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Functional role of Islet1 in pancreatic development
Malfatti, Jessica ; Pavlínková, Gabriela (advisor) ; Krausová, Michaela (referee)
1 Abstract Diabetes mellitus is characterized by the dysfunction and reduction of insulin-producing cells, resulting in hyperglycemia, which in long term harms the organism. For future therapy, it is crucial to understand the function of various factors participating in the differentiation and maturation of endocrine pancreatic cells. The aim of this study was to unravel the functional role of ISL1 during the development of the pancreas. ISL1 is expressed in all endocrine cells of the islets of Langerhansbut its function remains unclear, especially during early pancreatogenesis. As the global deletion of this gene is embryonically lethal, we used the tissue specific deletion of Isl1 in Neurod1 possitive cells using the Cre-loxP system. In this work we studied the effect of this deletion on the structure of islets of Langerhans, the formation of endocrine cell types and relative expression of genes during early pancreatic development. A defective achitecture of islets together with postnatal absence of α-cells was found in the Isl1 deletion mutant. Also, the expression of genes important for the specification of α-cell lineage and their subsequent function was decreased. The secondary outcome was the optimalization of a protocol for effective sorting of endocrine cells using fluorescent flow cytometry, which...
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Role of Islet1, BDNF and nanoparticles in development, function and regeneration of the auditory system
Chumak, Tetyana ; Syka, Josef (advisor) ; Druga, Rastislav (referee) ; Maršálek, Petr (referee)
Detailed knowledge of the role that particular genes and factors play during the development and in the normal function of the auditory system is necessary to develop successful regenerative inner ear therapies. Islet1 transcription factor and brain derived neurothrophic factor (BDNF) have great potential to play a role in regenerative inner ear therapy as both have been shown to be sufficient for self-repair regeneration in cochlea in animal studies. In this study we looked at the roles these two factors play in the development and function of the auditory system. In the transgenic mice used in the study, overexpression of Isl1 affected cell specification during embryonic development, leading to enlargement of the cochleovestibular ganglion and accelerated nerve fiber extension and branching in mutant embryos. The hearing of young transgenic mice was not affected. However, it started to decline in 1-month-old animals. This early onset of age-related hearing loss was found to be a consequence of the neurodegeneration of the olivocochlear system caused by Pax2-driven Isl1 misexpression in the hindbrain. Our data provide the first evidence that the alternation of the olivocochlear system efferent system accelerates the age-related functional decline of hearing without the loss of OHCs. The functional role of...
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Development and function of endocrine cells of the pancreas
Hamplová, Adéla ; Pavlínková, Gabriela (advisor) ; Berková, Zuzana (referee)
Diabetes mellitus affects nearly 300 million people in the world. The development of diabetes is caused by dysfunction or by reduction of insulin-producing β-cells that are part of the endocrine pancreas. Therefore, the most critical step for understanding the pathophysiology of diabetes and for restoring lost β cells is the identification of molecular cues that specify the cellular phenotype in the pancreas. This work is based on the hypothesis that the transcription factor NEUROD1 is a key factor for the development of the pancreas and for the maintenance of endocrine tissue function. Neurod1 conditional KO mutants (Neurod1CKO) were generated using the Cre-loxP system by crossing floxed Neurod1 mice with Isl1-Cre line. Immunohistochemical analyses of the pancreas at embryonic day 17.5 and postnatal day 0 showed that the deletion of Neurod1 negatively affected the development, organization of endocrine tissue, and total mass of pancreatic endocrine cells. To better understand molecular changes, quantitative PCR was used to analyse mRNA expression in the developing pancreas at the age of embryonic day 14.5 and postnatal day 1. Genes important for the development and function of the pancreas have been selected for the study of expression changes. These analyses showed changes in expression of genes...
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Development and function of beta-cells
Hamplová, Adéla ; Pavlínková, Gabriela (advisor) ; Tlapáková, Tereza (referee)
Insulin producing β-cells are located in the endocrine pancreas. They are a part of pancreatic islets of Langerhans along with α-, β-, δ-, ε- a PP-cells producing glucagon, somatostatin, ghrelin and pancreatic polypeptide. Insulin regulates glucose uptake into cells and thus contributes to the regulation of energy metabolism. The development of β-cells as well as the development of the pancreas is a complex process. Developmental processes of proliferation, differentiation and total pancreatic organogenesis are best described in the mouse model. The developmental processes and pancreatic functions are regulated by a network of transcription factors. Pancreatic duodenal homeobox gene 1 is a transcription factor that is expressed in the precursors of endocrine, exocrine and ductal cells. Neurogenin 3 is expressed in precursors of the islets of Langerhans cells. Islet 1 regulates the formation of the islets of Langerhans as well as the pair domains of transcription factors 4 and 6, whose expression is later limited only to β-cells. Transcription factors Islet 1 and Neurod 1 regulate insulin production in β-cells. Mutations in transcription factors lead to the abnormal development and altered function of pancreatic cells, including β-cells. Diabetes mellitus is a disease resulting from defects in...
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Role of Islet1, BDNF and nanoparticles in development, function and regeneration of the auditory system
Chumak, Tetyana ; Syka, Josef (advisor) ; Druga, Rastislav (referee) ; Maršálek, Petr (referee)
Detailed knowledge of the role that particular genes and factors play during the development and in the normal function of the auditory system is necessary to develop successful regenerative inner ear therapies. Islet1 transcription factor and brain derived neurothrophic factor (BDNF) have great potential to play a role in regenerative inner ear therapy as both have been shown to be sufficient for self-repair regeneration in cochlea in animal studies. In this study we looked at the roles these two factors play in the development and function of the auditory system. In the transgenic mice used in the study, overexpression of Isl1 affected cell specification during embryonic development, leading to enlargement of the cochleovestibular ganglion and accelerated nerve fiber extension and branching in mutant embryos. The hearing of young transgenic mice was not affected. However, it started to decline in 1-month-old animals. This early onset of age-related hearing loss was found to be a consequence of the neurodegeneration of the olivocochlear system caused by Pax2-driven Isl1 misexpression in the hindbrain. Our data provide the first evidence that the alternation of the olivocochlear system efferent system accelerates the age-related functional decline of hearing without the loss of OHCs. The functional role of...
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