Publicação
The role of mitochondrial effectors of cell death in Δisc1 mutants
| Resumo: | Mitochondria are fundamental elements of the eukaryotic cell that have a wide variety of functions, including generation of metabolic energy through oxidative phosphorylation and biosynthesis of many key metabolites. In addition to the role in energy metabolism, regulation of cell death and ageing have recently emerged as a second major function of these organelles in humans and yeast. In recent years, the role of sphingolipids in mitochondria function, redox homeostasis and lifespan has attracted high attention due to their function in the regulation of stress responses, cell growth, differentiation, cell cycle arrest, endocytosis, ageing and apoptosis. In particular, ceramide is a bioactive sphingolipid that modulates cellular processes such as apoptosis and ageing. Saccharomyces cerevisiae has been used to understand the pathways involved in sphingolipid metabolism and their role in mitochondria function due to its simplicity in comparison with mammalian systems. Isc1p, the yeast orthologue of mammalian neutral sphingomyelinase (nSMase2), plays a crucial role in oxidative stress and chronological lifespan. It regulates ceramide levels and modulates ceramide signalling pathways that control mitochondria morphology and functional properties, as well as mitochondria-mediated cell death pathways. The knockout of ISC1 leads to an increase in sensitivity to oxidative stress and a premature ageing phenotype, and its short lifespan is mediated by cell death by apoptosis. The main goal of this work was to uncover the role of mitochondrial effectors of cell death in Δisc1 mutants. Previous studies indicated that deletion of the internal mitochondrial ubiquinone oxidoreductase (NDI1) or of the yeast orthologue of endonuclease G (NUC1) reverts the premature ageing of Δisc1 mutants. In order to identify the protein targets and mediators of signalling pathways that are deregulated in Δisc1 cells, and to characterize how these changes are related to Δisc1 phenotypes, in this work the role of Nuc1p and Ndi1p in Δisc1 phenotypes was investigated. The overall results will contribute to the characterization of the role of neutral sphingomyelinases and sphingolipid signaling in the modulation of mitochondria function to improve our understanding of processes associated with sphingolipid-related disorders, including ageing. |
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| Autores principais: | Silva, Diana Filipa Oliveira da |
| Assunto: | Ciências Naturais::Ciências Biológicas |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Mitochondria are fundamental elements of the eukaryotic cell that have a wide variety of functions, including generation of metabolic energy through oxidative phosphorylation and biosynthesis of many key metabolites. In addition to the role in energy metabolism, regulation of cell death and ageing have recently emerged as a second major function of these organelles in humans and yeast. In recent years, the role of sphingolipids in mitochondria function, redox homeostasis and lifespan has attracted high attention due to their function in the regulation of stress responses, cell growth, differentiation, cell cycle arrest, endocytosis, ageing and apoptosis. In particular, ceramide is a bioactive sphingolipid that modulates cellular processes such as apoptosis and ageing. Saccharomyces cerevisiae has been used to understand the pathways involved in sphingolipid metabolism and their role in mitochondria function due to its simplicity in comparison with mammalian systems. Isc1p, the yeast orthologue of mammalian neutral sphingomyelinase (nSMase2), plays a crucial role in oxidative stress and chronological lifespan. It regulates ceramide levels and modulates ceramide signalling pathways that control mitochondria morphology and functional properties, as well as mitochondria-mediated cell death pathways. The knockout of ISC1 leads to an increase in sensitivity to oxidative stress and a premature ageing phenotype, and its short lifespan is mediated by cell death by apoptosis. The main goal of this work was to uncover the role of mitochondrial effectors of cell death in Δisc1 mutants. Previous studies indicated that deletion of the internal mitochondrial ubiquinone oxidoreductase (NDI1) or of the yeast orthologue of endonuclease G (NUC1) reverts the premature ageing of Δisc1 mutants. In order to identify the protein targets and mediators of signalling pathways that are deregulated in Δisc1 cells, and to characterize how these changes are related to Δisc1 phenotypes, in this work the role of Nuc1p and Ndi1p in Δisc1 phenotypes was investigated. The overall results will contribute to the characterization of the role of neutral sphingomyelinases and sphingolipid signaling in the modulation of mitochondria function to improve our understanding of processes associated with sphingolipid-related disorders, including ageing. |
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