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Antileo E, Garri C, Tapia V, Muñoz JP, Chiong M, Nualart F, Lavandero S, Fernández J, Núñez MT. Endocytic pathway of exogenous iron-loaded ferritin in intestinal epithelial (Caco-2) cells. Am J Physiol Gastrointest Liver Physiol 2013; 304:G655-61. [PMID: 23370673 DOI: 10.1152/ajpgi.00472.2012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Ferritin, 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 (131)I-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.
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Affiliation(s)
- Elmer Antileo
- Facultad de Ciencias, Departamento de Biología, Universidad de Chile, Santiago, Chile
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202
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Ojala JRM, Pikkarainen T, Elmberger G, Tryggvason K. Progressive reactive lymphoid connective tissue disease and development of autoantibodies in scavenger receptor A5-deficient mice. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 182:1681-95. [PMID: 23499552 DOI: 10.1016/j.ajpath.2013.01.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 12/17/2012] [Accepted: 01/14/2013] [Indexed: 10/27/2022]
Abstract
Scavenger receptor A5 (SCARA5) is a member of the class A scavenger receptors, with most similarity to SCARA1 (SR-A) and SCARA2 (MARCO), which are primarily expressed by macrophages and dendritic cells, in which they participate in clearance of various polyanionic macromolecules, pollution particles, and pathogens. The biological role of SCARA5 has been unknown. Herein, we show that SCARA5 is an endocytotic receptor whose ligand repertoire includes the typical scavenger receptor ligands, whole bacteria, and purified Gram-negative bacterial lipopolysaccharide. In contrast to expression of SCARA1 and SCARA2 in immune cells, SCARA5 is found in a subset of fibroblast-like cells in the interstitial stroma of most organs, with additional expression in the epithelial cells of testis and choroid plexus. SCARA5-null mice develop with age lymphoid cell accumulation in many organs, in particular the lungs, and show decreased endocytotic function in fibroblasts. Furthermore, about one-third of the mice develop antinuclear antibodies. These disturbances are reminiscent of those found in many human autoimmune connective tissue disorders, which suggests that defects in fibroblast SCARA5 can underlie some forms of autoimmune disease.
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Affiliation(s)
- Juha Risto Matias Ojala
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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203
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Abstract
Ferritins, highly symmetrical protein nanocages, are reactors for Fe2+ and dioxygen or hydrogen peroxide that are found in all kingdoms of life and in many different cells of multicellular organisms. They synthesize iron concentrates required for cells to make cofactors of iron proteins (heme, FeS, mono and diiron). The caged ferritin biominerals, Fe2O3•H2O are also antioxidants, acting as sinks for iron and oxidants scavenged from damaged proteins; genetic regulation of ferritin biosynthesis is sensitive to both iron and oxidants. Here, the emphasis here is ferritin oxidoreductase chemistry, ferritin ion channels for Fe 2+ transit into and out of the protein cage and Fe 3+ O mineral nucleation, and uses of ferritin cages in nanocatalysis and nanomaterial synthesis. The Fe2+ and O ferritin protein reactors, likely critical in the transition from anaerobic to aerobic life on earth, play central, contemporary roles that balance iron and oxygen chemistry in biology and have emerging roles in nanotechnology.
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Affiliation(s)
- Elizabeth C. Theil
- Children’s Hospital Oakland Research Institute, University of California, Berkeley
- Department of Nutritional Science and Toxicology, University of California, Berkeley
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204
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Ferritin stimulates breast cancer cells through an iron-independent mechanism and is localized within tumor-associated macrophages. Breast Cancer Res Treat 2013; 137:733-44. [PMID: 23306463 DOI: 10.1007/s10549-012-2405-x] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 12/29/2012] [Indexed: 10/27/2022]
Abstract
Tumor-associated macrophages play a critical role in breast tumor progression; however, it is still unclear what effector molecular mechanisms they employ to impact tumorigenesis. Ferritin is the primary intracellular iron storage protein and is also abundant in circulation. In breast cancer patients, ferritin is detected at higher levels in both serum and tumor lysates, and its increase correlates with poor clinical outcome. In this study, we comprehensively examined the distribution of ferritin in normal and malignant breast tissue at different stages in tumor development. Decreased ferritin expression in cancer cells but increased infiltration of ferritin-rich CD68-positive macrophages was observed with increased tumor histological grade. Interestingly, ferritin stained within the stroma surrounding tumors suggesting local release within the breast. In cell culture, macrophages, but not breast cancer cells, were capable of ferritin secretion, and this secretion was further increased in response to pro-inflammatory cytokines. We next examined the possible functional significance of extracellular ferritin in a breast cancer cell culture model. Ferritin stimulated the proliferation of the epithelial breast cancer cell lines MCF7 and T47D. Moreover, this proliferative effect was independent of the iron content of ferritin and did not increase intracellular iron levels in cancer cells indicating a novel iron-independent function for this protein. Together, these findings suggest that the release of ferritin by infiltrating macrophages in breast tumors may represent an inflammatory effector mechanism by which ferritin directly stimulates tumorigenesis.
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205
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Heruth DP, Gibson M, Grigoryev DN, Zhang LQ, Ye SQ. RNA-seq analysis of synovial fibroblasts brings new insights into rheumatoid arthritis. Cell Biosci 2012; 2:43. [PMID: 23259760 PMCID: PMC3560277 DOI: 10.1186/2045-3701-2-43] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 11/23/2012] [Indexed: 12/15/2022] Open
Abstract
Background Rheumatoid arthritis (RA) is a chronic autoimmune-disease of unknown origin that primarily affects the joints and ultimately leads to their destruction. Growing evidence suggests that synvovial fibroblasts play important roles in the initiation and the perpetuation of RA but underlying molecular mechanisms are not understood fully. In the present study, Illumina RNA sequencing was used to profile two human normal control and two rheumatoid arthritis synvovial fibroblasts (RASFs) transcriptomes to gain insights into the roles of synvovial fibroblasts in RA. Results We found that besides known inflammatory and immune responses, other novel dysregulated networks and pathways such as Cell Morphology, Cell-To-Cell Signaling and Interaction, Cellular Movement, Cellular Growth and Proliferation, and Cellular Development, may all contribute to the pathogenesis of RA. Our study identified several new genes and isoforms not previously associated with rheumatoid arthritis. 122 genes were up-regulated and 155 genes were down-regulated by at least two-fold in RASFs compared to controls. Of note, 343 known isoforms and 561 novel isoforms were up-regulated and 262 known isoforms and 520 novel isoforms were down-regulated by at least two-fold. The magnitude of difference and the number of differentially expressed known and novel gene isoforms were not detected previously by DNA microarray. Conclusions Since the activation and proliferation of RASFs has been implicated in the pathogenesis of rheumatoid arthritis, further in-depth follow-up analysis of the transcriptional regulation reported in this study may shed light on molecular pathogenic mechanisms underlying synovial fibroblasts in arthritis and provide new leads of potential therapeutic targets.
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Affiliation(s)
- Daniel P Heruth
- Department of Pediatrics, Children's Mercy Hospitals and Clinics, University of Missouri School of Medicine, 2401 Gillham Road, Kansas City, MO, 64108, USA.
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206
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Tang X, Zhou B. Ferritin is the key to dietary iron absorption and tissue iron detoxification in Drosophila melanogaster. FASEB J 2012; 27:288-98. [PMID: 23064556 DOI: 10.1096/fj.12-213595] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Mammalian ferritin is predominantly in the cytosol, with a minor portion found in plasma. In most insects, including Drosophila melanogaster, ferritin belongs to the secretory type. The functional role of secretory ferritin in iron homeostasis remains poorly understood in insects as well as in mammalians. Here we used Drosophila to dissect the involvement of ferritin in insect iron metabolism. Midgut-specific knockdown of ferritin resulted in iron accumulation in the gut but systemic iron deficiency (37% control), accompanied by retarded development and reduced survival (3% survival), and was rescued by dietary iron supplementation (50% survival) or exacerbated by iron depletion (0% survival). These results suggest an essential role of ferritin in removing iron from enterocytes across the basolateral membrane. Expression of wild-type ferritin in the midgut, especially in the iron cell region, could significantly rescue ferritin-null mutants (first-instar larvae rescued up to early adults), indicating iron deficiency as the major cause of early death for ferritin flies. In many nonintestinal tissues, tissue-specific ferritin knockdown also caused local iron accumulation (100% increase) and resulted in severe tissue damage, as evidenced by cell loss. Overall, our study demonstrated Drosophila ferritin is essential to two key aspects of iron homeostasis: dietary iron absorption and tissue iron detoxification.
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Affiliation(s)
- Xiaona Tang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China
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207
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Yan N, Zhang S, Yang Y, Cheng L, Li C, Dai L, Dai L, Zhang X, Fan P, Tian H, Wang R, Chen X, Su X, Li Y, Zhang J, Du T, Wei Y, Deng H. Therapeutic upregulation of Class A scavenger receptor member 5 inhibits tumor growth and metastasis. Cancer Sci 2012; 103:1631-9. [PMID: 22642751 DOI: 10.1111/j.1349-7006.2012.02350.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 05/07/2012] [Accepted: 05/15/2012] [Indexed: 02/05/2023] Open
Abstract
Class A scavenger receptor member 5 (SCARA5) is a new member of the Class A scavenger receptors that has been proposed recently as a novel candidate tumor suppressor gene in human hepatocellular carcinoma. In the present study, we found that SCARA5 expression was frequently downregulated in various cancer cell lines and tumor samples. In addition, upregulation of SCARA5 expression in human cancer cell line (U251) led to a significant decrease in cell proliferation, clone formation, migration, and invasion in vitro. Furthermore, systemic treatment of tumor-bearing mice with SCARA5-cationic liposome complex not only reduced the growth of subcutaneous human glioma tumors, but also markedly suppressed the spontaneous formation of lung metastases. Similar results were obtained in another experiment using mice bearing experimental A549 lung metastases. Compared with the untreated control group, mice treated with SCARA5 exhibited reductions in both spontaneous U251 and experimental A549 lung metastases rates of 77.3% and 70.2%, respectively. Western blot analysis was used to explore the molecular mechanisms involved and revealed that SCARA5 physically associated with focal adhesion kinase. Interestingly, upregulation of SCARA5 inactivated signal transducer and activator of transcription 3, as well as downstream signaling including cyclinB1, cyclinD1, AKT, survivin, matrix metalloproteinase-9 and vascular endothelial growth factor-A. Overall, the findings of the present study provide the first evidence that SCARA5 might be a promising target for the development of new antimetastatic agents for the gene therapy of cancer.
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Affiliation(s)
- Nv Yan
- State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, China
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208
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Pantopoulos K, Porwal SK, Tartakoff A, Devireddy L. Mechanisms of mammalian iron homeostasis. Biochemistry 2012; 51:5705-24. [PMID: 22703180 DOI: 10.1021/bi300752r] [Citation(s) in RCA: 399] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Iron is vital for almost all organisms because of its ability to donate and accept electrons with relative ease. It serves as a cofactor for many proteins and enzymes necessary for oxygen and energy metabolism, as well as for several other essential processes. Mammalian cells utilize multiple mechanisms to acquire iron. Disruption of iron homeostasis is associated with various human diseases: iron deficiency resulting from defects in the acquisition or distribution of the metal causes anemia, whereas iron surfeit resulting from excessive iron absorption or defective utilization causes abnormal tissue iron deposition, leading to oxidative damage. Mammals utilize distinct mechanisms to regulate iron homeostasis at the systemic and cellular levels. These involve the hormone hepcidin and iron regulatory proteins, which collectively ensure iron balance. This review outlines recent advances in iron regulatory pathways as well as in mechanisms underlying intracellular iron trafficking, an important but less studied area of mammalian iron homeostasis.
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Affiliation(s)
- Kostas Pantopoulos
- Lady Davis Institute for Medical Research, Jewish General Hospital and Department of Medicine, McGill University, Montreal, QC, Canada
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209
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Tesfay L, Huhn AJ, Hatcher H, Torti FM, Torti SV. Ferritin blocks inhibitory effects of two-chain high molecular weight kininogen (HKa) on adhesion and survival signaling in endothelial cells. PLoS One 2012; 7:e40030. [PMID: 22768328 PMCID: PMC3388046 DOI: 10.1371/journal.pone.0040030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Accepted: 06/03/2012] [Indexed: 12/16/2022] Open
Abstract
Angiogenesis is tightly regulated through complex crosstalk between pro- and anti-angiogenic signals. High molecular weight kininogen (HK) is an endogenous protein that is proteolytically cleaved in plasma and on endothelial cell surfaces to HKa, an anti-angiogenic protein. Ferritin binds to HKa and blocks its anti-angiogenic activity. Here, we explore mechanisms underlying the cytoprotective effect of ferritin in endothelial cells exposed to HKa. We observe that ferritin promotes adhesion and survival of HKa-treated cells and restores key survival and adhesion signaling pathways mediated by Erk, Akt, FAK and paxillin. We further elucidate structural motifs of both HKa and ferritin that are required for effects on endothelial cells. We identify an histidine-glycine-lysine (HGK) -rich antiproliferative region within domain 5 of HK as the target of ferritin, and demonstrate that both ferritin subunits of the H and L type regulate HKa activity. We further demonstrate that ferritin reduces binding of HKa to endothelial cells and restores the association of uPAR with α5β1 integrin. We propose that ferritin blocks the anti-angiogenic activity of HKa by reducing binding of HKa to UPAR and interfering with anti-adhesive and anti-proliferative signaling of HKa.
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Affiliation(s)
- Lia Tesfay
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Annissa J. Huhn
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Heather Hatcher
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Frank M. Torti
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
- Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Suzy V. Torti
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
- Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
- * E-mail:
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210
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Paragas N, Qiu A, Hollmen M, Nickolas TL, Devarajan P, Barasch J. NGAL-Siderocalin in kidney disease. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1451-8. [PMID: 22728330 DOI: 10.1016/j.bbamcr.2012.06.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/06/2012] [Accepted: 06/13/2012] [Indexed: 12/11/2022]
Abstract
Kidney damage induces the expression of a myriad of proteins in the serum and in the urine. The function of these proteins in the sequence of damage and repair is now being studied in genetic models and by novel imaging techniques. One of the most intensely expressed proteins is lipocalin2, also called NGAL or Siderocalin. While this protein has been best studied by clinical scientists, only a few labs study its underlying metabolism and function in tissue damage. Structure-function studies, imaging studies and clinical studies have revealed that NGAL-Siderocalin is an endogenous antimicrobial with iron scavenging activity. This review discusses the "iron problem" of kidney damage, the tight linkage between kidney damage and NGAL-Siderocalin expression and the potential roles that NGAL-Siderocalin may serve in the defense of the urogenital system. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Affiliation(s)
- Neal Paragas
- College of Physicians & Surgeons of Columbia University, New York, NY, USA
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211
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Leichtmann-Bardoogo Y, Cohen LA, Weiss A, Marohn B, Schubert S, Meinhardt A, Meyron-Holtz EG. Compartmentalization and regulation of iron metabolism proteins protect male germ cells from iron overload. Am J Physiol Endocrinol Metab 2012; 302:E1519-30. [PMID: 22496346 DOI: 10.1152/ajpendo.00007.2012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The universal importance of iron, its high toxicity, and complex chemistry present a challenge to biological systems in general and to protected compartments in particular. The high mitotic rate and avid mitochondriogenesis of developing male germ cells imply high iron requirements. Yet access to germ cells is tightly regulated by the blood-testis barrier that protects the meiotic and postmeiotic germ cells. To elucidate how iron is supplied to developing male germ cells, we analyzed iron deposition and iron transport proteins in testes of mice with iron overload and with genetic ablation of the iron regulators Hfe and iron regulatory protein 2. Iron accumulated mainly around seminiferous tubules, and only small amounts localized within the seminiferous tubules. The localization and regulation of proteins involved in iron import, storage, and export such as transferrin, transferrin receptor, the divalent metal transporter-1, cytosolic ferritin, and ferroportin strongly support a model of a largely autonomous iron cycle within seminiferous tubules. We show evidence that ferritin secretion from Sertoli cells may play an important role in iron acquisition of primary spermatocytes. During spermatogenic development iron is carried along from primary spermatocytes to spermatids, and from spermatids iron is recycled to the apical compartment of Sertoli cells, which traffic it back to a new generation of spermatocytes. Losses are replenished by the peripheral circulation. Such an internal iron cycle essentially detaches the iron homeostasis within the seminiferous tubule from the periphery and protects developing germ cells from iron fluctuations. This model explains how compartmentalization can optimize cellular and systemic nutrient homeostasis.
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212
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Feng Q, Migas MC, Waheed A, Britton RS, Fleming RE. Ferritin upregulates hepatic expression of bone morphogenetic protein 6 and hepcidin in mice. Am J Physiol Gastrointest Liver Physiol 2012; 302:G1397-404. [PMID: 22517766 PMCID: PMC3378091 DOI: 10.1152/ajpgi.00020.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepcidin is a hepatocellular hormone that inhibits the release of iron from certain cell populations, including enterocytes and reticuloendothelial cells. The regulation of hepcidin (HAMP) gene expression by iron status is mediated in part by the signaling molecule bone morphogenetic protein 6 (BMP6). We took advantage of the low iron status of juvenile mice to characterize the regulation of Bmp6 and Hamp1 expression by iron administered in three forms: 1) ferri-transferrin (Fe-Tf), 2) ferric ammonium citrate (FAC), and 3) liver ferritin. Each of these forms of iron enters cells by distinct mechanisms and chemical forms. Iron was parenterally administered to 10-day-old mice, and hepatic expression of Bmp6 and Hamp1 mRNAs was measured 6 h later. We observed that hepatic Bmp6 expression increased in response to ferritin but was unchanged by Fe-Tf or FAC. Hepatic Hamp1 expression likewise increased in response to ferritin and Fe-Tf but was decreased by FAC. Exogenous ferritin increased Bmp6 and Hamp1 expression in older mice as well. Removing iron from ferritin markedly decreased its effect on Bmp6 expression. Exogenously administered ferritin and the derived iron localized in the liver primarily to sinusoidal lining cells. Moreover, expression of Bmp6 mRNA in isolated adult rodent liver cells was much higher in sinusoidal lining cells than hepatocytes (endothelial >> stellate > Kupffer). We conclude that exogenous iron-containing ferritin upregulates hepatic Bmp6 expression, and we speculate that liver ferritin contributes to regulation of Bmp6 and, thus, Hamp1 genes.
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Affiliation(s)
- Qi Feng
- 1Department of Pediatrics, Saint Louis University School of Medicine, St. Louis, Missouri;
| | - Mary C. Migas
- 1Department of Pediatrics, Saint Louis University School of Medicine, St. Louis, Missouri;
| | - Abdul Waheed
- 3Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri
| | - Robert S. Britton
- 2Department of Internal Medicine, Saint Louis University School of Medicine, St. Louis, Missouri; and
| | - Robert E. Fleming
- 1Department of Pediatrics, Saint Louis University School of Medicine, St. Louis, Missouri; ,3Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri
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213
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Liu Y, Koyutürk M, Barnholtz-Sloan JS, Chance MR. Gene interaction enrichment and network analysis to identify dysregulated pathways and their interactions in complex diseases. BMC SYSTEMS BIOLOGY 2012; 6:65. [PMID: 22694839 PMCID: PMC3426489 DOI: 10.1186/1752-0509-6-65] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 06/13/2012] [Indexed: 01/10/2023]
Abstract
BACKGROUND The molecular behavior of biological systems can be described in terms of three fundamental components: (i) the physical entities, (ii) the interactions among these entities, and (iii) the dynamics of these entities and interactions. The mechanisms that drive complex disease can be productively viewed in the context of the perturbations of these components. One challenge in this regard is to identify the pathways altered in specific diseases. To address this challenge, Gene Set Enrichment Analysis (GSEA) and others have been developed, which focus on alterations of individual properties of the entities (such as gene expression). However, the dynamics of the interactions with respect to disease have been less well studied (i.e., properties of components ii and iii). RESULTS Here, we present a novel method called Gene Interaction Enrichment and Network Analysis (GIENA) to identify dysregulated gene interactions, i.e., pairs of genes whose relationships differ between disease and control. Four functions are defined to model the biologically relevant gene interactions of cooperation (sum of mRNA expression), competition (difference between mRNA expression), redundancy (maximum of expression), or dependency (minimum of expression) among the expression levels. The proposed framework identifies dysregulated interactions and pathways enriched in dysregulated interactions; points out interactions that are perturbed across pathways; and moreover, based on the biological annotation of each type of dysregulated interaction gives clues about the regulatory logic governing the systems level perturbation. We demonstrated the potential of GIENA using published datasets related to cancer. CONCLUSIONS We showed that GIENA identifies dysregulated pathways that are missed by traditional enrichment methods based on the individual gene properties and that use of traditional methods combined with GIENA provides coverage of the largest number of relevant pathways. In addition, using the interactions detected by GIENA, specific gene networks both within and across pathways associated with the relevant phenotypes are constructed and analyzed.
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Affiliation(s)
- Yu Liu
- Center for Proteomics & Bioinformatics, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Mehmet Koyutürk
- Center for Proteomics & Bioinformatics, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Electrical Engineering & Computer Science, Case Western Reserve University, Cleveland, OH, 44106, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Jill S Barnholtz-Sloan
- Center for Proteomics & Bioinformatics, Case Western Reserve University, Cleveland, OH, 44106, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Epidemiology and Biostatistics, Case Comprehensive Cancer Center, Cleveland, OH, 44106, USA
| | - Mark R Chance
- Center for Proteomics & Bioinformatics, Case Western Reserve University, Cleveland, OH, 44106, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Genetics, Case Western Reserve University, Cleveland, OH, 44106, USA
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214
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Geninatti Crich S, Cutrin JC, Lanzardo S, Conti L, Kálmán FK, Szabó I, Lago NR, Iolascon A, Aime S. Mn-loaded apoferritin: a highly sensitive MRI imaging probe for the detection and characterization of hepatocarcinoma lesions in a transgenic mouse model. CONTRAST MEDIA & MOLECULAR IMAGING 2012; 7:281-8. [DOI: 10.1002/cmmi.492] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | | | - Stefania Lanzardo
- Department of Clinical and Biological Sciences; University of Turin; Turin; Italy
| | - Laura Conti
- Department of Clinical and Biological Sciences; University of Turin; Turin; Italy
| | | | - Ibolya Szabó
- Center for Molecular Imaging, Department of Chemistry IFM; University of Turin; Turin; Italy
| | - Néstor R. Lago
- Center of Experimental Pathology, School of Medicine; University of Buenos Aires; Buenos Aires; Argentina
| | - Achille Iolascon
- CEINGE Biotecnologie Avanzate; University of Naples; Naples; Italy
| | - Silvio Aime
- Center for Molecular Imaging, Department of Chemistry IFM; University of Turin; Turin; Italy
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215
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Regulation of iron transport and the role of transferrin. Biochim Biophys Acta Gen Subj 2012; 1820:188-202. [DOI: 10.1016/j.bbagen.2011.10.013] [Citation(s) in RCA: 303] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2011] [Revised: 10/27/2011] [Accepted: 10/30/2011] [Indexed: 12/15/2022]
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216
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Chen C, Paw BH. Cellular and mitochondrial iron homeostasis in vertebrates. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1459-67. [PMID: 22285816 DOI: 10.1016/j.bbamcr.2012.01.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 01/07/2012] [Accepted: 01/07/2012] [Indexed: 02/08/2023]
Abstract
Iron plays an essential role in cellular metabolism and biological processes. However, due to its intrinsic redox activity, free iron is a potentially toxic molecule in cellular biochemistry. Thus, organisms have developed sophisticated ways to import, sequester, and utilize iron. The transferrin cycle is a well-studied iron uptake pathway that is important for most vertebrate cells. Circulating iron can also be imported into cells by mechanisms that are independent of transferrin. Once imported into erythroid cells, iron is predominantly consumed by the mitochondria for the biosynthesis of heme and iron sulfur clusters. This review focuses on canonical transferrin-mediated and the newly discovered, non-transferrin mediated iron uptake pathways, as well as, mitochondrial iron homeostasis in higher eukaryotes. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Affiliation(s)
- Caiyong Chen
- Department of Medicine, Hematology Division, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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217
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Kurronen A, Pihlaja R, Pollari E, Kanninen K, Storvik M, Wong G, Koistinaho M, Koistinaho J. Adult and neonatal astrocytes exhibit diverse gene expression profiles in response to beta amyloid <i>ex vivo</i>. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/wjns.2012.22009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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218
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Menssen A, Häupl T, Sittinger M, Delorme B, Charbord P, Ringe J. Differential gene expression profiling of human bone marrow-derived mesenchymal stem cells during adipogenic development. BMC Genomics 2011; 12:461. [PMID: 21943323 PMCID: PMC3222637 DOI: 10.1186/1471-2164-12-461] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Accepted: 09/24/2011] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Adipogenesis is the developmental process by which mesenchymal stem cells (MSC) differentiate into pre-adipocytes and adipocytes. The aim of the study was to analyze the developmental strategies of human bone marrow MSC developing into adipocytes over a defined time scale. Here we were particularly interested in differentially expressed transcription factors and biochemical pathways. We studied genome-wide gene expression profiling of human MSC based on an adipogenic differentiation experiment with five different time points (day 0, 1, 3, 7 and 17), which was designed and performed in reference to human fat tissue. For data processing and selection of adipogenic candidate genes, we used the online database SiPaGene for Affymetrix microarray expression data. RESULTS The mesenchymal stem cell character of human MSC cultures was proven by cell morphology, by flow cytometry analysis and by the ability of the cells to develop into the osteo-, chondro- and adipogenic lineage. Moreover we were able to detect 184 adipogenic candidate genes (85 with increased, 99 with decreased expression) that were differentially expressed during adipogenic development of MSC and/or between MSC and fat tissue in a highly significant way (p < 0.00001). Subsequently, groups of up- or down-regulated genes were formed and analyzed with biochemical and cluster tools. Among the 184 genes, we identified already known transcription factors such as PPARG, C/EBPA and RTXA. Several of the genes could be linked to corresponding biochemical pathways like the adipocyte differentiation, adipocytokine signalling, and lipogenesis pathways. We also identified new candidate genes possibly related to adipogenesis, such as SCARA5, coding for a receptor with a putative transmembrane domain and a collagen-like domain, and MRAP, encoding an endoplasmatic reticulum protein. CONCLUSIONS Comparing differential gene expression profiles of human MSC and native fat cells or tissue allowed us to establish a comprehensive differential kinetic gene expression network of adipogenesis. Based on this, we identified known and unknown genes and biochemical pathways that may be relevant for adipogenic differentiation. Our results encourage further and more focused studies on the functional relevance of particular adipogenic candidate genes.
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Affiliation(s)
- Adriane Menssen
- Tissue Engineering Laboratory, Clinic for Rheumatology and Clinical Immunology, Charité-Universitätsmedizin Berlin, Charité Platz 1, 10117 Berlin, Germany.
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219
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Martínez VG, Moestrup SK, Holmskov U, Mollenhauer J, Lozano F. The conserved scavenger receptor cysteine-rich superfamily in therapy and diagnosis. Pharmacol Rev 2011; 63:967-1000. [PMID: 21880988 DOI: 10.1124/pr.111.004523] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The scavenger receptor cysteine-rich (SRCR) superfamily of soluble or membrane-bound protein receptors is characterized by the presence of one or several repeats of an ancient and highly conserved protein module, the SRCR domain. This superfamily (SRCR-SF) has been in constant and progressive expansion, now up to more than 30 members. The study of these members is attracting growing interest, which parallels that in innate immunity. No unifying function has been described to date for the SRCR domains, this being the result of the limited knowledge still available on the physiology of most members of the SRCR-SF, but also of the sequence versatility of the SRCR domains. Indeed, involvement of SRCR-SF members in quite different functions, such as pathogen recognition, modulation of the immune response, epithelial homeostasis, stem cell biology, and tumor development, have all been described. This has brought to us new information, unveiling the possibility that targeting or supplementing SRCR-SF proteins could result in diagnostic and/or therapeutic benefit for a number of physiologic and pathologic states. Recent research has provided structural and functional insight into these proteins, facilitating the development of means to modulate the activity of SRCR-SF members. Indeed, some of these approaches are already in use, paving the way for a more comprehensive use of SRCR-SF members in the clinic. The present review will illustrate some available evidence on the potential of well known and new members of the SRCR-SF in this regard.
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Affiliation(s)
- Vanesa Gabriela Martínez
- Center Esther Koplowitz, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
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220
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Han J, Seaman WE, Di X, Wang W, Willingham M, Torti FM, Torti SV. Iron uptake mediated by binding of H-ferritin to the TIM-2 receptor in mouse cells. PLoS One 2011; 6:e23800. [PMID: 21886823 PMCID: PMC3158792 DOI: 10.1371/journal.pone.0023800] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 07/25/2011] [Indexed: 11/22/2022] Open
Abstract
Ferritin binds specifically and saturably to a variety of cell types, and recently several ferritin receptors have been cloned. TIM-2 is a specific receptor for H ferritin (HFt) in the mouse. TIM-2 is a member of the T cell immunoglobulin and mucin domain containing (TIM) protein family and plays an important role in immunity. The expression of TIM-2 outside of the immune system indicates that this receptor may have broader roles. We tested whether ferritin binding to TIM-2 can serve as an iron delivery mechanism. TIM-2 was transfected into normal (TCMK-1) mouse kidney cells, where it was appropriately expressed on the cell surface. HFt was labeled with 55Fe and 55Fe-HFt was incubated with TIM-2 positive cells or controls. 55Fe-HFt uptake was observed only in TIM-2 positive cells. HFt uptake was also seen in A20 B cells, which express endogenous TIM-2. TIM-2 levels were not increased by iron chelation. Uptake of 55Fe-HFt was specific and temperature-dependent. HFt taken up by TIM-2 positive cells transited through the endosome and eventually entered a lysosomal compartment, distinguishing the HFt pathway from that of transferrin, the classical vehicle for cellular iron delivery. Iron delivered following binding of HFt to TIM-2 entered the cytosol and became metabolically available, resulting in increased levels of endogenous intracellular ferritin. We conclude that TIM-2 can function as an iron uptake pathway.
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Affiliation(s)
- Jian Han
- Department of Biology, North Carolina Agricultural and Technical State University, Greensboro, North Carolina, United States of America
| | - William E. Seaman
- Department of Medicine, University of California San Francisco, California, United States of America
- Veterans Affairs Medical Center, San Francisco, California, United States of America
| | - Xiumin Di
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Wei Wang
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Mark Willingham
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
- Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Frank M. Torti
- Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
- Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Suzy V. Torti
- Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
- * E-mail:
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221
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Ectopic pregnancy as a model to identify endometrial genes and signaling pathways important in decidualization and regulated by local trophoblast. PLoS One 2011; 6:e23595. [PMID: 21858178 PMCID: PMC3157392 DOI: 10.1371/journal.pone.0023595] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 07/20/2011] [Indexed: 11/19/2022] Open
Abstract
The endometrium in early pregnancy undergoes decidualization and functional changes induced by local trophoblast, which are not fully understood. We hypothesized that endometrium from tubal ectopic pregnancy (EP) could be interrogated to identify novel genes and pathways involved in these processes. Gestation-matched endometrium was collected from women with EP (n = 11) and intrauterine pregnancies (IUP) (n = 13). RNA was extracted from the tissue. In addition, tissues were prepared for histological analysis for degree of decidualization. We compared a) the samples from EP that were decidualized (n = 6) with non-decidualized samples (n = 5), and b) the decidualized EP (n = 6) with decidualization-matched IUP (n = 6) samples using an Affymetrix gene array platform, with Ingenuity Pathway Analysis, combined with quantitative RT-PCR. Expression of PRL and IGFBP1 was used to confirm the degree of decidualization in each group. There were no differences in PRL or IGFBP1 expression in the decidualization-matched samples but a marked reduction (P<0.001) in the non-decidualized samples. Decidualization was associated with increased expression of 428 genes including SCARA5 (181-fold), DKK1 (71-fold) and PROK1 (32-fold), and decreased expression of 230 genes including MMP-7 (35-fold) and SFRP4 (21-fold). The top canonical pathways associated with these differentially expressed genes were Natural Killer Cell and Wnt/b-Catenin signaling. Local trophoblast was associated with much less alteration of endometrial gene expression with an increase in 56 genes, including CSH1 (8-fold), and a reduction in 29 genes including CRISP3 (8-fold). The top associated canonical pathway was Antigen Presentation. The study of endometrium from tubal EP may promote novel insights into genes involved in decidualization and those influenced by factors from neighboring trophoblast. This has afforded unique information not highlighted by previous studies and adds to our understanding of the endometrium in early pregnancy.
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222
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Brissot P, Ropert M, Le Lan C, Loréal O. Non-transferrin bound iron: a key role in iron overload and iron toxicity. Biochim Biophys Acta Gen Subj 2011; 1820:403-10. [PMID: 21855608 DOI: 10.1016/j.bbagen.2011.07.014] [Citation(s) in RCA: 448] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 07/21/2011] [Accepted: 07/28/2011] [Indexed: 12/12/2022]
Abstract
BACKGROUND Besides transferrin iron, which represents the normal form of circulating iron, non-transferrin bound iron (NTBI) has been identified in the plasma of patients with various pathological conditions in which transferrin saturation is significantly elevated. SCOPE OF THE REVIEW To show that: i) NTBI is present not only during chronic iron overload disorders (hemochromatosis, transfusional iron overload) but also in miscellaneous diseases which are not primarily iron overloaded conditions; ii) this iron species represents a potentially toxic iron form due to its high propensity to induce reactive oxygen species and is responsible for cellular damage not only at the plasma membrane level but also towards different intracellular organelles; iii) the NTBI concept may be expanded to include intracytosolic iron forms which are not linked to ferritin, the major storage protein which exerts, at the cellular level, the same type of protective effect towards the intracellular environment as transferrin in the plasma. MAJOR CONCLUSIONS Plasma NTBI and especially labile plasma iron determinations represent a new important biological tool since elimination of this toxic iron species is a major therapeutic goal. GENERAL SIGNIFICANCE The NTBI approach represents an important mechanistic concept for explaining cellular iron excess and toxicity and provides new important biochemical diagnostic tools. This article is part of a Special Issue entitled Transferrins: Molecular mechanisms of iron transport and disorders.
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Affiliation(s)
- Pierre Brissot
- Inserm, UMR991, Liver Metabolisms and Cancer, F-35033 Rennes, France.
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223
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Mechanisms of brain iron transport: insight into neurodegeneration and CNS disorders. Future Med Chem 2011; 2:51-64. [PMID: 20161623 DOI: 10.4155/fmc.09.140] [Citation(s) in RCA: 206] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Trace metals such as iron, copper, zinc, manganese, and cobalt are essential cofactors for many cellular enzymes. Extensive research on iron, the most abundant transition metal in biology, has contributed to an increased understanding of the molecular machinery involved in maintaining its homeostasis in mammalian peripheral tissues. However, the cellular and intercellular iron transport mechanisms in the central nervous system (CNS) are still poorly understood. Accumulating evidence suggests that impaired iron metabolism is an initial cause of neurodegeneration, and several common genetic and sporadic neurodegenerative disorders have been proposed to be associated with dysregulated CNS iron homeostasis. This review aims to provide a summary of the molecular mechanisms of brain iron transport. Our discussion is focused on iron transport across endothelial cells of the blood-brain barrier and within the neuro- and glial-vascular units of the brain, with the aim of revealing novel therapeutic targets for neurodegenerative and CNS disorders.
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224
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Kurz T, Gustafsson B, Brunk UT. Cell sensitivity to oxidative stress is influenced by ferritin autophagy. Free Radic Biol Med 2011; 50:1647-58. [PMID: 21419217 DOI: 10.1016/j.freeradbiomed.2011.03.014] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 02/24/2011] [Accepted: 03/08/2011] [Indexed: 12/19/2022]
Abstract
To test the consequences of lysosomal degradation of differently iron-loaded ferritin molecules and to mimic ferritin autophagy under iron-overload and normal conditions, J774 cells were allowed to endocytose heavily iron loaded ferritin, probably with some adventitious iron (Fe-Ft), or iron-free apo-ferritin (apo-Ft). When cells subsequently were exposed to a bolus dose of hydrogen peroxide, apo-Ft prevented lysosomal membrane permeabilization (LMP), whereas Fe-Ft enhanced LMP. A 4-h pulse of Fe-Ft initially increased oxidative stress-mediated LMP that was reversed after another 3h under standard culture conditions, suggesting that lysosomal iron is rapidly exported from lysosomes, with resulting upregulation of apo-ferritin that supposedly is autophagocytosed, thereby preventing LMP by binding intralysosomal redox-active iron. The obtained data suggest that upregulation of the stress protein ferritin is a rapid adaptive mechanism that counteracts LMP and ensuing apoptosis during oxidative stress. In addition, prolonged iron starvation was found to induce apoptotic cell death that, interestingly, was preceded by LMP, suggesting that LMP is a more general phenomenon in apoptosis than so far recognized. The findings provide new insights into aging and neurodegenerative diseases that are associated with enhanced amounts of cellular iron and show that lysosomal iron loading sensitizes to oxidative stress.
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Affiliation(s)
- Tino Kurz
- Division of Pharmacology, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
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225
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Sun C, Yang H, Yuan Y, Tian X, Wang L, Guo Y, Xu L, Lei J, Gao N, Anderson GJ, Liang XJ, Chen C, Zhao Y, Nie G. Controlling Assembly of Paired Gold Clusters within Apoferritin Nanoreactor for in Vivo Kidney Targeting and Biomedical Imaging. J Am Chem Soc 2011; 133:8617-24. [DOI: 10.1021/ja200746p] [Citation(s) in RCA: 233] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Cuiji Sun
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
- Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, Jilin University, Changchun, China
| | - Hui Yang
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Yi Yuan
- MOE Key Laboratory of Bioinformatics, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Xin Tian
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Liming Wang
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Yi Guo
- Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, Jilin University, Changchun, China
| | - Li Xu
- Key Laboratory for Molecular Enzymology and Engineering, the Ministry of Education, Jilin University, Changchun, China
| | - Jianlin Lei
- MOE Key Laboratory of Bioinformatics, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Ning Gao
- MOE Key Laboratory of Bioinformatics, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Gregory J. Anderson
- Iron Metabolism Laboratory, Queensland Institute of Medical Research, Royal Brisbane Hospital, Brisbane, Queensland 4029, Australia
| | - Xing-Jie Liang
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Chunying Chen
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Yuliang Zhao
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
| | - Guangjun Nie
- CAS Key Laboratory for Biological Effects of Nanomaterials & Nanosafety, National Center for Nanoscience and Technology, Beijing 100190, China
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226
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Abstract
Iron is an essential but potentially hazardous biometal. Mammalian cells require sufficient amounts of iron to satisfy metabolic needs or to accomplish specialized functions. Iron is delivered to tissues by circulating transferrin, a transporter that captures iron released into the plasma mainly from intestinal enterocytes or reticuloendothelial macrophages. The binding of iron-laden transferrin to the cell-surface transferrin receptor 1 results in endocytosis and uptake of the metal cargo. Internalized iron is transported to mitochondria for the synthesis of haem or iron–sulfur clusters, which are integral parts of several metalloproteins, and excess iron is stored and detoxified in cytosolic ferritin. Iron metabolism is controlled at different levels and by diverse mechanisms. The present review summarizes basic concepts of iron transport, use and storage and focuses on the IRE (iron-responsive element)/IRP (iron-regulatory protein) system, a well known post-transcriptional regulatory circuit that not only maintains iron homoeostasis in various cell types, but also contributes to systemic iron balance.
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227
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A possible role for secreted ferritin in tissue iron distribution. J Neural Transm (Vienna) 2011; 118:337-47. [PMID: 21298454 DOI: 10.1007/s00702-011-0582-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 01/09/2011] [Indexed: 01/19/2023]
Abstract
Ferritin is known as a well-conserved iron detoxification and storage protein that is found in the cytosol of many prokaryotic and eukaryotic organisms. In insects and worms, ferritin has evolved into a classically secreted protein that transports iron systemically. Mammalian ferritins are found intracellularly in the cytosol, as well as in the nucleus, the endo-lysosomal compartment and the mitochondria. Extracellular ferritin is found in fluids such as serum and synovial and cerebrospinal fluids. We recently characterized the biophysical properties, secretion mechanism and cellular origin of mouse serum ferritin, which is actively secreted by a non-classical pathway involving lysosomal processing. Here, we review the data to support a hypothesis that intracellular and extracellular ferritin may play a role in intra- and intercellular redistribution of iron.
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228
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The many faces of the octahedral ferritin protein. Biometals 2011; 24:489-500. [PMID: 21267633 DOI: 10.1007/s10534-011-9415-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 01/13/2011] [Indexed: 12/14/2022]
Abstract
Iron is an essential trace nutrient required for the active sites of many enzymes, electron transfer and oxygen transport proteins. In contrast, to its important biological roles, iron is a catalyst for reactive oxygen species (ROS). Organisms must acquire iron but must protect against oxidative damage. Biology has evolved siderophores, hormones, membrane transporters, and iron transport and storage proteins to acquire sufficient iron but maintain iron levels at safe concentrations that prevent iron from catalyzing the formation of ROS. Ferritin is an important hub for iron metabolism because it sequesters iron during times of iron excess and releases iron during iron paucity. Ferritin is expressed in response to oxidative stress and is secreted into the extracellular matrix and into the serum. The iron sequestering ability of ferritin is believed to be the source of the anti-oxidant properties of ferritin. In fact, ferritin has been used as a biomarker for disease because it is synthesized in response to oxidative damage and inflammation. The function of serum ferritin is poorly understood, however serum ferritin concentrations seem to correlate with total iron stores. Under certain conditions, ferritin is also associated with pro-oxidant activity. The source of this switch from anti-oxidant to pro-oxidant has not been established but may be associated with unregulated iron release from ferritin. Recent reports demonstrate that ferritin is involved in other aspects of biology such as cell activation, development, immunity and angiogenesis. This review examines ferritin expression and secretion in correlation with anti-oxidant activity and with respect to these new functions. In addition, conditions that lead to pro-oxidant conditions are considered.
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229
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Sultana R, Di Domenico F, Tseng M, Cai J, Noel T, Chelvarajan RL, Pierce WD, Cini C, Bondada S, St. Clair DK, Butterfield DA. Doxorubicin-Induced Thymus Senescence. J Proteome Res 2010; 9:6232-41. [DOI: 10.1021/pr100465m] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Rukhsana Sultana
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - Fabio Di Domenico
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - Michael Tseng
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - Jian Cai
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - Teresa Noel
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - R. Lakshman Chelvarajan
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - William D. Pierce
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - Ciara Cini
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - Subbarao Bondada
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - Daret K. St. Clair
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
| | - D. Allan Butterfield
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States, Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy, Department of Anatomical Sciences & Neurobiology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Pharmacology, University of Louisville, Louisville, Kentucky 40202, United States, Department of Toxicology, University of Kentucky, Lexington, Kentucky 40536, United States, Department of Microbiology
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230
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Hentze MW, Muckenthaler MU, Galy B, Camaschella C. Two to tango: regulation of Mammalian iron metabolism. Cell 2010; 142:24-38. [PMID: 20603012 DOI: 10.1016/j.cell.2010.06.028] [Citation(s) in RCA: 1429] [Impact Index Per Article: 102.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2010] [Revised: 06/14/2010] [Accepted: 06/21/2010] [Indexed: 02/06/2023]
Abstract
Disruptions in iron homeostasis from both iron deficiency and overload account for some of the most common human diseases. Iron metabolism is balanced by two regulatory systems, one that functions systemically and relies on the hormone hepcidin and the iron exporter ferroportin, and another that predominantly controls cellular iron metabolism through iron-regulatory proteins that bind iron-responsive elements in regulated messenger RNAs. We describe how the two distinct systems function and how they "tango" together in a coordinated manner. We also highlight some of the current questions in mammalian iron metabolism and discuss therapeutic opportunities arising from a better understanding of the underlying biological principles.
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Affiliation(s)
- Matthias W Hentze
- European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
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231
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Wang W, Knovich MA, Coffman LG, Torti FM, Torti SV. Serum ferritin: Past, present and future. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1800:760-9. [PMID: 20304033 PMCID: PMC2893236 DOI: 10.1016/j.bbagen.2010.03.011] [Citation(s) in RCA: 514] [Impact Index Per Article: 36.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Revised: 03/11/2010] [Accepted: 03/13/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND Serum ferritin was discovered in the 1930s, and was developed as a clinical test in the 1970s. Many diseases are associated with iron overload or iron deficiency. Serum ferritin is widely used in diagnosing and monitoring these diseases. SCOPE OF REVIEW In this chapter, we discuss the role of serum ferritin in physiological and pathological processes and its use as a clinical tool. MAJOR CONCLUSIONS Although many aspects of the fundamental biology of serum ferritin remain surprisingly unclear, a growing number of roles have been attributed to extracellular ferritin, including newly described roles in iron delivery, angiogenesis, inflammation, immunity, signaling and cancer. GENERAL SIGNIFICANCE Serum ferritin remains a clinically useful tool. Further studies on the biology of this protein may provide new biological insights.
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Affiliation(s)
- Wei Wang
- Department of Cancer Biology, Wake Forest University School of Medicine, Winston Salem, NC 27157, USA
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232
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Li S. Identification of iron-loaded ferritin as an essential mitogen for cell proliferation and postembryonic development in Drosophila. Cell Res 2010; 20:1148-57. [DOI: 10.1038/cr.2010.102] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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233
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Gnana-Prakasam JP, Martin PM, Smith SB, Ganapathy V. Expression and function of iron-regulatory proteins in retina. IUBMB Life 2010; 62:363-70. [PMID: 20408179 DOI: 10.1002/iub.326] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Iron is essential for cell survival and function; yet excess iron is toxic to cells. Therefore, the cellular and whole-body levels of iron are regulated exquisitely. At least a dozen proteins participate in the regulation of iron homeostasis. Hemochromatosis, a genetic disorder of iron overload, is caused by mutations in at least five genes, namely HFE, hemojuvelin, Transferrin receptor 2, ferroportin, and hepcidin. Retina is separated from systemic circulation by inner and outer blood-retinal barriers; therefore it is widely believed that this tissue is immune to changes in systemic circulation. Even though hemochromatosis is associated with iron overload and dysfunction of a variety of systemic organs, little is known on the effects of this disease on the retina. Recent studies have shown that all five genes that are associated with hemochromatosis are expressed in the retina in a cell type-specific manner. The retinal pigment epithelium, which forms the outer blood-retinal barrier, expresses all of these five genes. It is therefore clearly evident that iron homeostasis in the retina is maintained locally by active participation of various iron-regulatory proteins. Excess iron is detrimental to the retina as evidenced from human studies and from mouse models of iron overload. Retinal iron homeostasis is disrupted in various clinical conditions such as hemochromatosis, aceruloplasminemia, age-related macular degeneration, and bacterial and viral infections.
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Affiliation(s)
- Jaya P Gnana-Prakasam
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta, GA, USA
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234
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Iron traffics in circulation bound to a siderocalin (Ngal)-catechol complex. Nat Chem Biol 2010; 6:602-9. [PMID: 20581821 PMCID: PMC2907470 DOI: 10.1038/nchembio.402] [Citation(s) in RCA: 244] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 05/27/2010] [Indexed: 02/06/2023]
Abstract
The lipocalins are secreted proteins that bind small organic molecules. Scn-Ngal (also known as neutrophil gelatinase associated lipocalin, siderocalin, lipocalin 2) sequesters bacterial iron chelators, called siderophores, and consequently blocks bacterial growth. However, Scn-Ngal is also prominently expressed in aseptic diseases, implying that it binds additional ligands and serves additional functions. Using chemical screens, crystallography and fluorescence methods, we report that Scn-Ngal binds iron together with a small metabolic product called catechol. The formation of the complex blocked the reactivity of iron and permitted its transport once introduced into circulation in vivo. Scn-Ngal then recycled its iron in endosomes by a pH-sensitive mechanism. As catechols derive from bacterial and mammalian metabolism of dietary compounds, the Scn-Ngal-catechol-Fe(III) complex represents an unforeseen microbial-host interaction, which mimics Scn-Ngal-siderophore interactions but instead traffics iron in aseptic tissues. These results identify an endogenous siderophore, which may link the disparate roles of Scn-Ngal in different diseases.
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235
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Abstract
Recent advances in research on iron metabolism have revealed the identity of a number of genes, signal transduction pathways, and proteins involved in iron regulation in mammals. The emerging paradigm is a coordination of homeostasis within a network of classical iron metabolic pathways and other cellular processes such as cell differentiation, growth, inflammation, immunity, and a host of physiologic and pathologic conditions. Iron, immunity, and infection are intricately linked and their regulation is fundamental to the survival of mammals. The mutual dependence on iron by the host and invading pathogenic organisms elicits competition for the element during infection. While the host maintains mechanisms to utilize iron for its own metabolism exclusively, pathogenic organisms are armed with a myriad of strategies to circumvent these measures. This review explores iron metabolism in mammalian host, defense mechanisms against pathogenic microbes and the competitive devices of microbes for access to iron.
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Affiliation(s)
- Gladys O Latunde-Dada
- King's College London, Nutritional Sciences Division, School of Biomedical and Health Sciences, Franklin-Wilkins Building, London SE1 9NH, United Kingdom.
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236
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Serum ferritin is derived primarily from macrophages through a nonclassical secretory pathway. Blood 2010; 116:1574-84. [PMID: 20472835 DOI: 10.1182/blood-2009-11-253815] [Citation(s) in RCA: 305] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The serum ferritin concentration is a clinical parameter measured widely for the differential diagnosis of anemia. Its levels increase with elevations of tissue iron stores and with inflammation, but studies on cellular sources of serum ferritin as well as its subunit composition, degree of iron loading and glycosylation have given rise to conflicting results. To gain further understanding of serum ferritin, we have used traditional and modern methodologies to characterize mouse serum ferritin. We find that both splenic macrophages and proximal tubule cells of the kidney are possible cellular sources for serum ferritin and that serum ferritin is secreted by cells rather than being the product of a cytosolic leak from damaged cells. Mouse serum ferritin is composed mostly of L-subunits, whereas it contains few H-subunits and iron content is low. L-subunits of serum ferritin are frequently truncated at the C-terminus, giving rise to a characteristic 17-kD band that has been previously observed in lysosomal ferritin. Taken together with the fact that mouse serum ferritin is not detectably glycosylated, we propose that mouse serum ferritin is secreted through the nonclassical lysosomal secretory pathway.
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237
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Binding and uptake of H-ferritin are mediated by human transferrin receptor-1. Proc Natl Acad Sci U S A 2010; 107:3505-10. [PMID: 20133674 DOI: 10.1073/pnas.0913192107] [Citation(s) in RCA: 360] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ferritin is a spherical molecule composed of 24 subunits of two types, ferritin H chain (FHC) and ferritin L chain (FLC). Ferritin stores iron within cells, but it also circulates and binds specifically and saturably to a variety of cell types. For most cell types, this binding can be mediated by ferritin composed only of FHC (HFt) but not by ferritin composed only of FLC (LFt), indicating that binding of ferritin to cells is mediated by FHC but not FLC. By using expression cloning, we identified human transferrin receptor-1 (TfR1) as an important receptor for HFt with little or no binding to LFt. In vitro, HFt can be precipitated by soluble TfR1, showing that this interaction is not dependent on other proteins. Binding of HFt to TfR1 is partially inhibited by diferric transferrin, but it is hindered little, if at all, by HFE. After binding of HFt to TfR1 on the cell surface, HFt enters both endosomes and lysosomes. TfR1 accounts for most, if not all, of the binding of HFt to mitogen-activated T and B cells, circulating reticulocytes, and all cell lines that we have studied. The demonstration that TfR1 can bind HFt as well as Tf raises the possibility that this dual receptor function may coordinate the processing and use of iron by these iron-binding molecules.
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238
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Hansen SL, Trakooljul N, Spears JW, Liu HC. Age and dietary iron affect expression of genes involved in iron acquisition and homeostasis in young pigs. J Nutr 2010; 140:271-7. [PMID: 20018808 DOI: 10.3945/jn.109.112722] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
To investigate the effects of dietary iron (Fe) and age on Fe metabolism, we used 36 weaned barrows in a 2 x 3 design with 2 concentrations of dietary Fe [97 (control) and 797 (high Fe) mg Fe/kg dry matter] and 3 time points of tissue collection (after 21, 42, or 63 d on diets). Pigs were weighed and bled on d 0, 20, 41, and 62. High Fe reduced feed efficiency but did not affect pig weight gain. Blood hemoglobin concentrations and Fe concentrations of liver, intestine, and heart were increased by high dietary Fe on all days. Concentrations of liver and heart Fe increased with age. As determined by quantitative real-time PCR, hepatic expression of hepcidin (HAMP) in pigs given the high-Fe diet was 6.25-fold that of control pigs. In the intestine, relative mRNA levels of ferroportin, divalent metal transporter 1, and transferrin receptor were downregulated by high Fe. Expression of an alternative route of Fe absorption, solute carrier family 39 member 14 (SLC39A14), was downregulated in the intestine of pigs fed high dietary Fe. Additionally, duodenal mRNA level of certain genes including scavenger receptor class A, member 5, and frataxin decreased with age of the animal. Our findings indicate new roles in Fe metabolism for several mineral metabolism-associated genes and that some of these genes, such as SLC39A14, may be regulated in response to dietary Fe in pigs. Additionally, the expression of some genes examined in this study was affected by age, suggesting age dependency of Fe metabolism in pigs.
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Affiliation(s)
- Stephanie L Hansen
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695-7621, USA
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239
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Anderson GJ, Vulpe CD. Mammalian iron transport. Cell Mol Life Sci 2009; 66:3241-61. [PMID: 19484405 PMCID: PMC11115736 DOI: 10.1007/s00018-009-0051-1] [Citation(s) in RCA: 221] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2009] [Revised: 04/21/2009] [Accepted: 05/12/2009] [Indexed: 02/07/2023]
Abstract
Iron is essential for basic cellular processes but is toxic when present in excess. Consequently, iron transport into and out of cells is tightly regulated. Most iron is delivered to cells bound to plasma transferrin via a process that involves transferrin receptor 1, divalent metal-ion transporter 1 and several other proteins. Non-transferrin-bound iron can also be taken up efficiently by cells, although the mechanism is poorly understood. Cells can divest themselves of iron via the iron export protein ferroportin in conjunction with an iron oxidase. The linking of an oxidoreductase to a membrane permease is a common theme in membrane iron transport. At the systemic level, iron transport is regulated by the liver-derived peptide hepcidin which acts on ferroportin to control iron release to the plasma.
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Affiliation(s)
- Gregory Jon Anderson
- Iron Metabolism Laboratory, Queensland Institute of Medical Research, PO Royal Brisbane Hospital, QLD, Australia.
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240
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241
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Garrick MD, Garrick LM. Cellular iron transport. Biochim Biophys Acta Gen Subj 2009; 1790:309-25. [DOI: 10.1016/j.bbagen.2009.03.018] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2008] [Revised: 03/23/2009] [Accepted: 03/23/2009] [Indexed: 01/24/2023]
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242
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Expression of the iron-regulatory protein haemojuvelin in retina and its regulation during cytomegalovirus infection. Biochem J 2009; 419:533-43. [PMID: 19191760 DOI: 10.1042/bj20082240] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Haemochromatosis is a genetic disorder of iron overload resulting from loss-of-function mutations in genes coding for the iron-regulatory proteins HFE [HLA-like protein involved in iron (Fe) homoeostasis], transferrin receptor 2, ferroportin, hepcidin and HJV (haemojuvelin). Expression of the first four genes coding for these proteins in retina has been established. Here we report on the expression of HJV. Since infection of retina with CMV (cytomegalovirus) causes blindness, we also investigated the expression of HJV and other iron-regulatory proteins in retina during CMV infection. HJV (HJV gene) mRNA was expressed in RPE (retinal pigment epithelium)/eyecup and neural retina in mouse. In situ hybridization and immunohistochemistry confirmed the presence of HJV mRNA and protein in RPE, outer and inner nuclear layers, and ganglion cell layer. Immunocytochemistry with cell lines and primary cell cultures showed HJV expression in RPE and Müller cells. In RPE, the expression was restricted to apical membrane. Infection of primary cultures of mouse RPE with CMV increased HJV mRNA and protein levels. Under similar conditions, HFE (HFE gene) mRNA levels were not altered, but HFE protein was decreased. Hepcidin expression was, however, not altered. These findings were demonstrable in vivo with CMV-infected mouse retina. The CMV-induced up-regulation of HJV in RPE was independent of changes in HFE because the phenomenon was also seen in HFE-null RPE cells. CMV-infected primary RPE cells showed evidence of iron accumulation and oxidative stress, as indicated by increased levels of ferritin and hydroxynonenal. The observed changes in HJV expression and iron status during CMV infection in retina may have significance in the pathophysiology of CMV retinitis.
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243
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Troadec MB, Ward DM, Kaplan J. A Tf-independent iron transport system required for organogenesis. Dev Cell 2009; 16:3-4. [PMID: 19154711 DOI: 10.1016/j.devcel.2008.12.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Cells require iron as a cofactor for proteins that are essential for growth. While delivery of iron to cells by transferrin is well known, Li et al. in this issue of Developmental Cell show that ferritin, through its binding to the cell surface Scara5 receptor, can also deliver iron to cells, permitting kidney organogenesis.
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Affiliation(s)
- Marie-Berengere Troadec
- Department of Pathology, School of Medicine, University of Utah, Salt Lake City, UT 84132, USA
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244
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Serum ferritin regulates blood vessel formation: a role beyond iron storage. Proc Natl Acad Sci U S A 2009; 106:1683-4. [PMID: 19193849 DOI: 10.1073/pnas.0813318106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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