AN IN VIVO GENETIC APPROACH TO THE ROLE AND MECHANISMS OF ACTION OF THE TRANSCRIPTION FACTOR SOX-2 IN NEURAL STEM CELLS: CONDITIONAL CELL TYPE-SPECIFIC, DEVELOPMENTALLY INDUCIBLE DELETION OF SOX-2

Neural stem cells are a great hope for the treatment of neurodegenerative disease. They are able to proliferate in an undifferentiated state (in culture, and in the nervous system, where they normally reside) as well as to generate differentiated (and functional) neurons and glia. A deeper understanding of the basic genetic mechanisms that control the genesis, maintenance and differentiation of neural stem cells is fundamental for their future therapeutic use. We wish to investigate the role of a transcription factor, Sox2, in the function and maintenance of neural stem cells. Previous studies in our laboratory showed that decreasing Sox2 levels in neural stem cells leads to defects in their function. Complete loss of Sox2 activity is lethal for early embryos, before neurogenesis. We wish to investigate the effects of complete loss of Sox2 in neural stem cells; so, we will generate by genetic manipulation a Sox2 gene (Sox2 flox) modified in such a way that it can be removed (excised) by an enzyme, CreERT2, that can be activated by administration of the drug tamoxifen. This enzyme will be produced in neural cells by an appropriate transgene. Thus, in mice expressing Sox2 flox and CreERT2, we will obtain the ablation of Sox2 in neural stem cells, in vivo or in culture, at specific stages of their proliferation or differentiation, allowing to identify all its roles in these cells. Further, the comparison of gene expression profiles in normal neural stem cells versus those lacking Sox2 will allow to identify genes controlled by Sox2. Finally, Sox2 appears to be important in the development of human inherited neural defects; in our previous mouse model, we find neurodegeneration with inclusions, in some brain areas, reminescent of those found in Parkinson’s and Alzheimer’s disease. Thus, we will investigate, using this new genetic system, the effects os Sox2 deficiency also in neurons.