Grant: Project Grant

The broad goal of the research proposed here is to improve our understanding of how DNA, the hereditary information that determines the development and functioning of all living organisms, is maintained over a human lifetime. Specifically, I propose to focus on the replication of DNA that is enriched for guanine, one of the four DNA bases, in normal development and genome instability. The proposed research is a logical extension of earlier, published work from my laboratory. Following studies on the purification and self-renewal of blood forming stem cells, we focused on the role of telomeres, the normal ends of chromosomes, in normal and malignant cell proliferation. This work led us to studies of the pathways that ensure proper replication of the guanine (G)-rich DNA. In the course of this work, we discovered several genes including DOG-1 (FANCJ) and RTEL that are required for replication of G-rich DNA. Interestingly, both these genes encode for proteins with helicase activity: that is they are capable of unwinding secondary DNA structures of G-rich DNA, called guanine quadruplex (G4) structures. Recently we found that the Bloom helicase protein, deficient in patients with the cancer-prone Bloom syndrome, is required to suppress recombination at G-rich DNA. Here we propose further studies on the pathways required to resolve G4 structures and faithfully replicate Grich DNA at telomeres and at genes. The goal of these studies is to better understand the nature of the lesions that cause problems during replication of G-rich DNA and the pathways that different cells have available to solve such problems. Our studies will generate new knowledge about DNA replication and DNA repair and pathways that prevent genome instability. A better understanding of these pathways has broad potential for our understanding of normal development and aging as well specific disorders linked to DNA repair defects including specific types of cancer.