Cobalt chloride induces neuronal differentiation of human mesenchymal stem cells through upregulation of microRNA-124a.

Abstract Human mesenchymal stem cells (hMSCs) are known to have the capacity to differentiate into various cell types, including neurons. To examine our hypothesis that miRNA was involved in neuronal differentiation of hMSCs, CoCl 2 , a hypoxia-mimicking agent was used to induce neuronal differentiation, which was assessed by determining the expression of neuronal markers such as nestin and Tuj1. Treatment of hMSCs with CoCl 2 led to increased expression of miR-124a, a neuron-specific miRNA. HIF-1α silencing and JNK inhibition abolished CoCl 2 -induced miR-124a expression, suggesting that JNK and HIF-1α signals were required for the miR-124a expression induced by CoCl 2 in hMSCs. Overexpression of miR-124a or CoCl 2 treatment suppressed the expression of anti-neural proteins such as SCP1 and SOX9. Silencing of both SCP1 and SOX9 induced neuronal differentiation of hMSCs, indicating that suppression of miR-124a targets is important for CoCl 2 -induced neuronal differentiation of hMSCs. Knockdown of HIF-1α or inhibition of JNK restored the expression of SCP1 and SOX9 in CoCl 2 -treated cells. Inhibition of miR-124a blocked CoCl 2 -induced suppression of SCP1 and SOX9 and abolished CoCl 2 -induced neuronal differentiation of hMSCs. Taken together, we demonstrate that miR-124a is critically regulates CoCl 2 -induced neuronal differentiation of hMSCs by suppressing the expression of SCP1 and SOX9.