NUAK2 mediated regulation of Schwann Cell proliferation and migration in peripheral nerve injury via YAP.

ABSTRACT

NUAK2 is a member of the AMP-activated protein kinase (AMPK) family, which plays an essential role in cellular processes such as apoptosis, proliferation, and cell fate. Recent studies have already shown that silencing of NUAK2 blocks proliferation and promotes apoptosis of human melanoma cells and liver cancer cells. In addition, NUAK2 is involved in the development of glioblastoma via regulating the expression of cancer stem cell-related genes, and it promotes the cell cycle entry in the glioblastoma cells. However, the expression and the role of NUAK2 in the progress of peripheral nerve regeneration after injury are yet to be elucidated. We observed that NUAK2 was upregulated following distal sciatic nerve crush (SNC). Interestingly, we discovered that NUAK2 showed co-localization with S100 (Schwann cell marker). Furthermore, we found that the NUAK2 had a spatiotemporal protein expression, which was consistent with proliferating cell nuclear-antigen (PCNA). The protein level of NUAK2 and YAP was upregulated in the model of TNF-α-induced Schwann cell (SC) proliferation. Furthermore, flow cytometry analysis, CCK-8, transwell assays, and wound healing assays were all performed with the purpose of exploring the role of NUAK2 in the regulation of SC proliferation and migration. More importantly, we found that NUAK2-deficient SCs showed significantly reduced expression of Yes-associated protein (YAP). Bioinformatic analysis identified upstream regulators of NUAK2 and NUAK2-associated genes (e.g., YAP1). Finally, we investigated the recovery changes during regeneration progress through the walking track analysis. Thus, we speculated that NUAK2 was involved in biochemical and physiological responses of SCs after SNC via YAP-driven proliferation and migration, and this study determined the importance of NUAK2 as a potential target in peripheral nerve regeneration.