Non-coding RNA Expression and Function in Pig Reproductive Tissues

MicroRNA (miRNA) are known to influence the mRNA and protein abundance through post-transcriptional gene regulation following interactions with the 3′UTR that lead to translation inhibition and/or mRNA degradation.  Reproductive tissues are comprised of dynamic cell types that undergo significant transcriptional and translational reorganization during gamete development, embryogenesis, during conceptus elongation and over the course of the estrous cycle and early pregnancy.  We utilized massively parallel deep sequencing using the SOLiD sequencing system to characterize small RNA expression in the maturing cumulus oocyte complex, early embryo development, elongating conceptus and in the uterine endometrium during the estrous cycle and early pregnancy in pigs. Numerous miRNA, piRNA and other small RNA molecules were identified and mapped them to the pig genome.  Following mapping and quantification of small RNA sequence reads, unique miRNA and piRNA clusters were identified in addition to multiple miRNA that are replicated throughout the genome.  Changes in total small RNA predicted to interact with specific mRNA were used to identify potential PTGR events in the oocyte following germinal vesicle breakdown in the oocyte during maturation.  Functional characterization of MIR21 and its ability to regulate two potential targets mRNA, PDCD4 and PTEN, was conducted in the maturing cumulus oocyte complex. Increased MIR21 expression during oocyte maturation is temporally associated with the PDCD4 protein suppression which was inhibited in the presence of an anti-MIR21 oligonucleotide.  This project was supported by National Research Initiative Competitive Grant no. 2008-35205-05309 and 2008-35205-18712 from the USDA National Institute of Food and Agriculture.