Characterization of zinc uptake by mouse primary cultured astrocytes and microglia

To elucidate the regulatory mechanism for extracellular zinc in the CNS, we examined the zinc uptake characteristics in mouse astrocytes and microglia. Zinc was taken up into the two cell types time-dependently, and the cell-to-medium concentration (C/M) ratio in the initial uptake phase in astrocyt...

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Bibliographic Details
Published in:Metallomics 2015-07, Vol.7 (7), p.1067-1077
Main Authors: Segawa, Shohei, Tatsumi, Nao, Ohishi, Akihiro, Nishida, Kentaro, Nagasawa, Kazuki
Format: Article
Language:English
Subjects:
Animals
Astrocytes - cytology
Astrocytes - metabolism
Biological Transport
Cation Transport Proteins - genetics
Cation Transport Proteins - metabolism
Cells, Cultured
Gene Knockdown Techniques
Mice
Microglia - cytology
Microglia - metabolism
Zinc - metabolism
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Summary:To elucidate the regulatory mechanism for extracellular zinc in the CNS, we examined the zinc uptake characteristics in mouse astrocytes and microglia. Zinc was taken up into the two cell types time-dependently, and the cell-to-medium concentration (C/M) ratio in the initial uptake phase in astrocytes was significantly smaller than that in microglia, while in the steady state phase, there was no difference in their C/M ratios. In both astrocytes and microglia, the zinc uptake was mediated, at least in part, by high- and low-affinity systems. There were no differences for both in the Km values for zinc uptake between astrocytes and microglia, and those for the low-affinity system in both cell types were the same as that for mouse ZIP1 reported previously. On the other hand, the Vmax values for both systems were greater in microglia than in astrocytes. Among ZIP isoforms, expression of ZIP1 was high in astrocytes and microglia. Nickel, a competitive inhibitor of ZIP1, and ZIP1 knock-down decreased zinc uptake by both types of cells. Overall, it is demonstrated that astrocytes and microglia had a similar uptake system for zinc including ZIP1, and the differences found in their uptake profiles imply that they play different roles in the regulation of extracellular zinc to maintain brain homeostasis.
ISSN:1756-5901
1756-591X
DOI:10.1039/c5mt00085h