Free Extracellular miRNA Functionally Targets Cells by Targeting Exosomes from Their Companion Cells

A Yale-led research team has described a novel pathway for the delivery of microRNA (miRNA), the tiny RNA molecules that can move between cells to regulate gene expression. The study was published online on April 29, 2015 in the open-access journal PLOS ONE. Scientists had previously described how miRNA transfers genetic regulatory information from cell to cell within protective nano-vesicles (sacs) known as exosomes. In this study, the Yale team — led by Professorof Medicine (Immunology) Philip Askenase (photo), M.D., in collaboration with visiting Professor Krzysztof Bryniarski from Jagiellonian University in Krakow, Poland — examined how miRNAs from mouse immune T cells are delivered independently of these exosome vesicles. Although such “free” extracellular RNA, or exRNA, is the dominant form of RNA in the circulation, the function of exRNA was not known. However, the researchers discovered that exRNA can associatewith exosomes from companion cells of the targeted cells (in this case, companion immune system B cells) to transfer the genetic messages via specific structures (antigens) on the final targeted cell. The findings are significant, say the researchers, because they show, not only how freely circulating miRNA transfers between cells, but also how it can influence the function of targeted cells in an antigen-specific way. The research provides a model for future study of miRNA information transfer between cells, and as a basis for the potential development of unique RNA genetic therapies for human diseases, including allergy, autoimmunity, and even cancer. Other authors of the PLOS ONE article include Wlodzimierz Ptak, Katarzyna Nazimek, Emilia Martin, Marian Szczepanik, and Marek Sanak. The Yale press release for this news was written by Ziba Kashef.
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