Abstract: Objective    To explore the role and mechanism of Semaphorin3B (SEMA3B) in Schwann cells during Wallerian degeneration in the injured peripheral nerve.    Methods    The Schwann cell specific SEMA3B knockout (cKO) mice and the littermate Cre mice were selected as an experimental group and a control group, respectively. The in vivo and in vitro models of Wallerian degeneration by nerve transection injury and nerve explant culture were prepared. Five days later, the tissues were collected to perform immunofluorescence and Western blotting with antibodies of MBP, NF, c-Jun, MAG, p-AKT, AKT, p- GSK3β, GSK3β, p-ERK, ERK, p-JNK, and JNK. Moreover, SC79 (the agonist of AKT) was used to perform the rescue experiment in the in vitro model.    Results    After 5 days of nerve injury, the expression of MBP and NF in both in vivo and in vitro models of the cKO group was higher than that of the Cre group, indicating Wallerian degeneration was delayed in the cKO group. Compared with the Cre group, the expression of c-Jun was lower and MAG was higher in the cKO group, suggesting that the Schwann cell dedifferentiation was reduced. The expression of p-AKT and p- GSK3β was down-regulated, while there was no significant difference in the levels of p-ERK and p-JNK. The administration of AKT agonist (SC79) could reverse the changes of MBP, and NF caused by SEMA3B cKO.    Conclusions    SEMA3B conditional knockdown in Schwann cells delay the Wallerian degeneration through inhibiting the AKT/ GSK3β pathway.

Key words:  Schwann cell； ,  , Wallerian degeneration； ,  , Peripheral nerve injury； ,  , SEMA3B