FGF18 Gene

FGF18 — Fibroblast Growth Factor 18

Overview

FGF18 — Fibroblast Growth Factor 18

Overview

FGF18 (Fibroblast Growth Factor 18) is a member of the fibroblast growth factor (FGF) family that plays important roles in development, tissue repair, and nervous system function. As a paracrine signaling molecule, FGF18 binds to fibroblast growth factor receptors (FGFRs), particularly FGFR3 and FGFR2, to regulate cellular proliferation, differentiation, and survival. In the central nervous system, FGF18 has emerged as a significant regulator of neurogenesis, synaptic plasticity, and cognitive function, with growing evidence for its involvement in neurodegenerative diseases including Alzheimer's disease (AD) and Parkinson's disease (PD)[@kimura2021].

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Fibroblast Growth Factor 18</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>FGF18</td></tr>
<tr><td><strong>Full Name</strong></td><td>Fibroblast Growth Factor 18</td></tr>
<tr><td><strong>Chromosome</strong></td><td>5q33.1</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[2259](https://www.ncbi.nlm.nih.gov/gene/2259)</td></tr>
<tr><td><strong>OMIM</strong></td><td>[603726](https://omim.org/entry/603726)</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>[ENSG00000156427](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156427)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[O76093](https://www.uniprot.org/uniprot/O76093)</td></tr>
<tr><td><strong>Protein Length</strong></td><td>207 amino acids</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>[Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease)</td></tr>
</table>
</div>

Molecular Biology

Gene Structure and Expression

The FGF18 gene is located on chromosome 5q33.1 and consists of multiple exons encoding a 207-amino acid secreted protein. FGF18 is expressed in various tissues during development, with highest expression in bone, lung, and brain. In the adult brain, FGF18 is expressed in the hippocampus, cortex, and subventricular zone, where it regulates neural progenitor cell function and synaptic plasticity[@kimura2021].

Protein Structure

FGF18 is a member of the FGF18 subfamily of fibroblast growth factors. Like other FGFs, it contains a conserved beta-sheet rich core structure that mediates binding to FGFRs. The protein contains a signal peptide for secretion and undergoes limited post-translational modification. FGF18 exhibits high affinity for FGFR3 and FGFR2, with weaker binding to FGFR1 and FGFR4[@ornitz2015].

Signaling Mechanisms

FGF18 activates FGFR signaling through the following mechanisms:

• MAPK/ERK pathway: Regulates cell proliferation and differentiation
• PI3K/Akt pathway: Promotes cell survival
• PLCγ pathway: Modulates calcium signaling

Normal Function in the Brain

Neurogenesis

FGF18 plays a critical role in neural progenitor cell proliferation and differentiation:

• Subventricular zone: Maintains neural stem cell pools
• Hippocampal dentate gyrus: Supports granule cell neurogenesis
• Cortical development: Regulates cortical neuron production

Synaptic Plasticity

FGF18 modulates synaptic formation and function:

• Dendritic spine formation: Promotes spine development on pyramidal neurons
• Long-term potentiation (LTP): Enhances synaptic strengthening
• Learning and memory: Supports hippocampal-dependent cognitive function

Neuronal Survival

FGF18 provides trophic support for neurons:

• Anti-apoptotic signaling: Activates PI3K/Akt pathway
• Metabolic support: Promotes glucose metabolism
• Oxidative stress protection: Upregulates antioxidant defenses

Role in Neurodegenerative Diseases

Alzheimer's Disease

FGF18 is implicated in multiple aspects of AD pathogenesis:

Amyloid Processing

FGF18 signaling affects amyloid precursor protein (APP) processing:

• FGF signaling through FGFRs can reduce BACE1 expression
• Decreased BACE1 activity lowers amyloid-beta (Aβ) production
• FGF18 may promote non-amyloidogenic APP processing[@liu2022]

Neurogenesis Impairment

In AD, FGF18 expression is altered:

• Reduced FGF18 in hippocampus correlates with cognitive decline
• Impaired neurogenesis in dentate gyrus
• Decreased synaptic plasticity[@kimura2021]

Therapeutic Potential

FGF18-based therapies for AD include:

• Recombinant FGF18 protein administration
• Small molecule FGFR agonists
• Gene therapy to increase FGF18 expression

Parkinson's Disease

FGF18 may provide neuroprotection in PD:

Dopaminergic Neuron Survival

FGF18 supports tyrosine hydroxylase (TH) positive neurons:

• Promotes survival of dopaminergic neurons
• May protect against MPTP/6-OHDA toxicity
• Enhances neurotrophic factor expression

Alpha-Synuclein Interaction

FGF signaling intersects with alpha-synuclein pathology:

• May modulate protein aggregation pathways
• Supports autophagy-lysosome function
• Could reduce synuclein-induced toxicity[@schapansky2020]

Therapeutic Approaches

FGFR Agonists

Small molecule agonists that activate FGFRs (including FGFR3/FGFR2 targeted by FGF18):

| Compound | Target | Development Stage | Reference |
|----------|--------|-------------------|-----------|
| FGF18 protein | FGFR3/FGFR2 | Preclinical | [@fordpassanen2020] |
| FGFR agonist compounds | FGFR1-4 | Research | [@nakamachi2020] |

Gene Therapy

AAV-mediated FGF18 delivery:

• Target neurons in hippocampus and cortex
• Promote neurogenesis and synaptic function
• Currently in preclinical development

Combination Approaches

FGF18-based combination therapies:

• With cholinergic agents: Enhance cognitive function
• With anti-amyloid therapies: Address multiple disease pathways
• With neurotrophic factors: Synergistic neuroprotection

Expression Patterns

Brain Region Distribution

| Region | Expression Level | Function |
|--------|------------------|----------|
| Hippocampus (CA1-3) | High | Synaptic plasticity, memory |
| Dentate Gyrus | High | Neurogenesis |
| Cortex (Layers 2-3) | Moderate | Circuit formation |
| Subventricular Zone | Moderate | Neural stem cells |
| Cerebellum | Low | Motor learning |

Cellular Expression

• Neurons: Pyramidal cells, granule cells
• Astrocytes: Supporting cells
• Neural progenitor cells: Stem cell maintenance

Key Publications

See Also

• [FGF Signaling Pathway in Neurodegeneration](/mechanisms/fgf-signaling-neurodegeneration)
• [Neurogenesis](/cell-types/neurogenesis)
• [Neurotrophic Factors](/therapeutics/growth-factors)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [FGFR3 Gene](/genes/fgfr3)
• [FGFR1 Protein](/proteins/fgfr1-protein)

External Links

• [NCBI Gene: FGF18](https://www.ncbi.nlm.nih.gov/gene/2259)
• [Ensembl: ENSG00000156427](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156427)
• [UniProt: O76093](https://www.uniprot.org/uniprot/O76093)
• [OMIM: 603726](https://omim.org/entry/603726)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving FGF18 Gene discovered through SciDEX knowledge graph analysis: