Emx2 promotes symmetric cell divisions and a multipotential fate in precursors from the cerebral cortex

Distinct sets of precursor cells generate the mammalian cerebral cortex. Du ring neurogenesis most precursors are specified to generate a single cell t ype and only few are multipotent. The cell-intrinsic molecular determinants of these distinct lineages are not known. Here we describe that retroviral transduction of the transcription factor Emx2 in precursors from the cereb ral cortex results in a significant increase of large clones that are gener ated mostly by symmetric cell divisions and contain multiple cell types, co mprising neurons and glial cells. Thus, Emx2 is the first cell-intrinsic de terminant able to instruct CNS precursors towards a multipotential fate. To evaluate the role of endogenous Emx2 in cortical precursors, we examined c ell division in Emx2-/- mice. These analyses further supported the role of endogenous Emx2 in the regulation of symmetric cell divisions in the develo ping cortex.