The role of miR-16 in embryonic brain development

Abstract

Micro RNAs (miRNAs) are key players in post transcriptional gene regulatory processes. Upon binding to specific recognition sites harbored mainly in the 3’untranslated regions of their target mRNAs, miRNAs either mediate degradation of these target mRNAs or their translational inhibition (O’Brien et al. 2018). Due to the considerably large number of genes targeted by miRNAs, it is not surprising that they also play a role during brain development. Many aspects of neurogenesis and neuronal migration are controlled by miRNAs and consequently, the misregulation of miRNAs can lead to impairments in these processes. In this study, a miRNA expression analysis was performed to access the miRNA expression profile of the murine embryonic brain at different developmental stages. Based on that, the effect of miR-16 on embryonic brain development was studied in more detail. MiR-16 is part of the miR-15 miRNA family. Other members of this miRNA family have already been shown to be important during embryonic brain development, the role of miR-16, however, remained unclear. To study the exact role of miR-16 in these developmental processes in more detail, a general description of the phenotype caused by miR-16 overexpression was made. For this, miR-16 was overexpressed in vivo in the embryonic neocortex of the mouse brain by in utero electroporation, followed by a range of antibody stainings with different neuronal cell markers. This analysis revealed that miR-16 is an important regulator of neural differentiation. In addition, mRNA sequencing of miR-16 overexpressing neuronal cells was performed to reveal potential target genes of this miRNA. One of the predicted targets, Wee1, was validated by performing luciferase reporter assays, western blot analyses and RT-qPCR. Taken together, this study gives an overview of miRNA expression profiles during murine brain development and reveals miR-16 as important regulator of embryonic neurogenesis. Furthermore, the checkpoint kinase Wee1 was identified as a target of miR-16.