Estudo da execução e controlo da proliferação de células humanas

• Autor(a) principal: Stryzhak, Anna Oleksandrivna
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/18613
• topic: MOB4; Microtúbulos; Fuso mitótico; Golgi; Interfase; Domínio/Área Científica::Ciências Médicas::Outras Ciências Médicas

Regulation of cell proliferation is of crucial importance to all multicellular organisms. The faithful transmission of genetic material relies upon the connection between chromosomes and the mitotic spindle. Errors can result in aneuploidy with consequent cell death or cancer formation. This work was dedicated to studying a human MOB4, an uncharacterised member of the MOB-like proteins family. Preliminary results from our laboratory point for MOB4 localisation at the mitotic spindle, MOB4 was observed at centrosomes. In the absence of MOB4, CENP-A is lost from kinetochores. MOB4 downregulation causes severe mitotic defects, mitotic block, and cell death. However, the mechanism by which this protein acts is undetermined. To better understand MOB4 function, nocodazole assays were held to study if MOB4 localisation could be altered when microtubules are depolymerised. Results suggest that MOB4 still localises at centrosomes. Afterwards, cells were treated with MG132 for metaphase block and analysis of MOB4 localisation at kinetochores. MOB4 does not appear to be localised at kinetochores in my working conditions. In addition, in cells treated with MG132, I observed MOB4 accumulations in the nucleus periphery of interphase cells. These results suggest that MOB4 accumulates in Golgi Complex during G2. In order to understand if these aggregates result from the MOB4 levels increase, I compared MOB4 protein levels of interphase cells and cells blocked in mitosis. Western blot results indicate that MOB4 concentration is stable during the cell cycle. Furthermore, I wanted to know if these aggregates are dependent on microtubules. Cells were incubated with MG132 and nocodazole. MOB4 aggregates were observed in cells with and without microtubules. Additionally, some cells with depolymerised microtubules present separate accumulations of MOB4. With this work, I can conclude that, in mitosis, MOB4 localises at centrosomes with and without the microtubules. MOB4 accumulates in Golgi Complex during G2, and these aggregates are independent of microtubules. Levels of MOB4 protein are stable during the cell cycle.