Figure 1.

Summary of exRNA communication in a parasitic nematode model. Top: H. polygyrus is a parasitic nematode that resides in the mouse small intestine. It releases an AGO protein and various types of small RNAs in its secreted product. Some of these AGO/small RNA complexes are found within vesicles. Bottom: Extracellular vesicles and/or AGO reach the epithelial cells of the mouse intestine, or other cell types, where they may have a variety of outcomes. Left: The H. polygyrus AGO/small RNA complexes could regulate gene expression in the host (in the nucleus or cytoplasm). Middle: Small RNAs from H.polygyrus could be incorporated into host AGO/RNAi pathways, where they can be used to influence host gene expression in the nucleus or cytoplasm. Right: Over time, small RNAs and target transcripts could co-evolve, leading to optimal manipulation of host gene expression by the parasite's exRNAs. In this example, the blue transcript is capable of being recognized by the blue exRNA, but not the red exRNA because they have co-evolved.