What Is FGF13? Definition and What Research Reports

FGF13 (fibroblast growth factor 13, also called FHF2) is a protein encoded by the X-linked FGF13 gene and belongs to the fibroblast growth factor homologous factor (FHF) subfamily. Despite the name, FGF13 is generally described as an intracellular protein: it lacks a conventional secretion signal and, in contrast to the classical secreted FGFs, is not considered a receptor-activating growth factor in the usual sense. Instead, the literature characterises it as a scaffolding and regulatory protein that interacts with voltage-gated ion channels, microtubules, membrane lipids and nuclear proteins, with multiple splice isoforms (for example FGF13A, FGF13B/VY and others) that differ at the N-terminus and can localise differently within the cell.

This page is for educational purposes only and is not medical advice; consult a licensed physician for any health question. FGF13 is discussed here strictly as a molecular biology term that appears in published research.

What class of molecule is FGF13?

FGF13 sits in the FHF branch of the fibroblast growth factor superfamily, alongside FGF11, FGF12 and FGF14. Structurally these proteins share the β-trefoil core fold of FGFs, which is why they carry FGF names, but functionally they are usually grouped separately because they operate inside the cell. FGF13 is expressed widely, with the literature describing expression in cardiomyocytes, sensory neurons of the dorsal root ganglia, central neurons, and various other tissues.

Key features described in the literature

• Family: fibroblast growth factor homologous factor (FHF) subfamily, also designated FHF2.
• Location: intracellular — cytoplasm, submembrane compartments and, for some isoforms, the nucleus.
• Reported binding partners: voltage-gated sodium channel C-termini, microtubule-associated machinery, and nucleolar proteins depending on isoform.
• Gene: X-chromosomal; isoform diversity arises from alternative first exons and splicing.

How the term is used in peptide and protein research

In research writing, "FGF13" almost always refers to the endogenous protein or its gene, not to an administered compound. Papers typically use genetic tools — knockout, conditional deletion, knockdown or overexpression — to ask what happens when FGF13 levels change in a particular tissue. That is an important distinction for readers who encounter FGF13 in lists of "peptides": unlike secreted signalling peptides that can be applied to cells or animals from the outside, FGF13 is studied as an intracellular protein whose levels are manipulated genetically. The verified literature summarised below reflects that pattern.

What the published literature reports

Cardiac electrophysiology and ion channels

A 2025 study in Circulation Research reported that FGF13 regulated cardiomyocyte impulse propagation through connexin-43 (Cx43) trafficking in a manner independent of voltage-gated sodium channels, indicating a role for FGF13 beyond its classical channel-binding function (PMID 41200819). Separately, researchers reported in The Journal of Clinical Investigation that FGF13, described as an auxiliary subunit of the cardiac sodium channel Na_V1.5, modulated channel behaviour by regulating membrane cholesterol rather than by binding the channel directly (PMID 40794434). Together these two reports describe mechanisms in which FGF13 influences cardiac excitability indirectly, through trafficking and membrane lipid composition.

Cardiac ageing has also been examined. A 2025 report in Advanced Science described an FGF13–caveolin-1 axis and reported that this axis contributed to premature cardiac ageing in doxorubicin- and D-galactose-induced models (PMID 40184605).

Sensory neurons and pain models

FGF13 appears repeatedly in the nociception literature. Researchers reported in The Journal of Clinical Investigation that FGF13 expressed in sensory neurons controlled nociceptive signalling in diabetic neuropathy models (PMID 40662354). In a chemotherapy-related model, the study reported that FGF13 deficiency ameliorated paclitaxel-induced neuropathic pain, with the described mechanism involving inhibition of VASH1-mediated microtubule detyrosination and promotion of mitophagy (PMID 42312425). These are preclinical animal and cellular findings about an endogenous protein; they are not statements about any administered product.

Central nervous system

In a mouse model of Parkinson's disease, researchers reported that neuronal FGF13 inhibited mitochondria-derived damage signals and thereby limited neuroinflammation and neurodegeneration (PMID 40344619). Notably, the direction of effect in that central nervous system model — where FGF13 was described as protective — differs from the peripheral pain models above, where loss of FGF13 was reported to reduce pain behaviour (PMID 42312425). This kind of tissue- and context-dependence is a recurring theme in the FGF13 literature.

Metabolism

A 2025 paper in Cell Metabolism reported that ceramide-induced FGF13 impaired systemic metabolic health, linking a lipid signal to FGF13 expression and downstream metabolic consequences (PMID 40169001).

Cancer cell biology

Isoform-specific work has also been published. A 2023 report in Biochemical and Biophysical Research Communications described that the FGF13A isoform interacted with the nucleolar proteins NPM1 and UBF and inhibited the invasion of bladder cancer cells (PMID 37603967). That finding illustrates the nuclear/nucleolar side of FGF13 biology, distinct from its membrane-associated roles.

Reported contexts at a glance

Safety and Adverse Events: What Studies Report

The verified FGF13 literature summarised on this page consists of mechanistic laboratory and animal studies of an endogenous intracellular protein, not clinical trials of an administered substance, so it does not contain human safety, tolerability or adverse-event data. The nearest thing to a harm-related observation is that researchers reported ceramide-induced FGF13 impaired systemic metabolic health in their model (PMID 40169001) and that the FGF13–caveolin-1 axis was implicated in premature cardiac ageing in doxorubicin- and D-galactose-induced models (PMID 40184605) — findings about the protein's biology, not about any product. No dosing information exists in these papers because no FGF13 preparation was administered as a therapeutic in them.

Limitations of the current evidence

• Preclinical scope. The cited work used cells and rodent models; findings in animals do not automatically translate to humans.
• Direction depends on tissue. Loss of FGF13 was reported to reduce neuropathic pain behaviour in one model (PMID 42312425) while neuronal FGF13 was reported to be protective in a Parkinson's model (PMID 40344619).
• Isoform complexity. Isoform-specific behaviour, such as the nucleolar interactions reported for FGF13A (PMID 37603967), means results are not always interchangeable between studies.
• No human therapeutic data. The verified papers do not report approved uses, human dosing or clinical outcomes.

References

• Ceramide-induced FGF13 impairs systemic metabolic health (Cell Metabolism, 2025)
• FGF13 Regulates VGSC-Independent Cardiomyocyte Impulse Propagation via Cx43 Trafficking (Circulation Research, 2025)
• Neuronal FGF13 Inhibits Mitochondria-Derived Damage Signals to Prevent Neuroinflammation and Neurodegeneration in a Mouse Model of Parkinson's Disease (Advanced Science, 2025)
• The NaV1.5 auxiliary subunit FGF13 modulates channels by regulating membrane cholesterol independent of channel binding (The Journal of Clinical Investigation, 2025)
• FGF13A interacts with NPM1 and UBF and inhibits the invasion of bladder cancer cells (Biochemical and Biophysical Research Communications, 2023)
• The FGF13-Caveolin-1 Axis: A Key Player in the Pathogenesis of Doxorubicin- and D-Galactose-Induced Premature Cardiac Aging (Advanced Science, 2025)
• Sensory neuron-expressed FGF13 controls nociceptive signaling in diabetic neuropathy models (The Journal of Clinical Investigation, 2025)
• FGF13 Deficiency Ameliorates Paclitaxel-Induced Neuropathic Pain by Inhibiting VASH1-Mediated Microtubule Detyrosination to Promote Mitophagy (Advanced Science, 2026)