Microtubule dynamics and error correction

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Modified Project Summary/Abstract Section The broad goal of this project is to understand how force generation by kinesin-related motors and dynamic microtubules controls the fidelity of chromosome segregation. Both microtubules and motors represent excellent targets for anti-cancer drugs but to make wise choices for developing therapeutics it is necessary to understand their contribution to cell division in detail. MCAK/Kif2C is a MT depolymerizing kinesin that controls MT length within the spindle and supresses chromosome instability (CIN). Using CRISPR/Cas9 engineered cells, rapamycin-dependent relocalization and long-term live imaging we have pinpointed the precise contribution that this protein makes to enhance the fidelity of chromosome segregation which will enable us to understand why this protein rescues CIN in tumorigenic cells and its future potential as a therapeutic target. MCAK/Kif2C is also strongly associated with centrosomes where it has the potential to suppress MT outgrowth and influence centrosome separation. We have identified two other poorly studied centrosome-associated kinesins, Kif25 and Kif9, that function in centrosome cohesion and centrosome satellite positioning respectively and that also impact centrosome separation and positioning. Altered centrosome positioning in cell culture has limited effects on cell viability. However, Both Kif9 and Kif25 are widely expressed in vertebrates. Because Kif25, in particular, is most highly expressed in brain it affords an opportunity to investigate the role of centrosome cohesion in vertebrate development and neural stem cell division using morpholinos directed against Kif25 introduced into early zebrafish embryos. We aim to use live and fixed-cell imaging tools and transgenic cell lines to investigate, with precision, the contribution that these kinesins make to preserving the fidelity of the genome and to long-term cell fate. Ultimately this knowledge base can be leveraged to develop new therapies that target kinesin enzymology or MT dynamics.