Activation of extracellular-signal-regulated kinase-1/2 precedes and is required for injury-induced Schwann cell proliferation.

In English Activation of extracellular-signal-regulated kinase-1/2 (Erkl/2) by phosphorylation to p-Erkl/2, and proliferation of Schwann cells were investigated in the rat sciatic nerve by immunohistochemistry. Axotomy in vivo and culturing of nerve segments in vitro resulted in a rapid (30 min) increase of p-Erkl/2 in Schwann cells with peaks at 2 and 24 h. Proliferation measured by bromodeoxy uridine incorporation and immunostaining in vivo and in vitro 48 h after axotomy showed an increase in Schwann cell proliferation at the sites of Erkl/2 activation. The Erkl/2 inhibitor U0126 inhibited both the increase in p-Erkl/2 and the bromodeoxy uridine incorporation. We suggest that an increase in p-Erkl/2 is required for nerve injury-induced proliferation of Schwann cells.