# FGF1 Gene: Structure, Function, and Clinical Significance


## Key Takeaways

- FGF1 is a pleiotropic growth factor with a canonical β-trefoil fold, acting as a pan-FGFR ligand that activates multiple downstream signaling pathways including MAPK, PI3K-AKT, and PLCγ-Ca²⁺, crucial for cell proliferation, survival, and differentiation.
- The *FGF1* gene exhibits complex transcriptional regulation via at least four distinct tissue-specific promoters (1A, 1B, 1C, 1G), allowing for precise spatiotemporal control of expression, with key transcription factors like RFX1 and CRTC1 playing critical roles in neural and other cell types.
- FGF1 plays a significant role in metabolic regulation, demonstrating potent antidiabetic effects via hypothalamic modulation and hepatic glucokinase upregulation, and is essential for neurogenesis and memory consolidation, particularly through the CRTC1-FGF1 axis in the hippocampus.
- Aberrant FGF1 expression, including gene amplification and fusion events (e.g., FN1-FGF1 in phosphaturic mesenchymal tumors), is implicated in various cancers, driving tumor progression through autocrine/paracrine signaling, while germline polymorphisms are associated with diseases like Alzheimer's and non-syndromic cleft lip/palate.
- FGF1's therapeutic potential is being explored through recombinant protein therapy and gene delivery for conditions like myocardial ischemia and peripheral artery disease, while FGFR tyrosine kinase inhibitors represent a class of FDA-approved drugs indirectly targeting FGF1 signaling in cancers such as cholangiocarcinoma and urothelial carcinoma.

---

## Executive Summary & Key Metadata

| Attribute | Value |
|---|---|
| **HGNC Symbol** | FGF1 |
| **UniProt Accession** | P05230 |
| **Representative PDB ID** | 1RG8 (also 1JQZ, 2AFG, 3BAF) |
| **Chromosomal Locus** | 5q31.3–q32 |
| **Primary Molecular Function** | Growth factor; mitogenic and angiogenic signaling via FGFR tyrosine kinase receptors; heparin-binding ligand |
| **Disease & Pathology Associations** | Atherosclerosis, Alzheimer's disease, multiple cancers (breast, hepatocellular, renal cell, colorectal, nasopharyngeal, ovarian), type 2 diabetes, osteoarthritis, non-syndromic cleft lip/palate, essential hypertension, tendinopathy, phosphaturic mesenchymal tumors (via FN1–FGF1 fusion) |
| **Expression Pattern** | Broad; highest in brain, kidney, heart, and adipose tissue; multiple tissue-specific promoters drive context-dependent expression |
| **Protein Length** | 155 amino acids (mature form; 153 aa after signal peptide cleavage in some isoforms) |
| **Molecular Weight** | ~17.5 kDa (canonical isoform) |

---

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Genomic Architecture

The human *FGF1* gene is located on the long arm of chromosome 5 at cytogenetic band 5q31.3–q32. This region is notable for its gene density and its association with several disease loci, including a tumor suppressor region implicated in acute non-lymphocytic leukemia/myelodysplastic syndrome (ANLL/MDS). Early work using yeast artificial chromosome (YAC) contigs established that the entire transcriptional unit of *FGF1* spans approximately 720 kb of genomic DNA, making it one of the larger growth factor genes in the human genome. This substantial genomic footprint arises from the presence of multiple upstream non-coding exons distributed over a large regulatory landscape.

The *FGF1* gene is oriented on the plus strand and comprises at least four alternative promoters (designated 1A, 1B, 1C, and 1G) that each drive transcription of a distinct untranslated first exon. These promoter regions are separated by large intronic distances, with the 1B promoter located approximately 100 kb upstream of the coding exons and the 1A promoter even further upstream. The 1G promoter, which is the most recently characterized, is situated in a GC-rich region and is active in a variety of cell types.

### 1.2 Promoter Architecture and Regulatory Elements

The *FGF1* gene is regulated by multiple tissue-specific promoters, a feature that permits precise spatiotemporal control of expression across diverse physiological contexts. Each promoter exhibits distinct cis-regulatory architecture:

**1A Promoter:** Active predominantly in the kidney and heart. Contains binding sites for the transcription factor RFX1, which has been shown to regulate FGF1 expression in a ciliogenic context. The 1A promoter also responds to signaling through Aurora-A kinase, sustaining self-renewal of embryonic and neural stem cells.

**1B Promoter:** The best-characterized promoter, active in the brain, retina, and spinal cord. The 1B promoter region spanning −540 to +31 relative to the transcription start site has been used to drive GFP expression in transgenic reporter systems (F1B-GFP mice), enabling the isolation of neural stem/progenitor cells with self-renewal and multipotent capacities. This promoter contains functional RFX1 binding sites that are critical for its activity in neural tissues. Additionally, the 1B promoter is responsive to valproate, a mood stabilizer, through mechanisms involving HDAC and GSK-3 inhibition. The transcription factor CRTC1, which translocates to the nucleus following learning-related synaptic activity, binds the 1B promoter and exchanges chromatin remodeling complexes to modulate FGF1 expression and memory strength.

**1C Promoter:** Active in vascular smooth muscle cells and other mesenchymal lineages. This promoter is regulated by the transcription factor SOX9, which is acetylated by GCN5 in response to sublytic C5b-9 complement attack in glomerular mesangial cells.

**1G Promoter:** A GC-rich promoter active in many cell types, including embryonic stem cells. It is regulated by RFX transcription factors and contributes to basal FGF1 expression.

### 1.3 Transcription Factor Binding Sites and Enhancer Elements

Chromatin immunoprecipitation and reporter assays have identified several key transcription factors that bind the *FGF1* promoters:

- **RFX1:** Binds the 1B promoter and activates transcription in neural progenitor cells. RFX1 acetylation by KAT7 is required for its transcriptional activity; loss of NgBR (encoded by *NUS1*) reduces KAT7-mediated RFX1 acetylation, leading to decreased FGF1 expression and neuronal damage in Parkinson's disease models.
- **CRTC1:** A CREB co-activator that translocates to the nucleus upon synaptic stimulation. CRTC1 binds the 1B promoter and recruits the BAF (SWI/SNF) chromatin remodeling complex, exchanging it with the repressive NCoR complex to activate FGF1 transcription. This mechanism underlies the role of FGF1 in memory consolidation and fear memory persistence.
- **SOX9:** Acetylated by GCN5 in response to sublytic C5b-9, SOX9 binds the 1C promoter and drives FGF1 expression in mesangial cell proliferation.
- **LHX2:** A LIM-homeodomain transcription factor that binds the FGF1 promoter and activates transcription in nasopharyngeal carcinoma cells, promoting autocrine FGF1/FGFR signaling.
- **Aurora-A Kinase:** Signaling through Aurora-A activates the 1A and 1B promoters, sustaining stem cell self-renewal.
- **WNT7A/β-catenin:** In ovarian cancer, WNT7A/β-catenin signaling induces FGF1 expression, linking developmental signaling pathways to tumor progression.

### 1.4 Alternative Splicing and Isoforms

Alternative splicing of the *FGF1* gene generates multiple mRNA variants that share the same protein-coding exons but differ in their 5' untranslated regions (UTRs). The protein-coding region is contained within three exons (exons 2, 3, and 4 in the genomic structure), which are spliced to one of the alternative first exons (1A, 1B, 1C, or 1G). This arrangement produces mRNAs with identical open reading frames but distinct 5' UTRs, allowing for differential translational regulation and tissue-specific expression.

The canonical FGF1 protein is 155 amino acids in length, though some isoforms lack the N-terminal signal peptide and are localized intracellularly or released through non-classical secretory pathways. The protein lacks a conventional signal sequence in most isoforms, and its secretion occurs via an endoplasmic reticulum/Golgi-independent pathway that involves the Na+/K+-ATPase and the membrane protein S100A13.

### 1.5 Polymorphisms and Regulatory Variants

Several single nucleotide polymorphisms (SNPs) in the *FGF1* gene have been associated with human disease:

- **rs34011 (G/A):** Located in the promoter region, this polymorphism has been associated with Alzheimer's disease risk. The A allele is associated with altered FGF1 expression levels in the brain.
- **−1385 A/G promoter polymorphism:** Associated with Alzheimer's disease, with parent-of-origin effects reported.
- **rs152524:** Associated with metabolic risk factors including obesity and dyslipidemia in a gender-dependent manner.
- **FGF1 gene variants in non-syndromic cleft lip/palate:** Multiple studies have identified associations between FGF1 SNPs and NSCL/P risk in diverse populations, including Polish, Iranian, and Chinese cohorts.
- **FGF1 polymorphisms in essential hypertension:** Positional cloning and expression analysis identified FGF1 as a candidate gene for essential hypertension, with specific SNPs associated with blood pressure regulation.

---

## 2. 3D Protein Domain Architecture & Structural Biology

### 2.1 Overall Fold and Domain Organization

FGF1 adopts the canonical β-trefoil fold characteristic of the fibroblast growth factor family. The protein consists of 12 antiparallel β-strands arranged in three repeating units of four strands each, forming a six-stranded β-barrel capped by three β-hairpin loops. This fold creates a triangular, barrel-like structure with approximate dimensions of 40 × 30 × 30 Å.

The β-trefoil architecture of FGF1 can be divided into three structural repeats (I, II, and III), each comprising four β-strands (β1–β4, β5–β8, and β9–β12, respectively). The strands within each repeat are connected by loops of varying lengths, with the longest loops (between β4–β5, β8–β9, and β12–β1) forming the "top" of the molecule that interacts with the FGFR receptor.

### 2.2 Domain Boundaries and Functional Regions

**N-terminal region (residues 1–20):** This region is flexible and largely disordered in crystal structures. It contains the nuclear localization signal (NLS) at residues 21–27 (NYKKPKL), which mediates translocation to the nucleus in response to stress or growth stimuli. The N-terminus also contains a heparin-binding site that contributes to the high-affinity interaction with heparan sulfate proteoglycans (HSPGs).

**Core β-trefoil domain (residues 21–140):** This region constitutes the structural scaffold of the protein and contains the receptor-binding surface. Key residues involved in FGFR binding include:

- **Receptor-binding site 1 (high-affinity site):** Comprises residues from β-strands β4, β5, and β10–β11, including Tyr97, Arg118, and Leu149. This site interacts with the immunoglobulin-like domain D3 of FGFR.
- **Receptor-binding site 2 (low-affinity site):** Involves residues from the β1–β2 loop and the β8–β9 loop, including Asn32, Lys118, and Gln127. This site contacts the D2 domain of FGFR.
- **Heparin-binding site:** A cluster of basic residues (Lys112, Lys113, Arg116, Lys118, and Arg122) located on the surface of the β-trefoil domain. Heparin binding induces conformational changes that promote FGFR dimerization and signaling.

**C-terminal region (residues 141–155):** This short C-terminal tail is partially disordered and contributes to protein stability. It contains a second nuclear localization signal and is the site of several post-translational modifications.

### 2.3 Post-Translational Modifications

FGF1 undergoes several post-translational modifications that modulate its activity:

- **Phosphorylation:** FGF1 can be phosphorylated on serine and tyrosine residues, although the functional consequences are not fully characterized.
- **Cysteine oxidation:** The single cysteine residue (Cys117) is sensitive to oxidation and can form disulfide-linked dimers or undergo S-nitrosylation, affecting protein stability and secretion.
- **Proteolytic processing:** FGF1 can be cleaved by proteases to generate truncated forms with altered receptor-binding properties.

### 2.4 Structural Basis of FGFR Binding

The interaction between FGF1 and its receptors (FGFR1–FGFR4) is mediated by a two-site binding mechanism. The primary binding site on FGF1 interacts with the D3 domain of FGFR, while a secondary site interacts with the D2 domain. Heparin or heparan sulfate proteoglycans bridge the FGF1-FGFR complex by binding to basic residues on both proteins, stabilizing the signaling complex and promoting FGFR dimerization.

The FGF1-FGFR interaction is characterized by high affinity (Kd in the low nanomolar range) and is modulated by the presence of heparin, which increases the affinity by approximately 10-fold. Structural studies have revealed that FGF1 binding induces conformational changes in FGFR that promote receptor dimerization and trans-autophosphorylation of tyrosine residues in the intracellular kinase domain.

### 2.5 Interactive 3D Visualization

[Interactive 3D Protein Visualizer: Load FGF1 (PDB: 1RG8)](/tools/protein-structure-viewer?source=direct&pdbId=1RG8)

The interactive visualizer allows exploration of the FGF1 β-trefoil structure, including the receptor-binding surfaces, heparin-binding site, and nuclear localization signal. Users can rotate the molecule, color by residue conservation or hydrophobicity, and overlay structural alignments with FGF2 and other family members.

---

## 3. Cellular Signaling Pathways & Molecular Function

### 3.1 FGF1 as a Pleiotropic Growth Factor

FGF1 (acidic fibroblast growth factor, aFGF) is a member of the FGF family of signaling proteins that regulate diverse biological processes including embryonic development, angiogenesis, neurogenesis, tissue repair, and metabolism. Unlike most FGF family members, FGF1 can bind and activate all seven principal FGFR isoforms (FGFR1b, FGFR1c, FGFR2b, FGFR2c, FGFR3b, FGFR3c, FGFR4), making it a pan-FGFR ligand with broad target cell specificity.

### 3.2 Canonical FGFR Signaling Pathway

The canonical FGF1 signaling cascade is initiated by the binding of FGF1 to FGFR in a complex with heparan sulfate proteoglycans (HSPGs). This ternary complex induces FGFR dimerization and trans-autophosphorylation of specific tyrosine residues in the intracellular kinase domain. The phosphorylated receptor then recruits adaptor proteins and activates downstream signaling cascades:

```mermaid
sequenceDiagram
    participant FGF1
    participant HSPG
    participant FGFR
    participant FRS2
    participant GRB2
    participant SOS
    participant RAS
    participant RAF
    participant MEK
    participant ERK
    participant Nucleus

    FGF1->>FGFR: Ligand binding (with HSPG)
    HSPG->>FGFR: Stabilizes complex
    FGFR->>FGFR: Dimerization & autophosphorylation
    FGFR->>FRS2: Phosphorylation of FRS2 (Y196, Y306, Y349)
    FRS2->>GRB2: Recruitment via SH2 domain
    GRB2->>SOS: Recruitment via SH3 domain
    SOS->>RAS: GDP→GTP exchange
    RAS->>RAF: Activation (membrane recruitment)
    RAF->>MEK: Phosphorylation (S218/S222)
    MEK->>ERK: Phosphorylation (T202/Y204)
    ERK->>Nucleus: Translocation & transcription factor activation
    Nucleus-->>FGF1: Transcriptional feedback (e.g., via CRTC1, RFX1)
```

**Key downstream pathways activated by FGF1:**

1. **RAS-MAPK Pathway:** FGF1 binding activates the RAS-RAF-MEK-ERK cascade, which regulates cell proliferation, differentiation, and survival. In chondrocytes, FGF1 signaling through this pathway has been shown to inhibit proliferation, and phosphoproteomic analysis has identified a distinct inhibitory signature involving ERK1/2 phosphorylation.

2. **PI3K-AKT Pathway:** FGF1 activates phosphoinositide 3-kinase (PI3K), leading to AKT phosphorylation and activation of downstream targets including mTOR and FOXO transcription factors. This pathway promotes cell survival and metabolism.

3. **PLCγ-Ca²⁺ Pathway:** FGF1 binding activates phospholipase Cγ (PLCγ), which hydrolyzes phosphatidylinositol 4,5-bisphosphate to generate inositol trisphosphate (IP3) and diacylglycerol (DAG). IP3 triggers calcium release from intracellular stores, while DAG activates protein kinase C (PKC). PKC signaling is particularly important for FGF1-mediated cardiogenesis.

4. **STAT Pathway:** FGF1 can activate signal transducers and activators of transcription (STATs), particularly STAT3, which regulates gene expression involved in cell survival and inflammation.

### 3.3 Non-Canonical Signaling and Intracellular FGF1

In addition to its classical role as a secreted growth factor, FGF1 can translocate to the nucleus via its NLS and exert direct effects on gene expression. Nuclear FGF1 has been implicated in the regulation of ribosomal DNA transcription and cell cycle progression. This intracellular function is particularly relevant in stressed cells, where FGF1 is released from the cytoplasm and accumulates in the nucleus.

### 3.4 FGF1 in Metabolic Regulation

FGF1 has emerged as a critical regulator of glucose and lipid metabolism. A single intracerebroventricular (icv) injection of FGF1 induces sustained remission of hyperglycemia in rodent models of type 2 diabetes, an effect that lasts for weeks. The antidiabetic action of FGF1 involves:

- **Hypothalamic AgRP neurons:** FGF1 induces a shift in transcriptionally distinct AgRP neuron subpopulations, reducing the overactivity characteristic of diabetic states.
- **Parabrachial CGRP neurons:** FGF1-induced anorexia is mediated by activation of CGRP neurons in the parabrachial nucleus.
- **Hepatic glucokinase:** FGF1 upregulates glucokinase (GCK) expression and increases lactate export in hepatocytes, promoting glucose utilization.
- **Peripheral mechanisms:** FGF1's sustained antidiabetic action involves increased insulin sensitivity and improved β-cell function.

### 3.5 FGF1 in Neurogenesis and Memory

FGF1 is highly expressed in the adult brain, particularly in the hippocampus and cortex, where it supports neurogenesis and synaptic plasticity. The transcription factor CRTC1, which translocates to the nucleus following learning-related synaptic activity, binds the FGF1 1B promoter and modulates FGF1 expression. This CRTC1-FGF1 axis is required for memory consolidation and the persistence of fear memory.

FGF1 signaling is also critical for the survival and differentiation of neural stem/progenitor cells. The 1B promoter of FGF1 has been used to isolate neural stem cells with self-renewal and multipotent capacities, and FGF1 overexpression in adipose-derived mesenchymal stem cells induces neuroprotection and functional recovery in a rat stroke model.

### 3.6 FGF1 in Angiogenesis and Vascular Biology

FGF1 is a potent angiogenic factor that promotes endothelial cell proliferation, migration, and tube formation. It plays a critical role in:

- **Endothelial progenitor cell function:** miR-361-5p regulates EPC viability, migration, and tube formation by targeting FGF1. Downregulation of miR-361-5p promotes EPC function via FGF1 upregulation.
- **Vascular smooth muscle cell proliferation:** miR-188-3p inhibits VSMC proliferation and migration by targeting FGF1, suggesting a role in atherosclerosis.
- **Atherosclerosis:** TUG1 knockdown ameliorates atherosclerosis by upregulating miR-133a, which targets FGF1. This regulatory axis represents a potential therapeutic target for cardiovascular disease.
- **Therapeutic angiogenesis:** Autologous transplantation of endothelial progenitor cells encoding the FGF1 gene promotes neovascularization in a porcine model of chronic myocardial ischemia. Non-viral FGF1 gene transfer has been evaluated for safety in peripheral artery disease.

### 3.7 FGF1 in Skeletal Development and Osteogenesis

FGF1 signaling is essential for skeletal development and bone homeostasis. In osteogenic progenitors derived from neural crest, FGF1 expression is associated with RUNX2, a master regulator of osteoblast differentiation. FGF1 signaling protects against tendinopathic changes through sensory nerve innervation, and FGF1 has been identified as a diagnostic biomarker and RAS-MAPK-driven pathogenic factor in osteoarthritis.

### 3.8 Protein-Protein Interaction Networks

FGF1 interacts with a diverse array of proteins beyond its canonical receptors:

- **FGFR1–FGFR4:** High-affinity receptor tyrosine kinases.
- **Heparan sulfate proteoglycans (HSPGs):** Syndecans, glypicans, and perlecan.
- **S100A13:** A calcium-binding protein involved in FGF1 secretion.
- **Synaptotagmin-1:** Involved in FGF1 release from cells.
- **Na+/K+-ATPase:** Mediates FGF1 translocation across the plasma membrane.
- **Fibronectin (FN1):** In phosphaturic mesenchymal tumors, FN1-FGF1 fusion proteins are generated by chromosomal rearrangements.

---

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

### 4.1 Somatic Mutations and Gene Alterations in Cancer

**Gene Amplification:** FGF1 gene amplification has been reported in various cancers, including breast cancer and head and neck squamous cell carcinoma. Amplification leads to overexpression of FGF1, promoting autocrine/paracrine signaling through FGFRs and driving tumor progression.

**Gene Fusions:** The FN1-FGF1 fusion gene has been identified in phosphaturic mesenchymal tumors (PMTs). This fusion results from a chromosomal translocation that juxtaposes the fibronectin (FN1) gene with FGF1, generating a chimeric protein with constitutive FGF1 activity. The FN1-FGF1 fusion is mutually exclusive with FN1-FGFR1 fusions and is associated with tumor-induced osteomalacia due to FGF23 secretion.

**Gene Mutations:** While FGF1 is not a classic oncogene with recurrent activating mutations, somatic mutations have been described in various cancers. These mutations are typically loss-of-function or neutral, reflecting the complex role of FGF1 in tumor biology where both overexpression and downregulation can contribute to malignancy depending on context.

### 4.2 Germline Polymorphisms and Disease Associations

**Alzheimer's Disease:** The rs34011 (G/A) polymorphism in the FGF1 gene has been associated with Alzheimer's disease risk. The −1385 A/G promoter polymorphism also shows association with AD, with parent-of-origin effects. These polymorphisms may affect FGF1 expression levels in the brain, influencing neuronal survival and synaptic plasticity.

**Non-Syndromic Cleft Lip/Palate:** Multiple studies have identified associations between FGF1 gene variants and NSCL/P risk. The FGF1 gene is part of the FGF/FGFR signaling pathway critical for craniofacial development, and polymorphisms that alter FGF1 expression or function may disrupt palatal fusion.

**Essential Hypertension:** Positional cloning identified FGF1 as a candidate gene for essential hypertension. FGF1 expression in the kidney and vasculature may influence blood pressure through effects on vascular tone and sodium handling.

**Psoriatic Arthritis:** Polymorphisms in FGF1, along with VEGF, FGF2, and EGF, have been studied for association with psoriatic arthritis. Angiogenesis is a first-order event in PsA, and FGF1 contributes to the angiogenic drive.

**Endometriosis:** Genetic variants of FGF1 have been associated with endometriosis in Iranian women.

**Cerebral Infarction:** FGF-related gene polymorphisms, including FGF1, have been associated with cerebral infarction risk in patients treated with direct oral anticoagulants.

### 4.3 Differential Expression in Disease

**Clear Cell Renal Cell Carcinoma:** Bioinformatic analysis has identified FGF1 as a new prognostic indicator in ccRCC. High FGF1 expression is associated with poor prognosis, and FGF1 may serve as a therapeutic target.

**Hepatocellular Carcinoma:** miR-143-3p inhibits proliferation and invasion of HCC cells by regulating FGF1. FGF1 overexpression promotes HCC progression through autocrine FGFR signaling.

**Colorectal Cancer:** FGF1 is aberrantly expressed in CRC and is associated with mTOR-S6K1 signaling. Loss of AKR1B10 promotes CRC proliferation and migration via FGF1-dependent pathways. COX4I2 acts through FGF1 to promote EMT and angiogenesis in CRC.

**Breast Cancer:** FGF1 is differentially expressed in tumors of breast cancer patients treated with trastuzumab. FGF1 regulates breast cancer growth and metabolic reprogramming through ETV4. Gene-based analysis identified FGF1 as associated with estrogen receptor-negative breast cancer risk. FGF1 gene variants are associated with breast cancer risk and survival. The lncRNA MORT negatively regulates FGF1 to suppress malignant progression of breast cancer.

**Nasopharyngeal Carcinoma:** LHX2 transcriptionally regulates FGF1 and promotes cancer progression through activating the FGF1/FGFR axis. β-eudesmol inhibits NPC cell growth and enhances chemosensitivity by targeting FGF1/FGFR signaling.

**Ovarian Cancer:** WNT7A/β-catenin signaling induces FGF1 and influences sensitivity to niclosamide in ovarian cancer. Individuality in FGF1 expression significantly influences platinum resistance and progression-free survival.

**Gastric Cancer:** FGF1 is part of a seven immune-related gene prognostic signature for gastric cancer.

**Oral Cavity Squamous Cell Carcinoma:** Notch signaling activation is associated with patient mortality and increased FGF1-mediated invasion.

**Pancreatic Cancer:** Sodium new houttuyfonate affects tumor angiogenesis by suppressing FGF1 expression and the p38/MAPK signaling pathway.

### 4.4 FGF1 in Metabolic and Neurodegenerative Diseases

**Type 2 Diabetes:** FGF1 is a potent antidiabetic agent when administered centrally. The mechanism involves modulation of AgRP neuron subpopulations and peripheral effects on glucose metabolism.

**Parkinson's Disease:** Loss of NgBR causes neuronal damage through decreasing KAT7-mediated RFX1 acetylation and FGF1 expression. FGF1 may serve as a neuroprotective factor in PD.

**Addiction:** Prefrontal FGF1 signaling is required for accumbal deep brain stimulation treatment of addiction.

**Liver Disease:** FGF1 signaling modulates biliary injury and liver fibrosis in primary sclerosing cholangitis. Endogenous FGF1 deficiency aggravates doxorubicin-induced hepatotoxicity. CircZBTB46 alleviates metabolic dysfunction-associated steatotic liver disease by targeting the miRNA-326/FGF1 axis.

**Tendinopathy:** Sensory nerves protect against preclinical tendinopathic changes through FGF1 signaling.

---

## 5. Host-Pathogen & Viral Interactions

### 5.1 Viral Interactions with FGF1

While FGF1 is not a direct target of viral oncoproteins in the same manner as p53 or Rb, several viruses modulate FGF1 expression or signaling to promote their life cycle or induce pathology:

**Human Papillomavirus (HPV):** In head and neck squamous cell carcinomas, FGF1 DNA methylation is associated with HPV status. HPV-positive tumors show distinct FGF1 methylation patterns that correlate with transcriptional activity and sensitivity to tyrosine kinase inhibitors.

**Hepatitis Viruses:** In hepatocellular carcinoma, FGF1 expression is dysregulated, and viral hepatitis may contribute to this through chronic inflammation and epigenetic modifications.

### 5.2 Bacterial Interactions

**Helicobacter pylori:** Chronic H. pylori infection can lead to gastric cancer, and FGF1 expression is altered in gastric cancer. While direct interactions between H. pylori effectors and FGF1 have not been demonstrated, the inflammatory microenvironment induced by H. pylori may influence FGF1 expression.

### 5.3 Immune Evasion Mechanisms

FGF1 contributes to tumor immune evasion through multiple mechanisms:

- **Angiogenesis:** FGF1 promotes tumor vascularization, which can impair immune cell infiltration.
- **Immunosuppressive microenvironment:** FGF1 signaling can promote the recruitment of immunosuppressive cells, including regulatory T cells and myeloid-derived suppressor cells.
- **Resistance to immune checkpoint inhibitors:** FGF1 overexpression may contribute to resistance to anti-PD-1/PD-L1 therapy by promoting an immunosuppressive tumor microenvironment.

### 5.4 Complement-Mediated Regulation

Sublytic C5b-9 complement attack triggers FGF1 gene transcription in glomerular mesangial cells through GCN5-dependent SOX9 acetylation. This represents a host-pathogen-like interaction where the complement system, part of the innate immune response, directly regulates FGF1 expression.

---

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

### 6.1 FGF1 as a Therapeutic Target

Given its role in angiogenesis, cell proliferation, and metabolism, FGF1 is an attractive therapeutic target for multiple diseases. However, its broad expression and pleiotropic functions present challenges for targeted therapy.

### 6.2 FDA-Approved Drugs Affecting FGF1 Signaling

While no drugs directly target FGF1 itself, several FDA-approved agents modulate FGF1/FGFR signaling:

**FGFR Tyrosine Kinase Inhibitors (TKIs):**

| Drug | Target | Indication | Mechanism |
|---|---|---|---|
| **Erdafitinib (Balversa)** | FGFR1–4 | Metastatic urothelial carcinoma | ATP-competitive TKI |
| **Pemigatinib (Pemazyre)** | FGFR1–3 | Cholangiocarcinoma | Selective FGFR1–3 inhibitor |
| **Infigratinib (Truseltiq)** | FGFR1–3 | Cholangiocarcinoma | Selective FGFR1–3 inhibitor |
| **Futibatinib (Lytgobi)** | FGFR1–4 | Cholangiocarcinoma | Irreversible FGFR1–4 inhibitor |

These agents indirectly target FGF1 signaling by inhibiting the receptor tyrosine kinases that FGF1 activates.

### 6.3 Investigational Agents Targeting FGF1

**FGF1 Protein Therapy:** Recombinant FGF1 has been investigated for therapeutic angiogenesis in cardiovascular disease. Non-viral FGF1 gene transfer has been evaluated for safety in peripheral artery disease. Intramuscular gene transfer of non-viral FGF1 was well-tolerated with no significant adverse events.

**FGF1 Gene Therapy:** Adenoviral and plasmid-based FGF1 gene delivery has been studied for:

- **Myocardial ischemia:** Autologous transplantation of EPCs encoding FGF1 promotes neovascularization in chronic myocardial ischemia.
- **Peripheral artery disease:** Non-viral FGF1 gene transfer shows long-term safety.
- **Stroke:** FGF1-overexpressing adipose-derived mesenchymal stem cells induce neuroprotection and functional recovery.

**Small-Molecule Inhibitors of FGF1:**

- **β-eudesmol:** A natural compound that inhibits NPC cell growth and enhances chemosensitivity by targeting FGF1/FGFR signaling.
- **Sodium new houttuyfonate (SNH):** Suppresses FGF1 expression and p38/MAPK signaling in pancreatic cancer.
- **Niclosamide:** Sensitivity to niclosamide in ovarian cancer is influenced by WNT7A/β-catenin-induced FGF1 expression.

### 6.4 MicroRNA-Based Therapeutics

Multiple microRNAs regulate FGF1 expression and represent potential therapeutic targets:

| miRNA | Effect on FGF1 | Disease Context | Reference |
|---|---|---|---|
| **miR-133a** | Downregulates FGF1 | Atherosclerosis | |
| **miR-143-3p** | Downregulates FGF1 | Hepatocellular carcinoma | |
| **miR-361-5p** | Downregulates FGF1 | Deep venous thrombosis | |
| **miR-188-3p** | Downregulates FGF1 | Atherosclerosis | |
| **miR-143** | Downregulates FGF1 | Endothelial differentiation | |
| **miR-21** | Downregulates FGF1 | Chondrocyte regulation | |
| **miR-18a** | Downregulates FGF1 | Myoblast proliferation | |
| **miR-326** | Downregulates FGF1 | MASLD | |

### 6.5 Long Non-Coding RNA Therapeutics

LncRNAs that regulate FGF1 expression include:

- **TUG1:** Sponges miR-133a to regulate FGF1 in atherosclerosis and sponges miR-143 to enhance endothelial differentiation.
- **MORT:** Negatively regulates FGF1 to suppress breast cancer progression.
- **Gas5:** Regulates FGF1 expression via miR-21 in growth plate chondrocytes.
- **CircZBTB46:** Targets the miRNA-326/FGF1 axis in MASLD.

### 6.6 Pharmacogenomic Considerations

FGF1 gene polymorphisms may influence drug response:

- **FGF1 expression and platinum resistance:** Individuality in FGF1 expression significantly influences platinum resistance and progression-free survival in ovarian cancer.
- **FGF1 methylation and TKI sensitivity:** FGF1 DNA methylation in HNSCC is associated with sensitivity to tyrosine kinase inhibitors.
- **FGF1 polymorphisms and anticoagulant response:** FGF-related gene polymorphisms are associated with cerebral infarction in patients treated with direct oral anticoagulants.

---

## 7. Bioinformatic Resources & Database Accessions

### 7.1 Primary Database Accessions

| Database | Accession/ID | Description |
|---|---|---|
| **NCBI Gene** | 2246 | FGF1 gene |
| **Ensembl** | ENSG00000113578 | FGF1 gene |
| **UniProt** | P05230 | FGF1 protein |
| **RCSB PDB** | 1RG8, 1JQZ, 2AFG, 3BAF | FGF1 crystal structures |
| **OMIM** | 131220 | FGF1 gene |
| **HGNC** | 3663 | FGF1 symbol |
| **RefSeq (mRNA)** | NM_000800 | FGF1 transcript variant 1 |
| **RefSeq (Protein)** | NP_000791 | FGF1 protein isoform 1 |
| **ClinVar** | Multiple | FGF1 variants |
| **COSMIC** | Multiple | FGF1 somatic mutations |
| **STRING** | P05230 | FGF1 protein-protein interactions |
| **BioGRID** | 109217 | FGF1 interactions |
| **PharmGKB** | PA28126 | FGF1 pharmacogenomics |
| **GTEx** | ENSG00000113578 | FGF1 expression across tissues |
| **Human Protein Atlas** | ENSG00000113578 | FGF1 protein expression |

### 7.2 Gene Ontology (GO) Terms

| Category | GO Term | Description |
|---|---|---|
| **Molecular Function** | GO:0008083 | Growth factor activity |
| **Molecular Function** | GO:0008201 | Heparin binding |
| **Molecular Function** | GO:0005104 | Fibroblast growth factor receptor binding |
| **Molecular Function** | GO:0042802 | Identical protein binding |
| **Biological Process** | GO:0008284 | Positive regulation of cell proliferation |
| **Biological Process** | GO:0001525 | Angiogenesis |
| **Biological Process** | GO:0008543 | Fibroblast growth factor receptor signaling pathway |
| **Biological Process** | GO:0045664 | Regulation of neuron differentiation |
| **Biological Process** | GO:0007613 | Memory |
| **Biological Process** | GO:0032868 | Response to insulin |
| **Biological Process** | GO:0006091 | Generation of precursor metabolites and energy |
| **Cellular Component** | GO:0005576 | Extracellular region |
| **Cellular Component** | GO:0005634 | Nucleus |
| **Cellular Component** | GO:0005829 | Cytosol |

### 7.3 Expression Data

FGF1 is broadly expressed across human tissues, with highest expression in:

- **Brain:** Particularly in the hippocampus, cortex, and cerebellum
- **Kidney:** High expression in renal tubular cells
- **Heart:** Expressed in cardiomyocytes and cardiac fibroblasts
- **Adipose tissue:** Expressed in both white and brown adipose tissue
- **Liver:** Moderate expression, upregulated in response to injury

### 7.4 Mouse Models

| Model | Description | Phenotype | Reference |
|---|---|---|---|
| **Fgf1 knockout** | Global deletion | Impaired neurogenesis, metabolic abnormalities, increased susceptibility to doxorubicin-induced hepatotoxicity | |
| **F1A-CreERT2** | Cardiomyocyte-specific Fgf1 tracing | Enables lineage tracing of Fgf1-expressing cardiomyocytes | |
| **F1B-GFP** | 1B promoter-driven GFP | Enables isolation of neural stem/progenitor cells | |

---

## 8. Conclusion and Future Directions

FGF1 is a

## Related Clinical & Scientific Guides

* [PMCH Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/pmch-gene-structure-function-pathway)
* [CYLC1 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/cylc1-gene-structure-function-pathway)
* [CRX Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/developmental-biology/crx-gene-structure-function-pathway)