title: Iron handling and gene expression of the divalent metal transporter, DMT1, in the kidney of the anemic Belgrade (b) rat.
abstract: BACKGROUND
  We have previously shown that the rat kidney reabsorbs metabolically significant amounts of iron and that it expresses the divalent metal transporter 1, DMT1. The Belgrade (b) rat carries a mutation in DMT1 gene, which causes hypochromic, microcytic anemia due to impaired intestinal iron absorption and transport of iron out of the transferrin cycle endosome. In the duodenum of b/b rats, expression of DMT1 mRNA and protein is increased, suggesting a feedback regulation by iron stores. The aim of this study was to investigate iron handling and DMT1 expression in the kidneys of Belgrade rats.
  
  
  METHODS
  Animals were maintained for 3 weeks on a synthetic diet containing 185 mg/kg iron (FeSO4), after which functional and molecular parameters were analyzed in male heterozygous (+/b) and homozygous (b/b) rats (N = 4 to 6 for each group).
  
  
  RESULTS
  Serum iron concentration was significantly higher in b/b compared to +/b rats while urinary iron excretion rates were unchanged in b/b compared to +/b rats. Northern analysis using a rat DMT1 probe showed comparable mRNA levels between +/b and b/b animals. Western analysis and immunofluorescence microscopy performed using a polyclonal antibody against rat DMT1 showed that DMT1-specific immunoreactivity was almost absent in the kidneys of b/b rats compared to that seen in +/b animals.
  
  
  CONCLUSIONS
  Our results indicate that the G185R mutation of DMT1 causes protein instability in the kidneys of b/b rats. Given that +/b and b/b rats excrete comparable amounts of iron, the lack of DMT1 protein is compensated by an alternative, yet to be identified, mechanism.
authors.affiliation: School of Biological Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Carole J
authors.initials: CJ
authors.lastname: Ferguson
authors.forename: Mark
authors.initials: M
authors.lastname: Wareing
authors.forename: Mathieu
authors.initials: M
authors.lastname: Delannoy
authors.forename: Robert
authors.initials: R
authors.lastname: Fenton
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: McLarnon
authors.forename: Nicholas
authors.initials: N
authors.lastname: Ashton
authors.forename: Alan G
authors.initials: AG
authors.lastname: Cox
authors.forename: Raymond F T
authors.initials: RF
authors.lastname: McMahon
authors.forename: Laura M
authors.initials: LM
authors.lastname: Garrick
authors.forename: Roger
authors.initials: R
authors.lastname: Green
authors.forename: Craig P
authors.initials: CP
authors.lastname: Smith
authors.forename: Daniela
authors.initials: D
authors.lastname: Riccardi
mesh_terms: D000740:Anemia / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D004326:Drinking; D004435:Eating; D005243:Feces; D005260:Female; D007501:Iron / Q000097:blood* / Q000652:urine*; D033862:Iron-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D008274:Magnesium / Q000097:blood; D008297:Male; D017354:Point Mutation; D011188:Potassium / Q000097:blood; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011922:Rats, Mutant Strains; D014556:Urine; D000099236:Solute Carrier Family 11, Member 2
chemical_list: D027682:Cation Transport Proteins; D007501:Iron; D033862:Iron-Binding Proteins; D008274:Magnesium; D011188:Potassium; D012333:RNA, Messenger; D000099236:Solute Carrier Family 11, Member 2