Identification of Targets and Pathways Controlled by the Chicken MicroRNAs miR-10a and miR-143

Abstract

MicroRNAs are small non-coding RNAs that regulate gene expression at the posttranscriptional level. The importance of microRNAs in development, tumorogenesis, immune system function, and infectious diseases has gradually come to light. MicroRNAs are often expressed in a temporal and spatial manner and regulate specific gene sets to achieve phenotypic change. To understand the role of microRNAs in the chicken embryonic spleen, we have profiled microRNA expression at E15 and E20 chicken embryos. The objective of the current project is to identify the targets and pathways controlled by two microRNAs, miR-10a and miR-143. Target prediction was carried out by the algorithm miRanda. Eight predicted targets of each microRNA were subjected to validation using a reporter assay that incorporates synthetic or retroviral transduced microRNA. Validated targets for miR-143 known to have profound functions in apoptosis, T and B cell development and maturation, cancer, or adipocyte differentiation were identified with this approach; for miR-10a, validated targets involved in hematopoiesis, immune cells homing and migration and megakaryocyte differentiation were identified. Microarray analysis revealed that several targets not predicted by the algorithm were upregulated upon treatment with a specific microRNA inhibitor. This result suggests that both microRNAs may regulate genes that contribute to cancer formation. In addition, miR-10a may be involved in regulating the complement system, which is a crucial component of innate immunity; miR-143 may be involved in the PPAR/RXR pathway, which regulates glucose and lipid metabolism in cells. Taken together, our results suggest targets and pathways possibly regulated by miR-10a or miR-143. The inferred functions of the targets and pathways identified in our study are mostly consistent with those from previous studies, thereby providing insights and directions for future research into the mechanisms by which miR-10a and miR-143 exert their function in the developing chick embryo. Furthermore, the RCAS system used in this project also proved the usefulness of engineered retrovirus for transducing microRNA. Further development of this tool may aid microRNA research and further contribute to understanding of the role of microRNAs in vertebrate development.