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The adenylate cyclase activator forskolin partially protects L929 cells against tumour necrosis factor-alpha-mediated cytotoxicity via a cAMP-independent mechanism


Uboldi, AD; Savage, N
2002-09-07
CYTOKINE
Journal Article
19
5
250-258
Recent reports indicate that cAMP-elevating agents can protect against cell death induced by many stimuli, including tumour necrosis factor-alpha (TNF-alpha). We investigated the ability of cAMP-elevating agents to modulate TNF-alpha-mediated cytotoxicity in L929 cells. Using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) reduction assay and a DNA fragmentation assay as indicators of cell survival, we have shown that forskolin confers partial protection against TNF-a-mediated cytotoxicity and inhibits TNF-alpha-induced internucleosomal DNA fragmentation in L929 cells. The protection conferred by forskolin is cAMP-independent since 1,9-dideoxyforskolin (an adenylate cyclase-inactive analog) also protected against TNF-alpha, while both dibutyryl-cAMP and the cAMP-phosphodiesterase inhibitor theophylline were not protective. This is the first example (that we know of) of cAMP-independent cytoprotection by forskolin. We conclude that forskolin acts in a cAMP-independent manner, potentially at a site upstream of caspase-3 activation, to protect against TNF-a-mediated cytotoxicity in L929 cells, and that cAMP elevation, in general, does not confer protection against TNF-alpha-induced death in L929 cells. In addition, we observed that Cyclosporin A, a mitochondrial permeability transition (MPT) inhibitor, protected L929 cells against TNF-alpha, underlining the importance of mitochondria in the cytotoxic process induced by TNF-alpha in L929 cells. (C) 2002 Elsevier Science Ltd. All rights reserved.
ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD
PERMEABILITY TRANSITION PORE; NF-KAPPA-B; MANGANOUS SUPEROXIDE-DISMUTASE; ARACHIDONIC-ACID METABOLISM; FAS-INDUCED APOPTOSIS; CYTOCHROME-C RELEASE; CYTO-TOXICITY; CYCLOSPORINE-A; DNA FRAGMENTATION; INNER MEMBRANE
10.1006/cyto.2002.1969
Refer to copyright notice on published article.

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Creation Date 2002-09-07 12:00:00