Epigenetic Mechanisms in Diabetic Embryopathy

 描述（由申请人提供）：已知母体代谢性疾病会改变宫内环境，并可能导致不良妊娠结局，如出生缺陷。其中最严重的缺陷是神经管缺陷，这种缺陷在孕妇肥胖或糖尿病并发症中更常见。我们在这里提出，暴露于不利的宫内环境影响胚胎发育通过表观遗传机制。这一建议的首要假设是，母体糖尿病诱导组蛋白乙酰化的变化，介导暴露后改变转录反应，从而增加神经管缺陷的风险。我们将通过关注H3 K9和H3 K27乙酰化来验证这一假设，这是活跃基因转录的两个标志。我们建议研究这些染色质修饰在中胚层发育中的作用，我们已经证明，在两个单独的糖尿病妊娠小鼠模型的神经管闭合过程中，这些染色质修饰被破坏。我们的具体目标是：1）确定组蛋白乙酰化的变化对母体高血糖症的转录反应的贡献; 2）在胚胎干细胞分化模型中定义胚胎干细胞分化中胚层发育中诱导的表观遗传变化的作用; 3）研究特定基因组位点处个体染色质标记的“表观遗传编辑”如何影响胚胎干细胞的转录和中胚层分化。这将与光遗传学方法相结合，以实验方式改变体内经历“表观遗传编辑”的小鼠的神经管缺陷风险。在细胞和小鼠中直接操纵特定的染色质修饰在概念上是新颖的，我们建议使用的几种技术是高度创新的。这项研究的长期目标是揭示怀孕期间不良暴露导致出生缺陷的分子机制，并增加以后生活中不良健康结果的可能性。识别有害宫内状况（如糖尿病妊娠）反应中涉及的靶点和途径，对于预防和治疗不利的妊娠结局（如神经管缺陷）具有重要意义。

 DESCRIPTION (provided by applicant): Maternal metabolic diseases are known to alter the intrauterine environment, with potential for unfavorable pregnancy outcomes, such as birth defects. Among the most severe defects are neural tube defects, which occur more frequently in pregnancies complicated by maternal obesity or diabetes. We here propose that exposure to an adverse intrauterine environment affects embryonic development through epigenetic mechanisms. The overarching hypothesis for this proposal is that maternal diabetes induces changes in histone acetylation that mediate altered transcriptional responses after exposure, thereby increasing the risk for neural tube defects. We will test this hypothesis by focusing on H3K9 and H3K27 acetylation, two hallmarks of active gene transcription. We propose to investigate the role of these chromatin modifications in the development of mesoderm, which we have shown to be disrupted during neural tube closure in two separate mouse models of diabetic pregnancy. Our Specific Aims are: 1) Determine the contribution of changes in histone acetylation to transcriptional responses to maternal hyperglycemia; 2) Define the role of exposure-induced epigenetic changes in mesoderm development in an embryonic stem cell differentiation model; 3) Investigate how "epigenetic editing" of individual chromatin marks at specific genomic loci affects transcription and mesoderm differentiation from embryonic stem cells. This will be combined with optogenetic approaches to experimentally modify neural tube defect risk in mice undergoing "epigenetic editing" in vivo. The direct manipulation of specific chromatin modifications in cells and mice is novel in concept, and several technologies we propose to use are highly innovative. The long-term goal of this research is to uncover the molecular mechanisms through which adverse exposures during pregnancy cause birth defects, and increase the potential for adverse health outcomes later in life. Identifying the targets and pathways involved in the response to harmful intrauterine conditions, such as those in diabetic pregnancies, has high significance for the prevention and treatment of unfavorable pregnancy outcomes, such as neural tube defects.