Genetically induced moderate inhibition of the proteasome in cardiomyocytes exacerbates myocardial ischemia-reperfusion injury in mice.
Genetically induced moderate inhibition of the proteasome in cardiomyocytes exacerbates myocardial ischemia-reperfusion injury in mice.
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DOI：
10.1161/circresaha.112.270983
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发表时间：
2012-08-17
影响因子：
20.1
通讯作者：
Wang X
中科院分区：
文献类型：
--
作者：
Tian Z;Zheng H;Li J;Li Y;Su H;Wang X
心肌细胞限制性蛋白酶体功能增强和药理学蛋白酶体抑制（PSMI）被证明可以减轻心肌缺血/再灌注（I/R）损伤。心肌蛋白酶体功能障碍在I/R过程中的作用以及通过操纵蛋白酶体功能来减少I/R损伤的前景仍不清楚。我们试图确定I/R心脏中蛋白酶体的充足性，建立心肌细胞限制性PSMI（CR-PSMI）的小鼠模型，并测试CR-PSMI对I/R损伤的影响。通过结扎（30分钟）和随后释放过表达GFPdgn（一种经验证的替代蛋白酶体底物）的小鼠的左前降支动脉来模拟心肌I/R。在再灌注24小时，心肌蛋白酶体活性显着降低，而总泛素结合物和GFPdgn蛋白水平显着高于所有地区的I/R心脏比假对照组，表明蛋白酶体功能不全。完整小鼠中的CR-PSMI是通过由减毒小鼠mhc 6启动子驱动的肽酶失活小鼠β5亚基（T60 A-β5）的转基因（tg）过表达实现的。过表达的T60 A-β5可以替代内源性β5并抑制心脏中的蛋白酶体糜蛋白酶样活性。中度CR-PSMI的小鼠在基线时没有显示异常，但与非tg同窝小鼠相比，在I/R期间显示出明显更明显的结构和功能损伤。中度CR-PSMI加重I/R损伤与PTEN和蛋白激酶Cδ（PKCδ）蛋白水平显著升高、Akt活化降低和PKCε降低相关。心肌I/R导致心肌细胞蛋白酶体功能不全，中度CR-PSMI可增强PTEN和PKCδ，抑制Akt和PKCε，增加心肌细胞凋亡，减轻I/R损伤。
Both cardiomyocyte-restricted proteasome functional enhancement and pharmacological proteasome inhibition (PSMI) were shown to attenuate myocardial ischemia/reperfusion (I/R) injury. The role of cardiac proteasome dysfunction during I/R and the perspective to diminish I/R injury by manipulating proteasome function remain unclear. We sought to determine proteasome adequacy in I/R hearts, create a mouse model of cardiomyocyte-restricted PSMI (CR-PSMI), and test CR-PSMI impact on I/R injury. Myocardial I/R were modeled by ligation (30min) and subsequent release of the left anterior descending artery in mice overexpressing GFPdgn, a validated surrogate proteasome substrate. At 24h of reperfusion, myocardial proteasome activities were significantly lower while total ubiquitin conjugates and GFPdgn protein levels were markedly higher in all regions of the I/R hearts than the sham controls, indicative of proteasome functional insufficiency. CR-PSMI in intact mice was achieved by transgenic (tg) overexpression of a peptidase-disabled mouse β5 subunit (T60A-β5) driven by an attenuated mouse mhc6 promoter. Overexpressed T60A-β5 can replace endogenous β5 and inhibits proteasome chymotrypsin-like activities in the heart. Mice with moderate CR-PSMI showed no abnormalities at the baseline but displayed markedly more pronounced structural and functional damage during I/R, compared with non-tg littermates. The exacerbation of I/R injury by moderate CR-PSMI was associated with significant increases in the protein level of PTEN and protein kinase Cδ (PKCδ), decreased Akt activation, and reduced PKCε. Myocardial I/R causes proteasome functional insufficiency in cardiomyocytes and moderate CR-PSMI augments PTEN and PKCδ, suppresses Akt and PKCε, increases cardiomyocyte apoptosis, and aggravates I/R injury in mice.