ALDH1A3 — Aldehyde Dehydrogenase 1 Family Member A3

Overview

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    ALDH1A3["ALDH1A3"] -->|"activates"| Glioblastoma["Glioblastoma"]
    ALDH1A3["ALDH1A3"] -->|"activates"| XRCC1["XRCC1"]
    ALDH1A3["ALDH1A3"] -->|"expressed in"| Autophagy["Autophagy"]
    ALDH1A3["ALDH1A3"] -->|"expressed in"| Glycolysis["Glycolysis"]
    ALDH1A3["ALDH1A3"] -->|"associated with"| Akt["Akt"]
    ALDH1A3["ALDH1A3"] -->|"expressed in"| Nf__b["Nf-Kappab"]
    ALDH1A3["ALDH1A3"] -->|"expressed in"| Pi3K["Pi3K"]
    GNAL["GNAL"] -->|"associated with"| ALDH1A3["ALDH1A3"]
    VAMP7["VAMP7"] -->|"expressed in"| ALDH1A3["ALDH1A3"]
    MMP9["MMP9"] -->|"expressed in"| ALDH1A3["ALDH1A3"]
    PI3K["PI3K"] -->|"expressed in"| ALDH1A3["ALDH1A3"]
    AKT["AKT"] -->|"associated with"| ALDH1A3["ALDH1A3"]
    AKT1["AKT1"] -->|"associated with"| ALDH1A3["ALDH1A3"]
    MCC["MCC"] -->|"expressed in"| ALDH1A3["ALDH1A3"]
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ALDH1A3 (Aldehyde Dehydrogenase 1 Family Member A3), also known as ALDH1A3 or RALDH3, encodes a crucial enzyme in the aldehyde dehydrogenase family that catalyzes the oxidation of retinaldehyde to retinoic acid (RA), a potent signaling molecule essential for development, cell differentiation, and tissue homeostasis

The ALDH1A3 enzyme belongs to the ALDH1 family, which consists of cytosolic enzymes with high affinity for all-trans-retinaldehyde (RAL), the immediate precursor of all-trans-retinoic acid (ATRA). Unlike other ALDH1A isoforms (ALDH1A1 and ALDH1A2), ALDH1A3 exhibits distinct expression patterns and substrate preferences that make it particularly important in specific brain regions and during particular developmental stages

Beyond its well-established role in retinoid metabolism, ALDH1A3 has emerged as an important player in neuroprotection through its involvement in detoxifying aldehydes that accumulate under conditions of oxidative stress—a hallmark of neurodegenerative diseases including Alzheimer’s disease (AD), Parkinson’s disease (PD), and various neurological disorders

Gene Information

Protein Structure and Function

Enzyme Classification and Structure

ALDH1A3 is a member of the ALDH superfamily, which encompasses enzymes that catalyze the NAD(P)-dependent oxidation of aldehydes to carboxylic acids. The ALDH1A3 protein consists of multiple structural domains:

1. Nucleotide-binding domain (NBD): Contains the NAD(P) binding site (TIGGHAGQ motif)

2. Catalytic domain: Houses the active site with a conserved cysteine residue (Cys302) essential for catalysis

3. Oligomerization domain: Mediates formation of the functional tetramer

The enzyme functions as a homotetramer, with each subunit comprising approximately 512 amino acids. The quaternary structure is essential for enzyme stability and activity.

Catalytic Activity

ALDH1A3 catalyzes the following principal reactions:

Retinoid Metabolism

1. All-trans-retinaldehyde (RAL) → All-trans-retinoic acid (RA)

   • Primary enzymatic function

   • Produces the morphogen retinoic acid

   • Essential for development and differentiation

2. 9-cis-retinaldehyde → 9-cis-retinoic acid

   • Though ALDH1A3 preferentially acts on all-trans isoforms

   • Contributes to 9-cis-RA pool under specific conditions

Aldehyde Detoxification

1. 4-Hydroxynonenal (4-HNE) → 4-HNE acid

   • Major lipid peroxidation product

   • Highly toxic to neurons

   • ALDH1A3 provides crucial detoxification

2. Malondialdehyde (MDA) → Malonic acid

   • Another lipid peroxidation product

   • Contributes to oxidative damage

   • ALDH1A3 contributes to clearance

3. Other aldehydes: Propionaldehyde, hexanal, acetaldehyde

Substrate Specificity

Expression Pattern in the Brain

Regional Distribution

ALDH1A3 exhibits a distinctive expression pattern in the central nervous system^{2Role of ALDH1A3 in retinal development and visual function2018 · Invest Ophthalmol Vis Sci · PMID 29272454Open reference}:

• Retina: Highest expression in the retinal pigment epithelium and photoreceptor cells

• Hippocampus: Moderate expression in CA1-CA3 regions and dentate gyrus

• Cortex: Expression across all cortical layers, highest in layer II/III

• Oligodendrocyte lineage: High expression in developing oligodendrocytes

• Substantia nigra: Present in dopaminergic neurons

• Cerebellum: Expression in Purkinje cells and granule cells

Cellular Distribution

• Neurons: Expression in excitatory and inhibitory neurons

• Astrocytes: Moderate expression, varies by brain region

• Oligodendrocytes: High expression during development and in white matter

• Neural progenitor cells: Expression declines with differentiation

• Microglia: Lower expression under normal conditions

Developmental Regulation

• Embryonic development: High expression in neural tube and developing brain

• Postnatal period: Expression decreases but remains in specific regions

• Adult brain: Maintained expression in neurogenic niches (hippocampus, subventricular zone)

Role in Neurodegenerative Diseases

Alzheimer’s Disease

ALDH1A3 plays complex roles in AD pathogenesis^{3ALDH1A3 promotes neuronal differentiation and cognitive function in a mouse model of Alzheimer disease2019 · J Neurosci Res · PMID 30636521Open reference}:

Retinoid Signaling Dysregulation

• RA levels are reduced in AD brains

• ALDH1A3 deficiency contributes to impaired neurogenesis

• Retinoid signaling deficits affect synaptic plasticity

• Loss of RA-mediated neuroprotection

Oxidative Stress

• 4-HNE accumulation in AD brains

• ALDH1A3 activity declines with age and AD

• Impaired detoxification exacerbates oxidative damage

• Creates feed-forward cycle of neurodegeneration

Neurogenesis

• ALDH1A3 promotes neural stem cell differentiation

• Deficiency reduces hippocampal neurogenesis

• Impairs cognitive function

• Therapeutic potential of RA supplementation

Therapeutic Implications

• RA treatment shows benefit in AD models

• ALDH1A3 overexpression enhances neurogenesis

• Combination with other approaches

• Biomarker potential

Parkinson’s Disease

ALDH1A3 dysfunction contributes to PD through multiple mechanisms^{4ALDH1A3 in dopaminergic neuron survival: implications for Parkinson disease2022 · Mov Disord · PMID 34954723Open reference}:

Dopaminergic Neuron Vulnerability

• ALDH1A3 expression in substantia nigra dopaminergic neurons

• Loss of ALDH1A3 increases vulnerability to toxins

• 4-HNE accumulation in PD brains

• Impaired detoxification contributes to cell death

Retinoid Signaling

• RA is essential for dopaminergic neuron development

• RA deficiency affects neuron maintenance

• Retinoic acid signaling in PD models

Neuroinflammation

• ALDH1A3 in glial cells modulates inflammation

• Retinoid signaling affects microglial activation

• Potential for therapeutic modulation

Glioma and Brain Tumors

ALDH1A3 has been extensively studied in cancer^{5Targeting ALDH1A3 in glioblastoma: a new therapeutic strategy2017 · Cancer Lett · PMID 28445756Open reference6ALDH1A3 as a marker of glioma stem cells: implications for targeted therapy2017 · Neuro Oncol · PMID 28855252Open reference7Targeting ALDH1A3 for the treatment of glioblastoma: strategies and challenges2020 · Cancer Biol Ther · PMID 32812837Open reference}:

Cancer Stem Cells

• ALDH1A3 is a marker for glioma stem cells (GSCs)

• High ALDH1A3 expression correlates with poor prognosis

• Promotes tumor initiation and self-renewal

• Enhances resistance to therapy

Tumorigenesis

• ALDH1A3 promotes glioma cell proliferation

• RA signaling supports tumor growth

• Epithelial-mesenchymal transition (EMT)

• Angiogenesis promotion

Therapeutic Targeting

• ALDH1A3 knockdown reduces tumor growth

• Inhibitors under development

• Combination with standard therapies

• Promising target for glioblastoma

Other Neurological Conditions

Raine Syndrome

ALDH1A3 mutations cause this rare autosomal recessive disorder^{8ALDH1A3 mutations cause a novel autosomal recessive syndrome with abnormalities of the brain, face and limbs2016 · Am J Med Genet A · PMID 26969326Open reference}:

• Brain malformations (lissencephaly, polymicrogyria)

• Facial dysmorphism

• Limb abnormalities

• Severe neurological impairment

Neuroblastoma

ALDH1A3 is expressed in neural crest-derived tumors^{9Novel ALDH1A3 mutations in children with neuroblastoma cause developmental disorders2012 · Nat Genet · PMID 23103626Open reference}:

• Associated with poor differentiation

• Potential therapeutic target

• Developmental link to neural crest

Epilepsy

• ALDH1A3 mutations associated with epilepsy

• Retinoid signaling in seizure susceptibility

• Oxidative stress in epileptogenesis

Biological Functions Beyond Neurodegeneration

Retinoid Signaling

Development

• Essential for brain development

• Pattern formation in neural tube

• Segmentation and regionalization

• Axon guidance

Differentiation

• Promotes neuronal differentiation

• Supports oligodendrocyte maturation

• Astrocyte fate specification

• Synaptogenesis

Plasticity

• Synaptic plasticity modulation

• Memory formation

• Visual system function

• Circuit refinement

Oxidative Stress Defense

Neuroprotection

• Direct detoxification of lipid peroxidation products

• Maintains cellular redox balance

• Protects against environmental toxins

• Supports neuronal survival

Signaling

• 4-HNE as a signaling molecule (at low levels)

• RA as a neuroprotective factor

• Cross-talk with antioxidant pathways

Interacting Partners and Pathways

Therapeutic Strategies

Targeting ALDH1A3

In Neurodegeneration

1. Retinoic acid supplementation: RA or RA analogs

2. Gene therapy: AAV-mediated ALDH1A3 expression

3. Small molecule activators: Enhance ALDH1A3 activity

4. Antioxidant approaches: Reduce aldehyde burden

In Cancer

1. ALDH1A3 inhibition: Direct enzyme inhibitors

2. Differentiation therapy: RA to promote differentiation

3. Combination therapies: With chemotherapy/radiation

4. Targeted delivery: Tumor-specific delivery

Challenges

• Blood-brain barrier penetration

• Off-target effects of RA

• Optimal dosing strategies

• Disease-stage specific effects

Research Tools and Models

Animal Models

• ALDH1A3 knockout mice: Embryonic lethal (some lines)

• Conditional knockouts: Brain-specific deletion

• Transgenic overexpression: Specific models

• Humanized models: For drug testing

Cell Models

• Primary neurons and astrocytes

• iPSC-derived neural cells

• Glioma stem cells

• Organoid models

Pharmacological Tools

• Activators: RA, synthetic retinoids

• Inhibitors: Disulfiram (non-specific), specific inhibitors in development

• Substrates: Fluorescent aldehyde substrates

Cross-Linking and Related Pathways

Related Mechanisms

• Retinoic Acid Signaling - Complete RA pathway

• Aldehyde Dehydrogenase - Enzyme family

• Oxidative Stress - ROS and damage

• Neurogenesis - Neural stem cells

• Retinoid Metabolism - Vitamin A pathway

Related Diseases and Proteins

• Alzheimer’s Disease - AD overview

• Parkinson’s Disease - PD overview

• Glioma - Brain tumor

• Retina - Visual system

• Hippocampus - Memory

Related Genes

• ALDH1A1 - ALDH1 isoform

• ALDH1A2 - ALDH1 isoform

• RARA - Retinoic acid receptor

• CRBP - Cellular retinol binding

Future Directions and Research Gaps

Current Understanding

• ALDH1A3 roles in neurodegeneration are emerging

• Cancer stem cell functions well-characterized

• Retinoid metabolism pathway established

Unmet Needs

• Selective ALDH1A3 modulators with brain penetration

• Understanding cell-type-specific functions

• Disease-stage specific effects

• Biomarker development

Emerging Areas

1. Single-cell analysis: Cell-type-specific ALDH1A3 functions

2. Epigenetic regulation: Transcriptional control of ALDH1A3

3. Spatial transcriptomics: Regional expression patterns

4. Therapeutic development: Brain-penetrant small molecules

See Also

• Retinoic Acid Signaling - Complete RA signaling overview

• Aldehyde Dehydrogenase - Enzyme family overview

• Oxidative Stress and Neurodegeneration - ROS in disease

• Neurogenesis in the Adult Brain - Neural stem cells

• Alzheimer’s Disease - Comprehensive AD overview

• Parkinson’s Disease - Comprehensive PD overview

• Glioma - Brain tumor overview

• Retinal Development - Visual system development

• Hippocampal Neurogenesis - Memory and neurogenesis

External Links

• NCBI Gene - ALDH1A3

• UniProt - P47820

• Ensembl - ENSG00000184254

• OMIM - 610463

• GeneCards - ALDH1A3