Mechanistic Analysis of Parent-of-Origin-Specific Gene Expression in the Placenta

胎盘中亲本特异性基因表达的机制分析

• 批准号: 8714989
• 负责人: Emily Tompkins Maclary
• 金额: $ 3.35万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8714989
• 关键词: Alleles; Biological Models; Cell Line; Cells; Characteristics; Chromatin; Chromosomes; Code; Complex; Data; Development; Embryo; Embryonic Development; Epigenetic Process; Female; Fetal Tissues; Fetus; Fluorescent in Situ Hybridization; Functional RNA; Gases; Gene Expression; Gene Expression Profile; Gene Expression Regulation; Gene Silencing; Genes; Genetic Transcription; Genome; Genomic Imprinting; Genomics; Growth; Hybrids; Inherited; Lead; Link; Mammals; Mediating; Modification; Molecular; Mothers; Mus; Nutrient; Organ; Parents; Placenta; Placentation; Play; Pregnancy; Proteins; RNA; RNA Sequences; Recruitment Activity; Regulation; Reverse Transcriptase Polymerase Chain Reaction; Role; Source; Stem cells; Structure; Testing; Tissues; Transcript; Transcriptional Regulation; Vascularization; Work; X Chromosome; X Inactivation; autosome; catalyst; dosage; embryo tissue; fetal; genome-wide; imprint; in vitro Model; in vivo; insight; instrument; male; mouse model; natural Blastocyst Implantation; next generation; novel; offspring; preimplantation; programs; public health relevance; research study; stem cell population; trophoblast; uptake; wasting

DESCRIPTION (provided by applicant): The placenta is a specialized and essential structure that regulates gas exchange and the transport of nutrients and waste between the mother and the fetus in eutherian mammals. Gene expression in the placenta is tightly controlled, and this finely-tuned gene regulation is a pre-requisite for proper placental development and function. A specialized form of gene regulation known as genomic imprinting is critical for placental function. Genomic imprinting results in the preferential expression of either the maternally- or paternally-inherited allele of a gene. Imprinted genes are hypothesized to regulate the growth rate of fetal tissues, and dysregulation of genomically imprinted loci has been linked to abnormal placental growth and changes in vascularization of the placental tissues. Genomic imprinting in the placenta parallels another intriguing epigenetic process, imprinted X-chromosome inactivation. Imprinted X-inactivation results in the preferential epigenetic silencing of the paternally-inherited inherited X-chromosome in all cells of the early embryo in XX females to equalize the dosage of X-linked genes to that of XY males. While many genomically imprinted loci have been described, how the preferential expression of one allele in a parent-of-origin-specific manner occurs remains poorly understood. Both imprinted X-inactivation and imprinted autosomal gene expression have been linked to long non-coding RNAs (lncRNAs). LncRNAs are non protein-coding transcripts that are hypothesized to recruit chromatin modifying complexes to defined genomic regions, either facilitating transcription or leading to gene silencing during development. Imprinted gene expression relies on differential epigenetic marking in the parental germlines, which is then manifested in expression of one or the other parental allele in the offspring. LncRNA expression can act as an instrument of this differential epigenetic germline marking to establish parent-of-origin-specific gene expression patterns in the embryo. My working hypothesis is that undiscovered lncRNAs trigger regional, parent-of-origin specific epigenetic silencing in the placenta during embryogenesis. Here, I propose to utilize a novel strand- and allele-specific RNA-sequencing approach and a computational pipeline that I have devised in order to identify novel parent-of-origin-specific lncRNAs. I will ue trophoblast stem cells as a source of the RNA. These cells undergo imprinted X- inactivation and also display robust imprinted gene expression on autosomes, and represent an in vitro model of the stem cell population that gives rise to the placenta. Through these experiments, we hope to identify initiators of genomic imprinting in the placenta, and pave the way for further understanding of the molecular mechanisms underlying parent-of-origin specific gene regulation.

描述（由申请人提供）：胎盘是一种特殊且重要的结构，可调节真兽类哺乳动物母亲和胎儿之间的气体交换以及营养物质和废物的运输​​。胎盘中的基因表达受到严格控制，这种微调的基因调控是胎盘正常发育和功能的先决条件。一种称为基因组印记的特殊基因调控形式对于胎盘功能至关重要。基因组印记导致基因的母系或父系遗传等位基因的优先表达。假设印记基因调节胎儿组织的生长速度，基因组印记位点的失调与胎盘生长异常和胎盘组织血管化的变化有关。胎盘中的基因组印记与另一个有趣的表观遗传过程相似，即印记 X 染色体失活。印记X失活导致XX女性早期胚胎所有细胞中父系遗传的X染色体优先表观遗传沉默，从而使X连锁基因的剂量与XY男性的剂量相等。尽管已经描述了许多基因组印记位点，但一个等位基因如何以亲本特异性方式优先表达仍然知之甚少。印记 X 失活和印记常染色体基因表达均与长非编码 RNA (lncRNA) 相关。 LncRNA 是非蛋白质编码转录物，假设其将染色质修饰复合物募集到特定的基因组区域，从而促进转录或导致发育过程中的基因沉默。印记基因表达依赖于亲本种系中的差异表观遗传标记，然后在后代中一个或另一个亲本等位基因的表达中表现出来。 LncRNA 表达可以作为这种差异表观遗传种系标记的工具，以在胚胎中建立亲本特异性基因表达模式。我的工作假设是，未发现的 lncRNA 在胚胎发生过程中触发胎盘中区域性、亲本特异性的表观遗传沉默。在这里，我建议利用我设计的一种新型链和等位基因特异性 RNA 测序方法和计算流程来识别新型亲本特异性 lncRNA。我将使用滋养层干细胞作为 RNA 的来源。这些细胞经历印记X-失活，并且还在常染色体上显示出强大的印记基因表达，并且代表了产生胎盘的干细胞群的体外模型。通过这些实验，我们希望鉴定胎盘中基因组印记的启动子，并为进一步了解亲本特异性基因调控的分子机制铺平道路。