MiR-125b protects against ethanol-induced apoptosis in neural crest cells and mouse embryos by targeting Bak 1 and PUMA.

MicroRNAs are a class of small noncoding RNAs that have been implicated in regulation of a broad range of cellular and physiologic processes, including apoptosis. The objective of this study is to elucidate the roles of miR-125b in modulating ethanol-induced apoptosis in neural crest cells (NCCs) and mouse embryos. We found that treatment with ethanol resulted in a significant decrease in miR-125b expression in NCCs and in mouse embryos. We also validated that Bcl-2 antagonist killer 1 (Bak1) and p53-upregulated modulator of apoptosis (PUMA) are the direct targets of miR-125b in NCCs. In addition, over-expression of miR-125b significantly reduced ethanol-induced increase in Bak1 and PUMA protein expression, caspase-3 activation, and apoptosis in NCCs, indicating that miR-125b can modulate ethanol-induced apoptosis by the regulation of Bcl-2 and p53 pathways. Furthermore, microinjection of miR-125b mimic resulted in a significant increase in miR-125b expression and a decrease in the protein expression of Bak1 and PUMA in ethanol-exposed mouse embryos. Up-regulation of miR-125b also significantly reduced ethanol-induced caspase-3 activation and diminished ethanol-induced growth retardation in mouse embryos. This is the first demonstration that miR-125b can prevent ethanol-induced apoptosis and that microinjection of miRNA mimic can prevent ethanol-induced embryotoxicity.