Title: Mitotic spindle stability and chromosome missegregation in cancer
Funder: Cancer Research UK

Abstract: Background Understanding how cells divide is a major goal in cancer research. First, halting tumour cell division in cancer is a valid therapeutic route, and so finding innovative ways to target cell division – while minimising side effects to patients – relies on a full understanding of the cell division machinery. Second, errors in cell division cause aneuploidy, a form of genomic instability thought to drive tumour formation and propagation. Therefore, understanding the causes of chromosome missegregation during cell division is important to prevent cancer initiation. During cell division, chromosomes are shared with high fidelity to the two daughter cells by the mitotic spindle. We have identified and partially characterized a “mesh” of proteins that stabilise the microtubules of the mitotic spindle. One major component is the TACC3–clathrin–ch-TOG complex, and we have found additional candidate protein components. Understanding how these proteins bind to one another and to microtubules will allow us to develop strategies to prevent these complexes from stabilising the spindle. This opens the door to new treatments that target mitotic cells specifically, reducing the side effects associated with broadbase microtubule inhibitors. Although mitosis is a high fidelity process, sometimes mistakes do occur and chromosomes become missegregated, leading to aneuploidy. We have exciting preliminary evidence that endomembranes play an active role in the missegregation of chromosomes. The mechanistic details of these events will be explored in this programme. Aims 1. Structural characterisation of TACC3–clathrin–ch-TOG complex on microtubules 2. Localisation and characterisation of other microtubule mesh proteins 3. Role of endomembranes in chromosome missegregation Methods We mainly use imaging of dividing human cells using spinning disk confocal microscopy and electron microscopy. Cells are genetically engineered using CRISPR/Cas9 to allow us to track mesh proteins by light and electron microscopy. We will also use cryoelectron microscopy and other biophysical methods to visualise the structure of mesh proteins at high resolution. We will combine structural information with cell biological information using electron tomography of dividing mitotic cells. How the results of this research will be used This is a fundamental science programme to understand cell biology phenomena at the molecular scale. Nevertheless, there is a line-of-sight towards possible therapies that might arise from this work. Breaking apart the protein complexes that stabilise the mitotic spindle has the potential to halt cell division in cancer with fewer side effects than existing compounds, i.e. microtubule poisons that interfere with microtubule function in healthy cells.

Lay abstract: Background Understanding how cells divide is a major goal in cancer research. First, halting tumour cell division in cancer is a valid therapeutic route, and so finding innovative ways to target cell division – while minimising side effects to patients – relies on a full understanding of the cell division machinery. Second, errors in cell division cause aneuploidy, a form of genomic instability thought to drive tumour formation and propagation. Therefore, understanding the causes of chromosome missegregation during cell division is important to prevent cancer initiation. During cell division, chromosomes are shared with high fidelity to the two daughter cells by the mitotic spindle. We have identified and partially characterized a “mesh” of proteins that stabilise the microtubules of the mitotic spindle. One major component is the TACC3–clathrin–ch-TOG complex, and we have found additional candidate protein components. Understanding how these proteins bind to one another and to microtubules will allow us to develop strategies to prevent these complexes from stabilising the spindle. This opens the door to new treatments that target mitotic cells specifically, reducing the side effects associated with broadbase microtubule inhibitors. Although mitosis is a high fidelity process, sometimes mistakes do occur and chromosomes become missegregated, leading to aneuploidy. We have exciting preliminary evidence that endomembranes play an active role in the missegregation of chromosomes. The mechanistic details of these events will be explored in this programme. Aims 1. Structural characterisation of TACC3–clathrin–ch-TOG complex on microtubules 2. Localisation and characterisation of other microtubule mesh proteins 3. Role of endomembranes in chromosome missegregation Methods We mainly use imaging of dividing human cells using spinning disk confocal microscopy and electron microscopy. Cells are genetically engineered using CRISPR/Cas9 to allow us to track mesh proteins by light and electron microscopy. We will also use cryoelectron microscopy and other biophysical methods to visualise the structure of mesh proteins at high resolution. We will combine structural information with cell biological information using electron tomography of dividing mitotic cells. How the results of this research will be used This is a fundamental science programme to understand cell biology phenomena at the molecular scale. Nevertheless, there is a line-of-sight towards possible therapies that might arise from this work. Breaking apart the protein complexes that stabilise the mitotic spindle has the potential to halt cell division in cancer with fewer side effects than existing compounds, i.e. microtubule poisons that interfere with microtubule function in healthy cells.

Research activity codes: 1.1 NORMAL BIOLOGICAL DEVELOPMENT AND FUNCTIONING;2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: CANCER AND NEOPLASMS;GENERIC HEALTH RELEVANCE