Comparative Functions of miRNAs in Embryonic Neurogenesis and Neuronal Network Formation

microRNAs (miRNAs) are small noncoding RNAs that act as posttranscriptional regulators of gene expression by triggering target mRNAs degradation or translational repression. Several studies show the importance of miRNAs in many developmental processes including neurogenesis. In multicellular organisms, most miRNAs are expressed in neural tissue and their dynamic spatiotemporal expression plays a key role in regulating multiple steps of neurogenesis. miRNAs are integrated into neural gene regulatory pathways and control processes such as neural stem cell proliferation, cell fate determination, and neuronal differentiation. In this chapter, we discuss the contribution of highly evolutionary conserved, neural-enriched miRNAs in shaping the central nervous systems of invertebrate and vertebrate model organisms focusing on their conserved and novel roles in controlling neurogenesis.