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

总结： 神经元缠结（NFT）的形成是由微管相关蛋白聚集形成的。 tau蛋白（MAPT）是阿尔茨海默病（AD）的标志，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靶向NFT的形成， AD的分子原因基于我们的学术研究，我们将开发一种基于siRNA的产品， 经鼻给药，预防AD早期NFT的形成。 在之前的研究中，我们从MAPT基因中鉴定出了人类特异性环状RNA， 通过将外显子12反向剪接到外显子7或外显子10。这些tau circRNA在表观遗传后被翻译， 将腺苷残基改变为肌苷的修饰（A>I编辑）。翻译的蛋白质对应于 微管结合域的多聚体，并促进NFT的形成。 我们的公司CircCure将开发选择性靶向tau circRNA的siRNA，从而防止NFT 我们将在两个特定目标中测试该产品：目标#1：定义最佳siRNA骨架序列 对于12->7和12->10 tau circRNA，通过进行寡步移以鉴定具有 对tau circRNA的效力最高，对线性RNA的效力最低。经过标准 在目标#2中，我们将使用鼻内和注射递送测试siRNA功效（IC 50）， 一种移植到小鼠大脑中的人类神经母细胞瘤细胞的体内模型。该产品具有很强的创新性， 将直接解决NFT形成靶向最近发现的环状RNA。 这些I期研究的最终产物将是可以鼻内递送的siRNA， 减少包埋在小鼠脑中的人细胞中的tau circRNA和NFT形成。因此，该产品将 直接针对AD中神经元死亡的原因，这将为II期研究提供支持性证据， 在那里，我们将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.