Chromatin Transitions during Early Embryonic Development in Drosophila melanogaster

项目摘要 生物体的遗传物质（DNA）储存在染色体中。了解 正常发育和疾病中的细胞活动需要的不仅仅是DNA序列和个体- 基因组的特殊变异。关键的调节作用也通过将基因组包装成一个 称为染色质的保守核蛋白复合物。染色质的结构及其调控 其代谢机制是独特的重要，因此，在进化中强烈保守。 我们工作的最终目标是了解建立 染色质结构和真核细胞染色体功能的调节。我们将集中在一个 模型胚胎中介导染色质组装和重塑的蛋白质的系统研究 有机体，果蝇（Drosophila melanogaster）。我们将研究组蛋白分子伴侣的活动 和运动因子介导体外染色质组装（在试管中），并研究其特异性 体内（在活的有机体中）的功能作用。 最初，父本DNA作为一种特殊的核蛋白复合物呈递给受精卵。精子 染色质在组成和结构上与正常细胞染色质不同，特别是通过 DNA高度浓缩它是酶促静止的，通过压缩 具有小的碱性、富含半胱氨酸的蛋白质的DNA，称为鱼精蛋白。尽管它对生命周期的重要性 对于任何有性生殖的生物，精子染色质结构的研究很少。为了填补这一空白，我们 将对体外重组的果蝇精子进行生化、生物物理和结构分析 染色质 在受精过程中，卵子面临着将浓缩的精子染色质重塑成一个完整的精子的挑战。 易接近的，有转录和复制能力的形式。我们最近发现了细胞机制， 在体外和体内介导精子染色质重塑。因此，我们也将研究的因素（鱼精蛋白 硫氧还蛋白系统的伴侣蛋白和酶），其介导精子染色质重塑。 该项目的成功完成将导致一个全面的生化和生物 介导各种形式染色质组装的因子的表征。在全球范围内，我们的工作 将提供深入了解染色体组装和维持在细胞调节中的作用 功能，并将适用于理解，诊断和治疗人类疾病， DNA代谢过程中的缺陷。

PROJECT SUMMARY Genetic inheritance material of a living organism (DNA) is stored in chromosomes. Understanding of cellular activities in normal development and disease requires more than the DNA sequence and individual- specific variations of the genome. Critical regulatory roles are also played by packaging of the genome into a conserved nucleoprotein complex termed chromatin. The structure of chromatin and the regulatory machinery of its metabolism are uniquely important and thus, strongly conserved in evolution. The ultimate objective of our work is to understand the relationship between the establishment of chromatin structure and regulation of the function of eukaryotic chromosomes. We will focus on a systematic study of proteins that mediate chromatin assembly and remodeling in the embryo of a model organism, fruit fly (Drosophila melanogaster). We will examine how the activities of histone chaperones and motor factors mediate chromatin assembly in vitro (in a test tube) and investigate their specific functional roles in vivo (in a living organism). Initially, the paternal DNA is presented to a fertilized egg as a specialized nucleoprotein complex. Sperm chromatin differs in composition and structure from the normal cell chromatin, in particular by an extraordinary high degree of DNA condensation. It is enzymatically static and is formed by compaction of DNA with small basic, cysteine-rich proteins termed protamines. Despite its importance for the life cycle of any sexually reproducing organism, sperm chromatin structure has been poorly studied. To fill this gap, we will perform biochemical, biophysical and structural analyses of in vitro reconstituted Drosophila sperm chromatin. At fertilization, the egg faces the challenge of remodeling the condensed sperm chromatin into an accessible, transcription- and replication-competent form. We recently discovered cellular machinery that mediates sperm chromatin remodeling in vitro and in vivo. Thus, we will also study the factors (protamine chaperones and enzymes of the thioredoxin system) that mediate sperm chromatin remodeling. The successful completion of this project will lead to a comprehensive biochemical and biological characterization of factors that mediate the assembly of various forms of chromatin. More globally, our work will provide insights into the role of chromosome assembly and maintenance in regulation of the cell function and will be applicable to understanding, diagnosis and treatment of human diseases that involve defects in processes of DNA metabolism.