A New Model of Amyotrophic Lateral Sclerosis in Drosophila melanogaster: Precise Genetic Engineering, Characterization and Genetic Suppression

Sahin, Asli

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Year:: 2015
Contributor:: Sahin, Asli (creator); Reenan, Robert (Director); Fallon, Justin (Reader); Hart, Anne (Reader); Wharton, Kristi (Reader); Bonini, Nancy (Reader); Brown University. BIOMED: Molecular Biology, Cell Biology, and Biochemistry (sponsor)
Genre:: theses
Subject:: ALS; Motor neuron; Disease; neurodegeneration; homologous recombination; ems; genetic screen; Drosophila; Genetic engineering
Extent:: xvii, 342 p.
DOI: https://doi.org/10.7301/Z0MG7MXP

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Abstract:: ABSTRACT Amyotrophic Lateral Sclerosis (ALS), the most common adult-onset motor neuron disease in the world, can be caused by mutations scattered along the full length of the Copper-Zinc Superoxide Dismutase 1 (SOD1) gene. Although ALS was characterized two decades ago as progressive muscle weakness due to extensive loss of motor neurons, the mechanisms underlying this incurable disease still remain elusive. More than 150 different point mutations have been found in the 153 amino acid encoding SOD1 gene of ALS patients. Despite substantial investigations in current SOD1-ALS animal models and post-mortem tissue analyses, the cellular mechanisms by which mutant SOD1 protein acquires toxic function are not well understood. One of the strongest hypotheses in the field suggests that aggregation due to misfolded SOD1 mediates cellular cytotoxicity. On the other hand, oxidative stress seems to play a critical role in ALS pathogenesis, since some transgenic models, especially those with low transgene copy number, do not develop disease symptoms unless they are challenged by reactive oxygen species. To address concerns about the dosage of mutant SOD1 in disease pathogenesis, we have genetically engineered four human ALS-causing SOD1 point mutations (G37R, H48R, H71Y and G85R) into the endogenous locus of Drosophila SOD1 (dSod1) via ends-out homologous recombination (HR); and analyzed the molecular, biochemical and behavioral alterations that arise from these mutations. Contrary to previous transgenic models, we have recapitulated ALS-like phenotypes in the fast ALS progression-causing SOD1 mutants without overexpressing the mutant protein. Drosophila carrying mutations causing fast disease progression in ALS patients (G85R and H71Y) exhibited neurodegeneration, locomotion deficit, and shortened life span whereas Drosophila carrying mutations causing slow disease progression in ALS patients (G37R and H48R) were indistinguishable when compared to controls. Next, we expanded characterization of ALS-like phenotype in Drosophila by performing a detailed expression profile from dSod1 mutants using deep sequencing technologies. Lastly, we performed a large-scale genetic screen aiming to identify suppressors to reverse lethality resulting from severe ALS mutations in Drosophila. This thesis work demonstrates a major step forward in our understanding of the molecular mechanisms and suppressors of mutant SOD1 when a precisely controlled system is studied.
Notes:: Thesis (Ph.D. -- Brown University (2015)

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Sahin, Asli, "A New Model of Amyotrophic Lateral Sclerosis in Drosophila melanogaster: Precise Genetic Engineering, Characterization and Genetic Suppression" (2015). Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z0MG7MXP

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Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations

Theses and Dissertations for the Molecular Biology, Cell Biology, and Biochemistry department.
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