Analysis Of Imprinting On Mouse Distal Chromosome 7

小鼠远端染色体 7 上的印记分析

基本信息

批准号：
7734744
负责人：
Karl Eric Pfeifer
金额：
$ 71.68万
依托单位：
EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/7734744
关键词：
11p15.5 Address Adrenergic Agents Affect Alleles Animals Area Arrhythmia Beckwith-Wiedemann Syndrome Behavior Biological Models Biological Process Calcium Calsequestrin Cardiac Cardiac Myocytes Cell Nucleus Chromatin Structure Chromosomes Chromosomes, Human, Pair 7 Clinical Complex Condition DNA Modification Process Defect Development Developmental Process Disease Disruption Distal EKG P Wave Elements Epigenetic Process Etiology Fathers Gene Cluster Gene Expression Gene Mutation Genes Genetic Genetic Enhancer Element Genetic Transcription Genomics Goals Growth and Development function H19 gene Heart Human Inheritance Patterns Inherited Insertional Mutagenesis Ion Channel Late Effects Long QT Syndrome Mammals Maps Methylation Modeling Molecular Morphology Mothers Mus Mutation Nephroblastoma Parents Pattern Phenotype Proteins Range Regulation Research Role Sarcoplasmic Reticulum Signal Transduction Structure Surface Testing Transcriptional Silencer Elements adrenergic base cancer type cell growth developmental disease gene function genetic analysis human disease imprint in vivo mouse model programs promoter research study restoration transcription factor

项目摘要

Imprinting represents a curious defiance of normal Mendelian genetics. Mammals inherit two complete sets of chromosomes, one from the mother and one from the father, and most autosomal genes will be expressed equally from maternal and paternal alleles. Imprinted genes, however, are expressed from only one chromosome in a parent-of-origin dependent manner. Because silent and active promoters are present in a single nucleus, the differences in activity cannot be explained by transcription factor abundance. Thus the transcriptional of imprinted genes represents a clear situation in which epigenetic mechanisms restrict gene expression. Therefore imprinted genes are good models for understanding the role of DNA modifications and chromatin structure in maintaining appropriate patterns of gene expression. Further, because of parent-of-origin restricted expression, phenotypes determined by imprinted genes are not only susceptible to mutations of the genes themselves but also to disruptions in the epigenetic programs controlling regulation. Thus imprinted genes are frequently associated with human diseases, including disorders affecting cell growth, development, and behavior. Our Section is investigating a cluster of genes on the distal end of mouse chromosome 7. The syntenic region in humans on chromosome 11p15.5 is conserved in genomic organization and in monoallelic expression patterns. Specifically we are dissecting the molecular basis for the maternal specific expression of the H19 gene and the paternal specific expression of the Igf2 gene. Loss of imprinting mutations in these two genes is associated with Beckwith Wiedemann Syndrome (BWS) and with Wilms tumor. Expression of both H19 and Igf2 is dependent upon a shared set of enhancer elements downstream of both genes. We have identified a 2.4 kb ICR (for Imprinting Control Region) upstream of the H19 promoter. Using conditional deletion and insertional mutagenesis we have identified three functions associated with this element. First, this element acts to distinguish the parental origin of any chromosome into which it is inserted. Specifically, the CpGs within this region become hypermethylated upon paternal inheritance. Second, this element functions as a CTCF-dependent, methylation-sensitive transcriptional insulator. By reorganizing the long-range interactions of nearby promoter and enhancer elements, this insulator is able to direct parental-specific activation of nearby genes. Finally, this ICR also acts as a developmentally regulated silencer element when paternally inherited. Specifically, the methylated ICR induces changes in chromatin structure of neighboring sequences that impacts gene expression. Our current goals are to identify and characterize the protein factors that interact with the ICR and establish the chromatin structures associated with the maternal and paternal chromosomes. A second focus of our research is to generate mouse models for cardiac arrhythmias. We first focused on uncovering the biological function of the imprinted Kcnq1 gene, located just upstream of Igf2. Kcnq1 has been identified independently by groups looking for genes important in the etiology of BWS, a disease with parent-of-origin inheritance patterns, and for genes important in Long QT syndromes (LQTS) mapping to 11p15.5, a disease with no parent-of-origin effects. We have elucidated the complex developmental regulation of imprinting of this gene so to resolve this apparent paradox. Recently, we have developed a model for inherited LQTS by generating mice deficient in Kcnq1. In vivo ECGs from these mice show abnormal T-wave and P-wave morphologies and prolongation of the QT and JT intervals. However, ECGs of isolated hearts are normal. These changes are indicative of cardiac repolarization defects that are dependent upon some extracardiac signal. Further studies demonstrate that beta-adrenergic stimulation is the primary extracardiac signal and the molecular basis for this effect is being dissected. More recently, we have generated a mouse model for Calsequestrin2 deficiency. We demonstrate that calsequestrin2 is not essential for cardiac calcium storage, which can be maintained by an expansion of the sarcoplasmic reticulum (SR) volume and surface area. Rather, the primary function of calsequestrin appears to be the regulation of the SR Ca2 release channel during conditions of beta-adrenergic stimulation. The loss of calsequestrin2 thus results in premature Ca2 release from the SR, leading to premature contraction of cardiomyocytes, and arrhythmia. We have recently generated and are now analyzing conditional alleles of calsequestrin 2. Using these models we will analyze the effect of late-onset loss of calsequestrin 2 gene function, thus modeling a common human condition. We will also determine the effect of restoration of calsequestrin 2 gene function to animals that have developed in the absence of any active calsequestrin 2 gene. Together these experiments will also help us understand how calsequestin 2 gene activity regulates sarcoplasmic reticulum structure.

印记代表了对正常孟德尔遗传学的一种奇怪的蔑视。哺乳动物继承了两套完整的染色体，一套来自母亲，一套来自父亲，大多数常染色体基因将在母本和父本等位基因中同等表达。然而，印记基因仅从一条染色体以依赖于亲本的方式表达。由于沉默启动子和活性启动子存在于单个核中，因此活性差异不能用转录因子丰度来解释。因此，印记基因的转录代表了表观遗传机制限制基因表达的明显情况。因此，印记基因是了解 DNA 修饰和染色质结构在维持适当的基因表达模式中的作用的良好模型。此外，由于亲本表达受到限制，由印记基因决定的表型不仅容易受到基因本身突变的影响，而且还容易受到控制调节的表观遗传程序的破坏。因此，印记基因经常与人类疾病相关，包括影响细胞生长、发育和行为的疾病。我们的部门正在研究小鼠 7 号染色体远端的一组基因。人类 11p15.5 号染色体上的同线性区域在基因组组织和单等位基因表达模式中是保守的。具体来说，我们正在剖析 H19 基因的母体特异性表达和 Igf2 基因的父体特异性表达的分子基础。这两个基因中印记突变的缺失与贝克威斯·维德曼综合征 (BWS) 和肾母细胞瘤有关。 H19 和 Igf2 的表达取决于两个基因下游的一组共享增强子元件。我们在 H19 启动子上游鉴定了一个 2.4 kb ICR（印记控制区）。使用条件删除和插入诱变，我们已经确定了与该元件相关的三个功能。首先，该元件的作用是区分其所插入的任何染色体的亲本起源。具体来说，该区域内的 CpG 在父系遗传后变得高度甲基化。其次，该元件作为 CTCF 依赖性、甲基化敏感的转录绝缘子发挥作用。通过重组附近启动子和增强子元件的长程相互作用，该绝缘体能够指导附近基因的亲本特异性激活。最后，当父系遗传时，该 ICR 还充当发育调节的沉默元件。具体来说，甲基化的 ICR 会诱导邻近序列的染色质结构发生变化，从而影响基因表达。我们当前的目标是识别和表征与 ICR 相互作用的蛋白质因子，并建立与母本和父本染色体相关的染色质结构。我们研究的第二个重点是生成心律失常的小鼠模型。我们首先关注于揭示位于 Igf2 上游的印记 Kcnq1 基因的生物学功能。 Kcnq1 已由寻找 BWS（一种具有亲本遗传模式的疾病）病因学中重要基因以及映射到 11p15.5（一种无亲本疾病）的长 QT 综合征 (LQTS) 中重要基因的小组独立鉴定。原产地效应。我们已经阐明了该基因印记的复杂发育调控，从而解决了这一明显的悖论。最近，我们通过生成 Kcnq1 缺陷的小鼠开发了遗传性 LQTS 模型。这些小鼠的体内心电图显示异常的 T 波和 P 波形态以及 QT 和 JT 间期延长。然而，离体心脏的心电图是正常的。这些变化表明依赖于某些心外信号的心脏复极缺陷。进一步的研究表明，β-肾上腺素能刺激是主要的心外信号，并且正在剖析这种效应的分子基础。最近，我们建立了 Calsequestrin2 缺乏症小鼠模型。我们证明 calsequestrin2 对于心脏钙储存不是必需的，可以通过扩大肌浆网 (SR) 体积和表面积来维持心脏钙储存。相反，calsequestrin 的主要功能似乎是在 β-肾上腺素能刺激条件下调节 SR Ca2 释放通道。因此，calsequestrin2 的缺失会导致 SR 中的 Ca2 过早释放，从而导致心肌细胞过早收缩和心律失常。我们最近生成并正在分析 calsequestrin 2 的条件等位基因。使用这些模型，我们将分析晚发性 calsequestrin 2 基因功能丧失的影响，从而模拟常见的人类状况。我们还将确定恢复 calsequestrin 2 基因功能对在缺乏任何活性 calsequestrin 2 基因的情况下发育的动物的影响。这些实验还将帮助我们了解 calsequestin 2 基因活性如何调节肌浆网结构。

项目成果

期刊论文数量（13）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Analysis of the H19ICR insulator.

H19ICR 绝缘子分析。

DOI：
发表时间：
2007-05
期刊：
影响因子：
5.3
作者：
Yoon, Young Soo;Jeong, Sangkyun;Rong, Qi;Park, Kye;Chung, Jae Hoon;Pfeifer, Karl
通讯作者：
Pfeifer, Karl

Imprint control element-mediated secondary methylation imprints at the Igf2/H19 locus.

印记控制元件介导的 Igf2/H19 基因座的二次甲基化印记。

DOI：
发表时间：
2003-02-21
期刊：
影响因子：
0
作者：
Srivastava, Madhulika;Frolova, Ella;Rottinghaus, Brian;Boe, Steven P;Grinberg, Alexander;Lee, Eric;Love, Paul E;Pfeifer, Karl
通讯作者：
Pfeifer, Karl

A transcriptional insulator at the imprinted H19/Igf2 locus.

印记 H19/Igf2 基因座上的转录绝缘子。

DOI：
10.1101/gad.14.15.1908
发表时间：
2000-08-01
期刊：
Genes & development
影响因子：
10.5
作者：
C. R. Kaffer;M. Srivastava;K. Park;E. Ives;S. Hsieh;J. Batlle;A. Grinberg;S. Huang;K. Pfeifer
通讯作者：
K. Pfeifer

Targeted disruption of the Kcnq1 gene produces a mouse model of Jervell and Lange-Nielsen Syndrome.

Kcnq1 基因的靶向破坏产生了 Jervell 和 Lange-Nielsen 综合征的小鼠模型。

DOI：
发表时间：
2001-02-27
期刊：
影响因子：
11.1
作者：
Casimiro, M C;Knollmann, B C;Ebert, S N;Vary Jr, J C;Greene, A E;Franz, M R;Grinberg, A;Huang, S P;Pfeifer, K
通讯作者：
Pfeifer, K

Individual histone deacetylases in Drosophila modulate transcription of distinct genes.

果蝇中的个体组蛋白脱乙酰酶调节不同基因的转录。