Differential gene expression in oligodendrocyte progenitor cells, oligodendrocytes and type II astrocytes

Oligodendrocyte precursor cells (OPCs) are bipotential progenitor cells that can differentiate into myelin-forming oligodendrocytes or functionally undetermined type II astrocytes. Transplantation of OPCs is an attractive therapy for demyelinating diseases. However, due to their bipotential differentiation potential, the majority of OPCs differentiate into astrocytes at transplanted sites. It is therefore important to understand the molecular mechanisms that regulate the transition from OPCs to oligodendrocytes or astrocytes. In this study, we isolated OPCs from the spinal cords of rat embryos (16 days old) and induced them to differentiate into oligodendrocytes or type II astrocytes in the absence or presence of 10% fetal bovine serum, respectively. RNAs were extracted from each cell population and hybridized to GeneChip with 28,700 rat genes. Using the criterion of fold change > 4 in the expression level, we identified 83 genes that were up-regulated and 89 genes that were down-regulated in oligodendrocytes, and 92 genes that were up-regulated and 86 that were down-regulated in type II astrocytes compared with OPCs. The up-regulated genes, such as activating transcription factor 3 and myelin basic protein in oligodendrocytes or claudin 11 in type II astrocytes, might contribute to OPC differentiation and represent constitutive components of oligodendrocytes or type II astrocytes. The down-regulated genes in both oligodendrocytes and type II astrocytes, such as transcription factor 19, might be involved in maintaining self-renewal and/or represent the property of OPCs. These results provide new insights into the elucidation of the molecular mechanisms, by which OPCs differentiate to oligodendrocytes or type II astrocytes.