title: Ubiquitin E3 ligase A20 contributes to maintaining epithelial barrier function.
abstract: OBJECTIVE
  Epithelial barrier dysfunction is involved in the pathogenesis of allergic diseases; the mechanism is to be further understood. Ubiquitin E3 ligase A20 (A20) plays a role in maintaining the homeostasis in the body. This study aims to investigate the role of A20 in maintaining the epithelial barrier function.
  
  
  METHODS
  Human intestinal epithelial cell line, Caco-2 cells, was cultured to monolayers to test the endocytosis and degradation of a model allergen, ovalbumin (OVA). The role of A20 in the endosome/lysosome fusion in epithelial cells was tested with A20-sufficient and A20-deficient Caco-2 cells and visualized by immunocytochemistry.
  
  
  RESULTS
  Caco-2 cells could endocytose exogenous allergens (OVA) in culture. The endocytic OVA was degraded in A20-sufficient Caco-2 cells via the mechanism of endosome/lysosome fusion, while the A20-deficient Caco-2 monolayers converted the OVA to the basal compartment of transwells, which conserved the antigenicity reflected by that it induced T cell proliferation in an allergen-specific manner. A20 was required in the fusion of endosomes and lysosomes.
  
  
  CONCLUSIONS
  A20 contributes to maintaining the epithelial barrier function.
authors.affiliation: Department of Gastroenterology, the Shanghai Tenth People's Hospital, Tongji University, Shanghai, China.
authors.forename: Peixin
authors.initials: P
authors.lastname: Huang
authors.forename: Xiao-Rui
authors.initials: XR
authors.lastname: Geng
authors.forename: Gui
authors.initials: G
authors.lastname: Yang
authors.forename: Chi
authors.initials: C
authors.lastname: Chen
authors.forename: Zhanju
authors.initials: Z
authors.lastname: Liu
authors.forename: Ping-Chang
authors.initials: PC
authors.lastname: Yang
mesh_terms: D018938:Caco-2 Cells; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis / Q000187:drug effects; D011992:Endosomes / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010047:Ovalbumin / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3
chemical_list: D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D010047:Ovalbumin; C076529:TNFAIP3 protein, human; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3