title: Neuropilin-1 is a receptor for extracellular miRNA and AGO2/miRNA complexes and mediates the internalization of miRNAs that modulate cell function.
abstract: Extracellular miRNAs are increasingly studied as markers for specific diseases. They are released in biological fluids in a remarkably stable form, and may play a role in intercellular communication. They are thought to be protected against degradation by either encapsulation within microparticles, or by binding to proteins (mostly AGO2). The particulate forms may be internalized by endocytosis or membrane fusion, but the protein-bound forms require a receptor mechanism for their uptake. A major question is whether there are natural cell-membrane receptors that capture and internalize protein-bound functional miRNAs. We examined neuropilin-1 (NRP1), in view of its properties as a receptor for many ligands, including growth factors such as vascular endothelial growth factor (VEGF), and efficiency at mediating ligand internalization. It is expressed by endothelial cells, many other normal cell types, and cancer cells. Here, we report that NRP1 binds miRNAs with high affinity, and promotes their entry into the cell. Furthermore, the internalized miRNAs remain functional, as they specifically regulate proliferation and migration of cancer cells, as well as tube formation by human endothelial cells. Anti-NRP1 antibodies or NRP1 siRNA knockdown block miRNA effects, further confirming NRP1-mediated uptake. VEGF does not compete with miRNAs for binding to NRP1. In addition, NRP1 binds extracellular AGO2 (carrying miRNA or not), and internalizes AGO2/miRNA complexes. Because miRNA bound to AGO2 appears to the most abundant form in body fluids, this may have important physiological and pathological effects.
authors.affiliation: Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.|Department of Laboratory Medicine, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.|Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5G 1L5, Canada.
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Prud'homme
authors.affiliation: Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.
authors.forename: Yelena
authors.initials: Y
authors.lastname: Glinka
authors.affiliation: Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Lichner
authors.affiliation: Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.|Department of Laboratory Medicine, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.|Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON M5G 1L5, Canada.
authors.forename: George M
authors.initials: GM
authors.lastname: Yousef
mesh_terms: D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation / Q000235:genetics; D002478:Cells, Cultured; D004705:Endocytosis; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000235:genetics; D039942:Neuropilin-1 / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D034622:RNA Interference; D015398:Signal Transduction / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: C466422:AGO2 protein, human; D060565:Argonaute Proteins; D035683:MicroRNAs; D042461:Vascular Endothelial Growth Factor A; D039942:Neuropilin-1
keywords: endocytosis; endothelial cells; miRNA; neuropilin; renal cell carcinoma