Zinc prevents mitochondrial superoxide generation by inducing mitophagy in the setting of hypoxia/reoxygenation in cardiac cells
Zinc prevents mitochondrial superoxide generation by inducing mitophagy in the setting of hypoxia/reoxygenation in cardiac cells
复制标题
锌通过在心肌细胞缺氧/复氧的情况下诱导线粒体自噬来防止线粒体超氧化物的产生
DOI：
10.1080/10715762.2017.1414949
复制
发表时间：
2018-01-01
影响因子：
3.3
通讯作者：
Xu, Zhelong
中科院分区：
文献类型：
--
作者：
Bian, Xiyun;Teng, Tianming;Xu, Zhelong
摘要锌在自噬中起作用，保护心肌细胞免受缺血/再灌注损伤。本研究旨在检测在缺氧/复氧(H/R)状态下，锌是否能诱导线粒体吞噬作用，导致线粒体超氧化物歧化的抑制。H9c2细胞缺氧4 h，复氧2 h。在常氧条件下，用氯化锌处理细胞后，Lc3-II/Lc3-I比值和GFP-Lc3点均增加，表明锌诱导了自噬。进一步的实验表明，饥饿和雷帕霉素诱导的自噬需要内源性锌。锌可下调常氧细胞和缺氧再灌注细胞中TOM20、TIM23和COX4的表达，提示锌可触发细胞有丝分裂。在复氧过程中，锌可促进ERK活性和Beclin1的表达，PD98059和Beclin1 siRNA可抑制锌诱导的吞噬作用。PD98059可逆转锌诱导的Beclin1表达，提示锌通过ERK促进Beclin1的表达。此外，锌不能诱导转染PINK1 siRNA的细胞有丝分裂吞噬，并稳定线粒体中的PINK1。此外，PD98059可抑制锌诱导的PINK1的稳定作用。最后，锌阻止了线粒体在复氧时超氧化物的产生和线粒体膜电位(ΔΨm)的消散，这被Beclin1和PINK1siRNAs所阻断，这表明锌通过吞噬线粒体来防止线粒体氧化应激。综上所述，锌通过PINK1和Beclin1通过ERK诱导有丝分裂吞噬，从而在H/R损伤时阻止线粒体超氧化物的产生，清除受损的线粒体可能是锌对H/R损伤的心脏保护作用的原因。
Abstract Zinc plays a role in autophagy and protects cardiac cells from ischemia/reperfusion injury. This study aimed to test if zinc can induce mitophagy leading to attenuation of mitochondrial superoxide generation in the setting of hypoxia/reoxygenation (H/R) in cardiac cells. H9c2 cells were subjected to 4 h hypoxia followed by 2 h reoxygenation. Under normoxic conditions, treatments of cells with ZnCl2 increased both the LC3-II/LC3-I ratio and GFP-LC3 puncta, implying that zinc induces autophagy. Further experiments showed that endogenous zinc is required for the autophagy induced by starvation and rapamycin. Zinc down-regulated TOM20, TIM23, and COX4 both in normoxic cells and the cells subjected to H/R, indicating that zinc can trigger mitophagy. Zinc increased ERK activity and Beclin1 expression, and zinc-induced mitophagy was inhibited by PD98059 and Beclin1 siRNA during reoxygenation. Zinc-induced Beclin1 expression was reversed by PD98059, implying that zinc promotes Beclin1 expression via ERK. In addition, zinc failed to induce mitophagy in cells transfected with PINK1 siRNA and stabilized PINK1 in mitochondria. Moreover, zinc-induced PINK1 stabilization was inhibited by PD98059. Finally, zinc prevented mitochondrial superoxide generation and dissipation of mitochondrial membrane potential (ΔΨm) at reoxygenation, which was blocked by both the Beclin1 and PINK1 siRNAs, suggesting that zinc prevents mitochondrial oxidative stress through mitophagy. In summary, zinc induces mitophagy through PINK1 and Beclin1 via ERK leading to the prevention of mitochondrial superoxide generation in the setting of H/R. Clearance of damaged mitochondria may account for the cardioprotective effect of zinc on H/R injury.