Linking DNA replication to chromatin organization

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Accurate duplication of the genetic code and its faithful distribution to two daughter cells is critical for the maintenance of genome stability and cell survival. DNA is packaged into compact structures, facilitated by a group of proteins called histones, to build chromatin. Chromatin compaction impacts fundamental processes including DNA replication and gene expression. This project will investigate how the process of DNA replication and chromatin compaction are coordinated during the cell cycle. The outcomes will provide new insights into the role of replication proteins in chromosome segregation and cell cycle progression. The project will also provide opportunities for graduate, undergraduate and high school students to perform research in the fields of cell and molecular biology and genomics, including techniques such as high-resolution microscopy and time-lapse imaging, and computational analyses of large-scale genomics data.Safeguarding the integrity of the genome requires efficient and regulated replication of DNA packaged in chromatin, and important mechanistic questions about this process remain unresolved. In metazoans, pre-replication Complex (preRC) factors, Origin Recognition Complex (ORC, composed of six subunits) and ORC-associated proteins (ORCA/LRWD1) play pivotal roles in maintaining genomic stability and regulate multiple aspects of cell cycle progression. The overall goals of this project are to understand the fundamental molecular mechanisms of DNA replication and chromatin organization by using ORCA/ORC as a tool to probe the coordination of these processes. The specific aims are to determine 1) how chromatin regulates origin licensing and firing and, 2) how preRC proteins regulate chromatin organization at constitutive and facultative heterochromatin. The project utilizes multidisciplinary approaches, including cell and molecular biology, biochemical and biophysical tools to address these fundamental questions. The results are expected to uncover cues that integrate DNA replication with heterochromatin organization and chromosome segregation and elucidate the role of preRC proteins in connecting these processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.