ASTROCYTE AND MICROGLIAL MOTILITY IN-VITRO IS FUNCTIONALLY DEPENDENT ON THE HYALURONAN RECEPTOR RHAMM

RHAMM (Receptor for Hyaluronic Acid Mediated Motility) has been identi fied as a receptor for the extracellular matrix component hyaluronan ( HA) and was recently shown to be essential for the locomotion of norma l and transformed peripheral cells. Until. now the potential role of R HAMM in the motility of neural-derived cells has not been investigated . Here, we report that cultured primary astrocytes, astrocyte cell lin es, and microglia express this receptor and exhibit RHAMM-dependent mo tility. Immunocytochemical localization of RHAMM showed that it was of ten present as aggregates at the periphery of cells in contact with on e another or concentrated on protruding processes of isolated cells. G lial cells contained 50 and 72 kDa forms of RHAMM, and both of these f orms were found to have HA binding capacity. Time lapse imaging of cel l locomotion revealed a significant inhibition of motility and process elongation by neutralizing anti-RHAMM antibodies and by peptides corr esponding to the HA binding domains of RHAMM. These results demonstrat e that RHAMM serves a role in glial cell locomotion in vitro and provi de the basis for investigations of the motile behavior of glial cells in vivo after CNS injury. (C) 1994 Wiley-Liss, Inc.