Fibroblast growth factor 9 stimulates neurite outgrowth through NF-kB signaling in striatal cell Huntington’s disease models

Proper development of neuronal cells is important for brain functions, and impairment of neuronal development may lead to neuronal disorders, implying that improvement in neuronal development may be a therapeutic direction for these diseases. Huntington’s disease (HD) is a neurodegenerative disease characterized by impairment of neuronal structures, ultimately leading to neuronal death and dysfunctions of the central nervous system. Based on previous studies, fibroblast growth factor 9 (FGF9) may provide neuroprotective functions in HD, and FGFs may enhance neuronal development and neurite outgrowth. However, whether FGF9 can provide neuronal protective functions through improvement of neuronal morphology in HD is still unclear. Here, we study the effects of FGF9 on neuronal morphology in HD and attempt to understand the related working mechanisms. Taking advantage of striatal cell lines from HD knock-in mice, we found that FGF9 increases neurite outgrowth and upregulates several structural and synaptic proteins under HD conditions. In addition, activation of nuclear factor kappa B (NF-kB) signaling by FGF9 was observed to be significant in HD cells, and blockage of NF-kB leads to suppression of these structural and synaptic proteins induced by FGF9, suggesting the involvement of NF-kB signaling in these effects of FGF9. Taken these results together, FGF9 may enhance neurite outgrowth through upregulation of NF-kB signaling, and this mechanism could serve as an important mechanism for neuroprotective functions of FGF9 in HD. ### Competing Interest Statement The authors have declared no competing interest. * (HD) : Huntington’s disease (FGF9) : Fibroblast growth factor 9 (NF-kB) : Nuclear factor kappa B (PD)\ : Parkinson’s disease (Q7) : STHdhQ7/Q7 (Q111) : STHdhQ111/Q111 (MAP2) : Microtubule associated protein (GAP-43) : Growth association protein 43 (FGFR) : FGF receptor (Shh) : Sonic Hedge Hog