Myeloperoxidase-derived oxidants inhibit sarco/endoplasmic reticulum Ca2+-ATPase activity and perturb Ca2+ homeostasis in human coronary artery endothelial cells
Myeloperoxidase-derived oxidants inhibit sarco/endoplasmic reticulum Ca2+-ATPase activity and perturb Ca2+ homeostasis in human coronary artery endothelial cells
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DOI：
10.1016/j.freeradbiomed.2011.12.001
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发表时间：
2012-03-01
影响因子：
7.4
通讯作者：
Davies, Michael J.
中科院分区：
文献类型：
--
作者：
Cook, Naomi L.;Viola, Helena M.;Davies, Michael J.
肌浆网/内质网Ca ~（2+）-ATP酶（SERCA）通过在肌浆网/内质网中螯合Ca ~（2+）在Ca ~（2+）稳态中起关键作用。这种泵的活性受到氧化剂的抑制，并在老化组织和心血管疾病中受损。我们以前已经表明，髓过氧化物酶（MPO）衍生的氧化剂HOG和HOSCN的目标硫醇和介导的细胞功能障碍。由于SERCA含有对ATP酶活性至关重要的Cys残基，我们假设HOCl和HOSCN可能通过巯基氧化抑制SERCA活性，并增加人冠状动脉内皮细胞（HCAEC）中的胞质Ca 2+水平。暴露于预先形成或酶促产生的HOCl和HOSCN的肌浆网囊泡导致ATP酶活性的浓度依赖性降低，这也被抑制SERCA抑制剂毒胡萝卜素。分解HOSCN和不完整的MPO酶系统没有降低活性。ATP酶活性的丧失与SERCA Cys残基的氧化和蛋白质修饰同时发生。暴露的HCAEC，有或没有外部Ca 2+，HOSCN或HOCl导致细胞内Ca 2+的时间和浓度依赖性增加的条件下，不导致细胞活力的立即损失。毒胡萝卜素，但不是质膜或线粒体Ca 2+泵/通道的抑制剂，完全减弱了细胞内Ca 2+的增加，这与SERCA在维持内皮细胞Ca 2+稳态中的关键作用一致。血管紧张素II预处理增强了低浓度HOSCN的作用。MPO介导的细胞内Ca 2+水平的调节可能会加剧内皮功能障碍，这是动脉粥样硬化的关键早期事件，并且在吸烟者中更为明显，因为他们的SCN-水平较高。(C)2011 Elsevier Inc. All rights reserved.
The sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) plays a critical role in Ca2+ homeostasis via sequestration of this ion in the sarco/endoplasmic reticulum. The activity of this pump is inhibited by oxidants and impaired in aging tissues and cardiovascular disease. We have shown previously that the myeloperoxidase (MPO)-derived oxidants HOG and HOSCN target thiols and mediate cellular dysfunction. As SERCA contains Cys residues critical to ATPase activity, we hypothesized that HOCl and HOSCN might inhibit SERCA activity, via thiol oxidation, and increase cytosolic Ca2+ levels in human coronary artery endothelial cells (HCAEC). Exposure of sarcoplasmic reticulum vesicles to preformed or enzymatically generated HOCl and HOSCN resulted in a concentration-dependent decrease in ATPase activity; this was also inhibited by the SERCA inhibitor thapsigargin. Decomposed HOSCN and incomplete MPO enzyme systems did not decrease activity. Loss of ATPase activity occurred concurrent with oxidation of SERCA Cys residues and protein modification. Exposure of HCAEC, with or without external Ca2+, to HOSCN or HOCl resulted in a time- and concentration-dependent increase in intracellular Ca2+ under conditions that did not result in immediate loss of cell viability. Thapsigargin, but not inhibitors of plasma membrane or mitochondrial Ca2+ pumps/channels, completely attenuated the increase in intracellular Ca2+ consistent with a critical role for SERCA in maintaining endothelial cell Ca2+ homeostasis. Angiotensin II pretreatment potentiated the effect of HOSCN at low concentrations. MPO-mediated modulation of intracellular Ca2+ levels may exacerbate endothelial dysfunction, a key early event in atherosclerosis, and be more marked in smokers because of their higher SCN- levels. (C) 2011 Elsevier Inc. All rights reserved.