Abstract Myocardial zinc dyshomeostasis is associated with caspase-3 activation, ErbB2 degradation and apoptosis during hypoxia/reoxygenation. Zinc pyrithione replenishes intracellular zinc, suppresses caspase-3, augments ErbB2 levels and improves cell survival. We hypothesize that zinc is capable of modulating redox and endoplasmic reticulum (ER) stress in the setting of cardiomyocyte hypoxia-reoxygenation. Hypoxia/reoxygenation lowered intracellular zinc, increased ER as well as oxidative stress in H9c2 cells, both of which were effectively attenuated by zinc supplementation. Silencing of gp91phox attenuated oxidative and ER stress, decreased caspase-3 activation and improved cell survival. Mimicking the oxidative insult using 50 μM H2O2 increased the caspase-3 activity that correlated with decreased ErbB2 levels, concomitant with augmented ER stress. N-acetyl cysteine (NAC) administration completely suppressed ER stress as well as caspase-3 activity. Zinc depletion using TPEN also resulted in lowered ErbB2 and increased apoptosis, along with NOX2 mRNA upregulation, increased oxidative and ER stress. Repletion with zinc suppressed NOX2 mRNA, lowered oxidative as well as ER stress and decreased cell death. These results suggest that zinc dyshomeostasis, along with oxidative stress contribute to the unfolded protein response during myocardial H/R and that zinc replenishment corrects zinc homeostasis, alleviates associated stress and improves cardiomyocyte survival.

中文翻译：

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心肌细胞缺氧/复氧期间氧化和内质网应激的锌依赖性变化

摘要 心肌锌稳态失调与缺氧/复氧期间 caspase-3 激活、ErbB2 降解和细胞凋亡有关。吡啶硫酮锌补充细胞内锌，抑制 caspase-3，增加 ErbB2 水平并提高细胞存活率。我们假设锌能够在心肌细胞缺氧-复氧的情况下调节氧化还原和内质网 (ER) 应激。缺氧/复氧降低了细胞内锌，增加了 H9c2 细胞中的 ER 和氧化应激，这两者都被锌补充剂有效减弱。gp91phox 的沉默减弱了氧化和内质网应激，降低了 caspase-3 的激活并提高了细胞存活率。使用 50 μM H2O2 模拟氧化损伤增加了与 ErbB2 水平降低相关的 caspase-3 活性，伴随着增加的 ER 压力。N-乙酰半胱氨酸 (NAC) 给药完全抑制了内质网应激以及 caspase-3 活性。使用 TPEN 的锌耗竭还导致 ErbB2 降低和细胞凋亡增加，同时 NOX2 mRNA 上调、氧化和内质网应激增加。补充锌可抑制 NOX2 mRNA，降低氧化和内质网应激并减少细胞死亡。这些结果表明，锌稳态失调以及氧化应激有助于心肌 H/R 期间未折叠蛋白反应，补锌可纠正锌稳态，减轻相关压力并提高心肌细胞存活率。随着 NOX2 mRNA 上调，氧化和内质网应激增加。补充锌可抑制 NOX2 mRNA，降低氧化和内质网应激并减少细胞死亡。这些结果表明，锌稳态失调以及氧化应激有助于心肌 H/R 期间未折叠蛋白反应，补锌可纠正锌稳态，减轻相关压力并提高心肌细胞存活率。随着 NOX2 mRNA 上调，氧化和内质网应激增加。补充锌可抑制 NOX2 mRNA，降低氧化和内质网应激并减少细胞死亡。这些结果表明，锌稳态失调以及氧化应激有助于心肌 H/R 期间未折叠蛋白反应，补锌可纠正锌稳态，减轻相关压力并提高心肌细胞存活率。