Journal
MOLECULAR PHARMACOLOGY
Volume 70, Issue 3, Pages 1099-1108Publisher
AMER SOC PHARMACOLOGY EXPERIMENTAL THERAPEUTICS
DOI: 10.1124/mol.106.025452
Keywords
-
Categories
Ask authors/readers for more resources
Protein kinase C (PKC) triggers cellular signals that regulate proliferation or death in a cell- and stimulus-specific manner. Although previous studies have demonstrated that activation of PKC with phorbol 12-myristate 13-acetate (PMA) protects cells from apoptosis induced by a number of mechanisms, including death receptor ligation, little is known about the effect or mechanism of PMA in the necrotic cell death. Here, we demonstrate that PMA-mediated activation of PKC protects against tumor necrosis factor (TNF)-induced necrosis by disrupting formation of the TNF receptor (TNFR) 1 signaling complex. Pretreatment with PMA protected L929 cells from TNF-induced necrotic cell death in a PKC-dependent manner, but it did not protect against DNA-damaging agents, including doxorubicin (Adriamycin) and camptothecin. Analysis of the upstream signaling events affected by PMA revealed that it markedly inhibited the TNF-induced recruitment of TNFR1-associated death domain TRADD) and receptor-interacting protein (RIP) to TNFR1, subsequently inhibiting TNF-induced activation of nuclear factor-kappa B and c-Jun NH2-terminal kinase (JNK). However, JNK inhibitors do not significantly affect TNF-induced necrosis, suggesting that the inhibition of JNK activation by PMA is not part of the antinecrotic mechanism. In addition, PMA acted as an antagonist of TNF-induced reactive oxygen species (ROS) production, thereby suppressing activation of ROS-mediated poly(ADP-ribose) polymerase (PARP), and thus inhibiting necrotic cell death. Furthermore, during TNF-induced necrosis, PARP was significantly activated in wild-type mouse embryonic fibroblast (MEF) cells but not in RIP-/- or TNFR-associated factor 2-/- MEF cells. Taken together, these results suggest that PKC activation ensures effective shutdown of the death receptor-mediated necrotic cell death pathway by modulating formation of the death receptor signaling complex.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available