Departments of Medicine (Division of Cardiology), Virginia Commonwealth University, Richmond, VA, 23298, USA.
Departments of Medicine (Division of Cardiology), Virginia Commonwealth University, Richmond, VA, 23298, USA.
Free Radic Biol Med. 2020 Oct;158:162-170. doi: 10.1016/j.freeradbiomed.2020.06.006. Epub 2020 Jul 23.
p53 is a tumor suppressor protein with a very low content in the basal condition, but the content rapidly rises during stress conditions including ischemia-reperfusion. An increase in p53 content increases cardiac injury during ischemia-reperfusion. Since mitochondrial damage plays a key role in cardiac injury during ischemia-reperfusion, we asked if genetic ablation of p53 decreases cardiac injury by protecting mitochondria. Isolated, perfused hearts from cardiac specific p53 deletion or wild type underwent 25 min global ischemia at 37 °C and 60 min reperfusion. At the end of reperfusion, hearts were harvested for infarct size measurement. In separate groups, cardiac mitochondria were isolated at 30 min reperfusion. Time control hearts were buffer-perfused without ischemia. Compared to wild type, deletion of p53 improved cardiac functional recovery and decreased infarct size following ischemia-reperfusion. Oxidative phosphorylation was improved in p53 deletion mitochondria following ischemia-reperfusion compared to wild type. The net release of ROS generation from wild type but not in p53 deletion mitochondria was increased following ischemia-reperfusion. Peroxiredoxin 3 (PRDX 3) content was higher in p53 deletion than that in wild type, indicating that p53 deletion increases a key antioxidant. Ischemia-reperfusion led to increased spectrin cleavage (a marker of cytosolic calpain1 activation) in wild type but not in p53 deletion mice. Ischemia-reperfusion increased the truncation of mature AIF (apoptosis inducing factor, an indicator of mitochondrial calpain1 activation) in wild type but not in p53 deletion mice. The loss of cytochrome c from mitochondria was also decreased in p53 deletion following ischemia-reperfusion. Bcl-2 content was decreased in wild type but not in p53 deletion following reperfusion, suggesting that depletion of bcl-2 contributes to permeabilization of the mitochondrial outer membrane. Thus, deletion of p53 decreases cardiac injury by protecting mitochondria through attenuation of oxidative stress and calpain activation during ischemia-reperfusion.
p53 是一种肿瘤抑制蛋白，在基础状态下含量极低，但在包括缺血再灌注在内的应激条件下含量迅速升高。p53 含量的增加会增加缺血再灌注期间的心脏损伤。由于线粒体损伤在缺血再灌注期间的心脏损伤中起关键作用，我们询问了 p53 的基因缺失是否通过保护线粒体来减少心脏损伤。来自心脏特异性 p53 缺失或野生型的分离灌注心脏在 37°C 下经历 25 分钟的全局缺血和 60 分钟的再灌注。在再灌注结束时，收获心脏进行梗死面积测量。在单独的组中，在再灌注 30 分钟时分离心脏线粒体。时间对照心脏在没有缺血的情况下缓冲灌注。与野生型相比，p53 缺失可改善缺血再灌注后的心脏功能恢复并减少梗死面积。与野生型相比，缺血再灌注后 p53 缺失的线粒体氧化磷酸化得到改善。与野生型相比，缺血再灌注后从野生型但不是 p53 缺失线粒体中增加了 ROS 生成的净释放。与野生型相比，p53 缺失的过氧化物酶 3（PRDX 3）含量更高，表明 p53 缺失增加了一种关键的抗氧化剂。缺血再灌注导致野生型中裂体蛋白的切割增加（一种胞质钙蛋白酶 1 激活的标志物），但 p53 缺失小鼠中则没有。缺血再灌注增加了野生型中成熟 AIF 的截断（凋亡诱导因子，线粒体钙蛋白酶 1 激活的标志物），但 p53 缺失小鼠中则没有。缺血再灌注后，p53 缺失的细胞色素 c 从线粒体中的丢失也减少了。再灌注后野生型中 Bcl-2 含量减少，但 p53 缺失型中则没有，表明 bcl-2 的耗竭有助于线粒体外膜的通透性。因此，p53 的缺失通过在缺血再灌注期间减轻氧化应激和钙蛋白酶激活来保护线粒体，从而减少心脏损伤。
