Silencing of Transposable Elements by piRNAs in Drosophila: An Evolutionary Perspective.
Silencing of Transposable Elements by piRNAs in Drosophila: An Evolutionary Perspective.
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果蝇中 piRNA 沉默转座元件：进化视角
DOI：
10.1016/j.gpb.2017.01.006
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发表时间：
2017-06
期刊：
影响因子：
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通讯作者：
Lu J
中科院分区：
文献类型：
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作者：
Luo S;Lu J
转座因子（Transposable elements，TE）是一种可以在基因组中移动的DNA序列。TE通过多种机制极大地塑造了宿主生物的基因组、转录组和蛋白质组。然而，TE通常会破坏基因并使宿主基因组不稳定，这大大降低了宿主生物体的适应性。了解TE的基因组分布和进化动力学将大大加深我们对TE介导的生物过程的理解。大多数TE插入在果蝇中具有高度多态性，这为我们在种群水平上研究TE的进化提供了一个很好的系统。几十年的理论和实验研究已经建立了“转座-选择”群体遗传学模型，该模型假设TE复制和纯化选择之间的平衡决定了基因组中TE的拷贝数。在过去的十年中，P元件诱导的懦弱睾丸（PIWI）相互作用RNA（piRNA）被证明是果蝇TE活动的主要抑制子。piRNA的发现彻底改变了我们对TE抑制的理解，因为它揭示了宿主生物体已经进化出一种适应性机制来防御TE入侵。在理解piRNA抑制活性TE的分子机制方面已经取得了巨大进展，尽管该过程中的许多细节仍有待进一步探索。piRNA和TE之间的相互作用很好地解释了果蝇中I-R和P-M系统的杂交发育不全的分子机制，这几十年来一直困扰着进化生物学家。皮尔纳抑制途径为我们提供了一个无与伦比的系统来研究寄生虫和宿主生物之间的共同进化过程。
Transposable elements (TEs) are DNA sequences that can move within the genome. TEs have greatly shaped the genomes, transcriptomes, and proteomes of the host organisms through a variety of mechanisms. However, TEs generally disrupt genes and destabilize the host genomes, which substantially reduce fitness of the host organisms. Understanding the genomic distribution and evolutionary dynamics of TEs will greatly deepen our understanding of the TE-mediated biological processes. Most TE insertions are highly polymorphic in Drosophila melanogaster, providing us a good system to investigate the evolution of TEs at the population level. Decades of theoretical and experimental studies have well established “transposition-selection” population genetics model, which assumes that the equilibrium between TE replication and purifying selection determines the copy number of TEs in the genome. In the last decade, P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs) were demonstrated to be master repressors of TE activities in Drosophila. The discovery of piRNAs revolutionized our understanding of TE repression, because it reveals that the host organisms have evolved an adaptive mechanism to defend against TE invasion. Tremendous progress has been made to understand the molecular mechanisms by which piRNAs repress active TEs, although many details in this process remain to be further explored. The interaction between piRNAs and TEs well explains the molecular mechanisms underlying hybrid dysgenesis for the I-R and P-M systems in Drosophila, which have puzzled evolutionary biologists for decades. The piRNA repression pathway provides us an unparalleled system to study the co-evolutionary process between parasites and host organisms.