Function and regulation of acid-sensing ion channels in corneal neurons

描述(申请人提供)：伤害性感受，一组感觉神经元通过它来检测伤害性(痛苦)刺激的过程，是支配角膜的三叉神经节神经元中一个重要但知之甚少的过程。这些神经元对一系列刺激性刺激做出反应，包括热、冷、机械力以及包括质子和炎症分子在内的化学物质。角膜中的炎症是由于支配角膜的神经元受损所致，通常会导致这些神经元的敏感化。对伤害性刺激和炎症分子的反应在很大程度上是由离子通道、G蛋白偶联受体(GPCRs)和受体酪氨酸激酶(RTK)介导的。更好地了解参与眼痛的离子通道和痛觉过敏通路对于开发更有针对性的疼痛管理工具将是重要的。这项工作的目的是了解GPCRs和RTK在疼痛转导过程中调节离子通道功能、运输和表达的细胞和分子机制。为此，我将使用酸感离子通道(ASIC)作为一个模型系统，因为它们已被证明在组织酸化时介导疼痛，并且它们在皮肤感觉神经元的炎症过程中受到调节。这些重要的痛觉通道在角膜中的研究很少，尽管角膜神经元对pH的变化表现出强烈的反应。在这项提案中，我计划确定负责检测角膜神经元酸性pH的蛋白质。为了做到这一点，我将学习直接从角膜神经末梢记录。此外，我还将研究激动素和前列腺素等促炎分子对酸敏感电流的影响。许多这些炎性分子触发了磷脂酶c信号通路的激活，从而减少了膜上磷脂酰肌醇PI(4，5)P2的数量。因此，我将研究磷脂酰肌醇在角膜神经元和ASICs调节中所起的作用。

DESCRIPTION (provided by applicant): Nociception, the process through which a subset of sensory neurons detects noxious (painful) stimuli, is an important but poorly understood process in the trigeminal ganglion neurons that innervate the cornea. These neurons respond to a wide array of irritating stimuli including heat, cooling, mechanical force, and chemicals including protons and inflammatory molecules. Inflammation in the cornea, a result of damage to the neurons that innervate it, often leads to sensitization of those neurons. The response to noxious stimuli and to inflammatory molecules is mediated in large part by ion channels, G-protein coupled receptors (GPCRs), and receptor tyrosine kinases (RTKs). A better understanding of the ion channels involved in ocular pain and the hyperalgesic sensory pathway would be important for development of more targeted pain management tools. The goal of this work is to understand the cellular and molecular mechanisms by which GPCRs and RTKs regulate the function, trafficking, and expression of ion channels during pain transduction. To do this, I will use acid-sensing ion channels (ASICs) as a model system because they have been shown to mediate pain in response to tissue acidification and they are regulated during inflammation in cutaneous sensory neurons. These important channels for pain sensation are poorly studied in the cornea despite the fact that corneal neurons display a strong response to changes in pH. In this proposal, I plan to identify the proteins responsible for detection of acidic pH in corneal neurons. To do this I will learn to record directly from corneal nerve terminals. In addition, I wil examine the effects of pro-inflammatory molecules like kinins and prostaglandins of the acid-sensitive currents. Many of these inflammatory molecules trigger the activation of the phospholipase c signaling pathway, which reduces the amount of the phosphoinositide, PI(4,5)P2, in the membrane. Thus, I will examine the role phosphoinositides play in corneal neurons and in the regulation of ASICs.