Application of copper isotope abundance measurements to study copper trafficking in vivo
Date
2018-08-20
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Abstract
The determination of the isotopic composition of metals has been increasingly recognized as a powerful tool to monitor metabolism in biological systems. One biologically important metal in living systems is copper, a critical enzyme cofactor, but a potent cellular toxin when unbound inside the cell. This thesis describes the development of an analytical technique to measure isotope amount ratios in biological systems. The technique was then implemented to determine how the distribution of copper isotopes changes in a system where copper metabolism has been impacted in two different ways.
The first application of this technique explored how changing the expression levels of the cellular prion protein (PrPC) could affect the distribution of copper isotopes in the body. Copper isotope amount ratios were measured in the liver, kidney, red blood cells, serum, and different regions of the brain of wild type, PrPC knockout, and mice in which the copper-binding sites were mutated. The liver, kidney and brain tissue samples were enriched in 65Cu compared to the food. Characteristic changes in isotopic distribution were identified between the serum and the liver, the hippocampus, cerebral cortex, and brainstem.
The second application of this technique was a careful examination of the copper isotopic fractionation in the five intestinal regions of mice. The effect of PrPC was investigated and revealed that the copper concentration was lower with inhibition or malfunction of PrPC in all regions of the gut, although only in the large intestine was any genotype dependence on the copper isotopic composition observed. Additionally, the isotopic redistribution of copper in mice with gut bacteria significantly depleted by antibiotic treatment was compared to untreated mice. A significant difference, ~1.0 ‰, in copper isotope abundances were measured in the proximal colon of antibiotic-treated mice. The changes in copper isotopic composition in the gut were associated with changes in copper transporters. Both CTR1, a protein responsible for copper import, and ATP7A, a protein responsible for copper efflux, were significantly down-regulated in antibiotic-treated mice.
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Keywords
Copper isotopes, Isotopic fractionation
Citation
Miller, K. A. (2018). Application of copper isotope abundance measurements to study copper trafficking in vivo (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/32827