Zinc Transport Protein-1 (ZnT1) Contributes to Zn2+ Efflux in Primary Cultures of Rat Cortical Neurons

Zinc homeostasis is maintained through a complex network of chelating and transporting proteins. Disruption of this network can have dire implications such as Alzheimer ’s disease and Acrodermatitis Enteropathica. Neuronal zinc homeostasis is still being investigated and this study looks at the plasma membrane bound protein, ZnT1. Using RNA interference to knockdown protein expression in post-mitotic rat neurons, the hypothesis that ZnT1 contributes to the direct efflux of zinc from the cytoplasmic pool was tested. ZnT1 knockdown cells were compared side by side to non-transfected cells during zinc loading and efflux using the zinc selective fluorophore, ZnAF-2F. Cells were zinc perfused with a 10μM ZnCl2 for 60 minutes then perfused with 0.1mM EDTA to allow the active efflux of zinc. ZnT1 knockdown cells maintained an increased ZnAF-2F signal while neighboring cells lost about 20% of the signal indicating the ZnT1’s involvement in the efflux of zinc.