Burn and Shock Trauma Institute, Department of Surgery, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, USA.
Biochem Biophys Res Commun. 2010 Oct 29;401(4):548-53. doi: 10.1016/j.bbrc.2010.09.093. Epub 2010 Sep 26.
Recently, we provided evidence for a possible role of the cardiac proteasome during ischemia, suggesting that a subset of 26S proteasomes is a cell-destructive protease, which is activated as the cellular energy supply declines. Although proteasome inhibition during cold ischemia (CI) reduced injury of ischemic hearts, it remains unknown whether these beneficial effects are maintained throughout reperfusion, and thus, may have pathophysiological relevance. Therefore, we evaluated the effects of epoxomicin (specific proteasome inhibitor) in a rat heterotopic heart transplantation model. Donor hearts were arrested with University of Wisconsin solution (UW) and stored for 12 h/24 h in 4 °C UW±epoxomicin, followed by transplantation. Efficacy of epoxomicin was confirmed by proteasome peptidase activity measurements and analyses of myocardial ubiquitin pools. After 12hCI, troponin I content of UW was lower with epoxomicin. Although all hearts after 12hCI started beating spontaneously, addition of epoxomicin to UW during CI reduced cardiac edema and preserved the ultrastructural integrity of the post-ischemic cardiomyocyte. After 24hCI in UW±epoxomicin, hearts did not regain contractility. When hearts were perfused with epoxomicin during cardioplegia, the cardiac proteasome was inhibited immediately, all of these hearts started beating after 24hCI in UW plus epoxomicin and cardiac edema and myocardial ultrastructure were comparable to hearts after 12hCI. Epoxomicin did not affect markers of lipid peroxidation or neutrophil infiltration in post-ischemic hearts. These data further support the concept that proteasome activation during ischemia is of pathophysiological relevance and suggest proteasome inhibition as a promising approach to improve organ preservation strategies.
最近，我们提供了心脏蛋白酶体在缺血过程中可能发挥作用的证据，表明 26S 蛋白酶体的一部分是一种细胞破坏性蛋白酶，当细胞能量供应下降时被激活。虽然冷缺血期间（CI）的蛋白酶体抑制减少了缺血心脏的损伤，但尚不清楚这些有益作用是否在再灌注期间得以维持，因此，可能具有病理生理学相关性。因此，我们在大鼠异位心脏移植模型中评估了环氧酶抑制剂（特异性蛋白酶体抑制剂）的作用。供心用威斯康星大学溶液（UW）停搏，在 4°C UW±环氧酶抑制剂中储存 12 h/24 h，然后进行移植。通过蛋白酶体肽酶活性测量和心肌泛素池分析来确认环氧酶抑制剂的功效。在 12hCI 后，UW 中的肌钙蛋白 I 含量较低。虽然所有在 12hCI 后开始自动跳动的心脏，但在 CI 期间将环氧酶抑制剂添加到 UW 中可减少心脏水肿并保持缺血后心肌细胞的超微结构完整性。在 UW±环氧酶抑制剂中进行 24hCI 后，心脏没有恢复收缩性。当心脏在用环氧酶抑制剂进行心脏停搏期间进行灌流时，心脏蛋白酶体立即被抑制，所有这些心脏在 UW 加环氧酶抑制剂后 24hCI 后开始跳动，心脏水肿和心肌超微结构与 12hCI 后的心脏相当。环氧酶抑制剂对缺血后心脏的脂质过氧化或中性粒细胞浸润标志物没有影响。这些数据进一步支持了这样的概念，即缺血过程中蛋白酶体的激活具有病理生理学相关性，并表明蛋白酶体抑制是改善器官保存策略的一种有前途的方法。
