Identification of Fibroblast Growth Factor Receptor 3 (FGFR3) as a Protein Receptor for Botulinum Neurotoxin Serotype A (BoNT/A)
Figure 5
FGFR3 and SV2C are both expressed on motor nerve terminals in rat skeletal muscle.
(A) Photomicrographs from normal rat TA muscle cross-sections (A–H) and from muscles pre-treated with 10 U of BOTOX (I–P). Sections show immunostaining for SV2C (red, A, I), FGFR3 (red, E, M), SNAP25 (green, B, F) and SNAP25197 (green, J, N). Nicotinic acetylcholine receptors (nAChR) are labeled by α-bungarotoxin Alexa-Fluor 647 (blue, C, G, K, O). The last column shows a merge of the staining patterns within that row on a muscle fiber background imaged by DIC optics (M+DIC). BV, Blood Vessel; MB, Myoblast; MF, myofiber; NMJ, neuromuscular junction. Note the overlap in IR signal for FGFR3 and SV2C with SNAP25197 and directly adjacent to the pattern of post-synaptic nAChR expression. Scale bar = 10 µm in H (A–H) and P (I–P). (B) A. Photomicrograph from a saline-treated rat TA muscle cross-section showing immune-staining for FGFR3 (red) co-localized with α-bungarotoxin-labeled nAChRs (blue). No staining was observed for SNAP25197 (green) in these sections. B. A normal rat muscle cross-section immune-stained with peptide-quenched FGFR3 antibodies and lacking the SNAP25 primary antibody shows only α-Bgt-labeled nAChRs. Scale bar = 10 µm. BV, Blood Vessel; MF, myofiber; NMJ, neuromuscular junction.