Study Reveals How Cell Compartments Cooperate to Defend Against Oxidative Stress

An international team led by researchers at The Hospital for Sick Children has discovered a previously unknown mechanism by which compartments within cells, specifically mitochondria and peroxisomes, work together to protect against oxidative stress. This finding, published in Science, offers new insight into how cells manage internal stress and damage, which is relevant to age-associated conditions such as diabetes and neurodegenerative diseases.

Mitochondria are known for generating the energy cells need, but this process also produces reactive oxygen species (ROS), byproducts that can damage cellular components and contribute to oxidative stress. Traditionally, it was believed that each organelle handled its own ROS independently. However, the team led by Peter Kim has identified a new protective mechanism: ROS produced in mitochondria can be transferred to peroxisomes through a contact point between the two organelles. 

Peroxisomes act as specialized sinks for these ROS, sparing mitochondria from damage. This movement of ROS between organelles, facilitated by proteins PTPIP51 (on mitochondria) and ACBD5 (on peroxisomes), challenges the previous assumption that organelle defense is isolated. Both proteins have been linked to neurodegeneration, highlighting the clinical relevance of this discovery.

Laura DiGiovanni, lead author, states, “Conventional dogma has always been that ROS are independently processed by organelles, but this work challenges that assumption by showing a mechanism by which peroxisomes directly mitigate mitochondrial ROS. This discovery demonstrates that inter-organelle dynamics actively contribute to antioxidant defense, introducing a new perspective on how cells manage oxidative stress.” 

“We are moving away from the idea that organelles operate in isolation and toward a more integrated view of how they communicate and coordinate to protect the cell,” says co-author Michael Schrader. “This is a fantastic example of how our independent discovery of ACBD5 and PTPIP51 as the bridging proteins has evolved into a multidisciplinary, international partnership, and we believe it has scope to change global understanding of how organelle interplay and cooperation impact on human health and disease.”