adam9

adam9

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">adam9</th>
</tr>
<tr>
<td class="label">Identifier</td>
<td>Value</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>ADAM9</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>ADAM Metallopeptidase Domain 9</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>2247</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>602512</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000168615</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q13443</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>8p11.22</td>
</tr>
<tr>
<td class="label">Cell Type</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Neurons</td>
<td>High</td>
</tr>
<tr>
<td class="label">Astrocytes</td>
<td>High</td>
</tr>
<tr>
<td class="label">Microglia</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Oligodendrocytes</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Endothelial cells</td>
<td>Low-Moderate</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">Integrins</td>
<td>Disintegrin domain</td>
</tr>
<tr>
<td class="label">TIMP-3</td>
<td>Catalytic domain inhibition</td>
</tr>
<tr>
<td class="label">EGFR</td>
<td>Growth factor signaling</td

adam9

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">adam9</th>
</tr>
<tr>
<td class="label">Identifier</td>
<td>Value</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>ADAM9</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>ADAM Metallopeptidase Domain 9</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>2247</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>602512</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000168615</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q13443</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>8p11.22</td>
</tr>
<tr>
<td class="label">Cell Type</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Neurons</td>
<td>High</td>
</tr>
<tr>
<td class="label">Astrocytes</td>
<td>High</td>
</tr>
<tr>
<td class="label">Microglia</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Oligodendrocytes</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Endothelial cells</td>
<td>Low-Moderate</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">Integrins</td>
<td>Disintegrin domain</td>
</tr>
<tr>
<td class="label">TIMP-3</td>
<td>Catalytic domain inhibition</td>
</tr>
<tr>
<td class="label">EGFR</td>
<td>Growth factor signaling</td>
</tr>
<tr>
<td class="label">APP</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">Kit</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">NCAM</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

ADAM9 (A Disintegrin And Metalloproteinase 9) is a multifunctional member of the ADAM family of zinc-dependent metalloproteinases expressed throughout the body with particularly high levels in the brain. Located on chromosome 8p11.22, ADAM9 participates in diverse biological processes including cell adhesion, protein shedding, neurodevelopment, and synaptic function, with emerging relevance to [Alzheimer's Disease](/diseases/alzheimers-disease) (AD), [Parkinson's Disease](/diseases/parkinsons-disease) (PD), and cancer[1][2][3].

ADAM9 possesses catalytic metalloproteinase activity, functioning as an ectodomain "sheddase" that releases soluble extracellular domains from numerous membrane-bound substrates. This activity regulates signaling molecules, adhesion proteins, and disease-relevant proteins including [amyloid precursor protein](/proteins/app) (APP), positioning ADAM9 at the intersection of normal brain function and neurodegeneration[4][5].

Gene and Protein Structure

Gene Location and Organization

The ADAM9 gene is located on chromosome 8p11.22, spanning approximately 30 kb of genomic DNA. Key identifiers include:

The gene consists of 27 exons encoding an 819-amino acid type I transmembrane protein. Alternative splicing generates multiple transcript variants with tissue-specific expression patterns[1].

Protein Domain Architecture

ADAM9 contains the complete ADAM family domain structure:

Signal Prodomain Metalloproteinase Disintegrin Cysteine-rich EGF-like Transmembrane Cytoplasmic
peptide domain domain domain domain domain domain tail
↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓
[1-19] [20-207] [208-463] [464-605] [606-672] [673-705] [706-728] [729-819]

The metalloproteinase domain is catalytically active, distinguishing ADAM9 from catalytically inactive ADAMs like [ADAM23](/genes/adam23). This activity enables ADAM9 to function as an effective sheddase[6].

Biological Functions

Ectodomain Shedding

ADAM9 is a broad-spectrum sheddase releasing extracellular domains from numerous substrates[4][7]:

Growth Factor Processing

• Pro-EGF (pro-epidermal growth factor): Releases soluble EGF
• Pro-HB-EGF (heparin-binding EGF-like growth factor): Generates soluble HB-EGF
• Amphiregulin: Soluble form generated by ADAM9
• TGF-α (transforming growth factor alpha): Released for EGFR activation
• IGF-binding proteins (IGFBPs): Proteolytic release

Signaling Molecules

• Kit ligand (SCF): Soluble stem cell factor generation
• Jagged1: Notch ligand shedding
• FLT3 ligand: Hematopoietic growth factor release

Adhesion Molecules

• NCAM (Neural Cell Adhesion Molecule): Soluble form generation
• L1-CAM: Shedding affects neuronal migration
• CD44: Hyaluronic acid receptor shedding

APP Processing

ADAM9 can process [amyloid precursor protein](/proteins/app) (APP), releasing:

• sAPPα: Non-amyloidogenic cleavage product (alpha-secretase activity)
• sAPPβ: Amyloidogenic cleavage product (beta-secretase-like activity)
• Potential for both amyloidogenic and non-amyloidogenic processing[8]

Cell Adhesion

The disintegrin domain mediates cell-cell and cell-matrix adhesion:

Integrin Binding

ADAM9 interacts with multiple integrin subunits:

• α2β1: Collagen receptor
• α3β1: Laminin/collagen receptor
• α5β1: Fibronectin receptor
• α6β1: Laminin receptor
• αvβ3: Vitronectin receptor

Adhesive Functions

• Neuronal migration guidance
• Axon fasciculation
• Synapse formation and maintenance
• Neuron-glia interactions

Neurodevelopment

ADAM9 plays important roles in nervous system development[9]:

Synaptic Function

ADAM9 localizes to synapses where it regulates[10]:

Expression Pattern

Brain Expression

ADAM9 is widely expressed in the brain:

Regional Distribution

High expression in:

• Cerebral cortex (layers II-VI)
• Hippocampus (CA1, CA3, dentate gyrus)
• Cerebellum (Purkinje cells, granule cells)
• Basal ganglia
• Subventricular zone

Development

• Embryonic: Low expression, increasing with development
• Postnatal: Peak expression in early postnatal period
• Adult: Maintain moderate-high levels throughout life
• Aging: Increased expression in aged brain (cellular senescence)

Disease Associations

Alzheimer's Disease

ADAM9 is implicated in AD pathogenesis through multiple mechanisms[1][11][12]:

APP Processing

Synaptic Dysfunction

• Altered expression in AD brain[13]
• Reduced synaptic ADAM9 correlates with cognitive decline
• May affect synaptic protein composition

Neuroinflammation

ADAM9 in glial cells contributes to neuroinflammation[14]:

• Upregulated in reactive astrocytes (gliosis)
• Modulates cytokine and chemokine release
• May amplify neuroinflammatory responses

Cellular Senescence

Increased ADAM9 in aging and AD brains may reflect[15]:

• Cellular senescence phenotype
• Age-related transcriptional changes
• Stress response activation

Genetic Associations

Polymorphisms in the ADAM9 gene have been associated with:

• AD risk in some populations
• Age of onset modification
• Progression rates[16]

Parkinson's Disease

ADAM9 involvement in PD includes:

Cancer Biology

ADAM9 is frequently overexpressed in cancers:

• Pancreatic cancer: High expression, poor prognosis
• Lung cancer: Associated with metastasis
• Breast cancer: Promotes invasion
• Glioma: Correlates with grade

• Growth factor shedding (EGF, HB-EGF)
• Cell adhesion modulation
• Invasion and metastasis promotion

Cardiovascular Disease

• Atherosclerosis: ADAM9 in vascular smooth muscle cells
• Angiogenesis: Modulates endothelial cell function
• Restenosis: Post-injury vascular remodeling

Therapeutic Targeting

ADAM9 as Therapeutic Target

ADAM9 offers multiple therapeutic targeting opportunities[17][18]:

ADAM9 Inhibitors

• Broad-spectrum MMP/ADAM inhibitors
• Selective ADAM9 inhibitors in development

• Monoclonal antibodies
• Antibody fragments

• Flavonoids (e.g., luteolin, apigenin)
• Polyphenols (EGCG, resveratrol)

ADAM9 Activators

For AD, enhancing ADAM9 alpha-secretase activity could:

• Shift APP processing toward non-amyloidogenic pathway
• Reduce Aβ production
• Generate neuroprotective sAPPα

Drug Development Challenges

Signaling Pathways

Downstream Signaling

ADAM9 activates multiple intracellular pathways:

Regulation

ADAM9 activity is regulated by:

Molecular Interactions

Protein Partners

Animal Models

Knockout Mice

ADAM9 global knockout:

• Viable and fertile
• Mild neurological phenotypes
• Impaired wound healing
• Altered cardiovascular function

Transgenic Models

• ADAM9 overexpression: Enhanced tumor growth
• Conditional knockouts: Tissue-specific deletion
• Reporter lines: Expression pattern visualization

Disease Models

• ADAM9 in APP/PS1 mice: Cross with AD models
• ADAM9 in α-synuclein models: PD-related studies

Research Directions

Current Priorities

Emerging Approaches

• Single-cell analysis of ADAM9 expression
• Substrate profiling to understand specificity
• Cryo-EM structural studies
• Patient-derived models

Cross-Links

• [Alzheimer's Disease](/diseases/alzheimers-disease) - Primary disease context
• [Parkinson's Disease](/diseases/parkinsons-disease) - Related disease
• [APP Gene](/proteins/app) - Primary substrate
• [BACE1 Gene](/proteins/bace1-protein) - Competing amyloidogenic enzyme
• [Amyloid-beta](/proteins/amyloid-beta) - Disease-relevant fragment
• [ADAM10 Gene](/genes/adam10) - Related alpha-secretase
• [ADAM17 Gene](/genes/adam17) - Related ADAM family member
• [Neurons](/entities/neurons) - Primary cell type
• [Astrocytes](/entities/astrocytes) - Glial expression
• [Microglia](/cell-types/microglia-neuroinflammation) - Immune function

Summary

ADAM9 is a multifunctional metalloproteinase with diverse roles in normal physiology and disease. Its ability to shed numerous substrates including APP places it in a key position to influence amyloid processing, neuroinflammation, synaptic function, and cell survival. While ADAM9 can function as an alpha-secretase to potentially reduce Aβ production, it may also contribute to amyloidogenic processing under certain conditions. The enzyme's involvement in neuroinflammation through glial cells and its altered expression in aging and AD brains suggest it may play a complex role in disease pathogenesis. Understanding the precise contributions of ADAM9 to neurodegeneration and developing selective therapeutic modulators remain important research goals.

Mechanism Map

References