Golli Myelin Basic Proteins Regulate Oligodendroglial Progenitor Cell Migration through Voltage-Gated Ca2+ Influx

Migration of oligodendrocyte progenitor cells (OPCs) from proliferative zones to their final location in the brain is an essential step in nervous system development. Golli proteins, products of the myelin basic protein gene, can modulate voltage-gated Ca2+ uptake in OPCs during process extension and retraction. Given the importance of process extension/retraction on movement, the consequences of golli expression on OPC migration were examined in vivo and in vitro using time-lapse imaging of isolated OPCs and acute brain slice preparations from golli KO and golli J37 overexpressing mice (JOE). The results indicated that golli stimulated migration, and this enhanced motility was associated with increases in the activity of voltage operated Ca2+ channels (VOCCs). Activation of VOCCs by high K+ resulted in a significant increase in the migration speed of JOE OPCs versus control cells and golli-mediated modulation of OPC migration disappeared in the presence of VOCC antagonists. During migration, OPCs generated Ca2+ oscillations that were dependent on voltage-calcium influx and both the amplitude and frequency of these Ca2+ transients correlated positively with the rate of cell movement under a variety of pharmacological treatments. The Ca2+ transient amplitude and the rate of cell movement were significantly lower in KO cells and significantly higher in JOE cells suggesting that the presence of golli promotes OPC migration by increasing the size of voltage-mediated Ca2+ oscillations. These data define a new molecule that regulates Ca2+ homeostasis in OPCs, and are the first to demonstrate that voltage-gated Ca2+ channels can regulate an OPC function, such as migration.