Cell to cell signalling via exosomes through esRNA

Abstract

Exosomes are small vesicles of endosomal origin that can be released by many different cells to the microenvironment. Exosomes have been shown to participate in the immune system, by mediating antigen presentation. We have recently shown the presence of both mRNA and microRNA in exosomes, specifically in exosomes derived from mast cells. This RNA can be transferred between one mast cell to another, most likely through fusion of the exosome to the recipient cell membrane. The delivered RNA is functional, as the mRNA can lead to translation of new proteins in a recipient cell. The RNA shuttled between cells via exosomes is called esRNA. We propose that several types of exosomes may exist, and that an additional function of exosomes is to communicate to neighbouring cells through delivery of RNA-signals.

Figure 1

Schematic presentation of different type of exosomes. Type 1 exosomes may be empty of RNA and could be primarily involved in antigen presentation and co-stimulation of other cells. We suggest that the type 2 exosomes contain substantial amounts of RNA, which may be involved in communication/synchronization with neighbouring cells.