S-adenosyl-methionine decreases ethanol-induced apoptosis in primary hepatocyte cultures by a c-Jun N-terminal kinase activity-independent mechanism.

Abstract

AIM:

To determine the role of c-Jun N-terminal kinase (JNK) activity in ethanol-induced apoptosis and the modulation of this signaling cascade by S-Adenosyl-methionine (AdoMet).

METHODS:

Primary hepatocyte cultures were pretreated with 100 micromol/L SP600125, a selective JNK inhibitor, 1 mL/L DMSO or 4 mmol/L AdoMet and then exposed to 100 mmo/L ethanol. Hepatocyte apoptosis was determined by the TUNEL and DNA ladder assays. JNK activity and its inhibition by SP600125 and AdoMet were determined by Western blot analysis of c-jun phosphorylation and Bid fragmentation. SP600125 and AdoMet effects on the apoptotic signaling pathway were determined by Western blot analysis of cytochrome c release and pro-caspase 3 fragmentation. The AdoMet effect on glutathione levels was measured by Ellman's method and reactive oxygen species (ROS) generation by cell cytometry.

RESULTS:

The exposure of hepatocytes to ethanol induced JNK activation, c-jun phosphorylation, Bid fragmentation, cytochrome c release and pro-caspase 3 cleavage; these effects were diminished by SP600125, and caused a significant decrease in ethanol-induced apoptosis (P< 0.05). AdoMet exerted an antioxidant effect maintaining glutathione levels and decreasing ROS generation, without a significant effect on JNK activity, and prevented cytochrome c release and pro-caspase 3 cleavage.

CONCLUSION:

The JNK signaling cascade is a key component of the proapoptotic signaling pathway induced by ethanol. JNK activation may be independent from ROS generation, since AdoMet which exerted antioxidant properties did not have a significant effect on JNK activity. JNK pathway modulator agents and AdoMet may be components of promising therapies for alcoholic liver disease (ALD) treatment.

• Authors: Maria del Pilar Cabrales-Romero, Lucrecia Márquez-Rosado, Samia Fattel-Fazenda, Cristina Trejo-Solís, Evelia Arce-Popoca, Leticia Alemán-Lazarini, Saúl Villa-Treviño
• Journal: World journal of gastroenterology (World J Gastroenterol) Vol. 12 Issue 12 Pg. 1895-904 (Mar 28 2006) ISSN: 1007-9327 [Print] United States
• PMID: 16609996 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anthracenes
• BH3 Interacting Domain Death Agonist Protein
• Bid protein, rat
• Reactive Oxygen Species
• pyrazolanthrone
• Ethanol
• S-Adenosylmethionine
• Cytochromes c
• JNK Mitogen-Activated Protein Kinases
• Casp3 protein, rat
• Caspase 3
• Caspases
• Glutathione

Topics

• Animals
• Anthracenes (pharmacology)
• Apoptosis (drug effects, physiology)
• BH3 Interacting Domain Death Agonist Protein (metabolism)
• Caspase 3
• Caspases (metabolism)
• Cells, Cultured
• Cytochromes c (metabolism)
• Ethanol (pharmacology)
• Glutathione (metabolism)
• Hepatocytes (drug effects, physiology)
• JNK Mitogen-Activated Protein Kinases (antagonists & inhibitors, physiology)
• Male
• Mitochondria
• Rats
• Rats, Inbred F344
• Reactive Oxygen Species (metabolism)
• S-Adenosylmethionine (pharmacology)
• Signal Transduction (drug effects, physiology)