Deficiency of survivin in transgenic mice exacerbates Fas-induced apoptosis via mitochondrial pathways.
OBJECTIVE
Survivin is an inhibitor of apoptosis protein (IAP), which also is crucial for mitosis and cell cycle progression. IAPs participate in regulating Fas ligand-induced hepatic apoptosis. The aim was to study the contribution of survivin to hepatic apoptosis by generating transgenic mice lacking survivin.


METHODS
The survivin gene was inactivated in mice by homologous recombination in embryonic stem cells. Survivin+/- and survivin+/+ mice were generated and injected with the Fas agonistic antibody Jo2.


RESULTS
In 3 genetic backgrounds, survivin-/- embryos died before 4.5 days post coitum. Survivin+/- mice appeared normal, but liver lysates revealed baseline low-level activation of procaspase-8, Bid, procaspase-9, and procaspase-3, with accumulation of Bax, and release of cytochrome c, indicating a proapoptotic state. Intraperitoneal injection of low-dose Jo2 had no effect on survivin+/+ mice at 2 hours. However, in survivin+/- mice, Jo2 caused hemorrhagic necrosis of the liver, associated with prominent activation of the apoptotic pathway via the mitochondria, and up-regulation of hepatocellular expression of survivin in the cytosol, nuclei, and mitochondria. Isolated mitochondria from survivin+/- livers had more defects in oxidative phosphorylation after C(2)-ceramide exposure.


CONCLUSIONS
Absence of survivin is incompatible with life. Although Jo2 induces expression of survivin, diminished baseline levels render the liver more sensitive to Fas, possibly due to functional effects on the mitochondria. This is the first in vivo documentation that survivin modulates caspase activation and that Fas-mediated hepatic apoptosis is regulated by survivin via mitochondrial pathways.
Conway
Edward M
EM
Center for Transgene Technology and Gene Therapy, Flanders Interuniversity Institute for Biotechnology, University of Leuven, Leuven, Belgium. ed.conway@med.kuleuven.ac.be
Pollefeyt
Saskia
S
Steiner-Mosonyi
Marta
M
Luo
Wei
W
Devriese
Astrid
A
Lupu
Florea
F
Bono
Francoise
F
Leducq
Nathalie
N
Dol
Frederique
F
Schaeffer
Paul
P
Collen
Désiré
D
Herbert
Jean-Marc
JM
D000818:Animals; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000502:physiology*; D003574:Cytochrome c Group / Q000378:metabolism; D020964:Embryo Loss / Q000209:etiology; D005260:Female; D022781:Hepatocytes / Q000378:metabolism; D051034:Inhibitor of Apoptosis Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins; D008928:Mitochondria / Q000502:physiology*; D009363:Neoplasm Proteins; D010085:Oxidative Phosphorylation; D011247:Pregnancy; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger / Q000032:analysis; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000077022:Survivin; D014158:Transcription, Genetic; D015854:Up-Regulation; D051028:bcl-2-Associated X Protein; D019014:fas Receptor / Q000502:physiology*
D051023:BH3 Interacting Domain Death Agonist Protein; C107489:BIRC5 protein, human; C494827:Bax protein, mouse; C494815:Bid protein, mouse; D002352:Carrier Proteins; D002868:Chromosomal Proteins, Non-Histone; D003574:Cytochrome c Group; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; C064769:N-acetylsphingosine; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D000077022:Survivin; D051028:bcl-2-Associated X Protein; D019014:fas Receptor; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D013110:Sphingosine