ALDH2 — Aldehyde Dehydrogenase 2

ALDH2 — Aldehyde Dehydrogenase 2

Overview

ALDH2 — Aldehyde Dehydrogenase 2

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">ALDH2 — Aldehyde Dehydrogenase 2</th>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">4-HNE</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">NAD+</td>
<td>Cofactor</td>
</tr>
<tr>
<td class="label">SOD2</td>
<td>Antioxidant</td>
</tr>
<tr>
<td class="label">PGC-1alpha</td>
<td>Transcriptional</td>
</tr>
<tr>
<td class="label">PARK2/Parkin</td>
<td>Mitophagy</td>
</tr>
<tr>
<td class="label">SIRT3</td>
<td>Deacetylase</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/carcinoma" style="color:#ef9a9a">Carcinoma</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">81 edges</a></td>
</tr>
</table>

2 is a human gene. This page covers the gene's normal function, disease associations, expression patterns, and key research findings relevant to neurodegeneration.

Gene Overview

ALDH2 (Aldehyde Dehydrogenase 2) encodes a mitochondrial enzyme that catalyzes the oxidation of toxic aldehydes to their corresponding carboxylic acids. This NAD+-dependent enzyme plays a critical role in cellular detoxification, metabolizing harmful aldehydes generated during lipid peroxidation, alcohol metabolism, and oxidative stress. ALDH2 is particularly important in tissues with high metabolic activity and exposure to oxidative stress, including the heart, liver, and brain. The enzyme activity is essential for protecting cells from aldehyde-induced damage that contributes to neurodegeneration, cardiovascular disease, and cancer.

Protein Structure and Function

ALDH2 is a homotetrameric enzyme localized to the mitochondrial matrix. Each subunit contains:

• Catalytic domain: Contains the active site with catalytic cysteine (Cys302)
• NAD+ binding domain: Rossmann-fold structure for cofactor binding
• Oligomerization interface: Mediates tetramer formation

Catalytic Mechanism

Substrate Specificity

• 4-Hydroxynonenal (4-HNE): Major lipid peroxidation product
• Malondialdehyde (MDA): Another lipid peroxidation by-product
• Acetaldehyde: Ethanol metabolism product
• Acetylaldehyde: Formed during dopamine oxidation
• Propionaldehyde: Environmental exposure

Expression and Localization

ALDH2 is expressed at high levels in:

• Brain: Hippocampus, cerebral cortex, substantia nigra, cerebellum
• Heart: Cardiac myocytes
• Liver: Hepatocytes
• Kidney: Renal tubular cells
• Skeletal muscle: Muscle fibers

• Mitochondria (primary location)
• Synaptic terminals
• Axonal compartments
• Postsynaptic densities

Role in Neurodegeneration

ALDH2 is a critical player in protecting neurons from aldehyde-induced toxicity:

Alzheimer's Disease (AD)

• ALDH2 activity is significantly decreased in AD brains, particularly in hippocampus and cortex
• Accumulation of toxic aldehydes (4-HNE, MDA) contributes to neuronal death
• 4-HNE promotes tau hyperphosphorylation and amyloid-β toxicity
• The enzyme protects against lipid peroxidation-induced synaptic dysfunction
• ALDH2 rs671 (Glu504Lys) polymorphism increases AD risk in East Asian populations

Parkinson's Disease (PD)

• ALDH2 metabolizes acetaldehyde produced during dopamine oxidation
• The enzyme protects dopaminergic neurons from toxic aldehydes
• ALDH2 activity is reduced in the substantia nigra of PD patients
• The rs671 variant is associated with increased PD risk
• 4-HNE promotes α-synuclein aggregation and toxicity

Other Neurodegenerative Conditions

• Amyotrophic Lateral Sclerosis (ALS): ALDH2 protects motor neurons from oxidative damage
• Huntington's Disease: ALDH2 deficiency exacerbates mutant huntingtin toxicity
• Stroke and Brain Injury: ALDH2 limits damage from ischemic/reperfusion injury

Clinical Significance

Genetic Polymorphisms

• rs671 (Glu504Lys): Common in East Asians, reduces ALDH2 activity by ~40-80%
• Associated with increased AD and PD risk
• Affects alcohol tolerance and cardiovascular disease risk
• rs4646776: Associated with aldehyde metabolism efficiency
• rs2236672: Influences enzyme expression levels

Biomarker Potential

• ALDH2 activity in CSF reflects mitochondrial health in neurodegenerative diseases
• 4-HNE-ALDH2 adducts in brain tissue indicate oxidative stress burden
• Genetic testing for ALDH2 variants can inform disease risk

Therapeutic Implications

• ALDH2 activators: Alda-1 and related compounds enhance enzyme activity
• Gene therapy: Viral vector delivery of ALDH2 protects neurons in models
• Small molecule approaches: Enhancing ALDH2 expression or activity

Interactome

Key protein interactions and pathways:

See Also

• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)

External Links

• [PubMed](https://pubmed.ncbi.nlm.nih.gov/)
• [KEGG Pathways](https://www.genome.jp/kegg/pathway.html)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving ALDH2 — Aldehyde Dehydrogenase 2 discovered through SciDEX knowledge graph analysis: