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Presenilin promotes dietary copper uptake.

Southon A, Greenough MA, Ganio G, Bush AI, Burke R, Camakaris J - PLoS ONE (2013)

Bottom Line: Expression of a copper-responsive EYFP construct was also lower in the midgut of these larvae, indicative of reduced dietary copper uptake.SOD activity was reduced by midgut PSN knockdown, and these flies were sensitive to the superoxide-inducing chemical paraquat.These results are consistent with previous studies of mammalian presenilins, supporting a conserved role for these proteins in mediating copper uptake.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, The University of Melbourne, Victoria, Australia.

ABSTRACT
Dietary copper is essential for multicellular organisms. Copper is redox active and required as a cofactor for enzymes such as the antioxidant Superoxide Dismutase 1 (SOD1). Copper dyshomeostasis has been implicated in Alzheimer's disease. Mutations in the presenilin genes encoding PS1 and PS2 are major causes of early-onset familial Alzheimer's disease. PS1 and PS2 are required for efficient copper uptake in mammalian systems. Here we demonstrate a conserved role for presenilin in dietary copper uptake in the fly Drosophila melanogaster. Ubiquitous RNA interference-mediated knockdown of the single Drosophila presenilin (PSN) gene is lethal. However, PSN knockdown in the midgut produces viable flies. These flies have reduced copper levels and are more tolerant to excess dietary copper. Expression of a copper-responsive EYFP construct was also lower in the midgut of these larvae, indicative of reduced dietary copper uptake. SOD activity was reduced by midgut PSN knockdown, and these flies were sensitive to the superoxide-inducing chemical paraquat. These data support presenilin being needed for dietary copper uptake in the gut and so impacting on SOD activity and tolerance to oxidative stress. These results are consistent with previous studies of mammalian presenilins, supporting a conserved role for these proteins in mediating copper uptake.

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Related in: MedlinePlus

Copper tolerance in Drosophila overexpressing DmATP7.MEX-GAL4 was used to knockdown PSN in the midgut together with overexpression of the copper transporter DmATP7. Flies were allowed to lay eggs on basal media and copper-supplemented media and the genotype of the surviving offspring was determined: control (MEX-GAL4/Cyo; +/TM6b), PSN RNAi (MEX-GAL4/PSN RNAi; TM6b/+), DmATP7 overexpression (MEX-GAL4/Cyo; pUAST-DmATP7/TM6b), PSN knockdown and DmATP7 overexpression (MEX-GAL4/PSN RNAi; pUAST-DmATP7/TM6b). Emergence of each genotype was expressed as a proportion of the total number of adults that emerged on each media. Flies overexpressing DmATP7 did not survive on 2 mM copper, but this copper-sensitivity was overcome by simultaneous knockdown of PSN.
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pone-0062811-g002: Copper tolerance in Drosophila overexpressing DmATP7.MEX-GAL4 was used to knockdown PSN in the midgut together with overexpression of the copper transporter DmATP7. Flies were allowed to lay eggs on basal media and copper-supplemented media and the genotype of the surviving offspring was determined: control (MEX-GAL4/Cyo; +/TM6b), PSN RNAi (MEX-GAL4/PSN RNAi; TM6b/+), DmATP7 overexpression (MEX-GAL4/Cyo; pUAST-DmATP7/TM6b), PSN knockdown and DmATP7 overexpression (MEX-GAL4/PSN RNAi; pUAST-DmATP7/TM6b). Emergence of each genotype was expressed as a proportion of the total number of adults that emerged on each media. Flies overexpressing DmATP7 did not survive on 2 mM copper, but this copper-sensitivity was overcome by simultaneous knockdown of PSN.

Mentions: We next sought to determine whether PSN knockdown could overcome the copper sensitivity caused by overexpression of DmATP7 in the midgut. A compound heterozygous strain (PSN-RNAi/Cyo; pUAST-DmATP7/TM6b) was crossed with the homozygous MEX-GAL4 driver strain and allowed to lay eggs on basal media and media supplemented with additional copper (Figure 2). The emergence of each of the four genotypes was expressed as a proportion of the total number of adults that emerged on each media. Flies overexpressing DmATP7 did not survive on 2 mM copper, but this copper-sensitivity was overcome by simultaneous knockdown of PSN. This is consistent with PSN knockdown affecting midgut copper homeostasis prior to copper export across the basolateral membrane into the circulation.


Presenilin promotes dietary copper uptake.

Southon A, Greenough MA, Ganio G, Bush AI, Burke R, Camakaris J - PLoS ONE (2013)

Copper tolerance in Drosophila overexpressing DmATP7.MEX-GAL4 was used to knockdown PSN in the midgut together with overexpression of the copper transporter DmATP7. Flies were allowed to lay eggs on basal media and copper-supplemented media and the genotype of the surviving offspring was determined: control (MEX-GAL4/Cyo; +/TM6b), PSN RNAi (MEX-GAL4/PSN RNAi; TM6b/+), DmATP7 overexpression (MEX-GAL4/Cyo; pUAST-DmATP7/TM6b), PSN knockdown and DmATP7 overexpression (MEX-GAL4/PSN RNAi; pUAST-DmATP7/TM6b). Emergence of each genotype was expressed as a proportion of the total number of adults that emerged on each media. Flies overexpressing DmATP7 did not survive on 2 mM copper, but this copper-sensitivity was overcome by simultaneous knockdown of PSN.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646984&req=5

pone-0062811-g002: Copper tolerance in Drosophila overexpressing DmATP7.MEX-GAL4 was used to knockdown PSN in the midgut together with overexpression of the copper transporter DmATP7. Flies were allowed to lay eggs on basal media and copper-supplemented media and the genotype of the surviving offspring was determined: control (MEX-GAL4/Cyo; +/TM6b), PSN RNAi (MEX-GAL4/PSN RNAi; TM6b/+), DmATP7 overexpression (MEX-GAL4/Cyo; pUAST-DmATP7/TM6b), PSN knockdown and DmATP7 overexpression (MEX-GAL4/PSN RNAi; pUAST-DmATP7/TM6b). Emergence of each genotype was expressed as a proportion of the total number of adults that emerged on each media. Flies overexpressing DmATP7 did not survive on 2 mM copper, but this copper-sensitivity was overcome by simultaneous knockdown of PSN.
Mentions: We next sought to determine whether PSN knockdown could overcome the copper sensitivity caused by overexpression of DmATP7 in the midgut. A compound heterozygous strain (PSN-RNAi/Cyo; pUAST-DmATP7/TM6b) was crossed with the homozygous MEX-GAL4 driver strain and allowed to lay eggs on basal media and media supplemented with additional copper (Figure 2). The emergence of each of the four genotypes was expressed as a proportion of the total number of adults that emerged on each media. Flies overexpressing DmATP7 did not survive on 2 mM copper, but this copper-sensitivity was overcome by simultaneous knockdown of PSN. This is consistent with PSN knockdown affecting midgut copper homeostasis prior to copper export across the basolateral membrane into the circulation.

Bottom Line: Expression of a copper-responsive EYFP construct was also lower in the midgut of these larvae, indicative of reduced dietary copper uptake.SOD activity was reduced by midgut PSN knockdown, and these flies were sensitive to the superoxide-inducing chemical paraquat.These results are consistent with previous studies of mammalian presenilins, supporting a conserved role for these proteins in mediating copper uptake.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, The University of Melbourne, Victoria, Australia.

ABSTRACT
Dietary copper is essential for multicellular organisms. Copper is redox active and required as a cofactor for enzymes such as the antioxidant Superoxide Dismutase 1 (SOD1). Copper dyshomeostasis has been implicated in Alzheimer's disease. Mutations in the presenilin genes encoding PS1 and PS2 are major causes of early-onset familial Alzheimer's disease. PS1 and PS2 are required for efficient copper uptake in mammalian systems. Here we demonstrate a conserved role for presenilin in dietary copper uptake in the fly Drosophila melanogaster. Ubiquitous RNA interference-mediated knockdown of the single Drosophila presenilin (PSN) gene is lethal. However, PSN knockdown in the midgut produces viable flies. These flies have reduced copper levels and are more tolerant to excess dietary copper. Expression of a copper-responsive EYFP construct was also lower in the midgut of these larvae, indicative of reduced dietary copper uptake. SOD activity was reduced by midgut PSN knockdown, and these flies were sensitive to the superoxide-inducing chemical paraquat. These data support presenilin being needed for dietary copper uptake in the gut and so impacting on SOD activity and tolerance to oxidative stress. These results are consistent with previous studies of mammalian presenilins, supporting a conserved role for these proteins in mediating copper uptake.

Show MeSH
Related in: MedlinePlus