Exosome-mediated propagation of disease linked poly-dipeptides in C9orf72-FTD/ALS

越来越多的证据揭示了额颞叶痴呆（FTD）的倾向， 肌萎缩侧索硬化症（ALS）致病蛋白从细胞到细胞传播。虽然其他一些 虽然已经提出了许多机制，但据报道外泌体的分泌发生在不同的神经细胞中， 细胞类型，包括神经元，并可能作为一种新的细胞间通讯途径， CNS。有趣的是，根据临床上的病灶性和神经解剖学传播的证据， 症状，也假设脑脊液（CSF）可以作为媒介物， 致病蛋白扩散，至少在ALS中是这样。 利用不同的体外细胞培养平台，包括来源于iPSC的脊髓运动神经元 在C9 orf 72患者中，我们最近了解到C9 orf 72连接的二肽蛋白（DPR）在 通过外泌体依赖的途径对神经细胞进行调控。通过分析一个新产生的外来体报告基因， 在转基因小鼠中，我们还发现外泌体能够在体内迁移广泛的距离。 这些观察结果使我们假设，外泌体介导的DPR繁殖可能是一个重要的机制。 C9 orf 72-FTD/ALS中毒性损伤在患病CNS区域扩散的方式。我们将 使用互补的体外和体内方法进行测试， 通过外泌体将损伤转移到相邻细胞，也转移到突触回路下游的神经元。 我们的主要工作是：（1）研究外泌体介导的DPRs在中枢神经系统细胞中的传递机制; (2)研究DPRs在体内的细胞间增殖方式;（3）研究DPRs是否 DPR的细胞转移传播毒性。 该工作有望为C9 orf 72 FTD/ALS的研究开辟一个全新的领域 研究，同时，为大脑中的基本生物过程提供重要线索 与脑部疾病有关的细胞通讯因此，预计结果将具有显著的 对理解C9 orf 72相关FTD/ALS发病机制和最终治疗患者的影响。

A growing body of evidence uncovered a propensity for frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) pathogenic proteins to propagate from cell-to-cell. Although few other mechanisms have been proposed, secretion of exosomes has been reported to occur from different neural cell types, including neurons, and to potentially serve as a new intercellular communication route within the CNS. Interestingly, based on the evidence of focality and neuroanatomical propagation of clinical symptoms, it was also hypothesized that the cerebro-spinal fluid (CSF) could serve as vehicle for pathogenic proteins spread, at least in ALS. Utilizing different in vitro cell culture platforms, including spinal motor neurons derived from iPSCs of C9orf72 patients, we recently learnt that C9orf72-linked dipeptide proteins (DPRs) spread between neural cells via the exosome-dependent pathway. By analyzing a newly generated exosome-reporter transgenic mouse, we also found that exosomes are capable of migrating extensive distance in vivo. These observations led us to postulate that an exosome-mediated propagation of DPRs could be a modality by which toxic insults spread in disease-afflicted CNS areas in C9orf72-FTD/ALS. We will be testing using complementary in vitro and in vivo approaches the novel hypothesis that transmitted DPRs transfer injury via exosomes to both neighboring cells, but also to neurons downstream in synaptic circuits. We propose: (1) To investigate exosome-mediated mechanisms of DPRs transmission in CNS cells; (2) To examine the modalities of cell-to-cell propagation of DPRs in vivo; (3) To examine whether cell transfer of DPRs propagates toxicity. The proposed work has the potential to open up an entirely new field of C9orf72 FTD/ALS research, at the same time, providing important clues to the fundamental biological processes in brain cellular communications relevant to brain diseases. Thus, the results are expected to have a significant impact for understanding C9orf72-linked FTD/ALS pathogenesis and eventually treating patients.