Molecular mechanisms of replication stress-induced mitotic chromosome missegregation

Holger Bastians, Göttingen


Structural and numerical chromosome aberrations are commonly and concomitantly detected in cancer and in age-related syndrome cells suggesting a functional relationship between structural and whole chromosome instability (S-CIN and W-CIN, respectively). Recent evidence suggests that replication stress can not only drive S-CIN and the generation of structural chromosome aberrations, but might also be involved in W-CIN leading to whole chromosome missegregation during mitosis resulting in aneuploidy. Preliminary results from our lab support this cross-talk and showed that mild replication stress, which still allows efficient entry into mitosis and long-term cell survival, results in mitotic abnormalities including abnormal mitotic microtubule dynamics and causes whole chromosome aneuploidy.
The objective of this project is to elucidate how replication stress during S-phase causes whole chromosome missegregation during mitosis in human somatic cells. By this, we aim to obtain insights into the relationship between S-CIN and W-CIN induced by replication stress. By using live cell microscopy, we will systematically analyze the progression of mitosis, the execution of chromosome segregation and the formation and resolution of anaphase bridges (in collaboration with Markus Räschle, SP6) in response to increasing levels of experimentally defined replication stress. Based on our preliminary work we will investigate the role of abnormal microtubule dynamics during mitosis as a trigger for whole chromosome missegregation after replication stress. To generalize our findings and to define recurrent mitotic abnormalities induced by replication stress we will evaluate mitotic abnormalities in other model systems exhibiting replication stress. These will include aneuploid cancer cell lines (in collaboration with Matthias Dobbelstein, SP4), fibroblasts from Seckel and Bloom patients (together with Bernd Wollnik, SP5) and aged hematopoietic stem cells (in collaboration with Johanna Flach, SP7). The observed mitotic abnormalities will be associated with the induction of structural and numerical chromosome aberrations that will be comprehensively determined by NGS-based genome analyses in collaboration with our central service project (SP-Z). Finally, in collaboration with Petra Beli (SP1) we will identify and characterize novel regulators of mitosis that are (de)regulated by replication stress and involved in whole chromosome missegregation in response to replication stress.

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