Global MicroRNA Expression Profiling of Buffalo (Bubalus bubalis) Embryos at Different Developmental Stages Produced by Somatic Cell Nuclear Transfer and In-Vitro Fertilization Using RNA Sequencing

Despite the success of cloning technology in the production of offspring across several species, its application on a wide scale is severely limited by the very low offspring rate obtained with cloned embryos. The expression profile of microRNAs (miRNAs) in cloned embryos throughout embryonic development is reported to deviate from regular patterns. The present study is aimed at determining the dynamics of the global expression of miRNA profile in cloned and in-vitro fertilization (IVF) pre-implantation embryos at different developmental stages, i.e., the two-cell, eight-cell, and blastocyst stages, using next-generation sequencing. The results of this study suggest that there is a profound difference in global miRNA profile between cloned and IVF embryos. These differences are manifested throughout the course of embryonic development. The cloned embryos differ from their IVF counterparts in enriched Gene Ontology (GO) terms of biological process, molecular function, cellular component, and protein class categories in terms of the targets of differentially expressed miRNAs. The major pathways related to embryonic development, such as the Wnt signaling pathway, the apoptosis signaling pathway, the FGF signaling pathway, the p53 pathway, etc., were found to be affected in cloned relative to IVF embryos. Overall, these data reveal the distinct miRNA profile of cloned relative to IVF embryos, suggesting that the molecules or pathways affected may play an important role in cloned embryo development.