The Regenerating Spinal Cord of Gecko Maintains Unaltered Expression of β-Catenin Following Tail Amputation

The Wingless/Integrated (Wnt) signaling pathway plays important roles in central nervous system (CNS) development and regeneration, and beta-catenin, the central component, has been considered in association with adult neurogenesis. To decipher its roles on spontaneous spinal cord regeneration, we cloned beta-catenin from Gekko japonicus and examined its function in regenerating spinal cord. The protein was localized in the neurons and oligodendrocytes and maintained a stable expression levels during the spinal cord regeneration. The temporal pattern of expression has been found to be completely distinct with those of glycogen synthase kinase 3 beta (GSK3 beta). Experiments of gain-of-function by overexpression of full length beta-catenin or stabilized Delta N90-beta-catenin revealed that the accumulated protein attenuates the elongation of neurites and oligodendrocyte process. Knockdown of endogenous beta-catenin, however, decreased proliferation of oligodendrocytes by affecting expression of downstream lef1 and c-jun. The upregulated extracellular matrix fibronectin in injured cord was found to be inefficient in regulation of beta-catenin expression. Our results suggest that a tightly regulated stable expression of beta-catenin is required for the spontaneous spinal cord regeneration.