Abstract
Amyotrophic lateral sclerosis (ALS) is a chronic neurodegenerative disease characterized by progressive degeneration of the motor neurons in the cortex, brainstem, and spinal cord. The etiology and mechanisms of selective motor neuron loss in ALS remain unknown. Wnt signaling is involved in neurodegenerative processes but little is known about the kinetic changes in Wnt signaling during ALS progression. In this study we used transcriptional microarray analysis to examine the expression of Wnt signaling components in the spinal cords of ALS transgenic SOD1(G93A) mice at different stages. We found that ALS onset led to the upregulation of Wnt signaling components and target genes involved in growth regulation and proliferation. We also determined the expression of Wnt inhibitory factor-1 (Wif1) and Wnt4 in the spinal cord of ALS transgenic mice at different stages by Western blot and immunofluorescence analysis. The protein levels of Wif1 and Wnt4 in the spinal cords of ALS transgenic mice were upregulated compared to those in wild-type mice. Moreover, the expression of Wif1 and Wnt4 in mature GFAP+ astrocytes was increased at the end stage of ALS. Our findings demonstrate that Wnt signaling is altered by spinal cord neuronal dysfunction in adult ALS transgenic mice, which provides new insight into ALS pathogenesis.