MicroRNA-221-5p Promotes Ricin Toxin-induced Inflammation via PI3K/Akt signaling pathway by targeting COL4a5

Ricin toxin (RT) is one of the most lethal type II ribosome-inactivating proteins (RIP), and is classified as a potential bioterror agent due to its severe cytotoxicity and high availability. The toxicity of RT is dependent on both dose and route of exposure. Increasing evidence demonstrates that sub-lethal RT induces acute inflammation and increases the release of pro-inflammatory cytokines. However, current studies on mechanism of RTinduced inflammation are limited. In this study, to evaluate the relationship between miRNAs and RT-induced inflammation, RNA sequencing (RNA-Seq) was used to analyze the expression of miRNAs and mRNAs in RTtreated RAW264.7 macrophage cells. A total of 14 significantly differently expressed (DE) miRNAs and 323 miRNA-mRNA interaction pairs were predicted by bioinformatics analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that majority of those interaction pairs were involved in PI3K/Akt pathway. In addition, overexpression of miR-221-5p promoted the inflammatory response by inhibiting the mRNA expression of COL4a5. This work contributes to our understanding of RT-induced inflammation and demonstrates the potential role of miRNAs in innate immunity, which may be regarded as potential targets in developing therapies for RT poisoning.