ALDH1A3 (Aldehyde Dehydrogenase 1 Family Member A3) is a member of the aldehyde dehydrogenase family that catalyzes the NAD+-dependent oxidation of retinaldehyde to retinoic acid. It plays crucial roles in retinoid metabolism, oxidative stress response, and has been increasingly implicated in neurodegenerative diseases, particularly Alzheimer's Disease and Parkinson's Disease.
| Property |
Value |
| UniProt ID |
P47869 |
| Molecular Weight |
~56 kDa |
| Protein Length |
505 amino acids |
| Cellular Localization |
Cytosol |
| PDB Structures |
4WSC, 5L2H |
| Enzyme Classification |
EC 1.2.1.3 |
¶ Domain Architecture
- N-terminal NAD-binding domain: Rossmann fold, ~180 aa
- Consensus NAD-binding motif: TGXGGXXGXXG
- Catalytic domain: ~320 aa, contains catalytic residues
- Substrate-binding pocket: Specificity for retinaldehyde and other aldehydes
- C-terminal region: Oligomerization interface
- Forms tetramers in active form
- Catalytic cysteine (Cys302) in active site
- Oxyanion hole stabilized by residues
- Multiple substrate recognition sites
ALDH1A3 catalyzes the oxidation of aldehydes using NAD+ as cofactor:
- Retinaldehyde Metabolism: Converts retinaldehyde to retinoic acid
- Critical for retinoid signaling in brain
- Regulates gene expression via retinoic acid response elements
- Detoxification: Oxidizes toxic aldehydes
- 4-Hydroxy-2-nonenal (4-HNE)
- Malondialdehyde (MDA)
- Acetaldehyde
- NADH Production: Generates NADH in aldehyde oxidation
| Process |
ALDH1A3 Role |
| Retinoic Acid Synthesis |
Major source in neural tissue |
| Oxidative Stress Defense |
Detoxifies lipid peroxidation products |
| Neurogenesis |
Retinoic acid regulates neural stem cells |
| Synaptic Plasticity |
Retinoid signaling in LTP/LTD |
- Brain: High expression in hippocampus, cortex, cerebellum
- Neurons: Expressed in excitatory and inhibitory neurons
- Glia: Present in astrocytes
- Development: Important for brain development
ALDH1A3 is significantly altered in AD brain:
- Expression Changes: Reduced ALDH1A3 in AD hippocampus and entorhinal cortex
- Retinoic Acid Signaling: Impaired RA signaling contributes to synaptic deficits
- Oxidative Stress: Reduced detoxification of 4-HNE
- Aβ Toxicity: ALDH1A3 protects against amyloid-beta induced cell death
- Therapeutic Potential: RA supplementation may help restore function
ALDH1A3 deficiency is particularly notable in PD:
- Dopaminergic Neurons: Severely reduced ALDH1A3 in substantia nigra
- Neuronal Vulnerability: Low ALDH1A3 makes neurons more susceptible to toxins
- Genetic Association: ALDH1A3 variants linked to PD risk
- MPTP Toxicity: ALDH1A3 activity determines sensitivity to MPTP
Amyotrophic Lateral Sclerosis:
- Reduced ALDH1A3 in motor neurons
- Contributes to oxidative damage accumulation
Huntington's Disease:
- Altered retinoic acid signaling
- Impaired aldehyde detoxification
Age-Related Cognitive Decline:
- Progressive reduction in ALDH1A3 with aging
- Contributes to cognitive impairment
Oxidative Stress → Lipid Peroxidation → 4-HNE Production
↓
ALDH1A3 (detoxification)
↓
↓ (if insufficient)
Neuronal Death
| Approach |
Mechanism |
Status |
| Retinoic Acid Therapy |
Restore RA signaling |
Clinical trials |
| ALDH1A3 Activators |
Boost enzyme activity |
Preclinical |
| Gene Therapy |
Increase ALDH1A3 expression |
Theoretical |
| Antioxidant Combos |
Reduce aldehyde load |
Research |
- Retinoic Acid: FDA-approved for other uses, CNS trials ongoing
- Alda-1: ALDH activator (primarily ALDH2)
- Disulfiram: ALDH inhibitor (caution: aldehyde toxicity)
- N-acetylcysteine: Supports glutathione, reduces aldehyde load
- Blood-brain barrier penetration needed
- RA dosage must be carefully controlled
- Potential for teratogenicity
- Combination approaches may be needed
- ALDH1A3 gene located on chromosome 15q26.2
- Essential: Knockout is embryonic lethal in mice
- Brain-specific: Alternative promoters for neural expression
- PD Risk: Some SNPs associated with increased risk
- Developmental: Mutations cause retinal and neurological abnormalities
- Aldh1a3 knockout mice: Viable but with neurological deficits
- Conditional knockouts: Brain-specific deletion models
- Overexpression: Protective in toxin models
- ALDH1A3 activity: Lower in PD patient fibroblasts
- Retinoic acid levels: Reduced in AD/PD CSF
- 4-HNE adducts: Elevated when ALDH1A3 is deficient
| Substrate |
Product |
Pathway |
| Retinaldehyde |
Retinoic acid |
Retinoid signaling |
| 4-HNE |
4-HNE acid |
Oxidative stress defense |
| Malondialdehyde |
Malonic acid |
Lipid peroxidation |
| Acetaldehyde |
Acetate |
Alcohol metabolism |
- Retinaldehyde dehydrogenases: ALDH1A1, ALDH1A2
- Retinoic acid receptors: RAR, RXR
- Antioxidant enzymes: SOD, GPX
- Retinol binding proteins: CRBP, IRP