title: Role of protein tyrosine phosphorylation in acetaldehyde-induced disruption of epithelial tight junctions.
abstract: Acetaldehyde-induced cytotoxicity is an important factor in pathogenesis of alcohol-related diseases; however, the mechanism of this toxicity is unknown. We recently showed that acetaldehyde increases epithelial paracellular permeability. We asked whether protein tyrosine phosphorylation via modulation of tyrosine kinases and/or PTPases is a mechanism involved in acetaldehyde-induced disruption of the tight junctions in the Caco-2 cell monolayer. Immunofluorescence localization of occludin and ZO-1 showed disruption of the tight junctions in acetaldehyde-treated cell monolayer. Administration of genistein prevented acetaldehyde-induced permeability. Acetaldehyde increased tyrosine phosphorylation of three clusters of proteins with molecular masses of 30-50, 60-90, and 110-150 kDa; three of these proteins were ZO-1, E-cadherin, and beta-catenin. Acetaldehyde reduced PTPase activity in plasma membrane and soluble fractions, whereas tyrosine kinase activity remained unaffected. Treatment with acetaldehyde resulted in a 97% loss of protein tyrosine phosphatase (PTP)1B activity and a partial reduction of PTP1C and PTP1D activities. These results strongly suggest that acetaldehyde inhibits PTPases to increase protein tyrosine phosphorylation, which may result in disruption of the tight junctions.
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston, SC 29425, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Atkinson
authors.forename: R K
authors.initials: RK
authors.lastname: Rao
mesh_terms: D000079:Acetaldehyde / Q000494:pharmacology*; D018938:Caco-2 Cells; D015820:Cadherins / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects* / Q000378:metabolism; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D010539:Permeability; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism; D015534:Trans-Activators; D014443:Tyrosine / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D010750:Phosphoproteins; C569042:TJP1 protein, human; D015534:Trans-Activators; D062826:Zonula Occludens-1 Protein; D051176:beta Catenin; D014443:Tyrosine; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D017027:Protein Tyrosine Phosphatases; D000079:Acetaldehyde