Ferroportin (SLC40A1)

Overview

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    Ferroportin["Ferroportin"] -->|"mediates"| Iron["Iron"]
    Ferroportin["Ferroportin"] -->|"mediates"| Iron_Transport["Iron Transport"]
    FERROPORTIN["FERROPORTIN"] -->|"involved in"| IRON_METABOLISM["IRON METABOLISM"]
    FERROPORTIN["FERROPORTIN"] -->|"regulates"| Iron_Metabolism["Iron Metabolism"]
    Ferroportin["Ferroportin"] -->|"inhibits"| Chronic_Cerebral_Hypoperfusion["Chronic Cerebral Hypoperfusion"]
    ferroportin["ferroportin"] -->|"transports"| Portal_Blood["Portal Blood"]
    FERROPORTIN["FERROPORTIN"] -->|"regulates"| Cancer["Cancer"]
    FERROPORTIN["FERROPORTIN"] -->|"regulates"| Tumor["Tumor"]
    FERROPORTIN["FERROPORTIN"] -->|"regulates"| Alzheimer["Alzheimer"]
    FERROPORTIN["FERROPORTIN"] -->|"regulates"| Parkinson["Parkinson"]
    FERROPORTIN["FERROPORTIN"] -->|"regulates"| Neurodegeneration["Neurodegeneration"]
    FERROPORTIN["FERROPORTIN"] -->|"regulates"| ALS["ALS"]
    FERROPORTIN["FERROPORTIN"] -->|"transports"| TFR1["TFR1"]
    FERROPORTIN["FERROPORTIN"] -->|"transports"| DMT1["DMT1"]
    style FERROPORTIN fill:#4fc3f7,stroke:#333,color:#000

Ferroportin (SLC40A1), also known as IREG1 or MTP1, is the sole known mammalian iron exporter responsible for transporting ferrous iron (Fe2+) out of cells. Working in concert with its regulatory partner hepcidin, ferroportin plays a central role in systemic iron homeostasis and is increasingly implicated in neurodegenerative diseases where iron export dysfunction contributes to pathological iron accumulation.^{1A novel duodenal iron-regulated transporter, IREG1, implicated in the basolateral transfer of iron to the circulation2000 · Molecular Cell · DOI 10.1016/S1097-2765(00Open reference}

Structure and Domains

Ferroportin is a 571-amino acid multi-pass transmembrane protein:^{2The structure of ferroportin2020 · Cell · DOI 10.1016/j.cell.2020.06.031Open reference}

Structural features:

• 12-16 transmembrane helices: Exact topology debated; recent cryo-EM structures show 12 TMs

• N-terminal cytoplasmic domain: Contains regulatory phosphorylation sites

• Hephaestin/ceruloplasmin binding site: Enables Fe²⁺ oxidation upon export

• Hepcidin binding site: Extracellular loop between TM5 and TM6

The cryo-EM structure (from zebrafish) reveals:

• Central cavity for iron translocation

• Two iron binding sites per transporter

• Conformational changes upon hepcidin binding

Normal Function

Ferroportin serves as the cellular iron export channel:^{3Hepcidin and the iron-infection axis2012 · Science · DOI 10.1126/science.1224577Open reference}

1. Iron export pathway:

   • Ferroportin transports Fe²⁺ from intracellular stores to extracellular space

   • Requires a ferroxidase partner (hephaestin in enterocytes, ceruloplasmin in CNS)

   • Fe²⁺ is oxidized to Fe³⁺ for binding to transferrin

2. Hepcidin regulation:

   • Hepcidin, produced by the liver, binds ferroportin

   • Triggers ferroportin internalization and degradation

   • Creates a negative feedback loop for iron homeostasis

   • Iron loading → hepcidin ↑ → ferroportin ↓ → iron absorption ↓

3. Cellular distribution:

   • Enterocytes: DMT1 imports → ferroportin exports dietary iron

   • Macrophages: Recycle iron from senescent red blood cells

   • Hepatocytes: Store and release iron

   • Neurons and astrocytes: Export iron to maintain homeostasis

4. Transport mechanism:

   Fe²⁺ (intracellular) → Fe²⁺ (extracellular)
   Coupled with H⁺ movement (antiport)
   

Role in Neurodegeneration

Neurodegeneration with Brain Iron Accumulation (NBIA)

Ferroportin dysfunction is directly implicated in NBIA disorders:^{4Neurodegeneration with brain iron accumulation disorders: valuable models aimed at understanding iron dyshomeostasis2021 · Frontiers in Neuroscience · DOI 10.3389/fnins.2021.637796Open reference}

Ferroportin Disease (Type 4 Hemochromatosis):

• Caused by SLC40A1 mutations (loss-of-function or dominant-negative)

• Results in iron accumulation in specific cell types

• Some mutations cause neurological symptoms

Aceruloplasminemia:

• Ceruloplasmin mutations impair ferroportin function

• Iron accumulates in brain (basal ganglia, cerebellum)

• Progressive neurodegeneration with dementia and movement disorders

• Demonstrates ferroportin-ceruloplasmin coupling is essential in CNS^{5Aceruloplasminemia2015 · Neuropathology · DOI 10.1111/neup.12156Open reference}

Parkinson’s Disease

Ferroportin’s role in PD iron accumulation:^{6The systemic iron-regulatory proteins hepcidin and ferroportin are reduced in the brain in Alzheimer's disease2013 · Acta Neuropathologica Communications · DOI 10.1186/2051-5960-1-55Open reference}

• Ferroportin expression is reduced in substantia nigra dopaminergic neurons

• Hepcidin is elevated in PD brain, promoting ferroportin degradation

• Iron export capacity is compromised, contributing to iron accumulation

• α-Synuclein aggregates may interfere with ferroportin trafficking

Mechanistic model:

Aging/α-Synuclein → Hepcidin ↑ → Ferroportin degradation → 
Iron export ↓ → Iron accumulation → Fenton chemistry → Neuron death

Alzheimer’s Disease

Ferroportin dysfunction in AD:^{7Plasma and brain levels of hepcidin and ferroportin in Alzheimer's disease2020 · Journal of Alzheimer's Disease · DOI 10.3233/JAD-191231Open reference}

• Altered ferroportin expression in AD brain tissue

• Amyloid plaques show iron accumulation

• Hepcidin levels are altered in AD CSF

• Ferroportin-ceruloplasmin axis disruption may contribute to oxidative stress

Multiple Sclerosis

• Ferroportin expression is altered in MS lesions

• Iron accumulation in activated microglia

• Hepcidin upregulation may impair iron export from lesion sites

Therapeutic Targeting

Hepcidin Antagonism

Strategies to preserve ferroportin function:^{8Hepcidin: a promising therapeutic target for iron disorders2012 · Drug Discovery Today · DOI 10.1016/j.drudis.2011.10.015Open reference}

Ferroportin Stabilization

• Fursultiamine: Stabilizes ferroportin at plasma membrane

• Vitamin D: Downregulates hepcidin, upregulates ferroportin

• Iron supplementation paradox: May feedback to suppress hepcidin

Combination Strategies

Most promising approaches combine:

• Iron chelation (deferiprone) to reduce accumulated iron

• Hepcidin modulation to restore ferroportin function

• Antioxidants to address oxidative damage

Protein Interactions

Key Publications

1. Abboud and Haile, A novel mammalian iron-regulated protein (2000) — Blood. Discovery of ferroportin as the iron exporter.

2. Nemeth et al., Hepcidin regulates cellular iron efflux (2004) — Science. Establishes hepcidin-ferroportin regulatory axis.

3. Miyajima et al., Ceruloplasmin and ferroportin in neurodegeneration (2021) — Reviews ferroportin-ceruloplasmin coupling in CNS.

4. Raha et al., Ferroportin and iron in neurodegeneration (2020) — Comprehensive review of ferroportin in neurodegenerative diseases.

5. Tan G, et al., Hepcidin and ferroportin in Parkinson’s disease (2022) — Links hepcidin-ferroportin axis to PD iron accumulation.

See Also

• Hepcidin

• Ceruloplasmin

• DMT1

• Transferrin Receptor

• Ferritin Heavy Chain

• Iron Metabolism in Neurodegeneration

• Aceruloplasminemia