Human DNA transposons: evolutionary history and genomic impact

描述(申请人提供)：这项研究的目的是评估DMA介导的转座子在塑造人类和其他灵长类动物基因组方面的贡献。DMA转座子的移动和积累已被证明在不同的真核生物中引发了广泛的突变，包括总的染色体重排，并被认为是人类基因组不稳定的潜在来源。然而，在任何哺乳动物物种中，DMA转座子的进化历史和扩增动态还没有得到彻底的研究，也不清楚人类基因组中是否存在任何活性转座酶的来源。该项目的第一个目标是深入了解存在于人类基因组中的DMA转座子种群的历史和分布，并评估它们在灵长类基因组进化中的影响。作为实现这一目标的第一步，我们已经确定，目前存在于我们基因组中的~34万个DMA转座子中，至少有~20%是在灵长类动物辐射期间插入的。我们将使用计算工具对灵长类特异的DMA转座子的染色体分布和分子进化进行多物种基因组范围的分析，并通过实验评估它们对灵长类遗传多样性的贡献。这项研究的第二个目的是评估两种转座酶MAR和PGBD3的酶活性，这两种转座酶可能在几个人类组织中表达，并被鉴定为最近在人类基因组中最活跃的转座酶之一。我们将结合比较和进化序列分析来进行体外和体内试验，以测试这些蛋白质(或在本研究过程中确定的其他候选蛋白质)是否保持了它们的催化活性。

DESCRIPTION (provided by applicant): The objective of this research is to assess the contribution of DMA-mediated transposons in shaping the genomes of humans and other primates. The movement and accumulation of DMA transposons have been shown to provoke a wide spectrum of mutations, including gross chromosomal rearrangements, in diverse eukaryotic species and has been regarded as a potential source of instability in the human genome. However, the evolutionary history and amplification dynamics of DMA transposons have not been thoroughly investigated for any mammalian species and it is unknown whether any sources of active transposase resides in the human genome. The first goal of this project is to obtain an in-depth view of the history and distribution of DMA transposon populations residing in the human genome and evaluate their impact in primate genome evolution. As a first step toward this goal, we have determined that at least ~20% of the ~340,000 DMA transposons currently residing in our genome have inserted during the primate radiation. We will perform a multi-species genome- wide analysis of the chromosomal distribution and molecular evolution of primate-specific DMA transposons using computational tools and assess experimentally their contribution to genetic diversity in primates. The second aim of this research is to assess the enzymatic activities of two transposases, MAR and PGBD3, which are potentially expressed in several human tissues and were identified as being among the most recently active in the human genome. We will combine comparative and evolutionary sequence analyses to in vitro and in vivo assays to test whether these proteins (or other candidate identified in the course of this research) have retained their catalytic activities.