Differences in the cellular zinc content and 5′-nucleotidase activity of normal and acrodermatitis enteropathica (AE) fibroblasts |
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Authors: | Arthur Grider Yu-Femg Lin Stephanie J Muga |
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Institution: | (1) Department of Foods and Nutrition, The University of Georgia, 30602 Athens, GA;(2) Department of Human Ecology, Division of Nutritional Sciences, The University of Texas at Austin, 78712 Austin, TX |
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Abstract: | The acrodermatitis enteropathica (AE) mutation affects zinc (Zn) metabolism in human fibroblasts. We hypothesize that the
mutation affects the cell Zn content, which subsequently affects the activity of various zinc-dependent enzymes, such as 5′-nucleotidase.
Therefore, normal and AE fibroblasts were grown in normal medium containing physiological levels of Zn (16 Μmol/L) for ∼24
h. The medium was replaced by normal medium (16 Μmol/L Zn), Zn-depleted medium (1.5 Μmol/L Zn), or Zn-supplemented medium
(200 Μmol/L Zn) for another 24 h. Regardless of the Zn concentration of the growth medium, the AE fibroblasts contained significantly
less Zn than normal fibroblasts grown in comparable medium. Nevertheless, growth of the fibroblasts in 200 Μmol/L Zn medium
significantly increased the cell Zn content fourfold of both normal and AE fibroblasts. The activity of 5′-nucleotidase in
the AE fibroblasts grown in 16 Μmol/L Zn or 1.5 Μmol/L Zn medium was also significantly lower than in normal fibroblasts.
Changing the growth medium from 16 Μmol/L Zn to 1.5 Μmol/L Zn medium did not affect the activity of the enzyme in either genotype.
Cells grown in 200 Μmol/L Zn medium exhibited threefold greater 5′-nucleotidase activity in AE fibroblasts, but had no affect
on enzyme activity in normal cells. In summary, altering the cell Zn content of normal fibroblasts did not result in a significant
change in their 5′ -nucleotidase activity. However, AE fibroblasts grown in 200 Μmol/L Zn medium exhibited recovery of their
5′-nucleotidase activity to normal levels. These results support the hypothesis that the AE mutation affects the cellular
Zn content. The lower cell Zn content subsequently affects the activity of 5′-nucleotidase. |
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Keywords: | Human fibroblast acrodermatitis enteropathica zinc 5′ -nucleotidase |
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