Tay-Sachs disease and its related disorders (GM2 gangliosidoses) are neurodegenerative diseases caused by the excessive accumulation of ganglioside GM2, an otherwise non-toxic plasma membrane component, in the lysosomes of cells of the central nervous system. The accumulation of ganglioside GM2 is the result of a defect in the gene encoding the α-subunit of β-hexosaminidase A (Hex A), an acid hydrolase responsible for the metabolism of gangloside GM2 in the lysosome. Though a debilitating disease in humans, Tay-Sachs model mice (𝘏𝘦𝘹𝘢-/-) escape symptoms by the action of lysosomal sialidase, which is expressed in mice at levels sufficient to metabolize ganglioside GM2 and effectively "bypass" Hex A deficiency. In an attempt to understand why a lysosomal sialidase-mediated bypass of Hex A deficiency is not observed in humans, we cloned ~ 2.9 kb of the human lysosomal sialdiase promoter and began characterization of the regulatory machinery that determines its activity. The transcription factor CDP (CCAAT -Displacement Protein) and truncations thereof were found to have a clear and consistent effect on promoter activity 𝘪𝘯 𝘷𝘪𝘵𝘳𝘰, with the truncation CDP⁸³¹⁻¹⁵⁰⁵ resulting in a near 50-fold increase in activity. Adenovirus-mediated gene transfer of CDP⁸³¹⁻¹⁵⁰⁵ into CRB/TSD cells, a human Tay-Sachs neuroglia cell line, resulted in elevated lysosomal sialidase activity and a decrease in ganglioside GM2 stores. These results suggest that the regulatory machinery responsible for lysosomal sialidase expression may be manipulated in such a way as to "activate" a sialidase-mediated bypass of Hex A deficiency in human Tay-Sachs cells. Thus, induction of lysosomal sialidase may have a potential therapeutic benefit in human Tay-Sachs disease and other Hex A-deficient GM2 gangliosidoses. / Thesis / Master of Science (MS)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22984 |
| Date | 12 1900 |
| Creators | Johnson, Matthew |
| Contributors | Igdoura, Suleiman, Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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