miRNAs regulate acute transcriptional changes in broiler embryos in response to modification of incubation temperature.

MicroRNAs are post-transcriptional regulators that play critical roles in diverse biological processes. We hypothesize that miRNAs may be involved in regulating transcriptome responses to changes in embryonic incubation temperature in chickens affecting differentiation and proliferation processes during tissue development. Therefore, we conducted comparative transcriptome profiling of miRNAs to examine altered expression in breast and hind muscle of embryos and day 35 chickens experiencing high (38.8 °C), control (37.8 °C), or low (36.8 °C) embryonic incubation temperature during embryonic day (ED) 7-10 or ED10-13. The results revealed differential expression of miRNAs due to modification of embryonic incubation temperature in a muscle type-specific and a developmental stage-specific manner. The immediate effects of thermal change observed in embryos were substantial compared to the subtle long-term effects in chickens at day 35 post-hatch. Upregulation of miR-133 in breast muscle and downregulation of miR-199a-5p, miR-1915, and miR-638 in hind muscle post ED7-10 high-temperature treatment are functionally associated with myogenesis and body size. ED10-13 low-temperature treatment led to downregulation of let-7, miR-93, and miR-130c that are related to proliferation and differentiation. The results provide insight into the dynamics of miRNA expression at variable embryonic incubation temperatures during developmental processes and indicate a major regulatory role of miRNAs in acute responses to modified environmental conditions that affect remodelling of cells and tissues.