Using siRNAs against tau circular RNAs as a rational therapy for Alzheimer's disease

摘要： 微管聚集形成的神经原纤维缠结(NFT) 蛋白tau(MAPT)是阿尔茨海默病(AD)的一个标志，也是神经元死亡的可能原因。目前， 没有合理的治疗方法可以直接针对NFT的形成，从而解决直接的 阿尔茨海默病的分子病因。在我们学术研究的基础上，我们将开发一种基于siRNA的产品，它可以 鼻腔给药，防止AD早期形成NFT。 在先前的研究中，我们从MAPT基因中识别出人类特有的环状RNA 通过外显子12到外显子7或外显子10的反向剪接。这些tau环状RNA在表观遗传后被翻译 将腺苷残基改变为肌苷的修饰(A&gt；I编辑)。翻译的蛋白质对应于 微管结合域的多聚体和促进NFT的形成。 我们的CircCure公司将开发选择性靶向tau CircRNA的siRNA，从而防止NFT 形成；我们将在两个特定目标中测试该产品：目标1：确定最佳的siRNA骨架序列 对于12-gt；7和12-gt；10 tau CircRNA，通过执行寡走来识别具有 对tau环状RNA的药效最高，对线性RNA的药效最低。在经历了标准 化学优化，在目标2中，我们将测试siRNA的有效性(IC50)，使用鼻腔和注射给药 人神经母细胞瘤细胞移植于小鼠脑内的体内模型。这种产品具有很强的创新性，因为它 将直接解决针对最近发现的环状RNA的NFT形成。 这些第一阶段研究的最终产品将是一种siRNA，它可以通过鼻腔输送 减少嵌入在小鼠大脑中的人类细胞中tau环状RNA和NFT的形成。因此，该产品将 直接针对AD神经元死亡的原因，这将为第二阶段研究提供支持性证据， 我们将在那里测试药理学和安全性，为研究性新药(IND)申请做准备。

Summary: The formation of neurofibrillary tangles (NFT) formed by aggregation of the microtubule-associated protein tau (MAPT) is a hallmark of Alzheimer’s disease (AD) and the likely cause of neuronal death. Currently, there are no rational treatments available that directly target NFT formation and thus address the direct molecular cause for AD. Based on our academic research, we will develop an siRNA-based product that can be delivered nasally and prevents NFT formation in early stages of AD. In prior studies, we identified human-specific circular RNAs from the MAPT gene that are generated through backsplicing of exon 12 to either exon 7 or exon 10. These tau circRNAs are translated after epigenetic modifications that change adenosine residues to inosines (A>I editing). The translated proteins correspond to multimers of the microtubule-binding domain and promote NFT formation. Our company, CircCure, will develop siRNAs that selectively target tau circRNAs and thus prevent NFT formation; we will test this product in two specific aims: Aim #1: Define the optimal siRNA backbone sequence for the 12->7 and 12->10 tau circRNA by performing an oligo-walk to identify the backbone sequence with the highest efficacy toward tau circRNAs and lowest efficacy against linear RNAs. After undergoing standard chemical optimization, in Aim #2, we will test the siRNA efficacy (IC50) using intranasal and injection delivery in an in vivo model of human neuroblastoma cells grafted in mouse brains. This product is highly innovative, as it will directly address NFT formation targeting recently discovered circular RNAs. The final product of these Phase I studies will be an siRNA that can be delivered intranasally that reduces tau circRNAs and NFT formation in human cells embedded in a mouse brain. The product will thus directly target the cause of neuronal death in AD, which will provide supportive evidence for Phase II studies, where we will test pharmacology and safety to prepare for an investigational new drug (IND) application.