Oxidative Stress‐Induced Depolymerization of Microtubules and Alteration of Mitochondrial Mass in Human Cells

Abstract

Mitochondrial biogenesis is a biological process that has been intensively studied over the past few years. However, the detailed molecular mechanism underlying this increase in mitochondria remains unclear. To investigate the mechanism of such a mitochondrial proliferation, we examined alterations in mitochondria of human osteosarcoma 143B cells that had been treated with 100 to 500 microM hydrogen peroxide (H2O2) for 48 h. The results showed that mitochondrial mass of the cell was increased with the increase of the concentration of H2O2. On the other hand, by using real-time PCR techniques, we observed the changes of mitochondrial DNA (mtDNA) content in the cells exposed to oxidative stress. The copy number of mtDNA was increased by treatment with a low dose of H2O2 but was drastically decreased after treatment with H2O2 higher than 300 microM. Transmission electron microscopic images revealed that mitochondria were abnormally proliferated in cells exposed to oxidative stress. Moreover, we found that the percentage of 143B cells arrested at the G2/M phase increased upon treatment with H2O2. Immunostaining and microtubule fractionation assay revealed that microtubules were depolymerized in the cells that had been treated with H2O2. To understand the effect of microtubules depolymerization on the mitochondrial mass, we treated the cells with several kinds of microtubule-active drugs, which arrest cultured cells at the G2/M phase. The results showed that mitochondrial mass and mtDNA copy number all were increased after such treatments. Taking these findings together, we suggest that oxidative stress-induced microtubule derangement is one of the molecular events involved in the increase of mitochondrial mass upon treatment of human cells with H2O2.

Increased mitochondrial DNA induces acquired docetaxel resistance in head and neck cancer cells

“…The mechanisms responsible for the increased amount of mtDNA in DRHEp2 are unknown. Lee et al (2005) reported that the amount of mtDNA was increased by treatment with paclitaxel or a low dose of hydrogen peroxide in human osteosarcoma cells. They also showed that mitochondria abnormally proliferated in cells.…”

Association between Mitochondrial DNA Copy Number in Peripheral Blood and Incident CKD in the Atherosclerosis Risk in Communities Study

“…18 In functional studies, exposure to hydrogen peroxide, a reactive oxygen species, resulted in damage to the DNA replication enzyme (polymerase g) in the mitochondria and a reduction in mtDNA copy number. 19,20 Exposure to TNF-a, an inflammatory cytokine, also generated reactive oxygen species and reduced mtDNA copy number in myocytes. 21 Cross-sectional studies of patients with CKD have shown that lower mitochondrial function, indicated by metabolites from urine and gene expression from peripheral blood, correlated with more severe CKD.…”

Tracking cellular stress with labeled FMAU reflects changes in mitochondrial TK2

“…The availability of the TK1-specific substrate (FLT) TK2-specific substrate (Ara-T), and TK2 inhibitor [bromovynil deoxyuridine (BVDU)] [12][13][14], provided the needed tools to measure the role of TK2 in FMAU retention. Previous experiments with H 2 O 2 and certain antineoplastic treatments have shown to increase mitochondrial DNA and mass [15][16][17][18][19]. These changes were assumed to be due to oxidative stress.…”