Mutations to bid cleavage sites protect hepatocytes from apoptosis after ischemia/reperfusion injury.

Abstract

BACKGROUND:

Apoptosis of hepatocytes contributes to many forms of liver pathology and can compromise liver function. Hepatocytes have been shown to require mitochondrial disruption to execute apoptosis, a process that is controlled by members of the Bcl-2 family. Bid is a proapoptotic Bcl-2 family member that is cleaved to its active form, tBid, by caspase 8 and granzyme B. Studies in the Bid-deficient mouse have established that hepatocytes require Bid to undergo apoptosis.

METHODS:

We generated aspartic acid to glutamic acid mutations in the rat Bid protein, at the caspase 8 and granzyme B cleavage sites, and utilized recombinant adenoviruses to express this protein in hepatoma cells and in the livers of rats.

RESULTS:

Cells transduced with recombinant adenoviruses encoding Bid containing mutations to the caspase 8 and granzyme B cleavage sites are significantly protected from both tumor necrosis factor-alpha-induced and cell-mediated apoptosis. Protection occurs through a mechanism that includes decreased Bid cleavage, caspase activation, and mitochondrial membrane damage. Further, after warm ischemia/reperfusion injury, we show that rats expressing cleavage-resistant Bid in the liver display significantly less hepatocyte apoptosis as compared to control rat livers and this results in improved liver function and survival.

CONCLUSION:

Our results suggest that reagents that prevent the cleavage of Bid would be an effective strategy to inhibit hepatocyte apoptosis and decrease liver injury.

• Authors: Erica Riddle-Taylor, Kazuhito Nagasaki, Joseph Lopez, Carlos O Esquivel, Olivia M Martinez, Sheri M Krams
• Journal: Transplantation (Transplantation) Vol. 84 Issue 6 Pg. 778-85 (Sep 27 2007) ISSN: 0041-1337 [Print] United States
• PMID: 17893612 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• BH3 Interacting Domain Death Agonist Protein
• Bid protein, rat
• Aspartic Acid
• Glutamic Acid
• Granzymes
• Caspase 8

Topics

• Amino Acid Sequence
• Amino Acid Substitution
• Animals
• Apoptosis (genetics)
• Aspartic Acid (chemistry, genetics)
• BH3 Interacting Domain Death Agonist Protein (genetics, metabolism)
• Caspase 8 (metabolism)
• Glutamic Acid (chemistry, genetics)
• Granzymes (metabolism)
• Hepatocytes (metabolism, pathology)
• Molecular Sequence Data
• Mutation
• Rats
• Rats, Wistar
• Reperfusion Injury (genetics, pathology, prevention & control)