Accurate chromosome segregation is essential for the propagation of species and the viability of cells, and is driven by a complex microtubule-based structure called the spindle. Intensive biochemical, genetic, and proteomic efforts provide an extensive catalogue of proteins that participate in spindle organization and spindle-dependent chromosome movement. However, these efforts don't reveal the molecular mechanisms that ensure faithful chromosome segregation in mammalian cells. Recently, we showed that the most common cause of chromosome mis-segregation in human tumor cells is the persistence of kinetochore-microtubule (K- MT) attachment errors. However, our understanding for how K-MT attachments are regulated to promote error correction remains starkly incomplete. We don't understand how different molecular components create a coherent output to fine-tune K-MT attachment stability during cell cycle transitions. We also don't understand how aneuploidy influences genome stability and cell survival. It is our goal in the forthcoming funding period to combine biochemical methods and live cell imaging to test models and determine the mechanisms of the regulation of K-MT attachments in mitosis. Understanding these mechanisms could lead to new therapeutic approaches for cancer treatment.
The specific aims of this proposal are, 1.) To use live cell imaging to determine the biochemical changes underlying the transition from prometaphase to metaphase;2.) To combine live cell imaging with molecular tools to test the model that changes in the copy number of single genes is sufficient to undermine faithful chromosome segregation by disrupting K-MT attachment dynamics;3.) To quantify the genetic damage caused by persistent K-MT attachment errors;and 4.) To test mechanisms that suppress aneuploid cell growth in live animals.

Public Health Relevance

Errors in chromosome segregation cause aneuploidy that causes birth defects and is commonly associated with advanced stage cancer. The goal of the experiments proposed here is to combine biochemical methods and live cell imaging to identify the proteins and determine the mechanisms responsible for high fidelity chromosome segregation in human cells. Data generated from this work will provide insight into mechanisms of aneuploidy in tumor cells and may reveal strategies for therapy of chromosomally unstable aneuploid tumors.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Method to Extend Research in Time (MERIT) Award (R37)
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Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
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Deatherage, James F
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Dartmouth College
Schools of Medicine
United States
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Kleyman, Marianna; Kabeche, Lilian; Compton, Duane A (2014) STAG2 promotes error correction in mitosis by regulating kinetochore-microtubule attachments. J Cell Sci 127:4225-33
Bakhoum, Samuel F; Silkworth, William T; Nardi, Isaac K et al. (2014) The mitotic origin of chromosomal instability. Curr Biol 24:R148-9
Bakhoum, Samuel F; Kabeche, Lilian; Murnane, John P et al. (2014) DNA-damage response during mitosis induces whole-chromosome missegregation. Cancer Discov 4:1281-9
Kabeche, Lilian; Compton, Duane A (2013) Cyclin A regulates kinetochore microtubules to promote faithful chromosome segregation. Nature 502:110-3