The role of microRNAs in neural stem cells and neurogenesis.

Neural stem cells give rise to neurons through the process of neurogenesis, which includes neural stem cell proliferation, fate determination of new neurons, as well as the new neuron's migration, maturation and integration. Currently, neurogenesis is divided into two phases: embryonic and adult phases. Embryonic neurogenesis occurs at high levels to form the central nervous system. Adult neurogenesis has been consistently identified only in restricted regions and occurs at low levels. As the basic process for embryonic neurodevelopment and adult brain maintenance, neurogenesis is tightly regulated by many factors and pathways. MicroRNA, short non-coding RNA that regulates gene expression at the post-transcriptional level, appears to be involved in multiple steps of neurogenesis. This review summarizes the emerging role of microRNAs in regulating embryonic and adult neurogenesis, with a particular emphasis on the proliferation and differentiation of neural stem cells.