Large-scale chromatin structure and dynamics

描述（由申请人提供）：在高等真核生物染色体中，DNA被折叠成多个层次的组织，产生大约20,000倍的DNA线性压缩。染色质折叠的最高水平，包括30 nm染色质纤维的折叠，占高达500:1的包装比，涉及整个转录和复制功能域的组织，它们在有丝分裂和间期染色单体内的压实，以及它们在间期核内的结构。这种大规模的染色质结构是我们研究的重点。我们的长期目标是确定大规模染色质结构的基本折叠基序，与转录和复制相关的特定构象变化的功能意义，以及调节这些构象转变的潜在机制。我们的具体目标是解决以下问题：1)什么结构基序是间期染色体大规模染色质结构的基础？2)在DNA复制和子染色单体分离过程中，大规模染色质结构发生了哪些结构重排？什么结构基序是有丝分裂染色体凝聚和去凝聚的基础？4)大尺度染色质结构的哪些方面需要凝聚蛋白或内聚蛋白的功能？这项拟议的研究将提供大规模染色质和染色体组织的折叠基序的基本描述。我们未来的工作方向将集中在将大规模染色质组织的结构模型与潜在的生物化学和分子生物学相结合。我们特别感兴趣的是探索大规模染色质结构和核结构与转录，复制和重组之间的机制联系。从这项研究中获得的知识将为基本分子过程的调控提供有价值的见解，并可能有助于指导未来基因治疗载体的设计和稳定的转基因表达。

DESCRIPTION (provided by applicant): Within the higher eukaryotic chromosome, DNA is folded into multiple levels of organization, yielding alinear compaction of DNA of approximately 20,000 fold. The highest levels of chromatin folding, consisting of the folding of 30 nm chromatin fibers, account for up to a 500:1 packing ratio and involve the organization of entire transcription and replication functional domains, their compaction within mitotic and interphase chromatids, and their architecture within interphase nuclei. Poorly characterized, it is this large-scale chromatin structure which is the focus of our research. Our long term objectives are to determine the basic folding motifs underlying large-scale chromatin structure, the functional significance of specific conformational changes associated with transcription and replication, and the underlying mechanisms which regulate these conformational transitions. Our specific aims are to address the following questions: 1) What structural motifs underlie large-scale chromatin structure of interphase chromosomes? 2) What structural rearrangments in large-scale chromatin structure occur during DNA replication and daughter chromatid segregation? 3) What structural motifs underlie mitotic chromosome condensation and decondensation? 4) Which aspects of large-scale chromatin structure require condensin or cohesin function? This proposed research will provide a basic description of the folding motifs underlying large-scale chromatin and chromosome organization. Future directions of our work will focus on integrating structural models of large-scale chromatin organization with the underlying biochemistry and molecular biology. In particular we are interested in exploring the mechanistic links between large-scale chromatin structure and nuclear architecture to transcription, replication and recombination. Knowledge gained from this research should provide valuable insight into regulation of basic molecular processes and may serve to guide design of future gene therapy vectors and stable transgene expression.