Ferroportin

Solute carrier family 40 (iron-regulated transporter), member 1
Identifiers
Symbols	SLC40A1 ; FPN1; HFE4; IREG1; MST079; MSTP079; MTP1; SLC11A3
External IDs	OMIM: 604653 MGI: 1315204 HomoloGene: 40959 GeneCards: SLC40A1 Gene
Gene ontology Molecular function • receptor activity • iron ion transmembrane transporter activity • protein binding • ferrous iron transmembrane transporter activity • peptide hormone binding • iron channel activity Cellular component • intracellular • cytoplasm • multivesicular body • plasma membrane • integral component of plasma membrane • synaptic vesicle • integral component of membrane • basolateral plasma membrane Biological process • lymphocyte homeostasis • endothelium development • cellular iron ion homeostasis • anatomical structure morphogenesis • regulation of transcription from RNA polymerase II promoter in response to iron • iron ion transmembrane transport • negative regulation of apoptotic process • positive regulation of transcription from RNA polymerase II promoter • transmembrane transport • spleen trabecula formation • multicellular organismal iron ion homeostasis • ferrous iron export Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	30061	53945
Ensembl	ENSG00000138449	ENSMUSG00000025993
UniProt	Q9NP59	Q9JHI9
RefSeq (mRNA)	NM_014585	NM_016917
RefSeq (protein)	NP_055400	NP_058613
Location (UCSC)	Chr 2: 189.56 – 189.58 Mb	Chr 1: 45.91 – 45.93 Mb
PubMed search

Ferroportin-1 also known as solute carrier family 40 member 1 (SLC40A1) or iron-regulated transporter 1 is a protein that in humans is encoded by the SLC40A1 gene.^[1] Ferroportin is a transmembrane protein that transports iron from the inside of a cell to the outside of the cell.

Structure

Ferroportin-1 consists of 571 amino acid residues,^[2] with a highly conserved histidine at residue position 32. When mutated, lower activity in its iron transport role is observed.^[3]

Tissue distribution

Ferroportin is found on the surface of cells that store or transport iron, including:^[4]

• Enterocytes in the duodenum
• Hepatocytes
• Macrophages of the reticuloendothelial system.
• Adipocytes

Role in development

Ferroportin-1 plays an important role in neural tube closure and forebrain patterning.^[5]

Mouse embyros lacking the Scl40a1 gene are aborted before gastrulation occurs, proving that the Fpn1 protein encoded is necessary and essential for normal embryonic development.^[4] Fpn1 is expressed in the syncytiotrophoblast cells in the placenta and visceral endoderm of mice at E7.5.^[1][4] Further, several retrospective studies have noted an increased incidence of spina bifida occurring after low maternal intake of iron during embryonic and fetal development.^[6][7]

A recent study examining the consequences of several different mutations of the Slc40a1 mouse gene concluded that several serious neural tube and patterning defects were produced as a result, including spina bifida, exencephaly, and forebrain truncations, among others.^[5] Given the findings of studies to date, there appears to be significant evidence that intact iron transport mechanisms are critical to normal neural tube closure. Furthermore, other experiments have suggested that Fpn1 product and activity is required along the entire anterior-posterior axis of the animal to ensure proper closure of the neural tube.^[5]

Role in iron metabolism

Ferroportin is inhibited by hepcidin, which binds to ferroportin and internalises it within the cell.^[8] This results in the retention of iron within enterocytes, hepatocytes, and macrophages with a consequent reduction in iron levels within the blood serum. This is especially significant with enterocytes which, when shed at the end of their lifespan, results in significant iron loss.

This is part of the mechanism that causes anaemia of chronic disease; hepcidin is released from the liver in response to inflammatory cytokines, namely interleukin-6, which results in an increased hepcidin concentration and a consequent decrease in plasma iron levels.^[9]

The ferroportin expression is also regulated by the IRP regulatory mechanism. If the iron concentration is too low, the IRP concentration increases, thus inhibiting the ferroportin translation. The ferroportin translation is also regulated by the micro RNA miR-485-3p.

Clinical significance

Mutations in the ferroportin gene are known to cause an autosomal dominant form of iron overload known as Type IV Haemochromatosis or Ferroportin Disease. The effects of the mutations are generally not severe but a spectrum of clinical outcomes are seen with different mutations. Ferroportin is also associated with African iron overload. Ferroportin and hepcidin are critical proteins for the regulation of systemic iron homeostasis. Both ferroportin and hepcidin are expressed in cultured human breast epithelial cells and hepcidin regulates ferroportin in these cells. Transfection of breast cancer cells with ferroportin significantly reduces their growth after orthotopic implantation in the mouse mammary fat pad. Ferroportin is a pivotal protein in breast biology and a strong and independent predictor of prognosis in breast cancer.^[10]

References

1. Donovan A, Brownlie A, Zhou Y, Shepard J, Pratt SJ, Moynihan J, Paw BH, Drejer A, Barut B, Zapata A, Law TC, Brugnara C, Lux SE, Pinkus GS, Pinkus JL, Kingsley PD, Palis J, Fleming MD, Andrews NC, Zon LI (February 2000). "Positional cloning of zebrafish ferroportin1 identifies a conserved vertebrate iron exporter". Nature 403 (6771): 776–81. doi:10.1038/35001596. PMID 10693807.
2. "SLC11A3 iron transporter [Homo sapiens]". Protein - NCBI.
3. Zohn IE, De Domenico I, Pollock A, Ward DM, Goodman JF, Liang X, Sanchez AJ, Niswander L, Kaplan J (May 2007). "The flatiron mutation in mouse ferroportin acts as a dominant negative to cause ferroportin disease". Blood 109 (10): 4174–80. doi:10.1182/blood-2007-01-066068. PMC 1885502. PMID 17289807.
4. Donovan A, Lima CA, Pinkus JL, Pinkus GS, Zon LI, Robine S, Andrews NC (March 2005). "The iron exporter ferroportin/Slc40a1 is essential for iron homeostasis". Cell Metab. 1 (3): 191–200. doi:10.1016/j.cmet.2005.01.003. PMID 16054062.
5. Mao J, McKean DM, Warrier S, Corbin JG, Niswander L, Zohn IE (September 2010). "The iron exporter ferroportin 1 is essential for development of the mouse embryo, forebrain patterning and neural tube closure". Development 137 (18): 3079–88. doi:10.1242/dev.048744. PMC 2926957. PMID 20702562.
6. Felkner MM, Suarez L, Brender J, Scaife B, Hendricks K (December 2005). "Iron status indicators in women with prior neural tube defect-affected pregnancies". Matern Child Health J 9 (4): 421–8. doi:10.1007/s10995-005-0017-3. PMID 16315101.
7. Groenen PM, van Rooij IA, Peer PG, Ocké MC, Zielhuis GA, Steegers-Theunissen RP (June 2004). "Low maternal dietary intakes of iron, magnesium, and niacin are associated with spina bifida in the offspring". J. Nutr. 134 (6): 1516–22. PMID 15173422.
8. Nemeth E, Tuttle MS, Powelson J, Vaughn MB, Donovan A, Ward DM, Ganz T, Kaplan J (December 2004). "Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization". Science 306 (5704): 2090–3. doi:10.1126/science.1104742. PMID 15514116.
9. Nemeth E, Rivera S, Gabayan V, Keller C, Taudorf S, Pedersen BK, Ganz T (May 2004). "IL-6 mediates hypoferremia of inflammation by inducing the synthesis of the iron regulatory hormone hepcidin". J. Clin. Invest. 113 (9): 1271–6. doi:10.1172/JCI20945. PMC 398432. PMID 15124018.
10. Pinnix ZK, Miller LD, Wang W, D'Agostino R Jr, Kute T, Willingham MC, Hatcher H, Tesfay L, Sui G, Di X, Torti SV, Torti FM (2010). "Ferroportin and Iron Regulation in Breast Cancer Progression and Prognosis". Science Translational Medicine 2 (43): 43ra56. doi:10.1126/scitranslmed.3001127. PMID 20686179.

Further reading

• Schimanski LM, Drakesmith H, Merryweather-Clarke AT, Viprakasit V, Edwards JP, Sweetland E, Bastin JM, Cowley D, Chinthammitr Y, Robson KJ, Townsend AR (May 2005). "In vitro functional analysis of human ferroportin (FPN) and hemochromatosis-associated FPN mutations". Blood 105 (10): 4096–102. doi:10.1182/blood-2004-11-4502. PMID 15692071.
• Pietrangelo A (2004). "The ferroportin disease". Blood Cells Mol. Dis. 32 (1): 131–8. doi:10.1016/j.bcmd.2003.08.003. PMID 14757427.
• Robson KJ, Merryweather-Clarke AT, Cadet E, Viprakasit V, Zaahl MG, Pointon JJ, Weatherall DJ, Rochette J (October 2004). "Recent advances in understanding haemochromatosis: a transition state". J. Med. Genet. 41 (10): 721–30. doi:10.1136/jmg.2004.020644. PMC 1735598. PMID 15466004.
• Maruyama K, Sugano S (January 1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides". Gene 138 (1-2): 171–4. doi:10.1016/0378-1119(94)90802-8. PMID 8125298.
• Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, Suyama A, Sugano S (October 1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library". Gene 200 (1-2): 149–56. doi:10.1016/S0378-1119(97)00411-3. PMID 9373149.
• Abboud S, Haile DJ (June 2000). "A novel mammalian iron-regulated protein involved in intracellular iron metabolism". J. Biol. Chem. 275 (26): 19906–12. doi:10.1074/jbc.M000713200. PMID 10747949.
• Haile DJ (2000). "Assignment of Slc11a3 to mouse chromosome 1 band 1B and SLC11A3 to human chromosome 2q32 by in situ hybridization". Cytogenet. Cell Genet. 88 (3-4): 328–9. doi:10.1159/000015522. PMID 10828623.
• McKie AT, Marciani P, Rolfs A, Brennan K, Wehr K, Barrow D, Miret S, Bomford A, Peters TJ, Farzaneh F, Hediger MA, Hentze MW, Simpson RJ (February 2000). "A novel duodenal iron-regulated transporter, IREG1, implicated in the basolateral transfer of iron to the circulation". Mol. Cell 5 (2): 299–309. doi:10.1016/S1097-2765(00)80425-6. PMID 10882071.
• Hartley JL, Temple GF, Brasch MA (November 2000). "DNA cloning using in vitro site-specific recombination". Genome Res. 10 (11): 1788–95. doi:10.1101/gr.143000. PMC 310948. PMID 11076863.
• Njajou OT, Vaessen N, Joosse M, Berghuis B, van Dongen JW, Breuning MH, Snijders PJ, Rutten WP, Sandkuijl LA, Oostra BA, van Duijn CM, Heutink P (July 2001). "A mutation in SLC11A3 is associated with autosomal dominant hemochromatosis". Nat. Genet. 28 (3): 213–4. doi:10.1038/90038. PMID 11431687.
• Montosi G, Donovan A, Totaro A, Garuti C, Pignatti E, Cassanelli S, Trenor CC, Gasparini P, Andrews NC, Pietrangelo A (August 2001). "Autosomal-dominant hemochromatosis is associated with a mutation in the ferroportin (SLC11A3) gene". J. Clin. Invest. 108 (4): 619–23. doi:10.1172/JCI13468. PMC 209405. PMID 11518736.
• Press RD (December 2001). "Hemochromatosis caused by mutations in the iron-regulatory proteins ferroportin and H ferritin". Mol. Diagn. 6 (4): 347. doi:10.1054/modi.2001.0060347. PMID 11774199.
• Lee PL, Gelbart T, West C, Halloran C, Felitti V, Beutler E (2001). "A study of genes that may modulate the expression of hereditary hemochromatosis: transferrin receptor-1, ferroportin, ceruloplasmin, ferritin light and heavy chains, iron regulatory proteins (IRP)-1 and -2, and hepcidin". Blood Cells Mol. Dis. 27 (5): 783–802. doi:10.1006/bcmd.2001.0445. PMID 11783942.
• Rolfs A, Bonkovsky HL, Kohlroser JG, McNeal K, Sharma A, Berger UV, Hediger MA (April 2002). "Intestinal expression of genes involved in iron absorption in humans". Am. J. Physiol. Gastrointest. Liver Physiol. 282 (4): G598–607. doi:10.1152/ajpgi.00371.2001. PMID 11897618.
• Thomas C, Oates PS (April 2002). "IEC-6 cells are an appropriate model of intestinal iron absorption in rats". J. Nutr. 132 (4): 680–7. PMID 11925460.
• Wallace DF, Pedersen P, Dixon JL, Stephenson P, Searle JW, Powell LW, Subramaniam VN (July 2002). "Novel mutation in ferroportin1 is associated with autosomal dominant hemochromatosis". Blood 100 (2): 692–4. doi:10.1182/blood.v100.2.692. PMID 12091366.
• Devalia V, Carter K, Walker AP, Perkins SJ, Worwood M, May A, Dooley JS (July 2002). "Autosomal dominant reticuloendothelial iron overload associated with a 3-base pair deletion in the ferroportin 1 gene (SLC11A3)". Blood 100 (2): 695–7. doi:10.1182/blood-2001-11-0132. PMID 12091367.
• Roetto A, Merryweather-Clarke AT, Daraio F, Livesey K, Pointon JJ, Barbabietola G, Piga A, Mackie PH, Robson KJ, Camaschella C (July 2002). "A valine deletion of ferroportin 1: a common mutation in hemochromastosis type 4". Blood 100 (2): 733–4. doi:10.1182/blood-2002-03-0693. PMID 12123233.

External links

• ferroportin1 protein at the US National Library of Medicine Medical Subject Headings (MeSH)