Tumor Necrosis Factor α-Converting Enzyme Mediates MUC5AC Mucin Expression in Cultured Human Airway Epithelial Cells

• Published in: Proceedings of the National Academy of Sciences - PNAS 2003-09, Vol.100 (20), p.11618-11623
• Main Authors: Matt X. G. Shao, Ueki, Iris F., Nadel, Jay A.
• Format: Article
• Language: English
• Subjects: ADAM Proteins; ADAM17 Protein; Base Sequence; Biological Sciences; Body fluids; Cell culture techniques; Cell Line; Cell lines; DNA Primers; Enzymes; Epithelial cells; Gene expression; Gene Expression Regulation - drug effects; Gene Expression Regulation - physiology; Humans; Ligands; Lipopolysaccharides - pharmacology; Lungs; Medical research; Messenger RNA; Metalloendopeptidases - metabolism; Metalloendopeptidases - physiology; Mucin 5AC; Mucins; Mucins - genetics; Phosphorylation; Pretreatment; Proteins; Receptor, Epidermal Growth Factor - metabolism; Respiratory Mucosa - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Small interfering RNA; Tetradecanoylphorbol Acetate - pharmacology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1534804100

Ectodomain shedding of epidermal growth factor receptor (EGFR) ligands [e.g., transforming growth factor type α(TGF-α)] and EGFR phosphorylation are implicated in mucin production in airway epithelial cells. Tumor necrosis factor a-converting enzyme (TACE) is reported to cleave precursor of TGF-α, with release of soluble mature TGF-α in various epithelial tissues. We hypothesized that TACE increases the shedding of TGF-α, 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-α-neutralizing Ab, implicating ligand (TGF-α)-dependent EGFR phosphorylation in mucin production. These stimuli induced release of soluble TGF-α, EGFR phosphorylation, and MUC5AC expression, which were blocked by the metalloprotease inhibitors tumor necrosis factor-α 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-α 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.