Transvection and somatic homolog pairing in Drosophila

描述（由申请人提供）：本申请中提出的实验旨在促进对基因调控和染色体结构的理解。特别是，他们专注于一个奇怪的同源性为基础的过程，称为transvection，其中同源染色体区域的配对导致基因表达的变化。拟议的研究使用果蝇，其中同源染色体在体细胞组织中配对，并且已经证实了几例transvection。然而，它们的范围远远超出果蝇，因为同源染色体区域的配对有助于不同物种中各种有效和必要的调节机制，例如哺乳动物中的X失活和哺乳动物和真菌中未配对DNA/染色质的减数分裂沉默。此外，由于transvection涉及增强子与启动子相互作用的方式，因此本文所述研究的发现将适用于任何生物体中的基因调控。与人类健康的相关性：人类发育对同源性的存在非常敏感，这可以通过同源性驱动的过程如X-失活、亲本印记、等位基因排斥和其他形式的单等位基因现象来证明。这些过程对人类的正常发育至关重要;如果它们出了差错，就会导致严重的异常和疾病。因此，这里提出的研究应该促进对某些形式的疾病的病因学的了解，从而设计改善健康的战略。具体目标：目标1侧重于transvection的形式，涉及增强子的反式作用，探讨反式作用的基本机制，并询问增强子是否可以在顺式连接的启动子和启动子之间翻转。目标2解决配对基因的物理性质，询问配对如何改变基因拓扑结构和染色质结构。最后，目标3提出使用细胞系进行染色质分析和全基因组筛选，以确定参与配对的基因。这些目标使用遗传和分子生物学工具，包括整个生物体遗传学，突变分析，基因置换和转基因技术，RNAi，细胞培养和探测染色质结构的策略。 公共卫生相关性：转染是一个奇特的过程，通过它同源染色体区域的配对导致基因表达的变化。我们的目标是推进transvection以及同源配对的理解，因为这些过程的综合分析将提供独特的见解染色质和染色体结构如何调节基因表达。鉴于基因调控对人类发育和健康的重要性，我们的研究将在医学竞技场中广泛相关。

DESCRIPTION (provided by applicant): The experiments proposed in this application aim to contribute to the understanding of gene regulation and chromosome structure. In particular, they focus on a curious homology-based process, called transvection, in which the pairing of homologous chromosomal regions leads to changes in gene expression. The proposed studies use Drosophila, where homologous chromosomes are paired in somatic tissues and several cases of transvection have been confirmed. However, their reach goes far beyond Drosophila, since pairing of homologous chromosomal regions contributes to a variety of potent and essential regulatory mechanisms in diverse species, such as X-inactivation in mammals and meiotic silencing of unpaired DNA/chromatin in mammals and fungi. Furthermore, as transvection concerns the manner in which enhancers interact with promoters, the findings emerging from the studies described here will pertain to gene regulation in any organism. Relevance to human health: Human development is exquisitely sensitive to the presence of homology, as evidenced by homology-driven processes such as X- inactivation, parental imprinting, allelic exclusion, and other forms of monoallelism. These processes are essential for normal human development; when they go awry, severe abnormalities and disease ensue. As such, the studies proposed here should advance knowledge of the etiology of some forms of diseases and, therefore, the design of strategies to improve health. Specific Aims: Aim 1 focuses on the form of transvection that involves enhancer action in trans, probing the underlying mechanism for trans action and asking whether an enhancer can flip-flop between a cis-linked promoter and promoter in trans. Aim 2 addresses the physical nature of paired genes, asking how pairing can alter gene topology and chromatin structure. Finally, Aim 3 proposes the use of cell lines for chromatin analyses and a whole genome screen to identify genes involved in pairing. These aims use genetic and molecular biological tools, including whole organismal genetics, mutational analyses, gene replacement and transgene technologies, RNAi, cell culture, and strategies for probing chromatin structure. PUBLIC HEALTH RELEVANCE: Transvection is a curious process through which the pairing of homologous chromosomal regions leads to changes in gene expression. Our goal is to advance the understanding of transvection as well as homolog pairing, because a combined analysis of these processes will provide unique insights into how chromatin and chromosome structure regulate gene expression. Given the importance of gene regulation for human development and health, our studies will be broadly relevant in the medical arena.