Cell Cycle Dynamics that ensure Genome Maintenance

点击翻译按钮获取中文摘要

CELL CYCLE CONTROLS THAT ENSURE GENOME MAINTENANCE (COOK) SUMMARY Our research program seeks insight into the fundamental architecture and regulation of the human cell division cycle, with specific focus on DNA replication competence. Complete and efficient duplication of an entire mammalian genome requires that many thousands of DNA replication origins become licensed in G1 phase through the DNA loading of MCM helicase complexes. Loaded MCM complexes render genomic loci competent for replication initiation during S phase. Loss of normal origin licensing control causes genome instability, which can cause oncogenesis, developmental defects, and degeneration. Origin licensing control is as important for ensuring normal genome maintenance as companion mechanisms such as replication fork control and stability or DNA repair, but the regulation of origin licensing is only partly understood. For example, how is complete origin licensing achieved in cells with dramatically different G1 lengths, such as during development or after oncogene activation? How is origin licensing activity distributed in a heterogenous chromatin environment? How is origin licensing controlled during transitions into and out of the cell cycle? These unanswered questions preclude the comprehensive understanding of proliferation control needed to diagnose and treat pathologies in which cell proliferation is a hallmark. Our long-term goal is to understand how DNA replication origin licensing is governed by intracellular and extracellular pathways that control proliferation and development and to understand the outcomes of perturbations to those controls. Our current and future projects are organized into scientific questions clustered into two central goals: Goal 1) Define how MCM loading dynamics regulate G1 progression, Goal 2) Determine the molecular events that establish and maintain cell cycle exit to quiescence. In recent years, we developed innovative experimental tools and approaches using quantitative live cell and fixed single cell analyses in cultured human cells. We combine these tools with molecular genetics and biochemistry. We focus on uncovering molecular mechanisms and their inter-relationships, and then test the consequences of perturbing those mechanisms. Our prior efforts produced a consistent stream of basic scientific discoveries and advances for both the field and the scientific workforce. The impacts of success towards our central goals are to define previously unexplored mechanisms in the mammalian cell cycle and to probe the dynamics of molecular events required for genome maintenance.