Spatial Regulation of Developmental Gene Expression

描述（由申请人提供）：我们的目标是定义核激素受体如何调节基因组的结构，功能和可及性，以控制产前发育和产后生理中的基因表达。这一提议的基本假设是受体信号是由配体定向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一种暂时的方式调动基因网络来改变细胞的命运、功能和生理。为此，在Aim I中，我们将描述一种独特的肺表型，其中共抑制因子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依赖性转录特征联系起来，该细胞系对甲状腺激素有反应，表达TR和I型标记物。最近大规模平行测序技术的可用性和染色质免疫沉淀方法的进步使得在全基因组范围内确定SMRT和TR的特定基因组位置（池端）成为可能。Aim II将通过对ChIP产品测序并将其定位到参考基因组，确定在T3存在和不存在的情况下MLE-12细胞中的SMRT和TR基质。Aim III将通过绘制MLE-12肺细胞和源自SMRTmRID小鼠的原代培养I型细胞的关键组蛋白乙酰化和甲基化标记，定义肺细胞TR信号传导过程中的表观遗传特征动态。整合Aims I- III的结果将有助于理解特定和重要细胞命运决定的分子密码，并为妊娠晚期肺部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是由于其感染和破坏I型肺细胞。我们的工作和小鼠模型可能为易感人群中I型肺细胞的保护和补充提供新的见解。

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.