title: Tumor necrosis factor-alpha induces the 85-kDa cytosolic phospholipase A2 gene expression in human bronchial epithelial cells.
abstract: Phospholipase A2 (PLA2) activity has been suggested to mediate some of the tumor necrosis factor (TNF) induced cellular responses including cytotoxicity. We evaluated the induction of both the 85-kDa cytosolic phospholipase A2 (cPLA2) and non-pancreatic group II PLA2 gene expression by TNF-alpha in a human bronchial epithelial cell line (BEAS 2B cell). TNF-alpha (20 ng/ml) induced a significantly increased release of prelabeled [3H]arachidonic acid (AA) following 4-24 h incubation. Calcium ionophore A23187 (10(-5) M) further increased the [3H]AA release from the TNF-alpha-treated cells. In vitro activity assay revealed that TNF-alpha increased the dithiothreitol (DTT)-resistant PLA2 activity which was blocked by the cPLA2 inhibitor AACOCF3. Treatment with TNF-alpha for 4-24 h increased the cPLA2 protein and mRNA levels which were blocked by the broad inhibitor of protein kinases staurosporine, the protein kinase C (PKC) inhibitor calphostin C, and to a lesser extent the calcium/calmodulin-dependent protein kinase inhibitor W-7. Reverse transcription and polymerase chain reaction amplification of the group II PLA2 mRNA showed that it is expressed in human lung but not in the bronchial epithelial cell line. TNF-alpha failed to induce the expression of group II PLA2 in the BEAS 2B cells. These results demonstrate that the cPLA2 gene expression is up-regulated by TNF-alpha and this effect may contribute to the TNF-alpha stimulated AA release in airway epithelial cells.
authors.affiliation: Critical Care Medicine Department, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: T
authors.initials: T
authors.lastname: Wu
authors.forename: T
authors.initials: T
authors.lastname: Ikezono
authors.forename: C W
authors.initials: CW
authors.lastname: Angus
authors.forename: J H
authors.initials: JH
authors.lastname: Shelhamer
mesh_terms: D016718:Arachidonic Acid / Q000378:metabolism; D001483:Base Sequence; D001980:Bronchi / Q000166:cytology / Q000201:enzymology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D017931:DNA Primers / Q000737:chemistry; D004848:Epithelium / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D008969:Molecular Sequence Data; D010741:Phospholipases A / Q000235:genetics*; D054467:Phospholipases A2; D012333:RNA, Messenger / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D017931:DNA Primers; D007476:Ionophores; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D016718:Arachidonic Acid; D000001:Calcimycin; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium