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

抗癫痫药物的长期给药代表了兽医和人类医学中癫痫治疗管理的主要支柱之一。不幸的是，在相关数量的患者中没有实现令人满意的治疗成功和癫痫控制。此外，大多数可用的药物已被开发用于抑制癫痫发作，但尚未被设计为靶向病理生理机制和发挥疾病改善作用。疾病修饰方法的发展有望产生更有效的策略，有助于降低疾病的内在严重程度并克服耐药性。Sigma 1是一种非典型受体蛋白，位于内质网膜中，具有分子伴侣功能。响应于细胞应激，Sigma 1影响ER-线粒体界面处的钙信号传导，并且在易位到细胞膜时，与不同的离子通道和受体相互作用。虽然Sigma 1似乎在正常和基底细胞功能中不起主要作用，但当疾病状态中的病理生理机制威胁到稳态时，它似乎起重要的保护和调节功能。因此，Sigma 1被认为是一个有希望的靶点，具有介导疾病修饰作用的潜力。 在我们的项目中，我们将研究Sigma 1在两种不同小鼠癫痫模型组织中表达的保存和疾病相关调节。然后，我们将解决的假设，遗传和药理学靶向的Sigma 1影响癫痫发作阈值，癫痫发作参数，和发展的一个过度兴奋的网络。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研究各自的作用，即反复癫痫发作诱导的杏仁核点燃范式和自发性复发性癫痫发作的海马内红藻氨酸模型。Sigma 1基因缺陷的后果将通过Sigma 1基因敲除小鼠和野生型小鼠之间的比较来探讨。对于药理学靶向，将测试以下Sigma 1配体：E1 R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，其作用机制与对肾上腺素能信号传导和Sigma 1的影响相结合。此外，我们将测试NE-100的药物组合，以确认化合物与Sigma 1相互作用对E1 R的相关性，并确定化合物与Sigma 1相互作用对芬氟拉明的相对贡献。预计实验结果为未来有助于克服耐药性的新型疾病修饰方法的翻译开发提供了基础。

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.