Costa Fabrício F
Cancer Biology and Epigenomics Program, Children's Memorial Research Center and Northwestern University's Feinberg School of Medicine, 2300 Children's Plaza, Chicago, IL 60614, USA.
Gene. 2008 Feb 29;410(1):9-17. doi: 10.1016/j.gene.2007.12.008. Epub 2008 Jan 15.
Several aspects of epigenetics are strongly linked to non-coding RNAs, especially small RNAs that can direct the cytosine methylation and histone modifications that are implicated in gene expression regulation in complex organisms. A fundamental characteristic of epigenetics is that the same genome can show alternative phenotypes, which are based in different epigenetic states. Some of the most studied complex epigenetic phenomena including transposon activity and silencing recently exemplified by piRNAs (piwi-interacting RNAs), position effect variegation, X-chromosome inactivation, parental imprinting, and paramutation have direct or indirect participation of an RNA component. Conceivably, most of the non-coding RNAs with no described function yet, are players in epigenetic mechanisms that are still not completely understood. In that regard, RNAs were recently implicated in new mechanisms of genetic information transfer in yeast, plants and mice. In this review article, the hypothesis that non-coding RNAs might be the main component of complex organisms acquired during evolution will be explored. The question of how evolutionary theories have been challenged by these molecules in association with epigenetic mechanisms will also be discussed here.
表观遗传学的几个方面与非编码RNA密切相关，尤其是那些能够指导胞嘧啶甲基化和组蛋白修饰的小RNA，这些修饰与复杂生物体中的基因表达调控有关。表观遗传学的一个基本特征是，相同的基因组可以表现出基于不同表观遗传状态的不同表型。一些研究最多的复杂表观遗传现象，包括最近以piRNA（piwi相互作用RNA）为例的转座子活性和沉默、位置效应斑驳、X染色体失活、亲本印记和副突变，都有RNA成分的直接或间接参与。可以想象，大多数尚未描述功能的非编码RNA都是表观遗传机制中的参与者，而这些机制仍未被完全理解。在这方面，RNA最近被认为参与了酵母、植物和小鼠中遗传信息传递的新机制。在这篇综述文章中，将探讨非编码RNA可能是复杂生物体在进化过程中获得的主要组成部分这一假说。这里还将讨论这些分子与表观遗传机制如何挑战进化理论的问题。
