GSE196356
Multiple knockout mouse models indicate a role of miR-124a in neuronal maturation
MicroRNA-124a (miR-124a) is one of the most abundantly expressed miroRNAs in the central nervous system (CNS) and encoded by three genomic loci of miR-124a-1/2/3 in mammals; however, its in vivo roles and mechanisms in neuronal development and function remain ambiguous. In the present study, we investigated the effect of loss of miR-124a on neuronal differentiation in mice and embryonic stem (ES) cells. Since primary miR-124a-3 shows a background level expression in the brain and we could not obtain miR-124a-1/2/3 triple knockout (TKO) mice by mating, we generated and analyzed miR-124a-1/2 double knockout (DKO) mice. We found that miR-124a-1/2 DKO mice exhibit perinatal lethality. RNA-sequencing analysis demonstrated that the expression levels of proneural and neuronal marker genes are almost unchanged between the control and miR-124a-1/2 DKO brains, while the genes related to neuronal synaptic formation and function were enriched in the down-regulated genes of the miR-124a-1/2 DKO brain. In addition, the transcription regulator Tardbp/TDP-43, whose loss leads to defects in neuronal maturation and function, was inactivated in the miR-124a-1/2 DKO brain. We next generated miR-124a-1/2/3 TKO ES cells by using the CRISPR-Cas9 system as an alternative to miR-124a-1/2/3 TKO mice. Phase-contrast microscopic, immunocytochemical, and gene expression analyses showed that miR-124a-1/2/3 TKO ES cell lines can differentiate into neurons. Collectively, these results suggest that miR-124a plays roles in neuronal maturation rather than neurogenesis in vivo, and may advance our understanding of functional roles of microRNAs in CNS development in vivo. Overall design: We performed RNA-sequencing analysis using total RNAs purified from control (miR-124a-1+/-) and miR-124a-1/2 DKO mouse brains at embryonic day 17.5 (E17.5) in triplicate.