Molecular Noise, Transcription Errors and Heritable Phenotypic Change

描述(申请人提供)：这项研究的总体目标是确定在基因调控网络的永久存在和扰动中，从DNA到蛋白质的信息传输错误的起源和后果，这些基因调控网络在大肠杆菌的细胞谱系中产生稳定的表型，例如双稳开关。双稳性被认为是基因回路中的一种决策和记忆机制，依赖于低丰度转录因子之间的正反馈环。这一建议的中心假设是，从DNA到蛋白质的信息传递中的瞬时错误会导致蛋白质波动(分子噪声)，并且当与双稳态调控网络相关时，这些错误可能会导致可遗传的非遗传表型异质性。具体地说，我们认为，由于转录、翻译或蛋白质折叠中的错误而导致功能蛋白(在我们的案例中，是一种负向调节其他基因表达的抑制子)的瞬时消失，可以在生长在相同环境中的遗传相同的细胞中产生可遗传的表型变化。为了从这样的误差中捕捉和量化瞬时事件，将使用两个具有良好特性的双稳系统，乳糖操纵子和波长开关。在这些系统中，从一个表型状态到另一个表型状态的随机切换将是分子噪声的指示器。这项工作将阐明基于蛋白质的表观遗传开关的基本细胞/分子生物学，这可能对生物学和医学的许多基本方面至关重要，包括癌症、衰老、Pron的发生和干细胞的多能性。 与公共健康相关：为了产生多样性，细胞运行由特定蛋白质调节器精心策划的特定程序。有时，这些蛋白质的制造是错误的，导致程序功能障碍，并失去细胞特性。我们的研究旨在了解这些错误在这些蛋白质调节因子上的起源和后果。

DESCRIPTION (provided by applicant): The overall goal of this research is to define the origins and the consequences of errors in information transfer from DNA to protein in the perpetuation and perturbation of genetic regulatory networks that generate stable phenotypes in cellular lineages of Escherichia coli, e.g. bistable switches. Bistability has been proposed as a mechanism for decision-making and memory in gene circuits, relying on positive feedback loops between transcription factors of low abundance. The central hypothesis of this proposal is that transient errors in the information transfer from DNA to protein contribute to protein fluctuation (molecular noise) and that these errors can cause heritable non-genetic phenotypic heterogeneity, when associated with bistable regulatory networks. Specifically, we propose that the transient disappearance of functional protein (in our case, a repressor that negatively regulates the expression of other genes) due to errors in transcription, translation, or protein folding can produce a heritable phenotypic change in genetically identical cells growing in the same environment. To capture and quantify transient events from such errors, two well characterized bistable systems will be used, the lactose operon and the lambda switch. In these systems, the stochastic switching from one phenotypic state to the alternative phenotypic state will be an indicator of molecular noise. This work will illuminate the fundamental cell/molecular biology of protein-based epigenetic switches, which are likely to be critical to many fundamental aspects of biology and medicine including cancer, aging, prion genesis, and pluripotency of stem cells. PUBLIC HEALTH RELEVANCE: To generate diversity, cells run specific programs orchestrated by specific protein regulators. Sometimes the making of these proteins is erroneous, leading to dysfunction of the program, and loss of cellular identity. Our study aims to understand the origin and consequence of these errors on these protein regulators.