DNA Methylation in Drosophila

果蝇 DNA 甲基化

基本信息

批准号：
7016637
负责人：
KEITH A MAGGERT
金额：
$ 26.48万
依托单位：
TEXAS A&M UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-01-01 至 2010-12-31
项目状态：
已结题

项目摘要

Genomic imprinting is a reversible and differential mark on a set of chromosomes that is determined by the sex of the transmitting parent. This imprint may dramatically affect chromosome behavior or gene expression, and disruption of a proper imprint may result in chromosome loss, cancer, birth defects, or genetic disease. An individual has both maternal and paternal imprints, reflecting that half of its genome has been inherited from each parent. Both sets of imprints are stably maintained throughout the life of an organism. In some cells (e.g., human sperm stem cells), this maintenance may last through thousands of cell divisions over the course of a century. As each chromosome is transmitted to the next generation, all parental imprints are erased in favor of a new set of imprints appropriate to the sex of the transmitting individual. However, since the imprints are maintained, established, and interpreted through unknown mechanisms, it is not known how loss of imprinting leads to disease. Our long-term goal is to understand how sex-specific imprints are established by both males and females, and maintained by the offspring, resulting in parent-of-origin-specific genetic behaviors. Our specific hypothesis is that DNA methylation is an important but transient feature of genomic imprinting. We base this hypothesis on analysis of genomic imprints in fruit flies mutant for the sole known DNA methyltransferase, Mt2. Our preliminary data suggest that DNA methylation is required maternally for establishment of paternal imprints, indicating that the paternal imprint is controlled by the maternal genotype. Based on these observations, we propose to focus our research on imprint establishment by pursuing three specific aims: 1. Identify the DNA sequence that is targeted for methylation by Mt2. We will identify which sequences become methylated by introducing an imprintable transgene, active throughout development and post-mitotic adulthood, and monitoring DNA methylation levels and chromatin structure as they correlate with gene activity. 2. Determine the mode of specificity of Mt2 activity for paternally-derived chromosomes. The key feature of genomic imprinting is the discrimination of paternal from maternal chromosomes, without regard to chromosome sequence. We will focus on testing possible models of chromosome discrimination, including localized gene activity and differences in chromatin structure of maternal and paternal genomes. 3. Identify genetic factors responsible for establishing genomic imprints. We have identified a genetic interval containing a gene required for the establishment of a maternal imprint. We will identify which gene is involved in maternal imprint establishment, and begin to investigate its mode of action.

基因组印迹是一组由传播父的性别决定的一组染色体上的可逆和差异标记。这种烙印可能会极大地影响染色体的行为或基因表达，而适当的烙印的破坏可能会导致染色体丧失，癌症，先天缺陷或遗传疾病。一个人既有母亲和父亲的烙印，反映出其一半的基因组已从每个父母那里继承下来。在生物体的整个生命中，两组烙印都稳定地保持。在某些细胞中（例如人类精子干细胞），在一个世纪的过程中，这种维护可能会持续数千个细胞分裂。由于每个染色体都会传输到下一代，因此所有父母的烙印都将被删除，而有利于一套适合传播个体性别的新烙印。但是，由于这些烙印是通过未知的机制维持，建立和解释的，因此尚不清楚遗传损失是如何导致疾病的。我们的长期目标是了解男性和女性如何确定性别特定的烙印，并由后代维持，导致了父母特定的遗传行为。我们的具体假设是，DNA甲基化是基因组印记的重要但瞬时的特征。我们以对唯一已知DNA甲基转移酶MT2的果蝇突变体中基因组烙印的分析为基础。我们的初步数据表明，建立父亲的烙印所需的DNA甲基化是在母体上需要的，这表明父亲的烙印受母体基因型的控制。基于这些观察结果，我们建议通过追求三个具体目标来将研究重点放在印记建立上：1。确定MT2靶向甲基化的DNA序列。我们将通过引入无形的转基因，在整个发育和有丝分裂后的成年期以及监测与基因活性相关的DNA甲基化水平和染色质结构来确定哪些序列变为甲基化。 2。确定MT2活性的特异性模式。基因组印记的关键特征是对父亲与母体染色体的区分，而无需染色体序列。我们将专注于测试染色体歧视的可能模型，包括局部基因活性以及母体和父亲基因组染色质结构的差异。 3。确定负责建立基因组烙印的遗传因素。我们已经确定了一个遗传间隔，其中包含建立母体烙印所需的基因。我们将确定哪个基因参与孕产妇烙印建立，并开始研究其作用方式。