The broad objectives of this research are to elucidate the functions of the centrosome in vertebrate somatic cells, and the mechanisms by which it accomplishes these functions. The proposed work is made possible by the successful development of a gamma-tubulin-GFP fusion protein that, for the first time, makes the centrosome clearly visible in living vertebrate somatic cells throughout the cell cycle.
Aim number 1 is to clarify the role the centrosome in spindle formation and maintenance during mitosis in vertebrate somatic cells. To do this I will use laser microsurgery to specifically destroy one or both of the centrosomes at various stages of mitosis, from mid-prophase through anaphase.
Aim number 2 is to determine if cells initiate and complete DNA synthesis, and/or undergo division, after destroying (by laser microsurgery) all or just part of the centrosome during different periods of cell cycle. These experiments will reveal whether the absence of a centrosome, or the presence of a centrosome containing just one centriole in G1 or a single diplosome (i.e., a mother/daughter centriole pair) in G2, inhibits normal progression through the cell cycle in vertebrate somatic cells.
Aim number 3 is to determine the rates with which gamma-tubulin exchanges between the centrosome-associated fraction and the cytoplasmic pool during different periods of cell cycle in untreated cells, and when microtubule dynamics is altered by drugs that affect their stability (e.g., nocodazole, taxol). These experiments will reveal if the centrosome recruits gamma-tubulin only when it is needed (e.g., at the G2/M transition), or if it recruits gamma-tubulin continuously throughout the cell cycle but maintains part of it in an inactive form. This study will also provide additional information on whether the centrosome cycle continues to run in the absence of normal microtubule behavior. Together, the novel data obtained from these studies will allow researchers to better define how the centrosome is involved in cell proliferation and cell cycle control, and may lead to the development of new strategies for the treatment of disease states related to microtubule function (e.g., as cancer, Alzheimer's, arthritis, etc.)
| Sikirzhytski, Vitali; Renda, Fioranna; Tikhonenko, Irina et al. (2018) Microtubules assemble near most kinetochores during early prometaphase in human cells. J Cell Biol 217:2647-2659 |
| Drpic, Danica; Almeida, Ana C; Aguiar, Paulo et al. (2018) Chromosome Segregation Is Biased by Kinetochore Size. Curr Biol 28:1344-1356.e5 |
| Liu, Shiwei; Kwon, Mijung; Mannino, Mark et al. (2018) Nuclear envelope assembly defects link mitotic errors to chromothripsis. Nature 561:551-555 |
| Renda, Fioranna; Pellacani, Claudia; Strunov, Anton et al. (2017) The Drosophila orthologue of the INT6 onco-protein regulates mitotic microtubule growth and kinetochore structure. PLoS Genet 13:e1006784 |
| Magidson, Valentin; He, Jie; Ault, Jeffrey G et al. (2016) Unattached kinetochores rather than intrakinetochore tension arrest mitosis in taxol-treated cells. J Cell Biol 212:307-19 |
| Tikhonenko, Irina; Irizarry, Karen; Khodjakov, Alexey et al. (2016) Organization of microtubule assemblies in Dictyostelium syncytia depends on the microtubule crosslinker, Ase1. Cell Mol Life Sci 73:859-68 |
| Heald, Rebecca; Khodjakov, Alexey (2015) Thirty years of search and capture: The complex simplicity of mitotic spindle assembly. J Cell Biol 211:1103-11 |
| Magidson, Valentin; Paul, Raja; Yang, Nachen et al. (2015) Adaptive changes in the kinetochore architecture facilitate proper spindle assembly. Nat Cell Biol 17:1134-44 |
| Atilgan, Erdinc; Magidson, Valentin; Khodjakov, Alexey et al. (2015) Morphogenesis of the Fission Yeast Cell through Cell Wall Expansion. Curr Biol 25:2150-7 |
| Sikirzhytski, Vitali; Magidson, Valentin; Steinman, Jonathan B et al. (2014) Direct kinetochore-spindle pole connections are not required for chromosome segregation. J Cell Biol 206:231-43 |
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