Prevention of HPE in a mouse model susceptible to retinoic acid teratogenicity

描述（由申请人提供）：在颅面缺损发病机制中，基因-环境相互作用机制的理解存在根本性的空白。这种差距的存在阻碍了我们预防高危个体缺陷的能力。我们的长期目标是了解使患者易患颅面缺损的潜在机制，以便设计有针对性的预防干预措施。扭曲原肠胚形成（TWSG1）缺失的小鼠模型使我们能够研究这些相互作用的潜在机制，因为TWSG1 -/-小鼠表现出低外显率的HPE，约为17%，在暴露于亚致畸剂量的维甲酸（RA）后增加到100%。本研究的目的是表征twsg1缺陷小鼠对ra诱导的HPE易感性增加的机制。核心假设是，在Twsg1突变体中，骨形态发生蛋白（BMP）信号的失调降低了凋亡阈值，使胚胎对RA的致畸作用敏感。破坏细胞凋亡通路有望保护胚胎。使用这个模型的基本原理是，环境因素，不像遗传畸变，在人类中是可以改变的，只要潜在的机制可以被确定。基于我们的初步数据，我们将通过追求三个具体目标来验证中心假设：1)检查子宫内RA暴露对Twsg1突变胚胎中控制神经和面部中线发育的分子程序的影响；2)研究RA暴露对Twsg1突变胚胎中BMP信号传导和HPE表型背后的细胞过程的影响；3)了解氧化应激和p53激活在介导BMP/RA效应中的作用及其作为HPE预防靶点的潜力。该研究提出了一个新的概念，即BMP通路可能调节胚胎对环境损伤（如RA）的易感性。此外，本研究开始解决目前知之甚少的p53信号在发育中的作用。最后，该项目寻求发展的预防性干预措施可能对当前的临床实践产生影响。本研究的预期结果是：1)阐明HPE发病机制中基因-环境相互作用的机制，特别是低外显率突变如何使胚胎对环境致畸物敏感；2)加深对BMP和RA信号相互作用的理解；3)对氧化应激和p53激活在HPE中的作用的认识增加；4)建立胚胎致畸物预防干预措施检测模式。这些结果有望对颅面缺损的预防产生重要的积极影响。

DESCRIPTION (provided by applicant): There is a fundamental gap in understanding the mechanisms of gene-environment interactions in the pathogenesis of craniofacial defects. The existence of this gap hinders our ability to prevent defects in at risk individuals. Our long-term goal is to understand the underlying mechanisms that predispose patients to craniofacial defects in order to design targeted preventive interventions. A mouse model deficient in Twisted gastrulation (TWSG1) allows us to study the underlying mechanisms of these interactions because Twsg1-/- mice manifest HPE with a low penetrance of about 17%, which increases to 100% after exposure to subteratogenic doses of the retinoic acid (RA). The objective of this study is to characterize the mechanisms of increased susceptibility of TWSG1-deficient mice to RA-induced HPE. The central hypothesis is that dysregulation of bone morphogenetic protein (BMP) signaling in Twsg1 mutants reduces an apoptotic threshold, sensitizing the embryos to teratogenic effects of RA. Disrupting apoptotic pathways would be expected to be embryo-protective. The rationale for using this model is that environmental factors, unlike genetic aberrations, are modifiable in humans as long as the underlying mechanisms can be identified. Based on our preliminary data, the central hypothesis will be tested by pursuing three specific aims: 1) to examine the effects of in utero RA exposure on the molecular program that governs neural and midline facial development in Twsg1 mutant embryos; 2) to examine the impact of RA exposure on BMP signaling and cellular processes underlying the HPE phenotype in Twsg1 mutant embryos; 3) to understand the role of oxidative stress and p53 activation in mediating BMP/RA effects and their potential as targets for HPE prevention. The proposed research presents a novel concept that the BMP pathway may regulate embryonic susceptibility to environmental insults, such as RA. In addition, this study begins to address the role of p53 signaling in development, which is currently poorly understood. Finally, the preventive interventions that this project seeks to develop may have an impact on the current clinical practice. The expected outcomes of this study are: 1) elucidation of the mechanisms of gene-environment interactions in the pathogenesis of HPE, specifically how mutations with low penetrance can sensitize the embryos to environmental teratogens; 2) improved understanding of the interactions between BMP and RA signaling; 3) enhanced knowledge about the roles of the oxidative stress and p53 activation in HPE; and 4) establishment of a model for testing preventive interventions for embryonic teratogens. Such results are expected to have an important positive impact on prevention of craniofacial defects.