| dc.contributor.author | Flaman, Anathea S. | en_US |
| dc.date.accessioned | 2014-10-21T12:36:06Z | |
| dc.date.available | 2005 | |
| dc.date.issued | 2005 | en_US |
| dc.identifier.other | AAINR08411 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/54742 | |
| dc.description | Niemann-Pick Type C (NPC) disease is a fatal neurodegenerative disorder characterized by endosomal and lysosomal lipid accumulation. Most cases of NPC disease result from mutations in the NPC1 gene. To investigate NPC1 function, the single NPC1-related gene, NCR1 in the yeast Saccharomyces cerevisiae was deleted or overexpressed. Loss of NCR1 did not influence cell proliferation, lipid metabolism, protein secretion, or cell response to chemical agents, suggesting Ncr1 is not required or other proteins can compensate for NCR1 deficiency under the conditions examined. | en_US |
| dc.description | Overexpression of NCR1 was found to be deleterious. All nonessential yeast gene deletion mutants that rendered cells hypersensitive or resistant to NCR1 overexpression toxicity were identified by synthetic genetic array screens. Cell polarity genes were found to contribute to survival when NCR1 was overexpressed, implying a role for NCR1 in recycling materials from sites of polarized growth. Deletion of several genes encoding transporters alleviated NCR1-overexpression toxicity while loss of the NHX1-encoded sodium-proton antiporter enhanced NCR1 overexpression toxicity. These genetic interactions imply Ncr1 may participate in an opposing process or negatively regulate Nhx1 activity. Yeast lacking NHX1 (nhx1Delta) display defects in retrograde vesicular trafficking from the late endosomal prevacuolar compartment (PVC). In contrast, NCR1 overexpression did not impair delivery of carboxypeptidase Y to the vacuole, the yeast hydrolytic compartment, suggesting Ncr1 does not negatively regulate Nhx1 or mediate Golgi-to-PVC trafficking. However, like deletion of NHX1, NCR1 overexpression increased sensitivity to a small, positively charged aminoglycoside antibiotic, hygromycin B, a phenotype associated with hyperpolarization of the plasma membrane or defective vacuolar sequestration of the drug. Deletion of NCR1 increased resistance to hygromycin B, suggesting Ncr1 might regulate cation or proton uptake or efflux from the PVC. A role for Ncr1 in intracellular ion homeostasis was further implied by finding NCR1 was essential when cells lacking the vacuolar H+-ATPase, a major contributor to pH homeostasis, were grown on media buffered to extremes in pH. If the human NPC1 protein participates in regulating the pH of intracellular compartments, as suggested by the findings with the yeast Ncr1 protein, defective pH homeostasis may be the primary cellular defect in NPC disease. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 2005. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Molecular. | en_US |
| dc.title | Genetic approaches to characterize the role of the yeast Niemann-Pick C-related gene, NCR1. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
