Chemoptogenetic damage to mitochondria causes rapid telomere dysfunction.

Abstract

Reactive oxygen species (ROS) play important roles in aging, inflammation, and cancer. Mitochondria are an important source of ROS; however, the spatiotemporal ROS events underlying oxidative cellular damage from dysfunctional mitochondria remain unresolved. To this end, we have developed and validated a chemoptogenetic approach that uses a mitochondrially targeted fluorogen-activating peptide (Mito-FAP) to deliver a photosensitizer MG-2I dye exclusively to this organelle. Light-mediated activation (660 nm) of the Mito-FAP-MG-2I complex led to a rapid loss of mitochondrial respiration, decreased electron transport chain complex activity, and mitochondrial fragmentation. Importantly, one round of singlet oxygen produced a persistent secondary wave of mitochondrial superoxide and hydrogen peroxide lasting for over 48 h after the initial insult. By following ROS intermediates, we were able to detect hydrogen peroxide in the nucleus through ratiometric analysis of the oxidation of nuclear cysteine residues. Despite mitochondrial DNA (mtDNA) damage and nuclear oxidative stress induced by dysfunctional mitochondria, there was a lack of gross nuclear DNA strand breaks and apoptosis. Targeted telomere analysis revealed fragile telomeres and telomere loss as well as 53BP1-positive telomere dysfunction-induced foci (TIFs), indicating that DNA double-strand breaks occurred exclusively in telomeres as a direct consequence of mitochondrial dysfunction. These telomere defects activated ataxia-telangiectasia mutated (ATM)-mediated DNA damage repair signaling. Furthermore, ATM inhibition exacerbated the Mito-FAP-induced mitochondrial dysfunction and sensitized cells to apoptotic cell death. This profound sensitivity of telomeres through hydrogen peroxide induced by dysregulated mitochondria reveals a crucial mechanism of telomere-mitochondria communication underlying the pathophysiological role of mitochondrial ROS in human diseases.

• Authors: Wei Qian, Namrata Kumar, Vera Roginskaya, Elise Fouquerel, Patricia L Opresko, Sruti Shiva, Simon C Watkins, Dmytro Kolodieznyi, Marcel P Bruchez, Bennett Van Houten
• Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A) Vol. 116 Issue 37 Pg. 18435-18444 (09 10 2019) ISSN: 1091-6490 [Electronic] United States
• PMID: 31451640 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2019 the Author(s). Published by PNAS.

Chemical References

• DNA, Mitochondrial
• Reactive Oxygen Species
• TP53BP1 protein, human
• Tumor Suppressor p53-Binding Protein 1
• Superoxides
• Hydrogen Peroxide
• Oxygen

Topics

• Apoptosis (drug effects)
• Cell Cycle
• Cell Proliferation (drug effects)
• DNA Breaks, Double-Stranded
• DNA Damage
• DNA Repair
• DNA, Mitochondrial (metabolism)
• HEK293 Cells
• Humans
• Hydrogen Peroxide (metabolism, toxicity)
• Membrane Potentials
• Mitochondria (chemistry, drug effects, metabolism)
• Mitochondrial Diseases (metabolism)
• Oxidative Stress
• Oxygen (metabolism)
• Reactive Oxygen Species (metabolism, toxicity)
• Signal Transduction
• Superoxides (metabolism, toxicity)
• Telomere (metabolism)
• Tumor Suppressor p53-Binding Protein 1 (metabolism)