterized two germline JAK2 mutations, E846D and R1063H, in a case of hereditary erythrocytosis accompanied by megakaryocytic atypia. The JAK2 R1063H variant was initially described in 3 out of 93 PV patients that were JAK2 V617F-positive.3 Our aim was to identify the role of selected inherited mutations in JAK2 gene in the initiation and progression of myeloproliferative...
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The transcription factor C/EBPƴ as a novel regulator in mast cell development and function
Jedlička, Marek ; Alberich Jorda, Meritxell (advisor) ; Černý, Jan (referee)
Mast cells contribute to the activities of innate and adaptive branches of the immune system. They participate in pro-inflammatory responses to a wide range of pathogens, such as parasites, bacteria, and other foreign agents. These beneficial properties are in contrast to the contribution of mast cells to certain pathologies, such as asthma, allergy, autoimmune disorders, anaphylaxis, and systemic mastocytosis. Thorough knowledge of mast cell biology in health and disease is critical for the development of new therapeutic approaches. However, molecular mechanisms that control mast cell development and function are still incompletely defined. Our preliminary data indicate that the transcription factor C/EBP is a key player in mast cell biology. Here, using in vitro and in vivo models, we determine how C/EBP regulates the commitment of hematopoietic progenitors towards mast cells, and modulates mast cells function. These efforts provide novel insights to the role of C/EBP in hematopoiesis, and contribute to a better understanding of the mechanisms governing mast cell biology. Key words Mast cells, C/EBP, transcription factors, bone marrow-derived mast cell cultures, mast cell development, Cebpg conditional knockout mice
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Characterization of hematopoietic cells in patients with mature B-cell malignancies
Maswabi, Bokang Calvin ; Živný, Jan (advisor) ; Otáhal, Pavel (referee) ; Alberich Jorda, Meritxell (referee)
(English) Using flow cytometry we analyzed absolute and relative proportions of hematopoietic stem and progenitors cells (HSPC) populations including hematopoietic stem cells (HSC), multipotent progenitors (MPP), multilymphoid progenitors (MLP) and pro B cells from bone marrow of patients with mature B cell malignancies and in healthy controls. We found lower absolute and relative numbers of MLP and higher relative numbers of HSC were observed in patients when compared to age-matched controls irrespective of bone marrow (BM) involvement. On the other hand significantly decreased absolute numbers of MPP were observed only in patients who had their BM infiltrated by disease. We also confirmed published data showing increasing absolute and relative percentages of MLP with increasing age, decreasing relative percentages of HSC with increasing age, and decreasing absolute and relative pro B cell frequencies with increasing age in healthy subjects. While decreased absolute and relative pro B cell numbers were also found in patient samples as age increased, no significant correlations were detected in patients HSC, MPP or MLP populations. Age-related sub-analysis of PTs samples demonstrated that most of the disease associated changes in HSPC frequencies were observable more prominently in the elderly (>45...
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