However, if you had a snapshot of each step, you would be able to cook the dish properly! The ability to take these snapshots was what I wanted for my chromosome study.Įstablishing our vertebrate cellular system was not straightforward. If you can only see a picture of the ingredients and the final dish, it is not easy to guess how the dish was cooked. My favourite analogy to explain this situation is “cooking”. Furthermore, it was not easy to examine the mechanism of mitotic chromosome assembly when we could only obtain pure populations of cells at the starting point (G2) and the end point (prometaphase chromosome). We thought that this gradual decrease in levels of an essential protein could provide cells time to adapt by upregulating compensatory pathways, thereby leading to unclear phenotypes. Therefore, the period of time required to deplete the target proteins entirely depends on the speed of their natural turnover, which can often be more than one cell cycle. In the case of conditional knockouts or RNA interference, we can only halt the expression of the gene of interest and the existing target proteins remain until they are eventually turned over. I combined KIF4A or SMC2 (a condensin subunit) conditional knockout cells with siRNA to deplete various combinations of chromosome scaffold proteins and showed that KIF4A, condensin, and topoisomerase II α co-operatively shape mitotic chromosomes.ĭuring the studies above, I was increasingly frustrated by the experimental limitations imposed by the vertebrate cell systems we could use at that time. It is also a major protein of the mitotic chromosome scaffold: a fraction of insoluble chromosomal non-histone proteins that concentrate along the axis of sister chromatids. KIF4A, kinesin family member 4A, is a multifunctional microtubule-motor protein that plays an important role in cytokinesis. In addition, through collaboration with Marcos Malumbres in Madrid, our promoter-hijack strategy was successfully applied to a mouse model and used to show that overexpression of Aurora B kinase can induce tumourigenesis in adult mice. We showed that the single alpha helix domain within INCENP can directly bind to microtubules and regulate Aurora B kinase activity. We introduced various mutants into INCENP conditional knockout cells to dissect its function. Aurora B kinase is the active subunit of the CPC and a key mitotic kinase.
INCENP is a scaffold subunit regulating the localisation and activity of the Chromosome Passenger Complex (CPC). In these cells, the addition of tetracycline or doxycycline stops the transcription from the target gene rather than from an exogenous cDNA, as was previously used for these conditional knockouts. I developed a “promoter-hijack strategy” to establish conditional knockout cells for multiply-spliced essential genes including INCENP and KIF4A. CAD knockout cell lines in chicken DT40 cells were my first encounter with genetic engineering techniques and I was fascinated by the power of them years before the CRISPR/Cas9 technology era.Īfter obtaining my Ph.D., I switched my focus to mitotic chromosome assembly and segregation. We found that CAD could induce nuclear apoptosis in vitro and later in vivo. One of these downstream factors is Caspase-Activated DNase (CAD). Caspases, major apoptotic proteases, activate downstream factors during apoptosis. I enjoy running, triathlon, water sports, and skiing.ĭuring my postgraduate studies with Bill Earnshaw, I dissected the biochemical mechanism of nuclear apoptosis. I have lived in Edinburgh for more than 25 years, but I am still discovering new parts of the city. I then came to Edinburgh with my husband. After graduation, I worked within a food factory at Co-op Kobe for 7 years and was involved in the development of new confectionaries. I studied Food Technology and Science at Kyoto University in Japan.
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