A novel system used by pre-implantation mammalian embryos to amplify environmentally-induced changes in sperm miRNA content after fertilization.

摘要 跨代表观遗传包括将经验的影响传递给后代 通过生殖细胞的表观遗传变化跨越几代人。它在线虫等低等生物中得到了很好的证实。 和植物，越来越多的证据表明，包括人类在内的哺乳动物也存在类似的现象。大有可为 对啮齿动物这一过程的支持来自于对暴露于慢性心理压力下的雄性小鼠的实验 应激，其中特定精子miRNAs水平的应激型特异性变化被认为与 将与压力相关的特征代代相传。然而，精子中miRNAs的含量要低得多。 比大多数细胞，包括早期胚胎中的细胞。这一事实意味着胚胎中必须存在一个系统来 放大并扩大受精后环境中精子含量的变化。事实上，一个自动扩音器 在低等生物中，系统存在并且是跨代表观遗传所必需的。然而，一个 类似的系统在哺乳动物中还没有报道。这笔赠款是由我们最近发现的 似乎是一种新的精子miR-34/449家族的扩增系统。这些mRNAs具有特殊的性质 对此感兴趣，因为我们认为他们与父亲的焦虑和焦虑的传播有关 暴露于慢性社会不稳定的雄性小鼠的雌性后代特有的社交能力缺陷 (CSI)压力。我们发现，CSI应激不仅会降低男性精子中miR-34b/c和miR-449a/b的水平 暴露在CSI应激下的小鼠，以及从它们获得的早期胚胎中，至少在 早期胚胎发育，尽管精子中这些miRNAs的水平比正常水平低得多 存在于植入前的胚胎中。我们发现的扩增系统是基于我们的发现，miR- 34C正常正向调节着床前小鼠自身基因和miR-449基因的表达 这一系统似乎在CSI应激雄性胚胎中受到抑制。令人惊讶的是，我们 在这些胚胎中没有检测到miR-34c的初级转录本或部分加工形式的变化， 提示精子miR-34，可能还有miR-449，调节这类胚胎产生的成员的稳定性 MiRNA家族。这一系统与人类的潜在相关性得到了我们的发现的支持，即：a)miR- 遭受严重虐待和/或功能障碍的男性精子中的34和miR-449水平也会降低 (B)人类胚胎干细胞中似乎存在类似的扩增系统。 这项提议的目标是通过测量miR-34和miR-449的半衰期以及它们的半衰期来检验这一假设。 他们的“拖尾”和“修剪”的程度，这是退化过程的一部分。我们预计这些 这些发现将证明为揭示这些miRNA如何控制自己的实验提供更多的长期资金是合理的 退化，因为这一过程可能是特定形式的跨代表观遗传所必需的 无论是老鼠还是人。

Summary Transgenerational epigenetic inheritance involves transmission of the effects of experiences to offspring across generations via epigenetic changes in germ cells. It is well established in lower organisms like C. elegans and plants, and growing evidence implies a similar phenomenon occurs in mammals including humans. Much support for this process in rodents derives from experiments on male mice exposed to chronic psychological stress, where stress-type specific changes in the levels of specific sperm miRNAs have been implicated in transmitting stress-associated traits across generations. However, sperm contain much lower levels of miRNAs than those of most cells, including those in early embryos. This fact implies a system must exist in embryos to magnify and extend environmental changes in their sperm content after fertilization. In fact, an auto-amplification systems exists and is necessary for transgenerational epigenetic inheritance in lower organisms. However, an analogous system has not been reported in mammals. This grant is driven by our recent discovery of what appears to be a novel amplification system for the sperm miR-34/449 family. These mRNAs are of particular interest in this context because we implicated them in the paternal transmission of enhanced anxiety and defective sociability displayed specifically to female offspring of male mice exposed to Chronic Social Instability (CSI) stress. We found that CSI stress reduces levels of miR-34b/c and miR-449a/b not only in sperm of male mice exposed to CSI stress but also in early embryos derived from them through at least the blastocyst stage of early embryogenesis, even though the levels of these miRNAs in sperm are much lower than that normally present in preimplantation embryos. The amplification system we uncovered is based on our findings that miR- 34c normally positively regulates the expression of its own gene and that for miR-449 in preimplantation mouse embryos, and that this system appears to be suppressed in embryos from CSI stressed males. Surprisingly, we do not detect changes in the primary transcripts or partially processed forms of miR-34c in these embryos, suggesting sperm miR-34, and possibly miR-449, regulates the stability of embryo produced members of this miRNA family. The potential relevance of this system to humans is supported by our findings that; a) both miR- 34 and miR-449 levels are also reduced in sperm of men who experienced severe abusive and/or dysfunctional family life when young; and b) a similar amplification system appears to exist in human embryonic stem cells. The goal of this proposal is to test this hypothesis by measuring the half-lives of miR-34 and miR-449 and their extent of their “tailing” and “trimming”, which are part of the degradation process. We anticipate that these findings will justify more long-term funding for experiments that reveal the how these miRNAs control their own degradation, since this process may necessary for specific forms of transgenerational epigenetic inheritance in both mice and men.