电生理研究支持 SK 通道正调节剂在治疗脊髓小脑共济失调 2 型中的效用。
Electrophysiological Studies Support Utility of Positive Modulators of SK Channels for the Treatment of Spinocerebellar Ataxia Type 2.
机构信息
Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia.
Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
出版信息
Cerebellum. 2022 Oct;21(5):742-749. doi: 10.1007/s12311-021-01349-1. Epub 2022 Jan 3.
Spinocerebellar ataxia type 2 (SCA2) is an incurable hereditary disorder accompanied by cerebellar degeneration following ataxic symptoms. The causative gene for SCA2 is ATXN2. The ataxin-2 protein is involved in RNA metabolism; the polyQ expansion may interrupt ataxin-2 interaction with its molecular targets, thus representing a loss-of-function mutation. However, mutant ataxin-2 protein also displays the features of gain-of-function mutation since it forms the aggregates in SCA2 cells and also enhances the IP3-induced calcium release in affected neurons. The cerebellar Purkinje cells (PCs) are primarily affected in SCA2. Their tonic pacemaker activity is crucial for the proper cerebellar functioning. Disturbances in PC pacemaking are observed in many ataxic disorders. The abnormal intrinsic pacemaking was reported in mouse models of episodic ataxia type 2 (EA2), SCA1, SCA2, SCA3, SCA6, Huntington's disease (HD), and in some other murine models of the disorders associated with the cerebellar degeneration. In our studies using SCA2-58Q transgenic mice via cerebellar slice recording and in vivo recording from urethane-anesthetized mice and awake head-fixed mice, we have demonstrated the impaired firing frequency and irregularity of PCs in these mice. PC pacemaker activity is regulated by SK channels. The pharmacological activation of SK channels has demonstrated some promising results in the electrophysiological experiments on EA2, SCA1, SCA2, SCA3, SCA6, HD mice, and also on mutant CACNA1A mice. In our studies, we have reported that the SK activators CyPPA and NS309 converted bursting activity into tonic, while oral treatment with CyPPA and NS13001 significantly improved motor performance and PC morphology in SCA2 mice. The i.p. injections of chlorzoxazone (CHZ) during in vivo recording sessions converted bursting cells into tonic in anesthetized SCA2 mice. And, finally, long-term injections of CHZ recovered the precision of PC pacemaking activity in awake SCA2 mice and alleviated their motor decline. Thus, the SK activation can be used as a potential way to treat SCA2 and other diseases accompanied by cerebellar degeneration.
脊髓小脑性共济失调 2 型(SCA2)是一种无法治愈的遗传性疾病,伴有小脑退行性变和共济失调症状。SCA2 的致病基因为 ATXN2。ataxin-2 蛋白参与 RNA 代谢;多聚 Q 扩展可能中断 ataxin-2 与其分子靶标的相互作用,因此代表功能丧失突变。然而,突变型 ataxin-2 蛋白也表现出功能获得性突变的特征,因为它在 SCA2 细胞中形成聚集体,并且还增强受影响神经元中 IP3 诱导的钙释放。SCA2 中主要受影响的是小脑浦肯野细胞(PCs)。它们的紧张性起搏活动对于小脑的正常功能至关重要。在许多共济失调疾病中观察到 PC 起搏的紊乱。在发作性共济失调 2 型(EA2)、SCA1、SCA2、SCA3、SCA6、亨廷顿病(HD)的小鼠模型以及与小脑退行性变相关的一些其他小鼠模型中,已经报道了异常的内在起搏。在我们使用 SCA2-58Q 转基因小鼠通过小脑切片记录和在戊巴比妥钠麻醉小鼠和清醒固定头部小鼠中的体内记录的研究中,我们已经证明了这些小鼠中 PC 的放电频率和不规则性受损。PC 起搏活动由 SK 通道调节。SK 通道的药理学激活在 EA2、SCA1、SCA2、SCA3、SCA6、HD 小鼠以及突变 CACNA1A 小鼠的电生理实验中显示出一些有希望的结果。在我们的研究中,我们报告说,SK 激活剂 CyPPA 和 NS309 将爆发活动转化为紧张性,而 CyPPA 和 NS13001 的口服治疗显著改善了 SCA2 小鼠的运动表现和 PC 形态。在体内记录过程中,腹腔内注射氯唑沙宗(CHZ)可将麻醉 SCA2 小鼠中的爆发细胞转化为紧张性。最后,长期注射 CHZ 恢复了清醒 SCA2 小鼠 PC 起搏活动的精度,并减轻了它们的运动下降。因此,SK 激活可用作治疗 SCA2 和其他伴有小脑退行性变的疾病的潜在方法。