Overactive Aurora-A At Spindle Poles In Prometaphase Disrupts Mitotic Progression

Diplôme Thèse Overactive Aurora-A At Spindle Poles In Prometaphase Disrupts Mitotic Progression eng 2023-08-14 2023-08-14 author Silvestri Ennio 918800 director Meraldi Patrick 0000-0001-9742-8756 108140 Département de physiologie cellulaire et métabolisme (PHYME) 149 10.13097/archive-ouverte/unige:174510 urn:nbn:ch:unige-1745103 Sc. Vie 251 Aurora-A kinase is one of the key kinases involved in the regulation of mitotic entry and its progression. During cell division, Aurora-A activity is spatiotemporally controlled to achieve faithful chromosome segregation. Aurora-A localizes to spindle poles where it triggers microtubule nucleation and modulates spindle microtubule dynamics to assemble bipolar spindle and kinetochore-microtubule attachments. At anaphase onset, however, the Aurora-A kinase localizes to the spindle midzone where it regulates the microtubule network for central spindle assembly. In cancers, cells overexpressing Aurora-A kinase often show chromosome segregation errors during cell division leading to binucleated cells, genomic instability and aneuploid progeny. Even today, the precise role of Aurora-A kinase in regulating different mitotic events and how its dysfunction causes cancer progression is poorly understood hitherto. Using the power of light-induced dimerization (LiD) in human cells expressing exogenous Aurora-A, I induced exogenous Aurora-A recruitment to the spindle poles during different stages of mitosis. This approach enabled me to manipulate the spatiotemporal activity of Aurora-A activity within the mitotic spindle. Using LiD, I observed that 1) forced recruitment of exogenous Aurora-A to the spindle poles increased Aurora-A activity during prometaphase. 2) Asynchronous cells failed to divide when exogenous Aurora-A was over-recruited to the spindle poles at prometaphase onset. 3) Recruitment of exogenous Aurora-A at the spindle poles increased kinetochore-fibers stability and promoted excessive attachments to kinetochores. 4) Removal of exogenous Aurora-A from the mitotic spindle by forced recruitment to mitochondria decreased kinetochore-fibers stability. 5) Partial inhibition of the mitotic kinase PLK1 partially rescued the increased kinetochore-fiber stability and mitotic failure when Aurora-A was overactive at spindle poles. These observations indicated that exogenous Aurora-A recruitment at the spindle poles perturbed kinase coordination in the establishment of bipolar spindle assembly. This increased the kinetochore-fibers stability and established excessive erroneous kinetochore-microtubule interactions disrupting cell division progression during anaphase. In conclusion, I propose that under overexpression conditions, exogenous Aurora-A overactivity at the spindle poles, via PLK1 activity, enhances spindle microtubule over-stabilization and prevents the cell from completing the division by rapidly exiting mitosis with double DNA. Aurora-A AurkA Light Induced Dimerization Dewey 612 134 Département de physiologie cellulaire et métabolisme 21C false 579 Groupe Meraldi Patrick (physiologie cellulaire et métabolisme) 922 a9c43fe2-dc64-41f1-bb82-97235f1af8cc Thesis Public Silvestri_These.pdf 7468874 application/pdf CC BY 2c75c54bf676db65c85d011c49547aae65c1f36676902f7243491e74a04ed473 6e70d6af-4f88-419b-b966-a926fd6bdd1f Imprimatur Public IMPRIMATUR Ennio SILVESTRI signé pa.pdf 156782 application/pdf c5fe3934a53e1deb2b07aba45c9b0b9e0ed7e129b07f1809ac0ade621588af7d openAccess Faculté de médecine / Section de médecine fondamentale / Département de physiologie cellulaire et métabolisme

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Overactive Aurora-A At Spindle Poles In Prometaphase Disrupts Mitotic Progression				2023	310	434

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Silvestri, Ennio

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