Bone marrow-derived mesenchymal stem cells up-regulate acetylcholine receptor delta subunit through NRG/ErbB3-mediated mitogen-activated protein kinase pathway.

To investigate the effect of bone marrow-derived mesenchymal stem cells (BMSCs) on the expression of acetylcholine receptor delta subunit (AChRd), the murine skeletal muscle cell line Sol8 were grown in DMEM with 20% fetal bovine serum added with (conditional medium group) or without (control group) conditional medium of BMSC cells for 48 hours. RT-PCR and Western blot were performed to access the mRNA and protein levels of AChRd in Sol8 cells, respectively. Western blot was used to detect total and phosphorylated protein levels of Ras, Raf-1, Mek1/2, and Erk1/2, respectively. NRG-1 antibody added in conditional medium of BMSCs, si-ErbB3, and four Ras/Raf/MEK/ERK pathway inhibitors (FTS, Sulindac, U0126, and PD98059) were using to investigate the effect of AChRd levels. Our studies indicated that expression of AChRd was significantly enhanced in the conditional medium group when compared with those in control group and phosphorylation of Ras, Raf, Erk1/2 in Sol8 cells was also increased. Although gene silencing for ErbB3 gene, adding of NRG-1 antibody in conditional medium of BMSCs or treatment of Ras/Raf/MEK/ERK pathway inhibitors can down-regulate expression of AChRd and phosphorylation, which suggesting that the Ras/Raf/MEK/ERK pathway may be involved in BMSCs-induced expression of AChRd.