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Elucidation of pathomechanism and development of treatment of spinocerebellar ataxia type 6

脊髓小脑性共济失调6型发病机制的阐明及治疗进展

基本信息

批准号：
17209031
负责人：
MIZUSAWA Hidehiro
金额：
$ 32.03万
依托单位：
Tokyo Medical and Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17209031/
关键词：
polyglutamine disease SCA6 P Q type calcium channel gene therapy neurodegeneration splicing 脊髄小脳変性症6型 SCA6 Caチャンネル RNAi 動物モデル培養細胞

项目摘要

1. In order to model SCA6 in mice, we generated three strains of knock-in (KI) mice carrying normal, expanded, or hyper-expanded CAG repeat tracts in Cacna1a locus. Based on the analysis of these animals, we found that the expanded CAG repeat per se does not affect the intrinsic electrophysiological properties of the channel and the pathogenesis of SCA6 was apparently linked to an age-dependent process accompanied with accumulation of mutant Cav2.1 channel protein.2. Using cellular models, KI cerebella, and postmortem patients' samples, we revealed that expansion of the CAG repeat tract affected splice-site selection at CACNA1A exon 47 locus, leading to the increased relative abundance of polyglutamine-containing Cav2.1 channels in cerebellar Purkinje neurons. Thus, the SCA6 mutation not only gives rise to transcripts encoding glutamine-expanded channel proteins, but also upregulates their expression, possibly by regulating splicing events.3. We confirmed that the Cav2.1 channel underg … More oes cleavage at its C-terminal portion in SCA6 cerebella. The role of the cleaved fragment in SCA6 pathogenesis is now being examined.4. Using cellular models expressing C-terminal fragment of ataxin-3 containing expanded polyglutamine, we demonstrated that the inhibition of Bax by BIPs (Bax-inhibiting polypepdides), which were developed as a series of cytoprotective membrane -permeable pentapeprides, markedly protected cells from polyglutamine-induced toxicity. Thus, Bax may be a key mediator of polyglutamine-induced toxicity and BIPs may provide a new strategy for developing therapeutics for polyglutamine diseases.5. We developed a new RNA interference strategy for treating dominantly inherited neurodegenerative diseases. We found that SCA6 allele could be selectively suppressed with this method in cells.6. We treated SCA6 patients with a potassium channel blocker 4-diaminopyridine (4-AP), which has been shown to increase the excitability of cerebellar Purkinje cells. These patients showed significant improvement in several aspects of clinical symptoms, suggesting that 4-AP may be useful for treating the disease. Less

1.为了在小鼠中模拟SCA 6，我们产生了三种在Cacna 1a基因座中携带正常、扩增或过度扩增的CAG重复序列的敲入（KI）小鼠品系。基于对这些动物的分析，我们发现扩展的CAG重复序列本身并不影响通道的内在电生理特性，SCA 6的发病机制显然与伴随突变Cav2.1通道蛋白积累的年龄依赖性过程有关.使用细胞模型，KI小脑，和尸检患者的样本，我们发现，CAG重复序列的扩展影响剪接位点选择CACNA 1A外显子47位点，导致小脑浦肯野神经元中含有多聚谷氨酰胺的Cav2.1通道的相对丰度增加。因此，SCA 6突变不仅产生编码谷氨酰胺扩展通道蛋白的转录本，而且可能通过调节剪接事件上调其表达。我们证实Cav2.1通道在 ...更多信息在小脑SCA 6的C-末端部分有分裂。切割片段在SCA 6发病机制中的作用正在研究中。使用表达含有扩展的聚谷氨酰胺的共济失调蛋白-3的C-末端片段的细胞模型，我们证明了BIP（抑制Bax的多肽）（其被开发为一系列细胞保护膜可渗透的五肽）对Bax的抑制显著地保护细胞免受聚谷氨酰胺诱导的毒性。因此，Bax可能是多聚谷氨酰胺诱导的毒性的关键介质，BIPs可能为开发多聚谷氨酰胺疾病的治疗方法提供新的策略。我们开发了一种新的RNA干扰策略用于治疗显性遗传性神经退行性疾病。我们发现该方法可以在细胞中选择性抑制SCA 6等位基因.我们用钾通道阻断剂4-氨基吡啶（4-AP）治疗SCA 6患者，该药物已被证明可增加小脑浦肯野细胞的兴奋性。这些患者在临床症状的几个方面表现出明显的改善，表明4-AP可能对治疗该疾病有用。少