Human DNA transposons: evolutionary history and genomic impact

描述（由申请人提供）：本研究的目的是评估DMA介导的转座子在塑造人类和其他灵长类动物基因组中的作用。DMA转座子的移动和积累已被证明在不同的真核生物物种中引起广泛的突变，包括总的染色体重排，并且被认为是人类基因组不稳定的潜在来源。然而，对于任何哺乳动物物种，DMA转座子的进化历史和扩增动力学尚未被彻底研究，并且不知道是否有任何活性转座酶的来源存在于人类基因组中。该项目的第一个目标是深入了解人类基因组中DMA转座子群体的历史和分布，并评估其对灵长类基因组进化的影响。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~ 340，000个DMA转座子中至少有~20%在灵长类辐射期间插入。我们将使用计算工具对灵长类特异性DMA转座子的染色体分布和分子进化进行多物种全基因组分析，并通过实验评估它们对灵长类遗传多样性的贡献。本研究的第二个目的是评估两种转座酶MAR和PGBD 3的酶活性，这两种转座酶可能在几种人体组织中表达，并被鉴定为人类基因组中最近活跃的酶。我们将结合联合收割机比较和进化序列分析，在体外和体内测定，以测试这些蛋白质（或其他候选人在本研究过程中确定）是否保留其催化活性。

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.