Activation of the Wnt/β-catenin signaling cascade after traumatic nerve injury

S Kurimoto, J Jung, M Tapadia, J Lengfeld, D Agalliu… - Neuroscience, 2015 - Elsevier
S Kurimoto, J Jung, M Tapadia, J Lengfeld, D Agalliu, M Waterman, T Mozaffar, R Gupta
Neuroscience, 2015Elsevier
Recent data have shown that preservation of the neuromuscular junction (NMJ) after
traumatic nerve injury helps to improve functional recovery with surgical repair via matrix
metalloproteinase-3 (MMP3) blockade. As such, we sought to explore additional pathways
that may augment this response. Wnt3a has been shown to inhibit acetylcholine receptor
(AChR) clustering via β-catenin-dependent signaling in the development of the NMJ.
Therefore, we hypothesized that Wnt3a and β-catenin are associated with NMJ …
Abstract
Recent data have shown that preservation of the neuromuscular junction (NMJ) after traumatic nerve injury helps to improve functional recovery with surgical repair via matrix metalloproteinase-3 (MMP3) blockade. As such, we sought to explore additional pathways that may augment this response. Wnt3a has been shown to inhibit acetylcholine receptor (AChR) clustering via β-catenin-dependent signaling in the development of the NMJ. Therefore, we hypothesized that Wnt3a and β-catenin are associated with NMJ destabilization following traumatic denervation. A critical size nerve defect was created by excising a 10-mm segment of the sciatic nerve in mice. Denervated muscles were then harvested at multiple time points for immunofluorescence staining, quantitative real-time PCR, and western blot analysis for Wnt3a and β-catenin levels. Moreover, a novel Wnt/β-catenin transgenic reporter mouse line was utilized to support our hypothesis of Wnt activation after traumatic nerve injury. The expression of Wnt3a mRNA was significantly increased by 2 weeks post-injury and remained upregulated for 2 months. Additionally, β-catenin was activated at 2 months post-injury relative to controls. Correspondingly, immunohistochemical analysis of denervated transgenic mouse line TCF/Lef:H2B-GFP muscles demonstrated that the number of GFP-positive cells was increased at the motor endplate band. These collective data support that post-synaptic AChRs destabilize after denervation by a process that involves the Wnt/β-catenin pathway. As such, this pathway serves as a potential therapeutic target to prevent the motor endplate degeneration that occurs following traumatic nerve injury.
Elsevier