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Presenilin promotes dietary copper uptake.

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.

SUBMITTER: Southon A

PROVIDER: S-EPMC3646984 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background:The objective of this study was to determine the effects of supplementing Cu on growth performance, Cu metabolism and Cu-related enzyme activities of weanling pigs fed diets with two different Cu sources, and to estimate optimal Cu requirements and relative bioavailability from these two sources for pigs. Methods:Weanling pigs were allocated to 14 treatments arranged factorially, including 6 added Cu levels (5, 10, 20, 40, 80, 160?mg/kg), and 2 mineral sources (tribasic Cu chloride, TBCC and copper proteinate, CuPro), as well as one negative control (0?mg/kg added Cu level) and one maximum allowed level treatment (200?mg/kg TBCC) for the entire 38-d experiment. Growth performance, mineral status and enzyme activities were measured at the end of this study. Results:Increasing levels of Cu showed linear and quadratic responses (P?< 0.01) for final BW, ADG and FCR regardless of the sources. Supplementation with TBCC (>?80?mg/kg) and CuPro (>?20?mg/kg) significantly decreased (P?< 0.05) diarrhea incidence of weanling pigs. There were linear and quadratic increases (P?< 0.01) in bile, hepatic, and intestinal Cu concentrations, fecal Cu contents, and plasma enzyme activities (alkaline phosphatase, ceruloplasmin, Cu, Zn-Superoxide dismutase (Cu/Zn SOD), and glutathione peroxidase), whereas plasma malondialdehyde decreased (P?< 0.01) linearly and quadratically as dietary Cu level increased. Similarly, pigs fed CuPro absorbed and retained more Cu and excreted less Cu than those fed TBCC when supplemented 80?mg/kg and above. Optimal dietary Cu requirements for pigs from 28 to 66 d of age estimated based on fitted broken-line models (P?< 0.05) of bile Cu, plasma Cu/Zn SOD and growth performance were 93-140?mg/kg from TBCC, and 63-98?mg/kg from CuPro accordingly. According to slope ratios from multiple linear regression, the bioavailability value of CuPro relative to TBCC (100%) was 156-263% (P?< 0.01). Conclusion:The findings indicated that Cu recommendation from current NRC (5-6?mg/kg) was not sufficient to meet the high requirement of weanling pigs. Cu from CuPro was significantly more bioavailable to weanling pigs than TBCC in stimulating growth and enzyme activities, decreasing diarrhea frequency and fecal Cu contents to the environment.

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Presenilin promotes dietary copper uptake.

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