title: Activation of p55 tumor necrosis factor-alpha receptor-1 coupled to tumor necrosis factor receptor-associated factor 2 stimulates intercellular adhesion molecule-1 expression by modulating a thapsigargin-sensitive pathway in human tracheal smooth muscle cells.
abstract: Tumor necrosis factor-alpha (TNFalpha) stimulates the expression of intercellular adhesion molecule-1 (ICAM-1) by activating the transcription factor nuclear factor-kappaB (NF-kappaB) in human airway smooth muscle (ASM) cells. This study characterizes the receptor involved as well as critical downstream signaling events mediating cytokine-induced NF-kappaB activation and ICAM-1 expression. TNFalpha stimulation for 1 to 4 h induced ICAM-1 expression in human ASM cells. This rapid TNFalpha-induced ICAM-1 expression enhanced T-lymphocyte adhesion to ASM cells, which was inhibited by anti-ICAM-1 antibodies. Using immunostaining, we demonstrated that TNFalpha receptors TNFR1 and TNFR2 are expressed on native human tracheal smooth muscle. Treatment of cells with htr-9, an antibody that specifically activates TNFR1, also stimulated expression of ICAM-1 mRNA and protein. Utr-1, a blocking antibody to TNFR2, did not affect TNFalpha-mediated ICAM-1 expression. Both TNFalpha and htr-9 increased luciferase activity in ASM cells transfected with a NF-kappaB reporter plasmid. Overexpression of a dominant negative TNF receptor-associated factor 2 construct, lacking the NH(2)-terminal RING finger, completely abrogated both TNFalpha- and htr-9-mediated increases in NF-kappaB reporter activity. Thapsigargin, an agent that depletes intracellular calcium stores, abrogated both cytokine-mediated NF-kappaB-dependent ICAM-1 mRNA transcription and protein expression but had no effect on IkappaB degradation. In addition, chelating cytosolic calcium with 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid acetoxymethyl ester also inhibited cytokine TNFalpha-induced ICAM-1 expression. These data suggest that TNFR1, through a TNF receptor-associated factor 2-NF-kappaB signaling pathway, mediates TNFalpha-induced expression of ICAM-1 on ASM cells by involving a thapsigargin-sensitive signaling pathway.
authors.affiliation: Pulmonary, Allergy and Critical Care Division, Department of Medicine, University of Pennsylvania Medical Center, Philadelphia 19104-6160, USA. amrani@mail.med.upenn.edu
authors.forename: Y
authors.initials: Y
authors.lastname: Amrani
authors.forename: A L
authors.initials: AL
authors.lastname: Lazaar
authors.forename: R
authors.initials: R
authors.lastname: Hoffman
authors.forename: K
authors.initials: K
authors.lastname: Amin
authors.forename: S
authors.initials: S
authors.lastname: Ousmer
authors.forename: R A
authors.initials: RA
authors.lastname: Panettieri
mesh_terms: D015703:Antigens, CD / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D008213:Lymphocyte Activation; D009130:Muscle, Smooth / Q000378:metabolism*; D016328:NF-kappa B / Q000502:physiology; D011506:Proteins / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism / Q000502:physiology*; D047888:Receptors, Tumor Necrosis Factor, Type I; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D047992:TNF Receptor-Associated Factor 2; D019284:Thapsigargin / Q000494:pharmacology; D014132:Trachea / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D015703:Antigens, CD; D004791:Enzyme Inhibitors; D016328:NF-kappa B; D011506:Proteins; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047992:TNF Receptor-Associated Factor 2; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D019284:Thapsigargin