Decrease in expression of alpha sub(5) beta sub(1) integrin during neuronal differentiation of cortical progenitor cells

Neuronal differentiation of embryonic neural progenitor cells is regulated by both intrinsic and extrinsic signals. Since dynamic changes in cell shape typify neuronal differentiation, cell adhesion molecules could be relevant to this process. Although it has been reported that fibronectin-integrin interactions are important for the proliferation of neural progenitor cells, little is known about the contribution of integrins to neuronal differentiation. In order to address this shortfall, we examined integrin expression on cortical progenitor cells by using immunohistochemistry and FACS analysis of cells in which GFP expression was driven by regulatory (promoter) regions of the nestin gene (nestin-GFP super(+)). We here report that high levels of nestin promoter activity correlated with high expression levels of alpha sub(5) beta sub(1) integrin ( alpha sub(5) beta 1high cells). FACS analysis of nestin-GFP super(+) cortical cells revealed an additional subpopulation with reduced expression of alpha sub(5) beta sub(1) integrin ( alpha sub(5) beta 1low cells). The size of the alpha sub(5) beta 1low subpopulation increased during cortical development. To investigate the correlation between integrin and neuronal differentiation, nestin-GFP super(+) cortical progenitor cells were sorted into alpha sub(5) beta 1high or alpha sub(5) beta 1low populations, and each potential to differentiate was analyzed. We show that the nestin-GFP super(+) alpha sub(5) beta 1high population corresponded to broadly multipotential neural progenitor cells, whereas nestin-GFP super(+) alpha sub(5) beta 1low cells appeared to be committed to a neuronal fate. These findings suggest that alpha sub(5) beta sub(1) expression on cortical progenitor cells is developmentally regulated and its downregulation is involved in the process of neuronal differentiation.