Induction of MUC8 Gene Expression by Interleukin-1β Is Mediated by a Sequential ERK MAPK/RSK1/CREB Cascade Pathway in Human Airway Epithelial Cells

Mucins are the major components of the mucus layer that covers and protects the respiratory, digestive, and reproductive tracts. Our previous studies showed that MUC8 gene expression was overexpressed in in vivo polyp epithelium in chronic sinusitis and was also increased by treatment with inflammatory mediators in an in vitro culture condition. However, the mechanisms by which the inflammatory mediators-induced MUC8 gene expression in normal nasal epithelial cells evolved remain unclear. We examined the mechanism by which the important proinflammatory mediator, interleukin (IL)-1β, increases MUC8 gene expression levels. We found that pharmacologic and genetic inhibition of ERK MAPK pathway abolished IL-1β-induced MUC8 gene expression in normal human nasal epithelial cells. Moreover, the overexpression of wide-type or of the dominant-negative mutant of p90 ribosomal S6 protein kinase 1 (RSK1) enhanced or suppressed, respectively, IL-1β-induced MUC8 gene expression. RSK1 was found to directly phosphorylate cAMP-response element-binding protein (CREB), and this event led to the stimulation of subsequent CRE-mediated gene transcription. In conclusion, IL-1β was found to induce MUC8 gene expression via a sequential ERK/RSK1/CREB pathway in human airway epithelial cells. Mucins are the major components of the mucus layer that covers and protects the respiratory, digestive, and reproductive tracts. Our previous studies showed that MUC8 gene expression was overexpressed in in vivo polyp epithelium in chronic sinusitis and was also increased by treatment with inflammatory mediators in an in vitro culture condition. However, the mechanisms by which the inflammatory mediators-induced MUC8 gene expression in normal nasal epithelial cells evolved remain unclear. We examined the mechanism by which the important proinflammatory mediator, interleukin (IL)-1β, increases MUC8 gene expression levels. We found that pharmacologic and genetic inhibition of ERK MAPK pathway abolished IL-1β-induced MUC8 gene expression in normal human nasal epithelial cells. Moreover, the overexpression of wide-type or of the dominant-negative mutant of p90 ribosomal S6 protein kinase 1 (RSK1) enhanced or suppressed, respectively, IL-1β-induced MUC8 gene expression. RSK1 was found to directly phosphorylate cAMP-response element-binding protein (CREB), and this event led to the stimulation of subsequent CRE-mediated gene transcription. In conclusion, IL-1β was found to induce MUC8 gene expression via a sequential ERK/RSK1/CREB pathway in human airway epithelial cells. Mucins are highly glycosylated, high molecular mass glycoproteins and are major components of the mucus produced by the epithelia of the respiratory, gastrointestinal, and reproductive tracts. They are responsible for the viscoelastic properties of secreted mucus and provide lubrication and protection for mucus membranes (1Gray T. Nettesheim P. Basbaum C. Koo J.S. Biochem. J. 2001; 353: 727-734Crossref PubMed Scopus (16) Google Scholar). In the airway, virtually all forms of airway inflammation are associated with the overproduction of mucus, which can lead to airway obstruction (2Basbaum C. Lemjabbar H. Longphre M. Li D. Gensch E. McNamara N. Am. J. Resp. Crit. Care. Med. 1999; 160: S44-S48Crossref PubMed Scopus (119) Google Scholar). Eighteen types of mucin genes have been discovered to date: MUC1 to MUC4, MUC5AC, MUC5B, MUC6, MUC7, MUC8 (2Basbaum C. Lemjabbar H. Longphre M. Li D. Gensch E. McNamara N. Am. J. Resp. Crit. Care. Med. 1999; 160: S44-S48Crossref PubMed Scopus (119) Google Scholar), MUC9 (3Lapensee L. Paquette Y. Bleau G. Fertil. Steril. 1997; 68: 702-708Abstract Full Text PDF PubMed Scopus (145) Google Scholar), MUC10 (4Melnick M. Chen H. Zhou Y. Jaskoll T. Arch. Oral. Biol. 2001; 46: 745-757Crossref PubMed Scopus (22) Google Scholar), MUC11, MUC12 (5Williams S. McGluckin M. Gotley D. Eyre H. Sutherland G. Antalis T. Cancer Res. 1999; 59: 4083-4089PubMed Google Scholar), MUC13 (6Williams S.J. Wreschner D.H. Tran M. Eyre H.J. Sutherland G.R. McGuckin M.A. J. Biol. Chem. 2001; 276: 18327-18336Abstract Full Text Full Text PDF PubMed Scopus (256) Google Scholar), MUC15 (7Pallesen L.T. Berglund L. Rasmussen L.K. Petersen T.E. Rasmussen J.T. Eur. J. Biochem. 2002; 269: 2755-2763Crossref PubMed Scopus (120) Google Scholar), MUC16 (8Yin B.W. Lloyd K.O. J. Biol. Chem. 2001; 276: 27371-27375Abstract Full Text Full Text PDF PubMed Scopus (494) Google Scholar), MUC17 (9Gum Jr., J.R. Crawley S.C. Hicks J.W. Szymkowski D.E. Kim Y.S. Biochem. Biophys. Res. Commun. 2002; 291: 466-475Crossref PubMed Scopus (168) Google Scholar), and MUC18 (10Sers C. Kirsch K. Rothbacher U. Riethmuller G. Johnson J.P. Proc. Natl. Acad. Sci. U. S. A. 1993; 90: 8514-8518Crossref PubMed Scopus (128) Google Scholar). Of these, MUC5AC and MUC5B are known to be major gel-foaming mucins secreted in the human airway. Accordingly, most studies on mucin genes have been focused on these two mucins. However, although MUC5AC is known to be expressed by most surface goblet cells, we found that only a portion of the goblet cells (11Kim C.H. Song K.S. Kim S.S. Kim H.U. Seong J.K. Yoon J.H. Laryngoscope. 2000; 110: 2110-2113Crossref PubMed Scopus (31) Google Scholar) expressed MUC5AC mRNA. This suggests that other mucin genes in addition to MUC5AC might be important for mucus hypersecretion. We have previously investigated the expressions of other mucin genes using various inflammatory tissues and cell lysates. Interestingly, in vivo, we found that MUC8 mRNA levels are clearly up-regulated in the polyp epithelium, which is invariably stimulated by inflammatory mediators (12Kim S.S. Kim K.S. Lee J.K. Park I.Y. Koo J.S. Yoon J.H. Laryngoscope. 2000; 110: 276-280Crossref PubMed Scopus (44) Google Scholar). In addition, in vitro, interleukin-1β (IL-1β), 1The abbreviations used are: IL-1β, interleukin 1β; MUC, mucin; MAPK, mitogen-activated protein kinase; ERK, extracellular signal-regulated kinase; MEK1, MAPK/ERK kinase 1; SAPK, stress-activated protein kinase; MSK1, mitogen- and stress-activated protein kinase 1; RSK1, p90 ribosomal S6 protein kinase 1; CRE, cAMP-response element; CREB, CRE-binding protein; EMSA, electrophoretic mobility shift analysis; W/T, wide-type; DN, dominant-negative; JNK, c-Jun NH2-terminal kinase; NHNE, normal human nasal epithelial; FBS, fetal bovine serum; PBS, phosphate-buffered saline; FAM, carboxyfluorescein; TAMRA, carboxytetramethylrhodamine; DTT, dithiothreitol; IBMX, isobutylmethylxanthine.1The abbreviations used are: IL-1β, interleukin 1β; MUC, mucin; MAPK, mitogen-activated protein kinase; ERK, extracellular signal-regulated kinase; MEK1, MAPK/ERK kinase 1; SAPK, stress-activated protein kinase; MSK1, mitogen- and stress-activated protein kinase 1; RSK1, p90 ribosomal S6 protein kinase 1; CRE, cAMP-response element; CREB, CRE-binding protein; EMSA, electrophoretic mobility shift analysis; W/T, wide-type; DN, dominant-negative; JNK, c-Jun NH2-terminal kinase; NHNE, normal human nasal epithelial; FBS, fetal bovine serum; PBS, phosphate-buffered saline; FAM, carboxyfluorescein; TAMRA, carboxytetramethylrhodamine; DTT, dithiothreitol; IBMX, isobutylmethylxanthine. tumor necrosis factor-α, and a mixture of inflammatory mediators were found to up-regulate MUC8 mRNA and to down-regulate MUC5AC mRNA (13Yoon J.H. Kim K.S. Kim H.U. Linton J.A. Lee J.G. Acta Otolaryngol. 1999; 119: 905-910Crossref PubMed Scopus (57) Google Scholar, 14Seong J.K. Koo J.S. Lee W.J. Kim H.N. Park J.Y. Song K.S. Hong J.H. Yoon J.H. Acta Otolaryngol. 2002; 122: 401-407Crossref PubMed Scopus (47) Google Scholar). These results showed that MUC8 mRNA is increased both in vivo and in vitro during inflammatory conditions. However, the mechanisms of MUC8 gene expression during inflammation in normal airway epithelial cells and the signal molecules involved have not been elucidated. Mitogen-activated protein kinases (MAPKs) are ubiquitous kinases and are involved in signal transduction in eukaryotic organisms. This family of kinases is characterized by their activation by MAPKs through the dual phosphorylation of Thr and Tyr residues in their activation loop. The MAPK family includes extracellular signal-regulated kinases (ERK), which are activated in response to growth factors, via the Ras protooncogene. Moreover, c-Jun N-terminal kinase (JNK) and p38 MAPK constitute two other families, collectively known as stress-activated protein kinases (SAPK), because they are induced by UV radiation, heat-shock, oxidative stress, or tumor necrosis factor-α. The stimulation of ERK initiates a cascade of activating events, including the phosphorylation of p90 ribosomal S6 protein kinase 1 (RSK1), and its translocation to the nucleus, where RSK1 phosphorylates nuclear substrates (15Richards S.A. Dreisbach V.C. Murphy L.O. Blenis J. Mol. Cell Biol. 2001; 21: 7470-7480Crossref PubMed Scopus (78) Google Scholar). Moreover, the phosphorylation of mitogen- and stress-activated protein kinase (MSK), which localized in the nuclei (16Deak M. Clifton A.D. Lucocq L.M. Alessi D.R. EMBO J. 1998; 17: 4426-4441Crossref PubMed Scopus (844) Google Scholar), could lead to the phosphorylation and activation several transcription factors like cAMP-response element-binding protein (CREB) and activating transcription factor 1 (ATF1) (17Van Seuningen I. Pigny P. Perrais M. Porchet N. Aubert J.P. Front. Biosci. 2001; 6: 1216-1234Crossref PubMed Google Scholar). We examined the mechanism by which the important proinflammatory mediator, IL-1β, increases MUC8 gene expression levels. Here we show that ERK MAPK is essential for IL-1β-induced MUC8 gene expression in normal human nasal epithelial (NHNE) cells. We also show that RSK1 mediates the IL-1β-induced phosphorylation of CREB and CRE-mediated transcription. Molecular cloning of the MUC8 promoter regulated by various stimuli may yield a deeper insight into cellular function. Materials—PD98059, SB203580, and anti-α-tubulin antibody were purchased from Calbiochem (San Diego, CA). Anti-phospho-p44/42 MAPK (Thr202/Tyr204) antibody, anti-phospho-p38 MAPK (Thr180/Tyr182) antibody, anti-phospho-SAPK/JNK MAPK (Thr183/Tyr185) antibody, anti-phospho-RSK1 (Ser380) antibody, and anti-phospho-CREB (Ser133) antibody were purchased from Cell Signaling (Beverly, MA). cDNA construct encoding dominant-negative Raf1 construct was kindly provided by Dr. J. H. Kim (University of Korea, Seoul, Korea). Cell Cultures—The culture system used for the normal human nasal epithelial (NHNE) cells has been previously reported (13Yoon J.H. Kim K.S. Kim H.U. Linton J.A. Lee J.G. Acta Otolaryngol. 1999; 119: 905-910Crossref PubMed Scopus (57) Google Scholar). The human lung mucoepidermoid carcinoma cell line, NCI-H292, was purchased from the American Type Culture Collection (CRL-1848, Manassas, VA) and was cultured in RPMI 1640 (Invitrogen) supplemented with 10% fetal bovine serum (FBS) in the presence of penicillin-streptomycin at 37 °C in a 5% CO2 humidified chamber. For serum deprivation, confluent cells were washed twice with phosphate-buffered saline (PBS) and re-cultured in RPMI 1640 with 0.2% FBS. Real-time Quantitative PCR—Primers and probes were designed using PerkinElmer Life Sciences Primer Express® software, purchased from PE Biosystems. Commercial reagents (TaqMan PCR Universal PCR Master Mix, PE Biosystems) and conditions were applied according to the manufacturer's protocol. One microgram of cDNA (reverse transcription mixture), oligonucleotides at a final concentration of 800 nm of primers, and 200 nm TaqMan hybridization probe were used in a 25-μl volume. The probe of real-time PCR was labeled with carboxyfluorescein (FAM) at the 5′-end and with the quencher carboxytetramethylrhodamine (TAMRA) at the 3′-end. The following primers and TaqMan probes were used: MUC8, forward (5′-GACCTGCCCCCATGGAC-3′) and reverse (5′-CAGGAGTTCGAGACCAGCCT-3′) and TaqMan probe (6FAM-CCACCTCCGAGCCCGTCACTGAG-TAMRA). β 2M, forward (5′-CGCTCCGTGGCCTTAGC-3′) and reverse (5′-GAGTACGCTGGATAGCCTCCA-3′) and TaqMan probe (6FAM-TGCTCGCGCTACTCTCTCTTTCTGGC-TAMRA). Real-time reverse transcription-PCR was performed on a PE Biosystems ABI PRISM® 7700 Sequence Detection System (Foster City, CA). The thermocycler (ABI PRISM® 7700 Sequence Detection System) parameters were 50 °C for 2 min, 95 °C for 10 min, followed by 40 cycles of 95 °C for 15 s and 60 °C for 1 min. All reactions were performed in triplicate. Relative quantity of MUC8 mRNA was obtained using a comparative cycle of threshold method, and results were normalized against β 2M as an endogenous control. Western Blot Analysis—NCI-H292 cells were grown to confluence in 6-well plates. After 15 or 45 min of treatment with IL-1β, the cells were lysed with 2× lysis buffer (250 mm Tris-Cl (pH 6.5), 2% SDS, 4% β-mercaptoethanol, 0.02% 10% of cell were by 10% and to a MA). were with 5% in saline mm Tris-Cl (pH mm for 2 at This was with antibody in in After with the was for 45 min at with or antibody in and using the system of an Cell encoding the mutant was with and with CA). This was with in with with and to CA). encoding p38 mutant was with in with with and to cells were with and or of to expression using following the by the cell were with 200 and the was with and microgram of CREB antibody was at °C with of cell using lysis buffer mm Tris-Cl (pH 1 mm mm 1 1 1 mm 10 mm 1 mm mm 10% 1 mm mm of a of protein was to the cell and for 2 at with The were and washed with cell lysis were by the in and were on In RSK1 serum deprivation, confluent cells were washed twice with and in RPMI 1640 0.2% FBS. were with IL-1β for min, and lysed in lysis of the protein obtained was with anti-phospho-RSK1 (Ser380) antibody at were to 40 of protein were washed in lysis and kinase reactions were for 1 at °C in of kinase buffer mm (pH mm 200 of 10 of and of expressed as a were by buffer and by followed by were washed with and were in nuclear buffer mm (pH 10 mm mm mm DTT, 1 mm 2 and 2 for 15 min on and were in nuclear buffer mm (pH mm 1 mm mm DTT, mm 2 and 2 and The nuclear were for 15 min at and the were at For EMSA, oligonucleotides to the were and with using was at for min with the probe in buffer mm mm mm DTT, mm 50 mm Tris-Cl (pH and protein were from the probe by through 5% in were using 2 of anti-phospho-CREB The was and using an at and construct and mutant CREB with by were using a according to the manufacturer's were for and for using a system according to the manufacturer's was also to the of ERK MAPK on IL-1β-induced MUC8 ERK and p38 MAPKs activation treatment with IL-1β, this at 45 min in cells. was in the activation of K.S. Lee W.J. Koo J.S. J.Y. Yoon J.H. J. Biol. Chem. Scholar). the of ERK or p38 MAPK pathway in IL-1β-induced MUC8 gene we performed real-time PCR with or for 1 Real-time PCR showed that with for 1 MUC8 gene expression However, with not MUC8 gene expression These results that the activation of ERK MAPK, not of p38 MAPK, to be to IL-1β-induced MUC8 gene expression. the was performed using cells, a human lung mucoepidermoid carcinoma cell line, we obtained results that were to of normal cells not the of ERK or p38 kinase the cellular of MUC8 gene we cells dominant-negative mutant or p38 of the After to induce cells were stimulated with IL-1β for 15 min, and IL-1β-induced phosphorylation of ERK However, in ERK expression was Real-time PCR showed a in MUC8 gene expression In a we investigated the of p38 MAPK on IL-1β-induced MUC8 gene expression using in vitro kinase showed that the activation of p38 MAPK in this mutant cell was in the presence of IL-1β However, the IL-1β-induced MUC8 gene expression was not by These results showed that ERK MAPK, not p38 MAPK, was essential for IL-1β-induced MUC8 gene expression in cells. the sequential pathway a in IL-1β-induced MUC8 gene we with encoding or a of The of Ras or Raf1 not the phosphorylation of ERK MAPK and the IL-1β-induced MUC8 gene expression cells were used as a for these dominant-negative E. K. Y. H. J. Cell Sci. 2000; Google Scholar). These results show that the activation of ERK MAPK via by IL-1β might via a pathway to induce MUC8 gene expression in airway epithelial cells. of RSK1 on IL-1β-induced MUC8 which molecules are involved in the of ERK MAPK in IL-1β-induced MUC8 gene we investigated RSK1 and RSK1 has been reported to be activated by ERK MAPK Y. Y. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, Kim Lee Kim Kim J. Biol. Chem. 2001; 276: Full Text Full Text PDF PubMed Scopus Google Scholar, J.H. Am. J. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). The phosphorylation of RSK1 by IL-1β at min and at 60 min IL-1β stimulation with IL-1β-induced RSK1 phosphorylation that RSK1 is regulated by ERK These results showed that RSK1 as a of ERK RSK1 an important in IL-1β-induced MUC8 gene an RSK1 mutant was RSK1 is a for the of CREB phosphorylation at Y. Y. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, J. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, J. Alessi D.R. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). of wide-type RSK1 increased IL-1β-induced CREB However, the overexpression of the IL-1β-induced CREB IL-1β-induced MUC8 gene expression was increased by overexpression of RSK1, the IL-1β-induced MUC8 gene expression was by These results show that RSK1 is for IL-1β-induced MUC8 gene expression. of CREB on IL-1β-induced MUC8 examined RSK1 to CREB in human airway cells. Cell obtained stimulation with IL-1β were with CREB antibody and with an RSK1 in protein was RSK1 and The was used as an In addition, a phosphorylation of CREB was the stimulation with IL-1β, the at min. These results that IL-1β-induced RSK1 to the phosphorylation of CREB in cells. IL-1β-induced is we performed an in vitro kinase using expressed as a in IL-1β-induced RSK1 increased in cells with RSK1, the overexpression of RSK1 IL-1β-induced RSK1 CREB a in MUC8 gene we used both of and an of The phosphorylation of CREB was stimulation with both and IBMX, and this a at 10 min K.S. Lee W.J. Koo J.S. J.Y. Yoon J.H. J. Biol. Chem. Scholar). The CREB phosphorylation increased MUC8 gene expression IL-1β-induced MUC8 gene expression was in cells with encoding These that the activation of CREB is essential for IL-1β-induced MUC8 gene expression via ERK MAPK and CREB CRE-mediated in to the of CREB, we performed using nuclear from cells treatment with IL-1β for 1 in the of increased in response to and were performed using a of and an anti-phospho-CREB antibody, was found to be by the and to be by anti-phospho-CREB These results that activated CREB to a which we to as we the gene expression of the construct to IL-1β a on the activation of CREB and on the subsequent CRE-mediated gene transcription. the of CREB phosphorylation on CRE-mediated gene cells were with only or both and encoding CREB of cells with IL-1β in increased CRE-mediated gene transcription in a The expression of CREB a of the was found to the induced by used as a showed of CRE-mediated transcription. These results that CREB CRE-mediated transcription by to is an important of the airway and through the and these are by mucus and by the mucus during inflammation may a and inflammatory mediators the of epithelial cells to A. Am. J. Med. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar, Eur. J. 1997; PubMed Scopus Google Scholar, J. E. T. A. E. A. M. D. J. 2001; PubMed Scopus Google Scholar). The molecular mechanism by which MUC8 gene expression is up-regulated by IL-1β In the we investigated the mechanisms by which MUC8 gene expression is up-regulated by IL-1β in normal human nasal epithelial cells. Our results show that only the activation of ERK MAPK was for IL-1β-induced MUC8 gene although several have that MAPK might be for the signal transduction of various inflammatory mediators G. J. 2001; PubMed Scopus Google Scholar, D. P. S. S. J. 2002; PubMed Scopus Google Scholar, J. PubMed Scopus Google Scholar). Moreover, the ERK MAPK cascade is known to be activated by a protein kinase growth factor and or a and kinase pathway C. Cell 2001; PubMed Scopus Google Scholar). Of these the activation of ERK MAPK is known to be by Ras H.J. Mol. Cell Biol. 1999; PubMed Scopus Google Scholar). In this we investigated IL-1β-induced activation of ERK MAPK is or The overexpression of Raf1 and Ras not the IL-1β-induced phosphorylation of ERK MAPK and MUC8 gene expression and These results show that activation of ERK MAPK by MEK1, as induced by IL-1β, might via a pathway to induce MUC8 gene expression in human airway epithelial cells. is to these the signal molecules involved in the of ERK MAPK, for IL-1β-induced MUC8 gene have not been The of RSK1 and CREB in the of ERK MAPK to induce MUC8 gene expression is a major of the The substrates of ERK MAPK are known to be the and family M. S. Mol. Cell 1999; PubMed Scopus Google Scholar). Our results show that RSK1 might be essential for IL-1β-induced MUC8 gene expression. In addition, the activation of to be to IL-1β-induced MUC5AC gene expression by IL-1β in human airway epithelial cells K.S. Lee W.J. Koo J.S. J.Y. Yoon J.H. J. Biol. Chem. Scholar). in the of these kinases by IL-1β may be responsible for in RSK1 phosphorylates several transcription factors, including CREB J. PubMed Scopus Google Scholar), C. Blenis J. Proc. Natl. Acad. Sci. U. S. A. 1993; 90: PubMed Scopus Google Scholar), protein M. P. M. T. Mol. 1999; Full Text Full Text PDF PubMed Scopus Google Scholar), nuclear Kim Lee Kim Kim J. Biol. Chem. 2001; 276: Full Text Full Text PDF PubMed Scopus Google Scholar), and the J. Blenis J. Mol. Cell Biol. 1998; PubMed Scopus Google Scholar), and with protein known as T. A. J. T. Blenis J. Full Text Full Text PDF PubMed Scopus Google Scholar). studies have that RSK1 phosphorylates of CREB (16Deak M. Clifton A.D. Lucocq L.M. Alessi D.R. EMBO J. 1998; 17: 4426-4441Crossref PubMed Scopus (844) Google Scholar, J.S. P. 2000; PubMed Scopus Google Scholar, J.S. M. J. Biol. Chem. 1998; Full Text Full Text PDF PubMed Scopus Google Scholar, G.R. A. P. J.S. Mol. Cell Biol. 2002; PubMed Scopus Google Scholar). CREB activation by RSK1 has been by previous studies in other cells, and CREB is a of mucin MUC5AC, MUC5B, and gene expression in the of (17Van Seuningen I. Pigny P. Perrais M. Porchet N. Aubert J.P. Front. Biosci. 2001; 6: 1216-1234Crossref PubMed Google Scholar), its in airway epithelial cells. In addition, is known the of CREB in MUC8 gene expression. In the the activation of CREB was at in essential for IL-1β-induced MUC8 gene expression via ERK MAPK and Interestingly, MUC8 gene expression was in CREB cells with In addition, treatment with both and activated the phosphorylation of CREB and increased MUC8 gene expression and These results that CREB might be a transcription factor for IL-1β-induced MUC8 gene expression. However, increased MUC8 expression induced by both and was that induced by IL-1β, that activation by CREB is for IL-1β-induced MUC8 gene expression. These results that a transcription other CREB, may be for IL-1β-induced MUC8 gene expression. We examined IL-1β-induced MUC8 gene expression in human airway epithelial cells is a CRE-mediated transcription. We found that the IL-1β-induced phosphorylation of CREB the to Moreover, IL-1β-induced activation increased in a the overexpression of CREB mutant led to a in the response of the promoter to IL-1β These results showed that the activation of the CRE, to IL-1β-induced MUC8 gene expression in human airway epithelial cells. These results that the MUC8 promoter might have and the might be an important transcription factor of the MUC8 like the mucins of (17Van Seuningen I. Pigny P. Perrais M. Porchet N. Aubert J.P. Front. Biosci. 2001; 6: 1216-1234Crossref PubMed Google Scholar). However, the promoter and cDNA of the MUC8 gene have not been studies the MUC8 promoter In IL-1β was found to induce MUC8 gene expression via the the of RSK1 and CREB are a of the mechanisms that MUC8 gene expression in human airway epithelial cells. Molecular cloning of the MUC8 promoter regulated by various stimuli may yield a deeper insight into cell or function. We are to Dr. Kim for the cDNA construct encoding dominant-negative Raf1