Effects of Hypoxia on Craniofacial Morphology and Molecular Signaling

缺氧对颅面形态和分子信号传导的影响

• 批准号: 8130180
• 负责人: Francis Joel Smith
• 金额: $ 3.62万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8130180
• 关键词: Affect; Age; Alcohols; Apoptosis; Behavior; Binding; Cell Death; Cell Nucleus; Cell Proliferation; Cells; Cephalic; Characteristics; Chick Embryo; Clinical; Congenital Abnormality; Control Groups; Data; Defect; Development; Developmental Delay Disorders; Dose; Electron Transport; Embryo; Embryonic and Fetal Development; Environment; Environmental Risk Factor; Event; Eye; Face; Fetus; Future; Gene Targeting; Genetic; Genetic Transcription; Goals; Half-Life; Holoprosencephaly; Human; Hypoxia; Individual; Life; Mandibulofacial Dysostosis; Mediating; Metabolism; Microforms; Mitochondria; Modeling; Molecular; Morbidity - disease rate; Morphology; Mutation; Neural Crest; Nucleic Acid Regulatory Sequences; Oxidative Stress; Oxygen; Pathway interactions; Pattern; Pharmaceutical Preparations; Pregnancy; Prevention; Process; Production; Prosencephalon; Reactive Oxygen Species; Reporting; Research; Role; SHH gene; Severities; Shapes; Signal Transduction; Staging; Stem cells; Stress; Structure; Survivors; Testing; Therapeutic; Tissues; Twin Multiple Birth; Variant; angiogenesis; base; cell motility; craniofacial; cyclopamine; deprivation; design; disease phenotype; environmental stressor; fetal; fetus hypoxia; human mortality; hypoxia inducible factor 1; insight; loss of function; malformation; mortality; prenatal; prevent; promoter; research study; response; sensor; two-dimensional

DESCRIPTION (provided by applicant): Craniofacial malformations can arise from genetic causes and/or environmental factors, including hypoxia in pregnancy. To understand the mechanisms underlying craniofacial malformations induced by hypoxia, I have designed a hypoxic chick embryo model by decreasing the level of oxygen in ovo. To test the correlation between hypoxia and craniofacial malformations, I will examine the role of developmental morphogenetic signaling and the cellular response to hypoxia via the hypoxia-inducible factor-1 (HIF-1) pathway and reactive oxygen species (ROS). Inspired by a recent clinical report of holoprosencephalic anomalies in an acardiac human twin fetus that was hypoxic, my preliminary studies demonstrate that hypoxia reduces survival and delays development in chick embryos, disrupts cell proliferation, and alters facial morphology. Hypoxia led to a roughly dose-dependent decrease in survival with increasing hypoxia, and the severity of developmental delay decreased with the age of survivors (ie, fewer survivors with more severe delay). Hypoxic embryos also showed a spectrum of cephalic and craniofacial malformations ranging from mild asymmetry and eye defects to more severe defects in frontonasal structures and exposed cephalic tissues, characteristic of holoprosencephaly. 2-dimensional geometric morphometrics showed significant abnormal facial shape variation in relation to centroid size and age, among individuals in hypoxic vs. normoxic control groups, and among hypoxic groups compared to the normoxic group. The morphometric data indicate that hypoxia leads to severe developmental delay, and to a lesser degree, malformations in embryos that are able to survive the hypoxic insult. Hypoxia disrupted cell proliferation. In early stages of development, apoptosis of neural crest progenitor cells was observed in varying degrees. How hypoxia causes craniofacial malformations is not understood. I hypothesize that hypoxia creates abnormal craniofacial morphology via Hif-11-mediated apoptosis and by decreased cell proliferation due to altered molecular signaling between the forebrain and frontonasal process. To test my hypothesis, I will determine the extent to which hypoxia generates significant morphological alterations by altering cell proliferation, cell death and molecular changes. In addition, I will undertake gain- and loss-of-function studies to define the relationship of hypoxia-adaptive molecular signaling to malformations. In my two Specific Aims, I will uncover the possible cellular and molecular mechanisms underlying malformations due to hypoxia, as well as the role of HIF-1 and ROS activity in cells under hypoxic stress. In Aim 1, I will determine the extent to which cellular and molecular changes due to hypoxia cause facial malformations that resemble holoprosencephaly, by quantifying changes in facial morphology and relating these changes to cellular behavior and molecular signaling; this will test directly the hypothesis that hypoxia produces holoprosencephaly. In Aim 2, I will test the relationship between HIF-11, ROS, and facial malformations, by assessing the extent to which HIF-11 is necessary and sufficient to cause defects resulting from hypoxia and by testing the hypothesis that the hypoxia sensor, ROS production by the electron transport chain in hypoxia, can be targeted to reduce mortality rates and reverse malformations. My findings will provide insights into how craniofacial malformations caused by hypoxia can be prevented and reversed with future therapeutic strategies. PUBLIC HEALTH RELEVANCE: How can an environmental stressor, such as oxygen deprivation, affect the development of craniofacial structures in the embryo? Answering this question is important for the prevention and treatment of craniofacial birth defects that at least partially arise from environmental stresses including the lack of oxygen during embryonic and fetal development, as well as for devising new therapies to reverse these malformations. This project aims to identify the cellular and molecular events that create craniofacial defects in a low-oxygen environment.

描述(申请人提供)：颅面畸形可由遗传原因和/或环境因素引起，包括怀孕期间的缺氧。为了了解低氧导致颅面畸形的机制，我设计了一个通过降低卵子中氧气水平的低氧鸡胚胎模型。为了测试低氧与颅面畸形的相关性，我将通过低氧诱导因子-1(HIF-1)途径和活性氧(ROS)来研究发育形态发生信号的作用以及细胞对低氧的反应。受最近一份关于缺氧的无心双胞胎全前脑异常的临床报告的启发，我的初步研究表明，缺氧降低了鸡胚胎的存活率和发育，扰乱了细胞增殖，并改变了面部形态。低氧导致存活率随低氧程度的增加而大致呈剂量依赖性下降，发育迟缓的严重程度随存活年龄的增加而降低(即存活的人越少，发育迟缓越严重)。低氧胚胎还显示出一系列头面部畸形，从轻微的不对称和眼睛缺陷到额鼻结构和暴露的头部组织的更严重缺陷，这是全前脑畸形的特征。二维几何形态计量学结果显示，低氧组与常氧组之间、缺氧组与常氧组之间、缺氧组与常氧组之间的面部形态与质心大小和年龄均有显著差异。形态计量学数据表明，低氧会导致严重的发育延迟，并在较小程度上导致能够在低氧侮辱中存活的胚胎畸形。低氧干扰了细胞的增殖。在发育早期，神经脊祖细胞出现不同程度的凋亡。目前尚不清楚缺氧是如何导致颅面畸形的。我假设缺氧通过Hif-11介导的细胞凋亡和由于前脑和额鼻突之间的分子信号改变而导致的细胞增殖减少而造成异常的头面部形态。为了验证我的假设，我将确定低氧在多大程度上通过改变细胞增殖、细胞死亡和分子变化来产生显著的形态变化。此外，我还将进行获得和丧失功能的研究，以确定低氧适应分子信号与畸形的关系。在我的两个具体目标中，我将揭示缺氧导致畸形的可能的细胞和分子机制，以及缺氧应激下细胞中HIF-1和ROS活性的作用。在目标1中，我将通过量化面部形态的变化，并将这些变化与细胞行为和分子信号联系起来，确定由于低氧导致的细胞和分子变化导致类似于全前脑的面部畸形的程度；这将直接检验低氧导致全前脑畸形的假设。在目标2中，我将测试HIF-11、ROS和面部畸形之间的关系，方法是评估HIF-11对造成缺氧引起的缺陷的必要性和充分性，并测试缺氧传感器的假设，即缺氧时电子传输链产生的ROS可以靶向降低死亡率和逆转畸形。我的发现将为如何通过未来的治疗策略预防和扭转缺氧引起的颅面畸形提供见解。 公共卫生相关性：环境应激源，如缺氧，如何影响胚胎头面部结构的发育？回答这个问题对于预防和治疗至少部分由环境应激引起的颅面部出生缺陷，包括胚胎和胎儿发育期间的缺氧，以及设计新的治疗方法来逆转这些畸形都是重要的。该项目旨在确定在低氧环境中造成头面部缺陷的细胞和分子事件。