Subcellular localization of ferritin and iron taken up by rat hepatocytes

The subcellular localization of ferritin and its iron taken up by rat hepatocytes was investigated by sucrose-density-gradient ultracentrifugation of cell homogenates. After incubation of hepatocytes with 125I-labelled [59Fe]ferritin, cells incorporate most of the labels into structures equilibratin...

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Bibliographic Details
Published in:Biochemical journal 1989-09, Vol.262 (2), p.685-688
Main Authors: Sibille, J C, Ciriolo, M, Kondo, H, Crichton, R R, Aisen, P
Format: Article
Language:English
Subjects:
Animals
Cell Fractionation
Cytosol - metabolism
ferritin
Ferritins - metabolism
iron
Iron - metabolism
Liver - metabolism
Liver - ultrastructure
Lysosomes - metabolism
Mitochondria, Liver - metabolism
Rats
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Summary:The subcellular localization of ferritin and its iron taken up by rat hepatocytes was investigated by sucrose-density-gradient ultracentrifugation of cell homogenates. After incubation of hepatocytes with 125I-labelled [59Fe]ferritin, cells incorporate most of the labels into structures equilibrating at densities where acid phosphatase and cytochrome c oxidase are found, suggesting association of ferritin and its iron with lysosomes or mitochondria. Specific solubilization of lysosomes by digitonin treatment indicates that, after 8 h incubation, most of the 125I is recovered in lysosomes, whereas 59Fe is found in mitochondria as well as in lysosomes. As evidenced by gel chromatography of supernatant fractions, 59Fe accumulates with time in cytosolic ferritin. To account for these results a model is proposed in which ferritin, after being endocytosed by hepatocytes, is degraded in lysosomes, and its iron is released and re-incorporated into cytosolic ferritin and, to a lesser extent, into mitochondria.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2620685