Identification of mitochondrial electron transport chain mutations that effect ageing

Thesis (Master)--Izmir Institute of Technology, Molecular Biology and Genetics, Izmir, 2009Includes bibliographical references (leaves: 31-35)Text in English; Abstract: Turkish and Englishix, 36 leaves.Aging can be defined as the loss of cell functionality by accumulation of deleterious effects. Mitochondrial electron transport chain (ETC) is the main site for reactive oxygen species (ROS) production. According to free radical theory of aging, free radicals produced by normal aerobic respiration accumulate by time and can cause aging. Although previous studies have identified that inner mitochondrial membrane complexes I and III are the major sites of ROS production, role of ETC genes in ROS production is a matter of debate. The purpose of the present study was to determine the ETC mutations that affect aging using S.cerevisiae as a model organism. Deletion mutants of S.cerevisiae lacking 73 genes of ETC were analyzed aging and we found out that nine mutants caused reduction in replicative lifespan. In addition to aging profiles, ROS production levels, respiratory competence and oxidative stress tolerance level of these deletion strains were also investigated. In order to verify lifespan modulation by these genes, they were all overexpressed in wild-type cells and aging profile of these cells was analyzed. Most of the cells lived longer than wild type control cells containing sham vector. Our results suggest that some of the ETC genes play important roles in mitochondrial functions and aging. We hope that our results will contribute to the field of aging studies

Identification of mitochondrial electron transport chain mutations that effect ageing

Thesis (Master)--Izmir Institute of Technology, Molecular Biology and Genetics, Izmir, 2009Includes bibliographical references (leaves: 31-35)Text in English; Abstract: Turkish and Englishix, 36 leaves.Aging can be defined as the loss of cell functionality by accumulation of deleterious effects. Mitochondrial electron transport chain (ETC) is the main site for reactive oxygen species (ROS) production. According to free radical theory of aging, free radicals produced by normal aerobic respiration accumulate by time and can cause aging. Although previous studies have identified that inner mitochondrial membrane complexes I and III are the major sites of ROS production, role of ETC genes in ROS production is a matter of debate. The purpose of the present study was to determine the ETC mutations that affect aging using S.cerevisiae as a model organism. Deletion mutants of S.cerevisiae lacking 73 genes of ETC were analyzed aging and we found out that nine mutants caused reduction in replicative lifespan. In addition to aging profiles, ROS production levels, respiratory competence and oxidative stress tolerance level of these deletion strains were also investigated. In order to verify lifespan modulation by these genes, they were all overexpressed in wild-type cells and aging profile of these cells was analyzed. Most of the cells lived longer than wild type control cells containing sham vector. Our results suggest that some of the ETC genes play important roles in mitochondrial functions and aging. We hope that our results will contribute to the field of aging studies

Identification of respiratory chain gene mutations that shorten replicative life span in yeast

Aging is the progressive accumulation of alterations in cells that elevates the risk of death. The mitochondrial theory of aging postulates that free radicals produced by the mitochondrial respiratory system contribute to the aging process. However, the roles of individual electron transfer chain (ETC) components in cellular aging have not been elucidated. In this study, we analyzed the replicative life span of 73 yeast deletion mutants lacking the genes of the mitochondrial electron transfer chain system, and found that nine of these mutants (δ nde1, δ tcm62, δ rip1, δ cyt1, δ qrc8, δ pet117, δ cox11, δ atp11, δ fmc1) had significantly shorter life spans. These mutants had lower rates of respiration and were slightly sensitive to exogenous administration of hydrogen peroxide. However, only two of them, δ nde1 and δ fmc1, produced higher amounts of intrinsic superoxide radicals in the presence of glucose compared to that of wild type cells. Interestingly, there were no significant alterations in the mitochondrial membrane potentials of these mutants. We speculate that the shorter life spans of ETC mutants result from multiple mechanisms including the low respiration rate and low energy production rather than just a ROS-dependent path. © 2011 Elsevier Inc

The roles of thiol oxidoreductases in yeast replicative aging

Thiol-based redox reactions are involved in the regulation of a variety of biological functions, such as protection against oxidative stress, signal transduction and protein folding. Some proteins involved in redox regulation have been shown to modulate life span in organisms from yeast to mammals. To assess the role of thiol oxidoreductases in aging on a genome-wide scale, we analyzed the replicative life span of yeast cells lacking known and candidate thiol oxidoreductases. The data suggest the role of several pathways in controlling yeast replicative life span, including thioredoxin reduction, protein folding and degradation, peroxide reduction, PIP3 signaling, and ATP synthesis. © 2010 Elsevier Ireland Ltd.DPT-2003K120690; TÜBA-GEBİP and NIH AG02151