Epigenetic control of neural stem cell self-renewal. Maintenance of neural stem cells is normally associated with the repressive status of chromatin, which is represented by deacetylation of histones and methylation of histone H3 lysien 9 (K9). The repression is presumably resulted from recruitment of transcriptional corepressor complexes, including HDACs, MecP2, MBD, CoREST, to transcription factors at the promoter of target genes. Histone acetylation and methylation of histone H3 lysine 4 (K4) and lysine 20 (K20) are, on the other hand, involved in relaxation of chromatin structures and activation of lineage-specific gene expression, which in turn leads to differentiation of neural stem cells into mature neuron, astrocyte or oligodendrocyte. NSC stands for neural stem cells; Ac stands for histone acetylation.