Hypoxia-inducible factor-2α and iron absorptive gene expression in Belgrade rat intestine

Am J Physiol Gastrointest Liver Physiol. 2011 Jul;301(1):G82-90. doi: 10.1152/ajpgi.00538.2010. Epub 2011 Mar 24.

Abstract

The divalent metal transporter (DMT1, Slc11a2) is an important molecule for intestinal iron absorption. In the Belgrade (b/b) rat, the DMT1 G185R mutation markedly decreases intestinal iron absorption. We used b/b rats as a model to examine the genes that could be compensatory for decreased iron absorption. When tissue hypoxia was assayed by detecting pimonidazole HCl adducts, the b/b liver and intestine exhibited more adducts than the +/+ rats, suggesting that hypoxia might signal altered gene expression. Total RNA in the crypt-villus bottom (C-pole) and villus top (V-pole) of +/+, b/b, and iron-fed b/b rats was isolated for gene array analyses. In addition, hepatic hepcidin and intestinal hypoxia-inducible factor-α (Hifα) expression were examined. The results showed that expression of hepatic hepcidin was significantly decreased and intestinal Hif2α was significantly increased in b/b and iron-fed b/b than +/+ rats. In b/b rats, the expression of Tfrc mRNA in the C-pole and of DMT1, Dcytb, FPN1, Heph, Hmox1, and ZIP14 mRNAs in the V-pole were markedly enhanced with increases occurring even in the C-pole. After iron feeding, the increased expression found in b/b rats persisted, except for Heph and ZIP14, which returned to normal levels. Thus in b/b rats depressed liver hepcidin production and activated intestinal Hif2α starting at the C-pole resulted in increasing expression of iron transport genes, including DMT1 G185R, in an attempt to compensate for the anemia in Belgrade rats.

Publication types

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

MeSH terms

  • Anemia / genetics
  • Anemia / metabolism
  • Animals
  • Antimicrobial Cationic Peptides / biosynthesis
  • Basic Helix-Loop-Helix Transcription Factors / metabolism*
  • Cation Transport Proteins / genetics*
  • Cell Hypoxia
  • Gene Expression
  • Hepcidins
  • Intestinal Absorption / genetics*
  • Intestinal Absorption / physiology
  • Intestinal Mucosa / metabolism
  • Intestines / pathology
  • Iron, Dietary / metabolism*
  • Rats
  • Rats, Mutant Strains

Substances

  • Antimicrobial Cationic Peptides
  • Basic Helix-Loop-Helix Transcription Factors
  • Cation Transport Proteins
  • Hamp protein, rat
  • Hepcidins
  • Iron, Dietary
  • solute carrier family 11- (proton-coupled divalent metal ion transporters), member 2
  • endothelial PAS domain-containing protein 1