- Open Access
IL-4 induced MUC4 enhancement in respiratory epithelial cells in vitro is mediated through JAK-3 selective signaling
© Damera et al. 2006
- Received: 19 November 2005
- Accepted: 21 March 2006
- Published: 21 March 2006
Recent studies have identified MUC4 mucin as a ligand for activation of ErbB2, a receptor tyrosine kinase that modulates epithelial cell proliferation following epithelial damage in airways of asthmatics. In this study, we investigated the potential role of IL-4, one of the Th2 inflammatory cytokines persistent in asthmatic airways, in regulating MUC4 expression using a cell line NCI-H650.
Real time PCR analysis was performed to determine concentration and time dependent effects of IL-4 upon MUC4 expression. Nuclear run on experiments were carried out to explore potential transcriptional modulation. Western blotting experiments using a monoclonal antibody specific to ASGP-2 domain of MUC4 were performed to analyze MUC4 glycoprotein levels in plasma membrane fractions. To analyze potential signal transduction cascades, IL-4 treated confluent cultures were co-incubated, separately with a pan-JAK inhibitor, a JAK-3 selective inhibitor or a MEK-1, 2 (MAPK) inhibitor at various concentrations before MUC4 transcript analysis. Corresponding transcription factor activation was tested by western blotting using a monoclonal p-STAT-6 antibody.
MUC4 levels increased in a concentration and time specific fashion reaching peak expression at 2.5 ng/ml and 8 h. Nuclear run on experiments revealed transcriptional enhancement. Corresponding increases in MUC4 glycoprotein levels were observed in plasma membrane fractions. Pan-JAK inhibitor revealed marked reduction in IL-4 stimulated MUC4 levels and JAK3 selective inhibitor down-regulated MUC4 mRNA expression in a concentration-dependent fashion. In accordance with the above observations, STAT-6 activation was detected within 5 minutes of IL-4 stimulus. No effect in MUC4 levels was observed on using a MAPK inhibitor.
These observations signify a potential role for IL-4 in MUC4 up-regulation in airway epithelia.
- Neutrophil Elastase
- MUC4 Expression
- Normal Human Bronchial Epithelial
- MUC4 mRNA
- Plasma Protein Fraction
Allergic asthma is an IgE-mediated condition characterized by airway hyper-responsiveness (AHR), chronic airway inflammation and epithelial cell damage [1–3]. These changes in the airways are associated with increased influx of activated CD4+ T-helper (Th) lymphocytes, which in turn, recruit eosinophils via the production of inflammatory mediators, including cytokines (IL-4 and IL-5) and chemokines (eotaxin) [4–7]. The eosinophils upon activation and recruitment cause epithelial cell damage by release of cytotoxic proteins [8–10]. Following tissue damage, the process of epithelial cell proliferation and restitution is broadly attributed to a subclass of receptor tyrosine kinases (RTK) called the ErbB's [11, 12]. ErbB family of receptors is composed of four members, namely ErbB1, ErbB2, ErbB3 and ErbB4. Phosphorylation of ErbB receptors by ligand binding induces heterodimerization and activation of specific signaling cascades. The ligands for these receptors are epidermal growth factor (EGF) conserved peptide growth factors . In this context, MUC4, an airway mucin with EGF-like domains in its transmembrane subunit, has been identified as a possible ligand for ErbB2 receptor .
MUC4 is a large molecular weight membrane bound O-glycoprotein expressed in the ciliated and goblet cells of the trachea and bronchus . Beyond the respiratory tract, MUC4 is present in the epithelial tissues of stomach, breast, endocervix, cornea and colon [16, 17]. Structurally, MUC4 is a heterodimeric complex consisting of a large 850 kD membrane bound MUC4α subunit and a smaller 80 kD trans-membrane MUC4β subunit . The larger MUC4α subunit is believed to exhibit anti-adhesive properties and to protect the apical surfaces of epithelial cells . In contrast, MUC4β subunit possesses two EGF-like domains that bind to ErbB2 receptors and modulates epithelial cell proliferation or differentiation . However, some reports indicate the presence of three EGF domains in the trans-membrane subunit .
Clinical and experimental evidence suggests a central role for IL-4 in the development and maintenance of AHR in allergic asthmatics . IL-4 is also reported to play a significant role in secretory cell metaplasia increasing the area of mucus secreting cells in airways. For instance, separate studies with transgenic mice distinctively expressing IL-4 in the lungs showed goblet cell metaplasia , allergen challenged STAT-6-deficient mice (IL-4R signaling-impaired mouse airways) showed a marked reduction in the same phenomenon . Furthermore, IL-4 was reported to enhance mucus production in cultured airway epithelial cell line NCI-H292 and to up-regulate MUC genes in mouse airways .
Earlier, studies involving MUC genes were performed to explain a mucus hypersecretory phenotype in chronic airway inflammatory states. Consequently, those studies explored the effects of cytokines and proteolytic enzymes upon a variety of secretory mucin genes including MUC2, MUC5AC, MUC5B and MUC8. Findings from these studies revealed a direct effect of inflammatory mediators upon MUC gene regulation; nevertheless, ambiguity persists, as to whether the regulatory pattern is exclusive to a few or uniform across all known airway mucin genes. For example, IL-4 decreases MUC5AC and increases MUC8 levels in cultured human nasal epithelial cells ; IL-9 increases MUC2 and MUC5AC expression and has no effect on MUC8 and MUC5B genes in bronchial epithelial cells ; IL-13 was reported to increase MUC2 and decrease MUC5AC expression in-vitro . Further, the effects of these inflammatory mediators on membrane-bound mucins are not yet defined.
In a previous study, we demonstrated the effects of secretagogues, such as 8-bromocyclic AMP and neutrophil elastase, on mucin secretions using a lung cancer cell line, NCI-H650 . Utilizing the same cell line in the present study, we investigated the effects of IL-4 upon MUC4 gene and glycoprotein expression. Regulation was established to be at the transcriptional level. Using a variety of signaling inhibitors we investigated the activation of janus kinase (JAK) and mitogen-activated protein kinase (MAPK) pathways. We further emphasized the phosphorylation of the related transcription factor, STAT-6.
The human bronchoalveolar carcinoma cell line NCI-H650 (ATCC, Manassas, VA) was cultured in serum free ACL-4 media supplemented with 2 mM glutamine, 100 U/ml penicillin, 100 μg/ml streptomycin and 0.02 mg/ml insulin. Cells were grown at 37°C in CO2 fully humidified air and were sub-cultured twice weekly. The cell viability was periodically determined by trypan blue exclusion method.
The confluent cultures, in triplicate, were stimulated with varying concentrations of human recombinant IL-4 (Sigma-Aldrich, Saint Louis, MO). Control groups were treated with media alone. For MUC4 glycoprotein detection, cultures were treated with 2.5 ng/ml of IL-4 for 8 h, washed and re-incubated in fresh medium devoid of IL-4 for an additional 16 h.
Inhibitor studies were carried out by pre-treating cultures separately with 1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio) butadiene (U0126), 2-(1,1-dimethylethyl)-9-fluoro-3,6-dihydro-7H-benz [h]-imidazo [4,5-f]isoquinolin-7-one (DBI) and 4-(4'-hydroxyphenyl) amino-6, 7-dimethoxyquinazoline (WHI-P131) in DMSO at varying concentrations (25–100 μM) for 30 min before exposure to IL-4.
The presence of IL-4 receptor α chain (part of IL-4R) on the cell surface was established by using a rabbit polyclonal anti-human IL-4Rα antibody (Santa Cruz Biotechnology Inc, Santa Cruz, CA). The harvested cells were initially washed with phosphate buffered saline (PBS) solution, fixed in 4% paraformaldehyde for 5 min and permeabilized in 0.1% Triton X-100. Blocking was performed with 4% BSA for 45 min before incubating with primary anti-human IL-4R α Ab at 1:100 dilutions for 1 h. Secondary incubations were performed with Alexa Fluor® (568 nm) labeled mouse anti-rabbit Ab (Molecular Probes, Eugene, OR) at 1:250 for 10 min. The cells were counterstained with DAPI (Molecular Probes; 0.2 μg/ml in PBS) for 2 min before visualizing on a Zeiss Axioplan 2 microscope. Diluent lacking primary Ab and non-immune rabbit IgG were used as controls.
RNA extraction and reverse transcription
Total RNA was extracted by RNeasy Mini kit (Qiagen, Valencia, CA) following the manufacture's protocol. The DNase digestion of the RNA samples was performed on RNeasy columns using the RNAse-free DNase set supplied by the same manufacturer. The integrity of the eluted RNA was confirmed by electrophoresing 5 μl of total RNA on 1.2% agarose/formaldehyde gels. The isolated RNA was reverse transcribed using random hexamers and Superscript II First Strand Synthesis kit (Invitrogen, Carlsbad, CA) following the manufacturer's protocol.
Real-time PCR analysis
Sequence of primers and probes used for Real-time PCR analysis.
Eukaryotic 18S rRNA Endogenous Controls, Applied Biosystems (Foster City, CA)
Nuclear run-on transcription assay
The modified assay involving PCR was adopted from earlier published literature by Rolfe, et al. [31, 32]. Nuclei were extracted from control and IL-4 treated cells after 4 and 8 h using the Nuclei Ez Prep isolation kit (Sigma-Aldrich, Saint Louis, MO). An additional, lyse/wash was included in the protocol to improve the yields of nuclei. Isolated nuclei were layered onto a sucrose cushion (2.1 M sucrose, 5 mM MgAc2, 1 mM EDTA, 10 mM Tris-HCl, pH 8, 1 mM EGTA, 1 mM spermidine, 1 mM dithiothreitol and 0.1 mM phenylmethylsulphonyl fluoride) by centrifugation for 40 min at 16000 × g. Nuclei from treated and control cells were split into two aliquots. One aliquot (+NTP) was incubated for 45 min at 37°C in a solution containing 20 % glycerol, 30 mM Tris-HCl, pH 8, 150 mM KCl, 2.5 mM MgCl2, 1 mM dithiothreitol and 50 U of RNAse OUT® (InVitrogen, Carlsbad, CA) and ATP, CTP, GTP and UTP at 0.5 mM concentration each. The other aliquot (-NTP) was incubated in the same solution without nucleotides. After incubations, RNA was extracted, reverse transcribed and analyzed by real-time PCR as described above.
Plasma membrane protein extraction
Confluent cultures in triplicate were treated with 2.5 ng/ml of IL-4 or control vehicle alone. The cells were initially washed with ice cold PBS solution and recovered by centrifugation at 600 × g for 5 min. Plasma membrane proteins were isolated and purified by Plasma Membrane Protein Extraction Kit (BioVision, Mountain View, CA), following the manufacturers protocol. Protein content of the purified samples was quantified by BCA assay kit (Pierce biotech, Rockford, IL) using BSA as a standard.
Equal amounts of protein (50 μg) were resolved separately on 4–20% SDS polyacrylamide gradient gels and transferred to nitrocellulose membranes. The membranes were then blocked by 5% dry milk in Tris-buffered saline (20 mM Tris-HCl, pH 7.2, 150 mM NaCl) for 2 h at room temperature and then incubated with 1:200 diluted human MUC4-specific 1G8 monoclonal antibody (Zymed labs, San Franciso, CA) for 1 h. Secondary antibody incubations were performed with 1:3000 dilution of horseradish peroxidase-conjugated goat anti-mouse IgG antibody. After three successive washes in TTBS (0.5% Tween-20 in Tris-buffered saline), the membranes were treated with HighSignal West Pico chemiluminescent substrate (Pierce biotech, Rockford, IL) and exposed to BioMax films (Eastman Kodak Co, Rochester, NY) for 1 min. Coomassie blue staining of gels was performed to check for variations in sample loading.
For signal transduction experiments, confluent cultures treated with IL-4 for 0, 5, 10, 15 and 20 min were lysed by sonication on ice in lysis buffer (50 mM Tris-HCl, 150 mM NaCl, 1 mM EDTA, 1 mM PMSF, 1% Triton X-100, 0.1% SDS, 1% sodium deoxycholate, 5 μg/ml Aprotinin, 5 μg/ml Leupeptin). Equal amounts of cell lysates (50 μg) were resolved on gels, transferred to membranes and blocked as stated above. Blotting experiments were performed by incubating the membranes overnight in 1:1000 dilutions of human phosphor-STAT-6 mouse monoclonal antibody and human total STAT-6 rabbit polyclonal antibody (Cell Signaling Technology, Beverly, MA). Secondary antibody incubations were performed for 1 h using 1:10000 dilutions of Alexa Fluor 488 goat anti-mouse and Alexa Fluor 532 goat anti-rabbit IgG antibodies (Molecular Probes, Carlsbad, CA). Membranes were washed thrice and scanned using Molecular Imager FX system (Bio-Rad, Hercules, CA) at 488 nm and 532 nm. After Imaging, the blots were stripped and reprobed using human β-actin monoclonal mouse primary antibody (Sigma-Aldrich, Saint Louis, MO) at 1:5000 dilutions.
Signaling pathway analysis
To understand the signaling mechanism associated with IL-4-mediated MUC4 expression, confluent cultures were treated with MAPK-selective inhibitor, U0126, a pan-JAK inhibitor DBI and a JAK3-selective inhibitor, WHI-P131, at 25, 50 and 100 μM concentrations for 30 min. Following inhibitor treatments, the cells were incubated with 2.5 ng/ml of IL-4 for 2 h. Control cultures were treated with DMSO with or without IL-4. After incubations, total RNA was isolated reverse transcribed and analyzed by real-time PCR as described earlier.
The evaluation of mediator/inhibitor -influenced cytotoxicity was performed in the above experiments by quantifying the lactate dehydrogenase (LDH) content, using the Cytotoxicity Detection Kit (Roche Diagnostics Corporation, Indianapolis, IN).
Data obtained from all the experiments was analyzed by Kruskal-Wallis one-way non-parametric analysis of variance with post hoc evaluations by Mann-Whitney's rank sum test (SAS Institute, Cary, NC). A level of significance was considered at p < 0.05.
IL-4Rα expression in NCI-H650 cells
Localization of IL-4R protein to the cell surface of NCI-H650 cells was established by immunohistochemistry. IL-4R staining was observed on NCI-H650 cell surface using rabbit polyclonal anti-human IL-4Rα antibody but was absent in cells incubated with non-immune rabbit IgG (Fig. 1b, 1c).
Induction of MUC4 expression by IL-4
Transcriptional regulation of MUC4 by IL-4
MUC4 protein expression
Effects of signaling inhibitors
Airway-epithelial cell lines such as A549, Calu-3, HM3, HT29-MTX and H292 have been used as in-vitro model systems for MUC gene expression studies involving a variety of inflammatory mediators [25, 34–37], air pollutants  and bacterial endotoxins [39, 40]. In an earlier study, a similar cell line, NCI-H650, was demonstrated to secrete mucins in culture conditions by a variety of secretagogues, such as 8-bromocyclic AMP, neutrophil elastase and ionomycin, using a polyclonal antibody to normal human tracheobronchial mucin (HTM-1) . Utilizing the same cell line in the present study, we demonstrated the potential role of IL-4 on membrane bound mucin MUC4 regulation in human airways.
The biological actions of IL-4 are initiated by binding to its receptors expressed in varied cell types. Human IL-4R occurs naturally as a membrane bound form and a smaller soluble isoform in airways of asthmatics. The soluble IL-4R lacks the trans-membrane and cytoplasmic domains consistent with the larger membrane bound receptor. Due to the absence of cytoplasmic domains, the soluble receptor upon binding to IL-4 does not induce down-stream signaling cascades [41, 42]. In this study, the presence of IL-4R transcripts in NCI-H650 cells was initially determined by RT-PCR experiments. Localization of IL-4R to NCI-H650 cell surface was established by immunohistochemical studies using a rabbit polyclonal antibody specific to the C-terminal cytoplasmic domain of human membrane bound IL-4Rα. Earlier, the presence of membrane bound IL-4R was demonstrated in airway epithelial cells and cell lines .
Interestingly, IL-4Rα subunit forms part of the signaling complex for IL-4 and IL-13 receptors . In addition, both IL-4 and IL-13 genes have been reported to be increased 18 h after allergen exposure in patients with allergic asthma . Intranasal instillation of IL-4 or IL-13 in mice developed airway esonophilia and AHR, with no such symptoms in transgenic mice lacking IL-4Rα in airways, further emphasizing the role of IL-4Rα in development of asthmatic phenotype . While emphasizing the critical role of IL-13 in asthma, this study explored the relevance of IL-4 in regulation a membrane bound mucin, MUC4.
Exposure of NCI-H650 cells to IL-4 increased steady state MUC4 mRNA in a concentration and time dependent manner, reaching peak expression levels at 2.5 ng/ml and 8 h. Further increasing, the concentration or times of exposure reduced MUC4 levels. This phenomenon could be due to release of Suppression of Cytokine Signaling (SOCS) factors that regulate IL-4 mediated gene expression by negative feed back inhibition [46, 47]. These results are largely confirmatory of studies where IL-4 was shown to up-regulate MUC genes in-vitro  and in-vivo . Our findings stand in contrast to reports where IL-4 down-regulated mucin secretion and up-regulated 15-lipoxygenase enzyme expression (15-LO) in airway epithelial cells . The 15-LO class of dioxygenases enzymes preferentially metabolize exogenous arachidonic acid and linoleic acid to 15-hydroxyeicosatetraenoic acid (15(S)-HETE) and 13-hydroxyoctadecadienoic acid (13-HODE) . The effects of 15-LO metabolites on mucin production are unclear and conflicting reports exist on their ability to regulate mucin production [49, 51, 52]. Nevertheless, the influence of these mediators in this study would be minimal as we detected an increase in MUC4 mRNA levels within 2 h of IL-4 exposure. Our findings reveal a direct effect of IL-4 upon MUC4 gene expression in vitro and are based on quantitative PCR methodology.
In this study, transcriptional up-regulation of MUC4 was established by nuclear run-on experiments. Our findings are in accordance with previous studies where, transcriptional enhancement of airway MUC genes 2 and 5AC was demonstrated in response to cytokines, IL-1β  and IL-9  respectively, in airway epithelial cells. Conversely, our results differ from reports involving neutrophil elastase (NE), which increased MUC5AC and MUC4 levels by post-transcriptional mRNA stabilization [37, 55]. Interestingly, NE treatment of A549 enhanced MUC1 expression at transcriptional level . These reports indicate the regulatory pattern to be both, gene and mediator specific.
Western analysis using a 1G8 monoclonal antibody specific to ASGP-2, a N-glycosylated transmembrane unit of MUC4β, revealed a 140 kDa band in the plasma protein fraction isolated from IL-4-treated NCI-H650 cells. The band obtained was consistent with studies determining MUC4 expression in human corneal epithelium , endothelial cells  and normal human bronchial epithelial (NHBE) cells following NE exposure .
The IL-4 – IL-4R interaction can potentate either JAK or MAPK signaling cascades and consequently, activate STAT-6. Upon activation, STAT-6 dimerizes, translocates to the nucleus, and binds to specific promoter regions to regulate gene transcription [59, 60]. With this knowledge, we investigated the potential effects of a pan-JAK inhibitor, DBI, a JAK3-selective inhibitor, WHI-P131, and a MAPK inhibitor, U0126, upon IL-4-mediated MUC4 expression. DBI is a potent inhibitor of all members of the JAK family and has been reported to block JAK/STAT-dependent proliferation of CTLL cells following IL-4 stimulus . Alternatively, WHI-P131 is a JAK3-selective inhibitor with no effects on JAK1, JAK2, Syk or Src kinases. WHI-P131 was identified as an anti-thrombotic agent that inhibits JAK3 pathway-dependent platelet aggregation . U0126 is a selective inhibitor of MEK1 and MEK2 with little effect on other kinases such as ERK, PKC, JNK and MEKK. U0126 acts as an immunosuppressant by modulating MAPK dependent IL-2 mRNA levels and blocking T-cell proliferation following antigenic stimulus .
In this study, DBI pre-treatments markedly decreased MUC4 expression in IL-4 treated cells, however, no change in expression levels were detected between pre-treatments at 25 and 100 μM concentrations. Replication of the experiments with WHI-P131 at 25, 50 (data not shown) and 100 μM concentrations down-regulated IL-4 mediated MUC4 mRNA in a dose dependent fashion. No change in expression levels were detected upon U0126 pre-treatment at varying concentrations with respect to cells treated with IL-4 alone. While, acknowledging the possibility of parallel activation of JAK1 and JAK3 pathways by IL-4, this study explored the significance of JAK3 signaling cascade on MUC4 gene expression. Our results are supportive of earlier reports where JAK3 preferential tyrosine phosphorylation has been reported in response to cytokines that share the common IL-2 receptor γ-chain such as IL-4, IL-7, and IL-9 [64–66]. On the other hand, our results contradict reports where IL-4 treatment has been shown to elevate MUC2 levels by a MAPK pathway in human colon cancer cells . These contradictions could, in part be explained by reports, which demonstrated IL-4- dependent MAPK signaling to vary with cell types .
Activation of STAT-6 was detected in IL-4 stimulated NCI-H650 cells by western blotting using an antiphospho-STAT-6 antibody. The p-STAT-6 band was evident on resolving lysates from cells incubated with 2.5 ng/ml of IL-4 for 2.5 to 15 min. These findings implicate JAK-mediated STAT-6 activation during IL-4-dependent MUC4 enhancement. Our findings are in accordance with studies where another Th2 cytokine IL-9, was reported to activate MUC5AC via the JAK/STAT pathway .
The molecular mechanisms of MUC4 expression have just begun to be elucidated. Recent reports have shown that interferon-γ (IFN-γ) stimulus up-regulates MUC4 through enhanced STAT-1 expression in human pancreatic tumor cell line CD18/HPAF. In a similar study, retinoic acid (RA) treatment of the same cells enhanced MUC4 expression through TGF-β2-mediated STAT-1 activation . Simultaneous treatments with RA and IFN-γ showed synergistic induction of MUC4 mRNA. Yet, treatment with RA in this study revealed an inhibition of IFN-γ influenced STAT-1 increase; and exposure to IFN-γ subdued RA influenced TGF-β2 induction. Consequently, the possibility of enhanced MUC4 expression through alternate signaling routes during synergistic interaction, distinct from those adopted by their constitutive individual mediators has been hypothesized . In CAPAN-1 and CAPAN-2 cell lines, MUC4 promoter activation was influenced by epidermal growth factor (EGF) or transforming growth factor (TGF)-α through a protein kinase C (PKC) cascade . In human esophageal cell line OE33, bile salts transcriptionally regulated MUC4 expression via phosphatidylinositol 3-kinase pathway (PI3K) .
To date, overall utility of MUC4 to human lung function is unclear; yet, its early expression in human fetal development [71–74] and its specific and timely expression in end-differentiated cell types in adults indicate its potential role in cytodifferentiation [75, 76]. Recent studies have identified Muc4 (rat homologue of human MUC4) as a ligand for ErbB2 receptor. The binding of Muc4 to ErbB2 receptor alone or to neuregulin activated ErbB3-ErbB2 heterodimeric complex regulates the expression of p27kip1, a cyclin dependent kinase inhibitor. The formation of Muc4-ErbB2 complex up-regulates p27kip1 and promotes cell differentiation, in contrast, Muc4-ErbB2-ErbB3-neuregulin complex formation represses p27kip1 and activates Akt pathways leading to cell proliferation . Further, the ability of SMC/Muc4 to alter ErbB2 localization in polarized human colon carcinoma CACO-2 cells has been demonstrated, indicating a strong physical association between the two molecules . In an elegant study, ErbB2 activation was ascertained for epithelial cell repair following NE exposure . In a similar study, NE treatment significantly enhanced MUC4 (the ligand for ErbB2) in bronchial epithelia cells in-vitro . NE is one among a variety of immune cell derived mediators, which modulate airway inflammation and epithelial tissue destruction in chronic respiratory ailments such as CF and asthma.
Numerous studies have hinted at elevated IL-4 expression in bronchoalveolar lavage , breath condensate  and serum  of asthmatics. Further, evaluation of airway biopsies from asthmatic patients has hinted at low, yet increased MUC4 protein levels over normal healthy controls . While acknowledging the important roles of other Th2 cytokines such as IL-5 and IL-13 in regulating MUC genes in asthmatic airways, this study explored the relevance of IL-4 upon a membrane bound mucin MUC4 via the common IL-4Rα chain. Our studies revealed that IL-4 induces MUC4 gene and protein levels. The enhancement was determined primarily to be at the transcriptional stage. In addition, inhibitor studies revealed that IL-4 modulates MUC4 expression by JAK3 selective-STAT-6 pathway.
This study was supported by National Institute of Health grant HL34012. The authors thank Dr. S. Terence Dunn, Department of Pathology and Dr. Randle Gallucci, Department of Pharmaceutical Sciences, OUHSC for critical review of this manuscript.
- Kay AB: Asthma and inflammation. J Allergy Clin Immunol 1991, 87:893–910.View ArticlePubMedGoogle Scholar
- Fahy JV: Remodeling of the airway epithelium in asthma. Am J Respir Crit Care Med 2001, 164:S46–51.View ArticlePubMedGoogle Scholar
- Laitinen LA, Heino M, Laitinen A, Kava T, Haahtela T: Damage of the airway epithelium and bronchial reactivity in patients with asthma. Am Rev Respir Dis 1985, 131:599–606.PubMedGoogle Scholar
- Frew AJ, Moqbel R, Azzawi M, Hartnell A, Barkans J, Jeffery PK, Kay AB, Scheper RJ, Varley J, Church MK, et al.: T lymphocytes and eosinophils in allergen-induced late-phase asthmatic reactions in the guinea pig. Am Rev Respir Dis 1990, 141:407–413.View ArticlePubMedGoogle Scholar
- Azzawi M, Bradley B, Jeffery PK, Frew AJ, Wardlaw AJ, Knowles G, Assoufi B, Collins JV, Durham S, Kay AB: Identification of activated T lymphocytes and eosinophils in bronchial biopsies in stable atopic asthma. Am Rev Respir Dis 1990, 142:1407–1413.View ArticlePubMedGoogle Scholar
- Li D, Wang D, Griffiths-Johnson DA, Wells TN, Williams TJ, Jose PJ, Jeffery PK: Eotaxin protein and gene expression in guinea-pig lungs: constitutive expression and upregulation after allergen challenge. Eur Respir J 1997, 10:1946–1954.View ArticlePubMedGoogle Scholar
- Lukacs NW, Strieter RM, Warmington K, Lincoln P, Chensue SW, Kunkel SL: Differential recruitment of leukocyte populations and alteration of airway hyperreactivity by C-C family chemokines in allergic airway inflammation. J Immunol 1997, 158:4398–4404.PubMedGoogle Scholar
- Fujisawa T, Abu-Ghazaleh R, Kita H, Sanderson CJ, Gleich GJ: Regulatory effect of cytokines on eosinophil degranulation. J Immunol 1990, 144:642–646.PubMedGoogle Scholar
- Renauld JC: New insights into the role of cytokines in asthma. J Clin Pathol 2001, 54:577–589.View ArticlePubMedPubMed CentralGoogle Scholar
- Gonzalo JA, Lloyd CM, Kremer L, Finger E, Martinez AC, Siegelman MH, Cybulsky M, Gutierrez-Ramos JC: Eosinophil recruitment to the lung in a murine model of allergic inflammation. The role of T cells, chemokines, and adhesion receptors. J Clin Invest 1996, 98:2332–2345.View ArticlePubMedPubMed CentralGoogle Scholar
- Kim JS, McKinnis VS, Nawrocki A, White SR: Stimulation of migration and wound repair of guinea-pig airway epithelial cells in response to epidermal growth factor. Am J Respir Cell Mol Biol 1998, 18:66–74.View ArticlePubMedGoogle Scholar
- Davies DE, Polosa R, Puddicombe SM, Richter A, Holgate ST: The epidermal growth factor receptor and its ligand family: their potential role in repair and remodelling in asthma. Allergy 1999, 54:771–783.PubMedGoogle Scholar
- Holbro T, Hynes NE: ErbB receptors: directing key signaling networks throughout life. Annu Rev Pharmacol Toxicol 2004, 44:195–217.View ArticlePubMedGoogle Scholar
- Carraway KL, Rossi EA, Komatsu M, Price-Schiavi SA, Huang D, Guy PM, Carvajal ME, Fregien N, Carraway CA, Carraway KL: An intramembrane modulator of the ErbB2 receptor tyrosine kinase that potentiates neuregulin signaling. J Biol Chem 1999, 274:5263–5266.View ArticlePubMedGoogle Scholar
- Buisine MP, Devisme L, Copin MC, Durand-Reville M, Gosselin B, Aubert JP, Porchet N: Developmental mucin gene expression in the human respiratory tract. Am J Respir Cell Mol Biol 1999, 20:209–218.View ArticlePubMedGoogle Scholar
- Audie JP, Tetaert D, Pigny P, Buisine MP, Janin A, Aubert JP, Porchet N, Boersma A: Mucin gene expression in the human endocervix. Hum Reprod 1995, 10:98–102.View ArticlePubMedGoogle Scholar
- Audie JP, Janin A, Porchet N, Copin MC, Gosselin B, Aubert JP: Expression of human mucin genes in respiratory, digestive, and reproductive tracts ascertained by in situ hybridization. J Histochem Cytochem 1993, 41:1479–1485.View ArticlePubMedGoogle Scholar
- Moniaux N, Nollet S, Porchet N, Degand P, Laine A, Aubert JP: Complete sequence of the human mucin MUC4: a putative cell membrane-associated mucin. Biochem J 1999, 338 ( Pt 2):325–333.View ArticleGoogle Scholar
- Carraway KL, Perez A, Idris N, Jepson S, Arango M, Komatsu M, Haq B, Price-Schiavi SA, Zhang J, Carraway CA: Muc4/sialomucin complex, the intramembrane ErbB2 ligand, in cancer and epithelia: to protect and to survive. Prog Nucleic Acid Res Mol Biol 2002, 71:149–185.View ArticlePubMedGoogle Scholar
- Carraway KL, Ramsauer VP, Haq B, Carothers Carraway CA: Cell signaling through membrane mucins. Bioessays 2003, 25:66–71.View ArticlePubMedGoogle Scholar
- Moniaux N, Varshney GC, Chauhan SC, Copin MC, Jain M, Wittel UA, Andrianifahanana M, Aubert JP, Batra SK: Generation and characterization of anti-MUC4 monoclonal antibodies reactive with normal and cancer cells in humans. J Histochem Cytochem 2004, 52:253–261.View ArticlePubMedGoogle Scholar
- Venkayya R, Lam M, Willkom M, Grunig G, Corry DB, Erle DJ: The Th2 lymphocyte products IL-4 and IL-13 rapidly induce airway hyperresponsiveness through direct effects on resident airway cells. Am J Respir Cell Mol Biol 2002, 26:202–208.View ArticlePubMedGoogle Scholar
- Rankin JA, Picarella DE, Geba GP, Temann UA, Prasad B, DiCosmo B, Tarallo A, Stripp B, Whitsett J, Flavell RA: Phenotypic and physiologic characterization of transgenic mice expressing interleukin 4 in the lung: lymphocytic and eosinophilic inflammation without airway hyperreactivity. Proc Natl Acad Sci U S A 1996, 93:7821–7825.View ArticlePubMedPubMed CentralGoogle Scholar
- Kuperman D, Schofield B, Wills-Karp M, Grusby MJ: Signal transducer and activator of transcription factor 6 (Stat6)-deficient mice are protected from antigen-induced airway hyperresponsiveness and mucus production. J Exp Med 1998, 187:939–948.View ArticlePubMedPubMed CentralGoogle Scholar
- Dabbagh K, Takeyama K, Lee HM, Ueki IF, Lausier JA, Nadel JA: IL-4 induces mucin gene expression and goblet cell metaplasia in vitro and in vivo. J Immunol 1999, 162:6233–6237.PubMedGoogle Scholar
- Seong JK, Koo JS, Lee WJ, Kim HN, Park JY, Song KS, Hong JH, Yoon JH: Upregulation of MUC8 and downregulation of MUC5AC by inflammatory mediators in human nasal polyps and cultured nasal epithelium. Acta Otolaryngol 2002, 122:401–407.View ArticlePubMedGoogle Scholar
- Louahed J, Toda M, Jen J, Hamid Q, Renauld JC, Levitt RC, Nicolaides NC: Interleukin-9 upregulates mucus expression in the airways. Am J Respir Cell Mol Biol 2000, 22:649–656.View ArticlePubMedGoogle Scholar
- Kim CH, Song KS, Koo JS, Kim HU, Cho JY, Kim HJ, Yoon JH: IL-13 suppresses MUC5AC gene expression and mucin secretion in nasal epithelial cells. Acta Otolaryngol 2002, 122:638–643.View ArticlePubMedGoogle Scholar
- Sharma PM, Sarkar MG, Virmani AK, Gazdar AF, Sachdev GP: Evidence of mucin secretion in human lung adenocarcinoma cell lines NCIH650 and NCIH2077 and effect of select secretagogues on mucin secretion. Biosci Rep 1999, 19:473–483.View ArticlePubMedGoogle Scholar
- Argueso P, Balaram M, Spurr-Michaud S, Keutmann HT, Dana MR, Gipson IK: Decreased levels of the goblet cell mucin MUC5AC in tears of patients with Sjogren syndrome. Invest Ophthalmol Vis Sci 2002, 43:1004–1011.PubMedGoogle Scholar
- Rolfe FG, Valentine JE, Sewell WA: Cyclosporin A and FK506 reduce interleukin-5 mRNA abundance by inhibiting gene transcription. Am J Respir Cell Mol Biol 1997, 17:243–250.View ArticlePubMedGoogle Scholar
- Rolfe FG, Sewell WA: Analysis of human interleukin-5 gene transcription by a novel nuclear run on method based on the polymerase chain reaction. J Immunol Methods 1997, 202:143–151.View ArticlePubMedGoogle Scholar
- Doucet C, Brouty-Boye D, Pottin-Clemenceau C, Canonica GW, Jasmin C, Azzarone B: Interleukin (IL) 4 and IL-13 act on human lung fibroblasts. Implication in asthma. J Clin Invest 1998, 101:2129–2139.View ArticlePubMedPubMed CentralGoogle Scholar
- Kim YD, Kwon EJ, Park DW, Song SY, Yoon SK, Baek SH: Interleukin-1beta induces MUC2 and MUC5AC synthesis through cyclooxygenase-2 in NCI-H292 cells. Mol Pharmacol 2002, 62:1112–1118.View ArticlePubMedGoogle Scholar
- Rose MC, Piazza FM, Chen YA, Alimam MZ, Bautista MV, Letwin N, Rajput B: Model systems for investigating mucin gene expression in airway diseases. J Aerosol Med 2000, 13:245–261.View ArticlePubMedGoogle Scholar
- Smirnova MG, Kiselev SL, Birchall JP, Pearson JP: Up-regulation of mucin secretion in HT29-MTX cells by the pro-inflammatory cytokines tumor necrosis factor-alpha and interleukin-6. Eur Cytokine Netw 2001, 12:119–125.PubMedGoogle Scholar
- Voynow JA, Young LR, Wang Y, Horger T, Rose MC, Fischer BM: Neutrophil elastase increases MUC5AC mRNA and protein expression in respiratory epithelial cells. Am J Physiol 1999, 276:L835–43.PubMedGoogle Scholar
- Borchers MT, Carty MP, Leikauf GD: Regulation of human airway mucins by acrolein and inflammatory mediators. Am J Physiol 1999, 276:L549–55.PubMedGoogle Scholar
- Li JD, Dohrman AF, Gallup M, Miyata S, Gum JR, Kim YS, Nadel JA, Prince A, Basbaum CB: Transcriptional activation of mucin by Pseudomonas aeruginosa lipopolysaccharide in the pathogenesis of cystic fibrosis lung disease. Proc Natl Acad Sci U S A 1997, 94:967–972.View ArticlePubMedPubMed CentralGoogle Scholar
- Li JD, Feng W, Gallup M, Kim JH, Gum J, Kim Y, Basbaum C: Activation of NF-kappaB via a Src-dependent Ras-MAPK-pp90rsk pathway is required for Pseudomonas aeruginosa-induced mucin overproduction in epithelial cells. Proc Natl Acad Sci U S A 1998, 95:5718–5723.View ArticlePubMedPubMed CentralGoogle Scholar
- Steinke JW, Borish L: Th2 cytokines and asthma. Interleukin-4: its role in the pathogenesis of asthma, and targeting it for asthma treatment with interleukin-4 receptor antagonists. Respir Res 2001, 2:66–70.View ArticlePubMedPubMed CentralGoogle Scholar
- Henderson WRJ, Chi EY, Maliszewski CR: Soluble IL-4 receptor inhibits airway inflammation following allergen challenge in a mouse model of asthma. J Immunol 2000, 164:1086–1095.View ArticlePubMedGoogle Scholar
- Callard RE, Matthews DJ, Hibbert L: IL-4 and IL-13 receptors: are they one and the same? Immunol Today 1996, 17:108–110.View ArticlePubMedGoogle Scholar
- Kroegel C, Julius P, Matthys H, Virchow JCJ, Luttmann W: Endobronchial secretion of interleukin-13 following local allergen challenge in atopic asthma: relationship to interleukin-4 and eosinophil counts. Eur Respir J 1996, 9:899–904.View ArticlePubMedGoogle Scholar
- Wills-Karp M, Luyimbazi J, Xu X, Schofield B, Neben TY, Karp CL, Donaldson DD: Interleukin-13: central mediator of allergic asthma. Science 1998, 282:2258–2261.View ArticlePubMedGoogle Scholar
- Seki Y, Hayashi K, Matsumoto A, Seki N, Tsukada J, Ransom J, Naka T, Kishimoto T, Yoshimura A, Kubo M: Expression of the suppressor of cytokine signaling-5 (SOCS5) negatively regulates IL-4-dependent STAT6 activation and Th2 differentiation. Proc Natl Acad Sci U S A 2002, 99:13003–13008.View ArticlePubMedPubMed CentralGoogle Scholar
- Yasukawa H, Sasaki A, Yoshimura A: Negative regulation of cytokine signaling pathways. Annu Rev Immunol 2000, 18:143–164.View ArticlePubMedGoogle Scholar
- Temann UA, Prasad B, Gallup MW, Basbaum C, Ho SB, Flavell RA, Rankin JA: A novel role for murine IL-4 in vivo: induction of MUC5AC gene expression and mucin hypersecretion. Am J Respir Cell Mol Biol 1997, 16:471–478.View ArticlePubMedGoogle Scholar
- Jayawickreme SP, Gray T, Nettesheim P, Eling T: Regulation of 15-lipoxygenase expression and mucus secretion by IL-4 in human bronchial epithelial cells. Am J Physiol 1999, 276:L596–603.PubMedGoogle Scholar
- Chanez P, Bonnans C, Chavis C, Vachier I: 15-lipoxygenase: a Janus enzyme? Am J Respir Cell Mol Biol 2002, 27:655–658.View ArticlePubMedGoogle Scholar
- Adler KB, Akley NJ, Glasgow WC: Platelet-activating factor provokes release of mucin-like glycoproteins from guinea pig respiratory epithelial cells via a lipoxygenase-dependent mechanism. Am J Respir Cell Mol Biol 1992, 6:550–556.View ArticlePubMedGoogle Scholar
- Marom Z, Shelhamer JH, Sun F, Kaliner M: Human airway monohydroxyeicosatetraenoic acid generation and mucus release. J Clin Invest 1983, 72:122–127.View ArticlePubMedPubMed CentralGoogle Scholar
- Kim YD, Kwon EJ, Kwon TK, Baek SH, Song SY, Suh JS: Regulation of IL-1beta-mediated MUC2 gene in NCI-H292 human airway epithelial cells. Biochem Biophys Res Commun 2000, 274:112–116.View ArticlePubMedGoogle Scholar
- Longphre M, Li D, Gallup M, Drori E, Ordonez CL, Redman T, Wenzel S, Bice DE, Fahy JV, Basbaum C: Allergen-induced IL-9 directly stimulates mucin transcription in respiratory epithelial cells. J Clin Invest 1999, 104:1375–1382.View ArticlePubMedPubMed CentralGoogle Scholar
- Fischer BM, Cuellar JG, Diehl ML, deFreytas AM, Zhang J, Carraway KL, Voynow JA: Neutrophil elastase increases MUC4 expression in normal human bronchial epithelial cells. Am J Physiol Lung Cell Mol Physiol 2003, 284:L671–9.View ArticlePubMedGoogle Scholar
- Kuwahara I, Lillehoj EP, Hisatsune A, Lu W, Isohama Y, Miyata T, Kim KC: Neutrophil elastase stimulates MUC1 gene expression through increased Sp1 binding to the MUC1 promoter. Am J Physiol Lung Cell Mol Physiol 2005, 289:L355–62.View ArticlePubMedGoogle Scholar
- Pflugfelder SC, Liu Z, Monroy D, Li DQ, Carvajal ME, Price-Schiavi SA, Idris N, Solomon A, Perez A, Carraway KL: Detection of sialomucin complex (MUC4) in human ocular surface epithelium and tear fluid. Invest Ophthalmol Vis Sci 2000, 41:1316–1326.PubMedGoogle Scholar
- Zhang J, Perez A, Yasin M, Soto P, Rong M, Theodoropoulos G, Carothers Carraway CA, Carraway KL: Presence of MUC4 in human milk and at the luminal surfaces of blood vessels. J Cell Physiol 2005, 204:166–177.View ArticlePubMedGoogle Scholar
- Shuai K, Liu B: Regulation of JAK-STAT signalling in the immune system. Nat Rev Immunol 2003, 3:900–911.View ArticlePubMedGoogle Scholar
- Hunt AE, Williams LM, Lali FV, Foxwell BM: IL-4 regulation of p38 MAPK signalling is dependent on cell type. Cytokine 2002, 18:295–303.View ArticlePubMedGoogle Scholar
- Thompson JE, Cubbon RM, Cummings RT, Wicker LS, Frankshun R, Cunningham BR, Cameron PM, Meinke PT, Liverton N, Weng Y, DeMartino JA: Photochemical preparation of a pyridone containing tetracycle: a Jak protein kinase inhibitor. Bioorg Med Chem Lett 2002, 12:1219–1223.View ArticlePubMedGoogle Scholar
- Tibbles HE, Vassilev A, Wendorf H, Schonhoff D, Zhu D, Lorenz D, Waurzyniak B, Liu XP, Uckun FM: Role of a JAK3-dependent biochemical signaling pathway in platelet activation and aggregation. J Biol Chem 2001, 276:17815–17822.View ArticlePubMedGoogle Scholar
- DeSilva DR, Jones EA, Favata MF, Jaffee BD, Magolda RL, Trzaskos JM, Scherle PA: Inhibition of mitogen-activated protein kinase kinase blocks T cell proliferation but does not induce or prevent anergy. J Immunol 1998, 160:4175–4181.PubMedGoogle Scholar
- Malabarba MG, Kirken RA, Rui H, Koettnitz K, Kawamura M, O'Shea JJ, Kalthoff FS, Farrar WL: Activation of JAK3, but not JAK1, is critical to interleukin-4 (IL4) stimulated proliferation and requires a membrane-proximal region of IL4 receptor alpha. J Biol Chem 1995, 270:9630–9637.View ArticlePubMedGoogle Scholar
- Johnston JA, Kawamura M, Kirken RA, Chen YQ, Blake TB, Shibuya K, Ortaldo JR, McVicar DW, O'Shea JJ: Phosphorylation and activation of the Jak-3 Janus kinase in response to interleukin-2. Nature 1994, 370:151–153.View ArticlePubMedGoogle Scholar
- Witthuhn BA, Silvennoinen O, Miura O, Lai KS, Cwik C, Liu ET, Ihle JN: Involvement of the Jak-3 Janus kinase in signalling by interleukins 2 and 4 in lymphoid and myeloid cells. Nature 1994, 370:153–157.View ArticlePubMedGoogle Scholar
- Iwashita J, Sato Y, Sugaya H, Takahashi N, Sasaki H, Abe T: mRNA of MUC2 is stimulated by IL-4, IL-13 or TNF-alpha through a mitogen-activated protein kinase pathway in human colon cancer cells. Immunol Cell Biol 2003, 81:275–282.View ArticlePubMedGoogle Scholar
- Perrais M, Pigny P, Ducourouble MP, Petitprez D, Porchet N, Aubert JP, Van Seuningen I: Characterization of human mucin gene MUC4 promoter: importance of growth factors and proinflammatory cytokines for its regulation in pancreatic cancer cells. J Biol Chem 2001, 276:30923–30933.View ArticlePubMedGoogle Scholar
- Andrianifahanana M, Agrawal A, Singh AP, Moniaux N, van Seuningen I, Aubert JP, Meza J, Batra SK: Synergistic induction of the MUC4 mucin gene by interferon-gamma and retinoic acid in human pancreatic tumour cells involves a reprogramming of signalling pathways. Oncogene 2005.Google Scholar
- Mariette C, Perrais M, Leteurtre E, Jonckheere N, Hemon B, Pigny P, Batra S, Aubert JP, Triboulet JP, Van Seuningen I: Transcriptional regulation of human mucin MUC4 by bile acids in oesophageal cancer cells is promoter-dependent and involves activation of the phosphatidylinositol 3-kinase signalling pathway. Biochem J 2004, 377:701–708.View ArticlePubMedPubMed CentralGoogle Scholar
- Buisine MP, Devisme L, Degand P, Dieu MC, Gosselin B, Copin MC, Aubert JP, Porchet N: Developmental mucin gene expression in the gastroduodenal tract and accessory digestive glands. II. Duodenum and liver, gallbladder, and pancreas. J Histochem Cytochem 2000, 48:1667–1676.View ArticlePubMedGoogle Scholar
- Buisine MP, Devisme L, Maunoury V, Deschodt E, Gosselin B, Copin MC, Aubert JP, Porchet N: Developmental mucin gene expression in the gastroduodenal tract and accessory digestive glands. I. Stomach. A relationship to gastric carcinoma. J Histochem Cytochem 2000, 48:1657–1666.View ArticlePubMedGoogle Scholar
- Reid CJ, Harris A: Developmental expression of mucin genes in the human gastrointestinal system. Gut 1998, 42:220–226.View ArticlePubMedPubMed CentralGoogle Scholar
- Reid CJ, Gould S, Harris A: Developmental expression of mucin genes in the human respiratory tract. Am J Respir Cell Mol Biol 1997, 17:592–598.View ArticlePubMedGoogle Scholar
- Bernacki SH, Nelson AL, Abdullah L, Sheehan JK, Harris A, Davis CW, Randell SH: Mucin gene expression during differentiation of human airway epithelia in vitro. Muc4 and muc5b are strongly induced. Am J Respir Cell Mol Biol 1999, 20:595–604.View ArticlePubMedGoogle Scholar
- Gray T, Koo JS, Nettesheim P: Regulation of mucous differentiation and mucin gene expression in the tracheobronchial epithelium. Toxicology 2001, 160:35–46.View ArticlePubMedGoogle Scholar
- Weed DT, Gomez-Fernandez C, Yasin M, Hamilton-Nelson K, Rodriguez M, Zhang J, Carraway KL: MUC4 and ErbB2 expression in squamous cell carcinoma of the upper aerodigestive tract: correlation with clinical outcomes. Laryngoscope 2004, 114:1–32.View ArticlePubMedGoogle Scholar
- Ramsauer VP, Carraway CA, Salas PJ, Carraway KL: Muc4/sialomucin complex, the intramembrane ErbB2 ligand, translocates ErbB2 to the apical surface in polarized epithelial cells. J Biol Chem 2003, 278:30142–30147.View ArticlePubMedGoogle Scholar
- Fischer BM, Cuellar JG, Byrd AS, Rice AB, Bonner JC, Martin LD, Voynow JA: ErbB2 activity is required for airway epithelial repair following neutrophil elastase exposure. Faseb J 2005, 19:1374–1376.View ArticlePubMedGoogle Scholar
- Walker C, Bauer W, Braun RK, Menz G, Braun P, Schwarz F, Hansel TT, Villiger B: Activated T cells and cytokines in bronchoalveolar lavages from patients with various lung diseases associated with eosinophilia. Am J Respir Crit Care Med 1994, 150:1038–1048.View ArticlePubMedGoogle Scholar
- Shahid SK, Kharitonov SA, Wilson NM, Bush A, Barnes PJ: Increased interleukin-4 and decreased interferon-gamma in exhaled breath condensate of children with asthma. Am J Respir Crit Care Med 2002, 165:1290–1293.View ArticlePubMedGoogle Scholar
- Matsumoto T, Miike T, Yamaguchi K, Murakami M, Kawabe T, Yodoi J: Serum levels of soluble IL-2 receptor, IL-4 and IgE-binding factors in childhood allergic diseases. Clin Exp Immunol 1991, 85:288–292.View ArticlePubMedPubMed CentralGoogle Scholar
- Ordonez CL, Khashayar R, Wong HH, Ferrando R, Wu R, Hyde DM, Hotchkiss JA, Zhang Y, Novikov A, Dolganov G, Fahy JV: Mild and moderate asthma is associated with airway goblet cell hyperplasia and abnormalities in mucin gene expression. Am J Respir Crit Care Med 2001, 163:517–523.View ArticlePubMedGoogle Scholar
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