IMPACT OF VITAMIN B12 ON C. ELEGANS MODELS OF ALZHEIMER’S DISEASE
| Author(s) | Salsini-Tobias, John | |
| Date Accessioned | 2024-06-25T16:43:57Z | |
| Date Available | 2024-06-25T16:43:57Z | |
| Publication Date | 2023-05 | |
| Abstract | Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by atrophy of neurons in the brain and there are currently an estimated 6.5 million individuals afflicted in the United States. Evidence suggests that build-up of toxic amyloid-beta (Aβ) in the brain is a pathogenic feature of AD. The genetic model organism C. elegans provides a useful system to examine how the modifiable risk factor diet affects Aβ-induced proteotoxicity. Expression of Aβ in C. elegans body-wall muscles causes time-dependent paralysis, allowing for easy determination of factors that impact proteotoxicity. Previously, the Tanis lab has shown that supplementing with the nutrients vitamin B12 and choline protects against Aβ induced paralysis and bioenergetic defects by impacting the methionine/SAM cycle. Phosphatidylcholine (PtdCho) has been observed at reduced levels in individuals with AD and can be synthesized by SAM dependent methylation of phosphoethanolamine or directly from choline through the Kennedy Pathway. To further explore the protective potential of vitamin B12 and choline, I employed a C. elegans strain that expresses Aβ pan-neuronally and exhibits chemotaxis defects in response to the attractant isoamyl alcohol (IA). Attraction to IA was quantified with a chemotaxis index (CI). In this assay, all groups were attracted to the IA treatment, with a significantly lesser attraction observed for Aβ-expressing animals without B12 supplementation. This suggests that Aβ was detrimental to chemotaxis ability and that vitamin B12 supplementation, but not choline supplementation, is protective against Aβ-induced proteotoxicity in this neuronal model. I then developed a protocol for conditioning the animals to IA in the absence of food before performing the assay to determine if the animals could learn that IA is associated with starvation, however, the results were inconsistent. Another area of my thesis work focused on the impact of fatty acid synthesis on Aβ proteotoxicity. Vitamin B12 availability in the diet decreases transcription of the desaturases FAT-5 and FAT-7. To determine if loss of fat-7 affected the protective impact of vitamin B12, I created a strain with a mutation in fat-7 and the body-wall muscle Aβ transgene by genetic recombination. In addition, I used CRISPR-Cas9 to knockout fat-5 in the Aβ animals. We then performed paralysis assays and found that loss of either fat-5 or fat-7 did not impact the vitamin B12 dependent delay in paralysis, indicating that these genes are not required for the protective effect of B12. In conclusion, vitamin B12 has a protective effect in multiple C. elegans models of Aβ-induced proteotoxicity and this is independent of its impact on fatty acid synthesis. | |
| Advisor | enter | |
| Program | enter | |
| URL | https://udspace.udel.edu/handle/19716/34524 | |
| Language | en_US | |
| Publisher | University of Delaware | |
| Title | IMPACT OF VITAMIN B12 ON C. ELEGANS MODELS OF ALZHEIMER’S DISEASE | |
| Type | Thesis |