Browsing by Subject "Minisatellite"
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Item Identification and characterization of novel factors that influence minisatellite stability in stationary phase yeast cells(2012-11) Alver, Bonnie MaureenThe eukaryotic genome is primarily comprised of non-coding regions of DNA consisting of several different types of repetitive elements. Minisatellites are a type of tandem repetitive element and are composed of repeat units that are 15-100bp in length. Rare altered alleles of minisatellites are associated with an increased risk of several different types of disease including cancer, diabetes, epilepsy and coronary artery disease. However, little is known about what factors prevent minisatellites from alternating and becoming potential pathogenic alleles. Our lab previously developed a color segregation assay to detect minisatellite instability in the yeast saccharomyces cerevisiae. Using this assay, we discovered a unique color segregation phenotype known as `blebbing' which was shown to be indicative of minisatellite alterations that occurred in stationary phase yeast cells. Here, we perform a genome-wide screen known as the Synthetic Genetic Array (SGA) analysis to screen for mutants strains bearing different types of minisatellite alleles that produced a strong blebbing phenotype. Through our work, we identify over 100 candidate genes that regulate the stability of a minisatellite in stationary phase. Further characterization of specific subsets of these genes demonstrates that minisatellites are regulated by different factors depending upon the repeat unit composition and size. We also demonstrate the checkpoint and mismatch repair components are important for stationary phase minisatellite stability and that alterations occurring in mutant strains are mediated by mechanisms utilizing recombination. Together our work provides novel insight into the factors governing minisatellite stability in a unique population of non-dividing cells.Item Identification and characterization of novel factors that influence minisatellite stability in stationary phase yeast cells(2012-11) Alver, Bonnie MaureenThe eukaryotic genome is primarily comprised of non-coding regions of DNA consisting of several different types of repetitive elements. Minisatellites are a type of tandem repetitive element and are composed of repeat units that are 15-100bp in length. Rare altered alleles of minisatellites are associated with an increased risk of several different types of disease including cancer, diabetes, epilepsy and coronary artery disease. However, little is known about what factors prevent minisatellites from alternating and becoming potential pathogenic alleles. Our lab previously developed a color segregation assay to detect minisatellite instability in the yeast Saccharomyces cerevisiae. Using this assay, we discovered a unique color segregation phenotype known as `blebbing' which was shown to be indicative of minisatellite alterations that occurred in stationary phase yeast cells. Here, we perform a genome-wide screen known as the Synthetic Genetic Array (SGA) analysis to screen for mutants strains bearing different types of minisatellite alleles that produced a strong blebbing phenotype. Through our work, we identify over 100 candidate genes that regulate the stability of a minisatellite in stationary phase. Further characterization of specific subsets of these genes demonstrates that minisatellites are regulated by different factors depending upon the repeat unit composition and size. We also demonstrate the checkpoint and mismatch repair components are important for stationary phase minisatellite stability and that alterations occurring in mutant strains are mediated by mechanisms utilizing recombination. Together our work provides novel insight into the factors governing minisatellite stability in a unique population of non-dividing cells.Item Minisatellites in meiosis: crossover regulation and stability of repetitive DNA.(2012-04) LeClere, Andrea RuthThe minisatellite associated with the human HRAS1 proto-oncogene has an enhancer effect on HRAS1 expression. Rare minisatellite alleles have stronger enhancer activity and are frequently found in primary tumors of cancer patients. Rare alleles derive from a common allele that has undergone an alteration in length; alterations occur primarily during the process of meiotic recombination. Identifying factors that regulate minisatellite stability during meiosis is important to our understanding of the initiation and predisposition of minisatellite-associated human diseases. This is the focus of the Kirkpatrick lab using a minisatellite model system in yeast Saccharomyces cerevisiae where an HRAS1 minisatellite allele has been inserted into the promoter region upstream of the HIS4 locus on chromosome III. In this study, we identified CSM3, TOF1, and MRC1 as factors that contribute to meiotic minisatellite alterations. We also uncovered a novel recombination phenotype associated with the HRAS1 minisatellite in MSH4 and MSH5 mutants. Both of these projects have broader implications on our understanding of factors that regulate minisatellite alterations during meiosis. We present models based on our data and previously published research to explain the observed phenotypes.