Functional characterization of the Harbi1 and Naif1 transposon-derived genes in vertebrates

脊椎动物 Harbi1 和 Naif1 转座子衍生基因的功能表征

• 批准号: 282568825
• 负责人: Professor Dr. Zoltan Ivics
• 金额: --
• 依托单位: Abteilung Medizinische Biotechnologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/282568825?language=en
• 关键词: Functional; characterization; Harbi1; Naif1; transposon

Spatio-temporal coordination of eukaryotic gene expression relies on transcriptional and post-transcriptional regulatory networks. Although some of the components and function of these networks have been elucidated, the mechanisms by which such intricate circuits originate and evolve remain poorly understood. Significant fractions of eukaryotic genomes are composed of transposable elements (TEs) that are able to move and replicate in the genome. TEs are best viewed as genomic parasites with no apparent adaptive value to the host cell in which they reside. Thus, in the absence of selective pressure to maintain mobility, the vast majority of TEs has become transpositionally inactivated over evolutionary time, and has been viewed as "junk DNA" without any apparent cellular function. However, it is being increasingly realized that the spread of TEs in the genome likely played a key role in the evolution of novel gene functions. For example, through an evolutionary process termed "domestication" TE-derived transposase proteins have been recurrently recruited into cellular pathways as regulatory elements. Harbi1 and Naif1 are highly conserved genes in vertebrates that have been derived from an ancient PIF/Harbinger transposon in a common ancestor of jawed vertebrates some 500 million years ago. Conservation of these genes implies that they have been under selection for important cellular functions, and their phylogenetic relationship suggests that both are involved in the same molecular pathway. Naif1 has been implicated in apoptotic functions. Our preliminary data suggest that Naif1 is a DNA-binding protein that promotes nuclear import of Harbi1, where it may recruit Harbi1 to genomic sites through protein-protein interactions. Sequence conservation of the catalytic domain of Harbi1 suggests that it might have retained nuclease activity. However, the role(s) of these two genes in cellular homeostasis and organismal development have been enigmatic. In this project we leverage biochemical assays in vitro, genome-wide ChIP and transcriptional profiling in cultured cells ex vivo, and phenotyping of knockout (KO) animals in the zebrafish model in vivo to understand and functionally annotate these genes and the genetic networks they regulate. The project will greatly contribute to our understanding of the mechanisms and roles of TEs as an important force in the creation of genetic novelty.

真核生物基因表达的时空协调依赖于转录和转录后调控网络。虽然这些网络的一些组成部分和功能已经阐明，但这种复杂电路起源和演变的机制仍然知之甚少。真核生物基因组的重要部分由能够在基因组中移动和复制的转座因子（TE）组成。TE最好被视为基因组寄生虫，对它们所驻留的宿主细胞没有明显的适应价值。因此，在缺乏保持流动性的选择压力的情况下，绝大多数TE在进化过程中已经变得转座失活，并且被视为没有任何明显细胞功能的“垃圾DNA”。然而，人们越来越认识到，基因组中TE的传播可能在新基因功能的进化中发挥了关键作用。例如，通过称为“驯化”的进化过程，TE衍生的转座酶蛋白作为调节元件被反复募集到细胞途径中。Harbi 1和Naif 1是脊椎动物中高度保守的基因，它们来源于大约5亿年前有颌脊椎动物共同祖先中的古老PIF/Harbinger转座子。这些基因的保守性意味着它们在重要的细胞功能中受到选择，它们的系统发育关系表明两者都参与了相同的分子途径。Naif 1与凋亡功能有关。我们的初步数据表明，Naif 1是一种DNA结合蛋白，促进Harbi 1的核输入，在那里它可以通过蛋白质-蛋白质相互作用将Harbi 1招募到基因组位点。Harbi 1催化结构域的序列保守性表明它可能保留了核酸酶活性。然而，这两个基因在细胞内稳态和生物体发育中的作用一直是谜。在这个项目中，我们利用体外生化检测，全基因组ChIP和体外培养细胞的转录谱，以及斑马鱼模型中敲除（KO）动物的表型分析，以了解和功能注释这些基因及其调控的遗传网络。该项目将极大地有助于我们理解的机制和作用的TE作为一个重要的力量，在创造遗传新奇。