Neuroscience Graduate Program, Vanderbilt University, Nashville, Tennessee 37232-8548, USA.
Antioxid Redox Signal. 2011 May 15;14(10):1787-801. doi: 10.1089/ars.2010.3300. Epub 2010 Dec 2.
The decision to remove or refold oxidized, denatured, or misfolded proteins by heat shock protein 70 and its binding partners is critical to determine cell fate under pathophysiological conditions. Overexpression of the ubiquitin ligase C-terminus of HSC70 interacting protein (CHIP) can compensate for failure of other ubiquitin ligases and enhance protein turnover and survival under chronic neurological stress. The ability of CHIP to alter cell fate after acute neurological injury has not been assessed. Using postmortem human tissue samples, we provide the first evidence that cortical CHIP expression is increased after ischemic stroke. Oxygen glucose deprivation in vitro led to rapid protein oxidation, antioxidant depletion, proteasome dysfunction, and a significant increase in CHIP expression. To determine if CHIP upregulation enhances neural survival, we overexpressed CHIP in vitro and evaluated cell fate 24 h after acute oxidative stress. Surprisingly, CHIP overexpressing cells fared worse against oxidative injury, accumulated more ubiquitinated and oxidized proteins, and experienced decreased proteasome activity. Conversely, using small interfering RNA to decrease CHIP expression in primary neuronal cultures improved survival after oxidative stress, suggesting that increases in CHIP observed after stroke like injuries are likely correlated with diminished survival and may negatively impact the neuroprotective potential of heat shock protein 70.
热休克蛋白 70 及其结合伴侣对氧化、变性或错误折叠蛋白质的去除或重折叠的决定,对于在病理生理条件下决定细胞命运至关重要。泛素连接酶 C 末端的 HSC70 相互作用蛋白 (CHIP) 的过表达可以补偿其他泛素连接酶的失效,并在慢性神经应激下增强蛋白质周转和存活。CHIP 在急性神经损伤后改变细胞命运的能力尚未得到评估。使用死后人体组织样本,我们首次提供证据表明,皮质 CHIP 表达在缺血性中风后增加。体外氧葡萄糖剥夺导致蛋白质快速氧化、抗氧化剂耗竭、蛋白酶体功能障碍和 CHIP 表达显著增加。为了确定 CHIP 的上调是否增强神经存活,我们在体外过表达 CHIP 并在急性氧化应激后 24 小时评估细胞命运。令人惊讶的是,CHIP 过表达细胞在氧化损伤下的情况更糟,积累了更多的泛素化和氧化蛋白,并经历了蛋白酶体活性的降低。相反,在原代神经元培养物中使用小干扰 RNA 降低 CHIP 表达可改善氧化应激后的存活,表明中风样损伤后观察到的 CHIP 增加可能与存活减少相关,并可能对热休克蛋白 70 的神经保护潜力产生负面影响。