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

描述（由申请人提供）：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，经典的神经炎症研究，在发育突触可塑性中发挥关键作用。 然而，驱动这些作用的机制知之甚少。嘌呤能信号转导参与了许多神经发育过程，但对小胶质细胞中嘌呤能信号转导的研究主要集中在神经炎症作用上。目前还不清楚嘌呤能信号是否有助于非炎症小胶质细胞的运动，在突触监视和可塑性的基础作用。P2Y12是与小胶质细胞运动相关的嘌呤能受体， 在静息的分枝小胶质细胞中高度表达。然而，P2Y12在炎症后迅速下调，表明它在健康的神经生理条件下发挥作用。我们建议，P2Y12可能是至关重要的基础小胶质细胞的运动，突触监督，和突触可塑性。使用小鼠模型，在目标1中，我们将确定P2Y12的遗传或药理学破坏是否影响体内基底小胶质细胞形态或运动性。在目标2中，我们将测试P2Y12中断是否影响小胶质细胞突触监视和小鼠视觉系统中的经验依赖性突触可塑性。此外，P2Y12还参与外周巨噬细胞趋化性中的嘌呤能自分泌系统，表明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是对突触可塑性中涉及的趋化因子的有效趋化所必需的。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.