Molecular Determinants for In vivo Functional Reprogramming of Cortical Output Neurons and Circuits

项目摘要/摘要 目前还没有成功的治疗方法来恢复受损的大脑电路。任何一种引起的神经元丢失 神经退行性疾病或创伤会导致神经和认知功能障碍，对 人类健康。迫切需要找到神经回路修复的策略。直接重编程 这些方法为大脑修复带来了巨大的希望。他们在功能电路恢复方面的成功将取决于他们的 将其他细胞转化为神经元的能力，其功能与电路中受损神经元的功能相匹配。 在小鼠大脑皮层中观察到了这种精确的转换，即皮质输出(皮质醇) 神经元，它可以获得连通性属性，包括长期投影，典型的其他 分离皮质激素亚型。尽管这是朝着电路修复迈出的有希望的一步，但这种精确的转换已经 在胚胎或未成熟状态诱导重编程时观察到。 阻止分化神经元重新编程的机制或保留神经元的机制 终生不变的身份是不被理解的。因此，我们的目标是研究对 在分化的神经元中维持神经元亚型的同一性，并确定它们如何限制重新编程 时间到了。这将揭示阻碍体内神经元亚型之间功能转换的障碍。我们建议 为了研究皮质分离神经元中的这些机制，特别是在体内重新编程的背景下 皮质丘脑神经元(CTN)产生脑下投射神经元(SCN)，这是一种临床相关神经元 肌萎缩侧索硬化症中退化的亚型，其轴突因脊髓损伤而受损。 在这项提案中，我们将研究身份维护机制是否可以在体内被操纵 将CTN重新编程为功能SCN(目标1)，我们将确定这些机制是否可以 在成熟的CTN中灭活，以消除阻碍CTN转变为SCN的障碍(目标2)，我们将 阐明阻止在体内将CTN转化为SCN的潜在下游信号(目标3)。

PROJECT SUMMARY/ABSTRACT Currently there is no successful treatment that restores damaged brain circuitry. Neuron loss by either neurodegenerative diseases or trauma causes neurological and cognitive dysfunction, posing a great burden for human health. There is a critical need to find strategies for neural circuit repair. Direct reprogramming approaches hold great promise for brain repair. Their success in functional circuit restoration will depend on their capacity to convert other cells into neurons with functions matching those of the neurons damaged in a circuit. This precise conversion has been observed in the mouse cerebral cortex between cortical output (corticofugal) neurons, which can acquire the connectivity properties, including long-range projections, typical of other corticofugal subtypes. Though this is a promising step forward toward circuit repair, this precise conversion has been observed when reprogramming is induced at embryonic or immature states. The mechanisms that preclude reprogramming in differentiated neurons or the mechanisms that keep neuron identity unchanged throughout life are not understood. Hence, our goal is to investigate mechanisms critical for maintaining neuron subtype identity in differentiated neurons and determine how they limit reprogramming over time. This will reveal barriers that preclude functional conversion between neuron subtypes in vivo. We propose to investigate these mechanisms in corticofugal neurons, specifically in the context of in vivo reprogramming of Corticothalamic neurons (CTn) to produce Subcerebral projection neurons (SCn), a clinically relevant neuron subtype that degenerates in Amyotrophic lateral sclerosis and whose axons are damaged by spinal cord injury. In this proposal we will investigate whether identity maintenance mechanisms can be manipulated for in vivo reprogramming of CTn into functional SCn (Aim 1), we will determine whether these mechanisms can be inactivated in mature CTn to eliminate barriers that preclude CTn conversion into SCn (Aim 2), and we will elucidate the underlying downstream signals that preclude conversion of CTn into SCn in vivo (Aim 3).