ZIP14 and DMT1 in the liver, pancreas, and heart are differentially regulated by iron deficiency and overload: implications for tissue iron uptake in iron-related disorders

Haematologica. 2013 Jul;98(7):1049-57. doi: 10.3324/haematol.2012.072314. Epub 2013 Jan 24.

Abstract

The liver, pancreas, and heart are particularly susceptible to iron-related disorders. These tissues take up plasma iron from transferrin or non-transferrin-bound iron, which appears during iron overload. Here, we assessed the effect of iron status on the levels of the transmembrane transporters, ZRT/IRT-like protein 14 and divalent metal-ion transporter-1, which have both been implicated in transferrin- and non-transferrin-bound iron uptake. Weanling male rats (n=6/group) were fed an iron-deficient, iron-adequate, or iron-overloaded diet for 3 weeks. ZRT/IRT-like protein 14, divalent metal-ion transporter-1 protein and mRNA levels in liver, pancreas, and heart were determined by using immunoblotting and quantitative reverse transcriptase polymerase chain reaction analysis. Confocal immunofluorescence microscopy was used to localize ZRT/IRT-like protein 14 in the liver and pancreas. ZRT/IRT-like protein 14 and divalent metal-ion transporter-1 protein levels were also determined in hypotransferrinemic mice with genetic iron overload. Hepatic ZRT/IRT-like protein 14 levels were found to be 100% higher in iron-loaded rats than in iron-adequate controls. By contrast, hepatic divalent metal-ion transporter-1 protein levels were 70% lower in iron-overloaded animals and nearly 3-fold higher in iron-deficient ones. In the pancreas, ZRT/IRT-like protein 14 levels were 50% higher in iron-overloaded rats, and in the heart, divalent metal-ion transporter-1 protein levels were 4-fold higher in iron-deficient animals. At the mRNA level, ZRT/IRT-like protein 14 expression did not vary with iron status, whereas divalent metal-ion transporter-1 expression was found to be elevated in iron-deficient livers. Immunofluorescence staining localized ZRT/IRT-like protein 14 to the basolateral membrane of hepatocytes and to acinar cells of the pancreas. Hepatic ZRT/IRT-like protein 14, but not divalent metal-ion transporter-1, protein levels were elevated in iron-loaded hypotransferrinemic mice. In conclusion, ZRT/IRT-like protein 14 protein levels are up-regulated in iron-loaded rat liver and pancreas and in hypotransferrinemic mouse liver. Divalent metal-ion transporter-1 protein levels are down-regulated in iron-loaded rat liver, and up-regulated in iron-deficient liver and heart. Our results provide insight into the potential contributions of these transporters to tissue iron uptake during iron deficiency and overload.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anemia, Iron-Deficiency / metabolism*
  • Animals
  • Cation Transport Proteins / antagonists & inhibitors
  • Cation Transport Proteins / biosynthesis*
  • Cation Transport Proteins / metabolism*
  • Cation Transport Proteins / physiology
  • Down-Regulation / physiology*
  • Female
  • HEK293 Cells
  • Heart / physiology
  • Hep G2 Cells
  • Humans
  • Iron / metabolism*
  • Iron Overload / metabolism*
  • Liver / metabolism
  • Male
  • Mice
  • Mice, 129 Strain
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Pancreas / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Tissue Distribution / physiology
  • Up-Regulation / physiology*

Substances

  • Cation Transport Proteins
  • SLC39A14 protein, mouse
  • solute carrier family 11- (proton-coupled divalent metal ion transporters), member 2
  • Iron