Dopamine Neuron VGLUT2 Expression in Parkinson's Disease

项目总结 在帕金森病(PD)中，黑质致密部(SNC)中的多巴胺(DA)神经元变性。 相反，腹侧被盖区(VTA)的DA神经元相对受到保护，不受PD诱导的影响 变性，但这种神经保护的原因尚不清楚。一个可能的答案可能来自唯一的 VTA DA神经元的特性：这些细胞的一部分共释放谷氨酸并表达囊泡性谷氨酸 运输机2(VGLUT2)。表达VGLUT2的DA神经元更有可能在神经毒性损伤中存活 在对DA神经毒素有弹性的神经元中观察到PD和DA神经元VGLUT2上调的模型。 值得注意的是，VGLUT2在果蝇、啮齿动物、非人类和 人类灵长类对细胞应激源的反应，表明这是一种进化保守的机制， 提供对DA神经元退化的保护。此外，在果蝇身上，我发现雌性果蝇表达的更多 果蝇VGLUT(DVGLUT)与雄性比较。我还发现，雄性果蝇明显更容易受到DA的影响 在PD的DA神经毒素模型中，与女性相比，神经元变性和表现出更多的运动障碍[例如， 百草枯和6-羟基多巴胺(6OHDA)]类似于人类帕金森病的性别特异性后遗症。这些 研究结果表明，VGLUT2的表达可能是保护这些细胞的调节机制的一部分 这可能会影响帕金森病患者的性别差异。这些数据还表明，遗传上易驯化的苍蝇模型可以 作为一个强大的实验系统来研究DA神经元的弹性和易损性机制 在警局。鉴于VGLUT在DA神经元弹性中的作用，本提案的中心目标是确定：1) DA神经元VGLUT的表达如何影响DA神经元的脆性，2)性别差异在 DA神经元的弹性取决于DA神经元VGLUT表达的差异，以及3)DA神经元如何 VGLUT2在人类帕金森病中的表达变化我将测试DA神经元VGLUT表达的假设 增强对DA神经元的保护，特别是对雌性神经元，因为它们表达更多的VGLUT 与雄性相比。这项提案的长期目标是：1)确定VGLUT在调解中的作用 苍蝇模型中对6OHDA和百草枯反应的脆弱性和性别差异(目标1)，测量 DA神经元VGLUT2在人PD中的表达(目标2)。为了测试这些目标，我将使用RNA干扰来敲打 下调果蝇DA神经元中dVGLUT的表达，并检测雄性与 雌性苍蝇在6OHDA和百草枯PD模型中。同时，我将测量多巴胺神经元VGLUT2在 用死后的人中脑对男性和女性帕金森病患者和匹配的对照组进行人类帕金森病的研究。这些 实验将建立DA神经元VGLUT表达作为帕金森病神经保护的新机制， 导致新的、更有效的治疗方法来预防或减轻帕金森病的DA神经退行性变化。

PROJECT SUMMARY In Parkinson’s Disease (PD), dopamine (DA) neurons degenerate in the substantia nigra pars compacta (SNc). In contrast, the DA neurons of the ventral tegmental area (VTA) are relatively protected from PD-induced degeneration, but the cause of this neuroprotection is unknown. One possible answer may derive from the unique properties of VTA DA neurons: a subset of these cells co-release glutamate and express the vesicular glutamate transporter 2 (VGLUT2). DA neurons that express VGLUT2 are more likely to survive neurotoxic insult in animal models of PD, and DA neuron VGLUT2 upregulation is observed in neurons resilient to DA neurotoxins. Significantly, VGLUT2 expression is upregulated in DA neurons across Drosophila, rodents, non-human and human primates in response to cell stressors, suggesting that this an evolutionarily-conserved mechanism that confers protection against DA neuron degeneration. Moreover, in Drosophila, I discovered females express more Drosophila VGLUT (dVGLUT) compared to males. I also found males flies are markedly more vulnerable to DA neuron degeneration and exhibit more motor deficits compared to females in DA neurotoxin models of PD [e.g., paraquat and 6-hydroxydopamine (6OHDA)] analogous to the sex-specific sequelae of human PD. These findings indicate that VGLUT2 expression is likely part of a regulatory mechanism that may protect these cells and that likely impacts sex differences in PD. These data also show the genetically tractable fly model can be utilized as a powerful experimental system to investigate mechanisms of DA neuron resilience and vulnerability in PD. Given VGLUT’s roles in DA neuron resilience, the central goals of this proposal are to identify: 1) how DA neuron VGLUT expression impacts DA neuron vulnerability, 2) whether the sex differences in DA neuron resilience depend on differences in DA neuron VGLUT expression, and 3) how DA neuron VGLUT2 expression changes in human PD. I will test the hypothesis that DA neuron VGLUT expression confers increased protection in DA neurons, especially in females since they express more VGLUT compared to males. The long-term goals of this proposal are to i) determine the role of VGLUT in mediating vulnerability and sex differences in response to 6OHDA and paraquat in the fly model (Aim 1), and ii), measure DA neuron VGLUT2 expression in human PD (Aim 2). To test these goals, I will use RNA-interference to knock down dVGLUT expression in Drosophila DA neurons, and measure DA neuron vulnerability in male versus female flies in 6OHDA and paraquat PD models. In parallel, I will measure DA neuron VGLUT2 expression in human PD using postmortem human midbrain of both male and female PD patients and matched controls. These experiments will establish DA neuron VGLUT expression as a novel mechanism of neuroprotection in PD, leading to new, more effective therapies to prevent or mitigate the DA neurodegenerative effects of PD.