Conclusions
This study demonstrates that Wnt5a protects MNs in ALS by regulating cell viability, proliferation, apoptosis, and neurite growth through the Wnt/Ca2+ signaling pathway. Our data indicate that the non-canonical Wnt/Ca2+ signaling pathway regulated by Wnt5a is involved in MN degeneration in ALS.
Methods
The expressions of CaMKII-α, CaMKII-β and TAK1 in the spinal cord of SOD1G93A ALS transgenic mice at different ages were determined using western blotting and immunofluorescence. The level of Ca2+ and cell apoptosis were assessed with flow cytometry and cell viability was evaluated using MTS assay. Cell proliferation was analyzed by the EdU cell proliferation assay. Neurite length was measured after treatment with retinoic acid.
Results
CaMKII-α, CaMKII-β, and TAK1 were down-regulated in the spinal cord of ALS mice. Ca2+ level and CaMKII-α, CaMKII-β, and TAK1 were down-regulated in SOD1G93A mutant NSC-34 cells. Expression of Ca2+, CaMKII-α, CaMKII-β, and TAK1 were up-regulated in SOD1G93A mutant NSC-34 cells after Wnt5a overexpression and down-regulated after Wnt5a knockdown. Overexpression of Wnt5a promoted cell viability and proliferation but inhibited cell apoptosis. Contrastingly, Wnt5a knockdown inhibited cell viability and proliferation but promoted cell apoptosis. CaMKII inhibitor KN-93 and CaMKII activator oleic acid reversed changes in cell viability, proliferation, apoptosis, and neurite outgrowth induced by Wnt5a overexpression and knockdown. Conclusions: This study demonstrates that Wnt5a protects MNs in ALS by regulating cell viability, proliferation, apoptosis, and neurite growth through the Wnt/Ca2+ signaling pathway. Our data indicate that the non-canonical Wnt/Ca2+ signaling pathway regulated by Wnt5a is involved in MN degeneration in ALS.