title: Notch signaling downregulates MUC5AC expression in airway epithelial cells through Hes1-dependent mechanisms.
abstract: BACKGROUND
  Mucus overproduction is one of the major pathological features of asthma, and MUC5AC is the major mucin component of airway mucus. However, whether Notch signaling is implicated in the regulation of MUC5AC expression in airway secretary cells is still undetermined.
  
  
  OBJECTIVE
  The aim of this study is to examine whether Notch signaling can regulate MUC5AC expression and explore the molecular mechanisms.
  
  
  METHODS
  Mouse mtCC1-2 cells and human NCI-H292 cells were transfected with NIC, and MUC5AC expression was examined. Using gene reporter assays, site-directed mutagenesis, and ChIP assays, the activity of both mouse and human MUC5AC promoter was analyzed.
  
  
  RESULTS
  Notch signaling regulated MUC5AC expression both in mouse mtCC1-2 cells and in human NCI-H292 cells. Several Hes-binding site N-boxes were identified in the 5' region of both mouse and human MUC5AC promoters. Overexpression of NIC resulted in activation of the MUC5AC promoter. Site-directed mutagenesis report assays revealed that Hes proteins might repress both mouse and human MUC5AC promoter activity. Furthermore, ChIP assays confirmed that Hes1 binds to the MUC5AC promoter both in mouse mtCC1-2 cells and in human NCI-H292 cells.
  
  
  CONCLUSIONS
  Notch signaling can directly downregulate MUC5AC promoter activity through Hes1-dependent mechanisms, which may be identified as possible targets for pharmacotherapy of airway mucus hypersecretion in asthma.
authors.affiliation: Department of Respiratory Medicine, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Hai-Feng
authors.initials: HF
authors.lastname: Ou-Yang
authors.forename: Chan-Gui
authors.initials: CG
authors.lastname: Wu
authors.forename: Shuo-Yao
authors.initials: SY
authors.lastname: Qu
authors.forename: Zhi-Kui
authors.initials: ZK
authors.lastname: Li
mesh_terms: D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D015536:Down-Regulation; D018398:Homeodomain Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D055271:Mucin 5AC / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D051880:Receptors, Notch / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000378:metabolism*; D016415:Sequence Alignment; D000072056:Transcription Factor HES-1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D055271:Mucin 5AC; D051880:Receptors, Notch; D000072056:Transcription Factor HES-1; C489734:Hes1 protein, mouse; C524678:MUC5AC protein, human; C524679:Muc5ac protein, mouse; C078493:HES1 protein, human