Centre for Immunobiology, Blizard Institute, Queen Mary University of London, London E1 2AT, UK.
Viruses. 2020 Sep 26;12(10):1089. doi: 10.3390/v12101089.
The human genome has been under selective pressure to evolve in response to emerging pathogens and other environmental challenges. Genome evolution includes the acquisition of new genes or new isoforms of genes and changes to gene expression patterns. One source of genome innovation is from transposable elements (TEs), which carry their own promoters, enhancers and open reading frames and can act as 'controlling elements' for our own genes. TEs include LINE-1 elements, which can retrotranspose intracellularly and endogenous retroviruses (ERVs) that represent remnants of past retroviral germline infections. Although once pathogens, ERVs also represent an enticing source of incoming genetic material that the host can then repurpose. ERVs and other TEs have coevolved with host genes for millions of years, which has allowed them to become embedded within essential gene expression programmes. Intriguingly, these host genes are often subject to the same epigenetic control mechanisms that evolved to combat the TEs that now regulate them. Here, we illustrate the breadth of host gene regulation through TEs by focusing on examples of young (The New), ancient (The Old), and disease-causing (The Ugly) TE integrants.
人类基因组一直在受到选择性压力的影响，以进化来应对新兴病原体和其他环境挑战。基因组进化包括获得新的基因或基因的新同工型，以及基因表达模式的改变。基因组创新的一个来源是转座元件 (TEs)，它们携带自己的启动子、增强子和开放阅读框，可以作为我们自己基因的“调控元件”。TEs 包括可以在细胞内反转录的 LINE-1 元件和代表过去逆转录病毒种系感染残余物的内源性逆转录病毒 (ERVs)。尽管曾经是病原体，但 ERVs 也代表了宿主可以重新利用的外来遗传物质的诱人来源。ERVs 和其他 TEs 与宿主基因已经共同进化了数百万年，这使得它们能够嵌入到重要的基因表达程序中。有趣的是，这些宿主基因经常受到相同的表观遗传调控机制的控制，这些机制是为了对抗现在调控它们的 TEs 而进化的。在这里，我们通过关注年轻 (The New)、古老 (The Old) 和致病 (The Ugly) 的 TE 整合子的例子，说明了 TEs 对宿主基因调控的广泛程度。
