Putra Marson, Rao Nikhil S, Gardner Cara, Liu Guanghao, Trommater Jordan, Bunney Michael, Gage Meghan, Bassuk Alexander G, Hefti Marco, Lee Gloria, Thippeswamy Thimmasettappa
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50010, USA.
Department of Internal Medicine, Carver College of Medicine, Carver College of Medicine University of Iowa, Iowa City, IA 52242, USA.
Brain Commun. 2024 Sep 19;6(5):fcae327. doi: 10.1093/braincomms/fcae327. eCollection 2024.
Epilepsy and Alzheimer's disease share some common pathologies such as neurodegeneration, seizures and impaired cognition. However, the molecular mechanisms of these changes are still largely unknown. Fyn, a Src-family non-receptor tyrosine kinase (SFK), and its interaction with tau in mediating brain pathology in epilepsy and Alzheimer's disease can be a potential therapeutic target for disease modification. Although Fyn and tau pathology occurs in both Alzheimer's disease and epilepsy, the dynamics of Fyn-tau and PSD95-NR2B interactions affected by seizures and their impact on brain pathology in epilepsy have not been investigated. In this study, we demonstrate a significant increase of Fyn-tau interactions following seizure induction by kainate in both acute and chronic rodent models and in human epilepsy. In the early phase of epileptogenesis, we show increased Fyn/tau/NR2B/PSD95/neuronal nitric oxide synthase complexes after status epilepticus and a postsynaptic increase of phosphorylated tau (pY18 and AT8), Fyn (pSFK-Y416), NMDAR (pNR2B-Y1472) and neuronal nitric oxide synthase. Hippocampal proximity ligation assay and co-immunoprecipitation revealed a sustained increase of Fyn-tau and NR2B-PSD95 complexes/binding in rat chronic epilepsy at 3 months post-status epilepticus. Enhanced Fyn-tau complexes strongly correlated with the frequency of spontaneously recurring convulsive seizures and epileptiform spikes in the chronic epilepsy model. In human epileptic brains, we also identified increased Fyn-tau and NR2B-PSD95 complexes, tau phosphorylation (pY18 and AT8) and Fyn activation (pSFK-Y416), implying the translational and therapeutic potential of these molecular interactions. In knockout mice and in rats treated with a Fyn/SFK inhibitor saracatinib, we found a significant reduction of phosphorylated Fyn, tau (AT8 in saracatinib-treated), NR2B and neuronal nitric oxide synthase and their interactions (Fyn-tau and NR2B-PSD95 in saracatinib-treated group; NR2B-PSD95 in knockout group). The reduction of Fyn-tau and NR2B-PSD95 interactions in the saracatinib-treated group, in contrast to the vehicle-treated group, correlated with the modification in seizure progression in the rat chronic epilepsy model. These findings from animal models and human epilepsy provide evidence for the role of Fyn-tau and NR2B-PSD95 interactions in seizure-induced brain pathology and suggest that blocking such interactions could modify the progression of epilepsy.
癫痫和阿尔茨海默病存在一些共同的病理特征，如神经退行性变、癫痫发作和认知障碍。然而，这些变化的分子机制仍 largely 未知。Fyn 是一种 Src 家族非受体酪氨酸激酶（SFK），其在癫痫和阿尔茨海默病中介导脑病理过程中与 tau 的相互作用可能是疾病修饰的潜在治疗靶点。尽管 Fyn 和 tau 病理在阿尔茨海默病和癫痫中均有发生，但癫痫发作对 Fyn-tau 和 PSD95-NR2B 相互作用的影响及其对癫痫脑病理的作用尚未得到研究。在本研究中，我们证实在急性和慢性啮齿动物模型以及人类癫痫中，经海藻酸诱导癫痫发作后 Fyn-tau 相互作用显著增加。在癫痫发生的早期阶段，我们发现癫痫持续状态后 Fyn/tau/NR2B/PSD95/神经元型一氧化氮合酶复合物增加，以及突触后磷酸化 tau（pY18 和 AT8）、Fyn（pSFK-Y416）、NMDAR（pNR2B-Y1472）和神经元型一氧化氮合酶增加。海马邻近连接分析和免疫共沉淀显示，在癫痫持续状态后 3 个月的大鼠慢性癫痫中，Fyn-tau 和 NR2B-PSD95 复合物/结合持续增加。在慢性癫痫模型中，增强的 Fyn-tau 复合物与自发复发性惊厥发作和癫痫样棘波的频率密切相关。在人类癫痫脑中，我们还发现 Fyn-tau 和 NR2B-PSD95 复合物增加、tau 磷酸化（pY18 和 AT8）以及 Fyn 激活（pSFK-Y416），这意味着这些分子相互作用具有转化和治疗潜力。在 Fyn/SFK 抑制剂萨拉卡替尼处理的敲除小鼠和大鼠中，我们发现磷酸化 Fyn、tau（萨拉卡替尼处理组中的 AT8）、NR2B 和神经元型一氧化氮合酶及其相互作用（萨拉卡替尼处理组中的 Fyn-tau 和 NR2B-PSD95；敲除组中的 NR2B-PSD95）显著减少。与载体处理组相比，萨拉卡替尼处理组中 Fyn-tau 和 NR2B-PSD95 相互作用的减少与大鼠慢性癫痫模型中癫痫发作进展的改变相关。这些来自动物模型和人类癫痫的发现为 Fyn-tau 和 NR2B-PSD95 相互作用在癫痫诱导的脑病理中的作用提供了证据，并表明阻断这种相互作用可能改变癫痫的进展。
