| Attribute |
Value |
References |
| Symbol |
FGF19 |
|
| Name |
Fibroblast Growth Factor 19 |
|
| Chromosome |
11q13.1 |
|
| NCBI Gene ID |
2259 |
|
| UniProt ID |
Q9KUM4 |
|
| Ensembl ID |
ENSG00000162337 |
|
FGF19 (Fibroblast Growth Factor 19) is a member of the endocrine subfamily of fibroblast growth factors (FGFs) that functions as a metabolic regulator. Unlike classic FGFs that act locally, FGF19 functions in an endocrine manner, traveling from its site of production (small intestine) to regulate metabolic processes in the liver and other tissues. It signals through the FGF receptor FGFR4, with Klothos (KL) as the required co-receptor.
FGF19 is one of the "metabolic FGFs" (along with FGF21 and FGF23) that act as endocrine factors, regulating systemic metabolism. Unlike the canonical FGFs (FGF1-FGF10), these metabolic FGFs have low heparin-binding affinity, allowing them to enter circulation.
The endocrine FGF signaling pathway:
- Production: FGF19 is expressed in the small intestine (ileum), particularly in enterocytes
- Secretion: Secreted into portal circulation
- Receptor binding: Binds to FGFR4 (FGF Receptor 4) on target cells
- Co-receptor requirement: Requires Klotho (KL) for signaling
- Metabolic effects: Regulates bile acid synthesis, glucose metabolism, and energy expenditure
FGF19 binds specifically to FGFR4, a receptor tyrosine kinase expressed predominantly in the liver. The signaling cascade involves:
- FGF19 → FGFR4 → FRS2 → RAS/MAPK pathway
- Activation of downstream pathways including PI3K/AKT and MAPK/ERK
- Regulation of gene expression in hepatocytes
FGFR4 is the only FGFR that can respond to FGF19, providing tissue-specific signaling. This specificity makes the FGF19-FGFR4 axis an attractive therapeutic target.
FGF19 regulates several metabolic processes:
-
Bile Acid Homeostasis
- Suppresses cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme in bile acid synthesis
- Reduces hepatic bile acid production
- Feedback regulation of bile acid levels
-
Glucose Metabolism
- Improves insulin sensitivity
- Reduces hepatic glucose production
- Promotes glucose uptake in peripheral tissues
-
Energy Expenditure
- Increases metabolic rate
- Promotes weight loss in obesity models
- Increases fatty acid oxidation
-
Lipid Metabolism
- Reduces hepatic triglyceride accumulation
- Improves lipid profiles
FGF19 is primarily associated with metabolic diseases:
-
Obesity and Type 2 Diabetes
- FGF19 signaling is dysregulated in obesity
- Therapeutic potential for metabolic syndrome
- Recombinant FGF19 analogs are in development
-
Non-Alcoholic Fatty Liver Disease (NAFLD)
- FGF19 modulates hepatic lipid accumulation
- May protect against steatosis
-
Dyslipidemia
- Effects on cholesterol and triglyceride metabolism
¶ FGF19 in Neurodegeneration: Current Understanding
Direct evidence for FGF19 involvement in neurodegeneration is limited. However, several relevant connections exist:
-
Metabolic Syndrome and Neurodegeneration
- Type 2 diabetes is a risk factor for AD and PD
- FGF19 improves insulin sensitivity, potentially benefiting brain health
-
Bile Acids and Brain Function
- Bile acids can cross the blood-brain barrier
- Farnesoid X receptor (FXR) signaling in the brain is emerging
- FGF19 regulates bile acid production, indirectly affecting brain chemistry
-
FGF Signaling in the Brain
- Other FGFs (FGF2, FGF21) have neuroprotective effects
- While FGF19 doesn't signal in the brain directly, systemic metabolic effects could influence neurodegeneration
FGF19 affects:
- Cardiac function (may have protective effects)
- Vascular smooth muscle cell proliferation
- Atherosclerosis progression
FGF19 expression is highly restricted:
- Small intestine (ileum) — primary site
- Liver — minimal expression
- Colon — low expression
Unlike other FGFs, FGF19 is not significantly expressed in the brain or nervous system. The original page's description of brain expression appears to be incorrect and may reflect confusion with other growth factors.
FGF19 expression is regulated by:
- Bile acids: Activate FXR in enterocytes, inducing FGF19 expression
- Cholesterol: Dietary cholesterol affects expression
- Enterohepatic circulation: Bile acid flux regulates transcription
flowchart TD
A["FGF19 Gene<br/>11q13.1"] --> B["FGF19 Protein"]
B --> C["Portal Circulation"]
C --> D["Liver<br/>Hepatocytes"]
D --> E["FGFR4 Receptor<br/>+ Klotho Co-receptor"]
E --> F["Signal Transduction"]
F --> G["RAS/MAPK Pathway"]
F --> H["PI3K/AKT Pathway"]
G --> I["Gene Expression<br/>Regulation"]
H --> I
I --> J["Bile Acid<br/>Synthesis ↓"]
I --> K["Glucose<br/>Metabolism ↑"]
I --> L["Energy<br/>Expenditure ↑"]
J --> M["Metabolic<br/>Homeostasis"]
K --> M
L --> M
M --> N["Systemic Effects"]
N --> O["Brain Function<br/>(Indirect)"]
| Factor |
Primary Site |
Primary Receptor |
Main Functions |
| FGF19 |
Small intestine |
FGFR4 |
Bile acid, glucose, energy |
| FGF21 |
Liver, adipose |
FGFR1/2 + β-Klotho |
Insulin sensitivity, lipid metabolism |
| FGF23 |
Bone |
FGFR1/2 + Klotho |
Phosphate, vitamin D metabolism |
Recombinant FGF19 analogs are being developed for:
- Obesity: Promote weight loss
- Type 2 Diabetes: Improve insulin sensitivity
- NAFLD/NASH: Reduce hepatic steatosis
- FGF19's role in tumors (potential oncogenic effects)
- Species-specific activity differences
- Safety concerns requiring careful monitoring
Targeting FGF19 for metabolic disease could indirectly benefit brain health by:
- Improving systemic insulin sensitivity
- Reducing neuroinflammation from metabolic dysfunction
- Modulating bile acid signaling
-
FGF19-FGFR4 axis: The specific interaction between FGF19 and FGFR4 provides tissue-selective targeting.
-
Bile acid regulation: FGF19 is the primary endocrine regulator of bile acid synthesis.
-
Metabolic effects: FGF19 improves glucose homeostasis and promotes energy expenditure.
-
Therapeutic potential: FGF19 analogs represent novel treatments for metabolic disease.