Uterine Arterial Spontaneous Transient Outward Currents in Pregnancy

项目总结 妊娠期子宫血流量显著增加的子宫血管适应对 胎儿发育以及母亲的心血管健康。虽然血管扩张是 在子宫循环适应妊娠中的关键作用，潜在的机制并不是 完全理解。生理膜电位()时的自发瞬时外向电流(STOC) 30-40 mV)，从根本上调节血管肌张力和血流量 在器官中，以及动脉压。我们对绵羊的初步研究表明，怀孕 子宫动脉平滑肌细胞STOCs显著增加，确定了一个令人兴奋的调控靶点 在妊娠期子宫血管适应中。STOCs主要由大电导钙离子介导。 激活K(BKCa)通道。血管平滑肌中的BKCa通道含有通道形成 亚基和最多四个辅助β-1亚基通过兰诺定的开放来感知钙火花 感受器。我们先前的研究表明BKβ1亚单位的表达显著上调。 导致妊娠动物子宫动脉β1：亚单位化学计量比增加。这是因为 子宫动脉中BKβ1亚单位基因启动子甲基化减少。动态调节 DNA甲基化和去甲基化是基因表达的表观遗传修饰的主要机制 模式和生物功能。最近的研究表明，10-11是一种强大的机制 转位1-3(TET1-3)蛋白通过将5-甲基胞嘧啶(5mC)转化为 5-羟甲基胞嘧啶(5hmC)。我们的初步研究表明，怀孕和类固醇激素 子宫组织中BKβ1启动子TET1和TET2的表达及5hmC丰度显著增加 动脉，提示激素介导的子宫内活性DNA去甲基化的一种高度新的机制 血管对怀孕的适应。此外，初步数据表明，怀孕会导致 Ryanodine受体介导的子宫动脉钙火花显著增加。有了这些令人兴奋的东西 发现和许多高度新颖的线索，我们现在的定位是在一个 通过启动一个新的研究重点，旨在了解分子和表观遗传学 STOCs调控机制在子宫动脉血管扩张中的重要作用 在怀孕期间。因此，这项拟议的研究将检验怀孕上调BKβ1的假设 Tet介导的DNA去甲基化亚基表达及增加兰尼定受体诱导的钙离子浓度 火花，导致子宫血管适应妊娠的STOCs增加。其结果是 拟议的研究将为子宫胎盘适应的分子机制提供新的见解 妊娠，并将对我们理解 妊娠并发症，包括先兆子痫和胎儿生长受限，由适应不良引起 子宫胎盘循环。鉴于STOCs在调节血管张力和 几乎所有血管床上的压力，揭示了血管平滑中STOCs功能的表观遗传调节 肌肉确实会对分子的全面理解产生更广泛的影响 血管生理学和病理生理学的机制。

PROJECT SUMMARY Uterine vascular adaptation with the striking increase of uterine blood flow during gestation is essential for fetal development as well as for cardiovascular well-being of the mother. Although vasodilatation is of critical importance in the adaptation of uterine circulation to pregnancy, the underlying mechanisms are not fully understood. Spontaneous transient outward currents (STOCs) at physiological membrane potentials ( 30-40 mV) of vascular smooth muscle cells fundamentally regulate vascular myogenic tone and blood flow in an organ, as well as arterial pressure. Our preliminary studies in sheep revealed that pregnancy significantly increased STOCs in uterine arterial smooth muscle cells, identifing an exciting regulatory target in uterine vascular adaptation in gestation. STOCs are mainly mediated by large-conductance Ca2+- activated K (BKca) channels. The BKca channel in vascular smooth muscle contains the channel-forming  + subunit and up to four accessory β1 subunits that sense Ca2+ sparks via the opening of ryanodine receptors. Our previous studies demonstrated a significant upregulation of BKβ1 subunit expression, resulting in increased β1: subunit stoichiometry in uterine arteries of pregnant animals. This resulted from a decrease in promoter methylation of the BKβ1 subunit gene in uterine arteries. Dynamic regulation of DNA methylation and demethylation is a chief mechanism in epigenetic modifications of gene expression pattern and biological function. Recent studies have suggested a robust mechanism of ten-eleven translocation 1-3 (TET1-3) proteins in active DNA demethylation by converting 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC). Our preliminary studies showed that pregnancy and steroid hormones significantly increased TET1 and TET2 expression and 5hmC abundance at the BKβ1 promoter in uterine arteries, suggesting a highly novel mechanism of hormone-mediated active DNA demethylation in uterine vascular adaptation to pregnancy. In addition, the preliminary data suggested that pregnancy resulted in a significant increase in Ca2+ sparks mediated by ryanodine receptors in uterine arteries. With these exciting findings and many highly novel leads, we are now positioned to move the field forward significantly in a manner by launching a new focus of research aiming at the understanding of molecular and epigenetic mechanisms in the regulation of STOCs that are of fundamental importance in uterine arterial vasodilatation during gestation. Thus, the proposed study will test the hypothesis that pregnancy upregulates BKβ1 subunit expression via TET-mediated DNA demethylation and increases ryanodine receptor-induced Ca2+ sparks, resulting in heightened STOCs in uterine vascular adaptation to pregnancy. The outcome of proposed study will provide novel insights in molecular mechanisms of uteroplacental adaptation to pregnancy, and will have a major impact in our understanding of pathophysiologic mechanisms underlying pregnancy complications including preeclampsia and fetal growth restriction, caused by maladaptation of uteroplacental circulation. Given that STOCs are fundamentally important in regulating vascular tone and pressure in virtually all vascular beds, revealing epigenetic regulation of STOCs function in vascular smooth muscle will indeed have a much broader impact in the comprehensive understanding of molecular mechanisms in vascular physiology and pathophysiology.