Song Min-Young, Hwang Ji Yeon, Bae Eun Ji, Kim Saesbyeol, Kang Hye-Min, Kim Yong Jun, Park Chan, Park Kang-Sik
Department of Physiology, College of Medicine, Kyung Hee University, Seoul 02447, Korea.
Department of Anatomy & Neurobiology, College of Medicine, Kyung Hee University, Seoul 02447, Korea.
Int J Mol Sci. 2020 Dec 15;21(24):9538. doi: 10.3390/ijms21249538.
In brain ischemia, oxidative stress induces neuronal apoptosis, which is mediated by increased activity of the voltage-gated K channel K2.1 and results in an efflux of intracellular K. The molecular mechanisms underlying the regulation of K2.1 and its activity during brain ischemia are not yet fully understood. Here this study provides evidence that oxidant-induced apoptosis resulting from brain ischemia promotes rapid tyrosine phosphorylation of K2.1. When the tyrosine phosphorylation sites Y124, Y686, and Y810 on the K2.1 channel are mutated to non-phosphorylatable residues, PARP-1 cleavage levels decrease, indicating suppression of neuronal cell death. The tyrosine residue Y810 on K2.1 was a major phosphorylation site. In fact, cells mutated Y810 were more viable in our study than were wild-type cells, suggesting an important role for this site during ischemic neuronal injury. In an animal model, tyrosine phosphorylation of K2.1 increased after ischemic brain injury, with an observable sustained increase for at least 2 h after reperfusion. These results demonstrate that tyrosine phosphorylation of the K2.1 channel in the brain may play a critical role in regulating neuronal ischemia and is therefore a potential therapeutic target in patients with brain ischemia.
在脑缺血中，氧化应激诱导神经元凋亡，这由电压门控钾通道K2.1活性增加介导，并导致细胞内钾外流。脑缺血期间K2.1及其活性调节的分子机制尚未完全阐明。本研究提供了证据表明脑缺血引起的氧化应激诱导的凋亡促进了K2.1的快速酪氨酸磷酸化。当K2.1通道上的酪氨酸磷酸化位点Y124、Y686和Y810突变为不可磷酸化残基时，PARP-1切割水平降低，表明神经元细胞死亡受到抑制。K2.1上的酪氨酸残基Y810是主要的磷酸化位点。事实上，在我们的研究中，Y810突变的细胞比野生型细胞更具活力，表明该位点在缺血性神经元损伤中起重要作用。在动物模型中，缺血性脑损伤后K2.1的酪氨酸磷酸化增加，再灌注后至少2小时可观察到持续增加。这些结果表明，脑中K2.1通道的酪氨酸磷酸化可能在调节神经元缺血中起关键作用，因此是脑缺血患者的潜在治疗靶点。
