title: Mitogen-activated protein kinase activation regulates intestinal epithelial differentiation.
abstract: OBJECTIVE
  The human colon cancer-derived cell line HT29 displays a multipotent phenotype. A subclone of HT29 cells containing numerous mucous granules and termed HT29-18-N2 was studied to determine the cellular mechanisms underlying a switch to the differentiated phenotype.
  
  
  METHODS
  Northern (RNA) blotting, immunoblotting, and immunocytochemistry of HT29-N2 cells, grown under glucose-containing and glucose-free conditions with or without the use of the mitogen-activated protein (MAP) kinase kinase (MEK) inhibitor PD98059, were performed.
  
  
  RESULTS
  Loss of activation of the MAP kinases ERK 1 and ERK 2 in HT29-N2 cells upon a change to glucose-free growth medium preceded the change in phenotype and up-regulation of the goblet cell gene product intestinal trefoil factor (ITF). Long-term pharmacological MAP kinase inhibition with the MEK inhibitor PD98059 induced expression of the terminal differentiation markers ITF, sucrase-isomaltase, and the mucin gene MUC2. This was accompanied by morphological evidence of gland formation and mucin secretion and the appearance of discrete goblet cell and enterocyte populations. Induction of ITF and sucrase-isomaltase after MEK inhibition in HT29-N2 cells did not involve loss of MAP kinase responsiveness and was not mediated by receptor tyrosine kinases.
  
  
  CONCLUSIONS
  Regulation of ERK activation may be a key biochemical switch responsible for terminal differentiation of components of the crypt-villus unit.
authors.affiliation: Gastrointestinal Unit and Center for the Study of Inflammatory Bowel Disease, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: D
authors.initials: D
authors.lastname: Taupin
authors.forename: D K
authors.initials: DK
authors.lastname: Podolsky
mesh_terms: D000943:Antigens, Differentiation / Q000378:metabolism; D015152:Blotting, Northern; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D048429:Cell Size / Q000187:drug effects; D002999:Clone Cells / Q000187:drug effects; D003470:Culture Media; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005947:Glucose / Q000502:physiology; D006133:Growth Substances / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000166:cytology*; D048369:MAP Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009077:Mucins; D009124:Muscle Proteins; D009479:Neuropeptides; D010455:Peptides / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000071164:Trefoil Factor-2; D000071165:Trefoil Factor-3
chemical_list: D000943:Antigens, Differentiation; D003470:Culture Media; D004791:Enzyme Inhibitors; D005419:Flavonoids; D006133:Growth Substances; D009077:Mucins; D009124:Muscle Proteins; D009479:Neuropeptides; D010455:Peptides; C099037:TFF3 protein, rat; D000071164:Trefoil Factor-2; D000071165:Trefoil Factor-3; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D005947:Glucose; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one