Role of P2Y12 and Purinergic Signaling in Microglia-Mediated Synaptic Plasticity

描述(申请人提供)：突触可塑性对正常神经发育和成人回路功能至关重要。最近的证据表明，小胶质细胞在发育突触可塑性中发挥着关键作用，它在神经炎症中是经典的研究对象。 然而，人们对这些角色的驱动机制知之甚少。嘌呤能信号与许多神经发育过程有关，但对小胶质细胞中的嘌呤能信号的研究主要集中在神经炎症作用上。目前尚不清楚嘌呤能信号是否有助于非炎症小胶质细胞的运动，而非炎症小胶质细胞在突触监视和可塑性中起着重要作用。P2Y12是一种嘌呤能受体，与小胶质细胞的运动和 在静息的分枝状小胶质细胞中高度表达。然而，在炎症之后，P2Y12的表达迅速下调，这表明它在健康的神经生理条件下发挥功能。我们认为，P2Y12可能在基础小胶质细胞运动、突触监视和突触可塑性中起关键作用。利用小鼠模型，在目标1中，我们将确定基因或药物干扰P2Y12是否会影响体内基本的小胶质细胞形态或运动性。在目标2中，我们将测试P2Y12中断是否影响小鼠视觉系统中的小胶质突触监视和经验依赖性突触可塑性。此外，在外周巨噬细胞的趋化作用中，P2Y12参与了嘌呤能自分泌系统，这表明在小胶质细胞中可能存在类似的机制。因此，在目标3中，我们将测试小胶质细胞以自分泌方式释放嘌呤是否对突触可塑性中涉及的趋化因子进行有效的趋化是必需的。通过这些研究，我们将探索嘌呤能信号在非炎症小胶质细胞中的新作用。

DESCRIPTION (provided by applicant): Synaptic plasticity is critical for normal neurodevelopment and adult circuit function. Recent evidence suggests that microglia, classically studied in neuroinflammation, play critical roles in developmental synaptic plasticity. However, the mechanisms driving these roles are poorly understood. Purinergic signaling has been implicated in many neurodevelopmental processes, but studies on purinergic signaling in microglia have focused primarily on neuroinflammatory roles. It is unknown whether purinergic signaling contributes to the motility of non-inflamed microglia that underlies roles in synapse surveillance and plasticity. P2Y12 is a purinergic receptor associated with microglial motility and is highly expressed in resting, ramified microglia. However, P2Y12 is rapidly downregulated following inflammation, suggesting that it serves functions under healthy neurophysiological conditions. We propose that P2Y12 may be critical for basal microglial motility, synaptic surveillance, and synaptic plasticity. Using a mouse model, in Aim 1, we will determine whether genetic or pharmacological disruption of P2Y12 affects basal microglial morphology or motility in vivo. In Aim 2, we will test whether P2Y12 disruption affects microglial synaptic surveillance and experience-dependent synaptic plasticity in the mouse visual system. In addition, P2Y12 has been implicated in a purinergic autocrine system in peripheral macrophage chemotaxis, suggesting that a similar mechanism may exist in microglia. Therefore in Aim 3, we will test whether microglial release of purines in an autocrine manner is necessary for efficient chemotaxis towards chemokines implicated in synaptic plasticity. Through these studies, we will explore novel roles for purinergic signaling in non-inflamed microglia.