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Full-Text Articles in Life Sciences
Taxol-Stabilized Microtubules Can Position The Cytokinetic Furrow In Mammalian Cells, Katie Shannon, Julie C. Canman, C. Ben Moree, Jennifer S. Tirnauer, Edward D. Salmon
Taxol-Stabilized Microtubules Can Position The Cytokinetic Furrow In Mammalian Cells, Katie Shannon, Julie C. Canman, C. Ben Moree, Jennifer S. Tirnauer, Edward D. Salmon
Biological Sciences Faculty Research & Creative Works
How microtubules act to position the plane of cell division during cytokinesis is a topic of much debate. Recently, we showed that a subpopulation of stable microtubules extends past chromosomes and interacts with the cell cortex at the site of furrowing, suggesting that these stabilized microtubules may stimulate contractility. To test the hypothesis that stable microtubules can position furrows, we used taxol to rapidly suppress microtubule dynamics during various stages of mitosis in PtK1 cells. Cells with stabilized prometaphase or metaphase microtubule arrays were able to initiate furrowing when induced into anaphase by inhibition of the spindle checkpoint. In these …
Mad2 And Bubr1 Function In A Single Checkpoint Pathway That Responds To A Loss Of Tension, Katie Shannon, Julie C. Canman, Edward D. Salmon
Mad2 And Bubr1 Function In A Single Checkpoint Pathway That Responds To A Loss Of Tension, Katie Shannon, Julie C. Canman, Edward D. Salmon
Biological Sciences Faculty Research & Creative Works
The spindle checkpoint monitors microtubule attachment and tension at kinetochores to ensure proper chromosome segregation. Previously, PtK1 cells in hypothermic conditions (23°C) were shown to have a pronounced mitotic delay, despite having normal numbers of kinetochore microtubules. At 23°C, we found that PtK1 cells remained in metaphase for an average of 101 min, compared with 21 min for cells at 37°C. The metaphase delay at 23°C was abrogated by injection of Mad2 inhibitors, showing that Mad2 and the spindle checkpoint were responsible for the prolonged metaphase. Live cell imaging showed that kinetochore Mad2 became undetectable soon after chromosome congression. Measurements …
Anaphase Onset Does Not Require The Microtubule-Dependent Depletion Of Kinetochore And Centromere-Binding Proteins, Julie C. Canman, Nitin Sharma, Aaron F. Straight, Katie Shannon, Guowei Fang, Edward D. Salmon
Anaphase Onset Does Not Require The Microtubule-Dependent Depletion Of Kinetochore And Centromere-Binding Proteins, Julie C. Canman, Nitin Sharma, Aaron F. Straight, Katie Shannon, Guowei Fang, Edward D. Salmon
Biological Sciences Faculty Research & Creative Works
Spindle checkpoint proteins, such as Mad2 and BubR1, and the motors dynein/dynactin and CENP-E usually leave kinetochores prior to anaphase onset by microtubule-dependent mechanisms. Likewise, 'chromosome passenger proteins' including INCENP are depleted from the centromeres after anaphase onset and then move to the midzone complex, an event that is essential for cytokinesis. Here we test whether the cell cycle changes that occur at anaphase onset require or contribute to the depletion of kinetochore and centromere proteins independent of microtubules. This required the development of a novel non-antibody method to induce precocious anaphase onset in vivo by using a bacterially expressed …