title: Mitogen-activated protein kinase phosphatase-1 prevents lipopolysaccharide-induced apoptosis in immature rat intestinal epithelial cells.
abstract: BACKGROUND
  Necrotizing enterocolitis is characterized by intestinal inflammation and epithelial barrier dysfunction. Mitogen-activated protein kinase (MAPK) phosphatase (MKP)-1 plays a pivotal role in the feedback control of MAPK signaling, which regulates inflammation and apoptosis. We hypothesized that MKP-1 prevents lipopolysaccharide (LPS)-induced apoptosis in intestinal epithelial cells.
  
  
  METHODS
  Western blot analysis and qPCR were used to assess MKP-1, MAPK (p38, extracellular signal-regulated kinase (ERK), and c-Jun N terminal kinases (JNK)), caspase 3, caspase 9, tumor necrosis factor (TNF)-α, and cyclooxygenase (COX)-2 expression levels in rIEC-6 enterocytes. MKP-1 expression was inhibited using small interfering RNA (siRNA) methodology. Viable cell number was determined using trypan blue exclusion.
  
  
  RESULTS
  LPS stimulation led to activation of p38, JNK, and ERK, and induction of MKP-1 mRNA and protein expression. The induction of MKP-1 was associated with a decrease in p38 phosphorylation, and knockdown of MKP-1 prolonged p38 phosphorylation. While LPS stimulation significantly attenuated proliferation of rIEC-6 cells transfected with scramble siRNA, LPS stimulation resulted in a net decrease in viable cell number in cells transfected with MKP-1 siRNA. Following LPS stimulation, MKP-1 knockdown resulted in greater caspase 3 and 9 activities and greater proinflammatory cytokine (TNF-α, COX-2) expression than in cells transfected with scramble siRNA.
  
  
  CONCLUSIONS
  Our results demonstrate that MKP-1 has a central role in preventing inflammation-induced apoptosis in rIEC-6 enterocytes.
authors.affiliation: 1] Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio [2] Department of Pediatrics, The Ohio State University, Columbus, Ohio.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Talavera
authors.affiliation: Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio.
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Kralik
authors.affiliation: Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio.
authors.forename: Yi
authors.initials: Y
authors.lastname: Jin
authors.affiliation: 1] Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio [2] Department of Pediatrics, The Ohio State University, Columbus, Ohio.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Chen
authors.affiliation: 1] Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio [2] Department of Pediatrics, The Ohio State University, Columbus, Ohio.
authors.forename: Yusen
authors.initials: Y
authors.lastname: Liu
authors.affiliation: 1] Center for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio [2] Department of Pediatrics, The Ohio State University, Columbus, Ohio.
authors.forename: Leif D
authors.initials: LD
authors.lastname: Nelin
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism; D054638:Dual Specificity Phosphatase 1 / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D055785:Gene Knockdown Techniques; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects*; D008070:Lipopolysaccharides / Q000633:toxicity*; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D051546:Cyclooxygenase 2; D054638:Dual Specificity Phosphatase 1