Ancient biological functions of present day DNA-damaging enzymes involved in the immune system

当今免疫系统中 DNA 损伤酶的古老生物学功能

• 批准号: RGPIN-2015-04796
• 负责人: Larijani, Mani
• 金额: $ 2.19万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=683348
• 关键词: Ancient; biological; functions; present; day

The goal of this research program is to understand forms and functions of DNA damaging processes in fish. The human immune system uses DNA damage in the form of mutations as well as double strand DNA breaks (DSBs) to initiate the diversification of antigen receptor genes in lymphocytes. Our central hypothesis is that orthologous version of these DNA damaging enzymes in fish are involved in biological roles beyond the immune system, possibly in epigenetic genome reprogramming and development.**** All biological organisms have multiple DNA damage sensing, checkpoint and repair pathways. Consequently cells devote much energy to faithful maintenance and repair of their DNA sequence. In this light, the immune system of jawed vertebrates represents an exception. It is the sole example in all of biology where cells, in the course of their normal development and function, actively mutate and physically reorganize their own genomic DNA in a site-specific manner. The usage of DNA damage by immune systems is thought to have first appeared in cartilaginous fish. **** We have recently discovered that orthologous version of some DNA damaging enzyme involved in the human immune system have distinct activity profiles in specific fish species, and thereby mediate functions that are entirely outside the immune system. Based on this finding, we are proposing a new research program to broadly examine DNA damaging enzymes and their biological functions in the jawless vertebrate sea lamprey, sharks which are cartilaginous fish, and several species of bony fish including Atlantic cod, salmon and coelacanth. Our objectives are to 1) clone and characterize DNA damaging enzymes in these species, 2) examine tissue-specific expression patterns of these enzymes in response to immune stimuli and during development, 3) express, purify and examine the biochemical differences amongst fish DNA damaging enzymes, and 4) compare the biological functions of fish DNA damaging enzymes using genetically modified cells and transgenic animal models.**** If our hypothesis is correct, we expect to find that DNA damaging enzymes in some or all of these fish species have distinct tissue expression patterns and/or different biochemical properties as compared to their mammalian counterparts or each other. Our hypothesis also predicts that these enzymes can prompt different DNA damage responses and carry out divergent biological functions when expressed in cell lines or in transgenic animals. ****This research program represents a new direction for my laboratory and we have initiated local, national and international collaborations with experts in fish biology and immunology. Regardless of whether results support our hypothesis, we will gain a comprehensive understanding of the forms and functions of fish DNA damaging enzymes. Thus, the proposed research will advance knowledge in the fields of fish biology, immune system evolution and DNA damage/repair.**

这项研究计划的目标是了解鱼类DNA损伤过程的形式和功能。人类免疫系统使用突变形式的DNA损伤以及双链DNA断裂（DSB）来启动淋巴细胞中抗原受体基因的多样化。我们的中心假设是，鱼类中这些DNA损伤酶的正向版本参与了免疫系统以外的生物学作用，可能参与了表观遗传基因组重编程和发育。所有生物有机体都具有多种DNA损伤传感、检查点和修复途径。因此，细胞投入大量的能量来忠实地维护和修复它们的DNA序列。在这种情况下，有颌脊椎动物的免疫系统是一个例外。 这是所有生物学中唯一的例子，其中细胞在其正常发育和功能的过程中，以位点特异性的方式主动突变和物理重组其自身的基因组DNA。免疫系统对DNA损伤的利用被认为首先出现在软骨鱼中。* 我们最近发现，参与人类免疫系统的某些DNA损伤酶的正向版本在特定鱼类中具有不同的活性谱，从而介导完全在免疫系统之外的功能。基于这一发现，我们提出了一个新的研究计划，以广泛研究DNA损伤酶及其在无颌脊椎动物海七鳃鳗，鲨鱼是软骨鱼，和几种硬骨鱼，包括大西洋鳕鱼，鲑鱼和腔棘鱼的生物学功能。 我们的目标是1）克隆和表征这些物种中的DNA损伤酶，2）检测这些酶在响应免疫刺激和发育过程中的组织特异性表达模式，3）表达、纯化和检测鱼类DNA损伤酶之间的生化差异，以及4）使用遗传修饰细胞和转基因动物模型比较鱼类DNA损伤酶的生物学功能。如果我们的假设是正确的，我们希望发现，DNA损伤酶在一些或所有这些鱼类物种有不同的组织表达模式和/或不同的生化特性相比，它们的哺乳动物对应物或彼此。 我们的假设还预测，这些酶可以促进不同的DNA损伤反应，并进行不同的生物功能时，在细胞系或转基因动物中表达。* 这项研究计划代表了一个新的方向，我的实验室，我们已经启动了地方，国家和国际合作的专家在鱼类生物学和免疫学。无论结果是否支持我们的假设，我们将获得一个全面的了解鱼类DNA损伤酶的形式和功能。因此，拟议的研究将推进鱼类生物学，免疫系统进化和DNA损伤/修复领域的知识。