Presenilin promotes dietary copper uptake

Area of Science:

• Cell Biology
• Genetics
• Neuroscience

Background:

• Dietary copper is essential for cellular function, acting as a cofactor for antioxidant enzymes like Superoxide Dismutase 1 (SOD1).
• Copper dyshomeostasis is linked to neurodegenerative diseases, including Alzheimer's disease.
• Mutations in presenilin genes (PS1 and PS2) are primary causes of early-onset familial Alzheimer's disease and are known to be involved in copper uptake.

Purpose of the Study:

• To investigate the conserved role of presenilin in dietary copper uptake in the fruit fly, Drosophila melanogaster.
• To determine the impact of presenilin on copper levels, antioxidant enzyme activity, and oxidative stress tolerance.

Main Methods:

• Utilized RNA interference (RNAi) to knock down the Drosophila presenilin (PSN) gene specifically in the midgut.
• Assessed copper levels, expression of a copper-responsive EYFP construct, SOD activity, and sensitivity to paraquat in PSN knockdown flies.
• Compared findings with mammalian presenilin studies.

Main Results:

• Midgut-specific PSN knockdown resulted in viable flies with significantly reduced copper levels.
• These flies exhibited increased tolerance to excess dietary copper and reduced SOD activity.
• Expression of a copper-responsive reporter construct was diminished, indicating impaired copper uptake.

Conclusions:

• Presenilin plays a conserved role in mediating dietary copper uptake in the gut.
• Impaired copper uptake due to presenilin deficiency affects antioxidant capacity and oxidative stress response.
• These findings in Drosophila support the link between presenilin, copper metabolism, and oxidative stress, relevant to Alzheimer's disease.