内质网应激诱导的复合物 I 缺陷：钙超载的核心作用。
Endoplasmic reticulum stress-induced complex I defect: Central role of calcium overload.
机构信息
Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA, 23298, USA; Radiological Techniques Department, Health and Medical Technology College-Baghdad, Middle Technical University (MTU), Iraq.
Pauley Heart Center, Division of Cardiology, Department of Medicine, Virginia Commonwealth University, Richmond, VA, 23298, USA.
出版信息
Arch Biochem Biophys. 2020 Apr 15;683:108299. doi: 10.1016/j.abb.2020.108299. Epub 2020 Feb 12.
BACKGROUND
ER (endoplasmic reticulum) stress leads to decreased complex I activity in cardiac mitochondria. The aim of the current study is to explore the potential mechanisms by which ER stress leads to the complex I defect. ER stress contributes to intracellular calcium overload and oxidative stress that are two key factors to induce mitochondrial dysfunction. Since oxidative stress is often accompanied by intracellular calcium overload during ER stress in vivo, the role of oxidative stress and calcium overload in mitochondrial dysfunction was studied using in vitro models. ER stress results in intracellular calcium overload that favors activation of calcium-dependent calpains. The contribution of mitochondrial calpain activation in ER stress-mediated complex I damage was studied.
METHODS
Thapsigargin (THAP) was used to induce acute ER stress in H9c2 cells and C57BL/6 mice. Exogenous calcium (25 μM) and HO (100 μM) were used to induce modest calcium overload and oxidative stress in isolated mitochondria. Calpain small subunit 1 (CAPNS1) is essential to maintain calpain 1 and calpain 2 (CPN1/2) activities. Deletion of CAPNS1 eliminates the activities of CPN1/2. Wild type and cardiac-specific CAPNS1 deletion mice were used to explore the role of CPN1/2 activation in calcium-induced mitochondrial damage.
RESULTS
In isolated mitochondria, exogenous calcium but not HO treatment led to decreased oxidative phosphorylation, supporting that calcium overload contributes a key role in the mitochondrial damage. THAP treatment of H9c2 cells decreased respiration selectively with complex I substrates. THAP treatment activated cytosolic and mitochondrial CPN1/2 in C57BL/6 mice and led to degradation of complex I subunits including NDUFS7. Calcium treatment decreased NDUFS7 content in wild type but not in CAPNS1 knockout mice.
CONCLUSION
ER stress-mediated activation of mitochondria-localized CPN1/2 contributes to complex I damage by cleaving component subunits.
背景
内质网（ER）应激导致心脏线粒体中复合物 I 活性降低。本研究旨在探讨 ER 应激导致复合物 I 缺陷的潜在机制。ER 应激导致细胞内钙超载和氧化应激，这是诱导线粒体功能障碍的两个关键因素。由于 ER 应激过程中氧化应激通常伴随着细胞内钙超载，因此使用体外模型研究了氧化应激和钙超载在线粒体功能障碍中的作用。ER 应激导致细胞内钙超载，有利于钙依赖性钙蛋白酶的激活。研究了线粒体钙蛋白酶激活在 ER 应激介导的复合物 I 损伤中的作用。
方法
用他普西苷（THAP）诱导 H9c2 细胞和 C57BL/6 小鼠急性 ER 应激。用外源性钙（25 μM）和 HO（100 μM）诱导分离的线粒体中度钙超载和氧化应激。钙蛋白酶小亚基 1（CAPNS1）是维持钙蛋白酶 1 和钙蛋白酶 2（CPN1/2）活性所必需的。CAPNS1 的缺失消除了 CPN1/2 的活性。使用野生型和心脏特异性 CAPNS1 缺失小鼠来探讨 CPN1/2 激活在钙诱导的线粒体损伤中的作用。
结果
在分离的线粒体中，外源性钙而不是 HO 处理导致氧化磷酸化减少，支持钙超载在线粒体损伤中起关键作用。THAP 处理 H9c2 细胞选择性地降低呼吸作用，以复合物 I 为底物。THAP 处理激活了 C57BL/6 小鼠的胞质和线粒体 CPN1/2，并导致包括 NDUFS7 在内的复合物 I 亚基降解。钙处理降低了野生型小鼠的 NDUFS7 含量，但在 CAPNS1 敲除小鼠中没有降低。
结论
ER 应激介导的线粒体定位的 CPN1/2 的激活通过切割组成亚基导致复合物 I 损伤。
Zotero 插件