Systemic regulation of Hephaestin and Ireg1 revealed in studies of genetic and nutritional iron deficiency.
Hephaestin is a membrane-bound multicopper ferroxidase necessary for iron egress from intestinal enterocytes into the circulation. Mice with sex-linked anemia (sla) have a mutant form of Hephaestin and a defect in intestinal basolateral iron transport, which results in iron deficiency and anemia. Ireg1 (SLC11A3, also known as Ferroportin1 or Mtp1) is the putative intestinal basolateral iron transporter. We compared iron levels and expression of genes involved in iron uptake and storage in sla mice and C57BL/6J mice fed iron-deficient, iron-overload, or control diets. Both iron-deficient wild-type mice and sla mice showed increased expression of Heph and Ireg1 mRNA, compared to controls, whereas only iron-deficient wild-type mice had increased expression of the brush border transporter Dmt1. Unlike iron-deficient mice, sla mouse enterocytes accumulated nonheme iron and ferritin. These results indicate that Dmt1 can be modulated by the enterocyte iron level, whereas Hephaestin and Ireg1 expression respond to systemic rather than local signals of iron status. Thus, the basolateral transport step appears to be the primary site at which the small intestine responds to alterations in body iron requirements.
Department of Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720, USA.
Huijun
H
Chen
Trent
T
Su
Zouhair K
ZK
Attieh
Tama C
TC
Fox
Andrew T
AT
McKie
Gregory J
GJ
Anderson
Chris D
CD
Vulpe
D018798:Anemia, Iron-Deficiency / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D000918:Antibody Specificity; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D004032:Diet; D020895:Enterocytes / Q000378:metabolism; D005293:Ferritins / Q000097:blood; D015870:Gene Expression; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism; D019190:Iron Overload / Q000235:genetics / Q000378:metabolism; D019266:Iron, Dietary / Q000097:blood / Q000493:pharmacokinetics; D033862:Iron-Binding Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009747:Nutritional Physiological Phenomena; D012333:RNA, Messenger / Q000032:analysis; D000098742:Ferroportin; D000099236:Solute Carrier Family 11, Member 2
D027682:Cation Transport Proteins; D005293:Ferritins; D019266:Iron, Dietary; D033862:Iron-Binding Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D000098742:Ferroportin; D000099236:Solute Carrier Family 11, Member 2; C492164:HEPH protein, human; C117324:Heph protein, mouse