DNA Demethylation and BKca Channel Expression and Function in Uterine Arteries

 描述（由申请人提供）：妊娠期间子宫血流量的显著增加对于胎儿的最佳生长和母亲的心血管健康至关重要。妊娠期子宫胎盘循环的适应不良与临床并发症的高发生率相关，包括先兆子痫和胎儿发育异常。大电导钙激活钾通道（BKCa）在妊娠期子宫血流调节中起着重要作用。最近在绵羊中的研究表明，妊娠和类固醇激素引起BKCa β1亚基显著增加，导致β1：α亚基化学计量增加，子宫动脉中BKCa通道活性升高。然而，分子机制仍然未知。我们的初步研究表明，妊娠和类固醇激素导致β1基因启动子DNA甲基化降低。DNA甲基化是基因表达模式表观遗传抑制的主要机制。最近的研究表明，十-十一易位1-3（TET 1 -3）蛋白在活性DNA去甲基化的强大机制。初步研究表明，妊娠和类固醇激素增加了子宫动脉中TET 1 -2的表达。这些发现导致了一个非常新颖的机制，测试类固醇激素介导的DNA甲基化和去甲基化的动态变化在调节子宫血管适应妊娠的BKCa通道的表达和功能中起着关键作用的假设，建议的研究。两个具体目标将确定：1）类固醇激素介导的启动子去甲基化和BKCa β1基因上调是否在妊娠期子宫动脉中BKCa通道功能增加中发挥因果作用，以及2）类固醇激素介导的TET 1 -3上调是否在妊娠期活性DNA去甲基化和β1基因上调中发挥因果作用。这项研究提出了一个重大突破和范式转移的研究重点，旨在解开高度新颖的表观遗传机制，特别是在子宫血管系统中调节基因表达模式，并在血管平滑肌功能。拟议的研究结果将显着推进我们的知识，子宫胎盘适应妊娠的分子机制，提高我们的理解子宫胎盘循环适应不良和妊娠并发症的病理生理机制。由于BKCa通道功能在调节几乎所有血管床的血管张力和压力中的至关重要性，以及对血管平滑肌中BKCa通道表达和活性的表观遗传调节的极其有限的知识，所提出的研究确实将在生理学和病理生理学中调节BKCa通道活性和血管功能的分子机制的全面理解中产生广泛的影响。

 DESCRIPTION (provided by applicant): The striking increase of uterine blood flow during pregnancy is essential both for optimal growth of the fetus and cardiovascular well-being of the mother. Maladaptation of the uteroplacental circulation during gestation is associated with high incidence of clinical complications including preeclampsia and fetal development abnormality. Large-conductance Ca2+-activated K+ (BKCa) channels play a critical role in regulating uterine blood flow in pregnancy. Recent studies in sheep demonstrated that pregnancy and steroid hormones caused a significant increase in BKCa β1 subunit resulting in increased β1:α subunit stoichiometry and heightened BKCa channel activity in uterine arteries. Yet the molecular mechanisms remain unknown. Our preliminary studies showed that pregnancy and steroid hormones caused a decrease in DNA methylation at the β1 gene promoter. DNA methylation is a chief mechanism in epigenetic repression of gene expression patterns. Recent studies suggest a robust mechanism of ten-eleven translocation 1-3 (TET1-3) proteins in active DNA demethylation. Preliminary studies suggested that pregnancy and steroid hormones increased TET1-2 expression in uterine arteries. These findings lead to the proposed studies of a highly novel mechanism testing the hypothesis that steroid hormone-mediated dynamic changes of DNA methylation and demethylation play a key role in regulating expression and function of BKCa channels in uterine vascular adaptation to pregnancy. Two specific aims will determine whether: 1) steroid hormone-mediated promoter demethylation and BKCa β1 gene up- regulation play a causal role in increased BKCa channel function in uterine arteries in pregnancy, and 2) steroid hormone-mediated up-regulation of TET1-3 plays a causal role in active DNA demethylation and the β1 gene up-regulation in pregnancy. The proposed study presents a major breakthrough and paradigm-shifting focus of research aiming at unraveling highly novel epigenetic mechanisms of hormone-mediated DNA demethylation in regulating gene expression patterns in uterine vasculature in particular, and in vascular smooth muscle function in general. The outcome of the proposed study will significantly advance our knowledge in molecular mechanisms of uteroplacental adaptation to pregnancy and improve our understanding of pathophysiological mechanisms underlying maladaptation of uteroplacental circulation and pregnancy complications. Because of the vital importance of BKCa channel function in regulating vascular tone and pressure in virtually all vascular beds, and the extremely limited knowledge in epigenetic regulation of BKCa channel expression and activity in vascular smooth muscle, the proposed study will indeed have a much broad impact in comprehensive understanding of molecular mechanisms in regulating BKCa channel activity and vascular function in physiology and pathophysiology.