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Showing 1 to 4 of 4 (0.072 seconds)Spelling suggestions: "subject:"high osmolality glycerol""
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The Characterization of Genes Involved in Response to the Phenol Derivative and Xenoestrogen Bisphenol-A in Saccharomyces CerevisiaeFarina, Sasha N 01 January 2011 (has links)
Bisphenol A is an estrogenic compound that is found in polycarbonate plastics and epoxy resins; humans are continuously exposed to the compound and it is believed to possess the same carcinogenic effects as estrogen (Iso, 2006). In this study, I used Saccharomyces cerevisiae as a model organism to identify mechanisms by which BPA acts based on the genomic profiling of kinase genes from a Mat-α haploid deletion library. Kinases regulate many other proteins, so the identification of a single mutant could identify an entire affected pathway of genes. I conducted a systematic screen of these mutants using the phenotype of growth inhibition. Using solid growth assays, I identified 17 BPA sensitive mutants, six of which were related to the high osmolarity growth pathway, which is involved in osmotic stress response and could be a mechanism of defense of S. cerevisiae against BPA. I implemented liquid growth assays, protein analysis, as well as microscopy for a more in depth study of the effects of BPA on these mutants. Bisphenol-A initially inhibits the growth of S. cerevisiae, however, there were some strains that appeared to show adaptation in the presence of the compound. I found that BPA inhibits cell cycle progression, and may affect the phosphorylation regulation of Cdc28, but without affecting the production of the protein. This study provides clues for predicting the effects of BPA on homologous genes in mammals and identifying similar pathways of resistance. By having a better understanding of the effects on BPA on the cell, the compound can be better regulated by the EPA and complications resulting from continuous exposure to BPA can be treated effectively.
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Signaling specificity in the filamentous growth pathway of Saccharomyces cerevisiaeRomelfanger, Claire Theresa, 1982- 03 1900 (has links)
xii, 41 p. : ill. / Cells convey information through signaling pathways. Distinct signaling pathways often rely on similar mechanisms and may even use the same molecules. With a variety of signals conveyed by pathways that share components, how does the cell maintain the integrity of each pathway?
Budding yeast provides an example of multiple signaling pathways utilizing the same components to transduce different signals. The mating pathway, the high osmolarity glycerol (HOG) pathway and the filamentous growth (FG) pathway each respond to different environmental conditions and generate unique cellular responses. Despite the individuality of the pathways, they each contain a core group of the same signaling proteins. How does the cell generate a variety or responses utilizing the same group of proteins? Both the mating and HOG pathways utilize scaffolding factors that concentrate pathway components to the location of activation and in the case of the mating pathway alter the kinetics of the interaction. In addition, negative regulatory mechanisms operate in both the mating and HOG pathways. These negative regulatory mechanisms are understood in detail for the mating pathway but not for the HOG pathway. Mechanisms for providing specificity for the FG pathway are as yet unknown.
The purpose of this work is to elucidate the mechanisms that provide specificity to the FG pathway. The search for specificity factors was done through both a random mutagenesis screen and a synthetic genetic array screen, looking for mutants in which activation of the FG pathway led to inappropriate activation of the HOG pathway. The random mutagenesis screen resulted in a large number of mutants that I organized into five complementation groups. The identity of the gene mutated in the largest complementation group was sought using a variety of methods including complementation with the yeast deletion collection and whole genome sequencing. A synthetic genetic array was screened as an alternative method to identify genes necessary for FG pathway specificity. These experiments have resulted in a list of candidate genes, but thus far have not yet led to any discernable mechanism for maintenance of FG pathway specificity. / Committee in charge: Karen Guillemin, Chairperson;
George F. Sprague Jr., Advisor;
Tom Stevens, Member;
Tory Herman, Member;
Diane Hawley, Outside Member
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The Rtg1 and Rtg3 proteins are novel transcription factors regulated by the yeast hog1 mapk upon osmotic stressNoriega Esteban, Núria 27 February 2009 (has links)
La adaptación de la levadura Saccharomyces cerevisiae a condiciones de alta osmolaridad está mediada por la vía de HOG ((high-osmolarity glycerol). La activación de esta vía induce una serie de respuestas que van a permitir la supervivencia celular en respuesta a estrés. La regulación génica constituye una respuesta clave para dicha supervivencia. Se han descrito cinco factores de transcripción regulados por Hog1 en respuesta a estrés osmótico. Sin embargo, éstos no pueden explicar la totalidad de los genes regulados por la MAPK Hog1. En el presente trabajo describimos cómo el complejo transcripcional formado por las proteínas Rtg1 y Rtg3 regula, a través de la quinasa Hog1, la expresión de un conjunto específico de genes. Hog1 fosforila Rtg1 y Rtg3, aunque ninguna de estas fosforilaciones son esenciales para regulación transcripcional en respuesta a estrés. Este trabajo también muestra cómo la deleción de proteínas RTG provoca osmosensibilidad celular, lo que indica que la integridad de la vía de RTG es esencial para la supervivencia celular frente a un estrés osmótico. / In Saccharomyces cerevisiae the adaptation to high osmolarity is mediated by the HOG (high-osmolarity glycerol) pathway, which elicits different cellular responses required for cell survival upon osmostress. Regulation of gene expression is a major adaptative response required for cell survival in response to osmotic stress. At least five transcription factors have been reported to be controlled by the Hog1 MAPK. However, they cannot account for the regulation of all of the genes under the control of the Hog1 MAPK. Here we show that the Rtg1/3 transcriptional complex regulates the expression of specific genes upon osmostress in a Hog1-dependent manner. Hog1 phosphorylates both Rtg1 and Rtg3 proteins. However, none of these phosphorylations are essential for the transcriptional regulation upon osmostress. Here we also show that the deletion of RTG proteins leads to osmosensitivity at high osmolarity, suggesting that the RTG-pathway integrity is essential for cell survival upon stress.
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SCF cdc4 regulates msn2 and msn4 dependent gene expression to counteract hog1 induced lethalityVendrell Arasa, Alexandre 16 January 2009 (has links)
L'activació sostinguda de Hog1 porta a una inhibició del creixement cel·lular. En aquest treball, hem observat que el fenotip de letalitat causat per l'activació sostinguda de Hog1 és parcialment inhibida per la mutació del complexe SCFCDC4. La inhibició de la mort causada per l'activació sostinguda de Hog1 depèn de la via d'extensió de la vida. Quan Hog1 s'activa de manera sostinguda, la mutació al complexe SCFCDC4 fa que augmenti l'expressió gènica depenent de Msn2 i Msn4 que condueix a una sobreexpressió del gen PNC1 i a una hiperactivació de la deacetilassa Sir2. La hiperactivació de Sir2 és capaç d'inhibir la mort causada per l'activació sostinguda de Hog1. També hem observat que la mort cel·lular causada per l'activació sostinguda de Hog1 és deguda a una inducció d'apoptosi. L'apoptosi induïda per Hog1 és inhibida per la mutació al complexe SCFCDC4. Per tant, la via d'extensió de la vida és capaç de prevenir l'apoptosi a través d'un mecanisme desconegut. / Sustained Hog1 activation leads to an inhibition of cell growth. In this work, we have observed that the lethal phenotype caused by sustained Hog1 activation is prevented by SCFCDC4 mutants. The prevention of Hog1-induced cell death by SCFCDC4 mutation depends on the lifespan extension pathway. Upon sustained Hog1 activation, SCFCDC4 mutation increases Msn2 and Msn4 dependent gene expression that leads to a PNC1 overexpression and a Sir2 deacetylase hyperactivation. Then, hyperactivation of Sir2 is able to prevent cell death caused by sustained Hog1 activation. We have also observed that cell death upon sustained Hog1 activation is due to an induction of apoptosis. The apoptosis induced by Hog1 is decreased by SCFCDC4 mutation. Therefore, lifespan extension pathway is able to prevent apoptosis by an unknown mechanism.
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