Dabrafenib Promotes Schwann Cell Differentiation by Inhibition of the MEK-ERK Pathway

Schwann cell differentiation involves a dynamic interaction of signaling cascades. However, much remains to be elucidated regarding the function of signaling molecules that differ depending on the context in which the molecules are engaged. Here, we identified a small molecule, dabrafenib, which promotes Schwann cell differentiation in vitro and exploited this compound as a pharmacological tool to understand the molecular mechanisms regulating Schwann cell differentiation. The results indicated that dabrafenib inhibited ERK phosphorylation and enhanced ErbB2 autophosphorylation and Akt phosphorylation, and the effects of dabrafenib on ErbB2 and Akt phosphorylation were phenocopied by pharmacological inhibition of the MEK-ERK signaling pathway. However, the small molecule inhibitors of MEK and ERK had no effect on the expression of Oct6 and EGR2, which are key transcription factors that drive Schwann cell differentiation. In addition, pharmacological inhibition of phosphatidylinositol-3-kinase (PI3K) almost completely interfered with dabrafenib-induced Schwann cell differentiation. These results suggest that the ErbB2-PI3K-Akt axis is required for the induction of Schwann cell differentiation by dabrafenib in vitro. Although additional molecules targeted by dabrafenib remain to be identified, our data provides insights into the crosstalk that exists between the MEK-ERK signaling pathway and the PI3K-Akt axis in Schwann cell differentiation.

Automated summary

The small molecule dabrafenib has been identified to promote Schwann cell differentiation by inhibiting ERK phosphorylation and enhancing ErbB2 and Akt phosphorylation. However, MEK and ERK inhibitors have no effect on key transcription factor expression, while pharmacological inhibition of PI3K interferes with dabrafenib-induced differentiation. This suggests that the ErbB2-PI3K-Akt axis is essential for Schwann cell differentiation induced by dabrafenib in vitro.