Regional myocardial ischemia-induced activation of MAPKs is associated with subcellular redistribution of caveolin and cholesterol.
Ischemia-reperfusion activates ERK and p38 MAPK in cardiac membranes, but the role of caveolae in MAPK signaling during this stress has not been studied. The purpose of this study was to determine the effect of in vivo myocardial ischemia-reperfusion on the level and distribution of caveolin-1 and -3 and cholesterol as well as MAPK activation in caveolin-enriched fractions. Adult male rats were subjected to in vivo regional myocardial ischemia induced by 25 min of coronary artery occlusion and 10 min (n = 5) or 2 h (n = 4) of reperfusion. Another group of rats served as appropriate nonischemic time controls (n = 4). A discontinuous sucrose density gradient was used to isolate caveolae/lipid rafts from ischemic and nonischemic heart tissue. Caveolin-1 and -3, as well as cholesterol, were enriched in the light fractions. A redistribution of caveolin-3 and a reduction in caveolin-1 and cholesterol levels in the light fractions occurred after 10 min of reperfusion. The ERKs were activated in ischemic zone light and heavy fractions by 10 min of reperfusion. p44 ERK was activated after 2 h of reperfusion only in the light fractions, whereas p42 ERK phosphorylation was increased in the light and heavy fractions. Although no p38 MAPK activation occurred after 10 min of reperfusion, 2 h of reperfusion caused significant activation of p38 MAPK in nonischemic zone light and heavy fractions. These results show the importance of caveolar membrane/lipid rafts in MAPK signaling and suggest that subcellular compartmentation of p44/p42 ERKs and p38 MAPK may play distinct roles in the response to myocardial ischemia-reperfusion.
Cardiothoracic Division, Department of Surgery, University of Kentucky, MN269 Chandler Medical Center, 800 Rose St., Lexington, KY 40536-0298, USA. ccrof2@uky.edu
Cherry
C
Ballard-Croft
Adam C
AC
Locklar
Gentian
G
Kristo
Robert D
RD
Lasley
D000818:Animals; D015153:Blotting, Western; D051242:Caveolin 1 / Q000378:metabolism*; D051244:Caveolin 3 / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D002784:Cholesterol / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017202:Myocardial Ischemia / Q000201:enzymology* / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000201:enzymology / Q000378:metabolism; D013395:Sucrose; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D051242:Caveolin 1; D051244:Caveolin 3; D007527:Isoenzymes; D013395:Sucrose; D002784:Cholesterol; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases