PKCε induces astrocytic differentiation of multipotential neural precursor cells

In this study, we examined the role of PKC in the differentiation of multipotential neural precursor cells (NPCs). We found that the NPCs expressed PKC alpha,beta 2,delta,epsilon,zeta and low levels of PKC gamma. The PKC activator, PMA, selectively increased the number of astrocytes, whereas it decreased the generation of neurons and oligodendrocytes. Similarly, overexpression of PKC epsilon increased the differentiation of astrocytes and a PKC epsilon KD mutant abolished PMA effect. PMA phosphorylates PKC epsilon; on serine 729. Using a PKC epsilon S729A mutant, we found that the phosphorylation of PKC epsilon on serine 729 was essential for the differentiation of astrocytes induced by PMA. To delineate the mechanisms involved in PMA and PKC epsilon effects, we examined the expression of Notch1, which has been associated with astrocytic differentiation. We found that PMA and PKC epsilon induced a large increase in Notch1 expression and the PKC epsilon S729A mutant abolished PMA effect. Moreover, the PKC epsilon S729A mutant also inhibited the effect of CNTF on astrocytic differentiation and Notch1 expression. Finally, Notch1 mediated the effect of PMA on astrocytic differentiation, since the gamma-secretase inhibitor L-685,458, and Notch1 silencing abolished PMA effect. Our data suggest an important role of PKC epsilon in astrocytic differentiation and implicate Notch1 as a possible mediator of this effect. (c) 2006 Wiley-Liss, Inc.