Parodi-Rullán Rebecca M, Chapa-Dubocq Xavier, Rullán Pedro J, Jang Sehwan, Javadov Sabzali
Department of Physiology, University of Puerto Rico School of Medicine, San JuanPR, United States.
Front Pharmacol. 2017 May 16;8:275. doi: 10.3389/fphar.2017.00275. eCollection 2017.
Sirtuins are NAD-dependent deacetylases that regulate cell metabolism through protein acetylation/deacetylation, and SIRT3 is the major deacetylase among mitochondrial isoforms. Here, we elucidated the possible role of acetylation of cyclophilin D, a key regulator of the mitochondrial permeability transition pore (mPTP), in mitochondria-mediated cardiac dysfunction induced by ischemia-reperfusion (IR) in wild type (WT) and SIRT3 knockout (SIRT3) mice. Isolated and Langendorff-mode perfused hearts of WT and SIRT3 mice were subjected to 25-min global ischemia followed by 60-min of reperfusion in the presence or absence of the mPTP inhibitor, sanglifehrin A (SfA). Analysis of mitochondrial sirtuins demonstrated that SIRT3 deficiency upregulated SIRT4 with no effect on SIRT5 expression. Hearts of SIRT3 mice exhibited significantly less recovery of cardiac function at the end of IR compared to WT mice. Intact (non-perfused) SIRT3 hearts exhibited an increased rate of Ca-induced swelling in mitochondria as an indicator of mPTP opening. However, there was no difference in mPTP opening and cyclophilin D acetylation between WT and SIRT3 hearts subjected to IR injury. Ca-stimulated HO production was significantly higher in SIRT3 mitochondria that was prevented by SfA. Superoxide dismutase activity was lower in SIRT3 heart mitochondria subjected to IR which correlated with an increase in protein carbonylation. However, mitochondrial DNA integrity was not affected in SIRT3 hearts after IR. SIRT3 deficiency exacerbates cardiac dysfunction during post-ischemic recovery, and increases mPTP opening and ROS generation without oxidative damage to mitochondrial proteins and DNA.
沉默调节蛋白是依赖烟酰胺腺嘌呤二核苷酸（NAD）的去乙酰化酶，通过蛋白质乙酰化/去乙酰化调节细胞代谢，而沉默调节蛋白3（SIRT3）是线粒体亚型中的主要去乙酰化酶。在此，我们阐明了亲环蛋白D（线粒体通透性转换孔（mPTP）的关键调节因子）乙酰化在野生型（WT）和SIRT3基因敲除（SIRT3）小鼠缺血再灌注（IR）诱导的线粒体介导的心脏功能障碍中的可能作用。分离并采用Langendorff模式灌注WT和SIRT3小鼠的心脏，在存在或不存在mPTP抑制剂桑吉瓦霉素A（SfA）的情况下，进行25分钟的全心缺血，随后再灌注60分钟。线粒体沉默调节蛋白分析表明，SIRT3缺乏上调了SIRT4，而对SIRT5表达无影响。与WT小鼠相比，SIRT3小鼠的心脏在IR结束时心脏功能的恢复明显较差。完整（未灌注）的SIRT3心脏线粒体中Ca2+诱导的肿胀率增加，作为mPTP开放的指标。然而，遭受IR损伤的WT和SIRT3心脏之间mPTP开放和亲环蛋白D乙酰化没有差异。Ca2+刺激的过氧化氢（HO）产生在SIRT3线粒体中显著更高，这被SfA所抑制。遭受IR的SIRT3心脏线粒体中超氧化物歧化酶活性较低，这与蛋白质羰基化增加相关。然而，IR后SIRT3心脏中线粒体DNA完整性未受影响。SIRT3缺乏加剧了缺血后恢复期间的心脏功能障碍，并增加了mPTP开放和活性氧生成，而不会对线粒体蛋白质和DNA造成氧化损伤。
