The Myxovirus-Resistance Protein, MX1, is a Component of Exosomes Secreted by Uterine Epithelial Cells

Problem Dairy cattle suffer from high percentages of early embryonic loss, and therefore, it is critical to study the function of the uterus at this time. We hypothesize that the antiviral protein, myxovirus resistance (MX)1, regulates secretion in uterine glandular cells during early pregnancy. Method of Study Uterine epithelial cells were used to study uterine function, in vitro. Sucrose gradients, Western blotting, and transmission electron microscopy were used to isolate and identify exosomes. Immunofluorescence and ceramide inhibitors were used for the characterization of exosomes. Results Myxovirus resistance1 was associated with exosomes and protected from proteases, indicating it was inside exosomes. MX1 partially colocalized with exosomal protein CD63, and a ceramide inhibitor reduced numbers of MX1-associated exosomes. Conclusion This study is the first to characterize MX1-associated exosomes, and we postulate that MX1 regulates secretion in epithelial cells by playing a role in exosome formation or trafficking.