title: Cholesterol depletion in cell membranes of human airway epithelial cells suppresses MUC5AC gene expression.
abstract: OBJECTIVE
  If cholesterol in the cell membrane is depleted by treating cells with methyl-β-cyclodextrin (MβCD), the activities of transmembrane receptors are altered in a cell-specific and/or receptor-specific manner. The proinflammatory cytokines, IL-1β is potent inducers of MUC5AC mRNA and protein synthesis in human airway epithelial cells. Cells activated by IL-1β showed increased phosphorylation of extracellular signal regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). Thus, we investigated the effects of cholesterol depletion on the expression of MUC5AC in human airway epithelial cells and whether these alterations to MUC5AC expression were related to MAPK activity.
  
  
  METHODS
  After NCI-H292 cells were pretreated with 1% MβCD before adding IL-1β for 24 hours, MUC5AC mRNA expression was determined by reverse transcription- polymerase chain reaction (RT-PCR) and real time-PCR. Cholesterol depletion by MβCD was measured by modified microenzymatic fluorescence assay and filipin staining. The phosphorylation of IL-1 receptor, ERK and p38 MAPK, was analyzed by western blot.
  
  
  RESULTS
  Cholesterol in the cell membrane was significantly depleted by treatment with MβCD on cells. IL-1β-induced MUC5AC mRNA expression was decreased by MβCD and this decrease occurred IL-1-receptor- specifically. Moreover, we have shown that MβCD suppressed the activation of ERK1/2 and p38 MAPK in cells activated with IL-1β. This result suggests that MβCD-mediated suppression of IL-1β-induced MUC5AC mRNA operated via the ERK- and p38 MAPK-dependent pathway.
  
  
  CONCLUSIONS
  Cholesterol depletion in NCI-H292 cell membrane may be considered an anti-hypersecretory method since it effectively inhibits mucus secretion of respiratory epithelial cells.
authors.affiliation: Department of Otorhinolaryngology, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonju-ro, Gangnam-gu, Seoul 135-720, Korea.
authors.forename: Kee Jae
authors.initials: KJ
authors.lastname: Song
authors.forename: Na Hyun
authors.initials: NH
authors.lastname: Kim
authors.forename: Gi Bong
authors.initials: GB
authors.lastname: Lee
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Kwon
authors.forename: Kyung-Su
authors.initials: KS
authors.lastname: Kim
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D055271:Mucin 5AC / Q000235:genetics / Q000378:metabolism*; D012137:Respiratory System / Q000378:metabolism* / Q000473:pathology; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: C524678:MUC5AC protein, human; D055271:Mucin 5AC; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol
keywords: Cholesterol; MAP kinases; cell membrane; cultured cells; mucins
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