Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA.
Department of Neuroscience, Carleton University, Ottawa, ON, Canada.
Ann Neurol. 2018 Feb;83(2):311-327. doi: 10.1002/ana.25149. Epub 2018 Feb 15.
Temporal lobe epilepsy (TLE) is a chronic epilepsy syndrome defined by seizures and progressive neurological disabilities, including cognitive impairments, anxiety, and depression. Here, human TLE specimens were investigated focusing on the mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) and complex 2 (mTORC2) activities in the brain, given that both pathways may represent unique targets for treatment.
Surgically resected hippocampal and temporal lobe samples from therapy-resistant TLE patients were analyzed by western blotting to quantify the expression of established mTORC1 and mTORC2 activity markers and upstream or downstream signaling pathways involving the two complexes. Histological and immunohistochemical techniques were used to assess hippocampal and neocortical structural abnormalities and cell-specific expression of individual biomarkers. Samples from patients with focal cortical dysplasia (FCD) type II served as positive controls.
We found significantly increased expression of phospho-mTOR (Ser2448), phospho-S6 (Ser235/236), phospho-S6 (Ser240/244), and phospho-Akt (Ser473) in TLE samples compared to controls, consistent with activation of both mTORC1 and mTORC2. Our work identified the phosphoinositide 3-kinase and Ras/extracellular signal-regulated kinase signaling pathways as potential mTORC1 and mTORC2 upstream activators. In addition, we found that overactive mTORC2 signaling was accompanied by induction of two protein kinase B-dependent prosurvival pathways, as evidenced by increased inhibitory phosphorylation of forkhead box class O3a (Ser253) and glycogen synthase kinase 3 beta (Ser9).
Our data demonstrate that mTOR signaling is significantly dysregulated in human TLE, offering new targets for pharmacological interventions. Specifically, clinically available drugs that suppress mTORC1 without compromising mTOR2 signaling, such as rapamycin and its analogs, may represent a new group of antiepileptogenic agents in TLE patients. Ann Neurol 2018;83:311-327.
颞叶癫痫（TLE）是一种以癫痫发作和进行性神经功能障碍为特征的慢性癫痫综合征，包括认知障碍、焦虑和抑郁。在这里，我们研究了人类 TLE 标本，重点关注了脑内雷帕霉素靶蛋白（mTOR）复合物 1（mTORC1）和复合物 2（mTORC2）的活性，因为这两条通路都可能代表治疗的独特靶点。
通过 Western blot 分析来自耐药性 TLE 患者的手术切除海马和颞叶样本，以定量测定已建立的 mTORC1 和 mTORC2 活性标志物以及涉及两个复合物的上游或下游信号通路的表达。使用组织学和免疫组织化学技术评估海马和新皮层的结构异常以及单个生物标志物的细胞特异性表达。FCD II 型局灶性皮质发育不良（FCD）患者的样本作为阳性对照。
与对照组相比，我们发现 TLE 样本中磷酸化 mTOR（Ser2448）、磷酸化 S6（Ser235/236）、磷酸化 S6（Ser240/244）和磷酸化 Akt（Ser473）的表达显著增加，这与 mTORC1 和 mTORC2 的激活一致。我们的工作确定了磷脂酰肌醇 3-激酶和 Ras/细胞外信号调节激酶信号通路是 mTORC1 和 mTORC2 的潜在上游激活剂。此外，我们发现过度活跃的 mTORC2 信号伴随着蛋白激酶 B 依赖性两个生存途径的诱导，这表现为叉头框 O3a（Ser253）和糖原合酶激酶 3β（Ser9）的抑制性磷酸化增加。
我们的数据表明，mTOR 信号在人类 TLE 中显著失调，为药物干预提供了新的靶点。具体来说，临床上可用的抑制 mTORC1 而不损害 mTOR2 信号的药物，如雷帕霉素及其类似物，可能代表 TLE 患者的一组新的抗癫痫药物。
