MOLECULAR GENETICS OF HUMAN X CHROMOSOME INACTIVATION

人类 X 染色体失活的分子遗传学

基本信息

批准号：
2838578
负责人：
Huntington F Willard
金额：
$ 30万
依托单位：
CASE WESTERN RESERVE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1991
资助国家：
美国
起止时间：
1991-01-01 至 2000-11-30
项目状态：
已结题

项目摘要

X chromosome inactivation is the process whereby one of the two X chromosomes in somatic cells of mammalian females is inactivated early in embryogenesis, presumably as a means of dosage compensation between females, with two X chromosomes, and males, with one. While the essential features of X inactivation have been known for over 30 years, the precise molecular, genetic, and developmental details of this lone- range chromosomal control mechanism remain unclear. Over the past few years, substantial progress has been made in the definition and understanding of the various steps involved in X inactivation: initiation early in development through the action of the X inactivation center, promulgation of the inactivation signal and establishment of the inactive state along the chromosome in a strictly cis-limited manner, and maintenance of the various epigenetic states through subsequent cell divisions. A strong candidate for a gene involved in X inactivation, XIST, was described by us in 1991. Since then, significant genetic and developmental evidence has been presented in both humans and mice that supports a role for XIST in the initiation and perhaps establishment of the X inactivation signal. These data provide a framework for further experiments designed to test the hypothesis that the XIST gene, with its regulatory sequences, both controls the initial choice of which X chromosome to inactivate and subsequently establishes a context within the nucleus to distinguish the active from the inactive X chromosome. The experiments described in this application have three specific aims: (1) to determine the nature of the X inactivation center and the role of XIST in initiating X inactivation, by examining the effect(s) of expressing the XIST gene in mouse embryonic stem cells and/or in transgenic mice, by determining the effect(s) of a recently discovered mutation in XIST on the initiation of X inactivation, and by characterizing additional such mutations in families with multiple cases of non-random X inactivation; (2) to determine a developmental context for the establishment of X inactivation, by studying the expression of genes subject to and escaping from X inactivation in mice early in development at the time X inactivation occurs. This is in order to determine whether escape from inactivation is a failure of initiation, establishment, or maintenance of X inactivation; and (3) to examine the chromosomal basis for X inactivation, by studying the distribution of genes on the human and mouse X-chromosomes that are subject to or escape from X inactivation and by using transgenic mice to specifically test the hypothesis that X inactivation is determined at the level of chromosomal domains rather than on an individual gene basis. The proposed experiments should provide a definitive genetic and molecular test of the hypothesis that the XIST gene is, in fact, part of the X inactivation pathway, as well as provide insights into the chromosomal, developmental, and molecular mechanisms by which cis-limited control of X-linked gene expression is achieved.

X染色体失活是两个X染色体之一的过程雌性哺乳动物体细胞中的染色体早期失活在胚胎发生中，大概是作为剂量补偿的一种手段女性有两条X染色体，男性有一条。虽然 X 失活的基本特征已为人所知 30 多年，这个孤独的精确的分子、遗传和发育细节范围染色体控制机制仍不清楚。过去几年多年来，在定义和了解 X 失活涉及的各个步骤：通过 X 失活作用在发育早期启动中心，发布灭活信号并建立沿着染色体以严格顺式限制的方式处于非活性状态，并且通过后续细胞维持各种表观遗传状态部门。参与 X 失活的基因的有力候选者， XIST 是我们在 1991 年描述的。从那时起，显着的遗传和人类和小鼠的发育证据均已提出支持 XIST 在启动和可能建立中的作用 X失活信号。这些数据为进一步旨在检验 XIST 基因及其相关假设的实验调控序列，都控制着 X 的初始选择染色体失活并随后在其中建立上下文细胞核以区分活性 X 染色体和非活性 X 染色体。本申请中描述的实验具有三个具体目标： (1)确定X失活中心的性质及作用 XIST 在启动 X 失活中的作用，通过检查在小鼠胚胎干细胞和/或转基因小鼠，通过确定最近发现的一种或多种效应 X 失活开始时 XIST 发生突变，并且通过描述具有多个病例的家庭中其他此类突变的特征非随机 X 失活； (2)确定发展背景通过研究 X 失活的表达小鼠早期遭受和逃避 X 失活的基因 X失活发生时的发育。这是为了确定逃避失活是否是启动失败， X失活的建立或维持； (3) 检查通过研究 X 失活的染色体基础人类和小鼠 X 染色体上易受或逃避的基因 X 失活并使用转基因小鼠专门测试假设 X 失活是在染色体水平上决定的域而不是单个基因的基础上。拟议的实验应提供明确的遗传和分子测试假设 XIST 基因实际上是 X 失活的一部分途径，并提供对染色体、发育、 X连锁基因顺式限制控制的分子机制表达就达到了。

项目成果

期刊论文数量（47）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Partial X chromosome trisomy with functional disomy of Xp due to failure of X inactivation.

部分 X 染色体三体性，由于 X 失活失败而导致 Xp 功能性二体性。

DOI：
10.1002/ajmg.1320530109
发表时间：
1994
期刊：
American journal of medical genetics
影响因子：
0
作者：
Gustashaw,KM;Zurcher,V;Dickerman,LH;Stallard,R;Willard,HF
通讯作者：
Willard,HF

Pulsed-field map of Xq13 in the region of the human X inactivation center.

人类 X 失活中心区域 Xq13 的脉冲场图。

DOI：
10.1006/geno.1993.1356
发表时间：
1993
期刊：
Genomics
影响因子：
4.4
作者：
Lafreniere,RG;Willard,HF
通讯作者：
Willard,HF

An N-ethyl-N-nitrosourea mutagenesis screen for epigenetic mutations in the mouse.

N-乙基-N-亚硝基脲诱变筛选小鼠表观遗传突变。

DOI：
10.1093/genetics/164.4.1481
发表时间：
2003
期刊：
Genetics
影响因子：
3.3
作者：
Percec,Ivona;Thorvaldsen,JoanneL;Plenge,RobertM;Krapp,ChristopherJ;Nadeau,JosephH;Willard,HuntingtonF;Bartolomei,MarisaS
通讯作者：
Bartolomei,MarisaS

A novel chromatin protein, distantly related to histone H2A, is largely excluded from the inactive X chromosome.

一种与组蛋白 H2A 关系较远的新型染色质蛋白在很大程度上被排除在不活跃的 X 染色体之外。