Mechanisms for Measuring the Nucleocytoplasmic Ratio in Early Embryogenesis

早期胚胎发生中核质比率的测量机制

• 批准号: 8451061
• 负责人: Shelby Alexander Blythe
• 金额: $ 5.39万
• 依托单位: PRINCETON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8451061
• 关键词: Accounting; Architecture; Arginine; Biological; Biological Assay; Biological Process; Cell Growth Processes; Cell Nucleus; Cell Proliferation; Cell Size; Cell division; Cells; Chromatin; Complex; Coupled; Coupling; DNA; Data; Defect; Development; Diploidy; Dose; Drosophila genus; Drosophila melanogaster; Embryo; Embryonic Development; Ensure; Event; Fertilization; Fibrinogen; Gene Activation; Gene Expression; Genetic; Genetic Transcription; Genetic Translation; Genome; Genomics; Global Change; Goals; Hand; Histones; Homeostasis; Hour; Investigation; Logic; Maternal Messenger RNA; Measurement; Measures; Methylation; Modeling; Modification; Molecular; Monitor; Phenotype; Process; Property; Regulation; Regulation of Cell Size; Research; Research Project Grants; Role; System; Testing; Time; Tissues; Translations; Work; biological systems; cell growth; chromatin modification; genome-wide; loss of function; mRNA Expression; mutant; prevent; stem

DESCRIPTION (provided by applicant): One fundamental property of biological systems is the coordination of cellular proliferation with the regulation of cell size. This coordination ensures that cells grow to a minimum size prior to dividing and functions as a checkpoint to prevent unrestricted proliferation. While it is not fully understood how cells measure their size, it has lng been appreciated that the determination of cell size is coupled to the ratio of genomic DNA to cytoplasmic volume. This indicates that there exists a biological mechanism for measuring this nucleo-cytoplasmic (N:C) ratio, but the components of this mechanism are currently unknown. This research project proposes to use the study of the maternal to zygotic transition of the fruit fly Drosophila melanogaster as a model to understand further the mechanism of N:C ratio measurement. Early embryos couple the transition from maternal to zygotic control of development to the measurement of the N:C ratio. This transition results in global changes in embryonic gene expression, stemming, in part, from coordinated activities of both translation-regulatory and chromatin modifying mechanisms. However, a precise account of the mechanism underlying this coordination has been hampered by a paucity of mutants that specifically disrupt this process. The proposed investigation will examine the function of two recently identified Drosophila mutants with potential defects in N:C ratio measurement (dfmr1/capr and valois), and use these factors as a molecular entry point to test two models for quantifying the N:C ratio. I propose to investigate the mechanisms regulating the measurement of the N:C ratio in early Drosophila embryos by exploring the cause of the mutant phenotypes of valois and dfmr1/capr. Since valois and dfmr1 have been shown to interact with additional factors, I propose to test whether loss of function for these partners uncovers additional mutants with putative defects in N:C ratio measurement. With these mutants in hand, I will measure the effect of these defects on the temporal control of zygotic gene activation, using an assay developed in the Wieschaus lab that distinguishes N:C ratio-dependent and -independent effects. Finally, I will test whether mutants of this class interact physically and genetically in order to understand further the regulatory logic underlying this phenotypic class of mutants. I propose two models for quantification of the N:C ratio by translation- or chromatin-coupled mechanisms. By further investigation of dfmr1/capr-dependent translational control of maternal mRNA expression, and valois-dependent chromatin modification, I will examine two candidate mechanisms for measuring the N:C ratio. This project will therefore expand the understanding both of early developmental regulatory systems, and of a fundamental mechanism for measuring cellular size.

描述（由申请人提供）：生物系统的一个基本特性是细胞增殖与细胞大小调节的协调。这种协调确保细胞在分裂之前生长到最小尺寸，并作为检查点防止无限制的增殖。虽然尚不完全理解细胞如何测量它们的大小，但已经认识到细胞大小的确定与基因组DNA与细胞质体积的比率相关联。这表明存在测量这种核质（N：C）比的生物学机制，但该机制的组成部分目前尚不清楚。本研究计划拟以果蝇（Drosophila melanogaster）的母体到合子转变为模型，进一步了解N：C比率测量的机制。早期胚胎将从母体到合子控制发育的过渡与N：C比率的测量结合起来。这种转变导致胚胎基因表达的全球性变化，部分源于免疫调节和染色质修饰机制的协调活动。然而，这种协调机制的精确描述受到缺乏突变体的阻碍，这些突变体专门破坏这一过程。拟议的调查将检查两个最近确定的果蝇突变体的功能与潜在的缺陷，在N：C比测量（dfmr 1/capr和valois），并使用这些因素作为一个分子的切入点，以测试两个模型定量的N：C比。我建议通过探索valois和dfmr 1/capr突变表型的原因来研究调节早期果蝇胚胎中N：C比率测量的机制。由于valois和dfmr 1已被证明与其他因素的相互作用，我建议测试这些合作伙伴的功能丧失是否会发现额外的突变体与推定的缺陷，在N：C比测量。有了这些突变体，我将测量这些缺陷对合子基因激活的时间控制的影响，使用Wieschaus实验室开发的一种测定法，该测定法区分N：C比率依赖和独立的影响。最后，我将测试这类突变体是否在物理和遗传上相互作用，以进一步了解这类表型突变体的调控逻辑。我提出了两个模型的量化的N：C比的翻译或染色质耦合机制。通过进一步研究母体mRNA表达的dfmr 1/capr依赖性翻译控制和valois依赖性染色质修饰，我将研究两种用于测量N：C比率的候选机制。因此，该项目将扩大对早期发育调节系统和测量细胞大小的基本机制的理解。