Mitokondriyal toksin etidyum bromür'ün hücre çekirdeği üzerindeki etkisi

Mitochondria take part in many cellular events, such as ATP generation by oxidative phosphorylation, cellular signaling, and apoptosis. These organelles contain a genome (mtDNA), inherited from a bacterial progenitor, which plays a major role in mitochondrial function. Damage to mtDNA can cause disease and may play a causal role in aging. In this thesis, we have engaged in two studies related to the study of mtDNA using the budding yeast Saccharomyces cerevisiae. Our major focus was on the cellular effects of the mitochondrial toxin ethidium bromide (EtBr). EtBr rapidly causes the destruction of mtDNA in S. cerevisiae and also engenders mtDNA loss in other organisms. For nearly fifty years, it has been suggested that EtBr solely affects mtDNA, leaving the nuclear DNA unscathed. However, we have now demonstrated that the effects of EtBr are, in fact, not limited to that organelle. We found that mutants lacking the ability to repair double-stranded DNA breaks in the nucleus are acutely sensitive to EtBr, even when mtDNA products or mtDNA itself are already lacking. We demonstrated that this toxic effect of EtBr in the nucleus causes an increase in nuclear genomic instability as measured by a novel assay of gene conversion. Our findings will have a major impact on the interpretation and design of experiments using this commonly used reagent. In additional studies, we are seeking new proteins involved in mitochondrial division. Mitochondria constantly fuse and divide, and mutations perturbing mitochondrial dynamics affect the segregation and maintenance of mtDNA. We created a yeast strain that is inviable when mitochondria are able to divide. Subsequently, we are seeking genes that when overexpressed would potentially alter the stoichiometry or regulation of complexes involved in mitochondrial division, leading to a block in this process. I will discuss our progress so far in seeking novel mitochondrial division components.