|
|
Role of transcription factors MEIS in the origin and development of the neural crest
Fábik, Jaroslav ; Machoň, Ondřej (advisor) ; Buchtová, Marcela (referee) ; Procházka, Jan (referee)
Unique to the vertebrate embryo, neural crest cells represent a multipotent cell population that migrates throughout the body and gives rise to a multitude of different types of cells and tissues. Cranial neural crest cells populate the developing pharyngeal arches and establish skeletogenic condensations that generate the future bones and cartilages of the face and neck. Moreover, these cells send out and receive signals from adjacent tissues of non-neural crest origin, such as the mandibular epithelium and muscle precursor cells. Such reciprocal interactions give rise to organs and structures, for instance, to the tongue. The aim of this work was to elucidate the roles of homeodomain-containing MEIS transcription factors in neural crest cells and in craniofacial development, by using a mouse model with conditional inactivation of Meis2 gene in neural crest cells. We show that transcription factor MEIS2 is expressed in the medial region of the developing mandible and in the developing tongue. Conditional Meis2 inactivation using the Wnt1-Cre2 mouse strain caused mandible and tongue hypoplasia, and ectopic bone formation at the expense of tongue development. These mandibular arch anomalies were accompanied by the loss of Hedgehog signaling in the mandibular epithelium, expanded RUNX2 expression in...
|
|
|
Molecular interaction of developing axons with the surface ectoderm
Matějček, Miroslav ; Machoň, Ondřej (advisor) ; Rozbeský, Daniel (referee)
The complex of cranial nerves consists of twelve pairs of nerves, which connect organs of the head with the central nervous system. One of the organs, which are innervated by cranial nerves are whiskers (also known as vibrissae). Whiskers are special type of mammalian hairs, which are innervated by the infraorbital branch of trigeminal nerve. These hairs provide information necessary for orientation in terrain, localisation of prey and locomotion. The potential role of axons in whiskers development has been discussed for many years. However, this hypothesis has not yet been confirmed. In this research we have used murine strains Neurog1 KO and Meis2 cKO with either abnormal or completely missing trigeminal nerve. Thanks to the analysis of embryonic development in these strains we have denied our hypothesis, that axons of trigeminal nerve serve a role in initiation of whisker follicles. In Meis2 cKO embryos we observed malfunction in formation of whisker follicles. The expression of Meis2 during the development of whiskers has an influence on various signalling cascades including Fgf, Shh and Bmp. In regards to changes in mentioned signalling cascades we suggest that the whisker follicle development is altered between the first dermal and first epidermal signal.
|
|
|
Migration and morphogenesis of neural crest cells in the context of craniofacial development of selected ray-finned fishes
Štundl, Jan ; Černý, Robert (advisor) ; Buchtová, Marcela (referee) ; Machoň, Ondřej (referee)
Neural crest (NC) cells play a crucial role in vertebrate development and evolution. This cell population contributes to many new cell types such as chondrocytes and osteocytes of the head skeleton, neurons, pigment cells, cardiomyocytes, and many others. As such the neural crest is often considered as the fourth germ layer. This vertebrate-specific cell population emerges during formation of the neural tube. Whereas in the trunk region NC cells migrate as separate cells, cranial neural crest (CNC) cells extensively migrate in three discrete streams forming most of the head mesenchyme. In all vertebrates, CNC stereotypically follows the tripartite pattern of migration along the anteroposterior axis so that the most anterior (trigeminal) stream emerges first, followed by the hyoid and branchial CNC streams. In this work, I have studied representatives of all three lineages of non-teleost fishes (bichir, sturgeon, and gar) and also one species from the crown group of ray-finned fishes, the pike. The main question I addressed in my project was whether the CNC cells stereotypically follow a tripartite pattern of migration along the anteroposterior axis as is seen throughout vertebrates. Surprisingly, I found several alterations in the emergence of CNC cells and their migratory pattern in the studied...
|
|
|
Molecular genetic approaches used in preimplantation genetic analysis of human embryos in assisted reproduction
Limbergová, Jana ; Machoň, Ondřej (advisor) ; Šimoník, Ondřej (referee)
Preimplantation genetic testing is one of the main clinical procedures that take place in assisted reproduction centres around the world. It is sought after by couples for many different reasons. The causes of problems may relate to hereditary diseases that potential parents do not wish to pass on to their offspring, or may include the risk of transmission of chromosomal alterations. In addition, infertility may be caused by an increased risk of embryo aneuploidy, which correlates with mother's increased age and other factors that this bachelor thesis discusses. The bachelor thesis also focuses on up-to-date approaches to cytogenetic examinations for reproductive genetics and discusses recent clinical molecular methods that are used to improve the diagnosis and therapy of infertile couples. These are, for example, microarray methods, quantitative real-time PCR or next-generation sequencing and methods of whole-genome amplification. This work also summarizes methods that are gradually being abandoned, e.g. fluorescent in situ hybridization, and compares their advantages and disadvantages. Key words: preimplantation genetic testing, aneuploidy, structural rearrangements, monogenic diseases, biopsy, fluorescent in situ hybridization, microarray methods, comparative genomic hybridization, quantitative...
|
|
|
Genetic regulation of the cranial cartilage and bone development
Burianová, Andrea ; Machoň, Ondřej (advisor) ; Kaucká, Markéta (referee)
The skull development is an elaborate sequence of cellular processes, featuring two distinct tissue lineages, a unique transient pluripotent population of neural crest cells and mesodermal cells. Several differences in molecular mechanisms operating during chondrogenesis and skeletogenesis have been demonstrated in cranial bones originating from these different cell lineages. The bones comprising the cranial skeleton are formed through both intramembranous and endochondral ossification, regardless of the origin. The cellular processes involved in the formation of cranial skeletal elements include induction, migration, condensation, differentiation, and proliferation, all of which require sophisticated genetic control. Recent discoveries provide evidence of several signaling pathways and their target genes contributing to cranial skeleton development. The interconnection between individual signaling cascades is extremely complex and creates an entire gene regulatory network. This thesis focuses primarily on genetic programmes controlling the development of neural crest-derived skeletal structures. Keywords: neural crest cells, osteogenesis, chondrogenesis, mesenchymal condensation, gene regulatory network
|
|
|
Genetic variability in sporadic colorectal cancer: Searching for novel risk, prognostic and predictive biomarkers.
Jirásková, Kateřina ; Vodička, Pavel (advisor) ; Machoň, Ondřej (referee) ; Eckschlager, Tomáš (referee)
Colorectal cancer (CRC) is a major public health problem worldwide. Despite improvements in the diagnostic process and advancement in the treatment methods, the prognosis remains poor. To improve survival rates, it is important to identify people with the predisposition for CRC and to detect the potentially curable early stage of the disease. Furthermore, identifying those who would have an adverse clinical outcome associated with a particular chemotherapy would help to avoid redundant chemotherapy burden in patients and contribute to enhanced therapeutic efficacy, while minimizing treatment-related toxicity. The aim of the Thesis was to search for novel promising diagnostic, prognostic and predictive DNA-based biomarkers of sporadic form of CRC. As each patient is genetically unique, these biomarkers would aid clinicians in better diagnosis and/or in the selection of an optimal type of therapy for an individual CRC patient based on their molecular profile. In order to explore this issue, we investigated several candidate genes in healthy individuals as well as in newly diagnosed cancer patients. The major outcomes of this PhD study, which were fully reported in seven publications included in the present Thesis, are 1) The observation of several candidate single nucleotide polymorphisms in microRNA...
|
|
|
The role of Fam208a during mouse embryogenesis
Bhargava, Shohag ; Chawengsaksophak, Kallayanee (advisor) ; Machoň, Ondřej (referee) ; Macůrková, Marie (referee)
(in English) Post-implantation embryo development proceeds through several key morphogenetic events that are fine-tuned by epigenetic modifications. Gastrulation is one of the most crucial developmental event that occurs during early post-implantation stage resulting in the formation of the three germ layers together with the establishment of the anterior-posterior (A-P) axis. It requires a highly coordinated interaction between the embryonic and extra-embryonic regions of the developing embryo. Gastrulation initiates with the formation of the primitive streak and, during which, cells of the epiblast delaminate and ingress through the primitive streak to form the mesoderm and definitive endoderm. During early post-implantation stages, the pluripotent cell population of the epiblast undergoes very rapid cellular proliferation and extensive epigenetic programming. There are numerous studies emphasizing various signaling molecules, transcription factors and epigenetic machinery maintaining the genomic stability that drive successful gastrulation and any discrepancy or defects almost always results in embryonic lethality. One such newly highlighted silencing machinery is that of the Human silencing hub (HUSH) complex comprising of the core members; FAM208A; H3K9me3-reader, MPP8 and PPHLN that together...
|
|
|
Generation and analysis of mutant mouse models to study pathophysiological roles of KLK5 and KLK7 in epidermis
Kašpárek, Petr ; Sedláček, Radislav (advisor) ; Stopka, Pavel (referee) ; Machoň, Ondřej (referee)
Kallikrein-related peptidases (KLKs) constitute a family of closely related serine proteases encoded by genes clustered in one chromosomal locus. KLKs are widely expressed in a variety of tissues and numerous in vitro experiments suggest their important roles in many physiological and pathological processes. However, the biological roles of KLKs in vivo are often obscured mainly due to unavailability of suitable animal models. Although gene deficient mouse models were generated for several KLK genes, they had limited use for understanding the roles of individual proteases in the complex environment in vivo. One of the main obstacles which hampers in vivo analysis is partial functional overlap between some KLKs. This makes traditional single-gene deficient animal models an inadequate tool to address the biological impact of the gene deficiency as compensatory mechanisms often result in a lack of phenotype. In this work, we used the transcription activator-like effector nuclease (TALEN) technology to generate several novel mutant mouse models to study the complex KLK proteolytic pathways and their roles in healthy organism and in disease. We prepared a novel mouse model for Netherton syndrome (NS), an autosomal recessive skin disorder caused by mutation in the gene SPINK5, which encodes the KLK-inhibitor...
|
|
|
Development of new molecular genetic aproaches in assisted reproductive technology
Limbergová, Jana ; Machoň, Ondřej (advisor) ; Šimoník, Ondřej (referee)
Preimplantation genetic testing is one of the major clinical procedures that takes place in centres of assisted reproduction all around the world. It is sought out by couples for many reasons discussed in this paper. The causes of couples' arrival to the centres might vary from inherited diseases that future parents do not wish to transfer to their offspring to the risk of transfer of chromosomal structural rearrangements. What's more, infertility might be caused by the greater risk of aneuploidy in embryos which correlates with higher maternal age and other factors. This paper also focuses on new approaches in cytogenetic examinations for reproductive medicine. Furthermore, it discusses clinical methods used to improve diagnosis and treatment of infertile couples and experimental methods that could become the base of new diagnostic tools. These are for example single nucleotide polymorphism methods, array-based methods, new generation sequencing and whole genome amplifications. It also looks back at methods that became old-fashioned, just like for example fluorescent in situ hybridisation, and states its pros and cons. Key words: preimplantation genetic testing, aneuploidy, structural rearrangements, monogenic diseases, biopsy
|
|
|
Migration and possible skeletogenesis of the trunk neural crest cells in basal fishes
Suchánek, Tomáš ; Černý, Robert (advisor) ; Machoň, Ondřej (referee)
The neural crest is a vertebrate-specific embryonic cell population emerging during neuru- lation in a neuroectoderm. Its cells are highly migratory and differentiate into a wide scale of cell types and tissues ranging from skeletal tissues through pigment cells to neurons and endocrine gland. The neural crest research had been focused on a cranial subpopulation for a long time probably due its apparent skeletogenic activity rather than in the trunk. In this diploma thesis and for a first time I present a data about trunk neural crest cells of basal fishes, Senegal bichir (Polypterus senegalus), sterlet (Acipenser ruthenus) and tropical gar (Atractosteus tropicus). It contains a data about spatio-temporal emergence of trunk neural crest cells of basal fishes, their site of delamination from neuroectoderm, pathways of migration, link between their migration and somite development, segmen- tation during ventro-medial migration and their early diferentiation. Herein I also bring out as first an insight on the trunk neural crest derivatives of the Senegal bichir from in vivo staining experiments using CM-DiI. Key words: trunk neural crest, migratory pathways, exoskeleton, basal ray-finned fishes
|
guest ::
