Essential role of lipid raft in ischemic preconditioning.
Lipid rafts represent a subcompartment of the plasma membrane that coordinate and regulate varieties of signaling processes while caveolins are the integral membrane protein of the lipid raft. To study the role of lipid raft in ischemic preconditioning (PC) of the heart, rat hearts were perfused by working mode and then preconditioned in absence or presence of a lipid raft disintegrator, Methyl-beta-cyclodextrin. As expected, precondition made the heart resistant to ischemia reperfusion (I/R) injury as evident by improved ventricular performance, reduced myocardial infract size and cardiomyocyte apoptosis. Cyclodextrin abolished the cardioprotection. Transmission Electron Microscopy revealed severe degeneration, swelling of mitochondria, chromatin condensation and myofibril disarray in cyclodextrin treated PC heart similar to I/R heart. In the PC hearts, there was an increased association of the proapoptotic p38MAPKalpha with caveolin-1 while there was a reduced association of anti-apoptotic p38MAPKbeta with caveolin-3 indicating that reduced amount of p38MAPKalpha and increased amount of p38MAPKbeta were available to the adapted hearts thereby generating a survival signal. In contrast, there was very weak caveolin-MAP kinase interaction in cyclodextrin treated heart. Myocardial damage was further confirmed by reduced or no expression of anti-apoptotic phospho-AKT, Bcl2, Bcl-xl and increased expression of pro-apoptotic JNK, BAX, and p53 in methyl-beta-cyclodextrin (lipid raft disintegrator) treated heart. These results indicate that lipid raft play a pivotal role in the generation of survival signal in PC or adapted heart and disintegration of lipid raft completely abolish cardioprotection.
Das
Manika
M
Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, CT, USA.
Gherghiceanu
Mihaela
M
Lekli
Istvan
I
Mukherjee
Subhendu
S
Popescu
Lawrence M
LM
Das
Dipak K
DK
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051242:Caveolin 1 / Q000378:metabolism; D051244:Caveolin 3 / Q000378:metabolism; D003505:Cyclodextrins / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley
D051242:Caveolin 1; D051244:Caveolin 3; D003505:Cyclodextrins; D020928:Mitogen-Activated Protein Kinases