The role of retrotransposons in female reproductive aging

项目摘要 近40%的哺乳动物基因组来自反转录转座子。大多数哺乳动物反转录转座子 在发育和生理上是严格沉默的，但特定逆转座子的诱导可以 在正常卵母细胞和植入前胚胎中观察到。有趣的是，逆转录转座子的一个子集 至少部分地通过充当替代启动子、外显子和 多聚腺苷酸化信号调节近端蛋白编码基因。这种依赖反转录转座子的 基因调控经常改变基因结构和/或基因表达，并已在我们的 卵母细胞生物学和着床前发挥重要发育功能的初步研究 发展。 女性生殖老化提供了一个很好的实验系统来探索其功能重要性 反转录转座子在衰老过程中的作用。与强烈抑制反转录转座子表达的体细胞组织不同， 卵母细胞和植入前胚胎表现出强烈的特异性反转录转座子的诱导，可能 由于在这些独特的发育阶段中广泛的表观遗传重新编程。我们的预赛 研究表明，老化的卵母细胞表现出特定的反转座子的表达变化，以及 RT：基因异构体。有趣的是，IAPEy4家族是逆转座子能力很强的 在老化的卵母细胞中诱导。IAPEy4诱导小鼠DNA损伤及先天免疫应答 老化的卵母细胞，作为其逆转座的结果。此外，MII卵母细胞特异性的MTC-Dicer1亚型 在老化的卵母细胞中被强烈抑制。MTC-Dicer1编码N-末端截短的DICER异构体 这通过RNAi转录后沉默来管理转座子的监视。这些发现 提示老年人逆转录转座子表达改变及逆转座子介导的基因调控 卵母细胞在功能上可以促进生殖衰老。利用基因组学、小鼠遗传学、细胞和 分子生物学，我们建议研究反转录转座子在女性生殖中的重要性 衰老。我们将1)分析青年和青少年中反转录转座子和逆转座子依赖的基因调控。 2)研究异常反转录转座子的重要性 在生殖衰老过程中的诱导和逆转座；3)研究 反转录转座子在生殖衰老中的基因调控。总而言之，拟议的研究 将为控制雌性生殖的细胞和分子机制提供新的见解 衰老，并将为我们理解反转录转座子在发育中的作用增加一个新的维度 和疾病。

Project Summary Nearly 40% mammalian genome originates from retrotransposons. Most mammalian retrotransposons are strictly silenced in development and physiology, yet induction of specific retrotransposons can be observed in normal oocytes and preimplantation embryos. Interestingly, a subset of retrotransposons confer a gene regulatory role, at least in part, by acting as alternative promoters, exons and polyadenylation signals to regulate proximal protein-coding genes. Such retrotransposon-dependent gene regulation frequently alter gene structure and/or gene expression, and have been shown in our preliminary studies to play important developmental functions in oocyte biology and preimplantation development. Female reproductive aging presents an excellent experimental system to probe the functional importance of retrotransposons in aging. Unlike somatic tissues which strongly repress retrotransposon expression, oocytes and preimplantation embryos exhibit a strong induction of specific retrotransposons, possibly due to extensive epigenetic reprogramming during these unique developmental stages. Our preliminary studies show that aged oocytes exhibit expression alteration of specific retrotransposons, as well as RT:gene isoforms. Interestingly, the IAPEy4 family, which is retrotransposition-competent, is strongly induced in aged oocytes. IAPEy4 induction could lead to DNA damage and innate immune response in aged oocytes, as a result of its retrotransposition. In addition, the MII oocyte specific MTC-Dicer1 isoform is strongly repressed in aged oocytes. The MTC-Dicer1 encodes an N-terminally truncated Dicer isoform that governs the transposon surveillance through post-transcriptional silencing by RNAi. These findings suggest that altered retrotransposon expression and retrotransposon mediated gene regulation in aged oocytes could functionally promote reproductive aging. Using genomics, mouse genetics, cell and molecular biology, we proposed to investigate the importance of retrotransposons in female reproductive aging. We will 1) profile retrotransposons and retrotransposon-dependent gene regulation in young and old oocytes and somatic granulosa cells; 2) Investigate the importance of aberrant retrotransposon induction and retrotransposition during reproductive aging; 3) investigate the importance of retrotransposon mediated gene regulation in reproductive aging. Taken together, the proposed studies will provide new insights into the cellular and molecular mechanisms that govern female reproductive aging, and will add a new dimension to our understanding of retrotransposon functions in development and disease.