Myosin VI contributes to maintaining epithelial barrier function

BACKGROUND: Epithelial barrier dysfunction is associated with the pathogenesis of a number of immune inflammations; the etiology is not fully understood. The fusion of endosome/lysosome is a critical process in the degradation of endocytic antigens in epithelial cells. Recent reports indicate that myosin VI (myo6) is involved in the activities of endosomes. The present study aims to investigate the role of myo6 in epithelial barrier dysfunction. RESULTS: The endosome accumulation was observed in myo6-deficient Rmcs. More than 80% endosomes were fused with lysosomes in naïve Rmcs while less than 30% endosomes were fused with lysosomes in the myo6-deficient Rmcs. The myo6-deficient Rmc monolayers showed high permeability to a macromolecular antigen, ovalbumin, the latter still conserved the antigenicity, which induced strong T cell activation. CONCLUSIONS: We conclude that myo6 plays a critical role in the fusion of endosome/lysosome in Rmc epithelial cells. Deficiency of myo6 compromises the epithelial barrier function.