Expression of the duodenal iron transporters divalent-metal transporter 1 and ferroportin 1 in iron deficiency and iron overload.
OBJECTIVE
Imbalances of iron homeostasis are accompanied by alterations of intestinal iron absorption. The identification of divalent-metal transporter 1 (DMT1) and ferroportin 1 (FP1) has improved our understanding of transmembrane iron trafficking. To gain insight into the regulatory properties of these transporters in the duodenum, we studied their expression in patients with hereditary hemochromatosis (HFE-associated and non-HFE-associated), secondary iron overload, and iron deficiency.


METHODS
DMT1, FP1 messenger RNA (mRNA), and protein expression were analyzed in duodenal biopsy specimens from patients by means of TaqMan real-time polymerase chain reaction, Western blotting technique, and immunohistochemistry.


RESULTS
DMT1 and FP1 mRNA levels are positively correlated with each other in all patient groups (P < 0.001). Moreover, DMT1 and FP1 mRNA levels were significantly increased in patients with iron deficiency, HFE and non-HFE hemochromatosis, whereas they were unchanged in patients with secondary iron overload. Alterations in DMT1 and FP1 mRNA levels were paralleled by comparable changes in the duodenal expression of these proteins. In patients with normal iron status or iron deficiency, significant negative correlations between DMT1, FP1 mRNA, and serum iron parameters were found, which were absent in subjects with primary hemochromatosis.


CONCLUSIONS
DMT1 and FP1 are centrally involved in iron uptake/transfer in the duodenum and in the adaptive changes of iron homeostasis to iron deficiency and overload.
Zoller
H
H
Department of Internal Medicine, Innsbruck, Austria.
Koch
R O
RO
Theurl
I
I
Obrist
P
P
Pietrangelo
A
A
Montosi
G
G
Haile
D J
DJ
Vogel
W
W
Weiss
G
G
D000328:Adult; D000368:Aged; D002352:Carrier Proteins / Q000032:analysis / Q000235:genetics*; D027682:Cation Transport Proteins; D004386:Duodenum / Q000378:metabolism*; D005260:Female; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics; D006432:Hemochromatosis / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D000090463:Iron Deficiencies; D019190:Iron Overload / Q000378:metabolism*; D033862:Iron-Binding Proteins; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000032:analysis; D000098742:Ferroportin; D000099236:Solute Carrier Family 11, Member 2
D002352:Carrier Proteins; D027682:Cation Transport Proteins; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D033862:Iron-Binding Proteins; D012333:RNA, Messenger; D000098742:Ferroportin; D000099236:Solute Carrier Family 11, Member 2