Department of Neurobiology, Wise Faculty of Life Sciences and Sagol School for Neuroscience, Tel Aviv University, Tel Aviv, Israel 69978.
Curr Biol. 2017 Jul 24;27(14):R720-R730. doi: 10.1016/j.cub.2017.05.043.
Examples of transgenerational inheritance of environmental responses are rapidly accumulating. In Caenorhabditis elegans nematodes, such heritable information transmits across generations in the form of RNA-dependent RNA polymerase-amplified small RNAs. Regulatory small RNAs enable sequence-specific gene regulation, and unlike chromatin modifications, can move between tissues, and escape from immediate germline reprogramming. In this review, we discuss the path that small RNAs take from the soma to the germline, and elaborate on the mechanisms that maintain or erase parental small RNA responses after a specific number of generations. We focus on the intricate interactions between heritable small RNAs and histone modifications, deposited on specific loci. A trace of heritable chromatin marks, in particular trimethylation of histone H3 lysine 9, is deposited on RNAi-targeted loci. However, how these modifications regulate RNAi or small RNA inheritance was until recently unclear. Integrating the very latest literature, we suggest that changes to histone marks may instigate transgenerational gene regulation indirectly, by affecting the biogenesis of heritable small RNAs. Inheritance of small RNAs could spread adaptive ancestral responses.
环境反应的跨代遗传实例正在迅速积累。在秀丽隐杆线虫线虫中，这种可遗传的信息以 RNA 依赖的 RNA 聚合酶扩增的小 RNA 的形式在代际间传递。调节性小 RNA 能够实现序列特异性的基因调控，并且与染色质修饰不同，它们可以在组织间移动，并逃避即时的生殖系重编程。在这篇综述中，我们讨论了小 RNA 从体细胞到生殖系的传递途径，并详细阐述了在特定代数后维持或擦除亲本小 RNA 反应的机制。我们专注于可遗传的小 RNA 和组蛋白修饰之间的复杂相互作用，这些修饰沉积在特定的基因座上。在 RNAi 靶向基因座上，存在着可遗传的染色质标记的痕迹，特别是组蛋白 H3 赖氨酸 9 的三甲基化。然而，这些修饰如何调节 RNAi 或小 RNA 的遗传，直到最近还不清楚。整合最新的文献，我们提出组蛋白修饰的改变可能通过影响可遗传小 RNA 的生物发生，间接地引发跨代基因调控。小 RNA 的遗传可以传播适应性的祖先反应。
