Role of tau circular RNAs in tauopathies

微管相关蛋白tau(由MAPT基因编码)是骨肉瘤病因学的重要组成部分。 阿尔茨海默病(AD)和其他tau病，其中tau聚集在神经纤维缠结中。 然而，MAPT基因表达的基本调控机制仍不完全清楚。目前还不清楚 是什么导致神经原纤维缠结的形成，但tauopathic条件显示tau的变化 信使核糖核酸亚型，通过替代的前信使核糖核酸加工产生。此外，突变 改变MAPT的选择性剪接导致额颞部痴呆，强调了 Tau蛋白的前mRNA加工。我们已经鉴定出人类特有的环状RNA(CircRNAs)，由 外显子10的反向剪接产生的MAPT位点编码tau的mRNA。反向剪接的形成 当前mRNA形成环时，CircRNAs就会发生，这是在灵长类特有的Alu元素的帮助下 人类。突破性的初步数据证明了tau环状RNA的确凿证据。 从人脑样本中提取。我们假设铝元素有助于形成人类特有的 MAPT CircRNAs，可能在RNA甲基化后被翻译成含有 微管结合位点的多聚体。我们将在组织培养中使用(A)微型基因来进行分子 机制研究，以测试MAPT CircRNAs在RNA甲基化后是否翻译成蛋白质 并测试tau CircRNA与其他RNA和蛋白质的相互作用。这些数据将与 从病理证实的正常人类脑组织中进行的评估， 轻度认知障碍(MCI)和AD病例。为了(B)测试tau CircRNA的生理相关性，我们 已经产生了表达人类MAPT基因组部分的斑马鱼品系，这些基因组部分在 神经元，并在引入FTDP-17突变体后观察到异常神经元 只表达CircRNA。我们将确定转基因CircRNA的表达，它们编码的 蛋白质，其他RNA和蛋白质的可能隔离，神经元形态的变化，tau 并将这些数据与考虑压力的空间记忆测试相关联。这些是 首次报道和研究了人类tau环状RNA。这些研究意义重大，因为它们可以 提供一种新的、人类特有的分子机制来改变MAPT基因的表达，并可能提供一种 促进tau聚集体形成的新机制。我们的研究充分利用了优秀的 肯塔基大学的脑库，由Co-I博士Nelson博士领导，以及Co-I博士的斑马鱼专业知识 我是布莱克本医生。

Microtubule associated protein tau (encoded by the MAPT gene) is a critical component in the etiology of Alzheimer's Disease (AD) and other tauopathies in which tau aggregates in neurofibrillary tangles. However, the basic regulation of MAPT gene expression is still imperfectly understood. It is not clear what causes the formation of neurofibrillary tangles, but tauopathic conditions show changes in tau mRNA isoforms, generated through alternative pre-mRNA processing. Furthermore, mutations changing alternative splicing of MAPT cause frontotemporal dementia, underscoring the importance of tau pre-mRNA processing. We have identified human-specific circular RNAs (circRNAs) formed by the tau-encoding mRNA from the MAPT locus generated by backsplicing of exon 10. Backsplicing forming circRNAs occurs when pre-mRNA forms loops, which is aided by primate-specific Alu elements in humans. The ground-breaking preliminary data demonstrate conclusive evidence of tau circRNAs derived from human brain samples. We hypothesize that Alu elements help forming human specific MAPT circRNAs, that likely after RNA methylation could be translated into proteins containing multimers of microtubule binding sites. We will use (a) minigenes in tissue culture for molecular mechanistic studies, to test whether MAPT circRNAs are translated into proteins after RNA methylation and to test tau circRNA's interaction with other RNAs and proteins. These data will be correlated with assessments in human brain tissue across the disease spectrum from pathologically-confirmed normal, MCI (mild cognitive impairment), and AD cases. To (b) test tau circRNA's physiological relevance, we have generated zebrafish lines expressing genomic parts of human MAPT that form circular RNAs in neurons, and observed abnormal neurons after introduction of FTDP-17 mutants in constructs that express only circRNAs. We will determine the expression of transgenic circRNAs, their encoded proteins, possible sequestration of other RNAs and proteins, changes in neuron morphology, tau pathology and correlate these data with spatial memory tests that take stress into account. These are the first reports and studies of human tau circular RNAs. These studies are significant, as they could provide a novel, human-specific molecular mechanism to alter MAPT gene expression, and possibly a new mechanism to promote the formation of tau aggregates. Our studies capitalize on the excellent brain bank at the University of Kentucky, headed by Co-I Dr. Nelson, and the zebrafish expertise of Co- I Dr. Blackburn.