title: Correlation between the destruction of tight junction by patulin treatment and increase of phosphorylation of ZO-1 in Caco-2 human colon cancer cells.
abstract: Patulin is a mycotoxin and its contamination of food has been reported to cause gastrointestinal inflammation, ulcers, and bleeding. The toxicity of patulin is thought to be due to the destruction of tight junctions (TJs) in gastrointestinal tissues. However, the precise mechanism has not been clarified. Here, we investigated the phosphorylation of TJ components. The transepithelial electrical resistance (TER) of Caco-2 human colon cancer cells decreased gradually during the first 24h of treatment with 50μM patulin. Immunofluorescence microscopy showed that the TJ proteins ZO-1 and claudin-4, but not occludin, had decreased after 24h and decreased from the cell-cell contact regions of TJs after 48h of patulin treatment. Western blotting showed that the level of ZO-1 decreased after 48h of patulin treatment, but the levels of claudin-4 and occludin remained at the initial level until 72h. Phosphorylation of ZO-1 was detected by 24h and increased markedly after 72h of patulin treatment. However, phosphorylation of claudin-4 and occludin was not detected by probing with anti-phosphotyrosine antibody. Immunoprecipitation showed that interaction of ZO-1 with claudin-4 had decreased after 48h and was completely absent after 72h. These results suggest that phosphorylation caused the degradation of ZO-1 protein and the decrease in TER induced by patulin treatment of Caco-2 cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kawauchiya
authors.forename: Ryo
authors.initials: R
authors.lastname: Takumi
authors.forename: Yukako
authors.initials: Y
authors.lastname: Kudo
authors.forename: Akiko
authors.initials: A
authors.lastname: Takamori
authors.forename: Tatuya
authors.initials: T
authors.lastname: Sasagawa
authors.forename: Kohei
authors.initials: K
authors.lastname: Takahashi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kikuchi
mesh_terms: D015153:Blotting, Western; D018938:Caco-2 Cells; D018929:Cell Culture Techniques; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010365:Patulin / Q000633:toxicity*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism; D062826:Zonula Occludens-1 Protein
chemical_list: D008565:Membrane Proteins; D010750:Phosphoproteins; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein; D010365:Patulin