title: Dual phases of respiration chain defect-augmented mROS-mediated mCa 2+ stress during oxidative insult in normal and ρ 0 RBA1 astrocytes.
abstract: Mitochondrial respiratory chain (RC) deficits, resulting in augmented mitochondrial ROS (mROS) generation, underlie pathogenesis of astrocytes. However, mtDNA-depleted cells (ρ (0)) lacking RC have been reported to be either sensitive or resistant to apoptosis. In this study, we sought to determine the effects of RC-enhanced mitochondrial stress following oxidative insult. Using noninvasive fluorescence probe-coupled laser scanning imaging microscopy, the ability to resist oxidative stress and levels of mROS formation and mitochondrial calcium (mCa(2+)) were compared between two different astrocyte cell lines, control and ρ (0) astrocytes, over time upon oxidative stress. Our results showed that the cytoplasmic membrane becomes permeated with YO-PRO-1 dye at 150 and 130 minutes in RBA-1 and ρ (0) astrocytes, respectively. In contrast to RBA-1, 30 minutes after 20 mM H2O2 exposure, ρ (0) astrocytes formed marked plasma membrane blebs, lost the ability to retain Mito-R, and showed condensation of nuclei. Importantly, H2O2-induced ROS and accompanied mCa(2+) elevation in control showed higher levels than ρ (0) at early time point but vice versa at late time point. Our findings underscore dual phase of RC-defective cells harboring less mitochondrial stress due to low RC activity during short-term oxidative stress but augmented mROS-mediated mCa(2+) stress during severe oxidative insult.
authors.affiliation: Department of Neurology, Keelung Medical Center, Chang Gung Memorial Hospital, Keelung, Taiwan.
authors.forename: Tsung-I
authors.initials: TI
authors.lastname: Peng
authors.forename: Muh-Shi
authors.initials: MS
authors.lastname: Lin
authors.forename: Mei-Jie
authors.initials: MJ
authors.lastname: Jou
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism; D001583:Benzoxazoles / Q000737:chemistry; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004272:DNA, Mitochondrial; D004579:Electron Transport / Q000187:drug effects; D005456:Fluorescent Dyes / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000633:toxicity; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D011806:Quinolinium Compounds / Q000737:chemistry; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D059008:Time-Lapse Imaging
chemical_list: D001583:Benzoxazoles; D004272:DNA, Mitochondrial; D005456:Fluorescent Dyes; D011806:Quinolinium Compounds; D017382:Reactive Oxygen Species; C089813:YO-PRO 1; D006861:Hydrogen Peroxide; D002118:Calcium