Inhibition of NFκB‐mediated pro‐inflammatory gene expression in rat mesangial cells by the enolized 1,3‐dioxane‐4,6‐dione‐5‐carboxamide, CGP‐43182

Abstract

1 CGP-43182 has been described as a potent inhibitor of group IIA secreted phospholipase A 2 (group IIA sPLA 2 ) activity in vitro. In rat mesangial cells, inhibition of group IIA sPLA 2 activity by CGP-43182 results in a 70% reduction of cytokine-stimulated prostaglandin E 2 biosynthesis, suggesting that group IIA sPLA 2 participates in arachidonic acid release and eicosanoid formation. Under these conditions the cytosolic phospholipase A 2 is not aected. 2 In mesangial cells, in addition to inhibition of catalytic activity, the membrane-permeant CGP-43182 completely blocked interleukin 1b (IL1b)-stimulated group IIA sPLA 2 gene expression. 3 A further action of CGP-43182 was a complete inhibition of cyclo-oxygenase-2 gene expression, resulting in a drastic reduction of prostaglandin formation in mesangial cells. 4 Moreover, CGP-43182 completely blocked IL1b-induced gene expression of the inducible nitric oxide synthase, leading to an inhibition of cytokine-stimulated nitric oxide formation. 5 In contrast, the stimulatory eect of the cell-permeant cyclic AMP-analogue, dibutyryl-cAMP, on the induction of these enzymes was not inhibited by CGP-43182. These data indicate that CGP-43182 interferes with IL1b-but not cyclic AMP-activated transcriptional regulation. 6 By studying components of the upstream transcription machinery, we observed an inhibition of NFkB activation by CGP-43182 in IL1b-treated cells. Moreover, we observed that CGP-43182 prevented the phosphorylation and proteolytic degradation of the endogenous NFkB inhibitor, IkB, a process necessary for NFkB activation. 7 From our data, we propose that CGP-43182 is a potent anti-in¯ammatory drug useful for preventing the consequences of a concerted action of cytokine-stimulated pro-in¯ammatory genes mediated by NFkB.

Inhibition of Cytokine-induced Matrix Metalloproteinase 9 Expression by Peroxisome Proliferator-activated Receptor α Agonists Is Indirect and Due to a NO-mediated Reduction of mRNA Stability

“…Moreover, in the complete promoter context additional regulatory events affecting transcriptional activators or repressors may explain the lack of MMP-9 mRNA increase in the absence of cytokine-induced signals. In line with these observations, the potentiating effects of PPAR␣ agonists on cytokine-induced sPLA2 promoter activity in rat MC, similar to their effects on MMP-9 expression, cause activation of the sPLA2 promoter without having significant effects on the basal sPLA2 mRNA steady-state level (30).…”

Potentiation of Tumor Necrosis Factor α-induced Secreted Phospholipase A2 (sPLA2)-IIA Expression in Mesangial Cells by an Autocrine Loop Involving sPLA2 and Peroxisome Proliferator-activated Receptor α Activation

“…A similar effect was observed in the present study for docosahexaenoic acid or linoleic acid as potential PPAR␣ agonists. This suggests that PPAR␣ acts synergistically with other cytokine-activated transcription factors such as NF-B, which was shown earlier to be a major player in the cytokine-dependent induction of sPLA 2 -IIA gene expression in rat mesangial cells (10,11). A further possibility is that the cytokine treatment might be important for the stabilization of the sPLA 2 -IIA mRNA, which would otherwise be rapidly degraded.…”

“…Briefly, assay mixtures (1 ml) contained 100 mM TrisHCl (pH 7.0), 10 mM CaCl 2 , [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]oleate-labeled E. coli (Ϸ10,000 cpm), and 5 l of cell supernatants, which produces less than 5% of substrate hydrolysis. Reaction mixtures were incubated for 30 min at 37°C in a thermomixer.…”

Search of Factors That Intermediate Cytokine-induced Group IIAPhospholipase A2 Expression through the Cytosolic PhospholipaseA2- and 12/15-Lipoxygenase-dependentPathway

“…Indeed, several 12/15-LOX-responsive genes listed in Table I, Because the products of 12/15-LOX can activate PPARs (35,36), some of the 12/15-LOX-induced genes might be regulated by this particular class of nuclear receptors. Indeed, the promoter regions of the genes for some FABPs, including A-FABP, as well as that for sPLA 2 -IIA, contain PPRE elements to which PPARs can bind and thereby transactivate their target genes (34,(43)(44)(45). Although our present EMSA analysis argues against a requirement for the reported PPAR␥-binding element (Ϫ160 to Ϫ133) in the sPLA 2 -IIA promoter (34) for 12/15-LOXdependent induction of this enzyme, the promoter region may contain additional PPAR-responsive element(s) that could account for PPAR-dependent induction of sPLA 2 -IIA.…”