Alpha-tubulin relocalization is involved in calcium oxalate-induced tight junction disruption in renal epithelial cells

Microtubule (MT) is associated with tight junction (TJ) structure and function. While calcium oxalate monohydrate (COM) commonly causes TJ disruption, its effects on MT remain unknown. This study thus addressed the involvement of a major MT protein, α-tubulin, in COM-induced TJ disruption. Protein-protein interactions analysis demonstrated that α-tubulin directly interacted with a TJ protein, zonula occludens-1 (ZO-1). MDCK renal cells were polarized and incubated with COM crystals for 48 h. Western blotting showed that COM reduced ZO-1, but not α-tubulin, level. Immunofluorescence staining revealed COM-induced relocalization of α-tubulin from apical membranes to cytoplasm and ZO-1 disruption at cell borders. COM also mediated progressive fall of epithelial barrier function, represented by transepithelial resistance (TER), which reached the lowest at 12-h till the end of crystal exposure. Pretreatment of the cells with docetaxel, the MT/tubulin stabilizer, completely prevented such α-tubulin relocalization, ZO-1 disruption/down-regulation, and TER reduction. These data indicate that α-tubulin relocalization is involved in COM-induced TJ disruption in renal epithelial cells.