Lipid kinase regulation of pain signaling and sensitization

描述（由申请人提供）：需要治疗慢性疼痛的新方法，特别是因为现有的镇痛剂具有严重的副作用，并且在治疗炎症性疼痛和神经性疼痛（人类慢性疼痛的两种最常见形式）方面并不总是有效。炎症和神经损伤导致释放一种复杂的化学物质混合物，这些化学物质通过分子多样的感受器（疼痛产生）发出信号。这些受体的激活增加了背根的兴奋性和敏感性 神经节（DRG）和三叉神经节神经元。不幸的是，迄今为止，阻断个体原伤害感受器的努力未能产生对慢性疼痛的有效治疗。在这里，我们提出了一种创新的方法来减少疼痛超敏反应，绕过这个长期存在的问题与受体的多样性。我们的方法是基于选择性地降低DRG神经元中脂质第二信使磷脂酰肌醇4，5-二磷酸（PIP 2）的水平。大多数原伤害感受受体需要PIP 2来启动下游信号传导。此外，许多检测有害刺激的TRP通道和调节膜兴奋性的离子通道都需要PIP 2来激活。因此，PIP 2位于促进和维持慢性疼痛的不同受体、离子通道和信号通路的关键汇聚点。在对小鼠的初步研究中，我们确定了一种脂质激酶，它在DRG神经元中产生至少50%的PIP 2。此外，这种脂质激酶的失活大大降低了对炎症因子的伤害性敏化。基于我们的初步数据，我们假设这种脂质激酶通过PIP 2依赖性机制来调节DRG神经元中的原伤害感受受体信号传导和体内疼痛敏化。为了验证这个假设，我们将：1。使用急性、慢性和自发性疼痛的小鼠模型，包括炎性疼痛和神经性疼痛模型，评价这种脂质激酶在体内调节伤害性致敏的程度。我们将使用一种创新的遗传方法来敲低激酶活性。这种方法选择性地降低DRG中的PIP 2浓度，但不影响处理疼痛信号的其他组织中的PIP 2浓度。我们将使用生化拯救实验进一步评估PIP 2依赖性。2.评估该激酶通过多种原伤害感受受体（包括G蛋白偶联受体、酪氨酸激酶受体和检测伤害性刺激的TRP通道）调节信号传导的程度。3.利用一种新的条件性基因敲除小鼠，诱导删除这种激酶只在成年人的感觉神经元，并评估这种激酶调节炎症性疼痛和神经性疼痛的启动和维持的程度。我们将是第一个严格研究这种激酶在慢性疼痛中的重要性的人。我们的初步数据表明，这种脂质激酶是疼痛信号和致敏的主要调节剂。

DESCRIPTION (provided by applicant): New approaches for treating chronic pain are needed, particularly since existing analgesics have serious side effects and are not always effective at treating inflammatory pain and neuropathic pain-the two most common forms of chronic pain in humans. Inflammation and nerve injury lead to the release of a complex mix of chemicals that signal through molecularly diverse pronociceptive (pain-producing) receptors. Activation of these receptors increases the excitability and sensitivity of nociceptive dorsal root ganglia (DRG) and trigeminal ganglia neurons. Unfortunately, efforts to block individual pronociceptive receptors have so far failed to produce effective treatments for chronic pain. Here, we propose an innovative approach to reduce pain hypersensitivity that bypasses this long-standing problem associated with receptor diversity. Our approach is based on selectively reducing the level of the lipid second messenger phosphatidylinositol 4,5- bisphosphate (PIP2) in DRG neurons. Most pronociceptive receptors require PIP2 to initiate downstream signaling. Moreover, many TRP channels that detect noxious stimuli and ion channels that regulate membrane excitability require PIP2 for activity. PIP2 thus sits at a key convergence point for diverse receptors, ion channels and signaling pathways that promote and maintain chronic pain. In preliminary studies with mice, we identified a lipid kinase that generates at least 50% of all PIP2 in DRG neurons. Moreover, inactivation of this lipid kinase profoundly reduced nociceptive sensitization in response to an inflammatory agent. Based on our preliminary data, we hypothesize that this lipid kinase acts through PIP2 dependent mechanisms to regulate pronociceptive receptor signaling in DRG neurons and pain sensitization in vivo. To test this hypothesis we will: 1. Evaluate the extent to which this lipid kinase regulates nociceptive sensitization in vivo, using mouse models of acute, chronic and spontaneous pain, including models of inflammatory pain and neuropathic pain. We will use an innovative genetic approach to knock-down kinase activity. This approach selectively reduces PIP2 concentration in DRG but does not affect PIP2 concentration in other tissues that process pain signals. We will further evaluate PIP2-dependence using biochemical rescue experiments. 2. Evaluate the extent to which this kinase regulates signaling through diverse pronociceptive receptors, including G protein-coupled receptors, a tyrosine kinase receptor, and TRP channels that detect noxious stimuli. 3. Utilize a new conditional knockout mouse to inducibly delete this kinase only in sensory neurons of adults and to evaluate the extent to which this kinase regulates initiation and maintenance of inflammatory pain and neuropathic pain. We will be the first to rigorously study the importance of this kinase in the setting of chronic pain. Our preliminary data suggest this lipid kinase is a master regulator of pain signaling and sensitization.