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| Symbol | BACH1 |
| Full Name | BTB Domain and CNC Homolog 1 |
| Chromosome | 21q21.3 |
| NCBI Gene | 571 |
| Ensembl | ENSG00000156273 |
| OMIM | 602751 |
| UniProt | O14867 |
| Diseases | [Alzheimer's Disease](/diseases/alzheimers), [Parkinson's Disease](/diseases/parkinsons-disease), [ALS](/diseases/als) |
| Expression | Ubiquitous, high in brain, liver, spleen |
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Transcriptional repressor competing with NRF2
Heme-sensing transcription factor
Regulates oxidative stress response genes |
BACH1 (BTB Domain and CNC Homolog 1) encodes a transcriptional repressor that competes with NRF2 for binding to antioxidant response elements (AREs) in the promoters of cytoprotective genes. BACH1 acts as a heme sensor — when intracellular heme levels rise (as occurs during oxidative stress or hemolysis), heme binds to BACH1's cysteine-proline (CP) motifs, triggering its nuclear export and proteasomal degradation. This derepression allows NRF2 to activate target genes including HMOX1 (heme oxygenase-1), NQO1, and glutathione synthesis enzymes.
In neurodegenerative diseases, the BACH1-NRF2 axis is a critical determinant of cellular resilience to oxidative stress. BACH1 inhibition represents an emerging therapeutic strategy for enhancing neuroprotective antioxidant responses in Alzheimer's disease, Parkinson's disease, and ALS.
The protein encoded by BACH1 is BACH1 Protein. See the protein page for detailed structural and functional information.
BACH1 functions as a cap'n'collar (CNC) family transcription factor that:
- Heterodimerizes with small Maf proteins (MafF, MafG, MafK) to bind Maf recognition elements (MAREs) and AREs
- Competes with NRF2 for ARE binding, acting as a constitutive repressor of antioxidant gene expression under basal conditions
- Represses HMOX1: The HMOX1 promoter contains multiple AREs that are occupied by BACH1-Maf heterodimers in the absence of stress
- Regulates iron metabolism: Controls ferritin heavy chain (FTH1) and ferroportin (SLC40A1) expression
BACH1 contains six CP motifs that serve as heme-binding sites:
- Heme binding induces conformational change, releasing BACH1 from DNA
- Heme-bound BACH1 is exported from the nucleus via CRM1/exportin-1
- Cytoplasmic heme-BACH1 is ubiquitinated by FBXL17 and degraded by the proteasome
- This creates a feed-forward loop: oxidative stress → heme release → BACH1 degradation → NRF2 activation
graph TD
A["Basal State"] --> B["BACH1-Maf on AREs"]
B --> C["Antioxidant genes REPRESSED"]
D["Oxidative Stress"] --> E["Heme release from proteins"]
E --> F["Heme binds BACH1 CP motifs"]
F --> GBACH1 nuclear export + degradation
G --> H["NRF2-Maf occupies AREs"]
H --> I["HMOX1, NQO1, GST, GCL ACTIVATED"]
I --> J["Cytoprotection"]
BACH1 dysregulation contributes to oxidative damage in AD:
- BACH1 protein levels are elevated in AD hippocampus, correlating with reduced HMOX1 expression
- Amyloid-beta induces oxidative stress but fails to adequately degrade BACH1 in aged neurons
- BACH1 knockout mice show enhanced HMOX1 expression and resistance to amyloid-beta-induced oxidative damage
- The BACH1 gene is located on chromosome 21, raising the possibility of gene dosage effects in Down syndrome-associated AD
In PD, BACH1 opposes neuroprotective NRF2 signaling:
- Dopaminergic neurons in the substantia nigra have high oxidative burden due to dopamine metabolism
- BACH1 repression of HMOX1 limits the ability of these neurons to cope with iron-mediated oxidative stress
- BACH1 inhibition enhances NRF2-dependent protection of dopaminergic neurons in MPTP models
- Alpha-synuclein aggregation impairs the KEAP1-NRF2 pathway, making BACH1 derepression critical
- Motor neurons show vulnerability to oxidative stress, partly mediated by BACH1 repression of antioxidant genes
- SOD1 mutant models show altered BACH1-NRF2 balance
- BACH1 inhibition is being explored as a strategy to enhance motor neuron resilience
BACH1 inhibitors are in development for neurodegenerative diseases:
- HMOX1 inducers: Compounds that promote BACH1 degradation and HMOX1 derepression
- Direct BACH1 inhibitors: Small molecules blocking BACH1-DNA interaction
- Heme mimetics: Synthetic compounds that bind BACH1 CP motifs, triggering its degradation
BACH1 is ubiquitously expressed with notable levels in:
- Brain: Cortical neurons, hippocampal neurons, substantia nigra dopaminergic neurons
- Liver: Hepatocytes (major site of heme metabolism)
- Spleen: Macrophages involved in erythrocyte clearance
- Bone marrow: Erythroid precursors
- Immune cells: Monocytes and macrophages (including microglia)