title: Tumor necrosis factor alpha-converting enzyme mediates MUC5AC mucin expression in cultured human airway epithelial cells.
abstract: Ectodomain shedding of epidermal growth factor receptor (EGFR) ligands [e.g., transforming growth factor type alpha (TGF-alpha)] and EGFR phosphorylation are implicated in mucin production in airway epithelial cells. Tumor necrosis factor alpha-converting enzyme (TACE) is reported to cleave precursor of TGF-alpha, with release of soluble mature TGF-alpha in various epithelial tissues. We hypothesized that TACE increases the shedding of TGF-alpha, resulting in EGFR phosphorylation and inducing mucin production in human airway epithelial (NCI-H292) cells. To examine this hypothesis, we stimulated NCI-H292 cells with phorbol 12-myristate 13-acetate (PMA, an activator of TACE) and pathophysiologic stimuli [lipopolysaccharide (LPS) and supernatant from the Gram-negative bacterium Pseudomonas aeruginosa (PA sup)]. PMA, PA sup, and LPS increased MUC5AC gene expression and mucin protein production, effects that were prevented by pretreatment with AG1478, a selective inhibitor of EGFR phosphorylation and by preincubation with an EGFR-neutralizing Ab or with a TGF-alpha-neutralizing Ab, implicating ligand (TGF-alpha)-dependent EGFR phosphorylation in mucin production. These stimuli induced release of soluble TGF-alpha, EGFR phosphorylation, and MUC5AC expression, which were blocked by the metalloprotease inhibitors tumor necrosis factor-alpha protease inhibitor-1 and tissue inhibitor of metalloprotease-3. We specifically knocked down the expression of metalloprotease TACE by using small interfering RNA for TACE. Knockdown of TACE inhibited PMA-, PA sup-, and LPS-induced TGF-alpha shedding, EGFR phosphorylation, and mucin production. From these results, we conclude that TACE plays a critical role in mucin production by airway epithelial cells by means of a TACE ligand-EGFR cascade in response to various stimuli.
authors.affiliation: Cardiovascular Research Institute and Departments of Medicine and Physiology, University of California, San Francisco, CA 94143-0130, USA.
authors.forename: Matt X G
authors.initials: MX
authors.lastname: Shao
authors.forename: Iris F
authors.initials: IF
authors.lastname: Ueki
authors.forename: Jay A
authors.initials: JA
authors.lastname: Nadel
mesh_terms: D051722:ADAM Proteins; D000072198:ADAM17 Protein; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D066246:ErbB Receptors / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008666:Metalloendopeptidases / Q000378:metabolism / Q000502:physiology*; D055271:Mucin 5AC; D009077:Mucins / Q000235:genetics*; D010766:Phosphorylation; D020545:Respiratory Mucosa / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D017931:DNA Primers; D008070:Lipopolysaccharides; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D009077:Mucins; D066246:ErbB Receptors; D051722:ADAM Proteins; D008666:Metalloendopeptidases; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; D013755:Tetradecanoylphorbol Acetate