Evidence for a sequential transfer of iron amongst ferritin, transferrin and transferrin receptor during duodenal absorption of iron in rat and human

Kolachala, Vasantha L.; Sesikeran, B.; Nair, K. Madhavan

doi:10.3748/wjg.v13.i7.1042

Cited by 16 publications

(13 citation statements)

References 33 publications

(34 reference statements)

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“…In addition, the presence of Scara5 in intestinal epithelia cells has not been reported. TfR1 is yet another possible candidate; it is expressed in enterocytes where it mediates basolateral iron uptake (37), and the enterocyte apical membrane contains TfR1 (21). Hence, TfR1 is present in the right cell type and in the correct cellular localization.…”

Section: Discussionmentioning

confidence: 99%

Endocytic pathway of exogenous iron-loaded ferritin in intestinal epithelial (Caco-2) cells

Antileo

Garri

Tapia

et al. 2013

American Journal of Physiology-Gastrointestinal and Liver Physi

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Artículo de publicación ISIFerritin, a food constituent of animal and vegetal origin, is a source of dietary iron. Its hollow central cavity has the capacity to store up to 4,500 atoms of iron, so its potential as an iron donor is advantageous to heme iron, present in animal meats and inorganic iron of mineral or vegetal origin. In intestinal cells, ferritin internalization by endocytosis results in the release of its iron into the cytosolic labile iron pool. The aim of this study was to characterize the endocytic pathway of exogenous ferritin absorbed from the apical membrane of intestinal epithelium Caco-2 cells, using both transmission electron microscopy and fluorescence confocal microscopy. Confocal microscopy revealed that endocytosis of exogenous AlexaFluor 488-labeled ferritin was initiated by its engulfment by clathrin-coated pits and internalization into early endosomes, as determined by codistribution with clathrin and early endosome antigen 1 (EEA1). AlexaFluor 488-labeled ferritin also codistributed with the autophagosome marker microtubule-associated protein 1 light chain 3 (LC3) and the lysosome marker lysosomal-associated membrane protein 2 (LAMP2). Transmission electron microscopy revealed that exogenously added ferritin was captured in plasmalemmal pits, double-membrane compartments, and multivesicular bodies considered as autophagosomes and lysosomes. Biochemical experiments revealed that the lysosome inhibitor chloroquine and the autophagosome inhibitor 3-methyladenine (3-MA) inhibited degradation of exogenously added 131I-labeled ferritin. This evidence is consistent with a model in which exogenous ferritin is internalized from the apical membrane through clathrin-coated pits, and then follows a degradation pathway consisting of the passage through early endosomes, autophagosomes, and autolysosomes.This work was financed by project ICM-P05-001-F from the Millennium Scientific Initiative, Ministerio de Economía, Chile (to M. T. Núñez), and by Grants 1070840 from Fondo Nacional de Ciencia y Tecnología (to M. T. Núñez) and ACT 1111 (to S. Lavandero and M. Chiong)

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Section: Discussionmentioning

confidence: 99%

Endocytic pathway of exogenous iron-loaded ferritin in intestinal epithelial (Caco-2) cells

Antileo

Garri

Tapia

et al. 2013

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…The nature of the LIP-binding counterpart is unknown, but it has been ascribed to diverse low-molecular-weight substances such as phosphate, nucleotides, hydroxyl, amino, and sulfydryl groups (23,36). From the LIP, iron distributes into ferritin and other iron-requiring proteins (15,24). Iron exit from the enterocyte is mediated by the efflux transporter ferroportin (FPN), the only member of the SLC40 family of transporters and the first reported protein that mediates the exit of iron from cells (30).…”

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confidence: 99%

Iron supply determines apical/basolateral membrane distribution of intestinal iron transporters DMT1 and ferroportin 1

Núñez

Tapia

Rojas³

et al. 2010

American Journal of Physiology-Cell Physiology

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Núñez MT, Tapia V, Rojas A, Aguirre P, Gómez F, Nualart F. Iron supply determines apical/basolateral membrane distribution of intestinal iron transporters DMT1 and ferroportin 1. Am J Physiol Cell Physiol 298: C477-C485, 2010. First published December 9, 2009; doi:10.1152/ajpcell.00168.2009.-Intestinal iron absorption comprises the coordinated activity of the influx transporter divalent metal transporter 1 (DMT1) and the efflux transporter ferroportin (FPN). In this work, we studied the movement of DMT1 and FPN between cellular compartments as a function of iron supply. In rat duodenum, iron gavage resulted in the relocation of DMT1 to basal domains and the internalization of basolateral FPN. Considerable FPN was also found in apical domains. In Caco-2 cells, the apical-to-basal movement of cyan fluorescent protein-tagged DMT1 was complete 90 min after the addition of iron. Steady-state membrane localization studies in Caco-2 cells revealed that iron status determined the apical/ basolateral membrane distribution of DMT1 and FPN. In agreement with the membrane distribution of the transporters, 55 Fe flux experiments revealed inward and outward iron fluxes at both membrane domains. Antisense oligonucleotides targeted to DMT1 or FPN inhibited basolateral iron uptake and apical iron efflux, respectively, indicating the participation of DMT1 and FPN in these fluxes. The fluxes were regulated by the iron supply; increased iron reduced apical uptake and basal efflux and increased basal uptake and apical efflux. These findings suggest a novel mechanism of regulation of intestinal iron absorption based on inward and outward fluxes at both membrane domains, and repositioning of DMT1 and FPN between membrane and intracellular compartments as a function of iron supply. This mechanism should be complementary to those based in the transcriptional or translational regulation of iron transport proteins.intestinal iron absorption; divalent metal transporter 1; mucosal block IN THE ABSENCE OF A CONTROLLED excretion mechanism, iron levels in the body are regulated mainly by its passage through the duodenum epithelia. Traditionally, intestinal iron absorption is divided into three sequential steps: the uptake of iron from the intestinal lumen; an intracellular phase, in which iron binds to cytosolic components; and a transfer step, in which iron passes from the cells to the blood plasma. The uptake of iron from the lumen of the intestine is mediated by the Fe 2ϩ -H ϩ cotransporter divalent metal transporter 1 (DMT1) (19).Once inside the enterocyte, iron integrates into a cytosolic pool of weakly bound iron called the labile iron pool (LIP) (16,25). The nature of the LIP-binding counterpart is unknown, but it has been ascribed to diverse low-molecular-weight substances such as phosphate, nucleotides, hydroxyl, amino, and sulfydryl groups (23,36). From the LIP, iron distributes into ferritin and other iron-requiring proteins (15, 24). Iron exit from the enterocyte is mediated by the efflux transporter ferroportin (FPN), the only m...

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“…Because of iron's insolubility and potential toxicity under physiological conditions, special molecules have evolved for its acquisition, transport and storage in soluble, nontoxic forms (Kolachala et al, 2007). The mechanism and control of iron uptake by the gut has puzzled investigators in both in vivo and in vitro studies (LatundeDada et al, 1998;Morgan and Oates, 2002;Latunde-Dada, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, in vitro systems or animal models have different iron metabolism behaviour when compared with humans (Latunde-Dada et al, 1998;Vaghefi et al, 2005;Patterson et al, 2008;Quintero et al, 2008). Studies related to iron involve different procedures including isotopic techniques, simulated enzymatic gastrointestinal digestion or hemoglobin (Hb) depletion-repletion (Srigiridhar and Nair, 2000;Beach et al, 2003;Vaghefi et al, 2005;Kolachala et al, 2007;Quintero et al, 2008). This paper reviews the main experimental models commonly used in iron metabolic and nutritional studies, including their advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

“…Absorption is regulated according to the body's needs by hepcidin, a small cysteine-rich cationic peptide currently considered as the most important factor controlling iron absorption (Lynch, 2007). A study using human biopsies and rats concluded that the intestine iron uptake takes place through a sequential transfer involving interaction of luminal transferrin, transferrin-TFR and ferritin (Kolachala et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Advantages and disadvantages of the animal models v. in vitro studies in iron metabolism: a review

García¹,

Díaz-Castro

2013

Animal

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Iron deficiency is the most common nutritional deficiency in the world. Special molecules have evolved for iron acquisition, transport and storage in soluble, nontoxic forms. Studies about the effects of iron on health are focused on iron metabolism or nutrition to prevent or treat iron deficiency and anemia. These studies are focused in two main aspects: (1) basic studies to elucidate iron metabolism and (2) nutritional studies to evaluate the efficacy of iron supplementation to prevent or treat iron deficiency and anemia. This paper reviews the advantages and disadvantages of the experimental models commonly used as well as the methods that are more used in studies related to iron. In vitro studies have used different parts of the gut. In vivo studies are done in humans and animals such as mice, rats, pigs and monkeys. Iron metabolism is a complex process that includes interactions at the systemic level. In vitro studies, despite physiological differences to humans, are useful to increase knowledge related to this essential micronutrient. Isotopic techniques are the most recommended in studies related to iron, but their high cost and required logistic, making them difficult to use. The depletion--repletion of hemoglobin is a method commonly used in animal studies. Three depletion--repletion techniques are mostly used: hemoglobin regeneration efficiency, relative biological values (RBV) and metabolic balance, which are official methods of the association of official analytical chemists. These techniques are well-validated to be used as studies related to iron and their results can be extrapolated to humans. Knowledge about the main advantages and disadvantages of the in vitro and animal models, and methods used in these studies, could increase confidence of researchers in the experimental results with less costs.

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Evidence for a sequential transfer of iron amongst ferritin, transferrin and transferrin receptor during duodenal absorption of iron in rat and human

Cited by 16 publications

References 33 publications

Endocytic pathway of exogenous iron-loaded ferritin in intestinal epithelial (Caco-2) cells

Endocytic pathway of exogenous iron-loaded ferritin in intestinal epithelial (Caco-2) cells

Iron supply determines apical/basolateral membrane distribution of intestinal iron transporters DMT1 and ferroportin 1

Advantages and disadvantages of the animal models v. in vitro studies in iron metabolism: a review

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