Revealing novel molecular mechanisms linking DNA replication and cell fate decisions

ended

All cells in our body share the same genetic information. Cellular identity is determined by epigenetic mechanisms, which control gene expression. Replicating cells should accurately replicate their DNA sequence and copy their epigenetic profile to maintain their identity. DNA replication entails the disruption of the chromatin organization ahead of the replication fork and its restoration behind it. When cells change their identity in either normal development or abnormal processes as cancer, they undergo epigenetic reconfiguration, which defines their new identity. Recent works have revealed a time gap between DNA replication and epigenetic state restoration of many chromatin regulation layers. I hypothesize that the time until chromatin restoration post DNA replication provides a ‘window of opportunity’ for transcription factors and chromatin regulators to bind otherwise inaccessible areas and to facilitate chromatin reconfiguration and that pluripotent cells have specialized chromatin replication proteins, which preserve their high epigenetic plasticity. To test this hypothesis, I will join the lab of Prof. Anja Groth, a leading expert in the mechanisms controlling chromatin replication. Together with my expertise in stem cells and reprogramming, I will address this question with two sequential steps. I will use a cutting edge, quantitative proteomics method in which nascent DNA is affinity purified and its associated proteins are analyzed by mass-spectrometry (NCC-SILAC). I will use this discovery tool to define the proteins dynamically associated with nascent chromatin in pluripotent cells and cells that undergo cell fate transitions. I will then investigate proteins predicted to effect chromatin restoration/reconfiguration to dissect their functional role. This work has the potential to reveal a mechanistic link between DNA replication and cell fate decision and thus significantly contribute to the fields of development, stem cells, and cancer.