Abstract
Purpose::
To investigate the expression of the neural progenitor marker Sox2 in MIO-M1 cells and to examine whether expression of this transcription factor is associated with the dividing and progenitor characteristics exhibited by these cells in vitro.
Methods::
MIO-M1 cells were cultured on different extracellular matrix (ECM) proteins in the presence of fibroblast growth factor 2 (FGF2). Expression of Sox2 was examined by confocal microscopy of immuno-stained cells and by western blotting and RT-PCR analyses. RNA interference was used to downregulate the expression of Sox2. For this purpose, two Sox2 silencer constructs and one scrambled construct were ligated into the pGUS-GFP vector. Characteristics of cells transfected with the shRNA constructs were examined by RT-PCR and confocal microscopy.
Results::
We showed that over 90% of MIO-M1 cells cultured on different ECM proteins expressed Sox2. This uniform expression was confirmed by western blotting and RT-PCR analyses. However, culture of these cells on certain matrix proteins in the presence of FGF2 caused a decrease in the expression of mRNA coding for this transcript. This decreased expression of Sox2 mRNA paralleled the aquisition of neural morphology by MIO-M1 cells. Knockdown of Sox2 also caused cells to adopt a neural morphology and to extend long axons within 24 hours of transfection.
Conclusions::
Since Sox2 is a well characterised marker of adult neural stem cells, the present observations that Sox2 is expressed by nearly all MIO-M1 cells in culture strongly suggests that these cells exhibit neural progenitor characteristics. Downregulation of Sox2 mRNA expression by differentiation under the influence of extracellular matrix and growth factors, as well as by transfection with shRNA suggest that this transcription factor may play an important role in conferring neural progenitor characteristics to MIO-M1 cells.
Keywords: gene/expression • transcription factors • differentiation