c-Fos is necessary for HGF-mediated gene regulation and cell migration in Schwann cells

We previously reported that the expression of hepatocyte growth factor (HGF) was highly induced after peripheral nerve damage, and that c-Fos is one of many cellular genes whose expressions are affected by the increased level of HGF[1]. c-Fos is an important component of AP-1 heterodimer, but its role has not been clearly understood in the context of HGF and Schwann cells (SCs). In this study, we investigated the relationship between HGF and c-Fos. First, it was confirmed that the c-Fos was increased in SCs after nerve injury, while this effect abrogated by PHA-665752, an inhibitor of c-met receptor. When primary SCs were treated with recombinant HGF protein, c-Fos expression was regulated in a typical quick, transient fashion at both RNA and proteins levels. HGF-mediated induction of c-Fos expression was highly suppressed by specific inhibitors of ERK and CREB, respectively. The knock down of c-Fos expression by siRNA almost completely blocked various HGF-mediated effects in SCs, such as induction of gene expression of GDNF, LIF, and c-Myc, and migration of SCs, indicating that c-Fos might play a key role in HGF effects. Taken together, our results suggested that c-Fos plays a key role(s) in HGF-mediated effects on neurotrophic genes and cell migration.