Inhibition of Bcl-2 Stimulates Neural Stem Cell Proliferation in Organotypic Cultures of Mouse Hippocampus

The role of Bcl-1 in the proliferation and differentiation of hippocampal neural stem cells (NSC) was studied. Experiments were performed on organotypic cultures of mouse hippocampus. The selective Bcl-2 inhibitor HA14-1 (10 μM) was added to the incubation medium and its concentration was maintained at a constant level. The results showed that in the group with addition of HA14-1, the proportion of living cells was greater, and this was linked with higher levels of phosphohistone H3 and Oct3/4 expression, which is evidence for activation of NSC proliferation. At six weeks of incubation, addition of NA14-1 was associated with the formation of embryo-like bodies, which is evidence that dividing NSC do not undergo differentiation. The direction and level of NSC differentiation were assessed. The results showed that the level of CRMP-2 – a protein involved in axon growth – in the HA14-1 group decreased during NSC differentiation. The activity of ERK1/2 kinase of the MAPK signal cascade was determined, this providing indirect regulation of neuron differentiation. Decreases in ERK1/2 activity and CRMP-2 levels on addition of HA14-1 indicated inhibition of neuron differentiation. Thus, our studies showed that inhibition of Bcl-2 enhances the stimulation of NSC proliferation and provide evidence of the role of Bcl-2 in regulating the neuronal type of NSC differentiation.