EZH2 Regulates Neuronal Differentiation of Mesenchymal Stem Cells through PIP5K1C-dependent Calcium Signaling

Enhancer of zeste homolog 2 (EZH2) regulates stem cells renewal, maintenance, and differentiation into different cell lineages including neuron. Changes in intracellular Ca2+ concentration play a critical role in the differentiation of neurons. However, whether EZH2 modulates intracellular Ca2+ signaling in regulating neuronal differentiation from human mesenchymal stem cells (hMSCs) still remains unclear. When hMSCs were treated with a Ca2+ chelator or a PLC inhibitor to block IP3-mediated Ca2+ signaling, neuronal differentiation was disrupted. EZH2 bound to the promoter region of PIP5K1C to suppress its transcription in proliferating hMSCs. Interestingly, knockdown of EZH2 enhanced the expression of PIP5K1C, which in turn increased the amount of PI(4,5)P-2, a precursor of IP3, and resulted in increasing the intracellular Ca2+ level, suggesting that EZH2 negatively regulates intracellular Ca2+ through suppression of PIP5K1C. Knockdown of EZH2 also enhanced hMSCs differentiation into functional neuron both in vitro and in vivo. In contrast, knockdown of PIP5K1C significantly reduced PI(4,5)P-2 contents and intracellular Ca2+ release in EZH2-silenced cells and resulted in the disruption of neuronal differentiation from hMSCs. Here, we provide the first evidence to demonstrate that after induction to neuronal differentiation, decreased EZH2 activates the expression of PIP5K1C to evoke intracellular Ca2+ signaling, which leads hMSCs to differentiate into functional neuron lineage. Activation of intracellular Ca2+ signaling by repressing or knocking down EZH2 might be a potential strategy to promote neuronal differentiation from hMSCs for application to neurological dysfunction diseases.