Phosphatidylinositol 3-Kinase and Protein Kinase C Signaling Pathways Are Involved in Stromal Cell-derived Factor-1α-mediated Transmigration of Stem Cells from Apical Papilla.

INTRODUCTION

Previously, we have shown that stem cells from apical papilla (SCAPs) can be chemoattracted by stromal cell-derived factor-1α (SDF-1α). The purpose of this study was to investigate the intracellular signaling pathways involved in SDF-1α-mediated migration of SCAPs.

METHODS

Chemotaxis assays were performed to assess the effect of phosphatidylinositol 3-kinase (PI3K) and protein kinase C (PKC) signaling pathways in the SDF-1α-mediated migration of SCAPs using inhibitors of PI3K (LY294002) or PKC (GF109203X). The Cell Counting Kit-8 assay (Dojindo Laboratories, Kumamoto, Japan) was used to evaluate the effect of the inhibitors on the proliferation of SCAPs. The expression of focal adhesion-related proteins was examined by immunofluorescence staining and Western blot analysis. Phosphorylation of PI3K subunit p85 and PKC after SDF-1α induction was evaluated by Western blot.

RESULTS

The inhibition of PI3K or PKC signaling pathways significantly reduced SDF-1α-mediated migration of SCAPs. The inhibitors had no effect on the proliferation of SCAPs. Immunofluorescence analysis revealed that SDF-1α stimulated focal adhesion formation and stress fiber assembly in SCAPs, in addition to up-regulation of the expression of focal adhesion molecules, including p-focal adhesion kinase, p-paxillin, and vinculin. Pretreatment with PI3K or PKC inhibitors before SDF-1α induction significantly inhibited focal adhesion molecule expression. Moreover, increased phosphorylation of p85 and PKC were observed after SDF-1α stimulation, whereas these phosphorylations were down-regulated by the inhibition of PI3K or PKC signaling pathways.

CONCLUSIONS

PI3K and PKC signaling pathways appear to be required for SDF-1α-mediated transmigration of SCAPs. These findings provide insights into the signaling mechanisms that underlie SDF-1α-mediated migration of SCAPs.