TY - JOUR
T1 - Both Nramp1 and DMT1 are necessary for efficient macrophage iron recycling
AU - Soe-Lin, Shan
AU - Apte, Sameer S.
AU - Mikhael, Marc R.
AU - Kayembe, Lidia K.
AU - Nie, Guangjun
AU - Ponka, Prem
N1 - Funding Information:
This work was funded by the Canadian Institutes of Health Research (Ottawa, Canada) and the Canadian Blood Services (Ottawa, Canada). The authors would like to sincerely thank Dr. Philippe Gros for his kind gift of cells and antibodies, Anna Dejurga for her patience and assistance with quantitative real-time PCR, and Line Mongeon for her assistance in preparing scanning electron micrographs (cover art for this issue).
Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2010/8
Y1 - 2010/8
N2 - Objective: Divalent metal transporter 1 (DMT1) and natural resistance-associated macrophage protein 1 (Nramp1) are iron transporters that localize, respectively, to the early and late endosomal compartments. DMT1 is ubiquitously expressed, while Nramp1 is found only within macrophages and neutrophils. Our previous studies have identified a role for Nramp1 during macrophage erythrophagocytosis; however, little is known about the function of DMT1 during this process. Materials and Methods: Wild-type RAW264.7 macrophages (RAW), and those stably transfected with Nramp1 (RAW/Nramp1) were treated with either DMT1-small interfering RNA, or with ebselen, a selective inhibitor of DMT1. Results: Although macrophages lacking either functional DMT1 or Nramp1 experienced a moderate reduction in iron recycling efficiency, the ability of macrophages lacking both functional DMT1 and Nramp1 to recycle hemoglobin-derived iron was severely compromised. Compared to macrophages singly deficient in either DMT1 or Nramp1 transport ability, macrophages where DMT1 and Nramp1 were both compromised exhibited an abrogated increase in labile iron pool content, released less iron, and experienced diminished upregulation of ferroportin and heme-oxygenase 1 levels following erythrophagocytosis. Conclusions: These results suggest that although the loss of either Nramp1 or DMT1 transport ability results in minor impairment after erythrophagocytosis, the simultaneous loss of both Nramp1 and DMT1 iron transport activity is detrimental to the iron recycling capacity of the macrophage.
AB - Objective: Divalent metal transporter 1 (DMT1) and natural resistance-associated macrophage protein 1 (Nramp1) are iron transporters that localize, respectively, to the early and late endosomal compartments. DMT1 is ubiquitously expressed, while Nramp1 is found only within macrophages and neutrophils. Our previous studies have identified a role for Nramp1 during macrophage erythrophagocytosis; however, little is known about the function of DMT1 during this process. Materials and Methods: Wild-type RAW264.7 macrophages (RAW), and those stably transfected with Nramp1 (RAW/Nramp1) were treated with either DMT1-small interfering RNA, or with ebselen, a selective inhibitor of DMT1. Results: Although macrophages lacking either functional DMT1 or Nramp1 experienced a moderate reduction in iron recycling efficiency, the ability of macrophages lacking both functional DMT1 and Nramp1 to recycle hemoglobin-derived iron was severely compromised. Compared to macrophages singly deficient in either DMT1 or Nramp1 transport ability, macrophages where DMT1 and Nramp1 were both compromised exhibited an abrogated increase in labile iron pool content, released less iron, and experienced diminished upregulation of ferroportin and heme-oxygenase 1 levels following erythrophagocytosis. Conclusions: These results suggest that although the loss of either Nramp1 or DMT1 transport ability results in minor impairment after erythrophagocytosis, the simultaneous loss of both Nramp1 and DMT1 iron transport activity is detrimental to the iron recycling capacity of the macrophage.
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U2 - 10.1016/j.exphem.2010.04.003
DO - 10.1016/j.exphem.2010.04.003
M3 - Article
C2 - 20394798
AN - SCOPUS:77954541370
SN - 0301-472X
VL - 38
SP - 609
EP - 617
JO - Experimental Hematology
JF - Experimental Hematology
IS - 8
ER -