Bile acid regulation of C/EBPbeta, CREB, and c-Jun function, via the extracellular signal-regulated kinase and c-Jun NH2-terminal kinase pathways, modulates the apoptotic response of hepatocytes

Mol Cell Biol. 2003 May;23(9):3052-66. doi: 10.1128/MCB.23.9.3052-3066.2003.

Abstract

Previously, we have demonstrated that deoxycholic acid (DCA)-induced signaling of extracellular signal-regulated kinases 1 and 2 (ERK1/2) in primary hepatocytes is a protective response. In the present study, we examined the roles of the ERK and c-Jun NH(2)-terminal kinase (JNK) pathways, and downstream transcription factors, in the survival response of hepatocytes. DCA caused activation of the ERK1/2 and JNK1/2 pathways. Inhibition of either DCA-induced ERK1/2 or DCA-induced JNK1/2 signaling enhanced the apoptotic response of hepatocytes. Further analyses demonstrated that DCA-induced JNK2 signaling was cytoprotective whereas DCA-induced JNK1 signaling was cytotoxic. DCA-induced ERK1/2 activation was responsible for increased DNA binding of C/EBPbeta, CREB, and c-Jun/AP-1. Inhibition of C/EBPbeta, CREB, and c-Jun function promoted apoptosis following DCA treatment, and the level of apoptosis was further increased in the case of CREB and c-Jun, but not C/EBPbeta, by inhibition of MEK1/2. The combined loss of CREB and c-Jun function or of C/EBPbeta and c-Jun function enhanced DCA-induced apoptosis above the levels resulting from the loss of either factor individually; however, these effects were less than additive. Loss of c-Jun or CREB function correlated with increased expression of FAS death receptor and PUMA and decreased expression of c-FLIP-(L) and c-FLIP-(S), proteins previously implicated in the modulation of the cellular apoptotic response. Collectively, these data demonstrate that multiple DCA-induced signaling pathways and transcription factors control hepatocyte survival.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / physiology
  • Bile Acids and Salts / metabolism*
  • CASP8 and FADD-Like Apoptosis Regulating Protein
  • CCAAT-Enhancer-Binding Proteins / genetics
  • CCAAT-Enhancer-Binding Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Cells, Cultured
  • Cyclic AMP Response Element-Binding Protein / genetics
  • Cyclic AMP Response Element-Binding Protein / metabolism*
  • Deoxycholic Acid / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Hepatocytes / cytology
  • Hepatocytes / drug effects
  • Hepatocytes / metabolism*
  • Intracellular Signaling Peptides and Proteins*
  • JNK Mitogen-Activated Protein Kinases
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mitogen-Activated Protein Kinase 9
  • Mitogen-Activated Protein Kinases / drug effects
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism*
  • Molecular Sequence Data
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction / drug effects
  • Signal Transduction / physiology
  • Transcription Factor AP-1 / drug effects
  • Transcription Factor AP-1 / genetics
  • Transcription Factor AP-1 / metabolism
  • fas Receptor / drug effects
  • fas Receptor / metabolism

Substances

  • Bile Acids and Salts
  • CASP8 and FADD-Like Apoptosis Regulating Protein
  • CCAAT-Enhancer-Binding Proteins
  • Carrier Proteins
  • Cflar protein, mouse
  • Cyclic AMP Response Element-Binding Protein
  • Enzyme Inhibitors
  • Intracellular Signaling Peptides and Proteins
  • Transcription Factor AP-1
  • fas Receptor
  • Deoxycholic Acid
  • Mitogen-Activated Protein Kinase 9
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases