Mechanotransduction in gastrointestinal physiology

项目摘要/摘要 功能性胃肠道疾病(FGID)，如肠易激综合征，影响着大约15%的美国人口。 力的感觉中断，也称为机械感觉，在FGID患者中经常发生。 因此，我的实验室的长期目标是阐明细胞和分子机制 健康人群和FGIDs的胃肠道(GI)机械敏感性有几种机械感觉途径 胃肠道。FGIDs中一个重要的机械感觉通路是神经上皮细胞，它由 一种特殊的感觉上皮肠内分泌细胞(EECS)和内源性或外源性传入神经元。我们 发现了一个亚群的EEC，它们是机械敏感的，表达机械敏感的离子通道， Piezo2。在这些机械敏感的EEC中，Piezo2通道的力驱动激活是必要的 导致细胞内钙离子增加的“受体电流”的产生，信号分子的释放 以及下游的生理效应，如上皮分泌。因此，Piezo2 EEC似乎很重要 上皮性机械传感器，但知识差距限制了我们针对它们的能力。这样做的总体目标是 建议通过测试一种新的假设来确定Piezo2 EECS在胃肠道生理学中的作用 机械敏感的Piezo2 EEC使用钙信号级联将Piezo2的激活与5-羟色胺的释放联系起来 羟色胺和/或GLP-1，从而调节胃肠动力和分泌。我们将在3个具体的例子中检验这一假设 目标。在目标1中，我们将确定精确的机械转导机制，它连接着非常快速的 Piezo2受体电流随着细胞内钙离子的延长而增加，这是释放信号所必需的 分子。在目标2中，我们将根据Gi区和信号转导来确定Piezo2 EEC亚群 它们包含和释放的分子。在目标3中，我们将确定机械敏感的Piezo2 EECs如何调节 机械诱导的胃肠道分泌和收缩。我们建立了新的转基因小鼠模型 我们将追踪、刺激和审问特定的欧洲经济共同体亚群。我们将使用这些老鼠模型 并在一系列创新和成熟的方法中验证了EEC系，从单细胞到体内，再到 确定EEC的机械敏感性功能及其在胃肠道生理学中的作用。这些实验是 从根本上与以前的工作联系在一起，但代表着一个新的令人兴奋的方向，我们能否在 定义的奖励期限。这些研究的结果有望在以下方面取得重大进展： 了解基本的细胞和分子机械转导机制，感觉上皮功能， GI机械生物学，在生理学中具有广泛的翻译价值。对EEC的深刻理解 机械转导使我们能够很好地确定FGID中机械敏感性EECS的变化，从而 我们可能会把它们作为新的和特定的治疗方法。

PROJECT SUMMARY/ABSTRACT Functional gastrointestinal diseases (FGIDs), like irritable bowel syndrome, affect ~15% of the US population. Disruptions in the sensation of forces, also known as mechanosensation, are frequent in patients with FGIDs. Therefore, my laboratory’s long-term goal is to elucidate the cellular and molecular mechanisms of gastrointestinal (GI) mechanosensitivity in health and FGIDs. There are several mechanosensory pathways in the GI tract. One important mechanosensory pathway involved in FGIDs is neuro-epithelial, which is composed of a specialized sensory epithelial enteroendocrine cells (EECs) and intrinsic or extrinsic afferent neurons. We discovered a sub-population EECs which are mechanosensitive and express a mechanosensitive ion channel, Piezo2. In these mechanosensitive EECs, force-driven activation of Piezo2 channels is necessary for generation of “receptor currents” that lead to intracellular Ca2+ increases, the release of signaling molecules and downstream physiologic effects, like epithelial secretion. Thus, Piezo2 EECs appear to be important epithelial mechanosensors, but knowledge gaps limit our ability to target them. The overall objective of this proposal is to determine Piezo2 EECs roles in GI physiology by testing a novel hypothesis that mechanosensitive Piezo2 EECs use a Ca2+ signaling cascade to link Piezo2 activation with release of 5- HT and/or GLP-1 and thereby regulate GI motility and secretion. We will test the hypothesis in 3 Specific Aims. In Aim 1, we will determine the precise mechanotransduction mechanism that connects a very rapid Piezo2 receptor current with prolonged intracellular Ca2+ increase that is necessary for the release of signaling molecules. In Aim 2, we will determine Piezo2 EEC sub-populations based on GI region and the signaling molecules they contain and release. In Aim 3, we will determine how mechanosensitive Piezo2 EECs regulate mechanically induced GI secretion and contractions. We established novel transgenic mouse models that allow us to lineage track, stimulate, and interrogate specific EEC sub-populations. We will use these mouse models and validated EEC lines in a range of innovative and established approaches from single cells to in vivo to determine mechanosensitive EEC functions and their roles in GI physiology. The experiments are foundationally linked to previous work but represent a new and exciting direction and can we can complete in the defined award period. The results from these studies are poised to provide significant advances in the understanding of basic cellular and molecular mechanotransduction mechanisms, sensory epithelial function, GI mechanobiology, and have a broad translational value in physiology. A deep understanding of EEC mechanotransduction positions us well to determine alterations in mechanosensitive EECs in FGIDs, so that we may target them as novel and specific therapies.