Regulatory mechanism of microRNA-155 in chicken embryo fibroblasts in response to reticuloendotheliosis virus infection.

Reticuloendotheliosis virus (REV) infection of multiple avian species can lead to a number of diseases such as runting syndrome, immunosuppression and oncogenesis, causing major economic losses. MicroRNAs play important roles in post-transcriptional regulation, effectively inhibiting protein synthesis, and participating in many biological processes in cells, including proliferation, differentiation, apoptosis, lipometabolism, virus infection and replication, and tumorigenesis. Based on our previous high-throughput sequencing results, we explore the regulatory mechanisms of microRNA-155(miR-155) in chicken embryo fibroblasts (CEFs) in response to REV infection. Our results revealed expression of miR-155 in CEFs after REV infection upregulated in a time- and dose-dependent manner, indicating miR-155 plays a role in REV infection in CEFs indeed. After transfected with miR-155-mimic and miR-155-inhibitor, we found overexpression of miR-155 targeted caspase-6 and FOXO3a to inhibit apoptosis and accelerate cell cycle, thus improving viability of REV-infected CEFs. This result also verified the protective role of miR-155 in the viability of CEFs in the presence of REV. Knockdown of miR-155 also supported these above conclusions. Our findings uncover a new mechanism of REV pathogenesis in CEFs, and also provide a theoretical basis for uncovering new effective treatment and prevention methods for RE based on miR-155.