Sharma Abhay
Biomol Concepts. 2015 Apr;6(2):87-103. doi: 10.1515/bmc-2015-0005.
Transgenerational epigenetic inheritance in animals has increasingly been reported in recent years. Controversies, however, surround this unconventional mode of heredity, especially in mammals, for several reasons. First, its existence itself has been questioned due to perceived insufficiency of available evidence. Second, it potentially implies transfer of hereditary information from soma to germline, against the established principle in biology. Third, it inherently requires survival of epigenetic memory across reprogramming, posing another fundamental challenge in biology. Fourth, evolutionary significance of epigenetic inheritance has also been under debate. This article pointwise addresses all these concerns on the basis of recent empirical, theoretical and conceptual advances. 1) Described here in detail are the key experimental findings demonstrating the occurrence of germline epigenetic inheritance in mammals. 2) Newly emerging evidence supporting soma to germline communication in transgenerational inheritance in mammals, and a role of exosome and extracellular microRNA in this transmission, is thoroughly discussed. 3) The plausibility of epigenetic information propagation across reprogramming is highlighted. 4) Analyses supporting evolutionary significance of epigenetic inheritance are briefly mentioned. Finally, an integrative model of 'evolutionary transgenerational systems biology' is proposed to provide a framework to guide future advancements in epigenetic inheritance.
近年来，动物中的跨代表观遗传继承现象越来越多地被报道。然而，由于多种原因，这种非传统的遗传模式存在争议，尤其是在哺乳动物中。首先，由于现有证据被认为不足，其存在本身受到质疑。其次，它可能意味着遗传信息从体细胞转移到生殖细胞，这与生物学中既定的原则相悖。第三，它本质上要求表观遗传记忆在重编程过程中得以保留，这在生物学中构成了另一个根本性挑战。第四，表观遗传继承的进化意义也一直存在争议。本文基于近期的实证、理论和概念进展，逐一探讨了所有这些问题。1）详细描述了证明哺乳动物中生殖系表观遗传继承发生的关键实验结果。2）深入讨论了支持哺乳动物跨代遗传中体细胞与生殖细胞通讯以及外泌体和细胞外微小RNA在这种传递中的作用的新出现证据。3）强调了表观遗传信息在重编程过程中传播的合理性。4）简要提及了支持表观遗传继承进化意义的分析。最后，提出了一个“进化跨代系统生物学”的综合模型，以提供一个框架来指导表观遗传继承领域未来的进展。
