A Novel Murine Experimental System for Analyzing Differentiation of Oligodendrocyte Precursor Cells Using Sox10‐Venus Mice

Abstract

In the central nervous system (CNS), myelin surrounding axons are formed by oligodendrocytes. Dysfunction of oligodendrocytes in CNS myelination results in neurological disorders, such as leukodystrophy and multiple sclerosis. However, the detailed mechanism of oligodendrocyte differentiation, including cellular process formation, and of myelination has not been elucidated yet, particularly since purification of oligodendrocyte precursor cells (OPCs) from mice, but not rats, is not efficient. We recently created and established a transgenic mouse line that expresses a fluorescent protein Venus driven by the promoter of the Sox10 gene. Endogenous Sox10 is specifically expressed in OPCs and oligodendrocytes in the CNS. In the present study, we have characterized Venus‐positive (+) cells from the brain of Sox10‐Venus mice for the analysis of oligodendrocyte differentiation. First, we purified Venus (+) cells from the brains at postnatal day 0–2, when OPCs have not differentiated into oligodendrocytes, by flow cytometry. Most Venus (+) cells expressed an OPC marker NG2, but not other glial cell markers including galactocerebroside (GalC), a marker for oligodendrocytes. After induction of differentiation with the serum‐free differentiation medium, an increase of GalC‐positive oligodendrocytes and decrease of NG2‐positive OPCs were observed in the Venus (+) culture. These results suggest that OPCs were efficiently purified and differentiated into oligodendrocytes using the Sox10‐Venus system. In addition, a time‐lapse analysis of the Venus (+) OPC differentiation was performed and showed that Venus (+) OPCs dynamically changed their cell morphology with highly branched cellular processes during their differentiation into oligodendrocytes. We further found that Venus (+) OPCs were differentiated into type II astrocytes with the serum‐containing differentiation medium. In vivo, Venus (+) cells expressed NG2 at P0 and both NG2 and myelin basic protein, an oligodendrocyte marker, at P20, when numerous oligodendrocytes are differentiated from OPCs and form myelin. Moreover, some of S‐100‐positive astrocytes expressed Venus in the ventral cortex. Together, the Sox10‐Venus mouse system is useful for analyzing differentiation and multipotency of murine OPCs.