Identification of a regulatory region which is involved in Sox-2 expression in embryonic and neural stem cells and its molecular basis

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We have been interested in understanding common properties between ES cells and neural stem cells such as self-renewal ability in a molecular level. To gain insight about it, we considered that it is important to identify a regulatory region which works in both of these two kinds of stem cells. Since it is known that Sox-2 gene is expressed in both ES cells and neural stem cells, we pursued the possibility that the Sox-2 gene bears such regulatory region. We have previously identified two enhancers, SRR1 and SRR2 based on their activities in pluripotent ES cells. In this context, we examined whether these Sox-2 regulatory regions exhibit their activities also in neural stem/progenitor cells. Indeed, experiments with nestin-positive cells derived from ES cells, neurosphere methods, and in utero electroporation in all cases revealed that both of SRR1 and SRR2 exert rather strong transcription stimulating activities in neural stem/progenitor cells as well as in ES cells. Moreover, as in the case of ES cells, activities of SRR1 and SRR2 in neural stem/progenitor cells are specific in their multipotent state and these enhancers lose their entire activities when neural stem/progenitor cells are induced to differentiate with serum. Mutagenesis analyses demonstrated that SRR2 exhibits its activities in these two different types of stem cells by utilizing a common core sequence. Our analyses also revealed that Brn-1-Sox-2 and Brn-2-Sox-2 complexes are involved in SRR2 activities in neural cells, while Oct-3/4-Sox-2 complex plays major role in ES cells.We also performed the transgenic analyses about the SRR2 enhancer. From these analyses, we found that the SRR2 do not function in neural stem/progenitor cells in general, but exerts its activity rather specifically in neural stem/progenitor cells residing in telencephalon.