The Sigma1 protein as a target for therapeutic management of epilepsy: preclinical validation in chronic mouse models

在兽医和人类医学中，长期服用抗癫痫药物是治疗癫痫的主要方法之一。不幸的是，相关数量的患者并未获得满意的治疗成功和癫痫控制。此外，大多数现有药物已被开发用于抑制癫痫发作，但并未针对病理生理机制和发挥疾病修正作用而设计。改变疾病的方法的发展有望产生更有效的战略，帮助降低疾病的内在严重性并克服耐药性。Sigma1是一种非典型受体蛋白，位于内质网膜上，具有伴侣功能。作为对细胞应激的响应，Sigma1影响内质网-线粒体界面的钙信号，并在转运到细胞膜上时，与不同的离子通道和受体相互作用。虽然Sigma1似乎在正常和基础细胞功能中并不起主要作用，但当体内平衡受到疾病状态下的病理生理机制的威胁时，它似乎具有重要的保护和调节功能。因此，Sigma1被认为是一个很有潜力的靶点，具有介导疾病改善作用的潜力。在我们的项目中，我们将研究Sigma1在两种不同的小鼠癫痫模型组织中的表达的保存和疾病相关的调节。然后，我们将讨论Sigma1的遗传和药理学靶向影响癫痫阈值、癫痫参数和超兴奋网络发展的假说。此外，还将评估对行为改变的影响。将在两种慢性小鼠癫痫模型中分别研究各自的影响，杏仁核点燃模式与反复癫痫诱导的杏仁核点燃模式，以及海马内海人酸模型与自发反复癫痫发作的发展。Sigma1基因缺陷的后果将通过Sigma1基因敲除小鼠和野生型小鼠之间的比较来探索。在药理学靶向方面，将测试以下Sigma1配体：E1R作为选择性正变构调节剂；NE-100作为选择性拮抗剂；芬氟拉明与5-羟色胺能信号转导和Sigma1的联合作用机制。此外，我们将测试与NE-100的药物组合，以确认化合物与Sigma1相互作用对E1R的相关性，并确定化合物与Sigma1相互作用对芬氟拉明的相对贡献。预计这些实验结果将为未来帮助克服耐药性的新型疾病修改方法的翻译开发提供基础。

Chronic administration of antiseizure drugs represents one of the mainstays for therapeutic management of epilepsy in veterinary and human medicine. Unfortunately, a satisfactory therapeutic success and seizure control is not achieved in a relevant number of patients. Moreover, the majority of available drugs have been developed to suppress seizures, but have not been designed to target pathophysiological mechanisms and to exert disease-modifying effects. The development of disease-modifying approaches holds the promise to result in more efficacious strategies helping to reduce the intrinsic severity of the disease and to overcome drug resistance. Sigma1 is an atypical receptor protein that is located in the endoplasmic reticulum membrane and serves a chaperone function. In response to cell stress Sigma1 affects calcium signaling at the ER-mitochondrial interface and, upon translocation to the cell membrane, interacts with different ion channels and receptors. While Sigma1 does not seem to play a major role in normal and basal cell function, it seems to serve an important protective and regulatory function, when homeostasis is threatened by pathophysiological mechanisms in disease states. Therefore, Sigma1 is considered as a promising target with the potential to mediate disease-modifying effects. In our project, we will study the preservation and disease-associated regulation of Sigma1 expression in tissue from two different mouse epilepsy models. We will then address the hypothesis that genetic and pharmacological targeting of Sigma1 affects seizure thresholds, seizure parameters, and development of a hyperexcitable network. In addition, the impact on behavioral alterations will be assessed. Respective effects will be studied in two chronic mouse epilepsy models, the amygdala kindling paradigm with repeated seizure induction and the intrahippocampal kainate model with development of spontaneous recurrent seizures. The consequences of Sigma1 genetic deficiency will be explored by comparison between Sigma1 knockout and wildtype mice. For pharmacological targeting the following Sigma1 ligands will be tested: E1R as a selective positive allosteric modulator; NE-100 as a selective antagonist; fenfluramine with combined mechanism of action with effects on serotonergic signaling and Sigma1. In addition, we will test drug combinations with NE-100 to confirm the relevance of the compound’s interaction with Sigma1 for E1R and to determine the relative contribution of the compound’s interaction with Sigma1 for fenfluramine. It is expected that the experimental findings provide a basis for future translational development of novel disease-modifying approaches that help to overcome drug resistance.