Title: Spatiotemporal autophagic degradation of oxidatively damaged organelles after photodynamic stress is amplified by mitochondrial reactive oxygen species
Authors: Rubio Romero, Noemí
Coupienne, Isabelle
Di Valentin, Emmanuel
Heirman, Ingeborg
Grooten, Johan
Piette, Jacques
Agostinis, Patrizia # ×
Issue Date: Sep-2012
Publisher: Landes Bioscience
Series Title: Autophagy vol:8 issue:9 pages:1312-1324
Abstract: Although reactive oxygen species (ROS) have been reported to evoke different autophagic pathways, how ROS or their secondary products modulate the selective clearance of oxidatively damaged organelles is less explored. To investigate the signaling role of ROS and the impact of their compartmentalization in autophagy pathways, we used murine fibrosarcoma L929 cells overexpressing different antioxidant enzymes targeted to the cytosol or mitochondria and subjected them to photodynamic (PD) stress with the endoplasmic reticulum (ER)-associated photosensitizer hypericin. We show that following apical ROS-mediated damage to the ER, predominantly cells overexpressing mitochondria-associated glutathione peroxidase 4 (GPX4) and manganese superoxide dismutase (SOD2) displayed attenuated kinetics of autophagosome formation and overall cell death, as detected by computerized time-lapse microscopy. Consistent with a primary ER photodamage, kinetics and colocalization studies revealed that photogenerated ROS induced an initial reticulophagy, followed by morphological changes in the mitochondrial network that preceded clearance of mitochondria by mitophagy. Overexpression of cytosolic and mitochondria-associated GPX4 retained the tubular mitochondrial network in response to PD stress and concomitantly blocked the progression toward mitophagy. Preventing the formation of phospholipid hydroperoxides and H 2O 2 in the cytosol as well as in the mitochondria significantly reduced cardiolipin peroxidation and apoptosis. All together, these results show that in response to apical ER photodamage ROS propagate to mitochondria, which in turn amplify ROS production, thereby contributing to two antagonizing processes, mitophagy and apoptosis.
ISSN: 1554-8627
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Cell Death Research & Therapy
× corresponding author
# (joint) last author

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