Sensory neuron–expressed FGF13 controls nociceptive signaling in diabetic neuropathy models
Aditya K. Singh, et al.
Aditya K. Singh, et al.
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Research Article Neuroscience Public Health

Sensory neuron–expressed FGF13 controls nociceptive signaling in diabetic neuropathy models

Abstract

Nociception involves complex signaling, yet intrinsic mechanisms bidirectionally regulating this process remain unexplored. Here, we show that the fibroblast growth factor 13 (FGF13)/Nav1.7 protein–protein interaction (PPI) complex bidirectionally modulates nociception, and that the FGF13/Nav1.7 ratio is upregulated in type 2 diabetic neuropathy (T2DN). PW164, an FGF13/Nav1.7 channel C-terminal tail domain (CTD) PPI interface inhibitor, which reduces complex assembly, selectively suppressed Na+ currents sensitized by capsaicin-induced activation of TRPV1 channels in human induced pluripotent stem cell–derived (hIPSC-derived) sensory neurons and inhibited mechanical and thermal hyperalgesia in mice. FGF13 silencing mimics PW164 activity in culture and in vivo. Conversely, ZL192, an FGF13 ligand that stabilizes FGF13/Nav1.7 CTD assembly, sensitized Na+ currents in hIPSC-derived sensory neurons and exerted pronociceptive behavioral responses in mice. ZL192’s effects were abrogated by FGF13 silencing in culture and in vivo and recapitulated by FGF13 overexpression. In a model of T2DN, PW164 injection reduced mechanical hyperalgesia locally and contralaterally without systemic side effects. In donor-derived dorsal root ganglia neurons, FGF13 and Nav1.7 proteins colocalized, and the FGF13/Nav1.7 protein ratio was upregulated in patients with T2DN. Lastly, we found that SCN9A variant V1831F, associated with painless diabetic neuropathy, abolished PW164-directed modulation of the FGF13/Nav1.7 PPI interface. Thus, FGF13 is a rheostat of nociception and promising therapeutic target for diabetic neuropathy pain.

Authors

Aditya K. Singh, Matteo Bernabucci, Nolan M. Dvorak, Zahra Haghighijoo, Jessica Di Re, Nana A. Goode, Feni K. Kadakia, Laura A. Maile, Olumarotimi O. Folorunso, Paul A. Wadsworth, Cynthia M. Tapia, Pingyuan Wang, Jigong Wang, Haiying Chen, Yu Xue, Jully Singh, Kali Hankerd, Isaac J. Gamez, Makenna Kager, Vincent Truong, Patrick Walsh, Stephanie I. Shiers, Nishka Kuttanna, Hanyue Liao, Margherita Marchi, Erika Salvi, Ilaria D’Amato, Daniela D’Amico, Parsa Arman, Catharina G. Faber, Rayaz A. Malik, Marina de Tommaso, Dan Ziegler, Krishna Rajarathnam, Thomas A. Green, Peter M. Grace, Matthew R. Sapio, Michael J. Iadarola, Gregory D. Cuny, Diana S. Chow, Giuseppe Lauria Pinter, Steve Davidson, Dustin P. Green, Jun-Ho La, Jin Mo Chung, Jia Zhou, Theodore J. Price, Elizabeth Salisbury, Subo Yuan, Fernanda Laezza

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Figure 8

Changes in FGF13/Nav1.7 complex formation correlate with diabetic neuropathy.

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Changes in FGF13/Nav1.7 complex formation correlate with diabetic neurop...
(A) Expression profile of FGF13 and SCN9A in molecularly defined neuronal subtypes, obtained from previous investigations of spatial transcriptomics in human dorsal root ganglia (47). (B) RNAscope-based expression pattern of FGF13 (red) and SCN9A (green) in donor-derived DRG neurons. The nuclear marker 4′,6-diamidino-2-phenylindole (DAPI) is shown in blue in the 3 panels on the left. A pie chart summarizes the percentage of neurons expressing each individual probe or pairs of probes. Quantification was done from 3 donors. Scale bars: 500 um (left); 50um (right top and bottom). (C) Representative confocal images from human nondiabetic (NDC) controls and patients with type-2 diabetic neuropathy (T2DN) DRG neurons stained with anti-FGF13 antibody (red), anti-Nav1.7 antibody (green), and peripherin (blue). To the right, summary bar graphs of mean and ratio fluorescence intensity for NDC versus T2DN. 21. White arrowheads indicate representative cells exhibiting FGF13/Nav1.7 colocalization. Scale bar: 50 μm. (D) Schematic illustration of SCN9A rare variants in the coding region of the Nav1.7 CTD found associated with neuropathies (top). ackFold model of the Nav1.7/FGF13 complex; the interaction with FGF13 occurs intracellularly. Close up showing the V1831F residue in direct interaction with the R110 residue on FGF13. R110 is a structural determinant of the FGF13/Nav1.7 CTD PPI interface. DDmut predicts the V1831F mutation to destabilize the FGF13/Nav1.7 complex ΔΔGStability = –1.75 kcal/mol. On the bottom right, LCA analysis of FGF13/Nav1.7 vs FGF13/Nav1.7 V1831F mutation does not alter complex assembly but prevents PW164’s pharmacological activity. Data are mean ± SEM, ns = not significant, *P < 0.05; **P < 0.01; ***P < 0.001, 1-way ANOVA post-hoc Tukey HSD (D); Mann Whitney test (C).