RBP‐J deficiency promoted the proliferation and differentiation of CD133‐positive cells in both in vitro and in vivo studies.

Although Notch signalling pathway could control the proliferation and differentiation of neural stem cells (NSCs), it is largely unknown about the effect of Notch signalling pathway on the neurogenesis of CD133‐positive cells. By using the primary cultured ependymal cells and the transgenic mouse, we found that CD133 immunoreactivity was exclusively localized in the ependymal layer of ventricles; moreover, most CD133‐positive cells were co‐labelled with Nestin. In addition, recombination signal binding protein J (RBP‐J), a key nuclear effector of Notch signalling pathway, was highly active in CD133‐positive cells. CD133‐positive cells can differentiate into the immature and mature neurons; in particular, the number of CD133‐positive cells differentiating into the immature and mature neurons was significantly increased following the deficiency or interference of RBP‐J in vivo or in vitro. By using real‐time qPCR and Western blot, we found that RBP‐J and Hes1 were downregulated, whereas Notch1 was upregulated in the expression levels of mRNAs and proteins following the deficiency or interference of RBP‐J. These results demonstrated RBP‐J deficiency promoted the proliferation and differentiation of CD133‐positive cells. Therefore, we speculated that RBP‐J could maintain CD133‐positive cells in the characteristics of NSCs possibly by regulating Notch1/RBP‐J/Hes1 pathway. It will provide a novel molecular insight into the function of RBP‐J as well as facilitate a future investigation of CD133‐positive cells with respect to their potential application in neurodegenerative disorder. [ABSTRACT FROM AUTHOR]