| Summary: | Thesis advisor: Thomas N. Seyfried === Gangliosides are glycosphingolipids (GSLs) containing sialic acids that play numerous roles in neuronal maturation, apoptotic signaling, angiogenesis, and cell surface receptor activity. The GM1 and GM2 gangliosidoses are a series of autosomal recessive lysosomal storage disorders (LSDs) characterized by an inability to degrade these lipid molecules. GM1 gangliosidosis is caused by a mutation in the lysosomal hydrolase β-galactosidase, resulting in neuronal storage of ganglioside GM1 and asialo GA1. Tay-Sachs (TS) and Sandhoff Disease (SD) are GM2 gangliosidoses caused by mutations in either the α or β subunits, respectively, of the heterodimeric protein β- hexosaminidase A, resulting in the storage of ganglioside GM2 and asialo GA2. The accumulation of excess ganglioside in the central nervous system leads to abnormal intracellular vacuoles, neuronal loss, demyelination, ataxia, dementia, and premature death. In my studies, I have shown that accumulation of GM1 ganglioside may not coincide with secondary storage of cholesterol, by providing evidence that cholesterol-binding fluorescent molecule filipin reacted to GM1 ganglioside in the absence of cholesterol. In an effort to combat the early-onset gangliosidoses, I have explored the effects of combining Neural Stem Cells (NSCs) with Substrate Reduction Therapy (SRT) in juvenile Sandhoff mice. The analysis showed that SRT was more effective than NSCs in reducing stored GM2 and GA2 in young mice, and no synergy was observed. In adult GM1 gangliosidosis, Tay- Sachs, and Sandhoff mice, Adeno-Associated Viral (AAV) vector gene therapy was used to restore therapeutic levels of wild-type enzyme to the CNS. AAV therapy corrected ganglioside storage and ameliorated myelin-associated lipid loss in all tissues assayed, increasing motor performance and life in effected animals. Lastly, AAV therapy was also successful in a feline model of Sandhoff disease. These results in juvenile and adult model systems point the way towards multiple effective clinical therapies in the near future. === Thesis (PhD) — Boston College, 2011. === Submitted to: Boston College. Graduate School of Arts and Sciences. === Discipline: Biology.
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