Changes in the Foxj1 expression of Schwann cells after sciatic nerve crush

Foxj1 is a member of the Forkhead box family of transcription factors expressed in multiple tissues during development and a major regulator of cilia development. It was reported that Foxj1 has a significant up-regulation after traumatic brain injury and plays an important role in central nervous system injury and repair. However, its expression and function in the peripheral nervous system lesion are not well understood. In this study, we investigated the spatiotemporal expression of Foxj1 in a rat sciatic nerve crush model. After never injury, we observed that Foxj1 had a significant up-regulation from 1 day, peaked at day 3 and then gradually decreased to the normal level at 4 weeks. At its peak expression, Foxj1 expressed mainly in Schwann cells (SCs) of the distal sciatic nerve segment from injury, but had few co-localizations in axons. Besides, the peak expression of Foxj1 was in parallel with proliferating cell nuclear antigen (PCNA), and numerous SCs expressing Foxj1 were PCNA positive. Collectively, we hypothesized that peripheral nerve crush-induced up-regulation of Foxj1 in the sciatic nerve was associated with Schwann cells proliferation.