[^1]
- Gene: [FTH1](/genes/fth1)
[^2]
- UniProt: [P02794](https://www.uniprot.org/uniprot/P02794)
[^3]
- Molecular Weight: ~21 kDa
- Subcellular Location: Cytoplasm, nucleus, mitochondria
- PDB Structures: [2FHA](https://www.rcsb.org/structure/2FHA), [4DZ0](https://www.rcsb.org/structure/4DZ0)
Ferritin heavy chain (FTH1) is the ferroxidase component of ferritin, the primary intracellular iron storage complex. Together with ferritin light chain (FTL), FTH1 forms a 24-subunit spherical complex capable of storing up to 4,500 iron atoms. The ferroxidase activity of FTH1 converts toxic Fe2+ to Fe3+ for safe storage, playing a critical role in cellular iron homeostasis and protection against iron-mediated oxidative damage.
The ferritin complex consists of 24 subunits that self-assemble into a hollow spherical shell with 4-3-2 symmetry. FTH1 contributes ferroxidase activity through a di-iron center located in the four-helix bundle core:
- Four-helix bundle: The central structural motif containing the ferroxidase center
- Ferroxidase center: Binds two iron atoms and catalyzes Fe2+ oxidation
- Long loop: Connects helices B and C, involved in subunit interactions
- C-terminal E-helix: Contributes to inner cavity iron nucleation sites
The H:L subunit ratio determines ferritin properties, with H-rich ferritins having higher ferroxidase activity.
¶ Iron Storage and Detoxification
FTH1 catalyzes the oxidation of Fe2+ to Fe3+ at the ferroxidase center, after which iron moves to the inner cavity for storage as ferrihydrite mineral. This dual function:
- Removes toxic free iron that catalyzes Fenton reactions
- Stores iron for future metabolic needs
- Regulates iron bioavailability in response to cellular demands
FTH1 has emerging roles beyond iron storage:
- Cell proliferation: Supports rapid cell division through iron supply
- Development: Essential for embryogenesis in mice
- DNA protection: Shields nuclear DNA from iron-mediated damage
- Stress response: Upregulated by oxidative stress via Nrf2
Ferritin dysfunction contributes to several NBIA disorders:
- Neuroferritinopathy: Mutations in FTL cause abnormal ferritin assembly and iron accumulation, though FTH1 is secondarily affected
- Aceruloplasminemia: Iron overload occurs despite normal ferritin, with ferritin becoming iron-saturated
- PKAN and PLA2G6: Secondary ferritin accumulation in iron-laden regions
FTH1 is implicated in AD pathology through multiple mechanisms:
- Amyloid-iron interactions: Ferritin colocalizes with amyloid plaques
- Microglial iron handling: Activated microglia upregulate ferritin
- Hippocampal vulnerability: Ferritin loss in vulnerable neurons
- CSF ferritin elevation: Correlates with disease severity
Iron accumulation in the substantia nigra involves ferritin:
- Nigral ferritin reduction: Lower ferritin despite high iron
- Dopaminergic vulnerability: Low ferritin in vulnerable neurons
- Ferroptosis susceptibility: Insufficient ferritin to handle iron load
FTH1 is a key ferroptosis regulator:
- Iron sequestration: Prevents lipid peroxidation by reducing labile iron
- Nrf2 target: Upregulated during ferroptosis as protective response
- Therapeutic target: Ferritin induction can suppress ferroptotic cell death
Ferritin levels inform chelation strategies:
- Deferiprone: Can cross BBB, may redistribute iron to ferritin
- Deferoxamine: Limited brain penetration
- Combined approaches: Chelation plus ferritin induction
Approaches to boost ferritin for neuroprotection:
- Nrf2 activators: Increase FTH1 transcription
- Iron supplementation: In iron-deficient conditions
- Gene therapy: FTH1 delivery to vulnerable neurons
Ferritin serves as a biomarker:
- CSF ferritin: Elevated in neurodegenerative diseases
- Serum ferritin: Reflects systemic iron status
- MRI ferritin imaging: Emerging technique for brain iron assessment
| Interactor |
Relationship |
Functional Relevance |
| Ferritin Light Chain |
Heteropolymer |
Forms 24-mer complex |
| IRP1/2 |
Post-transcriptional regulator |
Controls FTH1 mRNA translation |
| Nrf2 |
Transcription factor |
Antioxidant response element binding |
| Transferrin |
Iron uptake |
Supplies cellular iron |
| Ferroportin |
Iron export |
Releases stored iron |
- tau-protein — Related tau kinase substrate in AD](/proteins)
- amyloid-beta — Related APP cleavage product](/proteins)
- GSK3B — Major kinase in neurodegeneration](/proteins)
- CDK5 — Another tau kinase](/genes)
- BACE1 — Beta-secretase in amyloidogenesis
- UniProt - Protein sequence and functional data
- PubMed - Biomedical literature
- PDB - Protein structure data