Regulation of Store-Operated and Voltage-Operated Ca Channels in the Proliferation and Death of Oligodendrocyte Precursor Cells by Golli Proteins

Abstract

OPCs (oligodendrocyte precursor cells) express golli proteins which, through regulation of Ca 2+ influx, appear to be important in OPC process extension/retraction and migration. The aim of the present study was to examine further the role of golli in regulating OPC development. The effects of golli ablation and overexpression were examined in primary cultures of OPCs prepared from golli-KO (knockout) and JOE (golli J37-overexpressing) mice. In OPCs lacking golli, or overexpressing golli, differentiation induced by growth factor withdrawal was impaired. Proliferation analysis in the presence of PDGF (platelet-derived growth factor), revealed that golli enhanced the mitogen-stimulated proliferation of OPCs through activation of SOCCs (store-operated Ca 2+ channels). PDGF treatment induced a biphasic increase in OPC intracellular Ca 2+ , and golli specifically increased Ca 2+ influx during the second SOCC-dependent phase that followed the initial release of Ca 2+ from intracellular stores. This store-operated Ca 2+ uptake appeared to be essential for cell division, since specific SOCC antagonists completely blocked the effects of PDGF and golli on OPC proliferation. Additionally, in OPCs overexpressing golli, increased cell death was observed after mitogen withdrawal. This phenomenon could be prevented by exposure to VOCC (voltage-operated Ca 2+ channel) blockers, indicating that the effect of golli on cell death involved increased Ca 2+ influx through VOCCs. The results showed a clear effect of golli on OPC development and support a role for golli in modulating multiple Ca 2+ -regulatory events through VOCCs and SOCCs. Our results also suggest that PDGF engagement of its receptor resulting in OPC proliferation proceeds through activation of SOCCs.