Primary cilia mediate sonic hedgehog signaling to regulate neuronal-like differentiation of bone mesenchymal stem cells for resveratrol induction in vitro.

Mesenchymal stem cells (MSCs) can differentiate into neuronal-like cell types under specific conditions. The classical antioxidant inducers such as β-mercaptoethanol (BME), butylated hydroxyanisol (BHA), and dimethylsulfoxide (DMSO) are limited in clinical because of toxicity. Resveratrol, a safer, natural antioxidant, can stimulate osteoblastic differentiation of MSCs. However, its effect of inducing MSCs to differentiate into neuronal-like cells is less well studied, and its differentiated mechanisms are not well understood. Sonic hedgehog (Shh) signaling, mediated by the primary cilia, is crucial for embryonic development and tissue differentiation, but relatively little is known about the role of Shh signaling and primary cilia in neuronal-like differentiation of MSCs. Here we show that primary cilia, harboring patched 1 (Ptc1), are present in growth-arrested MSCs and that smoothened (Smo) and Gli1 are present in cytoplasm of MSCs, which are important components of the Shh signaling pathway. After resveratrol induction, MSCs acquire neuronal-like cell morphologies and phenotypes, Smo translocates to the primary cilia, Gli1 enters the nucleus, and expressions of Smo and Gli1 proteins increase, which can be inhibited by cyclopamine, a Smo antagonist. Meanwhile, Smo agonist (SAG) attains similar effects compared with the resveratrol group. These data indicate that resveratrol can induce MSCs to differentiate into neuronal-like cells and activate Shh signaling pathway in the primary cilia. Moreover, the primary cilia and Shh signaling are essential for resveratrol inducing neuronal-like differentiation of MSCs. Our finding is important for understanding the neuronal-like differentiation mechanism of MSCs for resveratrol and promoting its clinical therapeutic utility.