Duncan Jeremy W, Johnson Shakevia, Zhang Xiao, Zheng Baoying, Luo Jia, Ou Xiao-Ming, Stockmeier Craig A, Wang Jun Ming
Program in Neuroscience , University of Mississippi Medical Center, Jackson, Mississippi.
Department of Psychiatry and Human Behavior , University of Mississippi Medical Center, Jackson, Mississippi.
Alcohol Clin Exp Res. 2016 Nov;40(11):2320-2328. doi: 10.1111/acer.13209. Epub 2016 Sep 20.
Ethanol (EtOH) neurotoxicity can result in devastating effects on brain and behavior by disrupting homeostatic signaling cascades and inducing cell death. One such mechanism involves double-stranded RNA activated protein kinase (PKR), a primary regulator of protein translation and cell viability in the presence of a virus or other external stimuli. EtOH-mediated up-regulation of interferon-gamma (IFN-γ; the oxidative stress-inducible regulator of PKR), PKR, and its target, p53, are still being fully elucidated.
Using Western blot analysis, immunofluorescence, and linear regression analyses, changes in the IFN-γ-PKR-p53 pathway following chronic EtOH treatment in the frontal cortex of rodents were examined. The role of PKR on cell viability was also assessed in EtOH-treated cells using PKR overexpression vector and PKR inhibitor (PKRI).
In rats chronically fed EtOH, PKR, phosphorylated PKR (p-PKR), IFN-γ, and p53 were significantly increased following chronic EtOH exposure. Linear regression revealed a significant correlation between IFN-γ and p-PKR protein levels, as well as p-PKR expression and age of EtOH exposure. Overexpression of PKR resulted in greater cell death, while use of PKRI enhanced cell viability in EtOH-treated cells.
Chronic EtOH exposure activates the IFN-γ-PKR-p53 pathway in the frontal cortex of rodents. p-PKR expression is greater in brains of rodents exposed to EtOH at earlier ages compared to later life, suggesting a mechanism by which young brains could be more susceptible to EtOH-related brain injury. PKR and p-PKR were also colocalized in neurons and astrocytes of rats. This study provides additional insight into biochemical mechanisms underlying alcohol use disorder related neuropathology and warrants further investigation of PKR as a potential pharmacotherapeutic target to combat EtOH-related neurotoxicity, loss of protein translation and brain injury.
乙醇（EtOH）神经毒性可通过破坏稳态信号级联反应和诱导细胞死亡，对大脑和行为产生毁灭性影响。其中一种机制涉及双链RNA激活蛋白激酶（PKR），它是在病毒或其他外部刺激存在时蛋白质翻译和细胞活力的主要调节因子。乙醇介导的干扰素-γ（IFN-γ；PKR的氧化应激诱导调节因子）、PKR及其靶点p53的上调机制仍在深入研究中。
采用蛋白质免疫印迹分析、免疫荧光和线性回归分析，检测慢性乙醇处理后啮齿动物额叶皮质中IFN-γ-PKR-p53信号通路的变化。还使用PKR过表达载体和PKR抑制剂（PKRI）评估了PKR在乙醇处理细胞中对细胞活力的作用。
在长期喂食乙醇的大鼠中，慢性乙醇暴露后PKR、磷酸化PKR（p-PKR）、IFN-γ和p53显著增加。线性回归显示IFN-γ与p-PKR蛋白水平之间以及p-PKR表达与乙醇暴露年龄之间存在显著相关性。PKR过表达导致更多细胞死亡而使用PKRI可提高乙醇处理细胞的活力。
慢性乙醇暴露可激活啮齿动物额叶皮质中的IFN-γ-PKR-p53信号通路。与成年后相比，幼年暴露于乙醇的啮齿动物大脑中p-PKR表达更高，这表明幼年大脑可能更容易受到乙醇相关脑损伤的一种机制。PKR和p-PKR也共定位于大鼠的神经元和星形胶质细胞中。本研究为酒精使用障碍相关神经病理学的生化机制提供了更多见解，并值得进一步研究PKR作为对抗乙醇相关神经毒性、蛋白质翻译丧失和脑损伤的潜在药物治疗靶点。
