Role of Tau in Microtubule Stability in Adult Neurons

项目总结/摘要 Tau是一种集中在轴突中的纤维状微管相关蛋白，它与微管结合， 影响其性能。几十年来，流行的理论一直是tau蛋白稳定了微管， 轴突这是基于试管研究表明，过量的tau蛋白确实可以稳定微管，以及 过表达研究表明，在非神经元细胞中也是如此。疾病研究人员如此 投资于tau蛋白作为微管稳定剂的想法，目前正在使用微管稳定药物 用于治疗阿尔茨海默氏症等疾病，其中tau蛋白失去了与微管的联系。近期刊发 首席研究员的工作挑战了这一教条，建立在tau蛋白在大脑中富集的证据基础上。 轴突中微管的不稳定域比稳定域。此外，在这项工作中，当陶是 用RNA干扰从神经元中耗尽，微管质量损失，但不是由于 微管稳定区域的不稳定。相反，有一个不稳定的优先损失， 结构域，其余部分的不稳定结构域实际上变得更稳定，而不是不稳定。 进一步的研究表明，tau蛋白通过与真正的tau蛋白竞争， 微管稳定剂，如MAP 6，也促进组装的不稳定结构域。这是一个惊人的 与科学文献中已经确立的情况不同， 转变为tau的基础科学和医学科学。然而，所有这些工作都是在 在培养中发育啮齿动物神经元，非常真实的可能性是，成年人大脑中的情况不一样。 在这项提案中，主要研究者试图测试这些发现是否适用于成年小鼠大脑，使用 病毒驱动的RNA干扰以降低tau水平。从那里，研究建议深入研究拟议的 tau蛋白和真正的微管稳定剂如MAP 6之间的竞争， 在非神经元细胞中，这些蛋白质与微管的结合 可以很容易地可视化。总的来说，这些研究将大大有助于了解tau蛋白，这是一个至关重要的 蛋白质的轴突的正常功能和疾病，并将打开大门，以机制为基础的 治疗以纠正疾病中tau功能丧失的不良影响。

PROJECT SUMMARY / ABSTRACT Tau, a fibrous microtubule-associated protein concentrated in the axon, binds to microtubules, thereby influencing its properties. For decades, the prevailing theory has been that tau stabilizes microtubules in the axon. This is based on test tube studies showing that excess tau can indeed stabilize microtubules, as well as overexpression studies showing this to be the case in non-neuronal cells as well. Disease researchers are so invested in the idea of tau as a microtubule stabilizer that work is underway to use microtubule-stabilizing drugs to treat diseases such as Alzheimer’s, in which tau loses its association with microtubules. Recent published work of the Principal Investigator has challenged this dogma, building on evidence that tau is enriched on the labile domains of microtubules in the axon than on the stable domains. Moreover, in that work, when tau was depleted from the neuron with RNA interference, there was a loss of microtubule mass but not due to destabilization of the stable domains of the microtubules. Rather, there was a preferential loss of the labile domains, with the remaining portion of the labile domains actually becoming more stable rather than less stable. Additional studies suggested that tau prevents the labile domain from becoming stable by outcompeting genuine microtubule-stabilizers such as MAP6, and also promotes the assembly of the labile domain. This is a strikingly different scenario from the one that has become so established in the scientific literature, and potentially transformational to both the basic sciences and medical sciences of tau. However, all of that work was done on developing rodent neurons in culture, with the very real possibility that the situation is not the same in adult brain. In this proposal, the Principal Investigator seeks to test whether the findings hold true in adult mouse brain, using viral-driven RNA interference to lower tau levels. From there, studies are proposed to delve into the proposed competition between tau and genuine microtubule stabilizers such as MAP6 by ectopically expressing fluorescently tagged versions of them in non-neuronal cells in which binding of these proteins to microtubules can be readily visualized. Collectively, these studies will contribute significantly to understanding of tau, a crucial protein for both normal functioning of the axon and for disease, and will open the door toward mechanism-based therapies to rectify the ill effects of tau loss-of-function in disease.