Abstract
BACKGROUND: Although the importance of adequate zinc intake has been known for decades, the estimated global prevalence of zinc deficiency remains high. This substantiates the need for a specific and sensitive status assessment tool. OBJECTIVE: The objective was to evaluate erythrocyte zinc transporters as candidate molecules with the potential of being a biomarker of dietary zinc status in humans. DESIGN: A 24-d observational study with acclimation (7 d, 10.4 mg Zn/d), zinc-depletion (10 d, 0.3 mg Zn/d), and zinc-repletion (7 d, 29.5 mg Zn/d) phases was conducted in healthy men (n = 9). Proteomic approaches including Western blot analyses and tandem mass spectrometry were implemented to identify the zinc responsiveness of selected red blood cell membrane proteins. RESULTS: Zinc transporter 1 (ZnT1) and Zrt/Irt-like proteins ZIP8 and ZIP10 were detected in human erythrocyte membranes. No effects of short-term dietary zinc depletion were observed on the amounts of these proteins. However, changes in a cytoskeletal protein, dematin, by zinc depletion were identified through the nonspecific signals produced by an anti-ZIP8 antibody. This response was further validated by a dematin-specific antibody and with erythrocytes collected from mice fed a zinc-deficient diet. CONCLUSIONS: The presence of ZnT1, ZIP8, and ZIP10 in human red blood cells implicates their role in the regulation of cellular zinc metabolism in the human erythroid system. The zinc responsiveness of membrane dematin suggests its capability to serve as a biomarker for dietary zinc depletion and its involvement in impaired erythroid membrane fragility by zinc restriction. This trial was registered at clinicaltrials.gov as NCT01221129.