SP-1: Deciphering signaling pathways that promote accurate chromosome segregation after replication stress

Petra Beli, Mainz

Summary

To maintain genome stability, human cells depend on accurate DNA replication in S-phase and chromosome segregation in mitosis. Replication stress refers to slowing down or stalling of replication forks that occurs due to DNA lesions, R-loops or oncogene activation. One consequence of replication stress is entry of cells into mitosis with incompletely replicated DNA and thus aberrant mitosis. Phosphorylation of proteins by kinase ATR and its downstream effector CHK1 protects stalled replication forks and activates the G2/M checkpoint. In response to mild replication stress cells might fail to activate the checkpoint and enter mitosis with incompletely replicated DNA. Although the replication stress response in interphase is relatively well studied, the signaling pathways and molecular mechanisms acting in mitosis to promote faithful chromosome segregation after replication stress remain poorly understood. In this collaborative project, we will employ quantitative mass spectrometry (MS)-based proteomics to analyze phosphorylation- and ubiquitin-dependent signaling that is induced in mitotic cells after replication stress. Furthermore, we will investigate the patterns of protein recruitment to and removal from mitotic chromatin. Functional assays aimed to analyze genomic instability and mitotic dysfunction will be performed to characterize the role of identified proteins and posttranslational modifications in mitosis after replication stress.

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