Targeting the lysosome-mitochondria axis in neurodegenerative lysosomal storage diseases - Lessons from telomerase immortalization

我们已经确定了端粒酶永生化和NPC纠正之间的联系1 脂质储存表型此外，我们最近已经确定了应激转录 NRF 1因子作为端粒酶诱导的基因之一，特别是在已经 在应激下，例如以溶酶体损伤为特征的尼曼-皮克C病细胞， 胆固醇储存这些结果特别令人兴奋，因为在许多细胞中， NRF 1的功能，最近被证明是一个核心球员在细胞 胆固醇稳态 我们随后确定，NRF 1单独异位表达可以纠正 NPC 1胆固醇储存表型表明NRF 1提供了一个联系， 线粒体和溶酶体的功能，在应激（疾病）条件下，NRF 1可以 规范其功能。因此，我们已经确定了一种转录因子， 靶向NPC 1疾病和潜在地用于许多其它溶酶体胆积症。 然而，已知转录因子是众所周知的难以药物化的， 由于其严格且往往错综复杂的监管，因此存在独特的挑战。为这些 我们兴奋地发现了两种独特的方法来激活靶细胞中的NRF 1， 疾病细胞。首先，使用我们开发的一种新的转录激活试验， 已经发现了一组FDA批准的钙通道抑制剂， NRF 1的激活剂。其次，我们发现了端粒酶的一个有趣的特性， 永生化NPC 1细胞;它们分泌含有高水平活性NRF 1的外泌体 能够将这种转录因子转移到靶细胞。 通过靶向NRF 1，该提案的目标首先是验证其治疗作用。 潜在的治疗NPC 1疾病，从而解决了巨大的未满足的需求。二是 使用NPC 1疾病的动物模型评估它们的体内治疗效果。 这些研究的成功将为这种新方法提供临床前验证 并为进一步的治疗开发提供理论基础。

We have identified a link between telomerase immortalization and correction of the NPC1 lipid storage phenotype. Furthermore, we have recently identified the stress transcription factor NRF1 as one of the genes induced by telomerase, especially in cells that are already under stress such as Niemann-Pick C disease cells characterized by lysosomal cholesterol storage. These results are particularly exciting since among many cellular functions assigned to NRF1 it was recently shown to be a central player in cellular cholesterol homeostasis. We subsequently determined that ectopic expression of NRF1 alone could correct the NPC1 cholesterol storage phenotype suggesting that NRF1 provides a link between mitochondria and lysosome function and under stress (disease) conditions NRF1 could normalize their function. Thus, we have identified a transcription factor that is a novel target for NPC1 disease and potentially for many other lysosomal storage disorders. It is known however, that transcription factors are notoriously difficult to drug and present unique challenges due to their tight and often intricate regulation. For these reasons we were excited to identify two unique methods for activating NRF1 in target, disease cells. First, using a novel transcriptional activation assay we have developed we have identified a group of FDA-approved calcium channel inhibitors that are very potent activators of NRF1. Second, we have identified an interesting property of telomerase immortalized NPC1 cells; they secreted exosomes that contain high levels of active NRF1 that are capable of transferring this trasncription factor to target cells. By targeting NRF1, the goals of this proposal are first to validate its therapeutic potential to treat NPC1 disease and thus address a great-unmet need. Second, to evaluate their therapeutic effectiveness in vivo using an animal model of NPC1 disease. The success of these studies will provide preclinical validation of this novel approach and provide the rationale for further therapeutic development.