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Dissertation
Investigating Na⁺ and lipid homeostasis as targets for antimalarial drugs
Doctor of Philosophy (Ph.D.), Drexel University
Apr 2018
DOI:
https://doi.org/10.17918/D83X0N
Abstract
In an effort to combat the emerging resistance towards front line anti-malarials, novel therapeutics have been discovered that target the parasite's Na⁺ homeostasis. Studies with the pyrazoleamides and spiroindolones indicate that a disruption to the Na⁺ homeostasis leads to a consequent loss in regulation of cholesterol levels within the parasite plasma membrane. Additional compounds were identified that disrupted cholesterol homeostasis independent of Na⁺ homeostasis disruption. A medium throughput assay was established to screen for compounds acting on the cholesterol homeostasis pathway. Screening of 800 open source compounds identified several hits that disrupted cholesterol homeostasis in Plasmodium falciparum. Investigations in P. falciparum using a Na⁺ ionophore with potent anti-parasitic activity established a linkage between Na⁺ levels and cholesterol homeostasis disruption. We showed that the resistance of mammalian cells towards this ionophore treatment stems from their capacity to suppress disruption to their ion gradients while parasites appear to possess no such compensatory mechanism, ultimately leading to their demise. Resistance towards the pyrazoleamide PA21A092 was attributed to mutations in 2 genes: PfATP4 and a putative zinc-finger protein. Using CRISPR/Cas9 we introduced the PfATP4 A211V mutation and observed that the mutant allele of PfATP4 was sole contributor to resistance towards PA21A092. On further investigation into the hypersensitivity of PA21A092 resistant parasites towards spiroindolones, we observed that resistant parasites were subjected to overall higher rates of Na⁺ influx upon treatment with the spiroindolone KAE609 when compared to wild-type counterparts. We were also able to show that PfATP4 mutants have no discernable alteration to their Na⁺ efflux efficiency, although parasites expressing the A211V mutant of PfATP4 showed a significant fitness defect.
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Details
- Title
- Investigating Na⁺ and lipid homeostasis as targets for antimalarial drugs
- Creators
- Suyash Bhatnagar - DU
- Contributors
- Akhil B. Vaidya (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- XIII, 157 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; College of Medicine; Drexel University
- Other Identifier
- 7960; 991014632291504721