title: Effect of interleukin 1, lipopolysaccharide and phorbol esters on phospholipase D activity in chondrocytes.
abstract: Phorbol 12-myristate 13-acetate (PMA), interleukin-1 (IL-1) and lipopolysaccharide (LPS) induce similar responses in a variety of cell types, including chondrocytes. These responses include the release of arachidonic acid (AA) and the production of prostaglandin E2 (PGE2). Although PMA is known to stimulate phospholipase D (PLD) activity in most cells, it is not known whether LPS and IL-1 also stimulate PLD activity, or whether PLD activity contributes to AA liberation and PGE2 production in chondrocytes. In the present study we compared the effect of IL-1, LPS and protein kinase C (PKC) activators (PMA), mezerein, phorbol dibutyrate on PGE2 synthesis and PLD activity in articular chondrocytes. Although IL-1, LPS and PKC activators stimulate PGE2 synthesis, only the PKC activators stimulated PLD activity. The PKC inhibitor, staurosporine, as well as PKC downregulation, were both found to inhibit PMA-induced PLD activity without inhibiting other PMA-induced effects in chondrocytes. Our data suggest that although chondrocytes contain a PKC-regulated PLD activity, this is not a possible mechanism by which IL-1 or LPS stimulate early events in these cells.
authors.affiliation: Connective Tissue Research Group, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada.
authors.forename: J A
authors.initials: JA
authors.lastname: Conquer
authors.forename: S A
authors.initials: SA
authors.lastname: Jones
authors.forename: T F
authors.initials: TF
authors.lastname: Cruz
mesh_terms: D000818:Animals; D002417:Cattle; D019902:Chondrocytes / Q000187:drug effects* / Q000201:enzymology; D015232:Dinoprostone / Q000096:biosynthesis; D015536:Down-Regulation; D007375:Interleukin-1 / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D010739:Phospholipase D / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives
chemical_list: D007375:Interleukin-1; D008070:Lipopolysaccharides; C020922:4-O-methyl-12-O-tetradecanoylphorbol 13-acetate; D010739:Phospholipase D; D019311:Staurosporine; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate