Role of Prion protein-EGFR multimolecular complex during neuronal differentiation of human dental pulp-derived stem cells.

Cellular prion protein (PrPC) is expressed in a wide variety of stem cells in which regulates their self-renewal as well as differentiation potential. In this study we investigated the presence of PrPC in human dental pulp-derived stem cells (hDPSCs) and its role in neuronal differentiation process. We show that hDPSCs expresses early PrPC at low concentration and its expression increases after two weeks of treatment with EGF/bFGF. Then, we analyzed the association of PrPC with gangliosides and EGF receptor (EGF-R) during neuronal differentiation process. PrPC associates constitutively with GM2 in control hDPSCs and with GD3 only after neuronal differentiation. Otherwise, EGF-R associates weakly in control hDPSCs and more markedly after neuronal differentiation. To analyze the functional role of PrPC in the signal pathway mediated by EGF/EGF-R, a siRNA PrP was applied to ablate PrPC and its function. The treatment with siRNA PrP significantly prevented Akt and ERK1/2 phosphorylation induced by EGF. Moreover, siRNA PrP treatment significantly prevented neuronal-specific antigens expression induced by EGF/bFGF, indicating that cellular prion protein is essential for EGF/bFGF-induced hDPSCs differentiation. These results suggest that PrPC interact with EGF-R within lipid rafts, playing a role in the multimolecular signaling complexes involved in hDPSCs neuronal differentiation.