Guidance Of Olfactory Ensheathing Cells Migration By Slit-2

Olfactory ensheathing cells(OECs) are a unique type of glial cells that have axonal growth-promoting properties.OEC transplantation has emerged as a promising experimental therapy of axonal injuries and demyelinating diseases.Olfactory ensheathing cells(OECs) migrate from olfactory epithelium towards olfactory bulb(OB) during development and provide a substrate for the extension of associated axons. However,the guidance mechanism for OEC migration remains a mystery.In this study,we firstly established single-cell migration assay to study the motility of OECs.We found that the distinct OEC subpopulations exhibited different migratory properties based on time-lapse imaging of single isolated cells,possibly due to their different cytoskeletal organizations.Moreover,OEC subpopulations displayed different attractive migratory responses to a gradient of lysophosphatidic acid(LPA) in sing/e-cell migration assays.Finally,we found that OEC subpopulations transformed into each other spontaneously.Together,these results demonstrate,for the first time to our knowledge,that distinct OEC subpopulations display different migratory properties in vitro and provide new evidence to support the notion of OECs as a single cell type with malleable functional phenotypes.Furthermore,we observed the expression of the Slit receptor Robos in OECs.In dissociated culture of migrating OECs,a frontal gradient of Slit-2 caused the collapse of the leading front and reversal of cell migration in a Ca²⁺-dependent manner.The collapse of the leading front in response to Slit-2 was preceded by a rapid loss of F-actin in cell periphery,possibly due to the activation of the F-actin-severing protein cofilin, while the reversal of soma migration depended on both collapse of the leading front and intracellular RhoA activity.Interestingly,the Slit-2-induced collapse and reversal migration of OECs were fully mimicked by a frontal gradient of a mixture of inhibitors for F-actin polymerization and RhoA signaling.Thus Slit-2 may guide the OEC migration through coordinated local disruption of F-actin at ceil periphery by activating cofilin and global reversal of cell polarity by inhibiting RhoA.