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Biogenesis of Giardia intestinalis mitosomes
Voleman, Luboš ; Doležal, Pavel (advisor) ; Faso, Carmen (referee) ; Dawson, Scott C. (referee)
7 ABSTRACT Mitochondria of opisthokonts undergo permanent fusion and fission throughout the cell cycle. Keeping these two processes in balance is vital for various aspects of mitochondrial and cellular homeostasis. Both mitochondrial fusion and division mechanisms are controlled by highly conserved dynamin-related GTPases that are present in all kingdoms of life. The aspects of mitochondrial dynamics outside the opisthokonts is, however, almost completely unexplored phenomenon. In our work, we introduced a tool for live imaging of the reduced forms of mitochondria into model organisms Giardia intestinalis and Trichomonas vaginalis, anaerobic protist parasites from the Excavata supergroup of Eukaryotes. Using this technique, we investigated the dynamics of the mitosomes, the simplest forms of mitochondria, of G. intestinalis. The division of mitosomes is restricted to Giardia mitosis and is absolutely synchronized with the process. The synchrony of the nuclear and the mitosomal division persists also during the encystation of the parasite. Surprisingly, the sole dynamin-related protein of the parasite seems not to be involved in mitosomal division. However, throughout the cell cycle mitosomes associate with the...
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Biogenesis of Giardia intestinalis mitosomes
Voleman, Luboš ; Doležal, Pavel (advisor) ; Faso, Carmen (referee) ; Dawson, Scott C. (referee)
7 ABSTRACT Mitochondria of opisthokonts undergo permanent fusion and fission throughout the cell cycle. Keeping these two processes in balance is vital for various aspects of mitochondrial and cellular homeostasis. Both mitochondrial fusion and division mechanisms are controlled by highly conserved dynamin-related GTPases that are present in all kingdoms of life. The aspects of mitochondrial dynamics outside the opisthokonts is, however, almost completely unexplored phenomenon. In our work, we introduced a tool for live imaging of the reduced forms of mitochondria into model organisms Giardia intestinalis and Trichomonas vaginalis, anaerobic protist parasites from the Excavata supergroup of Eukaryotes. Using this technique, we investigated the dynamics of the mitosomes, the simplest forms of mitochondria, of G. intestinalis. The division of mitosomes is restricted to Giardia mitosis and is absolutely synchronized with the process. The synchrony of the nuclear and the mitosomal division persists also during the encystation of the parasite. Surprisingly, the sole dynamin-related protein of the parasite seems not to be involved in mitosomal division. However, throughout the cell cycle mitosomes associate with the...
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The role of mitochondrial dynamics in cell death
Novotná, Eliška ; Rohlena, Jakub (advisor) ; Alán, Lukáš (referee)
Mitochondria form a dynamic reticulum, which fragments in apoptosis. It is assumed that proteins of mitochondrial dynamics participate in the intrinsic pathway of apoptosis and remodel mitochondrial membranes to release cytochrome c to the cytosol. The most important role in this process is played by Opa1, a protein involved in mitochondrial fusion, and by Drp1, which induces mitochondrial fission. During apoptosis, Opa1 remodels cristae in the inner mitochondrial membrane, which is crucial for effective release of cytochrome c to the cytosol. The role of Drp1 is less clear and is a subject of intense debate. Upon initiation of apoptosis Drp1 is recruited to mitochondria where it facilitates apoptotic pore formation and triggers fission. However, it appears that recruitment of Drp1 is not absolutely required for successful execution of apoptosis. In addition, mitochondrial dynamics is influenced by Bcl-2 family proteins. Recruitment of proapoptotic Bcl-2 proteins to mitochondrial outer membrane leads to inhibition of mitochondrial fusion, which enhances fragmented morphology of mitochondria. Although mitochondrial fragmentation in apoptosis is known for decades, its precise purpose remains to be elucidated.
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