Quan Zhong, Ph.D. (Advisor); Lynn Hartzler, Ph.D. (Committee Member); Paula Ann Bubulya, Ph.D. (Committee Member)
Master of Science (MS)
The presynaptic protein alpha-synuclein encoded by SNCA is the primary component of Lewy bodies and Lewy neurites which are the histopathological hallmarks of Parkinson’s disease. While the etiology of Parkinson’s remains unclear, SNCA mutations and copy number variations are one of several genes linked to Parkinson’s. The family of highly conserved chaperone proteins 14-3-3 have been shown to co-aggregate and share regions of 40% homology with alpha-synuclein. Mitochondrial dysfunction also plays a role in Parkinson’s disease with abnormalities in mitochondrial respiration due to interference of complex I in the electron transport chain being found in Parkinson’s patients. Alpha-synuclein increases fragmentation of mitochondria and accumulation of reactive oxygen species due to mitochondrial dysfunction which causes toxic oligomers of alpha-synuclein to form. In yeast, the molecular mechanisms of neurodegenerative disorders can be recapitulated because of the high conservation of cellular processes between eukaryotes and yeast. These mechanisms include the cytotoxic effects of human alpha-synuclein and its aggregate formation, as well as recapitulating the toxic phenotypes observed in human and transgenic animal models, allowing for genetic screenings for modifiers of alpha-synuclein. The drawback of prior yeast screenings is the restriction of the galactose induced GAL1 promoter. Our laboratory previously found a mutant gal3 allele that induces the GAL1 promoter for utilization under non-galactose conditions. I assessed the growth phenotype of an IntTox yeast strain with genome integrated 4-5 copies of the SNCA gene under the control of the GAL1 promoter by inducing SNCA expression under respiratory growth conditions using glycerol and ethanol as the carbon source. I demonstrated that the integrated IntTox SNCA strain recapitulated alpha-synuclein cytotoxicity under galactose and glycerol ethanol conditions allowing for comparative analysis of mitochondria dependent and independent conditions. When grown on glycerol ethanol, four 14-3-3 isoforms mildly suppressed alpha-synuclein cytotoxicity while the same four isoforms enhanced cytotoxicity under galactose conditions. These changes in toxicity may be independent of the presence of inclusion bodies. These results demonstrate the 14-3-3 isoforms behave differently under mitochondria dependent conditions. Our future research will identify whether the suppressive effects of these 14-3-3 isoforms on alpha-synuclein cytotoxicity are due to mitochondrial morphology or membrane potential changes.
Department or Program
Department of Biological Sciences
Year Degree Awarded
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