cFLIP-L inhibits p38 MAPK activation. An additional anti-apoptotic mechanism in bile acid-mediated apoptosis

Annette Grambihler, Hajime Higuchi, Steven F. Bronk, Gregory J. Gores

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

In cholestasis, toxic bile acids accumulate within the liver inducing hepatocyte apoptosis, which exacerbates liver injury. Although bile acids activate both death receptors and mitogen-activated kinase (MAPK) pathways, the mechanistic link between death receptor signaling and MAPK activation in bile acid apoptosis remains unclear. The aim of this study was to ascertain if MAPKs contribute to bile acid cytotoxicity. Although deoxycholate induced apoptosis and activated all three classic mediators of the MAPK pathways including JNK 1/2, p38, and p42/44, only p38 MAPK inhibition attenuated apoptosis. Suppressing FADD expression with siRNA or employing a caspase inhibitor, zVAD-fmk, did not block p38 MAPK activation suggesting its activation was not death receptor-dependent. Unexpectedly, expression of cFLIP-L in a stably transfected cell line blocked apoptosis and p38 MAPK phosphorylation. Based on these data we postulated a direct effect of cFLIP on p38 MAPK activation. The nonphosphorylated but not the phosphorylated/active form of p38 MAPK co-immunoprecipitated with cFLIP-L. In reverse immunoprecipitation experiments, cFLIP-L long but not cFLIP-S co-immunoprecipitate with p38 MAPK. In conclusion, these data suggest that cFLIP-L exerts its antiapoptotic activity, in part, by inhibiting p38 MAPK activation, an additional anti-apoptotic effect for this protein.

Original languageEnglish (US)
Pages (from-to)26831-26837
Number of pages7
JournalJournal of Biological Chemistry
Volume278
Issue number29
DOIs
StatePublished - Jul 18 2003

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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