Department of Surgery, Indiana University School of Medicine, 950 W. Walnut Street, R2 E319, Indianapolis, IN, 46202, USA.
Electron Microscopy Center, Indiana University School of Medicine, Indianapolis, IN, USA.
Basic Res Cardiol. 2019 Nov 18;115(1):1. doi: 10.1007/s00395-019-0759-5.
Preserving mitochondrial activity is crucial in rescuing cardiac function following acute myocardial ischemia/reperfusion (I/R). The sex difference in myocardial functional recovery has been observed after I/R. Given the key role of mitochondrial connexin43 (Cx43) in cardiac protection initiated by ischemic preconditioning, we aimed to determine the implication of mitochondrial Cx43 in sex-related myocardial responses and to examine the effect of estrogen (17β-estradiol, E2) on Cx43, particularly mitochondrial Cx43-involved cardiac protection following I/R. Mouse primary cardiomyocytes and isolated mouse hearts (from males, females, ovariectomized females, and doxycycline-inducible Tnnt2-controlled Cx43 knockout without or with acute post-ischemic E2 treatment) were subjected to simulated I/R in culture or Langendorff I/R (25-min warm ischemia/40-min reperfusion), respectively. Mitochondrial membrane potential and mitochondrial superoxide production were measured in cardiomyocytes. Myocardial function and infarct size were determined. Cx43 and its isoform, Gja1-20k, were assessed in mitochondria. Immunoelectron microscopy and co-immunoprecipitation were also used to examine mitochondrial Cx43 and its interaction with estrogen receptor-α by E2 in mitochondria, respectively. There were sex disparities in stress-induced cardiomyocyte mitochondrial function. E2 partially restored mitochondrial activity in cardiomyocytes following acute injury. Post-ischemia infusion of E2 improved functional recovery and reduced infarct size with increased Cx43 content and phosphorylation in mitochondria. Ablation of cardiac Cx43 aggravated mitochondrial damage and abolished E2-mediated cardiac protection during I/R. Female mice were more resistant to myocardial I/R than age-matched males with greater protective role of mitochondrial Cx43 in female hearts. Post-ischemic E2 usage augmented mitochondrial Cx43 content and phosphorylation, increased mitochondrial Gja1-20k, and showed cardiac protection.
在急性心肌缺血/再灌注（I/R）后，维持线粒体活性对于挽救心脏功能至关重要。已经观察到 I/R 后心肌功能恢复存在性别差异。鉴于线粒体连接蛋白 43（Cx43）在心梗预处理引发的心脏保护中发挥关键作用，我们旨在确定线粒体 Cx43 在性别相关心肌反应中的意义，并研究雌激素（17β-雌二醇，E2）对 Cx43 的影响，特别是在 I/R 后，E2 对涉及线粒体 Cx43 的心脏保护作用。我们将原代心肌细胞和分离的鼠心（来自雄性、雌性、卵巢切除雌性和可诱导 Tnnt2 控制 Cx43 敲除的鼠心，这些鼠心没有或急性缺血后接受 E2 处理）分别置于培养物中的模拟 I/R 或 Langendorff I/R 中（25 分钟的热缺血/40 分钟的再灌注）。在心肌细胞中测量线粒体膜电位和线粒体超氧化物产生。测定心肌功能和梗死面积。评估线粒体中的 Cx43 及其同工型 Gja1-20k。免疫电镜和共免疫沉淀也分别用于检测线粒体 Cx43 及其与雌激素受体-α的相互作用。在应激诱导的心肌细胞线粒体功能方面存在性别差异。E2 部分恢复了急性损伤后心肌细胞中的线粒体活性。缺血后输注 E2 改善了功能恢复，减少了梗死面积，同时增加了线粒体中的 Cx43 含量和磷酸化。心脏 Cx43 的缺失加剧了线粒体损伤，并消除了 E2 在 I/R 期间的心脏保护作用。雌性小鼠比同龄雄性小鼠对心肌 I/R 的抵抗力更强，线粒体 Cx43 在雌性心脏中发挥更大的保护作用。缺血后使用 E2 增加了线粒体 Cx43 的含量和磷酸化，增加了线粒体 Gja1-20k，并显示出心脏保护作用。
