Laboratory of Immunobiology, School of Life Science, College of Natural Sciences, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea; AT-31 BIO Inc., Business Incubation Center, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea.
Laboratory of Immunobiology, School of Life Science, College of Natural Sciences, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu 41566, Republic of Korea.
Biomed Pharmacother. 2024 Nov;180:117538. doi: 10.1016/j.biopha.2024.117538. Epub 2024 Oct 10.
Oxidative stress and mitochondrial dysfunction play critical roles in neurodegenerative diseases. Glutathione (GSH), a key brain antioxidant, helps to neutralize reactive oxygen species (ROS) and maintain redox balance. We investigated the effectiveness of L-cysteine (L-Cys) in preventing apoptosis induced by the ROS generator 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) in mouse hippocampal neuronal HT22 cells, as well as alleviating memory and cognitive impairments caused by the GSH synthesis inhibitor L-buthionine sulfoximine (BSO) in mice. DMNQ-induced apoptotic events in HT22 cells, including elevated cytosolic and mitochondrial ROS levels, DNA fragmentation, endoplasmic reticulum stress, and mitochondrial damage-mediated apoptotic pathways were dose-dependently abrogated by L-Cys (0.5-2 mM). The reduced intracellular GSH level, caused by DMNQ treatment, was restored by L-Cys cotreatment. Although L-Cys did not significantly restore GSH in the presence of BSO, it prevented DMNQ-induced ROS elevation, mitochondrial damage, and apoptosis. Furthermore, compared to N-acetylcysteine and GSH, L-Cys had higher 2,2-diphenyl-1-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid radical-scavenging activity. L-Cys also restored mitochondrial respiration capacity in DMNQ-treated HT22 cells by reversing mitochondrial fission-fusion dynamic balance. BSO administration (500 mg/kg/day) in mice led to neuronal deficits, including memory and cognitive impairments, which were effectively mitigated by oral L-Cys (15 or 30 mg/kg/day). L-Cys also reduced BSO-induced ROS levels in the mice hippocampus and cortex. These findings suggest that even though it does not contribute to intracellular GSH synthesis, exogenous L-Cys protects neuronal cells against oxidative stress-induced mitochondrial damage and apoptosis, by acting as a ROS scavenger, which is beneficial in ameliorating neurocognitive deficits caused by oxidative stress.
氧化应激和线粒体功能障碍在神经退行性疾病中起着关键作用。谷胱甘肽 (GSH) 是一种关键的脑抗氧化剂，有助于中和活性氧 (ROS) 并维持氧化还原平衡。我们研究了 L-半胱氨酸 (L-Cys) 预防 ROS 生成剂 2,3-二甲氧基-1,4-萘醌 (DMNQ) 在小鼠海马神经元 HT22 细胞中诱导的细胞凋亡的效果，以及减轻 GSH 合成抑制剂 L-丁硫氨酸亚砜 (BSO) 在小鼠中引起的记忆和认知障碍。DMNQ 诱导 HT22 细胞发生凋亡事件，包括细胞浆和线粒体 ROS 水平升高、DNA 片段化、内质网应激和线粒体损伤介导的凋亡途径，这些均被 L-Cys（0.5-2 mM）呈剂量依赖性抑制。L-Cys 还可逆转 DMNQ 引起的线粒体分裂融合动态平衡，从而恢复 HT22 细胞中 DMNQ 引起的呼吸能力下降。DMNQ 处理引起的细胞内 GSH 水平降低可通过 L-Cys 共处理得到恢复。尽管 L-Cys 不能显著恢复 BSO 存在时的 GSH，但它可防止 DMNQ 引起的 ROS 升高、线粒体损伤和凋亡。与 N-乙酰半胱氨酸和 GSH 相比，L-Cys 具有更高的 2,2-二苯基-1-苦基肼基和 2,2-联氮-双-3-乙基苯并噻唑啉-6-磺酸自由基清除活性。BSO（500 mg/kg/天）给药可导致小鼠神经元缺失，包括记忆和认知障碍，而口服 L-Cys（15 或 30 mg/kg/天）可有效缓解这些障碍。L-Cys 还可降低 BSO 诱导的小鼠海马和皮质中的 ROS 水平。这些发现表明，尽管 L-Cys 本身不能促进细胞内 GSH 的合成，但它可作为 ROS 清除剂，通过防止氧化应激诱导的线粒体损伤和凋亡来保护神经元细胞，这有利于改善氧化应激引起的神经认知缺陷。
