Restoring Brain Functions in Alzheimer Models with Interneuron Transplants

描述（由申请人提供）：阿尔茨海默病（AD）导致认知功能恶化和神经元网络活动模式异常，但其潜在机制尚不清楚。我们最近发现，抑制性小清蛋白中间神经元中电压门控钠通道Nav1.1水平的降低对人淀粉样前体蛋白（hAPP）转基因小鼠中神经元网络活动和认知功能的异常有重要贡献（Verret et al.，2012，Cell）。因此，我们建议测试过度的假设，即受损的抑制和改变振荡网络活动有助于突触和网络损伤hAPPJ 20小鼠，并可能在人类AD。该提案将研究一种基于细胞的治疗方法，通过移植基因修饰的胚胎中间神经元前体来增强抑制性中间神经元功能，并减少hAPP小鼠的脑网络和认知异常。来自内侧神经节隆起（MGE）的胚胎前体细胞产生大量Nav1.1阳性抑制性中间神经元。MGE衍生的中间神经元在移植到新生儿或成人宿主脑中时保留显著的迁移和整合能力，在那里它们成熟为功能性和突触活性的抑制性中间神经元。我们的初步数据表明，MGE衍生的抑制性中间神经元逆转了hAPPJ 20小鼠认知和情感领域的行为异常，这表明抑制性功能障碍导致了这些缺陷。有趣的是，过表达Nav1.1的MGE衍生的中间神经元比野生型MGE衍生的中间神经元更有效，这表明可能需要对这些前体进行遗传操作以使它们对hAPP/A？毒性更具抗性。 因此，我们建议通过将具有野生型、高（Nav1.1BAC）和低（Nav1.1R1407X）Nav1.1水平的遗传修饰的胚胎中间神经元前体移植到宿主hAPPJ 20和NTG小鼠中来操纵hAPPJ 20和NTG小鼠中的抑制性细胞活性。我们假设MGE移植将增加hAPPJ 20小鼠中功能性抑制细胞的数量（目标1），改善或恢复抑制性和兴奋性突触活动（目标2），并减少网络异常（目标3）和认知障碍（目标4）。因此，这种基于细胞的治疗方法将针对一种关键细胞类型（PV细胞）和一种关键分子改变（Nav1.1减少），这些细胞类型和分子改变在诱导hAPPJ 20小鼠的网络和认知功能障碍中发挥因果作用。此外，我们还将研究遗传操纵MGE前体的方法，以增强其功能和/或对宿主大脑疾病机制的抵抗力。最初，MGE衍生的抑制性细胞将通过改变Nav1.1水平来操纵，Nav1.1水平严格控制细胞的兴奋性。最后，这种实验方法将使我们能够在不同的宿主小鼠中特异性地操纵抑制性中间神经元，因此，在很大的机制细节中解决抑制功能的网络和细胞自主效应。

DESCRIPTION (provided by applicant): Alzheimer's disease (AD) results in deterioration of cognitive functions and abnormal patterns of neuronal network activity, but the underlying mechanisms are poorly understood. We recently found that reduced levels of the voltage-gated sodium channel Nav1.1 in inhibitory parvalbumin interneurons critically contribute to abnormalities in neuronal network activity and cognitive functions in human amyloid precursor protein (hAPP) transgenic mice (Verret et al., 2012, Cell). Thus, we propose to test the overreaching hypothesis that impaired inhibition and altered oscillatory network activity contribute to synaptic and network impairments in hAPPJ20 mice and possibly in humans with AD. The proposal will investigate a cell-based therapeutic approach to enhanced inhibitory interneuron function and reduce brain network and cognitive abnormalities in hAPP mice by transplanting genetically modified embryonic interneuron precursors. Embryonic precursor cells from the medial ganglionic eminence (MGE) generate large numbers of Nav1.1-postive inhibitory interneurons. MGE-derived interneurons retain a remarkable capacity to migrate and integrate when transplanted into neonatal or adult host brains where they mature into functional and synaptically active inhibitory interneurons. Our preliminary data indicate that MGE-derived inhibitory interneurons reverse behavioral abnormalities in cognitive and emotional domains in hAPPJ20 mice, suggesting that inhibitory dysfunction contributes to these deficits. Interestingly, MGE-derived interneurons overexpressing Nav1.1 were more effective than wildtype MGE-derived interneurons, indicating that genetic manipulations of these precursors might be required to make them more resistant to hAPP/A¿ toxicity. Thus, we propose to manipulate inhibitory cell activity in hAPPJ20 and NTG mice by grafting genetically modified embryonic interneuron precursors with wildtype, high (Nav1.1BAC), and low (Nav1.1R1407X) Nav1.1 levels into host hAPPJ20 and NTG mice. We hypothesize that MGE transplants will increase the number of functional inhibitory cells in hAPPJ20 mice (Aim 1), ameliorate or restore inhibitory and excitatory synaptic activity (Aim 2), and reduce network abnormalities (Aim 3) and cognitive impairments (Aim 4). Thus, this cell- based therapeutic approach will target a key cell type (PV cells) and a key molecular alteration (reduced Nav1.1) that play causal roles in inducing network and cognitive dysfunction in hAPPJ20 mice. In addition, we will investigate approaches to genetically manipulate MGE-precursors to enhance their functions and/or resistance to disease mechanisms of the host brain. Initially, MGE-derived inhibitory cells will be manipulated by altering Nav1.1 levels, which tightly controls cellular excitability. Finally, this experimental approach will allow us to specifically manipulate inhibitory interneurons in different host mice and, therefore, address network and cell-autonomous effects of inhibitory function in great mechanistic detail.