A NOVEL MOLECULAR MECHANISM FOR STIMULATING UTERINE CONTRACTILITY BY OXYTOCIN

催产素刺激子宫收缩的新型分子机制

• 批准号: 9251837
• 负责人: Sarah K. England
• 金额: $ 30.88万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2021-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9251837
• 关键词: Actomyosin; Binding; Biological; Biological Assay; Birth; Calcium Channel; Cell membrane; Cells; Complex; Coupled; Data; Diglycerides; Electrophysiology (science); Event; G-Protein-Coupled Receptors; Goals; Health; Hormones; Human; Inositol; Ion Channel; Knowledge; Life; MYLK gene; Measures; Mediating; Membrane; Membrane Potentials; Modeling; Molecular; Mothers; Mus; Muscle; Myometrial; Myosin Light Chain Kinase; Newborn Infant; Outcome; Oxytocin; Oxytocin Receptor; Pathway interactions; Phosphatidylinositol 4,5-Diphosphate; Phosphatidylinositols; Phospholipase C; Play; Potassium Channel; Pregnancy; Premature Labor; Protein Kinase C; Publishing; Regulation; Reporting; Reproductive Health; Research; Rest; Reverse Transcriptase Polymerase Chain Reaction; Role; Sarcoplasmic Reticulum; Signal Transduction; Smooth Muscle Myocytes; Sodium; Source; Spatial Distribution; Subfamily lentivirinae; System; Testing; Uterine Contraction; Uterus; complement C2a; immunocytochemistry; improved; in vivo; inhibitor/antagonist; knock-down; myometrium; novel; pregnant; premature; pressure; prevent; public health relevance; small hairpin RNA; therapy design; tripolyphosphate; uterine contractility; voltage

 DESCRIPTION (provided by applicant): Proper timing of delivery is important to the immediate and life-long health of both the newborn and the mother, but this event is often mistimed; in the U.S., approximately 12% of babies are born prematurely and up to 10% of pregnancies are described as post-term. For most of pregnancy, the uterus is maintained in a quiescent, non-contractile state in which the myometrial smooth muscle cells (MSMCs) are hyperpolarized, non-excitable, and quiescent. At term, the MSMCs become depolarized, excitable, and contractile. Currently, our limited understanding of how this transition is controlld hampers our ability to treat dysfunctional labor. Numerous ion channels are expressed in the MSMCs and contribute to regulation of uterine excitability. In particular, K+ channels play an important role in maintaining quiescence by controlling MSMC membrane potential by hyperpolarizing the membrane. Another key regulator in control of MSMC excitability is the hormone oxytocin, which binds to the oxytocin receptor (OTR), a Gαq-coupled G-protein coupled receptor (GαqCR). As a result, Protein Kinase C (PKC) is activated and Ca2+ is released from intracellular stores, causing activation of actomyosin contraction. Additionally, it has been proposed that oxytocin triggers Ca2+ influx through voltage-dependent calcium channels by depolarizing the MSMC plasma membrane. However, the molecular mechanism responsible for this depolarization has not been established. Here, we propose to test the central hypothesis that the sodium-activated K+ channel SLO2.1 plays a key role in controlling the resting membrane potential of MSMCs and that its activity is down-regulated at term by either oxytocin-mediated inhibition or decreased expression, resulting in membrane depolarization. Several lines of evidence support this hypothesis. First, our preliminary data indicate that SLO2.1 is expressed in human MSMCs. Second, we report that SLO2.1 activity is modulated by oxytocin in both heterologous systems and MSMCs. Finally, SLO2.1 is known to be regulated by GαqCRs. The goals of this projects are the 1) define the temporal and spatial distribution of SLO2.1 channels in MSMCs, 2) investigate modulation of SLO2.1 channels by oxytocin; and 3) assess the contribution of SLO2.1 channels to regulation of uterine contractility. The research proposed here will establish the molecular pathways that regulate SLO2.1 activity, providing a biological basis for therapies designed to modulate uterine excitability.

 描述（由申请人提供）：正确的分娩时间对于新生儿和母亲的即时和终生健康都很重要，但这一事件往往不合时宜；在美国，大约 12% 的婴儿早产，高达 10% 的妊娠被称为过期妊娠。在怀孕的大部分时间里，子宫维持在静止、非收缩状态，其中子宫肌层平滑肌细胞（MSMC）处于超极化、非兴奋性和静止状态。足月时，MSMC 变得去极化、兴奋和收缩。目前，我们对如何控制这种转变的了解有限，阻碍了我们治疗功能失调的分娩的能力。许多离子通道在 MSMC 中表达，有助于调节子宫兴奋性。特别是，K+ 通道通过超极化膜来控制 MSMC 膜电位，在维持静止方面发挥着重要作用。控制 MSMC 兴奋性的另一个关键调节因子是激素催产素，它与催产素受体 (OTR)（一种 Gαq 偶联 G 蛋白偶联受体 (GαqCR)）结合。结果，蛋白激酶 C (PKC) 被激活，Ca2+ 从细胞内储存中释放，导致肌动球蛋白收缩激活。此外，有人提出，催产素通过使 MSMC 质膜去极化，触发 Ca2+ 通过电压依赖性钙通道流入。然而，导致这种去极化的分子机制尚未确定。在这里，我们建议检验中心假设，即钠激活的 K+ 通道 SLO2.1 在控制 MSMC 的静息膜电位中发挥关键作用，并且其活性在足月时通过催产素介导的抑制或表达减少而下调，导致膜去极化。有几条证据支持这一假设。首先，我们的初步数据表明SLO2.1在人类MSMC中表达。其次，我们报告在异源系统和 MSMC 中 SLO2.1 活性均受到催产素的调节。最后，已知 SLO2.1 受 GαqCR 调节。该项目的目标是 1) 定义 MSMC 中 SLO2.1 通道的时间和空间分布，2) 研究催产素对 SLO2.1 通道的调节； 3) 评估 SLO2.1 通道对子宫收缩力调节的贡献。 这里提出的研究将建立调节 SLO2.1 活性的分子途径，为旨在调节子宫兴奋性的疗法提供生物学基础。