Dissecting the in vivo role of Huntingtin in Rab vesicle movement on microtubules

亨廷顿病（Huntington 'sDisease，HD）是一种严重的遗传性神经退行性疾病 其特征在于由于纹状体神经元的损失而引起的舞蹈病和认知障碍。目前没有 HD的有效治疗/治愈方法。目前使用的大多数治疗方法都是针对 溶解/解离聚集体并防止细胞死亡，这是终末期常见的神经病理学 疾病。虽然HD蛋白亨廷顿蛋白（HTT）对生存力至关重要，但HTT介导的细胞凋亡的复杂性并不重要。 关联指示多个功能。因此，挑战在于解开HTT的主要功能， 一旦被破坏就会引发疾病先前的工作提出了一个诱人的建议，即轴突的破坏 长而窄的轴突内的运输是引起蛋白质积累的早期事件， 死亡，最终导致HD中观察到的神经元功能障碍。我们的长期目标是了解 HTT介导的轴突运输缺陷启动疾病途径。我们的下一步目标是 在追求这一目标的过程中，是确定HTT如何影响特定小泡亚类的转运 (Rab蛋白质）。我们的中心假设是，由HTT介导的Rab囊泡在轴突内运输的中断， 可导致HD中观察到的早期神经病理学。这个假设有两个明确的预测; 1： HTT和Rab蛋白在相同的囊泡上，并且2：Rab囊泡使用驱动蛋白-1和动力蛋白马达来表达HTT和Rab蛋白。 微管运动（MT）。在这种情况下，我们的具体目标是确定HTT如何影响Rab蛋白 用于轴突内的MT依赖性运输。我们有5个具体目标，1：确定HTT如何影响拉布 2：测试HTT和Rab 11、Rab 32和RabX 4在相同囊泡上的预测，3：测试HTT和Rab 11、Rab 32和RabX 4在相同囊泡上的预测， Rab 32和RabX 4都在Rab 11囊泡上的预测，4：检验Rab 32和RabX 4都在Rab 11囊泡上的预测 使用驱动蛋白-1和动力蛋白马达在MT上运动，和5：测试突变HTT破坏的预测 Rab-mediated功能一个全面的体内方法将被用来解剖的生理作用， Rab囊泡在生物体中的运输。这项研究的基本原理是， HD疾病如何通过突变HTT扰动Rab转运而引发的机制是已知的，新的 并可以开发针对HD的创新方法。因此，确定HTT如何正常运作， 神经元将对提供新的靶向途径产生重大影响， 和治疗性干预，这是目前无法用于HD的。因此，我们的工作是创新的， 因为它代表了一种新的和实质性的脱离现状的做法，即 详细说明了HTT的作用，使用活生物体中囊泡运动的体内动力学。拟议 研究是重要的，因为它有望纵向推进和扩大我们对如何 疾病途径启动，这将大大改变目前的知识。获得的知识将 极大地推动了许多针对轴突缺陷的药理学或遗传修饰剂的发展 或恢复Rab功能（影响）。

Huntington's disease (HD) is a devastating, dominantly inherited neurodegenerative disease clinically characterized by chorea and cognitive impairment due to loss of striatal neurons. Currently there are no effective treatments/cures for HD. Most therapeutic treatments currently used are aimed at dissolving/dissociating aggregates and preventing cell death, common neuropathology seen at the end stage of disease. Although the HD protein, huntingtin (HTT) is critical for viability, the complexity of HTT-mediated associations indicates multiple functions. Thus the challenge is to unravel the primary function of HTT, which when disrupted initiates disease. Previous work put forth a tantalizing proposal that disruption of axonal transport within long, narrow-caliber axons is an early event that causes protein accumulations that elicit cell death, ultimately resulting in neuronal dysfunction observed in HD. Our long-term goal is to understand how HTT-mediated axonal transport defects initiates disease pathways. The objective here, which is our next step in the pursuit of this goal, is to determine how HTT influences the transport of a specific sub class of vesicles (Rab proteins). Our central hypothesis is that disruption of Rab vesicle transport within axons mediated by HTT can contribute to early neuropathology observed in HD. There are two clear predictions of this hypothesis; 1: HTT and Rab proteins are on the same vesicles and 2: Rab vesicles use kinesin-1 and dynein motors for movement on microtubules (MT). In this context our specific aim is to identify how HTT influences Rab proteins for MT-dependent transport within axons. We have 5 specific objectives, 1: determine how HTT influences Rab proteins, 2: test the prediction that HTT and Rab11, Rab32 and RabX4 are on the same vesicle, 3: test the prediction that Rab32 and RabX4 are both on the Rab11 vesicle, 4: test the prediction that Rab32 and RabX4 use kinesin-1 and dynein motors for movement on MT, and 5: test the prediction that mutant HTT disrupts Rab-mediated functions. A comprehensive in vivo approach will be used to dissect the physiological role of HTT in Rab vesicle transport in an organism. The rationale for the proposed research is that once the mechanisms of how HD disease is initiated by perturbations in Rab transport by mutant HTT are known, new and innovative approaches against HD can be developed. Therefore identifying how HTT normally functions in neurons will have a significant impact on providing novel target pathways for developing effective preventive and therapeutic interventions, which are currently unavailable for HD. Thus our work is innovative, in our opinion because it represents a new and substantive departure from the status quo, namely the approach of detailing the role of HTT using in vivo dynamics of vesicle movement in a living organism. The proposed research is significant, because it is expected to vertically advance and expand our understanding of how disease pathways initiate, which will significantly alter current knowledge. The knowledge acquired will dramatically propel the development of numerous pharmacological or genetic modifiers against axonal defects or to restore Rab function (impact).