Consequences and Control of Randomness in Timing of Intracellular

细胞内时间随机性的后果和控制

• 批准号: 9754192
• 负责人: Abhyudai Singh
• 金额: $ 22.35万
• 依托单位: UNIVERSITY OF DELAWARE
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9754192
• 关键词: Affect; Animals; Automobile Driving; Bacteriophage lambda; Bacteriophages; Biochemical Reaction; Biological Models; Biological Process; Biological Sciences; Buffers; Cardiac Myocytes; Cell Cycle Regulation; Cell Size; Cell membrane; Cell physiology; Cells; Code; Cytolysis; Data; Development; Disease; Ensure; Environment; Escherichia coli; Event; Excision; Exposure to; Feedback; Gene Expression; Gene Expression Regulation; Genetic Transcription; Genome; Growth; H1299; HIV; Human; Individual; Knowledge; Life; Lytic; Malignant Epithelial Cell; Mathematics; Measurement; Measures; Mediating; Medical; Messenger RNA; Modeling; Molecular; Mus; Mutation; Nature; Noise; Non-linear Models; Nucleic Acid Regulatory Sequences; Organism; Pathway interactions; Phenotype; Prokaryotic Cells; Proteins; Regulation; Research; Role; Schedule; Source; Stochastic Processes; Structural Protein; Study models; System; Testing; Time; Translations; Variant; Viral; Virus; age related; cancer cell; chemotherapy; experimental study; gene product; genetic regulatory protein; information processing; insight; life history; lung Carcinoma; mathematical model; mutant; novel; particle; pathogenic bacteria; predictive modeling; protein structure; tat Genes; temporal measurement

Project Summary/Abstract: At the level of individual cells, expression of genes is inherently stochastic across organisms ranging from prokaryotes to human cells. Stochastic expression manifests as cell-to-cell variation in gene product levels even among isogenic cells, and this variation significantly affects biological functions and phenotype. How cells ensure precision in the timing of key intracellular events in the face of of stochastic expression is an intriguing fundamental problem. One simple model for studying event timing is the phage λ's lysis system, where lysis of the infected E. coli cell occurs when a protein, holin, reaches a critical threshold concentration in the cell membrane. Intriguingly, preliminary data reveals precision in timing: individual cells lyse at an optimally scheduled time with minimal statistical fluctuations in timing. The key objective of this proposal is to use λ's lysis system to uncover regulatory mechanisms essential for buffering noise in timing at the single-cell level. Mathematically, noise in the event timing is investigated using the first-passage time framework, where an event is triggered when a stochastic process (holin level) hits a threshold for the first time. Novel analytical calculations of the first-passage time will be performed for stochastic models of gene expression and regulation of varying complexities. Combining theoretical results with single-cell lysis time measurements in both wild-type and mutant phages, the mechanisms controlling stochasticity in the timing of intracellular events will be characterized. In addition, we will use combination of mathematical models and experiments to determine how stochasticity in lysis times drives intercellular variations in the λ progeny count per cell. The first-passage time framework developed here is quite general as timing of diverse cellular processes depends on regulatory molecules reaching critical threshold levels. Identification of regulatory motifs that buffer randomness in the timing of intracellular events has consequences for cell-cycle control and development, where precision is required for proper system functioning. Quantitative characterization of λ's lysis system is also critical for emerging medical applications such as using holin proteins for targeting cancer cells and pathogenic bacteria.

项目摘要/摘要： 在单个细胞的水平上，基因的表达在生物体上固有地是随机的 从原核生物到人类细胞。随机表达表现为细胞到细胞 基因产物水平的变化甚至在同源细胞之间，并且这种变化显着 影响生物学功能和表型。细胞如何确保在钥匙的时间安排中精确 面对随机表达的细胞内事件是一个有趣的基本问题。 研究事件时间安排的一个简单模型是噬菌体λ的裂解系统，其中裂解 当蛋白质Holin达到临界阈值浓度时，被感染的大肠杆菌细胞发生 细胞膜。有趣的是，初步数据揭示了时机的精度：单个细胞在 最佳时间安排的时间，时机的统计波动最小。关键目标的 该建议是使用λ的裂解系统来揭示对法规机制的必需机制 在单细胞级别的定时中缓冲噪声。在数学上，噪音在情况下是 使用第一分行时间框架进行了调查，该框架在该框架中触发事件 随机过程（Holin级别）首次达到阈值。新的分析计算 对于基因表达和调节的随机模型，将执行第一个小时时间 各种复杂性。将理论结果与单细胞裂解时间测量相结合 在野生型和突变噬菌体中，控制随机性的机制 细胞内事件将被表征。此外，我们将使用数学的组合 模型和实验以确定裂解时间中的随机性如何驱动细胞间 每个细胞的λ后代计数的变化。 在这里开发的第一个小时时间框架是大型蜂窝的时间的一般性 过程取决于调节分子达到临界阈值水平。识别 调节基序是在细胞内事件时间内缓冲随机性具有后果 对于细胞周期的控制和开发，正确系统需要精确 功能。 λ的裂解系统的定量表征对于新兴医学也很重要 诸如使用霍林蛋白来靶向癌细胞和致病细菌之类的应用。