Akt activation protects rat liver from ischemia/reperfusion injury.
BACKGROUND
Apoptosis as well as necrosis may play an important role in hepatic ischemia/reperfusion (I/R) injury. Akt, a serine-threonine protein kinase, is known to promote cell survival. We investigated whether gene transfer of constitutively active or dominant negative Akt could affect hepatic I/R injury.


METHODS
Hepatic I/R injury was induced in rats by Pringle's maneuver for 20 min followed by reperfusion. Adenoviruses encoding a constitutively active form of Akt (myrAkt), a dominant negative form of Akt (dnAkt), or beta-galactosidase (LacZ) were injected through the tail vein 72 h before hepatic I/R.


RESULTS
Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) staining demonstrated a significant increase in the positive cells 240 min after reperfusion. Immunoblotting with phospho-Akt antibody showed phosphorylation of Akt from 90 to 180 min after reperfusion. The expression of myrAkt reduced the number of TUNEL-positive cells and hepatic necrosis around the central veins in the liver after reperfusion. This expression also significantly inhibited the increase in serum alanine aminotransferase (297 +/- 131 IU/L, P < 0.05) 120 min after I/R, compared with increases in uninfected (1761 +/- 671 IU/L), LacZ adenovirus (1528 +/- 671 IU/L)-, and dnAkt adenovirus (1342 +/- 485 IU/L)-infected rats. MyrAkt expression phosphorylated Bad and inhibited the release of cytochrome-c after reperfusion. No difference in nuclear translocation of nuclear factor (NF)-kappaB, p65 was seen among the three groups of rats, however.


CONCLUSIONS
Adenoviral gene transfer of myrAkt could inhibit apoptotic cell death and subsequent hepatic I/R injury in the rat, through Bad, not NF-kappaB.
Harada
Nobuko
N
Department of Gastroenterological Surgery, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Hatano
Etsuro
E
Koizumi
Naoki
N
Nitta
Takashi
T
Yoshida
Masanori
M
Yamamoto
Naritaka
N
Brenner
David A
DA
Yamaoka
Yoshio
Y
D000256:Adenoviridae / Q000235:genetics; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D045304:Cytochromes c / Q000037:antagonists & inhibitors; D003593:Cytoplasm / Q000378:metabolism; D018014:Gene Transfer Techniques; D015151:Immunoblotting; D020287:In Situ Nick-End Labeling; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008102:Liver Circulation; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control*; D051025:bcl-Associated Death Protein
D051023:BH3 Interacting Domain Death Agonist Protein; C494821:Bad protein, rat; C494816:Bid protein, rat; D002352:Carrier Proteins; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D051025:bcl-Associated Death Protein; D045304:Cytochromes c; D000410:Alanine Transaminase; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt