ABSTRACT: Micro RNAs (miRNA) are short, endogenous non-coding RNAs, they function via base pairing with complementary sequences with their targets. With the current advance in modern technologies including Next Generation Sequencing, miRNAs have rapidly emerged as important regulators in various functions in cell proliferation, differentiation, cell death and metabolisms. miRNAs showed specifically important roles in central nerve system development with specific temporal spatial regulation, such as neuronal cell proliferation, neuronal differentiation, cell fate determination, axon outgrowth, dendritogenesis, synaptogenesis, and gliogenesis, neuronal guidance to form neuronal circuits. In this study, we will first focus on how microRNA regulates neuronal specification, proliferation and differentiation by investigating microRNA profiling in Dorsal Root Ganglion (DRG) at different embryonic stages both in chickens and mice. Second, we will investigate how the microRNA expression correlates with important transcription factors and neurotrophic factor receptors during the neuron cell specification, such as Runx3, TrkC. Third, we study the regulated miRNA targets and their impact on neurogenesis and development. Last, we will study how conserved roles of miRNA between mouse and chicken in the neuro-specification. We found dramatic reduction of large amount miRNA during specific embryonic stage. Their target genes overrepresent dentrites, synaps and neurogenesis genes, as well as genes largely involved in transcription. The study shows the importance of miRNA in neuronal development, and they function in cohort, buffered, flexible manner.
