ID(ealizing) control of adult subventricular zone neural stem/precursor cell differentiation for CNS regeneration

The adult central nervous system (CNS) was considered a comparatively static tissue with little cell turnover. It is now well established that there is more plasticity than previously thought and that astrocytes act as neural stem/precursor cells (NSPCs) in the subventricular zone (SVZ). The discovery that these NSPCs can give rise to a limited number of new neurons, reactive astrocytes and oligodendrocytes contributing to brain repair in CNS disease, has raised hopes toward harnessing these cells for therapeutic interventions. Here, we will discuss the transcriptional control of adult NSPC differentiation into astrocytes in CNS disease focusing on the helix-loop-helix transcription factor protein family. In our recent study, we reported that elevated BMP-2 levels are translated into an increase in Id3 expression in adult NSPC subpopulations after cortical injury. Id3 then heterodimerizes with the basic helix-loop-helix transcription factor E47 and releases the E47-mediated repression of astrocyte-specific gene expression. Consequently, adult NSPCs preferentially differentiate into astrocytes. We believe that understanding the in vivo differentiation potential and the molecular underpinnings of NSPCs in the adult mammalian brain will help us to evaluate their contributions to brain repair and may lead to new concepts in treating human CNS diseases.