Stationary phase mutagenesis, a component of cell differentiation

描述(由申请人提供)：我们对经历压力或非复制条件的细胞的突变过程的了解是有限的，也是有争议的。虽然众所周知，应激细胞激活了增加突变的机制，但这些机制如何使突变倾向于形成有益的突变，使细胞能够逃脱应激，目前尚不清楚。全基因组超突变的一个后果是增加了遗传负荷的风险；在这一点上，突变增加使细胞无法存活。解决这一困境的一个有趣的想法，也是这项研究的主题，是压力过大的细胞群体通过分化促进遗传多样性的细胞亚群来降低与高度可变状态相关的风险。这些产生这种突变的机制是保守的，并为进化过程提供了新的观点。这些过程也与病原菌获得抗生素耐药性和绕过免疫反应有关。在分化的动物细胞中，这些过程是有益的，也是有害的。第一，它们产生遗传多样性，第二，它们与肿瘤和退行性疾病的发展有关。这项应用的总体目标是更好地了解一群应激细胞如何激活产生遗传多样性的细胞机制。研究中的假设是，能力的发展(又名。K-状态)与转录和转录修复偶联因子(TRCF-该因子使DNA修复系统偏向高转录区域)相结合，介导了促进枯草杆菌诱变的细胞亚群的形成。我们使用遗传学和基因组学方法来验证这一假设，这些方法检测了发展成K-状态的应激细胞中突变的积累，并将其与非K-细胞进行比较。遗传方法使用实验上控制K-状态的发展和基因标记转录的结构来测量突变。基因组学方法研究K-状态的自然发展和应激过程中的转录反应如何形成基因组突变。最终，这项应用程序研究了一种新的诱变机制，以及它如何重塑基因组并促进进化以应对压力。该项目对人类健康的长期影响是，它研究了治疗退行性和致病性疾病的潜在治疗目标。

DESCRIPTION (provided by applicant): Our knowledge of mutagenic processes in cells experiencing stress or non-replicating conditions is limited and controversial. While it is well established that stressed cells activate mechanisms that increase mutagenesis, it remains unclear how these mechanisms bias mutagenesis towards the formation of beneficial mutations that allow cells to escape stress. One consequence of genome-wide hypermutation is the increased risk of genetic load; the point at which increased mutation render cells non-viable. An interesting idea that addresses this dilemma, and the subject of this research, is that a stressed population of cells reduces the risks associated with hypermutable states by differentiating a subpopulation of cells that promotes genetic diversity. These mechanisms producing this kind of mutations are conserved and inform on novel views on the evolutionary process. These processes are also implicated in the acquisition of antibiotic resistance and bypass of the immune response in pathogenic bacteria. In differentiated animal cells, these processes are both beneficial and detrimental. One, they produce genetic diversity, and two they associate with the development of tumors and degenerative diseases. The overall goal of this application is to gain a better understanding on how a population of stressed cells activates cellular mechanisms that produce genetic diversity. The hypothesis under study is that the development of competence (a.k.a. the K- state) in combination with the process of transcription and the transcription-repair coupling factor (TRCF - this factor biases DNA repair systems towards highly transcribed regions) mediates the formation of a cell subpopulation that promotes mutagenesis in B. subtilis. We test this hypothesis using genetic and genomic approaches that examine the accumulation of mutations in stressed cells that develop into the K-state and compare it to non-K cells. The genetic approach uses constructs that experimentally control the development of the K-state and transcription of a gene marker to measure mutagenesis. The genomic approach examines how natural development of the K-state and transcriptional responses during stress shape genomic mutation. Ultimately, this application examines a novel mutagenic mechanism and how it remodels the genome and promotes evolution in response to stress. The long term human health implications of this project are that it studies potential therapeutic targets for the treatment of degenerative and pathogenic diseases.