ZRT/IRT-like protein 14 (ZIP14) promotes the cellular assimilation of iron from transferrin

Ningning Zhao, Junwei Gao, Caroline Enns, Mitchell D. Knutson

Research output: Contribution to journalArticle

100 Citations (Scopus)

Abstract

ZIP14 is a transmembrane metal ion transporter that is abundantly expressed in the liver, heart, and pancreas. Previous studies of HEK 293 cells and the hepatocyte cell lines AML12 and HepG2 established that ZIP14 mediates the uptake of nontransferrin-bound iron, a form of iron that appears in the plasma during pathologic iron overload. In this study we investigated the role of ZIP14 in the cellular assimilation of iron from transferrin, the circulating plasma protein that normally delivers iron to cells by receptor-mediated endocytosis. We also determined the subcellular localization of ZIP14 in HepG2 cells. We found that overexpression of ZIP14 in HEK 293T cells increased the assimilation of iron from transferrin without increasing levels of transferrin receptor 1 or the uptake of transferrin. To allow for highly specific and sensitive detection of endogenous ZIP14 in HepG2 cells, we used a targeted knock-in approach to generate a cell line expressing a FLAG-tagged ZIP14 allele. Confocal microscopic analysis of these cells detected ZIP14 at the plasma membrane and in endosomes containing internalized transferrin. HepG2 cells in which endogenous ZIP14 was suppressed by siRNA assimilated 50% less iron from transferrin compared with controls. The uptake of transferrin, however, was unaffected. We also found that ZIP14 can mediate the transport of iron at pH 6.5, the pH at which iron dissociates from transferrin within the endosome. These results suggest that endosomal ZIP14 participates in the cellular assimilation of iron from transferrin, thus identifying a potentially new role for ZIP14 in iron metabolism.

Original languageEnglish (US)
Pages (from-to)32141-32150
Number of pages10
JournalJournal of Biological Chemistry
Volume285
Issue number42
DOIs
StatePublished - Oct 15 2010

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Transferrin
Iron
Proteins
Hep G2 Cells
HEK293 Cells
Endosomes
Cells
Cell Line
Transferrin Receptors
Iron Overload
Cell membranes
Endocytosis
Metabolism
Liver
Small Interfering RNA
Metal ions
Blood Proteins
Pancreas
Hepatocytes
Metals

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

ZRT/IRT-like protein 14 (ZIP14) promotes the cellular assimilation of iron from transferrin. / Zhao, Ningning; Gao, Junwei; Enns, Caroline; Knutson, Mitchell D.

In: Journal of Biological Chemistry, Vol. 285, No. 42, 15.10.2010, p. 32141-32150.

Research output: Contribution to journalArticle

Zhao, Ningning ; Gao, Junwei ; Enns, Caroline ; Knutson, Mitchell D. / ZRT/IRT-like protein 14 (ZIP14) promotes the cellular assimilation of iron from transferrin. In: Journal of Biological Chemistry. 2010 ; Vol. 285, No. 42. pp. 32141-32150.
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