Regulation of Olig2 during astroglial differentiation in the subventricular zone of a cuprizone-induced demyelination mouse model.

The mammalian subventricular zone (SVZ) is the largest germinative zone of the adult brain. Progenitor cells generated from the SVZ play important roles during the remyelination process. To determine the functional role of Olig2 in regulating astroglial differentiation in the mouse SVZ, we used the cuprizone mouse model to investigate demyelination. We found that cuprizone administration significantly enhanced the expression of Olig2 and increased astroglial differentiation in the SVZ, as compared with control. Moreover, cytoplasmic translocation of Olig2 occurred after demyelination. In vitro studies further revealed that supplementation of culture media with growth factors enhanced the oligodendroglial differentiation of oligodendrocyte progenitor cells (OPCs), whereas serum alone promoted astroglial differentiation and cytoplasmic translocation of Olig2. Additionally, the expression levels of bone morphogenetic proteins 2 and 4 (BMP2 and BMP4) and inhibitor of DNA binding 2 and 4 (Id2 and Id4) were greatly elevated during astroglial differentiation. BMP inhibition by noggin suppressed the astroglial differentiation of OPCs. Our results indicate that Olig2 may serve as a key regulator during the directional differentiation of progenitor cells after demyelination. The BMP signaling pathway may contribute to the cytoplasmic translocation and altered expression of Olig2 during the remyelination process. These findings provide a better understanding of the mechanisms involved in remyelination.