Neural Stem Cells and Neurogenic Niche in the Adult Brain

The discovery of adult neurogenesis has greatly advanced our knowledge of the human brain. During the past 50 years, the regulatory mechanisms and potential functions of this intriguing process have been extensively investigated. Our current knowledge supports the model that adult neurogenesis is regulated by both intrinsic genetic and epigenetic programs and extrinsic microenvironment and stimuli. This intricate molecular network has profound roles in controlling the self-renewal and multipotency of neural stem cells, the cellular basis of adult neurogenesis. In this review, we will summarize the current knowledge and our recent work in understanding adult neurogenesis with emphasis on answering two questions: how intrinsic epigenetic mechanisms, mediated through histone modifications, non-coding RNAs, and DNA methylation, define the signature of adult neural stem cells, and how extrinsic effects of growth factors, cytokines, and chemokines contribute to the adult neurogenic niche.