The Myxovirus Resistance Protein, MX1, Interacts with Tubulin Beta In Uterine Glandular Epithelial Cells

Problem MX proteins are upregulated during viral infection and during early pregnancy in ruminants by type I interferons and exhibit a number of characteristics that would suggest they function in basic cellular processes. We hypothesize MX1 plays a role in intracellular trafficking and secretion, and the objective of this study was to identify cellular proteins that interact with MX1. Method of study Western blot and polymerase chain reaction were used to detect expression of MX1 and endogenous interferon (IFN), respectively. Affinity chromatography and mass spectrometry identified proteins that interacted with MX1. These interactions were confirmed and characterized using co-immunoprecipitation and co-immunofluorescence. Results MX1 was expressed in ovine glandular epithelial cells without IFN treatment, while another interferon-stimulated gene, ISG15, was not. MX1 was shown to interact with tubulin beta (TUBB) during interphase and mitosis and nocodazole disrupted this interaction. Conclusion We propose that by tethering to TUBB, MX1 could be transporting proteins or vesicles throughout the cell, such as those destined for secretion or required for mitosis. This would be a novel role for an ISG, but one that is consistent with the enhanced secretion occurring in the uterus during early pregnancy in ruminants in response to conceptus-produced IFN-tau.