Genomic Instability

工作总结：基因组的不稳定性有几个来源。这些问题包括DNA修复、转录和复制方面的问题。它们还包括由许多DNA代谢酶控制的DNA拓扑新陈代谢的缺陷。其中一组是拓扑异构酶，我们一直对它们的功能感兴趣，因为它与DNA损伤的处理有关。最近的一些研究表明，人类拓扑异构酶I(HtopoI)可以识别各种DNA损伤，从而形成对细胞有害的共价拓扑异构酶I-DNA复合体。我们已经研究了htopoI是否识别另一个共价捕获在DNA底物上的htopoI。为此，我们创建了一种含有特定拓扑异构酶I结合序列的人造DNA底物，其中该酶以共价结合的形式被捕获。我们证明，在体外，游离的htopoI刺激在共价结合的拓扑异构酶I上游立即形成一个额外的切割复合体。我们还研究了群体水平的基因组不稳定性以及这种不稳定性如何随年龄的变化。这是在参加巴尔的摩老龄化纵向研究的人类的DNA中完成的。在这里，我们测量DNA修复基因的一些多态，以确定是否存在随着年龄增长或与年龄相关的疾病的显着变化。特别是，我们重点研究了人类早衰障碍--沃纳综合征的基因多态性。到目前为止，我们还没有观察到特定的多态与年龄相关疾病之间的任何联系，但只检查了几个多态，我们计划研究更多

Summary of work: Genomic instability arises from several sources. These include problems with DNA repair, transcription and replication. They also include deficiencies in the topological metabolism of DNA, which is controlled by a number of DNA metabolic enzymes. A group of these are topoisomerases, and we have been interested in their function as it relates to the handling of DNA damage. Several recent studies have shown that human topoisomerase I (htopoI) can recognize various DNA lesions and thereby form a covalent topoisomerase I-DNA complex, which is known to be detrimental to cells. We have investigated whether htopoI recognizes another htopoI that is covalently trapped on a DNA substrate. For this purpose we created an artificial DNA substrate containing a specific topoisomerase I binding sequence, where the enzyme was trapped in the covalently bound form. We demonstrate that, in vitro, free htopoI stimulates the formation of an additional cleavage complex immediately upstream of the covalently bound topoisomerase I. We also study genomic instability at the population level and how this changes with aging. This is done in DNA from humans enrolled in the Baltimore Longitudinal Study on Aging. Here we measure a number of polymorphisms in DNA repair genes to determine if there are significant changes with aging or with age-associated diseases. In particular, we have focused on polymorphisms in the gene for the human premature aging disorder, Werner syndrome. So far we have not observed any connections between specific polymorphisms and age associated diseases but only a few polymorphisms have been examined, and we plan to look at many more