The influence of phosphatidylinositol 3-kinase/Akt pathway on the ischemic injury during rat liver graft preservation.
We aimed to investigate the role of phosphatidylinositol 3 (PI3)-kinase/Akt pathway on ischemic injury. Rat liver grafts were preserved in UW solution with different treatments and were compared by 1-week survival rates and morphological changes with those of the control group. PI3-kinase/Akt was significantly activated at the sites of Thr 308 and Ser 473 in the preserved grafts. Downstream target proteins, glycogen synthase kinase-3beta (GSK-3beta) and caspase-9, were inactivated. However, survival signal transduction from Akt to Bad was blocked by calcium release after activation of PI3-kinase/Akt. Significant activation of caspase-12, -3 and -7 contributed to cell apoptosis and severe ischemic injury was shown after 7 h of preservation by UW solution with insulin. Downregulation of phospho-Akt at Thr 308 and Ser 473 was due to partial inhibition of PI3-kinase/Akt pathway by LY294002. Activation of GSK-3beta and inactivation of caspase-12 and Bad could be found in the LY294002 groups in which the liver grafts showed less ischemic injury. Higher 1-week survival rates in the heparin, LY294002, and glucagon groups confirmed the dysregulation of the pathway. In conclusion, PI3-kinase/Akt pathway was dysregulated and contributed to ischemic injury during preservation. Heparin and LY294002 could improve graft viability by maintaining calcium homeostasis during preservation.
Li
Xian Liang
XL
Centre for the Study of Liver Disease and Department of Surgery, The University of Hong Kong, Pokfulam, Republic of China. lix1@graduate.hku.hk
Man
Kwan
K
Ng
Kevin T
KT
Sun
Chris K
CK
Lo
Chung Mau
CM
Fan
Sheung Tat
ST
D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006085:Graft Survival; D007511:Ischemia / Q000378:metabolism* / Q000473:pathology; D016031:Liver Transplantation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D011917:Rats, Inbred Lew; D015427:Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction; D051025:bcl-Associated Death Protein
D002118:Calcium; D002352:Carrier Proteins; D020169:Caspases; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D051025:bcl-Associated Death Protein; C494821:Bad protein, rat; C494920:Akt1 protein, rat; C000605508:Gsk3b protein, rat