Castillo Elena C, Morales José A, Chapoy-Villanueva Héctor, Silva-Platas Christian, Treviño-Saldaña Niria, Guerrero-Beltrán C Enrique, Bernal-Ramírez Judith, Torres-Quintanilla Alejandro, García Noemí, Youker Keith, Torre-Amione Guillermo, García-Rivas Gerardo
Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Medicina Cardiovascular y Metabolómica, Monterrey, Mexico.
Tecnologico de Monterrey, Hospital Zambrano Hellion, TecSalud, Centro de Investigación Biomédica, San Pedro Garza García, Mexico.
Cell Physiol Biochem. 2019;53(3):465-479. doi: 10.33594/000000151.
BACKGROUND/AIMS: Cyclophilin D (CypD) mediates the mitochondrial permeability transition pore (mPTP) opening that contributes to mitochondrial dysfunction. CypD is regulated by its acetylation/deacetylation state that depends on Sirtuin-3 (SIRT3) mitochondrial deacetylase. Since obesity and metabolic syndrome decrease SIRT3 activity and expression, we tested the hypothesis that CypD hyperacetylation promotes mitochondrial dysfunction under this pathophysiological state, which is associated with ventricular dysfunction and heart failure.
Myocardial tissue samples from patients with left ventricular heart failure, with either obesity or normal weight, were processed for the expression of SIRT3 and acetylation profile by Western Blot (WB). In addition, a rat model of obesity and metabolic syndrome induced by 30% (w/v) of sucrose was conducted. The WB analysis was used to determine the levels of mitochondrial expression of SIRT3, Adenine Nucleotide Translocator (ANT), CypD and the acetylation profile, as well as immunoprecipitation to establish the acetylation levels of CypD. Mitochondrial function was assessed by oxygen consumption analysis and maximum Ca retention capacity. Oxidative stress was assessed by aconitase activity, protein carbonyl and thiol groups content.
SIRT3 expression in the biopsies of the failing human hearts showed a 46% decrease in the expression levels of obese patients in comparison to the non-obese patients (p=0.0219). Remarkably, body mass index was associated with protein acetylation (0.627; p = 0.035), suggesting that the acetylation profiles of the failing hearts of obese patients are partly mediated by a reduction in SIRT3, which is also associated with higher BNP levels, indicating a more severe ventricular dysfunction (-0.636; p = 0.043). Accordingly, obese rats demonstrated a SIRT3 mitochondrial expression decrease of 22% concomitantly with a hyperacetylated mitochondrial profile, including CypD. Cardiac mitochondria from obese animals were 2.5-fold more prone to mPTP opening than the controls.
Our results indicate that obesity reduces SIRT3 expression and that CypD hyperacetylation increases mPTP opening, suggesting that the activation of SIRT3 might be a potential target to decrease ventricular dysfunction and slow the progression of heart failure.
背景/目的：亲环素D（CypD）介导线粒体通透性转换孔（mPTP）开放，这会导致线粒体功能障碍。CypD受其乙酰化/去乙酰化状态调节，而该状态取决于线粒体去乙酰化酶沉默调节蛋白3（SIRT3）。由于肥胖和代谢综合征会降低SIRT3的活性和表达，我们检验了以下假设：在这种与心室功能障碍和心力衰竭相关的病理生理状态下，CypD的高乙酰化会促进线粒体功能障碍。
对肥胖或体重正常的左心室心力衰竭患者的心肌组织样本进行处理，通过蛋白质印迹法（WB）检测SIRT3的表达和乙酰化谱。此外，构建了由30%（w/v）蔗糖诱导的肥胖和代谢综合征大鼠模型。采用WB分析来确定SIRT3、腺嘌呤核苷酸转位酶（ANT）、CypD的线粒体表达水平和乙酰化谱，以及通过免疫沉淀法确定CypD的乙酰化水平。通过氧气消耗分析和最大钙保留能力评估线粒体功能。通过乌头酸酶活性、蛋白质羰基和巯基含量评估氧化应激。
与非肥胖患者相比，肥胖患者衰竭心脏活检组织中SIRT3的表达水平降低了46%（p = 0.0219）。值得注意的是，体重指数与蛋白质乙酰化相关（0.627；p = 0.035），这表明肥胖患者衰竭心脏的乙酰化谱部分是由SIRT3的减少介导的，这也与较高的脑钠肽水平相关，表明心室功能障碍更严重（-0.636；p = 0.043）。相应地，肥胖大鼠的SIRT3线粒体表达下降了22%，同时线粒体谱呈现高乙酰化，包括CypD。肥胖动物的心脏线粒体比对照组更容易发生mPTP开放2.5倍。
我们的结果表明，肥胖会降低SIRT3的表达，CypD的高乙酰化会增加mPTP开放，这表明激活SIRT3可能是减少心室功能障碍和减缓心力衰竭进展的潜在靶点。
