FGF13 is not secreted from mouse neurons

Area of Science:

• Molecular and Cellular Biology
• Neuroscience

Background:

• Fibroblast growth factor 13 (FGF13) is a noncanonical FGF.
• FGF13 has been reported to regulate intracellularly voltage-gated sodium channels (VGSCs).
• Recent studies propose FGF13 is secreted and interacts with extracellular domains of neuronal VGSCs.

Purpose of the Study:

• To investigate the cellular localization and secretion of FGF13.
• To determine if FGF13 interacts with extracellular domains of VGSCs.

Main Methods:

• Transfection of FGF13 in a heterologous expression system.
• Analysis of endogenous FGF13 secretion from cultured neurons.
• Proximity labeling proteomics and other unbiased screens.

Main Results:

• Transfected and endogenous FGF13 were not detected in the extracellular space.
• FGF13 remains associated with cellular membranes.
• Evidence suggests FGF13 is not available for direct interaction with extracellular protein domains.

Conclusions:

• FGF13 is not secreted from cells.
• The proposed mechanism of FGF13 regulating neuronal VGSCs via extracellular interactions is not supported by this data.
• FGF13 likely functions intracellularly or within membranes.