Abstract：microRNA-200b(miR-200b) has similar functions in regulating body size in mammals, while its exact roles has not been examined in mammals. To study the expression of miR-200b during the embryo development stage, and investigate the important roles of miR-200b and its target gene in regulating the body size of mouse, in this study, precursor miR-200b was amplified from the mouse(Mus musculus) genome DNA, RNA folding sofware was used to construct the secondary structure of miR-200b; potential target genes were predicted with bioinformatic software, and validated through Dual-luciferase reporter assay system; the expression profiles of miR-200b and its target gene Fog2 were detected using Real-time PCR in different tissues of adult mouse and embryos at the stage of 10.5~15.0 days after coitus. The results showed that the miR-200b precursor had the typical stem-loop structure of microRNA, and the Fog2 gene was predicted and tested to be a target gene of miR-200b, which showed negatively related expression to miR-200b in the embryos dpc10.5~15.0; qRT-PCR results showed that the miR-200b was expressed in almost all the tissues of female mouse, with higher expression in muscle, kidney and uterine, and lower expression in heart, spleen and lung tissues. From the expression profile and target gene testing results, we can conclude that miR-200b may play important roles in regulating mouse embryo development through acting with its target gene Fog2.
