Enhancement of cAMP levels and of protein kinase activity by tumor necrosis factor and interleukin 1 in human fibroblasts: role in the induction of interleukin 6.

Abstract

Although tumor necrosis factor (TNF) and interleukin 1 (IL-1) affect many cell functions, the molecular mechanisms of TNF and IL-1 action are not understood. Our present study shows that exposure of human FS-4 fibroblasts to TNF or IL-1 caused a rapid accumulation of intracellular cAMP and an increase in protein kinase activity. Intracellular cAMP levels peaked 3-5 min after the addition of TNF or IL-1 and returned to basal level by 15 min. Increased phosphorylation of histone 1H1-B protein was demonstrated with extracts prepared from TNF-or IL-i-treated cells, suggesting an increase in cAMP-dependent protein kinase activity. No evidence was obtained for protein kinase C activation in TNFtreated FS-4 cells. TNF, IL-1, and forskolin all stimulated interleukin 6 (IL-6) mRNA levels in FS4 cells. The protein kinase inhibitor H-8, inhibiting preferentially cAMPdependent kinase activity, reduced forskolin-stimulated IL-6 mRNA induction more strongly than TNF-or IL-i-driven IL-6 mRNA induction. These results suggest that activation of cAMP-dependent protein kinase by TNF and IL-1 is important in some actions of these cytokines. In addition, our data on IL-6 induction by TNF and IL-1 suggest that other, yet unidentified, signal transduction mechanisms contribute to TNF and IL-1 actions on gene expression in human fibroblasts.The cytokines tumor necrosis factor (TNF) and interleukin 1 (IL-1) mediate a variety of actions important in host defense, inflammation, and autoimmunity (reviewed in refs. 1-3). Although unrelated to each other in their amino acid sequences and known to recognize separate receptors, TNF and IL-1 are surprisingly similar in many of their actions (reviewed in ref.3). In cultured cells, TNF and IL-1 were shown to cause activation of the same genes-e.g., both induce IL-1 synthesis in monocytes or endothelial cells (4, 5), both cause a similar enhancement of c-fos and c-myc protooncogene mRNA levels in human fibroblasts (6), and both induce interleukin 6 (IL-6) (7,8). [IL-6 is also known as interferon-p2 (9), 26-kDa protein (10), B-cell stimulatory factor 2 (11), and hepatocyte stimulatory factor (12).] The similarity in the actions of TNF and IL-1 suggests that they activate similar intracellular pathways, but virtually nothing is known about the molecular mechanisms of their actions.The increase in IL-6 mRNA levels by TNF or IL-1 in human fibroblasts is demonstrable within 1 hr, and it is accompanied by an increase in the rate of IL-6 mRNA transcription (13). In a recent paper, we showed that IL-6 is rapidly induced by various treatments that enhance intracellular cAMP levels and we suggested that the induction of by TNF and IL-1 also may involve the cAMP pathway (14).In this paper, we show that both TNF and IL-1 cause a rapid and transient increase in intracellular cAMP and an increase in protein kinase activity in human fibroblasts. Results Research, Osaka, Japan). Recombinant E. coli-derived human IL-la (3 x 107 units/ mg) was obtained from P. Lomedico (Hoffmann-La Roche).The plasmid P-...

Synergy between Tumor Necrosis Factor α and Interleukin 1β in Inducing Transcriptional Down-regulation of Muscarinic M2 Receptor Gene Expression

“…This inhibitor provided slight but significant protection against TNF␣-and IL-1␤-induced M 2 receptor mRNA downregulation, suggesting that PKA is involved, at least in part, in receptor modulation by TNF-␣ and IL-1␤. This finding is in agreement with data showing that the PKA signal transduction pathway is important in TNF-␣ and IL-1␤ induction of IL-6 mRNA in human fibroblasts (32). In view of the pleiotropic nature of TNF-␣ and IL-1␤, it is not surprising that several alternative pathways can be activated by these cytokines.…”

Tumor necrosis factor α (TNFα) induces pro‐matrix metalloproteinase 9 production in human uterine cervical fibroblasts but interleukin 1 α antagonizes the inductive effect of TNFα

“…This was further confirmed by down-regulation of PKC in which the cells were pretreated with TPA (100 nM) for 24 h prior to stimulation with TNFa (T. Sato, A. Ito and Y. Mori, unpublished data). The PKC-independent signal pathway of TNFc~ has been reported for other cells [23][24][25]. Thus, we conclude that in cervical fibroblasts TNFa possesses at least two distinct signal transduction pathways after binding to its receptor: one is a PKC-independent pathway which leads to augmentation of the proMMP-9 production; and the other is the Confluent cervical fibroblasts at the 3rd passage were treated with rhTNF~ (10 ng/ml), TPA (10 nM) and/or rhlL-loc (10 ng/ml) in the presence of ~taurosporine (5-20 nM) for 18 h. The harvested culture media were analyzed for the production of proMMP-9 and proMMP-3 by Western blot .malysis.…”

Effect of cyclic GMP‐dependent vasodilators on the expression of inducible nitric oxide synthase in vascular smooth muscle cells: role of cyclic AMP

“…Activation of the type I IL-1 receptor leads to increases in the intracellular level of cyclic AMP via a G-protein coupled activation of adenylyl cyclase and activation of protein kinase(s) A in murine fibroblasts and thymocytes (Zhang et al, 1988;Shirakawa et al, 1988;Chedid et al, 1989). A potentiation of the activity of adenylyl cyclase by IL-1,B was also found in vascular smooth muscle cells as indicated by the timedependent accumulation of cyclic AMP (Scott-Burden et al, 1994;this study).…”