Roles of lysophosphatidic acid and the Rho-associated kinase pathway in the migration of dental pulp cells

During the dental pulp repair process, dental pulp cells (DPCs) migrate to the site of injury and differentiate into odontoblasts or odontoblast-like cells. Although migration of DPCs is an important reparative process, the underlying mechanism remains unknown. The objective of this study was to determine the roles of lysophosphatidic acid (LPA) and the Rho-associated kinase (ROCK) pathway in the migration and morphology of dental pulp cells and alpha smooth muscle actin expression in vitro. We demonstrated that both LPA and ROCK inhibition enhanced cell motility and that their combined effects significantly increased migration rate. LPA induced fine cytoskeleton assembly and increased the level of alpha smooth muscle actin (α-SMA). ROCK inhibition by Y-27632 and ROCK-(1+2) small interfering RNA (siRNA) resulted in less actin cytoskeleton formation, a lower α-SMA level, a star-like cellular morphology and membrane ruffling. LPA and ROCK inhibition induced activation of another Rho GTPase, Rac, which may explain how LPA and ROCK inhibition increases cellmigration and lamellipodium formation.