Neurotrophine-3 may contribute to neuronal differentiation of mesenchymal stem cells through the activation of the bone morphogenetic protein pathway.

We investigated whether neurotrophin-3 (NT-3) can promote differentiation of mouse bone mesenchymal stem cells (MSCs) into neurons via the bone morphogenetic protein pathway. MSCs were prepared from rat bone marrow and either transfected with pIRES2-EGFP or pIRES2-EGFP-NT-3 or treated with bone morphogenetic protein 4. The pIRES2-EGFP-NT-3-transfected MSCs further underwent noggin treatment or siRNA-mediated knockout of the TrkC gene or were left untreated. Immunofluorescence staining, real-time PCR and Western blot analyses were performed to evaluate the transcription and expression of neural-specific genes and BMP-Smad signaling. MSCs were efficiently transduced by the NT-3 gene via pIRES2-EGFP vectors. pIRES2- EGFP-NT-3 could initiate the transcription and expression of neural-specific genes, including nestin, NSE and MAP-2, and stimulate BMP-Smad signaling. The transcription and expression of neural-specific genes and BMP-Smad signaling were significantly suppressed by siRNA-mediated knockdown of the TrkC gene of MSCs. These findings suggest that the BMP signaling pathway may be a key regulatory point in NT-3-transfected neuronal differentiation of MSCs. The BMP and neurotrophin pathways contribute to a tightly regulated signaling network that directs the precise connections between neuronal differentiation of MSCs and their targets.