Spatial Regulation of Developmental Gene Expression

描述(申请人提供)：我们的目标是确定核激素受体如何调节基因组的结构、功能和可获得性，以控制产前发育和出生后生理中的基因表达。这一建议的基本假设是，受体信号是由配体指导的染色质修饰介导的，由此产生的诱导或抑制的表观遗传状态以时间的方式动员基因网络来改变细胞的命运、功能和生理。为了做到这一点，在目标I中，我们将描述一种独特的肺表型，在这种表型中，辅阻遏子SMRT破坏甲状腺激素受体(TR)抑制，导致I型肺细胞成熟缺陷导致新生儿死亡。我们将在解剖和细胞水平上将未成熟肺的表型与胎儿和围产期肺以及培养的肺细胞系(MLE-12)中去抑制的TR依赖转录信号相关联，MLE-12细胞系对甲状腺激素有反应，并表达TR和I型标记。最近大规模并行测序技术的出现和染色质免疫沉淀方法的进步使在全基因组范围内确定SMRT和tR的特定基因组位置(Cstrome)成为可能。目的II将通过对芯片产物测序并将其映射到参考基因组来确定在存在和不存在T3的情况下MLE-12细胞中的SMRT和TRcstrome。目的III将通过定位MLE-12肺细胞和来源于SMRTmRID小鼠的原代培养的I型细胞中的关键组蛋白乙酰化和甲基化标记，来确定肺细胞在TR信号转导过程中的表观遗传特征的动态。整合AIMS I-III的结果将有助于理解决定特定和重要细胞命运的分子密码，并为晚期妊娠肺发育和婴儿呼吸系统疾病的预防和治疗提供新的见解。此外，H1N1流感的许多发病率和死亡率都是由于它的感染和I型肺细胞的破坏。我们的工作和小鼠模型可能为易感人群中I型肺泡细胞的保护和补充提供新的见解。 公共卫生相关性：这项建议旨在确定核激素受体如何调节基因组的结构、功能和可获得性，以控制产前发育和新生儿生理中的基因表达。受体调节通路在美国的生育、先天性畸形、早产和呼吸窘迫综合征中尤其相关，这项工作有望为新的诊断和治疗方法的发展提供见解。

DESCRIPTION (provided by applicant): Our goal is to define how nuclear hormone receptors modulate the structure, function and accessibility of the genome to control gene expression in prenatal development and postnatal physiology. The underlying hypothesis of this proposal is that receptor signaling is mediated by ligand-directed chromatin modifications and the resulting induced or repressed epigenetic states mobilize networks of genes in a temporal fashion to alter cell fate, function and physiology. To do this, in Aim I we will characterize a unique lung phenotype in which the disruption of Thyroid Hormone Receptor (TR) repression by the co-repressor SMRT results in neonatal lethality from a maturation defect in type I pneumocytes. We will correlate the immature lung phenotype at the anatomic and cellular level with de-repressed TR-dependent transcriptional signatures in fetal and perinatal lung, and in a cultured pneumocyte cell line (MLE-12) that is thyroid hormone responsive and expresses TR and Type I markers. The recent availability of massively parallel sequencing technology and advances in methods for chromatin immunoprecipitation now makes it possible to determine the specific genomic locations (cistrome) of SMRT and TR on a genome wide scale. Aim II will determine the SMRT and TR cistromes in MLE-12 cells in the presence and absence of T3 by sequencing of ChIP products and mapping these to reference genomes. Aim III will define the dynamics of epigenetic signatures during TR signaling in pneumocytic cells by mapping key histone acetylation and methylation markers in MLE-12 pneumocytes and primary cultured Type I cells derived from SMRTmRID mice. Integration of the results from Aims I- III will aid in understanding the molecular codes that underlie a specific and vital cell fate decision and provide new insights toward late gestational lung development and the prevention and treatment of infant respiratory diseases. In addition, much morbidity and mortality of the H1N1 flu is due to its infection and destruction of the type I pneumocyte. Our work and mouse model may provide new insights into type I pneumocyte protection and replenishment in susceptible human populations. PUBLIC HEALTH RELEVANCE: This proposal is directed at identifying how nuclear hormone receptors modulate the structure, function and accessibility of the genome to control gene expression in prenatal development and neo-natal physiology. Receptor regulated pathways are particularly relevant in fertility, congenital malformations, prematurity, and respiratory distress syndrome in the United States and this work is anticipated to provide insights for the development of new diagnostics and therapeutics.