Nestin expression is lost in a neural stem cell line through a mechanism involving the proteasome and Notch signalling.

Neural stem cells (NSCs) are believed to repair brain damage primarily through cell replacement: i.e., the ability to regenerate lost neurons and glia in a site-specific fashion. The neural stem cell line, MHP36, has been shown to have this capacity, but we have little idea of the molecular mechanisms that control the differentiation of such cells during brain repair. In this study we show that an early event in the differentiation of MHP36 cells, both in vivo and in vitro, is the loss of expression of the intermediate filament protein, nestin. We use a co-culture assay to show that loss of nestin is fast, being detectable after just 1 h and complete in 4 h, and is controlled by proteasome degradation rather than down-regulation of de novo nestin synthesis. We also show that nestin loss is regulated by Notch, and mediated by cell contact.