ADAM8 Gene

ADAM8 — A Disintegrin And Metalloproteinase Domain 8

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">ADAM Metallopeptidase Domain 8</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>ADAM8</td></tr>
<tr><td><strong>Full Name</strong></td><td>A Disintegrin And Metalloproteinase domain 8</td></tr>
<tr><td><strong>Chromosome</strong></td><td>10q26.3</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[242](https://www.ncbi.nlm.nih.gov/gene/242)</td></tr>
<tr><td><strong>OMIM</strong></td><td>[602432](https://www.omim.org/entry/602432)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000151617</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[O43506](https://www.uniprot.org/uniprot/O43506)</td>
<tr><td><strong>Protein Length</strong></td><td>833 amino acids</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Alzheimer's Disease, Parkinson's Disease, Neuroinflammation, Cancer</td></tr>
</table>
</div>

Overview

ADAM8 — A Disintegrin And Metalloproteinase Domain 8

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">ADAM Metallopeptidase Domain 8</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>ADAM8</td></tr>
<tr><td><strong>Full Name</strong></td><td>A Disintegrin And Metalloproteinase domain 8</td></tr>
<tr><td><strong>Chromosome</strong></td><td>10q26.3</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[242](https://www.ncbi.nlm.nih.gov/gene/242)</td></tr>
<tr><td><strong>OMIM</strong></td><td>[602432](https://www.omim.org/entry/602432)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000151617</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[O43506](https://www.uniprot.org/uniprot/O43506)</td>
<tr><td><strong>Protein Length</strong></td><td>833 amino acids</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Alzheimer's Disease, Parkinson's Disease, Neuroinflammation, Cancer</td></tr>
</table>
</div>

Overview

ADAM8 (A Disintegrin And Metalloproteinase domain 8) is a member of the ADAM (A Disintegrin And Metalloproteinase) family of zinc-dependent metalloproteases. Located on chromosome 10q26.3, ADAM8 encodes a type I transmembrane protein involved in cell adhesion, proteolysis, and signaling. ADAM8 has emerged as an important regulator of [neuroinflammation](/mechanisms/neuroinflammation), [amyloid processing](/mechanisms/amyloid-cascade), and [blood-brain barrier](/entities/blood-brain-barrier) function in [Alzheimer's disease](/diseases/alzheimers-disease) and [Parkinson's disease](/diseases/parkinsons-disease) [@yang2018].

The protein is highly expressed in immune cells and in the brain, particularly in [microglia](/cell-types/microglia), [astrocytes](/cell-types/astrocytes), and neurons. ADAM8's proteolytic activity and cell adhesion functions make it a key player in neuroinflammatory processes and a potential therapeutic target for neurodegenerative diseases.

Structure and Biochemistry

Protein Domain Architecture

ADAM8 possesses the canonical ADAM family structure consisting of multiple functional domains [@edwards2008]:

Catalytic Mechanism

The metalloproteinase domain contains:

• Zinc-binding site: Essential for proteolytic activity
• Active site: HExGHxxGxxH consensus sequence coordinating zinc ion
• Substrate-binding groove: Determines substrate specificity

• Autocatalytic cleavage: Prodomain removal activates the protease
• Furin-mediated processing: Furin-like convertases in the secretory pathway
• Phosphorylation: Kinase modifications can regulate activity

Post-Translational Modifications

• N-glycosylation: Multiple N-linked glycosylation sites in the extracellular domain
• Disulfide bonds: Cysteine residues form intra- and inter-domain bonds
• Palmitoylation: May modulate membrane association
• Shedding: The extracellular domain can be shed as a soluble protein

Normal Physiological Function

Proteolytic Activity

ADAM8 cleaves a diverse range of substrates [@blobel2015]:

| Substrate | Function | Relevance |
|-----------|----------|-----------|
| [APP](/proteins/app) | Amyloid precursor protein | Amyloid-beta generation |
| TNF-alpha | Pro-inflammatory cytokine | Neuroinflammation |
| IL-6 | Pro-inflammatory cytokine | Neuroinflammation |
| NCAM | Neural cell adhesion molecule | Neuronal migration |
| L1CAM | Cell adhesion molecule | Axon guidance |
| Notch | Receptor protein | Neurogenesis |
| EGF | Growth factor | Cell proliferation |
| CD44 | Hyaluronic acid receptor | Cell adhesion |

Cell Adhesion Functions

The disintegrin domain mediates multiple adhesion functions:

• Integrin binding: Interacts with integrin receptors on neighboring cells
• Cell-matrix interactions: Facilitates attachment to extracellular matrix
• Neuronal migration: Guides developing neurons during migration
• Synaptic plasticity: Modulates synaptic structure and function

Immune System Functions

ADAM8 plays important roles in immune cell function [@naus2016]:

• Leukocyte extravasation: Facilitates transendothelial migration
• Cytokine release: Cleaves membrane-bound cytokines to soluble forms
• Cell activation: Regulates immune cell activation states
• Inflammatory responses: Modulates inflammatory signaling cascades

Nervous System Functions

In the nervous system, ADAM8 regulates [@murphy2018]:

• Neurogenesis: Controls neural progenitor cell differentiation
• Neuronal survival: Provides trophic support through protease activity
• Synapse formation: Regulates synaptic assembly and refinement
• Axon guidance: Cleaves guidance molecules during development

Expression Pattern

Tissue Distribution

ADAM8 is expressed in multiple tissues:

• Brain: Highest expression in the nervous system
• Immune system: Monocytes, neutrophils, lymphocytes, macrophages
• Lung: Epithelial cells and immune cells
• Spleen: White pulp and immune cells
• Bone marrow: Hematopoietic cells

Brain Regional Distribution

Within the brain, ADAM8 exhibits region-specific expression:

• Hippocampus: High expression in CA1 and dentate gyrus
• Cerebral cortex: Layers II-VI pyramidal neurons
• Cerebellum: Purkinje cells and granule cells
• Substantia nigra: Dopaminergic neurons
• White matter: Oligodendrocytes and myelin sheaths

Cellular Localization

ADAM8 is expressed in multiple brain cell types:

• Microglia: High expression in activated microglia surrounding amyloid plaques [@liu2020]
• Astrocytes: Moderate expression in reactive astrocytes
• Neurons: Expressed in pyramidal and other neuronal populations
• Oligodendrocytes: Present in pre-myelinating oligodendrocytes
• Endothelial cells: Expressed in blood-brain barrier endothelial cells [@chen2019]

Role in Neurodegenerative Diseases

Alzheimer's Disease

ADAM8 has significant implications for [Alzheimer's disease](/diseases/alzheimers-disease) pathogenesis [@yang2018]:

Amyloid Processing

• ADAM8 can cleave [APP](/proteins/app) at the alpha-site [@wang2021]
• May contribute to amyloid-beta generation
• Co-localizes with amyloid plaques in AD brain
• Genetic variants may modify AD risk

Neuroinflammation

• Significantly upregulated in AD brains [@martinez2023]
• Expressed at high levels in activated microglia surrounding plaques
• Promotes pro-inflammatory cytokine release (TNF-alpha, IL-6)
• Regulates microglial activation states

Tau Pathology

• ADAM8 expression correlates with tau pathology [@singh2022]
• May affect tau phosphorylation and aggregation
• Altered in brain regions with high tau burden

Blood-Brain Barrier

• ADAM8 affects BBB integrity in AD [@chen2019]
• May increase vascular permeability
• Contributes to vascular dysfunction

Therapeutic Implications

• ADAM8 inhibitors may reduce neuroinflammation
• Targeting microglial ADAM8 may provide benefit
• Combination approaches targeting amyloid and inflammation

Parkinson's Disease

ADAM8 contributes to [Parkinson's disease](/diseases/parkinsons-disease) through [@parks2021]:

Neuroinflammation

• Upregulated in PD substantia nigra
• Promotes microglial activation
• Contributes to dopaminergic neuron loss

Alpha-Synuclein Aggregation

• May interact with alpha-synuclein processing
• Affects protein aggregation pathways
• Contributes to Lewy body formation

Blood-Brain Barrier

• Disrupted BBB in PD
• ADAM8 may exacerbate vascular dysfunction

Other Neurodegenerative Conditions

ADAM8 is relevant to:

• Multiple sclerosis: Demyelination and immune cell infiltration
• Amyotrophic lateral sclerosis: Motor neuron vulnerability
• Huntington's disease: Protein aggregation and inflammation

Molecular Pathways

ADAM8 in Neuroinflammation

ADAM8 in Amyloid Processing

Signaling Pathways

ADAM8 participates in multiple signaling cascades:

| Pathway | Function | Neuronal Effect |
|---------|----------|----------------|
| NF-kB | Inflammatory signaling | Pro-inflammatory gene expression |
| MAPK/ERK | Cell proliferation/survival | Altered neuronal function |
| Notch | Neurogenesis | Impaired differentiation |
| EGFR | Growth factor signaling | Altered plasticity |
| Integrin | Cell adhesion | Migration and adhesion |

Therapeutic Implications

ADAM8 as Drug Target

ADAM8 represents a promising therapeutic target for neurodegenerative diseases [@kim2022]:

Small Molecule Inhibitors

• Metalloproteinase domain inhibitors
• Selective ADAM8 targeting compounds
• Brain-penetrant small molecules

Antibody-Based Therapies

• Anti-ADAM8 monoclonal antibodies
• Blocking antibodies for microglial ADAM8
• Engineered antibody fragments

Gene Therapy Approaches

Viral vector-mediated approaches are being explored [@taylor2023]:

• RNAi targeting: Reduce ADAM8 expression
• Dominant-negative: Block ADAM8 function
• Decoy receptors: Soluble ADAM8-Fc proteins

Therapeutic Strategies

• Microglial targeting: Specific targeting of microglial ADAM8
• Peripheral modulation: Targeting peripheral immune ADAM8
• Combination therapy: ADAM8 inhibition with amyloid-targeting

Challenges

• Selectivity: Avoiding off-target effects on other ADAMs
• Delivery: Getting inhibitors across the blood-brain barrier
• Timing: Optimal intervention in disease progression
• Biomarkers: Need for patient selection biomarkers

Research Directions

Current Knowledge Gaps

Emerging Research Areas

• Single-cell sequencing: ADAM8 expression in specific cell populations
• Structural studies: ADAM8-substrate complex structures
• Animal models: Conditional knockout in specific cell types
• Biomarkers: ADAM8 as disease biomarker or therapeutic target

Cross-Links

• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Neuroinflammation](/mechanisms/neuroinflammation)
• [Amyloid Cascade](/mechanisms/amyloid-cascade)
• [Blood-Brain Barrier](/entities/blood-brain-barrier)
• [Microglia](/cell-types/microglia)
• [Astrocytes](/cell-types/astrocytes)
• [TNF-alpha](/entities/tnf-alpha)
• [IL-6](/entities/il-6)
• [APP](/proteins/app)
• [Amyloid-beta](/proteins/amyloid-beta)

Key Publications

External Links

• [NCBI Gene: ADAM8](https://www.ncbi.nlm.nih.gov/gene/242)
• [UniProt: O43506](https://www.uniprot.org/uniprot/O43506)
• [Ensembl: ENSG00000151617](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000151617)
• [OMIM: 602432](https://www.omim.org/entry/602432)
• [GeneCards: ADAM8](https://www.genecards.org/cgi-bin/carddisp.pl?gene=ADAM8)

Pathway Diagram

The following diagram shows the key molecular relationships involving ADAM8 Gene discovered through SciDEX knowledge graph analysis: