Wang Lei, Li Xiaona, Chen Lili, Mei Shenglan, Shen Qianni, Liu Lian, Liu Xuke, Liao Shichong, Zhao Bo, Chen Yannan, Hou Jiabao
Department of Neurosurgery, Renmin Hospital of Wuhan University, Wuhan, 430060, China.
Department of Pain Medicine, Wuhan Fourth Hospital, Wuhan, 430033, China.
Mol Neurobiol. 2025 Jan;62(1):501-517. doi: 10.1007/s12035-024-04288-0. Epub 2024 Jun 14.
Ischemic stroke is a devastating disease in which mitochondrial damage or dysfunction substantially contributes to brain injury. Mitochondrial uncoupling protein-2 (UCP2) is a member of the UCP family, which regulates production of mitochondrial superoxide anion. UCP2 is reported to be neuroprotective for ischemic stroke-induced brain injury. However, the molecular mechanisms of UCP2 in ischemic stroke remain incompletely understood. In this study, we investigated whether and how UCP2 modulates neuroinflammation and regulates neuronal ferroptosis following ischemic stroke in vitro and in vivo. Wild-type (WT) and UCP2 knockout (Ucp2) mice were subjected to middle cerebral artery occlusion (MCAO). BV2 cells (mouse microglial cell line) and HT-22 cells (mouse hippocampal neuronal cell line) were transfected with small interfering (si)-RNA or overexpression plasmids to knockdown or overexpress UCP2 levels. Cells were then exposed to oxygen-glucose deprivation and reoxygenation (OGD/RX) to simulate hypoxic injury in vitro. We found that UCP2 expression was markedly reduced in a time-dependent manner in both in vitro and in vivo ischemic stroke models. In addition, UCP2 was mainly expressed in neurons. UCP2 deficiency significantly enlarged infarct volumes, aggravated neurological deficit scores, and exacerbated cerebral edema in mice after MCAO. In vitro knockdown of Ucp2 and in vivo genetic depletion of Ucp2 (Ucp2 mice) increased neuronal ferroptosis-related indicators, including Fe, malondialdehyde, glutathione, and lipid peroxidation. Overexpression of UCP2 in neuronal cells resulted in reduced ferroptosis. Moreover, knockdown of UCP2 exacerbated neuroinflammation in BV2 microglia and mouse ischemic stroke models, suggesting that endogenous UCP2 inhibits neuroinflammation following ischemic stroke. Upregulation of UCP2 expression in microglia appeared to decrease the release of pro-inflammatory factors and increase the levels of anti-inflammatory factors. Further investigation showed that UCP2 deletion inhibited expression of AMPKα/NRF1 pathway-related proteins, including p-AMPKα, t-AMPKα, NRF1, and TFAM. Thus, UCP2 protects the brain from ischemia-induced ferroptosis by activating AMPKα/NRF1 signaling. Activation of UCP2 represents an attractive strategy for the prevention and treatment of ischemic stroke.
缺血性中风是一种毁灭性疾病，其中线粒体损伤或功能障碍在很大程度上导致脑损伤。线粒体解偶联蛋白2（UCP2）是UCP家族的成员，可调节线粒体超氧阴离子的产生。据报道，UCP2对缺血性中风诱导的脑损伤具有神经保护作用。然而，UCP2在缺血性中风中的分子机制仍不完全清楚。在本研究中，我们在体外和体内研究了UCP2是否以及如何调节神经炎症并在缺血性中风后调节神经元铁死亡。野生型（WT）和UCP2基因敲除（Ucp2）小鼠接受大脑中动脉闭塞（MCAO）。用小干扰（si）RNA或过表达质粒转染BV2细胞（小鼠小胶质细胞系）和HT-22细胞（小鼠海马神经元细胞系）以降低或过表达UCP2水平。然后将细胞暴露于氧葡萄糖剥夺和复氧（OGD/RX）以模拟体外缺氧损伤。我们发现在体外和体内缺血性中风模型中，UCP2表达均以时间依赖性方式显著降低。此外，UCP2主要在神经元中表达。UCP2缺乏显著扩大了MCAO后小鼠的梗死体积，加重了神经功能缺损评分，并加剧了脑水肿。体外敲低Ucp2和体内Ucp2基因缺失（Ucp2小鼠）增加了神经元铁死亡相关指标，包括铁、丙二醛、谷胱甘肽和脂质过氧化。神经元细胞中UCP2的过表达导致铁死亡减少。此外，敲低UCP2加剧了BV2小胶质细胞和小鼠缺血性中风模型中的神经炎症，表明内源性UCP2抑制缺血性中风后的神经炎症。小胶质细胞中UCP2表达的上调似乎减少了促炎因子的释放并增加了抗炎因子的水平。进一步研究表明，UCP2缺失抑制了AMPKα/NRF1途径相关蛋白的表达，包括p-AMPKα、t-AMPKα、NRF1和TFAM。因此，UCP2通过激活AMPKα/NRF1信号保护大脑免受缺血诱导 的铁死亡。激活UCP2是预防和治疗缺血性中风的一种有吸引力的策略。
