title: Polyamines regulate E-cadherin transcription through c-Myc modulating intestinal epithelial barrier function.
abstract: The integrity of the intestinal epithelial barrier depends on intercellular junctions that are highly regulated by numerous extracellular and intracellular factors. E-cadherin is found primarily at the adherens junctions in the intestinal mucosa and mediates strong cell-cell contacts that have a functional role in forming and regulating the epithelial barrier. Polyamines are necessary for E-cadherin expression, but the exact mechanism underlying polyamines remains elusive. The current study was performed to determine whether polyamines induce E-cadherin expression through the transcription factor c-Myc and whether polyamine-regulated E-cadherin plays a role in maintenance of the epithelial barrier integrity. Decreasing cellular polyamines reduced c-Myc and repressed E-cadherin transcription as indicated by a decrease in levels of E-cadherin promoter activity and its mRNA. Forced expression of the c-myc gene by infection with adenoviral vector containing c-Myc cDNA stimulated E-cadherin promoter activity and increased E-cadherin mRNA and protein levels in polyamine-deficient cells. Experiments using different E-cadherin promoter mutants revealed that induction of E-cadherin transcription by c-Myc was mediated through the E-Pal box located at the proximal region of the E-cadherin promoter. Decreased levels of E-cadherin in polyamine-deficient cells marginally increased basal levels of paracellular permeability but, remarkably, potentiated H(2)O(2)-induced epithelial barrier dysfunction. E-cadherin silencing by transfection with its specific small interfering RNA also increased vulnerability of the epithelial barrier to H(2)O(2). These results indicate that polyamines enhance E-cadherin transcription by activating c-Myc, thus promoting function of the epithelial barrier.
authors.affiliation: Cell Biology Group, Department of Surgery, University of Maryland School of Medicine, Baltimore, Maryland, USA.
authors.forename: Lan
authors.initials: L
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Guo
authors.forename: Jaladanki N
authors.initials: JN
authors.lastname: Rao
authors.forename: Tongtong
authors.initials: T
authors.lastname: Zou
authors.forename: Lan
authors.initials: L
authors.lastname: Xiao
authors.forename: Tingxi
authors.initials: T
authors.lastname: Yu
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Timmons
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Turner
authors.forename: Jian-Ying
authors.initials: JY
authors.lastname: Wang
mesh_terms: D000818:Animals; D015703:Antigens, CD; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D000518:Eflornithine / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D007365:Intercellular Junctions / Q000187:drug effects / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation; D009955:Ornithine Decarboxylase / Q000378:metabolism; D065108:Ornithine Decarboxylase Inhibitors; D010539:Permeability; D011073:Polyamines / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D004791:Enzyme Inhibitors; C489427:MYC protein, human; D065108:Ornithine Decarboxylase Inhibitors; D011073:Polyamines; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D006861:Hydrogen Peroxide; D009955:Ornithine Decarboxylase; D000518:Eflornithine