Gestational Hypoxia and Developmental Plasticity

 描述(由申请人提供)：本提案的总体主题是探索母亲和胎儿适应高海拔长期缺氧的基本机制。此外，我们还将研究从胎儿到成人发育的相关机制。低氧是机体体内平衡机制最常见和最严重的应激之一，妊娠期低氧对母体健康和发育可塑性有深远的不利影响。胎儿和成人对长期缺氧的反应的分子机制尚不清楚。这项建议是一个基础广泛的，多学科的，综合的计划，使用生理学，药理学，细胞，生化和分子方法。基于我们团队25年的研究，我们将在适应高海拔(3801米/12,470英尺)的绵羊上进行研究。我们将检验一些假说。总体假设是，妊娠期间高海拔、长期低氧会导致母亲及其胎儿的系统、细胞和亚细胞反应的表观遗传介导的分子修饰，显著影响发育可塑性和随后的疾病风险。在子宫动脉，我们将验证类固醇激素诱导的动态的、表观遗传介导的DNA甲基化和去甲基化变化在调节大电导钙激活的K通道的表达和功能中起关键作用的假说，在子宫血管适应妊娠和慢性低氧中起关键作用。在脑动脉方面，我们将检验这一假说，即表观遗传相关机制，如DNA甲基化、组蛋白修饰和微RNA，在调节脑动脉α1肾上腺素能受体亚型的表达和功能方面发挥关键作用，以应对发育和慢性缺氧。我们将研究α1受体亚型在交感系统介导的脑血流调节中的作用，以及α甲基化抑制剂、组蛋白修饰和microRNA对常氧和高原低氧胎儿和成年绵羊DNA1受体亚型介导的脑血流调节的影响。此外，我们还将测试一种假说，即慢性低氧总体上会减弱血管的收缩能力，尤其是通过下调肌球蛋白轻链激酶(MLCK)的活性，通过microRNA介导的MLCK消息翻译的减少，增加MLCK蛋白的蛋白酶体降解，以及降低MLCK的特异性活性。最后，我们将验证这一假说，即妊娠低氧改变了调控信号蛋白基因表达模式的分子和表观遗传机制，导致发育中的胎儿和羔羊肾周脂肪组织中棕色脂肪组织的特征/功能重新编程。从科学上讲，这些研究将加深我们对几个重要基因的分子和表观遗传学机制的理解，这些基因包括离子通道、膜受体、关键酶和信号蛋白等在母体和胎儿血管和脂肪组织中对长期缺氧的响应。此外，它们还将阐明成熟发展的一些方面。从临床角度来看，这些研究至少涉及三个重要问题。1)对于胎儿和新生儿，它们与对长期低氧的反应有关，如生活在高海拔地区的妇女，以及吸烟或贫血、患有心脏病或肺病或“胎盘功能不全”的妇女。对于新生儿，它们与脑内出血和肺动脉高压的脑血管血流改变有关。2)这些研究还将有助于理解产妇心血管疾病的机制以及健康和疾病的发展规划。3)最后，在成人中，这些研究与了解疾病的机制有关，包括急性高原反应、先兆子痫以及高原脑和肺水肿。

 DESCRIPTION (provided by applicant): The overall theme of this proposal is to explore fundamental mechanisms whereby the mother and her fetus acclimatize to high altitude, long-term hypoxia. In addition, we will examine the mechanisms in association with development from fetus to adult. Hypoxia is one of the most common and severe stresses to an organism's homeostatic mechanisms and hypoxia during gestation have profound adverse effects on maternal health and developmental plasticity. Much remains unknown of the molecular mechanisms in response to long-term hypoxia in both the fetus and adult. This proposal is a broadly based, multidisciplinary, integrated program using physiological, pharmacological, cellular, biochemical, and molecular approaches. Based on >25 years of research by our group, studies will be conducted in sheep acclimatized to high altitude (3801 m/12,470 ft.). We shall test a number of hypotheses. The overall hypothesis is that high altitude, long-term hypoxia during gestation results in epigenetic-mediated molecular modifications of systemic and cellular and sub-cellular responses in the mother and her fetus, significantly impacting developmental plasticity and the subsequent risk for disease. In uterine arteries, we will test the hypothesis tht steroid hormone-induced dynamic, epigenetic-mediated changes of DNA methylation and demethylation play a key role in regulating expression and function of large- conductance Ca2+-activated K+ channels in uterine vascular adaptation to pregnancy and chronic hypoxia. In cerebral arteries, we will test the hypothesis that epigenetic-related mechanisms such as DNA methylation, histone modifications and microRNA play a key role in regulating expression and function of α1-adrenoceptor subtypes in cerebral arteries in response to development and chronic hypoxia. We will determine the role of α1- adrenoceptor subtypes in sympathetic system-mediated regulation of cerebral blood flow, as well as to examine the effects of inhibitors of DNA methylation, histone modification and microRNA on α1-adrenoceptor subtype- mediated cerebral blood flow regulation in normoxic and high altitude hypoxic fetus and adult sheep. In addition, we will test the hypothesis that chronic hypoxia attenuates vascular contractility in general, and cerebrovascular contractility in particular, through down-regulation of myosin light chain kinase (MLCK) activity via a microRNA- mediated decrease in translation of MLCK message, an increase in proteosomal degradation of MLCK protein, and attenuation of MLCK specific activity. Finally, we will test the hypothesis that gestational hypoxia alters molecular ad epigenetic mechanisms in regulating signaling protein gene expression patterns, resulting in reprogramming of brown adipose tissue characteristics/function in perirenal adipose tissue of the developing fetus and lamb. Scientifically the proposed studies will augment our understanding of molecular and epigenetic mechanisms in regulating the expression and function of several important genes including ion channels, membrane receptors, key enzymes and signaling proteins in maternal and fetal vasculatures and adipose tissue in response to long-term hypoxia. In addition, they will shed light on a number of aspects of maturational development. From a clinical standpoint, these studies relate to at least three important problems. 1) For the fetus and newborn they relate to responses to prolonged hypoxia as occurs in women who live at high altitude, as well as those who smoke or are anemic, who have heart or lung disease, or with "placental insufficiency." For newborn they relate to altered cerebrovascular blood flow with intracerebral hemorrhage and pulmonary hypertension. 2) The studies also will contribute to understanding mechanisms of maternal cardiovascular disorders and developmental "programming" of health and disease. 3) Finally, in the adult the studies are relevant to understanding mechanisms of diseases, including acute mountain sickness, preeclampsia, and high altitude cerebral and pulmonary edema.