Figure 1. Myriad roles of OPCs in the brain.
OPCs play many roles in the brain beyond the production of oligodendrocytes. For example, OPCs have the ability to give rise to non-oligodendroglial lineage cells such as astrocytes and glioblastoma cells. OPCs also release neuromodulatory factors such as GABA, NG2, and Sema6 to mediate neuronal activity, function, and migration (box 1). Moreover, OPCs interact extensively with neuronal axons through multiple modalities, including the receipt of direct synaptic transmission and the engulfment of presynaptic inputs (box 2). OPCs also regulate blood-brain barrier integrity through direct interactions with pericytes (box 3). Finally, OPCs can perform immune cell-like functions, such as phagocytosing cellular debris and presenting antigen. Overall, this diversity of functions has led to a growing appreciation of OPCs as the multi-taskers of the brain.